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Patent 2595365 Summary

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(12) Patent: (11) CA 2595365
(54) English Title: BASE TRANSCEIVER STATION (BTS) SYNCHRONIZATION
(54) French Title: SYNCHRONISATION DE STATION E/R DE BASE
Status: Deemed expired
Bibliographic Data
(51) International Patent Classification (IPC):
  • H04W 56/00 (2009.01)
  • H04W 64/00 (2009.01)
  • H04B 7/26 (2006.01)
(72) Inventors :
  • ANDERSON, ROBERT J. (United States of America)
  • SHEEHAN, JOSEPH W. (United States of America)
  • BULL, JEFFREY F. (United States of America)
  • COHEN, BENJAMIN HERMAN (United States of America)
(73) Owners :
  • TRUEPOSITION, INC. (United States of America)
(71) Applicants :
  • TRUEPOSITION, INC. (United States of America)
(74) Agent: CASSAN MACLEAN IP AGENCY INC.
(74) Associate agent:
(45) Issued: 2013-01-22
(86) PCT Filing Date: 2005-04-25
(87) Open to Public Inspection: 2006-08-24
Examination requested: 2009-11-06
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US2005/014188
(87) International Publication Number: WO2006/088472
(85) National Entry: 2007-07-19

(30) Application Priority Data:
Application No. Country/Territory Date
60/652,265 United States of America 2005-02-11

Abstracts

English Abstract




In a network overlay wireless location solution for a GSM or UMTS
communications network, spectrum utilization can be made far more efficient by
synchronizing the BTSs, which can require distributing a timing signal to all
BTSs, or installing a satellite-based timing unit in each site. The present
invention provides an architecture in which Location Measurement Units (LMUs)
are installed at some or all of the BTS sites for the purpose of locating
wireless devices. The LMUs are used to measure the timing of various uplink
and/or downlink signals in the cellular network in support of various location
techniques. These LMUs may include a GPS-based timing reference module, which
may be used to synchronize the time bases of all LMUs. To reduce the overall
cost of BTS synchronization, the LMU distributes timing signals, including a
periodic electrical pulse as well as time description information, on a serial
or other interface, which is available for other nodes to use for
synchronization. The format of the electrical pulse and time description
information is modified through hardware and software to adapt to the various
formats required by various BTS types. For example, the BTSs with co-located
LMUs can receive a synchronization signal with little or no hardware cost. The
External Interface Unit (EIU) described herein may be used to adapt to various
BTS hardware formats. For BTS sites not equipped with an LMU, a Timing
Measurement Unit (TMU) can be used. The TMU has the single function of
providing BTS time signals in the same formats as provided by the LMUs. The
time signals provided by the TMUs are synchronous to the signals provided by
the LMUs. This timing-only TMU has a lower cost than the LMU because it does
not support the uplink or downlink signal measurement functions. This approach
allows a cellular operator to synchronize BTSs at a relatively low cost.


French Abstract

La présente invention concerne, dans un dispositif de radiolocalisation par chevauchement de réseaux pour un réseau de communications GSM ou UMTS, la possibilité d'utiliser de façon bien plus efficace le spectre par une synchronisation des stations de base, ce qui peut nécessiter une répartition d'un signal de synchronisation à toutes les stations de base, ou l'installation d'un module de synchronisation satellitaire sur chaque site. L'invention propose donc une architecture dans laquelle des modules de mesure pour localisation ou "LMU" (Location Management Units) sont installées sur certains au moins des sites de stations de base de façon à localiser les dispositifs radio. Les LMU servent à mesurer par diverses techniques de localisation la temporisation de certains signaux remontants et/ou descendants dans le réseau cellulaire. Ces LMU peuvent comporter un module de référence de synchronisation à base de GPS, pouvant servir à synchroniser les bases de temps de tous les LMU. Pour réduire le coût d'ensemble de la synchronisation des stations de base, le LMU distribue des signaux de synchronisation, comprenant une impulsion électrique périodique ainsi qu'une information de description de synchronisation, par une interface série ou autre, disponible pour que d'autre noeuds puissent l'utiliser aux fins de synchronisation. Le format de l'impulsion électrique et de l'information de description de synchronisation est modifié par le logiciel et le matériel de façon à s'adapter au divers formats demandés par les différents types de stations de base. Ainsi, les stations de base à LMU en co-situation peuvent recevoir un signal de synchronisation sans grande exigence matérielle. L'interface externe ou "EIU" (External Interface Unit) de l'invention permet également de s'adapter aux divers formats matériels des stations de base. Pour les sites de stations de base non équipés de LMU, on peut utiliser un module de chronométrage ou "TMU" (Timing Measurement Unit). Ce module sert uniquement à fournir à la station de base des signaux de synchronisation dans les mêmes formats que ceux fournis par les LMU. Les signaux de chronométrie fournis par les TMU sont synchrone avec les signaux fournis par les LMU. Un tel TMU uniquement chronomètre coûte moins cher que le LMU parce qu'il est dégagé des fonctions de mesure du signal remontant ou descendant. Cette logique de fonctionnement permet à l'opérateur cellulaire de synchroniser les stations de base à un coût relativement faible.

Claims

Note: Claims are shown in the official language in which they were submitted.





WHAT IS CLAIMED IS:


1. In a network overlay wireless location for a wireless communications system

comprising a network of Base Transceiver Stations, BTSs (104), a method of
improving spectrum, comprising synchronizing a plurality of BTSs (104) with a
timing signals,
wherein at least one BTS (104) is provided with a respective timing signal
from a Location Measurement Unit, LMU (200A), said LMU having uplink or
downlink signal measurement functions for wireless location measurement, said
LMU
comprising a GPS-based timing reference module (202A) for generating a timing
reference signal and means for generating the respective timing signal
including the
timing reference signal;
wherein at least one BTS (104) is provided with a respective timing signal
from a Timing Measurement Unit, TMU, having the single function of providing
said
respective timing signal, said TMU comprising a GPS-based timing reference
module
for generating a timing reference signal and means for generating the
respective
timing signal including the timing reference signal, wherein the timing signal

provided by the TMU is synchronous to the timing signals provided by the LMU
and
the TMU lacks uplink or downlink signal measurement functions; and
wherein the respective timing signals for synchronizing said plurality of BTSs

(104) are provided by one of a LMU (200A) and TMU and wherein the respective
timing signals generated by the one of LMU and TMU are each synchronized
within a
pre-specified degree of accuracy with the timing signals generated by the
other of
LMU (200A) and TMU.


2. A method as recited in claim 1, wherein said wireless communications system

comprises a GSM communications network.


3. A method as recited in claim 1, wherein said wireless communications system

comprises a UMTS communications network.


4. A method as recited in claim 1, wherein the LMUs and TMUs generate timing
signals, including a periodic electrical pulse as well as time description
information.


