Note: Descriptions are shown in the official language in which they were submitted.
WO 94/1077~ 2 1 ~ ~ 3 8 1 P~/US93/10~28
~ITLE. RAD:I:O F~EQ~ ~CY CO~NICAq!:EC)~
N13!1!110~ !; IIA~I~G ;~DAP!lrIVB
C~ICA~IO~I PA~!I~
..
BP~CR~;ROIJND C)F T~B INV~TION
The present invenkion in a pref erred
implementation relates to improv~ments in radio
data communication networks whereill a number of
mobile transceiver units are to transmit data to ~.
a n~er of base stzltions under a wide range of
l0 opera~ing conditions . To compensate f or the wide
range of operating con~îtion~;, adaptability has
been pro~rided using an exch2a~ge of parame~ers that
def ine the nature of th~ network ::ommunication . ::
- The in~entiQn is preferably to be appli~able as an
15 upgrade of an exis~ing data capture ~;ystem wherein
a number of :hand-held transGei~rer units of an
earli~r design are ~ alr~ady in the field
representing a substantial economic: investmerlt in
comparison to lthe cost of base ~tations,
2 0 accessories and components . I:n installations
spread over an extensive area, a larg~ number of
rnobil~ portable transcei~fer units may be employed
to gather data in various places and multiple base
tations ~ay be r~quired. ~ In a variety of su~h
25 ins~allations ~;uch ~ as warehouse facilitiPs,
di~trlbuti~n centers, ~ and retail establishments,
it m y be ~advantageou6 to utilize not only
;multiple basè capable of communic::ation with a
single `host, but with mul~iple~ hosts as well.
.
-- ~
SUBSTITUTE SHEET (RULE 26)
Wl~ 94/1077~ 2 1 4 8 3 ~ 1 PCr/US93/1052~ .
B~aRY O:F ~H~ INvBN~rIoN
~ he present invention provides an improved
data c:o~nunication system which maintain~ RF
communication links between one or more host
computers and one or ~ore base tran~cei~rer units,
each of which may b~ communicative with many
mobile portable transceiver units being moved
about a warehous~ complex for ~he collection of
data. Specific:ally, ~he inven~ion provides a data
communic:ation sy~;tem for collecting and
communicating da~a in the form o~ RF signals which
has a plurality of RF transceivers tha~ store and
modify at least one variable operating parameter.
From the stored parameter ( s ), each of
transceivers sontrol t~e operation of tran~;mission
and receptiorl. The transceivers also e~raluate the
ef f ect of the stored parameter based by analyz ing
eac:h transmi~;sion r~ceived, and determine whether
to make changes in the stored parameter. If
changes are needed? the transceivers, modify and
store the modif ied operatirlg parameter and begin
operation based thereon .
:rh~ operating parameters in~volve: l) the size
o~ data segments to be transmi~ted; 2 ) the length
or frequency of the spreading coàe used for
direct-~equencl~ spread spectrum commurlication; 3 )
the hopping rate, coding, and interleaving f or
frequerlcy-hopping spread spectrum communication;
and 4 ) the type of RF source encoding us~d .
3 û , In addition ~ the RF transcei~ers us d in' t~e
data communication n~twork s: f the present
invention use system-de~ault ~ralues to reset the
operating parame~ers if a serie~ of f ailed
c:ommunication exchanges occurs, so that
communication can be re-established.
It i~ therefore an object of the invention to
provide an adaptive radio communication system
which permits the intercormection of one or two
SUBSTITUTE SHEET (RULE 26~
wo g4/l0774 2 1 ~ ~ ~ 8 1 PCT~S~3/105~8
host computer devices to a multiplicity of base
transceiver units which may include both prior art
existing installed units and new generation units
capable of spread spectrum radio transmission.
}t is a ~urther object of the invention to
provide an adapti~e RF data communication system
which optimizes communication based on a set of
operating parameters.
It is a further ob~ect of the in~ention to
~O provide an adaptiYe RF data co~munication system
which maintains communication based on a ~et of
operating parameters ~or~optimazing communication,
wherein the operating parameters involve: l) the
siz~ of data ~agments to~be transmitted; 2) the
length or frequency of the spreading code used for
dire~t-sequence fipread pectrum communication; 3~
the hopping rate, ooding, and interleaYing ~or
- frequency-happing 6pread 6pect~um communication;
and 4) the type of RF source encoding to be ~lsed.
, 20 It is a ~urther object of the invention to
~i provide a radio communication Bystem network
. ~ contro}ler which via a communication exchange --
: optimizes a set of operating parameters, yet
returns the paramet~rs to t~eir ~previous or
system-de~ault ~alues upon failQd com~unicat~ion.
