SYSTEM AND METHOD FOR COMMUNICATING OPTICAL SIGNALS BETWEEN A DATA SERVICE PROVIDER AND SUBSCRIBERS

SYSTEME ET PROCEDE DE TRANSMISSION DE SIGNAUX OPTIQUES ENTRE UN FOURNISSEUR DE SERVICES DE DONNEES ET DES ABONNES

English Abstract

An optical fiber network can include an outdoor laser transceiver node that
can be positioned in close proximity to the subscribers of an optical fiber
network. The outdoor laser transceiver node does not require active cooling
and heating devices that control the temperature surrounding the laser
transceiver node. The laser transceiver node can adjust a subscriber's
bandwidth on a subscription basis or on an as-needed basis. The laser
transceiver node can also offer data bandwidth to the subscriber in
preassigned increments. Additionally, the laser transceiver node lends itself
to efficient upgrading that can be performed entirely on the network side. The
laser transceiver node can also provide high speed symmetrical data
transmission. Further, the laser transceiver node can utilize off-the-shelf
hardware to generate optical signals such as Fabry-Perot (F-P) laser
transmitters, distributed feed back lasers (DFB), or vertical cavity surface
emitting lasers (VCSELs).

French Abstract

Réseau de fibres optiques pouvant comporter un noeud en extérieur d'émetteur-récepteur laser qui peut être implanté dans le voisinage immédiat d'abonnés audit réseau. Le noeud en extérieur d'émetteur-récepteur laser n'a pas besoin de dispositif actif de refroidissement et de chauffage pour la régulation de la température ambiante autour dudit noeud. Le noeud d'émetteur-récepteur laser peut ajuster la largeur de bande de l'abonné selon l'abonnement ou au gré des besoins. Le noeud d'émetteur-récepteur laser peut également proposer à l'abonné une largeur de bande pour données par tranches prédéterminées. Par ailleurs, ce noeud se prête à une mise à jour efficace qui peut être exécutée dans sa totalité sur le côté réseau. De plus, le noeud d'émetteur-récepteur laser peut assurer une transmission de données symétrique à grande vitesse. Enfin, pour la production de signaux optiques, on peut utiliser du matériel du commerce tel que des émetteurs laser Fabry-Perot (F-P), des lasers à résonateurs distribués ou des lasers à cavité verticale et à émission par la surface.

Claims

52
CLAIMS
What is claimed is:
1. An optical network system comprising:
a data service hub;
at least one optical tap;
at least one subscriber optical interface connected to the optical
tap;
a laser transceiver node disposed between the data service hub
and the optical tap, for communicating optical signals between the data
service hub
and the optical tap, and for apportioning bandwidth between subscribers of the
optical
network system, and
one or more optical waveguides connected between respective
optical taps and the laser transceiver node, for carrying the upstream optical
signals
and the downstream optical signals, whereby the number of the waveguides is
minimized while optical bandwidth for subscribers is controllable by the laser
transceiver node in response to subscriber demand.
2. The optical network system of claim 1, wherein the laser
transceiver node further comprises an optical tap routing device for
apportioning the
bandwidth between subscribers of the optical network system.

53
3. The optical network system of claim 1, wherein the laser
transceiver node further comprises:
at least one multiplexes coupled to an optical tap routing
device;
at least one optical transmitter connected to the at least
one multiplexer, for transmitting downstream optical signals received from the
data
service hub to at least one subscriber optical interface of the optical
network system;
and
at least one optical receiver connected to each
multiplexer, for receiving and converting upstream optical signals from at
least one
subscriber optical interface of the optical network system.
4. The optical network system of claim 1, wherein the laser
transceiver node further comprises at least one diplexer connected to the at
least one
optical transmitter and optical receiver, each diplexer combining downstream
RF
modulated optical signals received from the data service hub with the
downstream
optical signals, each diplexer being connected to a respective optical
waveguide.
5. The optical network system of claim 1, wherein the laser
transceiver node accepts gigabit Ethernet optical signals from the data
service hub and
partitions the Ethernet optical signals into a predetermined number of groups.

54
6. The optical network system of claim 1, wherein the laser
transceiver node comprises passive cooling devices in order to operate in a
temperature range between -40 degrees Celsius to 60 degrees Celsius.
7. The optical network system of claim 1, wherein the laser
transceiver node is mountable on a strand in an overhead plant environment.
8. The optical network system of claim 1, wherein the laser
transceiver node is housed within a pedestal in an underground plant
environment.
9. The optical network system of claim 1, wherein a distance
between the laser transceiver node and the data service hub comprises a range
between zero and eighty kilometers.
10. The optical network system of claim 1, wherein the laser
transceiver node comprises at least one optical transmitter, each optical
transmitter
comprises one of a Fabry-Perot laser, a distributed feedback laser, and a
vertical
cavity surface emitting laser (VCSEL).
11. The optical network system of claim 1, wherein the laser
transceiver node further comprises an optical tap routing device that
allocates
additional or reduced optical bandwidth to at least one subscriber optical
interface
relative to other subscriber optical interfaces in the optical network system.

55
12. The optical network system of claim 1, wherein the laser
transceiver node comprises an optical tap routing device that manages upstream
and
downstream optical signal protocols.
13. The optical network system of claim 11, wherein one of the
protocols comprises a time division multiple access protocol.
14. The optical network system of claim 1, wherein data bit rates
for the upstream and downstream optical signals are substantially symmetrical.
15. The optical network system of claim 1, wherein each optical
waveguide handles data rates of at least 450 Mb/s.
16. The optical network system of claim 1, wherein each optical
tap comprises at least one optical splitter.
17. The optical network system of claim 1, wherein one of the
optical taps servicing a particular group of subscriber optical interfaces is
connected
to another optical tap.
18. The optical network system of claim 1, wherein each optical
tap propagates upstream and downstream optical signals in addition to
downstream
RF modulated optical signals.

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19. The optical network system of claim l, wherein each subscriber
optical interface comprises an analog optical receiver, a digital optical
receiver, and a
digital optical transmitter.
20. The optical network system of claim l, wherein the optical
waveguides are a first set of optical waveguides, the optical network system
further
comprising a second set of optical waveguides disposed between the data
service hub
and laser transceiver node, the second set comprising a first waveguide for
carrying
upstream optical signals to the data service hub, and a second optical
waveguide for
carrying downstream optical signals to the laser transceiver node.

57
21. An optical network system comprising:
a data service hub;
at least one optical tap;
at least one subscriber optical interface connected to the optical
tap;
a laser transceiver node disposed between the data service hub
and the at least one subscriber optical interface, for communicating optical
signals
between the data service hub and the optical tap, and for apportioning
bandwidth
between subscribers of the optical network system, the optical tap being
disposed
within the laser transceiver node, and
one or more optical waveguides connected between respective
optical taps and the laser transceiver node, for carrying the upstream optical
signals
and the downstream optical signals, whereby the number of the waveguides is
minimized while optical bandwidth for subscribers is controllable by the laser
transceiver node in response to subscriber demand.
22. The optical network system of claim 21, wherein each optical
tap comprises an optical splitter.
23. The optical network system of claim 21, wherein one of the
optical taps servicing a particular group of subscriber optical interfaces is
connected
to another optical tap.

58
24. A method for communicating optical signals from a data
service provider to at least one subscriber comprising the steps of:
receiving downstream optical signals in a laser transceiver node
from the service provider;
dividing the downstream signals between preassigned
multiplexers in the laser transceiver node;
apportioning bandwidth between subscribers in the laser
transceiver node;
multiplexing the downstream signals at the preassigned
multiplexers; and
propagating respective combined downstream optical signals to
at least one subscriber via at least one optical tap along at least one
optical waveguide.
25. The method of claim 24, further comprising the step of
assigning subscribers to respective individual multiplexers.
26. The method of claim 24, further comprising the steps of
receiving downstream RF modulated optical signals from the
service provider; and
combining downstream optical signals with the downstream RF
modulated optical signals.

59
27. The method of claim 24, wherein the step of receiving
downstream optical signals further comprises the substep of receiving at least
one
gigabit or faster Ethernet optical signals from the data service provider.
28. The method of claim 24, further comprising the step of
operating the laser transceiver node between -40 degrees Celsius and 60
degrees
Celsius with passive temperature cooling devices.
29. The method of claim 24, further comprising the step of
mounting the laser transceiver node to a strand in an overhead plant
environment.
30. The method of claim 24, further comprising the step of housing
the laser transceiver node within a pedestal in an underground plant
environment.
31. The method of claim 24, further comprising the step of
providing one of video, telephone, and internet services via the optical
signals.
32. The method of claim 24, further comprising the steps of:
splitting combined downstream optical signals with at least one
optical tap; and
propagating the split downstream optical signals to at least one
subscriber along at least one optical waveguide.

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33. The method of claim 24, further comprising the step of
connecting between one and sixteen subscribers to a respective optical tap.
34. The method of claim 24, further comprising the step of feeding
one optical tap with optical signals from another optical tap.
35. The method of claim 24, further comprising the step of
servicing between one and sixteen subscribers with the at least one optical
waveguide.
36. The method of claim 24, wherein the step of converting
downstream electrical signals further comprises modulating at least one of
Fabry-
Perot lasers, distributed feedback lasers, and vertical cavity surface
emitting lasers
(VCSELs) to generate downstream optical signals.
37. The method of claim 24, wherein the step of apportioning
bandwidth further comprises the step of allocating additional or reduced
optical
bandwidth for at least one particular subscriber optical interface relative to
other
subscriber optical interfaces in the optical network system.
38. The method of claim 24, wherein the step of dividing the
downstream electrical signals further comprises the substep of using a time
division
multiplex protocol to divide the downstream electrical signals between
preassigned
multiplexers.

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39. The method of claim 24, further comprising the step of
maintaining substantially symmetrical data bit rates between the upstream
optical
signals and the downstream optical signals.
40. The method of claim 22, further comprising the step of
propagating the optical signals at data rates of at least 450 Mb/s.
41. A method for communicating optical signals from at least one
subscriber to a data service provider comprising the steps of:
propagating upstream optical signals originating from at least
one subscriber to at least one optical tap;
receiving upstream optical signals at a laser transceiver node
from the at least one optical tap;
converting the upstream optical signals to electrical signals at
the laser transceiver node;
combining upstream electrical signals in the laser transceiver
node;
apportioning bandwidth for at least one subscriber in the laser
transceiver node;
converting the combined upstream electrical signals into optical
signals; and
propagating the combined upstream optical signals to the data
service provider along at least one optical waveguide.