28




5. A network overlay wireless location system for a wireless communications
system,
said wireless communications system comprising a network of Base Transceiver
Stations, BTSs, said wireless location system comprising:
synchronizing means for synchronizing a plurality of BTSs with timing
signals,
said synchronizing means including:
a Location Measurement Unit, LMU provided in at least one BTS, said at least
one BTS being provided with a respective timing signal from the LMU, said LMU
having uplink or downlink signal measurement functions for wireless location
measurement, said LMU comprising a GPS-based timing reference module for
generating a timing reference signal and means for generating the respective
timing
signal including the timing reference signal;
a Timing Measurement Unit, TMU, provided in at least one BTS, said BTS
being provided with a respective timing signal from the TMU, said TMU having
the
single function of providing said respective timing signal, said TMU
comprising a
GPS-based timing reference module for generating a timing reference signal and

means for generating the respective timing signal including the timing
reference
signal, wherein the timing signal provided by the TMU is synchronous to the
timing
signals provided by the LMU and the TMU lacks uplink or downlink signal
measurement functions; and
wherein the respective timing signals for synchronizing said plurality of BTSs

are provided by one of a LMU and TMU and wherein the respective timing signals

generated by the one of LMU and TMU are each synchronized within a pre-
specified
degree of accuracy with the timing signals generated by the other of LMU and
TMU.

6. A wireless location system as recited in claim 5, wherein said wireless
communications system comprises a GSM communications network.


7. A wireless location system as recited in claim 5, wherein said wireless
communications system comprises a UMTS communications network.


8. A wireless location system as recited in claim 5, wherein the LMUs and TMUs

generate timing signals, including a periodic electrical pulse as well as time

description information.



29

Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02595365 2012-08-01

BASE TRANSCEIVER STATION (BTS) SYNCHRONIZATION
CROSS REFERENCE
[0001] The present application claims priority to U.S. Provisional
Application No. 60/652,265, filed on February 11, 2005, entitled "Base
Transceiver
Station (BTS) Synchronization.".

FIELD OF THE INVENTION
[0002] The present invention relates generally to the field of wireless
location
and associated wireless communications systems, and more particularly, but not
exclusively, to a system for synchronizing Base Transceiver Stations (BTSs) of
a
GSM or UMTS network coupled with an overlay wireless location system (WLS).
BACKGROUND OF THE INVENTION
[0003] The present invention is especially suited, but not necessarily limited
to, use with GSM and UMTS systems and the like. GSM stands for Global System
for
Mobile communication and is a digital mobile telephone system widely used in
Europe and other parts of the world, whereas UMTS stands for Universal Mobile
Telecommunications System and is a third-generation (3G) broadband system
based
on the GSM standard. This specification describes systems and methods to
provide
Global Positioning System (GPS)-derived timing information to base stations of
a
wireless communications system, for the purposes of network synchronization.
For
example, GSM network synchronization can benefit a wireless carrier in several
ways, hi unsynchronized GSM networks, the co-channel interference created by
frequency reuse can be reduced by synchronization. A reduced noise/co-channel
interference level allows for tighter frequency reuse patterns, thus allowing
the carrier
to increase system capacity (e.g., Erlang capacity) or improve voice/data
quality.
SUMMARY OF THE INVENTION
[0004] The following statements summarize several important aspects of the
present invention, which are described in greater detail herein:
1. In a network overlay wireless location solution for a wireless
communications system comprising a network of Base Transceiver Stations
(BTSs),
1


CA 02595365 2012-11-07

for example GSM or UMTS communications network, a method and system of
improving spectrum by synchronizing the BTSs.
2. A method and system as recited above, wherein a timing signal is provided
to
each BTS by either a Location Measurement Unit (LMU) or a Timing Measurement
Unit
(TMU).
3. A method and system as recited above, wherein each LMU and TMU
comprises a GPS-based timing reference module and means for generating a
periodic
timing signal which is synchronized within a pre-specified degree of accuracy
with the
timing signals generated by each other LMU and TMU.
4. A method and system as recited above, wherein the LMUs are used to
measure the timing of various uplink and/or downlink signals in the cellular
network in
support of various location techniques.
5. A method and system as recited above, wherein the LMUs and TMUs
distribute timing signals, including a periodic electrical pulse as well as
time description
information.
6. A method and system as recited above, wherein the format of the electrical
pulse and time description information are modified through hardware and
software to
adapt to the various formats required by various BTS types.
7. A method and system as recited above, wherein the BTSs with co-located
LMUs receive a synchronization signal with little or no hardware cost, and
wherein BTS
sites not equipped with an LMU are equipped with TMU that has the single
function of
providing BTS time signals in the same formats as provided by the LMUs,
wherein the
time signals provided by the TMUs are synchronized to the signals provided by
the
LMUs and the timing-only TMU has a lower cost than the LMU because it does not
support uplink or downlink signal measurement functions.
[0004a] Provided herein, in a network overlay wireless location for a wireless
communications system comprising a network of Base Transceiver Stations, BTSs
(104),
is a method of improving spectrum, comprising synchronizing a plurality of
BTSs (104)
with timing signals, wherein the at least one BTS (104) is provided with a
respective
timing signal from a Location Measurement Unit, LMU (200A), said LMU having
uplink or downlink signal measurement functions for wireless location
measurement,
said LMU comprising a GPS-based timing reference module (202A) for generating
a
timing reference signal and means for generating the respective timing signal
including
the timing reference signal; wherein at least one BTS (104) is provided with a
respective
timing signal from a Timing Measurement Unit, TMU, having the single function
of
providing said respective timing signal, said TMU comprising a GPS-based
timing
reference module for generating a timing reference signal and means for
generating the

2


CA 02595365 2012-11-07

respective timing signal including the timing reference signal, wherein the
timing signal
provided by the TMU is synchronous to the timing signals provided by the LMU
and the
TMU lacks uplink or downlink signal measurement functions; and wherein the
respective timing signals for synchronizing said plurality of BTSs (104) are
provided by
one of a LMU (200A) and TMU and wherein the respective timing signals
generated by
the one of LMU and TMU are each synchronized within a pre-specified degree of
accuracy with the timing signals generated by the other of LMU (200A) and TMU.
10004b1 Also provided herein is a network overlay wireless location system for
a wireless communications system, said wireless communications system
comprising a
network of Base Transceiver Stations, BTSs, said wireless location system
comprising:
synchronizing means for synchronizing a plurality of BTSs with timing signals,
said
synchronizing means including: a Location Measurement Unit, LMU provided in at
least
one BTS, said at least one BTS being provided with a respective timing signal
from the
LMU, said LMU having uplink or downlink signal measurement functions for
wireless
location measurement, said LMU comprising a GPS-based timing reference module
for
generating a timing reference signal and means for generating the respective
timing
signal including the timing reference signal; a Timing Measurement Unit, TMU,
provided in at least one BTS, said BTS being provided with a respective timing
signal
from the TMU, said TMU having the single function of providing said respective
timing
signal, said TMU comprising a GPS-based timing reference module for generating
a
timing reference signal and means for generating the respective timing signal
including
the timing reference signal, wherein the timing signal provided by the TMU is
synchronous to the timing signals provided by the LMU and the TMU lacks uplink
or
downlink signal measurement functions; and wherein the respective timing
signals for
synchronizing said plurality of BTSs are provided by one of a LMU and TMU and
wherein the respective timing signals generated by the one of LMU and TMU are
each
synchronized within a pre-specified degree of accuracy with the timing signals
generated
by the other of LMU and TMU.
100051 It should be noted that the concept of the time signals being
"synchronized" is not limited to signals of substantially identical shape or
occurring
simultaneously. For example, two signals may be considered sufficiently
synchronized,
for the purposes of the present invention, where they are offset in time but
have a known
relationship.