These and other objects of the invention will
. . be apparent from examination of the detailed
description which f~llows.
'D~CRIPTION OF~5~ DRA~IN~ FI~R~8 ! ~ i
: 30 Fi~ure 1 is a block diagram of the prior art
data communication system.
Figure 2 is a perspectiYe ~iew of the
inven~ion.~ ~
Figure 3 is a s~hematic representation of an
~ : : 35 exempIary radio communication ystem utilizing ~he
: : invention. ~:
:~ ~ SUBSTITUTE SHEET(RULE 26)
:
WO94/10774 ~ s~ P~T/US93/1O~Z8
2 1~'83`81 4
Figure ~ is a diagrammatic illustration of
the control circuitry elements of the invention.
Figure 5 i5 a rear elevation view of the
invention.
Figure 6 is a diagrammatic illustration of
the application spe~ific integrated circuit of the ;;
invention. ,`.
Figure 7 is a block diagram showing an
I ex~mplary implementation of intelligent network
and router transceiver units such as the network
tra~sceiver uni~s of Fisure 3.
Figure 8 is a diagram of an RF ~y~tem
utilizing a network controller according to
Figures 2-~, with nne of its network ports
confi~ured for commun~cation with a second host,
and another of its ports coupled with a
multiplicity of RF transceivers via an adapter
u~it~
Figure 9 is a diagram illu~trating the use of
two network controllers according to Figures 2-6,
configured for dual ho~t computers each, and
having their relatively high data rate extended
distance network port~ coupled with a multiplicity
o~ intelligent network and router transceiver :~
units implemented according to Figure 7.
~i~ure 10 is a diagram similar to Figure 9
but ~howing the paxi of coupled network ~:
controllers interfaced to a common relatively high --.
data rate sy~tem having multiple hosts le q.) a
~ 30 ~ocal ~area network o~ ~he E~hernet type or
; equivalent ~g~ fi~r optic type.
Figure ll is a diagram similar to Figure 10
but indicating the netwQrk controllers being
c~upled to re~pectlve diff~rent high data rate
multiple host sys~ems (e.q., token ring type local :.
area networ~s or other indi~idual networks e.g~,
fiber optic loop networks of thP collision-sense
multiple-access type)~- -
- SllBSTITlJTE SHEET (RULE 2S)
~V094/1~774 21~ PCr/U~93/11)528
Figure 12 is a viaw similar to Figure 9 but
intended to diagrammatically ir.dicate a
distribution of network and router transcei~ers
and oth~r elements c~f an on-line RF da~a
colll3ction system over an extensive area o~ a
f acility ~ of one o~ the type~; previc~usly
mentioned O
Figure 13 show~; an intelligent control ler and
radio base unit which unifi~s controller and radio
rompon~nts such as sho~n in Figure 7 illtO a single
housing of the size represented in Figures 2 and
5.
Figure 14 shows a diagrammatic illustration
of the signal proce~;sing for two of four paiis of
communication ports of~ the multiple bas~ adapter
of the RF da~a collection system illustrated in
Figure 8.
Figure 15 is a diagram of parts of an RF data
collection sys1:em utilizing a network c:ontroller
according to Figures 2-6 ~ and a multiple bas~
adapter according to Figure 14, with eight ba~;e
transceiver units coupled to the multiple base
adapter ~
~ .
D~TA~ED lD~ RIP~IO~ OF q!:E~E~I~V~NTION
Figur~ 1 shows an existing ~adio frequency
data tranqmission system 10 wherein a ~se sta~ion
t~ansceiver means îl has a number of mobile
transceiYer units suoh as 12A, 12B , . . ., 12N in
radio c~immunication therewith.
By~ way of example, the base station may be
compri~ed of a radio base unit 14 ~;uch as the
~: ~model RB3021 of Norand Corpoxation, ~Cedar Rapids,
Iowa, whic:h forms part of ~ a produet family know~
: as the RT3210 system. In this c:ase, the r~dio
base 14: may recei~e data from ~he respective
mobile;RF te:rminals, e.g. of ~ type RT3210, and
transmit the received data ~ via a network
SUBSTlTUTE SHEET (RULE 26)
: : ~: : :
W~ 94/10774 2, 1 48 ~3 8~ 1 P~r/V~93/1~5~8
.t ~
. 6
coIItroller and a communications link 16 ( e . g .
utilizing an RS-232 format) to a host computer 17.