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42. The method of claim 41, further comprising the step of
operating the laser transceiver node between -40 degrees Celsius and 60
degrees
Celsius with passive temperature cooling devices.
43. The method of claim 41, further comprising the step of
mounting the laser transceiver node to a strand in an overhead plant
environment.
44. The method of claim 41, further comprising the step of housing
the laser transceiver node within a pedestal in an underground plant
environment.
45. The method of claim 41, further comprising the step of
providing one of video, telephone, and internet services via the optical
signals.
46. The method of claim 41, further comprising the step of
combining respective upstream optical signals originating from a plurality of
subscribers with at least one optical tap.
47. The method of claim 41, further comprising the step of
connecting between one and sixteen subscribers to a respective optical tap.
48. The method of claim 41, further comprising the step of
positioning the laser transceiver node closer to the optical taps relative to
the data
service provider.

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49. The method of claim 41, further comprising the step of feeding
one optical tap with optical signals from another optical tap.
50. The method of claim 41, further comprising the step of
servicing between one and sixteen subscribers with single optical waveguides
connected to respective individual multiplexers.
51. The method of claim 41, further comprising the step of
maintaining substantially symmetrical data bit rates between the downstream
optical
signals and the upstream optical signals.
52. The method of claim 41, further comprising the step of
propagating the optical signals at data rates of at least 450 Mb/s.

Description

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SYSTEM AND METHOD FOR COMMUNICATING OPTICAL SIGNALS
BETWEEN A DATA SERVICE PROVIDER AND SUBSCRIBERS
PRIORITY CLAIM TO PROVISIONAL APPLICATIONS
The present application claims priority to provisional patent application
entitled, "Systems to Provide Video, Voice and Data Services via Fiber Optic
Cable,"
filed on October 4, 2000 arid assigned U.S. Application Serial No. 60/237,894;
provisional patent application entitled, "Systems to Provide Video, Voice and
Data
services via Fiber Optic Cable - Part 2," filed on October 26, 2000 and
assigned U.S.
Application Serial No. 60/244,052; provisional patent application entitled,
"Systems
to Provide Video, Voice and Data services via Fiber Optic Cable - Part 3,"
filed on
December 28, 2000 and assigned U.S. Application Serial No. 60/258,837;
provisional
patent application entitled, "Protocol to Provide Voice and Data Services via
Fiber
Optic Cable," filed on October 27, 2000 and assigned U.S. Application Serial
No.
60/243,978; and provisional patent application entitled, "Protocol to Provide
Voice
and Data Services via Fiber Optic Cable-Part 2," filed on May 7, 2001 and
assigned
U.S. Application Serial No. 60/289,112, the entire contents of which are
incorporated
by reference.
TECHNICAL FIELD
The present invention relates to video, voice, and data communications. More
particularly, the present invention relates to a system and method for
communicating
optical signals between a data service provider and one or more subscribers.

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2
BACKGROUND OF THE INVENTION
The increasing reliance on communication networks to transmit more complex
data, such as voice and video traffic, is causing a very high demand for
bandwidth.
To resolve this demand for bandwidth, communication networks are relying more
upon optical fibers to transmit this complex data. Conventional communication
architectures that employ coaxial cables are slowly being replaced with
communication networks that comprise only fiber optic cables. One advantage
that
optical fibers have over coaxial cables is that a much greater amount of
information
can be carried on an optical fiber.
The Fiber-to-the-home (FTTH) optical network architecture has been a dream
of many data service providers because of the aforementioned capacity of
optical
fibers that enable the delivery of any mix of high-speed services to
businesses and
consumers over highly reliable networks. Related to FTTH is fiber to the
business
(FTTB). FTTH and FTTB architectures are desirable because of improved signal
quality, lower maintenance, and longer life of the hardware involved with such
systems. However, in the past, the cost of FTTH and FTTB architectures have
been
considered prohibitive. But now, because of the high demand for bandwidth and
the
current research and development of improved optical networks, FTTH and FTTB
have become a reality.
One example of a FTTH architecture that has been introduced by the industry
is a passive optical network (PON). While the PON architecture does provide an
all
fiber network, it has many drawbacks that make such a system impractical to
implement. One drawback of the PON architecture is that too many optical
cables
must originate at the head end or data service hub due to limitations in the
number of

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times an optical signal can be divided before the signal becomes too weak to
use.
Another drawback can be attributed to the passive nature of a PON network. In
other
words, because there are no active signal sources disposed between the data
service
hub and the subscriber, the maximum distance that can be achieved between the
data
service hub and a subscriber usually falls within the range of 10 to 20
kilometers.
Another significant drawback of the PON architecture is the high cost of the
equipment needed at the data service hub. For example, many PON architectures
support the full service access network (FSAN) which uses the asynchronous
transfer
mode (ATM) protocol. To support this protocol, rather complex and expensive
equipment is needed.
In addition to the high data service hub costs, conventional PON architectures
do not lend themselves to efficient upgrades. That is, conventional or
traditional PON
architectures force physical reconfiguration of the network by adding fibex
and muter
ports in order to increase the data speed of the network.
The data speeds in the downstream and upstream directions is another
drawback of the PON architecture. Conventional PON architectures typically
support
up to 622 Megabit per second speeds in the downstream direction while only
supporting maximum speeds of 155 Megabit per second speeds in the upstream
direction. Such unbalanced communication speeds between the upstream and
downstream communication directions is undesirable and is often referred to as
asymmetrical bandwidth. This asymmetrical bandwidth places a low ceiling or
low
threshold for the amount of information that can be transferred from a
subscriber to a
data service hub. The assymetrical bandwidth is a result of the high cost of
optical
components required.

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To overcome the asymmetrical bandwidth problem and the limited distance
between the subscriber and the data service hub, a conventional hybrid fiber-
to-the-
home (FTTH)/hybrid fiber-coax (I~'C) architecture has been proposed by the
industry. HFC is currently the architecture of choice for many cable
television
systems. In this FTTH/HFC architecture, an active signal source is placed
between
the data service hub and the subscriber. Typically, in this architecture, the
active
signal source comprises a router. This conventional muter has multiple data
ports that
are designed to support individual subscribers. More specifically, the
conventional
router uses a single port for each respective subscriber. Connected to each
data port
of the router is an optical fiber which, in turn, is connected to the
subscriber. The
connectivity between data ports and optical fibers with this conventional
FTTH/HFC
architecture yields a very fiber intensive last mile. It is noted that the
terms, "last
mile" and "first mile", are both generic terms used to describe the last
portion of an
optical network that connects to subscribers.
In addition to a high number of optical cables originating from the muter, the
FTTH/I~'C architecture requires radio frequency signals to be propagated along
traditional coaxial cables. Because of the use of coaxial cables, numerous
radio
frequency (RF) amplifiers are needed between the subscriber and the data
service hub.
For example, RF amplifiers are typically needed every one to three kilometers
in a
coaxial type system. The use of coaxial cables in the FTTH/HFC architecture
adds to
the overall cost of the system because two separate and distinct networks are
present
in such an architecture. In other words, the FTTH/HFC architecture has high
maintenance costs because of the completely different waveguides (coaxial
cable in
combination with optical fiber) in addition to the electrical and optical
equipment

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needed to support such two distinct systems. Stated more simply, the FTTH/HFC
architecture merely combines an optical network with an electrical network
where
both networks run independently of one another.
Another drawback of the FTTHIHFC architecture is that the active signal
5 source between the data service hub and subscriber, usually referred to as
the router,
requires a protected environment that occupies a significant amount of space.
That is,
the conventional router of the FTTH/HFC architecture requires an environmental
cabinet that must maintain the muter and related equipment at an optimum
temperature. To maintain this optimum temperature, the environmental cabinet
will
typically include active temperature control devices for heating and cooling
the
cabinet.
Stated more simply, the conventional muter of the FTTH/HF'C architecture
can only operate at standard room temperatures. Therefore, active cooling and
heating units that consume power are needed to maintain such an operating
temperature in all types of geographic areas and in all types of weather.
Unlike the FTTH/l~'C architecture that employs two separate communication
networks, another conventional hybrid fiber coax (HFC) architecture employs an
active signal sotuce between the data service hub and the subscriber that does
not
require a temperature controlled environmental cabinet. However, this active
signal
source disposed between the subscriber and the data service hub merely
provides
optical to electrical conversion of information signals. That is, the active
signal
source disposed between a subscriber and a data service hub in the HFC
architecture
converts downstream optical signals into electrical signals and upstream
electrical
signals into optical signals. The conventional HFC architecture relies upon
coaxial

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cable to support all signals in the last mile or so of the HFC network.
Therefore,
similar to the FTTH/HFC architecture, the conventional HFC architecture also
requires numerous RF amplifiers on the coaxial cable side of the network.
Another drawback of the conventional HFC architecture exists at the data
S service hub where numerous communication devices are needed to support the
data
signals propagating along the optical fibers between the active signal source
and the
data service hub. For example, the conventional HFC architecture typically
supports
telephony service by using equipment known generically as a host digital
terminal
(HDT). The HDT can include RF interfaces on the cable side, and interfaces to
either
I O a telephone switch or to a cable carrying signals to a switch on another
side.
Further, the data service hub of a conventional HFC architecture can further
include a cable modem termination system (CMTS). This system provides low
level
formatting and transmission functions for the data transmitted between the
data
service hub and the subscriber. The CMTS system can operate by-directionally,
15 meaning that it can send signals both downstream to subscribers and receive
signals
sent upstream from subscribers.
In addition to a CMTS, the conventional HFC architecture at the data service
hub typically includes several modulators that can comprise miniature
television
transmitters. Each modulator can convert video signals received from
satellites to an
20 assigned cha~mel (frequency) for transmission to subscribers. In addition
to the
modulators, a signal processor and other devices are used to collect the
entire suite of
television signals to be sent to subscribers. Typically, in a conventional HFC
architecture, there can be 78 or more such modulators or processors with their

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supporting equipment to service the analog TV tier. Additionally, similar
equipment
to serve the digital video tier is often used.
Another drawback of the conventional HFC architecture flows from the use of
the CMTS. Similar to the passive optical network (POI discussed above, the
CMTS
cannot support symmetrical bandwidth. That is, a bandwidth of the conventional
HFC architecture is typically asymmetrical because of the use of the data over
cable
service interface specification (DOCSIS). The nature of the DOCSIS standard is
that
it limits the upstream bandwidth available to subscribers. This can be a
direct result
of the limited upstream bandwidth available in an HFC plant. Such a property
is
undesirable for subscribers who need to transmit more complex data for
bandwidth
intensive services such as home servers or the exchange of audio files over
the
Internet.
In another variation of the conventional HFC architecture, the CMTS can be
part of the active signal source disposed between the subscriber and the data
service
hub. While this variation of the conventional HFC architecture enables the
active
signal source to perform some processing, the output of the active signal
source in this
architecture is still radio frequency energy and is propagated along coaxial
cables.
Accordingly, there is a need in the art for a system and method for
communicating optical signals between a data service provider and a subscriber
that
eliminates the use of coaxial cables and the related hardwaxe and software
necessary
to support the data signals propagating along the coaxial cables. There is
also a need
in the art for a system and method for commuuucating optical signals between a
data
service provider and a subscriber that supports high speed symmetrical data
transmission. In other words, there is a need in the art for an all fiber
optical network