BRIEF DESCRIPTION OF THE DRAWINGS
100061 Figure 1 schematically depicts and illustrative embodiment of an
emergency-only overlay location solution.

2a


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WO 2006/088472 PCT/US2005/014188
[0007] Figure 2 depicts several ways of deploying base station
synchronization products (LMUs and TMUs) in accordance with the present
invention.
[00081 Figure 3 depicts an illustrative embodiment of a TMU's internal
architecture and external interface.
[0009] Figure 4 depicts an illustrative relationship between a 1 PPS timing
signal and synchronization data.
[0010] Figure 5 depicts an exemplary GSM/UMTS network including a
mixture of synchronized/location-enabled BTSs and synchronized/not location-
enabled BTSs.
[0011] Figure 6 depicts an exemplary architecture of an External Interface
Unit (EIU).

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
1. Overview
[0012] The present invention is particularly suited for use in connection with
a network overlay solution for a GSM communications network. The GSM network
is
specified by the European Telecommunications Standards Institute (ETSI) and
extended by the 3rd Generation Partnership Project (3GPP). In a fully
integrated,
GSM specification-compliant Location Services solution, the SMLC (Serving
Mobile
Location Center) depends on the existing BSC (Base Station Controller) or PCU
(Packet Control Unit) to provide RF assignment information for the MS (Mobile
Station, i.e., the mobile unit to be located). By modifying the LMU to monitor
the
uplink and or downlink control channels, it is possible to implement an
emergency-
only overlay location solution that satisfies the FCC's E911 mandate and does
not
require any modifications to the existing GSM handsets or network. An
exemplary
architecture for such a solution is illustrated in Figure 1. (For further
information
about this architecture, see U.S. Patent Application No. 20040203429, filed on
September 3, 2002 and published on October 14, 2004, "E911 Overlay Solution
for
GSM, for Use in a Wireless Location System.")
[0013] As shown in Figure 1, the E911 overlay solution comprises the
following elements:
1. A GSM communications network 100, including receive/transmit
antennae 102A coupled to a Base Transceiver Station (BTS) 104; a Base Station
3


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WO 2006/088472 PCT/US2005/014188
Controller (BSC) 106; a Mobile Switching Center (MSC) 108; and a Gateway
Mobile
Location Center (GMLC) 110. All of these components and subsystems are well
known in the art. See, e.g., 3GPP TS 03.71 V8.6.0 (2002-06).
2. A Location Measuring Unit (LMU) 200A, which as indicated by the
dashed line may be co-located with the BTS 104, so as to share antennae 102A
for
receiving RF signals from the Mobile Stations. The LMU 202A may include an
internal GPS receiver and so a GPS antenna 202A may also be provided. The LMU
may also provide the ability to monitor and demodulate the forward channel
signals
transmitted by the BTS to the MS. This forward link monitor port may be
connected
to a separate antenna, or directly to the BTS forward link path. In addition,
the system
may be configured such that, for a given call, there will be a Primary LMU, in
this
case LMU 200A, and one or more Cooperating LMUs, e.g., the LMU designated
200B. The Cooperating LMUs are generally configured the same as the Primary
LMU, and so they are coupled to a GPS antenna 202B and are typically co-
located
with a BTS.
3. The LMUs are coupled to a Serving Mobile Location Center (SMLC)
300, which in turn is coupled to a Gateway Mobile Location Center (GMLC) or
Mobile Positioning Center (MPC) 400. The concept of the LMU, SMLC, GMLC, and
MPC are well known, as can be seen from the above-cited GSM specification
documents.
4. Figure 1 also shows a Mobile Station 500. Of course, there will
typically be many such units in operation within a geographic region, and more
than
one may be engaged in an emergency call at a given time.

[0014] In a cellular/wireless system, such as GSM or UMTS system,
spectrum utilization can be made far more efficient by synchronizing the BTSs.
For
example, 10-20% more voice calls per unit bandwidth can be achieved through
BTS
synchronization. Synchronizing a large number of BTSs in a network to an
adequate
level of accuracy is difficult and requires distributing a timing signal to
all BTSs, or
installing a satellite-based timing unit in each site. Satellite-based timing
units are
expensive and take up precious power and space at the BTS sites.
[0015] The present invention provides an architecture in which Location
Measurement Units (LMUs) are installed at some or all of the BTS sites for the
purpose of locating wireless devices. The LMUs are used to measure the timing
of

4


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WO 2006/088472 PCT/US2005/014188
various uplink and/or downlink signals in the cellular network in support of
various
location techniques. These LMUs may include a GPS-based timing reference
module,
which is used to synchronize the time bases of all LMUs. This allows relative
time
difference measurements to be made in support of location.
[0016] To reduce the overall cost of BTS synchronization, the LMU
distributes timing signals, including a periodic electrical pulse as well as
time
description information, on a serial or other interface, which is available
for other
nodes to use for synchronization. The format of the electrical pulse and time
description information is modified through hardware and software to adapt to
the
various formats required by various BTS types. For example, the BTSs with co-
located LMUs can receive a synchronization signal with little or no hardware
cost.
The EI[J described later is used to adapt to various BTS hardware formats.
[0017] Not all BTS sites will be equipped with the LMUs. For those sites
without an LMU, a Timing Measurement Unit (TMU) can be used. The TMU has the
single function of providing BTS time signals in the same formats as provided
by the
LMUs. The time signals provided by the TMUs are synchronous to the signals
provided by the LMUs. This timing-only TMU has a lower cost than the LMU
because it does not support the uplink or downlink signal measurement
functions.
This set of products allows a cellular operator (wireless carrier) to
synchronize the
BTSs at a relatively low cost.

2. BTS Synchronization
[0018] In accordance with the present invention, the LMUs may contain a
high performance GPS receiver to provide a common high accuracy timing
reference
for all LMUs within the location system. The GPS receiver can provide a timing
reference to a co-located base station for the purposes of synchronizing the
base
station network, i.e., to synchronize the BTSs to within a specified degree of
precision. In one exemplary implementation of the invention, the LMU contains
a
network synchronization interface that may be adapted to be compatible with
the
corresponding interface on the associated BTS. Thus, through the addition of
software
modifications, the existing LMUs can be upgraded to a configuration compatible
with
the BTS interface. This software upgrade is termed the BSS Timing Option
(BTO),
and can be installed into existing LMU/ BTS installations and shipped with new
LMUs.