The data capture terminals 12A , 12B , . . ., 12N
may each be provided with a keyboard such as 18,
a di E;play as at 19, and a bar code scanning
capability~
Figure 2 provides a perspectiv~ view of the
inventi~n 4 0 in the pref erred embodiment case 2 0 .
Front pan21 2 2 is provided with display 2 4 and
selec:t key ~, up key ~8 and down key 30. Power
indicator 32 comprises a low power green light
emittirlg diode which is energized wh2n power is
supplied to the invention lO. Error condition
indicator 34 is a yellow LED which is software
controlled to be ener~ized i~ the invention 10 is
in error coTI~ition.
Figure 3 discloses a diagrammati ::
illustratioll of a radio com~unication system in
: accordance with the pre~ent invention. Invention
2 0 networ}c controller 4 0 is coupled to host computer
4 2 ~uch that data may b~ interchanged batween the
. device~; ov~r host communications link 44, which
. may be either in ~ an RS232C forma~ or selectively
in an RS422 fo~at. The host communication link
44 couples to c:ontroll~r 40 a~ host port 46~
First co~munication port 48 of controll~r 40
provides ~ means fox coupling of ne~work S0 to
contxoller 40. Network 50 cc:mprises a mlmber of
ba~ RF ~ransceiver units 52A, 52B and 53B, ~ach
3 0 c~f which may be selsctively employed irl the radio
frequency communi~ation of data ~rom mo}: ile
trarlsceiver uni~s. It is to be understood that
base transceivar lmits 52 are dei,igned and
equipped to be operable in the exchange of data
with; network c:ontrGller 40 over network link 56
such that ~ach base transceiver unit 52A, 52B, or
53C may independerltly ~ixchange data with networX
conl:roller 40 through first communication port ~8.
W094/l0774 2 1 ~ 8 3 ~ 1 PCT/y~93/l0528
When first communication port 48 is int~nded for
operation with a network such as network 50 of
base transceiver units s2A, 52~ and 53C, for
example, network controller 40 is se1ective1y
operatod to pr~vide an RS485 inkerface at first
communication port;4~.: First c~mmunication port
48 ~ay be a1ternat~1y se1ected to opera~e as an
RS232C interface, as an RS422 interface, as a
proprietary NORAND~ Radio Qne N~de Network
int~rface or as a high speed V.35 interface. The
se1ection of interface to be provided at first
communication port 48 is front panel~ controlled,
that is, the user may oper~te front panel keys 28,
30 and 26 (See Fiyure ~2~to direct the proper
int~rface to be provi~ed at fir~t communication
:: port 48.
: Base transceiver units 52A, 52B, a~d 52C are
coup1ed to network link 56:by serial m~ans, rather
.
~: : than para1lel~ means, `and .ea~h may;be caused to
transmit or to recei~e:independentl-~ from the ~.
others:while~àdditionally~being communicative~with ~ - ~
. ~ ~ network controlIer 40::~in :a random1y chosen `:
~ fashion.
: ~ : : It;is ~urther~to be~understood that~in~erface ~ -
25~ translati~n is~provided with~in~;controller 40 fiuCh
~ that:data~communicated at first~co~munication por~
;~ : 48~may~be~ directed to:~host~42~;at port~46 via~
proper:1y chosen~interfac~ means~:as~is~r~quired~by ~ : : .'
: the host 4~2~with which communication is intended.
~1 ~`:Like first communication~port :`~8, ~second'` .
co unication~por~57;~may~be:;internally~6witched~
among~inter~ace~ choices~:~of ~h~se~ypes:. RS232C~,
.35~ Rs4~g5~an~propri~e~ary NORAND~ Badio~
One~ Node~ Nètwork~interfaae.~ In the :i11ustrated~
35~ ;arrang~men~ ;of~:Fi~gure~ 3~ o~ ~example, ~second~
communication~:port~57~ is ~coupled over thi~d 1ink
53 to previously~lnstalled base transceiver 54,
S~ which heretofore~had~been used:in a prior art~
WO 94/~0774 ~ ; 2;1 4`8 3 8 1 P~rtU~S93/105~8
system as is illustrated in Figure l. Because of
:Limitations of base trarlsceiver 54, it must
communicate Yia RS232C interface format and
therefor~3, second communication port 57 mus~ be
5 se1 ~cted to operate in RS232C interface mode .
However, when second communication port 57 is
desired to communicate with a network ~ria RS485
interface, front pan~l keys 26, 28 and 30 may be
manipuiat~d by the user tct pro~ride the RS4 8 5
lû int2rface availability at sec:ond communication
poxt 570 IJikewise, second coI~ununicativn port 57
may be selected to operate as an RS4 2 2 interf ace,
as a V.25 interface, or as the propriet ry NO~AND~ :
Radio One Node Network interf ace .