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and method that can propagate the same bit rate downstream and upstream
to/from a
network subscriber. Further, there is also a need in the art for an optical
network
system and method that can service a large number of subscribers while
reducing the
number of connections at the data service hub.
There is also a need in the art for an active signal source that can be
disposed
between a data service hub and a subscriber that can be designed to withstand
outdoor
environmental conditions and that can be designed to hang on a strand or fit
in a
pedestal similar to conventional cable TV equipment that is placed within a
last mile
of a communications network. A fiuther need exists in the art for a system and
method for receiving at least one gigabit or faster Ethenlet communications in
optical
form from a data service hub and partition or apportion this optical bandwidth
into
distribution groups of a predetermined number. There is a further need in the
art for a
system and method that can allocate additional or reduced bandwidth based upon
the
demand of one or more subscribers on an optical network. Another need exists
in the
art for an optical network system that lends itself to efficient upgrading
that can be
performed entirely on the network side. In other words, there is a need in the
art for
an optical network system that allows upgrades to hardware to take place in
locations
between and within a data service hub and an active signal source disposed
between
the data service hub and a subscriber.
SUMMARY OF THE INVENTION
The present invention is generally drawn to a system and method for efficient
propagation of data and broadcast signals over an optical fiber network. More
specifically, the present invention is generally drawn to an optical network

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architecture that can include an outdoor Laser transceiver, or processing
node, that can
be positioned in close proximity to the subscribers of an optical fiber
network. For
example, the outdoor laser transceiver node can be designed to withstand
outdoor
environmental conditions and can be designed to hang on a strand or fit in a
pedestal
similar to conventional cable TV equipment that is placed within "the last
mile" of a
network.
Unlike the conventional routers disposed between the subscriber optical
interface and data service hub, the outdoor laser transceiver node does not
require
active cooling and heating devices that control the temperature surrounding
the laser
transceiver node. Further, the laser transceiver node can operate over a wide
temperature range. Because the Laser transceiver node does not require active
temperature controlling devices, the Laser transceiver node Lends itself to a
compact
electronic packaging volume that is typically smaller than the environmental
enclosures of conventional routers.
In contrast to conventional electronic cable TV equipment or conventional
optical processing nodes, the laser transceiver node can receive at Least one
gigabit or
faster Ethernet communications in optical form fr0111 the data service hub and
partition or apportion this optical bandwidth into distribution groups of a
predetermined number. In.one exemplary embodiment, the laser transceiver node
can
partition the optical bandwidth into distribution groups comprising at least
six groups
of at least sixteen subscribers.
Using an appropriate protocol, the laser transceiver node can allocate
additional or reduced bandwidth based upon the demand of one or more
subscribers.
That is, the laser transceiver node can adjust a subscriber's bandwidth on a

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subscription basis or on an as-needed basis. The laser transceiver node can
offer data
bandwidth to the subscriber in preassigned increments. For example, the laser
transceiver node can offer a particular subscriber or groups of subscribers
bandwidth
in units of 1, 2, 5, 10, 20, 50, 100, 200, and 450 Megabits per second (Mbls).
5 In addition to offering bandwidth in preassigned increments, the laser
transceiver node lends itself to efficient upgrading that can be performed
entirely on
the network side. In other words, upgrades to the hardware forming the laser
transceiver node can take place in locations between and within a data service
hub
(such as a headend) and the laser transceiver node themselves. This means that
the
10 subscriber side of the network can be left entirely intact during an
upgrade to the laser
transceiver node or data service hub or both.
The laser transceiver node can also provide high speed symmetrical data
transmission. In other words, the laser transceiver node can propagate the
same bit
rates downstream and upstream from a network subscriber. Further, the laser
transceiver node can also serve a larger number of subscribers while reducing
the
nuiuber of connections at the data service hub.
The flexibility and diversity of the laser transceiver node can be attributed
to
at least a few components. The laser transceiver node can comprise an optical
tap
routing device that is coupled to one or more tap multiplexers. The optical
tap routing
device can manage the interface with the data service hub optical signals and
can
route or divide or apportion the data service hub signals according to
individual tap
multiplexers that modulate laser transmitters to generate optical signals for
specific
optical taps. That is, unlike conventional routers which assign single ports
to
respective individual subscribers, the optical tap routing device can assign
multiple

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subscribers to a single port. More specifically, each tap multiplexes
connected to a
port of the optical tap routing device can service groups of subscribers. The
individual tap multiplexers can modulate laser transmitters to supply
downstream
optical signals to preassigned groups of subscribers coupled to optical taps.
From the
optical taps, subscribers can receive the downstream optical signals with
subscriber
optical interfaces.
The optical tap routing device can determine which tap multiplexes is to
receive a downstream electrical signal, or identify which of the plurality of
optical
taps originated an upstream signal. The optical tap routing device can also
format
data and implement the protocol required to send and receive data from each
individual subscriber connected to a respective optical tap (as will be
discussed
below). The optical tap routing device can comprise a computer or a hardwired
apparatus that executes a program defining a protocol for communications with
groups of subscribers assigned to single ports. The single ports are connected
to
respective tap multiplexers (discussed in further detail below).
The laser transceiver node further comprises off the-shelf hardware to
generate optical signals. For example, the laser transceiver node can comprise
one or
more Fabry-Perot (F-P) laser transmitters, distributed feed back lasers
(DFBs), or
vertical cavity surface emitting lasers (VCSELs). The laser transceiver node
can also
support unidirectional optical signals originating from the data service hub.
The laser
transceiver node can combine the unidirectional optical signals with
downstream
optical signals so that a single optical waveguide can connect the laser
transceiver
node to a respective subscriber. The unidirectional optical signals can
comprise
broadcast video or other similar RF modulated optical signals.

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12
The laser transceiver node is but one part of the present invention. The
present invention also comprises an efficient coupler, referred to as an
optical tap,
between the laser transceiver node and a respective subscriber optical
interface. The
optical tap can divide optical signals between a plurality of subscribers and
can be
simple in its design. For example, each optical tap can comprise an optical
sputter
that may feed one or more subscribers. Optical taps can be cascaded or they
can be
comiected in a star architecture from the laser transceiver node. The optical
tap can
also route signals to other optical taps that are downstream relative to a
respective
optical tap. The optical tap can also connect to a small number of optical
waveguides
so that high concentrations of optical waveguides are not present at any
particular
laser transceiver node. In other words, the optical tap can connect to a
predetermined
number of optical waveguides at a point remote from the Iaser transceiver node
so that
high concentrations of optical waveguides at the laser transceiver node can be
avoided.
As noted above, the optical tap and laser transceiver node are parts of the
present invention. The present invention can include a system that comprises
the
optical tap, the laser transceiver node, a data service hub, a subscriber
optical
interface, and optical waveguides connected between the optical taps and laser
transceiver node.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a functional block diagram of some core components of an exemplary
optical network architecture according to the present invention.

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13
Fig. 2 is a functional block diagram illustrating an exemplary optical network
architecture for the present invention.
Fig. 3 is a functional block diagram illustrating an exemplary data service
hub
of the present invention.
Fig. 4 is a functional block diagram illustrating an exemplary outdoor laser
transceiver node according to the present invention.
Fig. 5 is a functional block diagram illustrating an optical tap connected to
a
subscriber interface by a single optical waveguide according to one exemplary
embodiment of the present invention.
Fig. 6 is a functional block diagram illustrating an exemplary data service
hub
according to an alternative exemplary embodiment of the present invention
where
upstream optical signals and dov~mstream optical signals are propagated along
separate optical waveguides.
Fig. 7 is a functional block diagram illustrating an exemplary outdoor laser
transceiver node that can accept upstream and downstream optical signals that
are
propagated along separate optical waveguides in addition to unidirectional
signals that
can be mixed with the downstream optical signals.
Fig. 8 is a functional block diagram illustrating yet another exemplary
outdoor
laser transceiver node that can accept optical signals propagating in separate
upstream
and downstream optical waveguides in addition to multiple optical waveguides
that
propagate unidirectional signals.
Fig. 9 is a functional block diagram illustrating another exemplary
embodiment of a data service hub in which unidirectional signals such as video
or RF
signals are combined with downstream optical signals.

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14
Fig. 10 is a functional block diagram illustrating another exemplary outdoor
laser transceiver node that can process a combined downstream signal that
comprises
downstream optical signals in addition to unidirectional signals like RF
transmissions
or video data.
Fig. 11 is a functional block diagram illustrating another exemplary outdoor
laser transceiver node that employs dual transceivers between tap n
~.ultiplexers and
respective groups of subscribers.
Fig. 12 is a functional block diagram illustrating another exemplary outdoor
laser transceiver node that includes optical taps disposed within the laser
transceiver
node itself.
Fig. 13 is a logic flow diagram illustrating an exemplary method for
processing unidirectional and bidirectional optical signals with a laser
transceiver
node of the present invention.
Fig. 14 is a logic flow diagram illustrating an exemplary process for handling
downstream optical signals with a laser transceiver node according to the
present
invention.
Fig. 15 is a logic flow diagram illustrating an exemplary process for handling
upstream optical signals with an exemplary laser transceiver node according to
the
present invention.
Fig. 16 is a logic flow diagram illustrating the processing of unidirectional
and
bidirectional optical signals with an optical tap according to the present
invention.
Fig. 17 is a logic flow diagram illustrating the processing of unidirectional
optical signals and bidirectional optical signals with a subscriber interface
according
to the present invention.