CA 02595365 2007-07-19
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[0019] For BTS sites without an installed LMU, a Timing Measurement
Unit (TMU) may be employed. The TMU contains a GPS receiver and necessary
software to conform to the BTS timing interface. A market can contain a mix of
LMUs with BTO and TMU timing modules or the carrier may elect to use only the
TMU to synchronize markets where LMUs are not yet installed.
[0020] The Timing Measuring Unit is a standalone product that can be
deployed independent of the Wireless Location Systems. The TMU contains a
built-in
GPS receiver, including GPS antenna, for the purpose of establishing precise
timestamps. The clocking output includes a 1 pulse per second (PPS) signal and
timing information. The TMU provides data in a pre-specified ASCII format
developed for use with the particular BTS equipment deployed.
[0021] TruePosition base station synchronization products can be employed
in several ways, as recited below and depicted in Figure 2:
1. In green-field deployments which have neither location nor
synchronization capability.
2. When upgrading an already synchronized BTS to include location
capability.
3. When upgrading a location-enabled BTS to incorporate
synchronization.

3. Timing Measurement Unit (illustrative embodiment)
[0022] To enable synchronized GSM operation by the wireless carrier, a
TMU can be deployed to provide a periodic signal and related timing data
information
to the BTSs. The TMU preferably includes a GPS receiver designed to provide
this
periodic signal and related timing data information to the BTS over, e.g., an
RS-422
communications interface.
[0023] In one exemplary embodiment, the TMU is a standalone device
containing a GPS receiver/engine (GPS), an 80C51 microcontroller (C51), a
serial
interface for supplying timing information to a BTS, and a console interface.
The
purpose of the TMU is to obtain accurate time information from the GPS and
supply
it to the BTS. Timing is provided to the BTS in the form of a pulse per second
(PPS)
signal that is preceded by a serial message announcing the precise time at the
rising
edge of the pulse.

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[0024] The TMU attempts to maximize the amount of time that it can supply
accurate timing information to the BTS. To this end, the TMU takes measures to
bring
the GPS on-line as quickly as possible after a power outage and to keep it on-
line

whenever possible.
[0025] To support maintenance and test, the TMU has three modes of
operation, boot mode, test mode and operational mode. Boot mode allows the TMU
firmware to be updated after production. Test mode supports testing and
diagnostics
of the TMU hardware platform. Operational mode provides the primary TMU
functionality of supplying timing to the BTS.
[0026] The TMU provides synchronization information as described above
for two primary reasons:
1) When an LMU is not present in the BTS. When an LMU is present,
synchronization information is provided by the LMU through an External
Interface Unit (EIU). The External Interface Unit takes the 1 PPS signal and
related timing information signal and converts both signals to an RS-422
communication format for interface to the BTS.
2) When an LMU is deployed with equipment already utilizing its signal
output capability, such that is it unable to provide the timing signals.
[0027] Figure 3 shows an illustrative embodiment of the TMU internal
architecture and external interfaces. The received GPS satellite signal is
input to the
TMU internal GPS receiver. An internal micro-controller provides the following
capabilities:
1) Format GPS timing data in a serial format as may be required.
2) TMU firmware upgrade through the external RS-232 Console port.
3) Control the tri-colored LED that indicates TMU health, and synchronization
status.
4) Reset capability through a front panel reset switch.

[0028] The 1 PPS signal output from the GPS receiver, and the formatted
serial timing data signal output from the micro-controller are both converted
to RS-
422 signal levels, and output to the BTS. The 1 PPS and serial data signals
are fanned
out to 4 four ports that comprise a quad output connector. Each output port
provides
both a 1 PPS and a serial data output in RS-422 signal levels.

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[0029] The TMU micro-controller firmware is capable of upgrade through
the RS-232 console port.
[0030] The TMU will transmit the synchronization timing data messages,
and the 1PPS signal to the BTS in RS-422 signal levels as shown in Figure 3.
The
synchronization timing data interface to the BTS may be a serial
communications
link.
[0031] The 1 PPS signals distributed by the TMU at each of the 4 output
ports may have a frequency of 1 Hz and an accuracy 100 ns RMS with respect to
UTC time.
[0032] The serial communications link physical layer is based on a RS-422
UART. Specific characteristics are as follows:

= RS-422 interface with 100 ohm termination in the BTS
= 9600 bits/s

= No parity

= One start bit

= 8 bits data length
= One stop bit

[0033] A RS-422 transmitter in the TMU drives the one PPS signal. The 10
- 90 % rise time may be less than 10 ns at each of the TMU output ports. The
BTS
may include a built in 100 ohm termination.
[0034] The synchronization data is preceding the one PPS pulse. See Figure
4 for timing details. The arrows in Figure 4 show the rising edge of the PPS
pulse-
pulse. The data signal containing the timing information is preceding the
corresponding PPS-pulse.
[0035] Figure 5 is a schematic diagram showing a GSM or UMTS network
in which the BTSs are synchronized using the timing information obtained from
an
LMU or a TMU. The LMUs may or may not require an ElU, depending on the BTS
interface requirements as discussed herein.

TMU Operational Description (illustrative embodiment)
[0036] As discussed, the TMU provides timing for a BTS that will enable
the BTS to synchronize its operation with other BTSs in its network. The TMU

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derives timing information from its integral GPS receiver and provides the BTS
with
a PPS signal and Periodic PPS Report and Position Data messages. The TMU is
deployed at locations where there is no LMU present or where timing signals
are
unavailable from the deployed LMU. Where the LMU is deployed, the LMU can
supply the same timing functionality as the TMU by employing an EIU.
Synchronized
BTSs can increase network capacity through precise management of radio
resources.
[0037] The TMU software, in a preferred implementation, supports three
modes of operation: boot mode, test mode and operational mode. Although each
mode
provides a mechanism that allows switching to the others, each mode is
independent
and mutually exclusive. That is, boot mode does not support test mode
functionality,
test mode does not support boot mode functionality, neither boot nor test mode
provide any operational functionality, and operational mode does not support
any
functionality of the other two modes.
[0038] To utilize the functionality of any mode, the TMU must first be
switched to that mode by an appropriate mechanism (usually a console command).
Once switched into a particular mode, it is understood that the functionality
of the
other modes is unavailable. For example, when switched to test mode, the time
synchronization to the BTS is disabled since this functionality is only
supported by
operational mode. BTS timing synchronization cannot be resumed until the TMU
is
returned to operational mode.
[0039] Certain conditions can prevent the switching from one mode to
another. For example, it is not possible to switch out of boot mode if a valid
program
image is not present. In addition, certain conditions can cause an automatic
switch to a
mode. For instance, the TMU will automatically switch to boot mode on reset if
a
valid program image is not present.
[0040] The current mode of the TMU may be identified by the console
prompt. The console prompt enumerates the current mode as follows.
= "TMU>" for operational mode
= `Boot>" for boot mode

= "Test>" for test mode

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Boot Mode
[0041] Boot mode allows the TMU software to be update in the field. In
boot mode, a software image can be downloaded through the console port. The
downloaded image will replace the image stored in flash memory. Only the test
mode
and operational mode portions of the image can be replaced using this method.
The
boot mode portion of the image can only be replaced during production or
through a
JTAG port.
[0042] Boot mode may be entered by console command or it may be
automatically invoked following a reset if a valid program image is not found.
Certain
failure conditions, such as a watchdog timeout, can produce a reset that may
then
result in the boot mode being invoked. Boot mode is exited by a reset when a
valid
program image is present. Reset can be implemented by pushing the reset
button,
cycling power or by console command. Boot mode cannot be exited if a valid
program image is not present. When boot mode is exited successfully, the TMU
returns to the operational mode.