Diagno~tic port ~ 55 provid~s a f ourth
cc~mmunicatioIl pathway f or network ::ontroller 4 0,
providing an async:hronous port operable at 3 o0 to
19, 200 baud as an RS232C interface . When
d~sirable, diagnostic port 55 may be couplsd by
diagnostic lin)c 58 to diagnostic device 60 for
purposes of error diagnosis of corltroller 40 by
diagnostic device 60, or for reprogramming of
memory devices within controller 40 when desired.
It is co~templated that diagnos1:ic device ~0
comprises a 16 or 32 bit microproce~sor commonly
known as a personal computer or "PC". ~he mode of
coupling between diagnostic: device 60 and network
controller 4 0 may be direc~ or through remote
means by use of a modem~ :
i j ~ R~ferring now to Figure 4, a~ cer~tral
proc:e~ing unit 70 is pro~rided wilth at least four
data communication ports, illustrated at num~rals
71t 72, 73, and 74. First data cs:mmuilic:a ion port
71 may be selectively coupled to RS232 interIa ::e
membar 76 or~VO35 interface msmber 780 The choice
of whether :E~S232 interface member 76 or V. 35
interf~cQ member 78 is chosen i~ dependent upon
the opera~ing characteristics presented by the
.
T} ''T~ T (~ r;~
WO94~10774 '21 ~ 83 PCTtlVS93/10~28
9 ..
host computer, such a~ host ~omputer 4Z of Figure
3, with which network controller 40 will
communicate, The choice of whether first ~;
commUnication port 71 is coupled ~o interface
member 76 or ~o interface member 78 depends on the
front panel s~lection made by the user by keys 26,
28~ and 30 shown in Figure 2. :
Second communication port 72 may be
selectively coupled to RS232 membPr 80 or to RS485
I 10 interPace memb~r 8~ or to RS422 interface member
j . 84 or to NOR~ND~ Radio One Node N~twork .;
I proprietary interface member 86. By use of front
panel keys 2~, 28, and 30 o~ Figure 2, the user
may select ~econ~ communica~ion port 72 'to be .
1~5 coupled to any one of~interface me~b~rs 80, 82,
84/ and 86.
: Third communication~ port 73 is ide~tical to
~ ~ second~ communica~ion port 72 in functionality,
: : ~ being ~electively couplable to RS232 interface
~ 20 member 8~, to RS485 in~erface member ~0, to~RS422 .`
: ~ inter~ace member ~2::or to:NORAND~ Radio One Node ~ -
; ~ Network proprietary interface member ~4. -~
: : ,~ In~the~pre~erred~embodiment of the inventiOn
:~ ~ 40, central proces irlg unit ~70 of ~Figure ~ 4
:Z5 ~comprises; d~ Motorolan'~ ~68302 ~ integrated chip
: cooperative with I an: application ~ æpècific
integrated ~circuit. ~entral prace~sin~ ~unit 7 0
employs novel features allowing-the bidirectiona~ ~ :
~ ~ use of ~~a data co~municative ~line~of the ~o~orola~:~ ~ 3 0 '68302 c:hip and a singlei clock: signal line to `~
~ ~ ~ eliminate~the need ~or coder-decoder~members to be
: ~ associated w~ th~ ~ the ~ N~torola~ : 683 Q2 : chip:~; while:
::~ ~ : allowing the~use oiE only c: ne pair of signal wir:~s
to be::;coup~led to~:the RS4~8S ~interfaces 82 and 90~ of
3 5 ~ Fi~ure ~4
Fourth ~ communication port 74 of ~: central : ;~
processing unit is coupled to a~ynchronou~: RS23
SUBSTI~UrE SI~E~T (RULE 263 ~ :
~ir ~ ~r .\~
W094/10774 ~ 1~ 8 3 8 1 PCT/US93/105~8
, 10
inter~ace member 97 to be avallable for
interconnection of a diagnostic device therewith.
Also coupled to central processing unit 70
are display member 24 and keyboard member 31 with
which keys 26, 28, and 30 of front panel 22
(Figure 2) are interactiv~
Memory alements including EPRO~ element 96,
DRAM u~it 98, FLASH memory unit 100 and EEPROM
element ~02 are intercoupled with each other and
with central processing unit 7a.