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DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
The present invention may be embodied in hardware or software or a
combination thereof disposed within an optical network. The present invention
can
5 comprise a laser transceiver node disposed between a data service hub and a
subscriber that can allocate additional or reduced bandwidth based upon the
demand
of one or more subscribers. The present invention can support one gigabit or
faster
Ethernet communications in optical form to and from the data service hub and
partition or apportion this optical bandwidth into distribution groups of a
10 predetermined number. The present invention allows bandwidth to be offered
to
subscribers in preassigned increments. The flexibility and diversity of the
present
invention can be attributed to a few components.
The laser transceiver node of the present invention can comprise an optical
tap
routing device that is coupled to one or more tap multiplexers. The optical
tap routing
15 device can assign multiple subscribers to a single port that receives
downstream
optical signals from a data service hub. The laser transceiver node of the
present
invention can comprise off the-shelf hardware to generate optical signals. For
example, the laser transceiver node of the present invention can comprise one
or more
Fabry-Perot (F-P) lasers, distributed feedback lasers, or Vertical Cavity
Surface
Emitting Lasers (VCSELs) in the transmitters. The present invention can also
comprise efficient couplers, such as optical taps, between the laser
transceiver node
and a respective subscriber optical interface.
The optical tap can divide optical signals among a plurality of subscribers
and
can be simple in its design. The optical tap can connect to a limited number
of optical

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I6
waveguides at a point remote from the laser transceiver node so that high
concentrations of optical waveguides at the laser transceiver node can be
avoided. In
another exemplary embodiment, the optical tap can be disposed within the laser
transceiver node of the present invention.
Referring now to the drawings, in which like numerals represent like elements
throughout the several Figures, aspects of the present invention and the
illustrative
operating environment will be described.
Figure 1 is a functional block diagram illustrating an exemplary optical
network architecture 100 according to the present invention. The exemplary
optical
network architecture 100 comprises a data service hub 110 that is connected to
outdoor laser transceiver nodes 120. The laser transceiver nodes 120, in turn,
are
connected to an optical taps 130. The optical taps 130 can be connected to a
plurality
of subscriber optical interfaces 140. Between respective components of the
exemplary optical network architecture 100 are optical waveguides such as
optical
waveguides 150, 160, 170, and 180. The optical waveguides 150-180 are
illustrated
by arrows where the arrowheads of the arrows illustrate exemplary directions
of data
flow between respective components of the illustrative and exemplary optical
network
architecture 100. While only an individual laser transceiver node 120, an
individual
optical tap 130, and an individual subscriber optical interface 140 are
illustrated in
Figure 1, as will become apparent from Figure 2 and its corresponding
description, a
plurality of laser transceiver nodes 120, optical taps 130, and subscriber
optical
interfaces 140 can be employed without departing from the scope and spirit of
the
present invention. Typically, in many of the exemplary embodiments of the
present

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17
invention, multiple subscriber optical interfaces I40 are connected to one or
more
optical taps 130.
The outdoor laser transceiver node 120 can allocate additional or reduced
bandwidth based upon the demand of one or more subscribers that use the
subscriber
optical interfaces 140. The outdoor laser transceiver node 120 can be designed
to
withstand outdoor environmental conditions and can be designed to hang on a
strand
or fit in a pedestal or "hard hole." The outdoor laser transceiver node can
operate in a
temperature range between minus 40 degrees Celsius to plus 60 degrees Celsius.
The
laser transceiver node 120 can operate in this temperature range by using
passive
cooling devices that do not consume power.
Unlike the conventional routers disposed between the subscriber optical
interface 140 and data service hub 110, the outdoor laser transceiver node 120
does
not require active cooling and heating devices that control the temperature
surrounding the laser transceiver node 120. The present invention attempts to
place
more of the decision-making electronics at the data service hub 110 instead of
the
laser transceiver node 120. Typically, the decision-making electronics are
larger in
size and produce more heat than the electronics placed in the laser
transceiver node of
the present invention. Because the laser transceiver node 120 does not require
active
temperature controlling devices, the laser transceiver node 120 lends itself
to a
compact electronic packaging volume that is typically smaller than the
environmental
enclosures of conventional routers. Further details of the components that
make up
the laser transceiver node 120 will be discussed in further detail below with
respect to
Figures 4, 7, 8, 10, 11, and 12.

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18
In one exemplary embodiment of the present invention, three trunk optical
waveguides 160, 170, and 180 (that can comprise optical fibers) can conduct
optical
signals from the data service hub 1I0 to the outdoor Laser transceiver node
I20. It is
noted that the term "optical waveguide" used in the present application can
apply to
optical fibers, planar light guide circuits, and fiber optic pigtails and
other like optical
waveguides.
A first optical waveguide 160 can carry broadcast video and other signals.
The signals can be carried in a traditional cable television format wherein
the
broadcast signals are modulated onto carriers, which in turn, modulate an
optical
transmitter (not shown) in the data service hub 110. A second optical
waveguide 170
can carry downstream targeted services such as data and telephone services to
be
delivered to one or more subscriber optical interfaces 140. In addition to
carrying
subscriber-specific optical signals, the second optical waveguide 170 can also
propagate Internet protocol broadcast packets, as is understood by those
skilled in the
art.
In one exemplary embodiment, a third optical waveguide 180 can transport
data signals upstream from the outdoor laser transceiver node 120 to the data
service
hub 110. The optical signals propagated along the third optical waveguide 180
can
also comprise data and telephone services received from one or more
subscribers.
Similar to the second optical waveguide 170, the third optical waveguide 180
can also
carry IP broadcast packets, as is understood by those skilled in the art.
The third or upstream optical waveguide 180 is illustrated with dashed lines
to
indicate that it is merely an option or part of one exemplary embodiment
according to
the present invention. In other words, the third optical waveguide 180 can be

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19
removed. In another exemplary embodiment, the second optical waveguide 170
propagates optical signals in both the upstream and dovnmstream directions as
is
illustrated by the double arrows depicting the second optical waveguide 170.
In such
an exemplary embodiment where the second optical waveguide 170 propagates
bidirectiorial optical signals, only two optical waveguides 160, 170 would be
needed
to support the optical signals propagating between the data server's hub 110
in the
outdoor laser transceiver node 120. In another exemplary embodiment (not
shown), a
single optical waveguide can be the only link between the data service hub 110
and
the laser transceiver node 120. W such a single optical waveguide embodiment,
three
different wavelengths can be used for the upstream and downstream signals.
Alternatively, bi-directional data could be modulated on one wavelength.
In one exemplary embodiment, the optical tap 130 can comprise an 8-way
optical splitter. This means that the optical tap 130 comprising an 8-way
optical
splitter can divide downstream optical signals eight ways to serve eight
different
subscriber optical interfaces 140. In the upstream direction, the optical tap
130 can
combine the optical signals received from the eight subscriber optical
interfaces 140.
In another exemplary embodiment, the optical tap 130 can comprise a 4-way
splitter to service four subscriber optical interfaces 140. Yet in another
exemplary
embodiment, the optical tap 130 can further comprise a 4-way sputter that is
also a
pass-through tap meaning that a portion of the optical signal received at the
optical tap
130 can be extracted to serve the 4-way sputter contained therein while the
remaining
optical energy is propagated further downstream to another optical tap or
another
subscriber optical interface 140. The present invention is not limited to 4-
way and 8-

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way optical splitters. Other optical taps having fewer or more than 4-way or 8-
way
splits are not beyond the scope of the present invention.
Referring now to Figure 2, this Figure is a functional block diagram
illustrating an exemplary optical network architecture 100 that further
includes
5 subscriber groupings 200 that correspond with a respective outdoor laser
transceiver
node 120. Figure 2 illustrates the diversity of the exemplary optical network
architecture 100 where a number of optical waveguides 150 connected between
the
outdoor laser transceiver node 120 and the optical taps 130 is minmized.
Figure 2
also illustrates the diversity of subscriber groupings 200 that can be
achieved with the
IO optical tap 130.
Each optical tap 130 can comprise an optical splitter. The optical tap 130
allows multiple subscriber optical interfaces 140 to be coupled to a single
optical
waveguide 150 that is connected to the outdoor laser transceiver node 120. In
one
exemplary embodiment, six optical fibers 150 are designed to be connected to
the
15 outdoor laser transceiver node 120. Through the use of the optical taps
130, sixteen
subscribers can be assigned to each of the six optical fibers 150 that are
connected to
the outdoor laser transceiver node 120.
In another exemplary embodiment, twelve optical fibers 150 can be connected
to the outdoor laser transceiver node 120 while eight subscriber optical
interfaces 140
20 are assigned to each of the twelve optical fibers 150. Those skilled in the
art will
appreciate that the number of subscriber optical interfaces I40 assigned to a
particular
waveguide 150 that is connected between the outdoor laser transceiver node 120
and a
subscriber optical interface 140 (by way of the optical tap 130) can be varied
or
changed without departing from the scope and spirit of the present invention.
Further,

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21
those skilled in the art recognize that the actual number of subscriber
optical
interfaces 140 assigned to the particular fiber optic cable is dependent upon
the
amount of power available on a particular optical fiber 150.
As depicted in subscriber grouping 200, many configurations for supplying
communication services to subscribers are possible. For example, while optical
tap
130A can connect subscriber optical interfaces 140A1 through subscriber
optical
interface 140 to the outdoor Laser transmitter node 120, optical tap 130A can
also
connect other optical taps 130 such as optical tap 130 to the laser
transceiver node
120. The combinations of optical taps 130 with other optical taps 130 in
addition to
combinations of optical taps 130 with subscriber optical interfaces 140 are
limitless.
With the optical taps 130, concentrations of distribution optical waveguides
150 at the
laser transceiver node 120 can be reduced. Additionally, the total amount of
fiber
needed to service a subscriber grouping 200 can also be reduced.
With the active Laser transceiver node 120 of the present invention, the
I S distance between the laser transceiver node 120 and the data service hub l
I0 can
comprise a range between 0 and 80 kilometers. However, the present invention
is not
limited to this range. Those skilled in the art will appreciate that this
range can be
expanded by selecting various off the-shelf components that make up several of
the
devices of the present system.
Those skilled in the art will appreciate that other configurations of the
optical
waveguides disposed between the data service hub 110 and outdoor laser
transceiver
node 120 are not beyond the scope of the present invention. Because of the bi-
directional capability of optical waveguides, variations in the number and
directional
flow of the optical waveguides disposed between the data service hub 110 and
the

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22
outdoor laser transceiver node 120 can be made without departing from the
scope and
spirit of the present invention.
Refernng now to Figure 3, this functional block diagram illustrates an
exemplary data service hub 110 of the present invention. The exemplary data
service
hub 110 illustrated in Figure 3 is designed for a two tnmk optical waveguide
system.
That is, this data service hub 110 of Figure 3 is designed to send and receive
optical
signals to and from the outdoor laser transceiver node 120 along the first
optical
waveguide 160 and the second optical waveguide 170. With this exemplary
embodiment, the second optical waveguide 170 supports bi-directional data
flow. In
this way, the third optical waveguide 180 discussed above is not needed.
The data service hub 110 can comprise one or more modulators 310, 315 that
are designed to support television broadcast services. The one or more
modulators
310, 315 can be analog or digital type modulators. In one exemplary
embodiment,
there can be at least 78 modulators present in the data service hub 110. Those
skilled
in the art will appreciate that the number of modulators 310, 315 can be
varied
without departing from the scope and spirit of the present invention.
The signals from the modulators 310, 315 are combined in a combiner 320
where they are supplied to an optical transmitter 325 where the radio
frequency
signals generated by the modulators 310, 315 are converted into optical form.
The optical transmitter 325 can comprise one of Fabry-Perot (F-P) Laser
Transmitters, distributed feedback lasers (DFBs), or Vertical Cavity Surface
Emitting
Lasers (VCSELs). However, other types of optical transmitters are possible and
are
not beyond the scope of the present invention. With the aforementioned optical

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23
transmitters 325, the data service hub 110 lends itself to efficient upgrading
by using
off the-shelf hardware to generate optical signals.
The optical signals generated by the optical transmitter (often referred to as
the
unidirectional optical signals) are propagated to amplifier 330 such as an
Erbium
Doped Fiber Amplifier (EDFA) where the unidirectional optical signals are
amplified.
The amplified unidirectional optical signals are then propagated out of the
data
service hub 110 via a unidirectional signal output port 335 which is connected
to one
or more first optical waveguides 160.
The unidirectional signal output port 335 is connected to one or more first
optical waveguides 160 that support unidirectional optical signals originating
from the
data service hub 110 to a respective laser transceiver node 120. The data
service hub
110 illustrated in Figure 3 can further comprise an lizternet router 340. The
data
' service hub 110 can further comprise a telephone switch 345 that supports
telephony
service to the subscribers of the optical network system 100. However, other
telephony service such as Internet Protocol telephony can be supported by the
data
service hub 110. If only Internet Protocol telephony is supported by the data
service
hub 110, then it is apparent to those skilled in the art that the telephone
switch 345
could be eliminated in favor of lower cost VoIP equipment. For example, in
another
exemplary embodiment (not shown), the telephone switch 345 could be
substituted
with other telephone interface devices such as a soft switch and gateway. But
if the
telephone switch 345 is needed, it may be located remotely from the data
service hub
110 and can be connected through any of several conventional means of
interconnection.