Test Mode
[0043] Test mode supports console commands that directly exercise the
TMU hardware. Commands are generally either low-level commands or high-level
commands. Low-level commands directly manipulate TMU hardware and provide
little or no translation for the operator. Low-level commands are useful for
board-
level test and troubleshooting. High-level commands provide signal
interpretation and
manipulate combinations of signals to support interaction with the hardware by
the
operator. These commands are useful when diagnosing operational issues.
[0044] Test mode is intended for use during manufacturing testing,
installation, diagnosing of field failures and repair. Test mode is intended
for use by a
trained technician. Test mode may be entered from operational mode by console
command. Test mode is exited by any reset and the TMU returns to the
operational
mode (as long as a valid program image is present).

Operational Mode
[0045] Operational mode is the primary mode for the TMU. When in
operational mode, the TMU functions autonomously toward its primary goal,
supplying precise time synchronization information to the BTS. While in
operational



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mode, the TMU may send alarms and status information to the console port. In
addition, operational mode supports console commands that allow query of
operational conditions and manipulation of operational parameters.
[0046] Operational mode is entered automatically following any reset, if a
valid program image is present. Operational mode may be exited by invoking
test
mode or boot mode via console command. Operational mode may be exited
automatically if certain failure conditions are detected.

Operational States
[0047] The TMU's front panel status LED reflects the TMU's current state.
The state of the TMU is determined by its mode of operation and the exiting
conditions. Of the ten (10) possible LED states, only the following are
defined as
valid. LED states always indicate existing conditions.

= SOLID RED (failure) - This indicates a failure, such that the TMU is unable
to function normally and must be replaced or repaired by a qualified
technician.
= FLASHING GREEN (initializing) - This indicates that the TMU is
operational and no unexpected conditions have been detected. This state may
only exist immediately following reset and indicates that the conditions
necessary to provide timing to the BTS have not yet been established. If the
required conditions cannot be established within two minutes following reset,
the state will proceed to FLASHING AMBER. Once this state has been
exited, the TMU will not return to this state until it is again reset

= SOLID GREEN (full functionality) - This indicates that the TMU is
operating normally, there are no outstanding alarm conditions, and the BTS is
being supplied with accurate timing.

= FLASHING AMBER (impaired) - This indicates the TMU is completely
functional but that there exist conditions or alarms that prevent the TMU from
supplying the BTS with timing. This state is always the result of external
influences, such that replacing the TMU itself will not circumvent the issue.
When all outstanding conditions clear, the TMU will return to the SOLID
GREEN state.

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Alarms and Status Messages
[00481 In operational mode, the TMU monitors conditions that may affect its
ability to provide accurate timing information to the BTS. In addition, it
also notes
exceptions or conditions that it encounters in the execution of its
programming.
Messages concerning these conditions will be sent to the console. These
messages are
either alarms or status. A status message is purely informative and can
indicate
anything of interest. The issuance of a status message has no effect on the
TMU.
Alarms indicate conditions that may impact the performance of the TMU. The
existence of alarms may result in a change of the TMU state. When multiple
alarms
are indicated, the most severe state is assumed.

Table 1 - TMU Alarms
No. Alarm State De9c'ript on
1 CPU clock failure Solid Red The CPU external oscillator is not functioning
Raised: During software initialization
Cleared: Only be reset
Indication to BTS:
No messages
2 TMU Initialization Solid Red The TMU CPU has encountered an error during
failure initialization
Raised: During software initialization
Cleared: Only be reset
Indication to BTS:
No messages
OR
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (1) GPS Receiver Faulty
3 GPS not detected Solid Red The CPU is unable to detect the presence of GPS.
The
GPS is assumed to be totally nonfunctional
Raised: During software initialization if GPS
fails to respond to initialization procedures
Cleared: Only by reset
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (1) GPS Receiver Faulty
4 GPS comm. failure Solid Red The CPU is experiencing difficulty in
communicating
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No. Alarm State Description
with the GPS to the extent that the CPU is unable to
control the GPS or to obtain the information necessary
for the mandatory BTS reports
Raised: The first time that a mandatory BTS report
cannot be completed due to GPS communications
Cleared: The first time that a mandatory BTS report is
successfully accomplished
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (1) GPS Receiver Faulty
GPS Internal Failure Solid Red The GPS self-test has reported a failure of the
GPS
ROM and/or RAM. GPS self-test is run following CPU
reset.
Raised: Based on the self test results
Cleared: Only by reset
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (1) GPS Receiver Faulty
6 GPS No satellites Flash Amber There are no satellites available to the GPS
receiver.
(Flash Raised: When the No. of satellites used for positioning
Green) of the GPGGA sentence indicates 0
Cleared: When one or more satellites are indicated
Indication to STS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (0) GPS Receiver running
7 GPS PPS Not available Flash Amber The GPS indicates that the PPS will not be
output.
(Flash Raised: When the PPS Availability Status field of the
Green) GPTps sentence indicates "PPS not output"
Cleared: When PPS output is indicated
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (0) GPS Receiver running
8 GPS No UTC Parameter Flash Amber The UTC parameter has not been obtained and
PPS
(Flash accuracy cannot be ensured.
Green') Raised: When the Date/Time of UTC Parameter field of
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No:: Alarm State Description
the GPTps sentence indicates "000000000000"
Cleared: When a valid date/time stamp is indicated
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (0) GPS Receiver running
9 GPS Time Not valid Flash Amber The GPS time has not been determined.
(Flash Raised: When the Validity Flag field of the GPgpt
Green) sentence indicates "GPS Time not determined yet"
Cleared: When "GPS Time valid" is indicated.
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (0) GPS Receiver running
GPS Position Mode, Not Flash Amber The GPS indicates that the position data is
not valid.
valid (Flash Raised: When the Position System Mode Indication
Green) field of the GPGLL, GPRMC or GPVTG sentence
indicates "Data not valid" or The GPS Quality
Indication field of the GPGGA sentence indicates "0:
Fix not available or invalid"
Cleared: When "Autonomous mode" or "Differential
mode" is indicated
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (0) GPS Receiver running
11 PPS not detected Flash Amber Information from the GPS indicates that the
PPS is
(Flash being generated, but the PPS is not detected by the
Green') CPU.
Raised: When PPS output is expected and PPS is not
found for 2 seconds
Cleared: When a PPS is detected
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (0) GPS Receiver running
12 GPS Navigation receiver Flash Amber The GPS indicates a Navigation receiver
warning in the
warning (Flash Status field of the GPGLL, GPRMC, or GPRMC
Green) sentences.