Power supply member 104 is selecti~ely
attachable to invention network controller ~0. In
order to avQid the necessity of different models
. of network controller 40 depending on the local
electr~cal power ~ utility's operating
characteristics, power ~upply 104 is provided in
optional model~ depending on the country in which
.i it is to be used, power supply 104 being eapable
of providing ~atisfactory output power to network
controller 40 regardless of the ~oltage or
frequency of thP input source provided to power
; I s~pply 104. ~:
The application speci~ic integrated circui. :~
tASIC) us~d in the inventio~ n~twork controller 40
is disclo~ed in Fi ~re 6 and is identified by ~he
num~ral: 12C. ~SIC 120 comprise~ a central
. processor unit interface 122 member which is
coupled to the central processor unit bus by CPU
bus link 124 which extends from ASIC 120, Also
' 30 coupled to t~e CPU bus link 124 is dynamic ~andom
acc~ss memory (~RAMj timing element 126, which
provides network controller 40 with timin~ signals
for the DRAM member 98 illustrated in Fiqure 4
when m~mory refresh of the DRAM ~8 is indicated.
DRAM timing elemen~ 126 is also coupled exteriorly
to khe ASIC 120 to DRAM member 98 by DR~M link
127.
:
.,
,
~ t~f~ t ~
W~4/10774 2 1 ~ 8 3 8;~ PCT/US93/1~528
._.~) .
11 .
Central proc~ssing unit interface 122 is
coupled to a~ynchronous signal processing ~lement
128 by signal path 130. ~s~nchronous signal
prvce~sing element 128 co~prisas a ~aud rate ~.
generator cooperative with a univer~al
as~nchronous receiver-transmitter.
Also coupled to central processing unit .-
inter~ace 122 i~ network clock and control member :~
132 w~ich compris~s a~programmable net~ork clock
gen~rator which can be selectively programmed to
generat~ an op~ional clock speed:for~a network to
be coupled through RS485 interfaces ~2 and 90 seen :~
in Figure 4. Network clock~and contxol member 132
; also provides detection ~eans for detections of
failure conditions ~n a~ linked network! and
provides control signals to system components in
respo~se thereto, including interrupt signal~ to
programmable interrupt coordinator circuitry
included in~ ~entral prooess$ng interface 122.
Network clocX and controller member 132 provides
data encoding by the F~O standard, then the
: : encoded data may ~e opera~ed upon by RS485
; interfa~es 82 and 84 and transmitted and received :
by single twisted pair means o multiple serially
networked: bass tra~sceiver units exemplified ~y
~:: 1 : ;base ;~ transceiver unit ~52A, 52B, and 52C~
~ :illustrated in~Figure 3. ~ ~ è
:~ . ~ : Keyboard con~roller element 134 is coupled to
central:processing uni~ interface and provides a:
3 0 ~ink exterior to ASI~ 120 to~eyboard 31 (See
Figure~3~
FLASH m2mory/EEPRO~ logio control member 136 :
is coupled~to cen~ral processing uni~ in~erface
: 122 and ~comprises~dontrol functions for FLASH
35 ~ memory elem~nt lO0 and EEPROM memory element 102
of Figur~ 3.~
,
:
7 g~ T' 5 ~
W094/10774 2 1 ~ 8 3 8 1 PCT/US93/10528
12
Central processing unit interface 1~2 is also
coupled by line 13~ to latches exterior to ASIC
120.
It is to be understood that the base
:l 5 transcei~er units 52A, 52B, and 5~C illustrated in
Figure 3 are communicative with mobile transceiver
units by ~lectromagnetic radio mea~s. The mobile
transceiver units may be associated with bar code
scanning devic~ such as the: NORAND~ 20/20 High
Performance Bar ode Reader whereby the scanning
device~ ~can an object having a bar codP
associated therewith and collect information
stored in the bar code, which information is then
. transmitted through the mobile tran~ceiver units
. 15 to base transceiver uni~s such as base transc~iver
units 52A, 52B, and 52C or base tran~ceiver unit
54 of Figure 3. Th~ bar code data received by
- said base transc2iver units i6 then transmitted in
the example of Figure 3~ o~er network 5~ by base
transceiver units 52A, 52B, or 52C, or over link
53 by base transceiver unit 54, to network
. contro~ler 40 which performs the routing and
:`, delivery: of the data ~to the ~tationary data
: processor, or processors, such as shown for
example, by host ~2 of Figure 3~ ;
~: De~L~hrouah 11
Figure 7 ~hows : a block diagram of ~.
particularly pr~ferred intelligent base
transceiver unit known as ~he ~B4000. It will be
observ~d that the oomponents ~orrespond with
components o~ the:n~twork controll~r of Fiyure 4,
:
and~similar reference numerals (preceded by 7-)
:: have: been~ applied in Fi~re 7 . Thus, the
:; significanc~ of components 7-70 through 7~73, 7-
:
: ~ : : :: .