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24
The data service hub 110 can ftirther comprise a logic interface 350 that is
connected to a laser transceiver node routing device 355. The logic interface
350 can
comprise a Voice over Internet Protocol (VoIP) gateway when required to
support
such a service. The laser transceiver node routing device 355 can comprise a
conventional roister that supports an interface protocol for communicating
with one or
more laser transceiver nodes 120. This interface protocol can comprise one of
gigabit
or faster Ethernet, Internet Protocol (IP) or SONET protocols. However, the
present
invention is not limited to these protocols. Other protocols can be used
without
departing from the scope and spirit of the present invention.
The logic interface 350 and laser transceiver node routing device 355 can read
packet headers originating from the laser transceiver nodes 120 and the
Internet roister
340. The logic interface 350 can also translate interfaces with the telephone
switch
345. After reading the packet headers, the logic interface 350 and laser
transceiver
node routing device 355 can determine where to send the packets of
information.
The Iaser transceiver node routing device 355 can supply downstream data
signals to respective optical transmitters 325. The data signals converted by
the
optical transmitters 325 can then be propagated to a bi-directional splitter
360. The
optical signals sent from the optical transmitter 325 into the bi-directional
splitter 360
can then be propagated towards a bi-directional data input/output port 365
that is
connected to a second optical waveguide 170 that supports bi-directional
optical data
signals between the data service hub 120 and a respective laser transceiver
node 120.
Upstream optical signals received from a respective laser transceiver node 120
can be
fed into the bi-directional data input/output port 365 where the optical
signals are then
forwarded to the bi-directional splitter 360. From the bi-directional splitter
360,

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respective optical receivers 370 can convert the upstream optical signals into
the
electrical domain. The upstream electrical signals generated by respective
optical
receivers 370 are then fed into the laser transceiver node routing device 355.
Each
optical receiver 370 can comprise one or more photoreceptors or photodiodes
that
5 convert optical signals into electrical signals.
When distances between the data service hub 110 and respective laser
transceiver nodes 120 are modest, the optical transmitters 325 can propagate
optical
signals at 1310 nm. But where distances between the data service hub 110 and
the
laser transceiver node are more extreme, the optical transmitters 325 can
propagate
10 the optical signals at wavelengths of 1550 nm with or without appropriate
amplification devices.
Those skilled in the art will appreciate that the selection of optical
transmitters
325 for each circuit may be optimized for the optical path lengths needed
between the
data service hub 110 and the outdoor laser transceiver node 120. Further,
those
15 skilled in the art will appreciate that the wavelengths discussed are
practical but are
only illustrative in nature. In some scenarios, it may be possible to use
communication windows at 1310 and 1550 nxn in different ways without departing
from the scope and spirit of the present invention. Further, the present
invention is
not limited to a 1310 and 1550 nm wavelength regions. Those skilled in the art
will
20 appreciate that smaller or larger wavelengths for the optical signals are
not beyond the
scope and spirit of the present invention.
Referring now to Figure 4, this Figure illustrates a functional block diagram
of
an exemplary outdoor laser transceiver node 120 of the present invention. In
this
exemplary embodiment, the laser transceiver node 120 can comprise a
unidirectional

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26
optical signal input port 40S that can receive optical signals propagated from
the data
service hub 110 that are propagated along a first optical waveguide 160. The
optical
signals received at the unidirectional optical signal input port 405 can
comprise
broadcast video data. The optical signals received at the input port 405 are
S propagated to an amplifier 410 such as an Erbium Doped Fiber Amplifier
(EDFA) in
which the optical signals are amplified. The amplified optical signals are
then
propagated to a splitter 415 that divides the broadcast video optical signals
among
diplexers 420 that are designed to forward optical signals to predetermined
subscriber
groups 200.
The laser transceiver node 120 can further comprise a bi-directional optical
signal input/output port 425 that connects the laser transceiver node 120 to a
second
optical waveguide 170 that supports bi-directional data flow between the data
service
hub 110 and laser transceiver node 120. Downstream optical signals flow
through the
bi-directional optical signal input/output port 425 to an optical waveguide
transceiver
1 S 430 that converts downstream optical signals into the electrical domain.
The optical
waveguide transceiver further converts upstream electrical signals into the
optical
domain. The optical waveguide transceiver 430 can comprise an
optical/electrical
converter and an electrical/optical converter.
Downstream and upstream electrical signals are communicated between the
optical waveguide transceiver 430 and an optical tap routing device 435. The
optical
tap routing device 435 can manage the interface with the data service hub
optical
signals and case route or divide or apportion the data service hub signals
according to
individual tap multiplexers 440 that communicate optical signals with one or
more
optical taps 130 and ultimately one or more subscriber optical interfaces 140.
It is

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27
noted that tap multiplexers 440 operate in the electrical domain to modulate
laser
transmitters in order to generate optical signals that are assigned to groups
of
subscribers coupled to one or more optical taps.
Optical tap routing device 435 is noticed of available upstream data packets
as
they arrive, by each tap multiplexes 440. The optical tap routing device is
connected
to each tap multiplexes 440 to receive these upstream data packets. The
optical tap
routing device 435 relays the packets to the data service hub 110 via the
optical
waveguide transceiver 430. The optical tap routing device 435 can build a
lookup
table from these upstream data packets coming to it from all tap multiplexers
440 (or
ports), by reading the source IP address of each packet, and associating it
with the tap
multiplexes 440 through which it came. This lookup table can then used to
route
packets in the downstream path. As each packet comes in from the optical
waveguide
transceiver 430, the optical tap routing device looks at the destination IP
address
(which is the same as the source IP address for the upstream packets). From
the
lookup table the optical tap routing device can determine which port is
connected to
that IP address, so it sends the packet to that port. This can be described as
a normal
layer 3 routes function as is understood by those skilled in the art.
The optical tap routing device 435 can assign multiple subscribers to a single
port. More specifically, the optical tap routing device 435 can service groups
of
subscribers with corresponding respective, single ports. The optical taps 130
coupled
to respective tap multiplexers 440 can supply downstream optical signals to
pre-
assigned groups of subscribers who receive the downstream optical signals with
the
subscriber optical interfaces 140.

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28
In other words, the optical tap routing device 435 can determine which tap
multiplexers 440 is to receive a downstream electrical signal, or identify
which of a
plurality of optical taps 130 propagated an upstream optical signal (that is
converted
to an electrical signal). The optical tap routing device 435 can format data
and
implement the protocol required to send and receive data from each individual
subscriber connected to a respective optical tap 130. The optical tap routing
device
435 can comprise a computer or a hardwired apparatus that executes a program
defining a protocol for commuzucations with groups of subscribers assigned to
individual ports. One exemplary embodiment of the program defining the
protocol is
discussed in copending and commonly assigned provisional patent application
entitled, "Protocol to Provide Voice and Data Services via Fiber Optic Cable,"
filed
on October 27, 2000 and assigned U.S. Application Serial No. 60/243,978, the
entire
contents of which are incorporated by reference. Another exemplary embodiment
of
the program defining the protocol is discussed in copending and commonly
assigned
provisional patent application entitled, "Protocol to Provide Voice aazd Data
Services
via Fiber Optic Cable-Part 2," filed on May 7, 2001 and assigned U.S.
Application
Serial No. 60/289,112, the entire contents of which are incorporated by
reference.
The single ports of the optical tap routing device are connected to respective
tap multiplexers 440. With the optical tap routing device 435, the laser
transceiver
node 120 can adjust a subscriber's bandwidth on a subscription basis or on an
as-
needed or demand basis. The laser transceiver node 120 via the optical tap
routing
device 435 can offer data bandwidth to subscribers in pre-assigned increments.
For
example, the laser transceiver node 120 via the optical tap routing device 435
can
offer a particular subscriber or groups of subscribers bandwidth in units of
1, 2, 5, 10,

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29
20, 50, 100, 200, and 450 Megabits per second (Mb/s). Those skilled in the art
will
appreciate that other subscriber bandwidth units are not beyond the scope of
the
present invention.
Electrical signals are communicated between the optical tap routing device
435 and respective tap multiplexers 440. The tap multiplexers 440 propagate
optical
signals to and from various groupings of subscribers. Each tap multiplexer 440
is
connected to a respective optical transmitter 325. As noted above, each
optical
transmitter 325 can comprise one of a Fabry-Perot (F-P) laser, a distributed
feedback
laser (DFB), or a Vertical Cavity Surface Emitting Laser (VCSEL). The optical
transmitters produce the downstream optical signals that are propagated
towards the
subscriber optical interfaces 140. Each tap multiplexer 440 is also coupled to
an
optical receiver 370. Each optical receiver 370, as noted above, can comprise
photoreceptors or photodiodes. Since the optical transmitters 325 and optical
receivers 370 can comprise off the-shelf hardware to generate and receive
respective
optical signals, the laser transceiver node 120 lends itself to efficient
upgrading and
maintenance to provide significantly increased data rates.
Each optical transmitter 325 and each optical receiver 370 are connected to a
respective bi-directional splitter 360. Each bi-directional splitter 360 in
turn is
connected to a diplexer 420 which combines the unidirectional optical signals
received from the splitter 415 with the downstream optical signals received
from
respective optical receivers 370. In this way, broadcast video services as
well as data
services can be supplied with a single optical waveguide such as a
distribution optical
waveguide 150 as illustrated in Figure 2. In other words, optical signals can
be