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No. Alarm State Description

Raised: When "Nav receiver warning" is indicated
Cleared: When "Data Valid" is indicated
Indication to BTS:
GPSS Status = (3) PPS not Synchronized
GPSS Faulty = (0) GPS Receiver running
13 GPS Sats less than 4 Solid Green The No of satellites used for positioning
field of the
GPGGA or GPGSA sentence indicates that less than 4
satellites are available.
Raised: When 1,2 or 3 satellites are indicated
Cleared: When 4 or more satellites are indicated
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
14 GPS PPS TRAIM Alarm Solid Green TRAW is available and indicates a problem
with the
PPS timing.
Raised: When the PPS Output Result Status field of the
GPrrm sentence is "1"
Cleared: When the a value other than "1" is indicated
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
15 GPS Antenna Failure Solid Green The GPS self-test has reported a failure on
the GPS
antenna connection. GPS self-test is run following CPU
reset.
Raised: Based on the self-test results
Cleared: Only by reset
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
16 GPS Position Mode, Solid Green The GPS is operating in stand-alone mode.
Autonomous Raised: When the Position System Mode Indication
field of the GPGLL, GPRMC or GPVTG sentence
indicates "Autonomous mode"
Cleared: When "Autonomous mode" is not indicated
Indication to BTS:



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No. Alarm State Description
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
17 GPS Position Mode, Solid Green The GPS is operating in differential mode.
Differential Raised: When the Position System Mode Indication
field of the GPGLL, GPRMC or GPVTG sentence
indicates "Differential mode"
Cleared: When "Differential mode" is not indicated
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
18 GPS DGPS not received Solid Green The GPS is not receiving DGPS data.
Raised: When the DGPS status field of the GPdie
sentence is "0"
Cleared: When the DGPS status field of the GPdie
sentence is non-zero
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
19 GPS DGPS base station Solid Green The GPS is receiving DGPS information but
the DGPS
unhealthy base station is unhealthy, the GPS will operate stand-
alone
Raised: When the DGPS Base station's Health
Condition field of the GPdie sentence indicates
"unhealthy"
Cleared: When "healthy" is indicated
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
20 GPS DGPS Data Solid Green The GPS is receiving DGPS information but the
DGPS
Abnormal data is bad, the GPS will operate stand-alone
Raised: When the DGPS Data Status field of the GPDie
sentence indicates "Abnormal"
Cleared: When "Normal" is indicated
Indication to BTS:
GPSS Status = (0) PPS Locked
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No.' Alarm State Description

GPSS Faulty = (0) GPS Receiver running
21 GPS DGPS Error Solid Green The GPS indicates that an error associated with
the
DGPS.
Raised: When the DGPS Error Code field of the GPdie
sentence is other than "0"
Cleared: When "0" is indicated
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
22 GPS TRAIM Detection Solid Green TRAIlVI is available but there are only
enough satellites
Only to detect alarm conditions, deletion of abnormal
satellites is not possible
Raised: When the TRAIM Status field of the GPrrm
sentence is "1"
Cleared: When the value is other than "I"
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
23 GPS TRAM Not Solid Green TRAIM is not available
Available Raised: When TRAIM Status field of the GPrrm
sentence is "2"
Cleared: When the value is other than "2"
Indication to BTS:
GPSS Status = (0) PPS Locked
GPSS Faulty = (0) GPS Receiver running
Operational Processes
[0049] This section describes the procedures followed by the illustrative
TMU software. With the exception of the some of the initial startup
processing, all
procedures refer to operational mode.
Startup
[0050] The startup procedure is performed following any reset of the C51.
The purpose of the startup process is to bring up the platform and establish
an
operational state. The startup procedure also performs a self-check of the TMU

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platform and a software integrity test. If the software integrity test fails,
the TMU
enters boot mode.
Establish C51 Control
[0051] The first part of the startup procedures establishes the operation of
the C51 and configures 110 for control of the TMU platform.
1. Check for the presence of a software image.
2. Check the integrity of the software image.
3. Configure the C51 1/0 mapping
4. Disable PPS and Serial output to the BTS.
5. Configure the LED drive.
6. Check and switch to the external oscillator.
7. Configure the serial communications ports
Establish Control of the GPS
[0052] The second part of the startup procedure establishes control of the
GPS. When establishing control of the GPS, the TMU may perform either a warm
or
a cold restart. A cold restart assumes that the GPS engine must be completely
reinitialized and that all previous information is lost. Under these
conditions, several
minutes may be required before timing can be reestablished. A warm restart
attempts
to reestablish timing sooner by preserving the information stored in GPS. This
is
possible because the GPS is an independent subsystem of the TMU. Under some
conditions, such as a button reset, the C51 is reset but the GPS is not. In
addition,
since no power interruption was experienced, the GPS is still operating
normally. In
these cases, a warm restart reestablishes control of the GPS without
disrupting its
operation.
[0053] A cold restart of the GPS will be performed if any of the following
conditions exist, otherwise, a warm restart will be attempted.

= The C51 experienced a power-on-reset.
= A hard self-reset was commanded.

= The GPS does not respond to communications.
= The GPS self test indicates an error.
= The reset button was pushed while the LED state was other than SOLID
GREEN.

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Cold Restart
[0054] A cold restart of the GPS involves the following steps.
1. Give the GPS a hard reset by asserting its reset signal line.
2. Send the $PFEC,GPclr,1 command.
3. Stop all periodic report messages.
4. Perform a Sef-Test.
5. Configure timing for periodic messages.
6. Configure PPS delay due to cable length.
7. PPS Control Mode is set to be output always.
8. Proceed to establishing position.
Warm Restart
[0055] A warm restart of the GPS involves the following steps.
1. Give the GPS a hard reset by asserting its reset signal line.
2. Send the $PFEC,GPclr,2 command.
3. Stop all periodic report messages.
4. If GPS fails to return response messages, perform Cold Restart.
5. Perform a Self-Test.
6. If Self-Test indicates that backed up data is bad, perform Cold Restart.
7. Configure timing for periodic messages.
8. Configure PPS delay due to cable length.
9. Configure PPS Control Mode to be output always.
10. Proceed to establishing position.
Establishing Position
[0056] Once the TMU has established control of the GPS, its next objective
is to establish its position. The GPS must determine its position before it
will be able
to produce accurate time information. Following a warm restart, the TMU checks
the
GPS to determine if the position is already known and fixed (fixed observation
mode)
by the GPS. If the position is both known and fixed, the TMU reads the
location from
the GPS and proceeds as normal. If the position is known but not fixed, the
TMU
reads the location and proceeds with self-survey as described in the next
section. If the
position is unknown (or for the case of a cold start), the TMU proceeds with
establishing its position.
[0057] The TMU can obtain its position information (latitude, longitude and
altitude) from one of three sources, console input, nonvolatile memory or self-
survey.
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The TMU stores its last known location in its nonvolatile memory. To determine
its
current position, the TMU sets the GPS to the estimated observation mode and
sets
the initial position to its last know location. The TMU then proceeds with
self-survey.
[0058] A position can be entered manually via console command. If this is
done, the location replaces the location data stored in the nonvolatile
memory, the
GPS is set to the estimated observation mode and the specified location data
is written
to the GPS as the initial position. The TMU then proceeds with self-survey.
[0059] When position is unknown, there is no last location stored, and there
is no console input, the TMU relies completely on the self-survey process. In
this
case, the GPS is set to the estimated observation mode, and the last known
location is
used as the initial position. The self-survey process is then allowed to
correct the
location information. If the last known location is very far from the actual
location, it
may require an extended amount of time for the TMU to establish its time
synchronization.
Self Survey
[0060] The TMU utilizes the self-survey process to determine its exact
position and, thereby, produce the most accurate timing. To determine
location, the
TMU places the GPS into the estimated observation mode. In this mode, the GPS
will
determine its location from the satellites that it can observe. While
performing
self-survey, the TMU will periodically read the location data from the GPS and
compute an average location. Note that self-survey does not prevent the TMU
from
outputting time synchronization information once an initial location has been
established by the GPS. The self-survey process will continue for up to12
hours. At
the completion of the self-survey period, the GPS will be set to the fixed
observation
mode and the average location computed will be set. The location determined by
self-
survey will replace the last known location stored in the TMU nonvolatile
memory.
Position Averaging
[0061] While performing self-survey, the TMU obtains the estimated
location information once each minute in the $GPGGA message. The TMU
implements independent averages for longitude, latitude and altitude
parameters. The
TMU implements a majority-voting algorithm on the integer portion of each
parameter and an averaging of the fractional portion. The integer portion of
latitude
and longitude includes degrees and integer minutes. The integer portion of
altitude is