- :
5 3BSTITUTE S~IEET (R~LF ~)
W094/10774 21 ~8~8f pCT/US93/10528
13
76, 7-82, 7-9~, 7-98, 7-100 and 7-104 will be
apparent from the preceding de~cription with
respect to Figure 4 and 6, for example. I/O bus
700 may be c~upl~d with a spread spectrum
S transmission (S5T) or ultra high frequency (UHF)
transceiver 701 which may correspond with any of
the transcei~ers of units 52~, 52B, 52C or 54
previously referred to. The network controller 70
~ould have a similar RF transcei~er coupled with
its data port 72 or 73 and controlled via
input/output bus 400, e g. for direc~ RF ~oupling
with router transceiver6 such as 901, 901, Figure
. 9^ ....
Referring to Figure 8, a network controller
40 is shown with:port 71 configured ~or interfac~
: wlth a ho6t port typ~ SNA ~. 35 5~K/64K bits per ,'r,:'
. second. Port 72 is shown as con~igured for
. communic~tion with a personal compu~er of the P5/2
type operating asynchronously at 38.~R bits per
; 20 second, Port 74 is co~p~ed with a mod~m 8-~0
: providing for r~mote diagnostics and reprogramming
of the network controller 40.
Port 73 of network controller 40 is shown as
being connected with: an adapter component 801
.~` 25 kno~ as Norand Corporation MBA30000 In the
: operating mode i~dicated in ~igure 8, the adapter
801 serves to couple ontroller 40 5equentlally
with four radio base tran~ceiver units uch as
indieated at 811 through 814. Compone.~t 811 is a
:
SUBSTITIJT~ SitEET (RUL~ 26)
'
I W09~10774 ; 2 1 4 ~ ~ 8 1 P~T/yS93/10528
14
I commercially a~ailable radio base known as the
RB3021 of Norand Corporation. Base station 811
may co~municate with a multiplicity of hand-held
RF data te~minals such as indicated at 821. Base
814 is indicated as being coupled with the adaptor
80~ via RF broadband modems 831 and ~3~ Base
units 813 ahd 814 may communicate with mobile
transaeiver units such as those indicated at 833
.and 834.
Figure 9 ~hows two network controllers 40A
and 4OB each with i~s host ports configured as
with the controller 40 of ~Figure 8. In this
: ~ example~ the second ports 72 of the controllers
. 40A and 40B are confi~ured for communic~tion a
relativ~ly high data rate rel~tively along a
distance netvork channel 56 which may have the
j characteri~tics o~ the serial channel 56 of Figure
.. 3, for example, an RS485 channel operating at 384
kilobits ~er second (334K bps). Network base
: ~ ; 20 transceivers 52A, 52B:and 52C may correspond with
the~correspo~ndingly n ~ ered transiceiver~units of
Figure 3, for example, and`the network may have
, ~ a~ditional network~transceivers such ag 52D.
Furthermore, the network~transceivers may have~RF
coupling with router~transceiver uni~s such as
indicated at 901, 902 and:903. Router transceiver
; unit 302 is:illustrated as a RB4000 intelligent
transceiver such as represented in Figure 7 ~nd
SUBSTITUT~ SHEET (R~LE 26)
~ .
~ ; ~
21 ~S381 :
WO9~/1077~ P~TJUS93J10528 .
~:
having its input/output bus 700 coupled with a
peripheral~ ;:
Figure 10 is entirely similar to Figure 9,
for example, except that ports 72 of the
controllers 40A and 40B are coupled with separat
serYal type high data rate network channels, and .~.
ports 73 of theirespectiveinetwork controllers are `~
coupled to a very high ipeed network e.~. in the
several megabi~s per second range such ~s an
Ethernet local area nekwork 1000. Suitable
interfaces are indicat~d at 1001 and 1002.
Figure 11 i& entirely~similar to Figure 9 ~^
except :tha~ the ports 73 of the network ~`
. controllers ~ 40A and 40B ~are eoupled with
respective local ar~a ring:type networks which may .-
be separate fro~each other and each have two or
. more ho&ts such as ~repre~ented in Fi~re 9
associated with the~respective ring networks &uch
as token rings llOOA and 1100B. Suitable
interface means are~indicated~at 1101 and 1102.