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coupled from each respective diplexer 420 to a combined signal inputloutput
port 445
that is connected to a respective distribution optical waveguide 150.
Unlike the conventional art, the laser transceiver node 120 does not employ a
conventional muter. The components of the laser transceiver node 120 can be
5 disposed within a compact electronic packaging volume. For example, the
laser
transceiver node 120 can be designed to hang on a strand or fit in a pedestal
similar to
conventional cable TV equipment that is placed within the "last," mile or
subscriber
proximate portions of a netvVOrk. It is noted that the term, "last mile," is a
generic
term often used to describe the last portion of an optical network that
connects to
10 subscribers.
Also because the optical tap routing device 435 is not a conventional router,
it
does not require active temperature controlling devices to maintain the
operating
environment at a specific temperature. In other words, the laser transceiver
node 120
can operate in a temperature range between minus 40 degrees Celsius to 60
degrees
I S Celsius in one exemplary embodiment.
While the laser transceiver node 120 does not comprise active temperature
controlling devices that consume power to maintain temperature of the laser
transceiver node 120 at a single temperature, the laser transceiver node 120
can
comprise one or more passive temperature controlling devices 450 that do not
20 consume power. The passive temperature controlling devices 450 can comprise
one
or more heat sinks or heat pipes that remove heat from the laser transceiver
node 120.
Those skilled in the art will appreciate that the present invention is not
limited to these
exemplary passive temperature controlling devices. Further, those skilled in
the art
will also appreciate the present invention is not limited to the exemplary
operating

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31
temperature range disclosed. With appropriate passive temperature controlling
devices 450, the operating temperature range of the laser transceiver node 120
can be
reduced or expanded.
W addition to the laser transceiver node's 120 ability to withstand harsh
outdoor environmental conditions, the Iaser transceiver node 120 can also
provide
high speed symmetrical data transmissions. In other words, the laser
transceiver node
120 can propagate the same bit rates downstream and upstream to and from a
network
subscriber. This is yet another advantage over conventional networks, which
typically caimot support symmetrical data transmissions as discussed in the
IO background section above. Further, the laser transceiver node 120 can also
serve a
large number of subscribers while reducing the number of connections at both
the
data service hub 110 and the laser transceiver node 120 itself.
The laser transceiver node 120 also lends itself to efficient upgrading that
can
be performed entirely on the network side or data service hub 110 side. That
is,
upgrades to the hardware forming the laser transceiver node 120 can take place
in
locations between and within the.data service hub 110 and the laser
transceiver node
120. This means that the subscriber side of the network (from distribution
optical
waveguides 150 to the subscriber optical interfaces 140) can be left entirely
in-tact
during an upgrade to the laser transceiver node 120 or data service hub 110 or
both.
The following is provided as an example of an upgrade that can be employed
utilizing the principles of the present invention. In one exemplary embodiment
of the
invention, the subscriber side of the laser transceiver node 120 can service
six groups
of 16 subscribers each for a total of up to 96 subscribers. Each group of 16
subscribers can share a data path of about 450 Mb/s speed. Six of these paths

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32
represents a total speed of 6 X 450 = 2.7 Gb/s. In the most basic form, the
data
communications path between the laser transceiver node 120 and the data
service hub
110 can operate at I Gb/s. Thus, while the data path to subscribers can
support up to
2.7 Gb/s, the data path to the network can only support 1 Gb/s. This means
that not
all of the subscriber bandwidth is useable. This is not normally a problem due
to the
statistical nature of bandwidth usage.
An upgrade could be to increase the 1 Gb/s data path speed between the Iaser
transceiver node 120 and the data service hub 110. This may be done by adding
more
1 Gb/s data paths. Adding one more path would increase the data rate to 2
Gb/s,
approaching the total subscriber-side data rate. A third data path would allow
the
network-side data rate to exceed the subscriber-side data rate. In other
exemplary
embodiments, the data rate on one link could rise from 1 Gb/s to 2 Gb/s then
to 10
Gb/s, so when this happens, a link can be upgraded without adding more optical
links.
The additional data paths (bandwidth) may be achieved by any of the methods
known to those skilled in the art. It may be accomplished by using a plurality
of
optical waveguide transceivers 430 operating over a plurality of optical
waveguides,
or they can operate over one optical waveguide at a plurality of wavelengths,
or it
may be that higher speed optical waveguide transceivers 430 could be used as
shown
above. Thus, by upgrading the laser transceiver node 120 and the data service
hub
110 to operate with more than a single 1 Gb/s link, a system upgrade is
effected
without having to make changes at the subscribers' premises.
Referring now to Figure 5, this Figure is a functional block diagram
illustrating an optical tap 130 connected to a subscriber optical interface
140 by a
single optical waveguide 150 according to one exemplary embodiment of the
present

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33
invention. The optical tap 130 can comprise a combined signal input/output
port that
is connected to another distribution optical waveguide that is connected to a
laser
transceiver node 120. As noted above, the optical tap 130 can comprise an
optical
splitter 510 that can be a 4-way or 8-way optical splitter. Other optical taps
having
fewer or more than 4-way or 8-way splits are not beyond the scope of the
present
invention. The optical tap can divide downstream optical signals to serve
respective
subscriber optical interfaces 140. In the exemplary embodiment in which the
optical
tap 130 comprises a 4-way optical tap, such an optical tap can be of the pass-
through
type, meaning that a portion of the downstream optical signals is extracted or
divided
to serve a 4-way splitter contained therein, while the rest of the optical
energy is
passed further downstream to other distribution optical waveguides 150.
The optical tap 130 is an efficient coupler that can communicate optical
signals between the laser transceiver node 120 and a respective subscriber
optical
interface 140. Optical taps 130 can be cascaded, or they can be connected in a
star
IS architecture from the laser transceiver node I20. As discussed above, the
optical tap
130 can also route signals to other optical taps that are downstream relative
to a
respective optical tap 130.
The optical tap 130 can also connect to a limited or small number of optical
waveguides so that high concentrations of optical waveguides are not present
at any
particular laser transceiver node 120. In other words, in one exemplary
embodiment,
the optical tap can connect to a limited number of optical waveguides 150 at a
point
remote from the laser transceiver node 120 so that lugh concentrations of
optical
waveguides 150 at a laser transceiver node can be avoided. However, those
skilled in
the art will appreciate that the optical tap I30 can be incorporated within
the laser

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34
transceiver node 120 as will be discussed in further detail below with respect
to
another exemplary embodiment of the laser transceiver node 120 as illustrated
in
Figure 12.
The subscriber optical interface 140 functions to convert downstream optical
signals received from the optical tap 130 into the electrical domain that can
be
processed with appropriate communication devices. The subscriber optical
interface
140 further functions to convert upstream electrical signals into upstream
optical
signals that can be propagated along a distribution optical waveguide I50 to
the
optical tap 130. The subscriber optical interface 140 can comprise an optical
diplexer
515 that divides the downstream optical signals received from the distribution
optical
waveguide 150 between a bi-directional optical signal sputter 520 and an
analog
optical receiver 525. The optical diplexer 515 can receive upstream optical
signals
generated by a digital optical transmitter 530. The digital optical
transmitter 530
converts electrical binary/digital signals to optical form so that the optical
signals can
be transmitted back to the data service hub 110. Conversely, the digital
optical
receiver 540 converts optical signals into electrical binary/digital signals
so that the
electrical signals can be handled by processor 550.
The present invention can propagate the optical signals at various
wavelengths. However, the wavelength regions discussed are practical and are
only
illustrative of exemplary embodiments. Those skilled in the art will
appreciate that
other wavelengths that are either higher or lower than or between the 1310 and
1550
mn wavelength regions are not beyond the scope of the present invention.
The analog optical receiver 525 can convert the downstream broadcast optical
video signals into modulated RF television signals that are propagated out of
the

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modulated RF unidirectional signal output 535. The modulated RF unidirectional
signal output 535 can feed to RF receivers such as television sets (not shown)
or
radios (not shown). The analog optical receiver 525 can process analog
modulated RF
transmission as well as digitally modulated RF transmissions for digital TV
5 applications.
The bi-directional optical signal splitter 520 can propagate combined optical
signals in their respective directions. That is, downstream optical signals
entering the
bi-directional optical sputter 520 from the optical the optical diplexer 515,
are
propagated to the digital optical receiver 540. Upstream optical signals
entering it
10 from the digital optical transmitter 530 are sent to optical diplexer 515
and then to
optical tap 130. The bi-directional optical signal splitter 520 is connected
to a digital
optical receiver 540 that converts downstream data optical signals into the
electrical
domain. Meanwhile the bi-directional optical signal splitter 520 is also
connected to a
digital optical transmitter 530 that converts upstream electrical signals into
the optical
15 domain.
The digital optical receiver 540 can comprise one or more photoreceptors or
photodiodes that convert optical signals into the electrical domain. The
digital optical
transmitter can comprise one or more lasers such as the Fabry-Perot (F-P)
Lasers,
distributed feedback lasers, and Vertical Cavity Surface Emitting Lasers
(VCSELs).
20 The digital optical receiver 540 and digital optical transmitter 530 are
connected to a processor 550 that selects data intended for the instant
subscriber
optical interface 140 based upon an embedded address. The data handled by the
processor 550 can comprise one or more of telephony and data services such as
an
Internet service. The processor 550 is connected to a telephone inputloutput
555 that

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36
can comprise an analog interface. The processor 550 is also comiected to a
data
interface 560 that can provide a link to computer devices, set top boxes, ISDN
phones, and other like devices. Alternatively, the data interface 560 can
comprise an
interface to a Voice over Internet Protocol (VoTP) telephone or Ethernet
telephone.
The data interface 560 can comprise one of Ethernet's (lOBaseT, 100BaseT,
Gigabit)
interface, HPNA interface, a universal serial bus (CJSB) an IEEE1394
interface, an
ADSL interface, and other like interfaces.
Referring now to Figure 6, this figure is a functional block diagram
illustrating
an exemplary data service hub 110B according to an alternative exemplary
embodiment of the present invention where upstream optical signals and
downstream
optical signals are propagated along separate optical waveguides such as the
second
optical waveguide 170 and the third optical waveguide 180 discussed above with
respect to Figure 1. In other words, in this exemplary embodiment, the second
optical
waveguide 170 is designed to carry only downstream optical signals while the
third
optical waveguide 180 is designed to carry only upstream optical signals from
the
laser transceiver node 120.
The exemplary data service hub 110B further comprises a downstream optical
signal output port 605 that is coupled to the second optical waveguide 170.
The data
service hub 110B further comprises an upstream optical signal input port that
is
coupled to the third optical waveguide 180. With the exemplary data service
hub
110B separate optical waveguides 180 and 170 carry the respective upstream and
downstream optical transmissions. With this exemplary embodiment, power can be
conserved since additional components that were previously used to combine and
separate the upstream and downstream optical signals are eliminated.