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the whole 100s of meters. The fractional portion is the fractional minutes of
latitude

or longitude and altitude modulo 100.
[0062] For integer portions, the majority-voting algorithm observes the
current reported value; the two previously reported values and the last known
location
(LKL) value. If the integer portion of the three reported values agrees with
each other
but disagree with the LKL, the LKL is discarded and replaced with the agreed
integer
portion. For example, if the integer portion of the three most recent latitude
values
agree but disagree with the LKL, the integer portion of the LKL is replaced
with the
agreed upon value. The fractional portion of the LKL is replaced with the
average of
the fractional portion of the consenting values.
[0063] If the integer portion of all four values agrees, the fractional
portion
of the newest value is averaged into the LKL. If all values, except the newest
value
agree, the fractional portion of the newest value is not averaged into the
LKL. The
fractional portion is computed by a straight average of all of the
contributions since
the last time the LKL was replaced.
[0064] The majority-voting algorithm helps to protect the average from the
influence of anomalous locations. Additional rules or algorithms may be
employed in
determining the stability of the location average and allow a more rapid
change to
fixed position mode.
Last Known Location
[0065] The TMU stores its last known location in its nonvolatile memory.
This location is utilized to hasten the establishment the GPS time output. To
minimize
the wear on nonvolatile memory, the value will be updated only on one of the
following conditions.
= When a manual location is entered via console command.
= On completion of the self-survey processing.
= Whenever, the self-survey average differs from the stored location by more
than 1/100 minute of latitude or longitude, or more than 10 meters of
altitude.
Antenna Cable Length
[0066] The length of the cable to the GPS antenna can affect the accuracy of
the PPS. The TMU requires that this value be entered manually during
installation.
The POSITION console command is provided for this purpose. The cable length
will

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be stored to non-volatile memory and will be utilized every time the GPS is
configured.
Initiating Output to BTS
[0067] The TMU configures the GPS to begin output of timing data
immediately. The TMU configures the GPS to begin outputting the PPS signal
immediately. If the GPS is in the fixed observation mode, the PPS will be
accurate for
as long as one satellite is available. If the GPS is in the estimated
observation mode,
the PPS will become accurate when 4 satellites are available to fix the
position, the
UTC parameter is available, ephemeris data for satellite is available, and the
UTC
computation completes.
[0068] The TMU will begin sending the Periodic Pulse Report (GPppr) and
the Position Data Report (GPGGA) to the BTS immediately after initialization.
As
soon as the PPS signal is available from the GPS, the TMU will begin sourcing
the
PPS signal to the BTS as well. However, the GPSS Status field of the GPppr
will
indicate "PPS Not synchronized" until all alarm conditions in the above table
marked
Flash Green are clear.
Supporting Greater Timing Accuracy
[0069] The TMU attempts to support the greatest possible timing accuracy
by allowing the GPS to utilize its DGPS and TRAIM features. These features are
enabled by default.
Synchronization Loss
[0070] Once timing output has successfully commenced, the occurrence of
any critical alarm will cause the GPSS Status field of the GPppr to indicate,
"PPS Not
synchronized" until the condition clears.
BTS Messages Supported
[0071] The TMU supports only the messages that are mandatory. In.
addition, only the mandatory fields within these messages are supported. These
messages are:
1. Periodic PPS Report
2. Position Data Report
Periodic PPS Report ($PTP,GPppr)
[0072] The GPS TOW Standard Deviation field of the Periodic PPS Report
will be populated as follows.

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= If 5 or more satellites used for positioning, the field will be set to
50nsec

= If 4 or less satellites are used for positioning, the field will be set to
100nsec
= If no satellites cause are available, the GPS Status field will be set to
(3) PPS
not synchronized
Position Data (&GPGGA)
[0073] The optional fields; DGPS Data Time, DGPS Station ID and the
checksum will not be provided. The fields; DOP, Geoid of Altitude, and Unit of
Geoid
are set to a blank.

Console Port Operation
[0074] The console port allows human interaction and monitoring of the
TMU through an ASCII terminal or terminal emulation software. Following reset
or
by entering escape at the command prompt, the console interface enters status
display
mode. In this mode, alarms and other event driven status strings are sent to
the
console. The console can collect these strings to monitor the operation and
health of
the TMU.
[0075] When the enter key is pressed while in status display mode, the
console interface changes to command entry mode and issues the command prompt.
The command prompt reflects the current mode of TMU operation; boot, test or
operational. Commands may then be entered and the results will be sent to the
console. All spontaneous alarm and status string output will be inhibited
while in
command entry mode.
[0076] The commands available are limited by the TMU's mode of
operation. An operator may change modes to obtain access to the desired
commands.
The operator should be aware of the consequences of invoking any TMU mode of
operation.

4. External Interface Unit (EIU) (illustrative embodiment)
[0077] As discussed, to enable synchronized GSM operation, a 1 PPS signal
may be provided to the BTSs. For sites that already have an LMU deployed with
them, the 1 PPS signal may already be available on those existing LMUs (since
the
LMUs include built-in GPS receivers). However, for certain types of BTS
equipment,
the following may be true:

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= The 1 PPS signal needs to be converted to RS-422 signal levels for this
application.
= In addition to the 1 PPS conversion, the timing information related to I PPS
signal also needs to be sent over the RS-422 interface using the proprietary
protocol called for by the BTS equipment manufacturer (e.g., Ericsson).
[0078] The protocol conversion hardware unit that performs these two
operations is called an EIU and is applicable to those cell sites that already
have an
LMU deployed there.
Impact on GBE and mE-board connectivity
= The ER] will be connected to the 9-pin RS-232 serial port on the LMU. This
is
the same port that is also used to connect the GBE (ground based electronics)
in AOA deployments. Hence, in their present forms the GBE and EIU cannot
be co-deployed. Therefore, installation of EIU precludes AOA deployment.
The solution to this problem is to use a TMU instead of an EIU in cases where
AOA is needed.
= Similar to the above problem is the case of using the environmental board
(which is sometimes called the mini environmental board, or mE-board). It
also uses the same port and cannot be deployed where an Eli] is used.
Architecture
[00791 An exemplary architecture for an ER J is depicted in Figure 6, which
shows the internal architecture and external interfaces of the EIU. It
connects to the 9
pin serial port and the 1 PPS on the LMU side, and converts both of these
interfaces to
RS-422 signal levels for connection with the BTS. The 1 PPS and serial data
signals
are fanned out to 4 four ports that comprise a quad output connector. Each
output port
provides both a 1 PPS and a serial data output in RS-422 signal levels.