Descr~E~ion of Fi~re 12
Flgure~12 shows, for example, two network
: controllers 40A~and 40B, each with two host
; computer units such as 42 lA. Host 42-2A i shown
with~a printer or~ other perîpheral P1 ~hich may .'
generate bar code&:, for exampley for replacement
~ of damaged bar codes or the liki. Another printer
;~ P2 i& &hown a& ociated with base 52C, again for
SUBSTITUTE SHEET (R~LE 26~ -
WO94/10774 2 1 4 8 3 8 1 PCT/VS93/10528
16
example, for producing bar code labels where those
are needed in the vicinity of a ba~e stationO In
a large warehouso, relatively large distances may
be involved for a worker to return to a printer
such as Pl ~o o~tain a new bar ~ode label. Thus,
it may~e very advan~ageous to provide a printer
P2 at the base stati~n 52C which may be relatively
close to a processing location which requires
printed labels, e ~. a:processing location in the
~icinity of hand~held terminal 12-2 in Figure 12.
A base S2F may have a peripheral P3 assoc;iated
therewith such as a l~rge screen display, a
printer or the like which may supplemen~ the .
: capabilities of a hand-held terminal, for example
printing out new bar code labels at a convenient :~
location, or providing:a full scxeen display,
rather ~han the more limited screen display area
of the hand-held terminal ~12-2r -
: If, for example, a base radio 52D which might
~ b located at the ~eiling level of a warehouse
; became inoperative at a time when qualified repair
p2rsonnel~were not i~ ediately available, with the
pres~nt~system it would be feasible to provlde a
: substitute base radio or base radiost f~r exa~ple,; 25 as indicated at 5~Dl l~cated at ta~le level or the
.: . : ~ ~
like.
: : With~: the present system, the base radio
: stations ~ do not necessarily forward data
co~munications received from a ~iven terminal to
~:; :
~: - SUBSTITUTE SHEET (RULE 26)
WO~/l0774 2 1 ~ ~ 3 8 1 PcT/us93~los28
17
a particular host. For example, hand-held
terminal 12-2 may request a path to printer P~,
and such a path may be created via base ~tations
52Dl and 52C. Station 52C upon receipt o~ the
me~sage form terminal 1~ 2 would not transmit the
message to a hos~ but would, for example, produce
the desired bar code label by means of printer P2.
Furthar, terminal 12-2 may have provi~ion for
digitizing a voice message which might, for
example, be addressed to terminal 12-1. The
sy~tem as illustrated would be operable to
automatica11y establish a suitabl~ path for
example, ~ia stations 52D1, 52C, 52B, 52E and 1~-1
for the transmis~ion of this voice message in
digita} form. 5uccessive ~egments of such a voice
message would be ~tored~ ~or example, by the
terminal 12-l, and when the complete message was
assAmbled, the ~gmen~s would be synthesized into
~ continuouæ voice mes~age for the user of
termin~ 1 ~ by m2ans of a speaker 1201
also useful ~or send~ng tone signals indicating
valid bar code read, etc.
In accordance with the~present in~ention, a
hardware system such a~ illustrated in Figure 12
may be physically laid out and ~hen upon ~uitable
command to one of the network controllers ~uch as
42~2B, the entixe system would be progressively
automatically sel~-confi ~ red for efficient
operation. For example, controller 4OB could
- SUBSTITllTE SHEET (RULE 26)
W~94/1~774 ~1 4 8 3 8 1 PCT/US93/10528
18
successively try its communications options with
it~ output ports such as 71-73, determining for
example, that host processors were coupled with
ports 71 and 72, one operating on a 38.4 kilobit
per second asynchronous basis and the other
pr~senting a SNA port for the V.35 protocol at 64
kilobits per:se~ondO For example, on host, 42-lB
might be a main ~rame computer, while the other
host 42-2B migh~ be a PS/2 type computer system.
The controller 40B having thus automatically
configured itself ~o as to:be compatible with the
devices connected to ports 71 and 72~ could
proceed to transmit via~port 73 a su1table in~uiry
message to the network cha~nel 56. Althouyh a
~polli~g protocol is preferred, each of the base
stations could operatej for example, on a carrier-
~ ~ ~ sense multiple-access !CSMA) basis or using a busy
: tone protocol to respond to the in~uiry message
from the controller ~OB, until each of the
; 20 successive bases on the network had responded and
identi~ied~itself. Each base, for example, would
have a respective unigue address identification
which it could transmit in response to the inquiry
:
~:~ message :50 as to es~ablish its presence on~ the :~
network.