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37
This exemplary embodiment of the data service hub 110B can further reduce
distance limitations due to power loss and cross talk. In other words, at each
end of
an optical transmitter, which is supplying a lot of optical power compared
with the
received power, can create interference at the receiver due to incomplete
isolation
between the upstream and downstream optical signal directions. By utilizing
separate
optical waveguides for the upstream and downstream optical signals, this
interference
can be substantially reduced or eliminated.
Referring now to Figure 7, tlus Figure illustrates a functional block diagram
of
an exemplary outdoor laser transceiver node 120B that can accept upstream and
downstream optical signals that are propagated along separate optical
waveguides in
addition to unidirectional signals that can be mixed with downstream optical
signals.
In other words, the laser transceiver node 120B can be coupled to the
exemplary data
service hub 110B illustrated in Figure 6.
The laser transceiver node 120B can comprise a downstream optical signal
input port 705 that is coupled to the second optical waveguide I70 as
illustrated in
Figure 1. The downstream optical signal input port 705 is coupled to an
optical
receiver 710 that converts the downstream optical signals into the electrical
domain.
The optical receiver 710 in turn, feeds the electrical signals to the optical
tap routing
device 435.
The laser transceiver node 120B of Figure 7 can further comprise an optical
transmitter 720 that converts electrical signals received from the optical tap
routing
device 435 into the optical domain. The optical signals generated by the
optical
transmitter 720 are fed to an upstream optical signal output port 715. The
upstream
optical signal output port 715 is coupled to the third optical waveguide 180
as

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38
illustrated in Figure 1. Compared to the exemplary laser transceiver node 120A
illustrated in Figure 4, the bi-directional splitter 360 has been replaced
with a second
diplexer 4202. The optical transmitter 325 generates optical signals of a
wavelength
that is higher than the upstream optical signals produced by a respective
subscriber
optical interface 140. For example, in one exemplary embodiment, the optical
transmitter 325 can produce optical signals having wavelengths between 1410
and
1490 nm while the upstream optical signals remain at the 1310 nm wavelength
region.
As noted above, those skilled in the art will appreciate that the wavelengths
discussed are only illustrative in nature. In some scenarios, it may be
possible to use
communication Windows at 1310 and 1550 nm in different ways without departing
from the scope and spirit of the present invention. Further, the present
invention is
not limited to the wavelength regions discussed above. Those skilled in the
art will
appreciate that smaller or larger wavelengths for the optical signals are not
beyond the
scope and spirit of the present invention.
Because of the difference in wavelength regions between the upstream and
downstream optical signals, the additional diplexer 420 can be substituted for
the
previous bi-directional splitter 360 (illustrated in the exemplary embodiment
of Figure
4). The additional or substituted diplexer 420 does not exhibit the same loss
as the
previous bi-directional splitter 360 that is used in the exemplary embodiment
of
Figure 4. This substitution of the bi-directional sputter 360 with the
additional
diplexer 420 can also be applied to the subscriber optical interface 140. That
is, when
the upstream and downstream optical signals are operating at respective
different
wavelength regions, the bi-directional optical signal splitter 520 of the
subscriber
optical interface 140 can be substituted with a diplexer 420. The substitution
of the

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39
bi-directional splitter 360 with the diplexer 420 can reduce the optical loss
between
the laser transceiver node 120 and the subscriber optical interface 140.
Alternatively, if the laser transceiver node 120 is using the same wavelengths
for the upstream and downstream optical signals, the optical interface 140
uses the bi-
directional optical signal splitter 520 with a corresponding loss in optical
power as
illustrated in Figure 5. Those skilled in the art will appreciate that various
other
substitutions for the components of the laser transceiver node 120 can be made
without departing from the scope and spirit of the present invention.
Refernng now to Figure 8, this Figure illustrates another exemplary outdoor,
laser transceiver node 120C that can accept optical signals propagating from
separate
upstream and downstream optical waveguides in addition to multiple optical
waveguides that propagate unidirectional signals. In this exemplary
embodiment, the
laser transceiver node 120C of Figure 8 can comprise multiple unidirectional
signal
input ports 805 that are coupled to a plurality of first optical waveguides
160. In this
exemplary embodiment, compared to the laser transceiver node 120A of Figure 4
and
laser transceiver node 120B of Figure 7, the amplifier 410 has been removed
from the
laser transceiver node 120C as illustrated in Figure 8. The amplifier 410 is
taken out
of the laser transceiver node 120C and placed in the data service hub 110.
The optical signals propagating from the multiple first optical waveguides 160
are combined with the upstream and downstream optical signals originating from
the
second set of diplexers 4202 using the first set of diplexers 4201. This
design to
remove the amplifier 410 (that typically comprises an Erbium Doped Fiber
Amplifier
- EDFA) from the laser transceiver node 120C of Figure 8 to the data service
hub 110
and to include multiple first optical waveguides 160 feeding into the laser
transceiver

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node 120C, rnay be made on the basis of economics and optical waveguide
availability.
Figure 9 illustrates another exemplary embodiment of a data service hub 110D
in which unidirectional signals such as video or RF signals are combined with
5 downstream optical signals. In this exemplary embodiment, the data service
hub
110D further comprises a splitter 415 that feeds the broadcast video optical
signals to
respective diplexers 420. The respective diplexers 420 combine the broadcast
video
optical signals with the downstream data optical signals produced by
respective
optical transmitters 325. In this way, the first optical waveguide 160 as
illustrated in
10 Figure 1 can be eliminated since the broadcast video optical signals axe
combined
with the downstream data optical signals along the second optical waveguide
170.
Figure 10 illustrates another exemplary laser transceiver node 120D that can
be coupled to the data service hub 110D as illustrated in Figure 9. In this
exemplary
embodiment, the laser transceiver node 120D comprises a combined downstream
15 optical signal input 1005 that is coupled to a second optical waveguide 160
that
provides a combined downstream optical signal comprising broadcast video
services
and data service. The laser transceiver node 120D fwther comprises a diplexer
420
that feeds the broadcast video or RF signals to an amplifier 410. The
broadcast video
or RF optical signals are then sent to a splitter 415 which then sends the
optical
20 signals to the first set of diplexers 4201. The combination of the data
service hub
110D as illustrated in Figure-9 and the laser transceiver node 120D as
illustrated in
Figure 10 conserves optical waveguides between these two devices.
As noted above, in another exemplary embodiment, it may be possible to use
only a single fiber (not shown) to operatively link a data service hub 110 and
a laser

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41
transceiver node 120. In such an exemplary embodiment, different wavelengths
could
be used to propagate upstream and downstream optical signals.
Figure 11 is a functional block diagram illustrating another exemplary outdoor
laser transceiver node 120E that employs dual transceivers between tap
multiplexers
440 and respective groups of subscribers. In this embodiment the downstream
optical
signals originating from each respective tap multiplexer 440 are split
immediately
after the tap multiplexer 440. In this exemplary embodiment, each optical
transmitter
325 is designed to service only eight subscribers as opposed to sixteen
subscribers of
other embodiments. But each tap multiplexer 440 typically services sixteen or
fewer
subscribers.
In this way, the splitting loss attributed to the optical taps 130 can be
substantially reduced. For example, in other exemplary embodiments that do not
split
the downstream optical signals immediately after the tap multiplexer 440, such
embodiments are designed to service sixteen or fewer subscribers with a
corresponding theoretical splitting loss of approximately 14 dB (including an
allowance for losses). With the current exemplary embodiment that services
eight or
fewer subscribers, the theoretical splitting loss is reduced to approximately
10.5 dB.
In laser transceiver node 120E, the optical receivers 370 cannot be paralleled
because at all times one receiver 370 or the other is receiving signals from
respective
subscribers, while the other receiver 370 is not receiving signals. The
receiver 370
not receiving any upstream optical signals could output noise which would
interfere
with reception from the receiver 370 receiving upstream optical signals.
Therefore, a
switch 1105 can be employed to select the optical receiver 370 that is
currently
receiving an upstream optical signal. The tap multiplexer can control the
switch 1105

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42
since it knows which optical receiver 370 should be receiving upstream optical
signals
at any given moment of time.
Figure 12 is a functional block diagram illustrating another exemplary outdoor
laser transceiver node 120F that includes optical taps 130 disposed within the
laser
transceiver node 120F itself. In this architecture, optical waveguides 150
from each
subscriber optical interface 140 can be connected to the laser transceiver
node 120F.
Typically, the number of optical waveguides 150 that are connected to the
laser
transceiver node 120F is such that two laser transceiver nodes 150 are needed
to
support the number of optical waveguides 150. But when less than a maximum
number of subscribers exist, one laser transceiver node 120F can be used to
service
the existing service base. When the service base expands to a number requiring
an
additional laser transceiver node 120, the additional laser transceiver nodes
can be
added.
By placing the optical taps 130 within the laser transceiver node 120F, two or
more laser transceiver nodes 120F can be co-located with one another for the
reason
discussed above. In other words, this exemplary embodiment enables two or more
laser transceiver nodes 120F to be placed in close proximity to one another.
Such
placement of laser transceiver nodes 120F can conserve power and result in
significant cost savings. Furthermore, with such a co-location design, future
expansion of the optical architecture 100 can easily be obtained. That is, one
laser
transceiver nodes 120F can be installed until more subscribers join the
optical
network architecture 100 requiring the Iaser transceiver node. Optical
waveguides
150 can be connected to the co-located laser transceiver nodes as more
subscribers
join the optical network architecture 100.