LMU-N Interface
[0080] The illustrative ElU receives timing messages from its LMU
interface in RS-232 signal format/levels. The RS-232 signal connection pin
outs will
24


CA 02595365 2007-07-19
WO 2006/088472 PCT/US2005/014188
be as shown in table 1. The EIU receives the 1 PPS signal from the LMU through
its 1
PPS port. The 1 PPS ETU port appears as a 50-ohm load from outside.

Pin Signal Name Description
1,7,8,9 NC
2 RX Port 1 Receive, from the PC to the
processor
3 TX Port 1 Transmit, from the processor
to PC
4 DTR Data Terminal Ready - from PC
GND Ground
6 DSR Data Set Ready
Table: RS-232 Connector Pin Outs

BTS Interface
[0081] The EIU transmits the LMU synchronization data messages and the
1PPS signal to the BTS in RS-422 signal levels as shown in Figure 4. The
synchronization data interface to the BTS is a serial communications link.
[0082] The 1 PPS signal will have a frequency of 1 Hz and an accuracy of
100ns RMS at the 1 PPS EIU output port with respect to UTC time.
[0083] The signal connection pin outs for each port will be as shown in the
table below.
Pin Signal Name Description
1 TX+ Transmit
2 TX- Transmit return
3 TX+ Transmit (optional)
4 1PPS Pulse Per Second
5 1PPS- Pulse Per Second Return
6 TX- Transmit return (optional)
7,8 NC
9,10 GND



CA 02595365 2007-07-19
WO 2006/088472 PCT/US2005/014188
Table: RS-422 Single Port Pin Outs

Serial Communications Link
100841 The serial communications link physical layer is based on a RS-422
UART. Specific characteristics are as follows:
= RS-422 interface with 100 ohm termination in the BTS
= 9600 bits/s

= No parity

= One start bit

= 8 bits data length
= One stop bit
One PPS
[0085] A RS-422 transmitter in the EIU drives the one PPS signal. The 10 -
90 % rise time will be less than 10 ns at the EIJ output. The BTS has a built
in 100
ohm termination.

5. Conclusion
[0086] The true scope the present invention is not limited to the illustrative
and presently preferred embodiments disclosed herein. For example, the
foregoing
disclosure of a Wireless Location System uses explanatory terms, such as LMU,
TMU, EIU, BTS, BSC, SMLC, and the like, which should not be construed so as to
limit the scope of protection of the following claims, or to otherwise imply
that the
inventive aspects of the Wireless Location System are limited to the
particular
methods and apparatus disclosed. Moreover, as will be understood by those
skilled in
the art, many of the inventive aspects disclosed herein may be applied in
location
systems that are not based on TDOA techniques. In such non-TDOA systems, the
SMLC described above would not be required to perform TDOA calculations.
Similarly, the invention is not limited to systems employing LMUs constructed
in a
particular manner, or to systems employing specific types of receivers,
computers,
signal processors, etc. The LMUs, SMLC, etc., are essentially programmable
data
collection and processing devices that could take a variety of forms without
departing
from the inventive concepts disclosed herein. Given the rapidly declining cost
of

26


CA 02595365 2007-07-19
WO 2006/088472 PCT/US2005/014188
digital signal processing and other processing functions, it is easily
possible, for
example, to transfer the processing for a particular function from one of the
functional
elements (such as the SMLC) described herein to another functional element
(such as
the LMU) without changing the inventive operation of the system. In many
cases, the
place of implementation (i.e., the functional element) described herein is
merely a
designer's preference and not a hard requirement. Accordingly, except as they
maybe
expressly so limited, the scope of protection of the following claims is not
intended to
be limited to the specific embodiments described above.
[00871 In addition, any reference herein to control channels or voice
channels shall refer to all types of control or voice channels, whatever the
preferred
terminology for a particular air interface. Moreover, there are many more
types of air
interfaces (e.g., IS-95 CDMA, CDMA 2000, and UMTS WCDMA) used throughout
the world, and, unless the contrary is indicated, there is no intent to
exclude any air
interface from the inventive concepts described within this specification.
Indeed,
those skilled in the art will recognize other interfaces used elsewhere are
derivatives
of or similar in class to those described above.

27

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date 2013-01-22
(86) PCT Filing Date 2005-04-25
(87) PCT Publication Date 2006-08-24
(85) National Entry 2007-07-19
Examination Requested 2009-11-06
(45) Issued 2013-01-22
Deemed Expired 2018-04-25

Abandonment History

There is no abandonment history.

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $400.00 2007-07-19
Maintenance Fee - Application - New Act 2 2007-04-25 $100.00 2007-07-19
Maintenance Fee - Application - New Act 3 2008-04-25 $100.00 2007-07-19
Maintenance Fee - Application - New Act 4 2009-04-27 $100.00 2009-04-03
Request for Examination $800.00 2009-11-06
Maintenance Fee - Application - New Act 5 2010-04-26 $200.00 2010-03-15
Maintenance Fee - Application - New Act 6 2011-04-25 $200.00 2011-04-04
Maintenance Fee - Application - New Act 7 2012-04-25 $200.00 2012-04-13
Final Fee $300.00 2012-11-07
Expired 2019 - Filing an Amendment after allowance $400.00 2012-11-07
Maintenance Fee - Patent - New Act 8 2013-04-25 $200.00 2013-03-19
Maintenance Fee - Patent - New Act 9 2014-04-25 $200.00 2014-03-12
Maintenance Fee - Patent - New Act 10 2015-04-27 $250.00 2015-04-01
Maintenance Fee - Patent - New Act 11 2016-04-25 $250.00 2016-03-30
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
TRUEPOSITION, INC.
Past Owners on Record
ANDERSON, ROBERT J.
BULL, JEFFREY F.
COHEN, BENJAMIN HERMAN
SHEEHAN, JOSEPH W.
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Abstract 2007-07-19 1 84
Claims 2007-07-19 4 164
Drawings 2007-07-19 5 98
Description 2007-07-19 27 1,317
Representative Drawing 2007-07-19 1 11
Cover Page 2007-10-11 1 59
Description 2012-11-07 28 1,357
Representative Drawing 2013-01-18 1 7
Description 2012-08-01 27 1,306
Claims 2012-08-01 2 88
Cover Page 2013-01-08 1 60
PCT 2007-07-19 3 161
Assignment 2007-07-19 4 123
Office Letter 2018-02-05 1 33
Prosecution-Amendment 2009-11-06 1 39
Prosecution-Amendment 2012-11-16 1 15
Prosecution-Amendment 2012-05-31 3 97
Prosecution-Amendment 2012-08-01 7 265
Correspondence 2012-11-07 2 71
Prosecution-Amendment 2012-11-07 4 179