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43
Referring now to Figure 13, this figure illustrates an exemplary method for
processing unidirectional and bi-directional optical signals with a laser
transceiver
node 120 of the present invention. Basically, Figure 13 provides an overview
of the
processing performed by the laser transceiver node 120.
Certain steps in the process described below must naturally precede others for
the present invention to function as described. However, the present invention
is not
limited to the order of the steps described if such order or sequence does not
alter the
functionality of the present invention. That is, it is recognized that some
steps may be
performed before or after other steps without departing from the scope and
spirit of
the present invention.
Step 1305 is the first step in the exemplary laser transceiver node overview
process 1300. In step 1305, downstream RF modulated optical signals are
amplified
by the amplifier 410 as illustrated in Figure 4. As noted above, the amplifier
410 can
comprise an Erbium Doped Fiber Amplifier (EDFA). However, other optical
amplifiers are not beyond the scope of the present invention.
Next, in Step 1307, bandwidth between respective subscribers can be
apportioned with the optical tap routing device 435. In other words, the
optical tap
routing device 435 can adjust a subscriber's bandwidth in accordance with a
subscription or on an as-needed basis. The optical tap routing device 435 can
offer a
particular subscriber or groups of subscribers bandwidth in units of 1, 2, 5,
10, 20, 50,
100, 200, and 450 Mb/s.
In Step 1310, the downstream RF modulated optical signals are combined with
the downstream optical signals originating from the tap multiplexers 440. The

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44
combining of the downstream optical signals can occur in diplexers 420.
Subsequently, in Step 1315, the combined downstream optical signals are
propagated
along the distribution optical waveguides 150 to respective assigned groups of
optical
taps 200.
In Step 1320, upstream optical signals are received by optical receivers 370
and then converted to upstream electrical signals. The upstream electrical
signals are
sent to respective tap multiplexers 440. Electrical signals received from
respective
tap multiplexers 440 are combined in the optical tap routing device 435
according to
Step 1325. Also in Step 1325, the upstream electrical signals from the optical
tap
routing device 435 can be converted into the optical domain with either am
optical
waveguide transceiver 430 or an optical transmitter 720. In Step 1330, the
upstream
optical signals are propagated towards the data service hub 110 via a bi-
directional
optical waveguide 170 or a dedicated upstream optical waveguide 180.
Referring now to Figure 14, this figure illustrates a logic flow diagram of an
exemplary process for handling downstream optical signals with a laser
transceiver
node 120 according to the present invention. More specifically, the logic flow
diagram of Figure 14 illustrates an exemplary method for communicating optical
signals from a data service provider I IO to at least one subscriber.
As noted above, certain steps in the process described below must naturally
proceed others for the present invention to function as described. However,
the
present invention is not limited to the order of steps described if such order
or
sequence does not alter the functionality of the present invention. That is,
it is

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4S
recognized that some steps may be performed before or after other steps
without
departing from the scope and spirit of the present invention.
Step 1405 is the first step in the exemplary process 1400 for communicating
optical signals from a data service provider to at least one subscriber. In
step 1405,
S downstream optical signals are received at the laser transceiver node 120.
For
example, downstream optical signals can be received at the unidirectional
optical
signal input port 405 as illustrated in Figure 4. Further, downstream optical
signals
can also be received at the bi-directional optical signal input/output port
425 also
illustrated in Figure 4.
Next in Step 1410, the downstream optical signals can be converted to the
electrical domain. In other words, the downstream optical signals received at
the bi-
directional output signal input/output port 425 can be converted into the
electrical
domain with an optical waveguide transceiver 430. As noted above, the optical
waveguide transceiver 430 can comprise an optical/electrical converter. Next,
in Step
I S 1415 the optical tap routing device 435 can divide the converted
electrical signals
between tap multiplexers 440 that are assigned to groups of optical taps 130.
In Step
1420, the downstream bandwidth can be apportioned for subscribers with the
optical
tap routing device 435.
In this step, the optical tap routing device 435 can apportion bandwidth to
groups of subscribers based upon a subscription or based upon a current
demand. The
optical tap routing device 435 can partition the bandwidth in units of 1, 2,
S, 10, 20,
S0, 100, 200, and 4S0 Mb/s. However, the present invention is not limited to
these
increments. Other increments of bandwidth are not beyond the scope and spirit
of the

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46
present invention. The optical tap routing device 435 can apportion bandwidth
in this
way by executing a program defining a protocol for communications with groups
of
subscribers assigned to single ports. The single ports are connected to the
respective
tap multiplexers 440.
In Step 1425, the downstream electrical signals processed by the optical tap
routing device 435 are multiplexed with the tap multiplexers 440.
Subsequently, in
Step 1430 the downstream electrical signals can be converted into downstream
optical
signals with the optical transmitters 325. As noted above, the optical
transmitters 325
can comprise one of Fabry-Perot (F-P) lasers, distributed feedback lasers, and
Vertical
Cavity Surface Emitting Lasers (VCSELs). However, as noted above, other types
of
lasers are not beyond the scope of the present invention.
liz Step 1435 the unidirectional RF modulated optical signals received from
the first optical waveguide 160 can be split into a plurality of paths with a
splitter 415.
Next, in Step 1440 the downstream paths of the RF modulated optical signals
are
combined with the paths of the downstream optical signals originating from the
tap
multiplexers 440.
Figure 15 illustrates a logic flow diagram of an exemplary process for
handling upstream optical signals with an exemplary laser transceiver node 120
according to the present invention. More specifically, Figure 15 illustrates a
process
for communicating optical signals from at least one subscriber to a data
service
provider hub.
As noted above, certain steps in the process described below must naturally
proceed others for the present invention to function as described. However,
the

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47
present invention is not limited to the order of the steps described if such
order or
sequence does not alter the functionality of the present invention. That is,
it is
recognized that some steps may be performed before or after other steps
without
departing from the scope and spirit of the present invention.
Step 1505 is the first step in the exemplary laser transceiver node upstream
process 1500. In Step 1505, upstream optical signals originating from
subscribers to
optical taps 130 are propagated along distribution optical waveguides 150.
Next, the
upstream optical signals are converted by a optical receiver 370 in Step 1510.
In Step
1515, the upstream electrical signals are combined at the optical tap routing
device
435. Next, in Step 1520 upstream bandwidth for subscribers is apportioned with
the
optical tap routing device 435 similar to how the downstream optical bandwidth
is
apportioned as discussed above with respect to Figure 14.
For the upstream optical signals, the optical tap routing device 435 can
employ
time division multiple access (TDMA) in order to service or support signals
originating from multiple tap multiplexers 440. As may be apparent to those
skilled
in the art, in time division multiple access the optical tap routing device
435 switches
in time from one tap multiplexer 440 to another tap multiplexer 440. In
contrast, for
the downstream optical signals, the optical tap routing device 435 employs
time
division multiplexing (TDM). As is apparent to those skilled in the art, time
division
multiplexing occurs when the optical tap routing device 435 sends data to
multiple tap
multiplexers 440. In time division multiplexing, the signal is never removed,
so
receiving clocks remain synchronized.

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In Step 1525, the combined upstream electrical signals are converted to
upstream optical signals with either the optical waveguide transceiver 430 or
the
optical transmitter 720. Next, in Step 1530, the combined upstream optical
signals are
propagated along an optical waveguide such as the second optical waveguide 170
or
third optical waveguide 180 to the data service hub 110.
Figure 16 is a logic flow diagram illustrating the processing of
unidirectional
and bi-directional optical signals with an optical tap 130 according to the
present
invention. As noted above, certain steps in the process described below must
naturally proceed others for the present invention to function as described.
However,
the present invention is not limited to the order of steps described if such
order or
sequence does not alter the functionality of the present invention. That is,
it is
recognized that some steps may be performed before or after other steps
without
departing from the scope and spirit of the present invention.
Step 1605 is the first step in the optical tap process 1600. Step 1605 diverts
signals from an optical waveguide such as a distribution optical waveguide 150
coupled to a laser transceiver node to the combined signal input/output port
505.
Next in Step 1610 downstream optical signals that were tapped are split with
the
optical splitter 510. The optical splitter 510 can split the downstream
optical signals
to one or more subscriber interfaces or other taps or sputters or combination
thereof
via distribution optical waveguides 150. In Step 1615, the downstream tap
combined
optical signals can be propagated to and upstream optical signal from
respective
subscribers can be received and combined with the optical sputter 510.

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Figure 17 is a logic flow diagram illustrating exemplary processing of
unidirectional optical signals and bi-directional optical signals with a
subscriber
optical interface 140 according to the present invention. As noted above,
certain steps
in the process described below must naturally proceed others for the present
invention
to function as described. However, the present invention is not limited to the
order of
steps described if such order or sequence does not alter the functionality of
the present
invention. That is, it is recognized that some steps may be performed before
or after
other steps without departing from the scope and spirit of the present
invention.
Step 1705 is the first step in the subscriber optical interface process 1700.
In
Step 1705, combined downstream optical signals are received with an optical
diplaxer
515. Next, in Step 1710, the RF modulated downstream optical signals are
separated
from the downstream data optical signals originating from the tap multiplexers
440.
In Step 1715, the downstream RF modulated optical signals are converted to
downstream electrical optical signals with an analog optical receiver 525. As
noted
above, the analog optical receiver 525 can handle both analog modulated
signals in
addition to digitally modulated signals for digital TV applications.
In Step 1720, the upstream electrical signals are converted to optical signals
with the digital optical transmitter 530. As noted above, the digital optical
transmitter
530 can comprise one of a Fabry-Perot (F-P) laser, a distributed feedback
(DFB)
laser, and a vertical cavity surface emitting laser (VCSEL) or other similar
lasers.
The upstream electrical signals can be generated from a telephone input/output
port
555 or a data interface 560 or both (as discussed above).

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In Step 1725, downstream electrical signals emitted from the digital optical
receiver 540 are received by a processor 550. The processor 550, in turn,
propagates
these electrical signals to appropriate output devices such as the telephone
input/output port 555 or data interface 560 or both. As noted above, the
telephone
5 input/output port 555 or the data interface 560 or both can generate
upstream
electrical signals that are sent to the processor 550 and then converted into
the optical
domain with the digital optical transmitter 530.
Those skilled in the art will appreciate that the optical network architecture
100 of the present invention can provide at least one of video, telephone, and
10 computer communication services via the optical signals. Also, those
skilled in the
art will appreciate that the video layer comprising the RF modulated signals
can be
removed from the exemplary optical network architecture 100 without departing
from
the scope and spirit of the present invention.
With the present invention, an all fiber optical network and method that can
IS propagate the same bit rate downstream and upstream to/from a network
subscriber
are provided. Further, the present invention provides an optical network
system and
method that can service a large number of subscribers while reducing the
number of
connections at the data service hub.
The present invention also provides an active signal source that can be
20 disposed between a data service hub and a subscriber and that can be
designed to
withstand outdoor environmental conditions. The present invention can also be
designed to hang on a strand or fit in a pedestal similar to conventional
cable TV
equipment that is placed within a last mile of a communications network. The
system
and method of the present invention can receive at least one Gigabit or faster
Ethernet

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communications in optical form from a data service hub and partition or
apportion
this optical bandwidth into distribution groups of a predetermined number. The
system and method of the present invention can allocate additional or reduced
bandwidth based upon the demand of one or more subscribers on an optical
network.
Additionally, the optical network system of the present invention lends itself
to
efficient upgrading that can be performed entirely on the network side. In
other
words, the optical network system allows upgrades to hardware to take place in
locations between and within a data service hub and an active signal source
disposed
between the data service hub and a subscriber.
It should be understood that the foregoing relates only to illustrate the
embodiments of the present invention, and that numerous changes may be made
therein without departing from the scope and spirit of the invention as
defined by the
following claims.

Representative Drawing