The controller~40B could then tran~mit auto
configure commands to the successiYe bases in
turn, instructing the bases to det~rmine what :~
: peripherals and router bases such as 52D1, 52E and
SUBSTITUTE SHEET (RULE 26)
WO 94/~0774 . 21 ~ ~ 3 8 I PCr/U93/10528
19 ~:
52F were within the range o~ such base~ and to
report back to the controller. For example, bases
such as 52C and 52F could determine the nature of
peripherals P2 and P3 associated therewith so as
5 to be able to re~:pond to an inquiry f orm a
terminal such as 12-2 ts:~ advise the terminal that
a b~ar ccde printer, for example, was within direct
RF range.
In the case of a breakdown of a component of
10 the system such a~ 52D, it would merely be
necessary to place a router device such as 52Dl at
a convenient location and acti~rate ~he unit,
wh~reupon the unit could send out its own
bxoadcast inquiry which, for example, could be
15 answered by the base ~;tations 52C and 52F, station
52C in turn, advising a relevant host or hosts of
the ac:tivation of a substitute router station.
Thus, lthe sys~em is corlveni~ntly re-self-
configured without the nece~sity for a technician
20 familiar with the particular configuration
procedure. As another example, where the base
stations are operating utilizing spread spec:trum
transmission, the introduction of barriers ( s~ach
as a ~ new stack of inventory goods) to suc:h
25 transmis~io3l between a given base such as 52A and
various terminals, could result in the base 52A
contac:ting roulter 52E, for example~ with a requ~st
to become active with respect to the blocked
terminals. ~:
r~ T t~in;i ' , ~;~~3,~
WO94/1077~ 2 1 4 8 3 8 1 pi~T/ys93/lo528
Description of Fi~ure 13
Figure 13 shows an intelligent integrated
controller and radio base unit 1300 which is
integrated into a single housing or case 1301
corresponding to the case or housing 20 of Figure
2. the housing 1301 may be pr~vided with an
external antenna as diagrammatically indicated at
1302 with suitable RF: coupling to the radio
circuitry indioated at 1303. Components 13-70
through 13-74, 13-76, }3-78, 13-96, 13-97, 13-98,
13-100, and 13-1~2 may oorrespond withi the
: correspondingly numbered components described with
; reference to Figure 4.
::
SUPPLEMENTARY DISCUSSION
In accordance with the present disclosure, a
network contro1ler, ~ or : integrated network
contro1ler and radio~ unit`is;coupled to one or
more host computers via`~ standard interface such
as commonly encountered in practice (e.q. ~S232,
. .
; 20 V. 35, Ethernet, ~oken ring, FDDI,:and so on). In
this way, no specialized intérface or adapter is
re'quired for the host.
` Since the preferred network cantri~ller can
connect to two hosts,: if one h~st i~ detected to
have failed, or in the event of a system crash,
loss of commùnication link, or the like, the
: network contrQller can automatically switch to the
: : . ~
second~host. ~ The second host may be a truly~
SUBSTITUTE SHEET (RULE 26)
:
..
W094/10774 21~33 Pcr/us93/
redundant syste~r or may bP a simpler computer of
the PC type (a so~called personal computer) that
can 8imply store transactions until the main host
is restored~ As ~nother example, a single host
may ha~e a second port coupled to a second port of
the controller especially if a CnmmunicatiQn link
failure may be a problem. For examp}e, two ports
of the network controller may be coupled ~y
separate modems with separate phone lines, leading
to separate ports of a sing~e mainframe computer,
for example an IBM3090. In a fully redundant
system, two ports of a network controller may be
connected respectively to two mainframe computers
such as th~ IBM3090.
The disclosed network controller can al50
connect one radio network to two hosts using RS232
or V.35 ports vr to many host~ using a local area
network uch as Ethernet, token ring, or FDDI. A
number of the disclosed network controllers (for
example, up to thirty-two) can be connected
kogether to interface many hosts to a single radio
network~ The hand~held portable terminals in such
a network can then talk to`any of the hosts they
choose.
For example where Qn~ port of the disclosed
: network controller is coupled via its ~S232
interface to a mainframe computer such as the
IBM3090, another of its ports may be coupled via
: an FDDI network with a super computer ~ ~ the
u-r~ r~
WO94/10774 2 1 ~;8 3 8 1 PCT/US93/1052~
22
Cray X-MP. Then mobile and/or portable terminals
can access eithe~ the main frame or the super
computçr J or in general, ~ny of the hosts that are
connected to the networX controller.
As indicated in Figure 9, four hosts can be
on one network. Referring to Figures 10 and 11,
a multiplicity of hosts may be coupled with each
local area network so as to be in co~munication
with one or more of the disclosed network
controllers. Furthe~more, a single disclosed
network contr~ller can control two radio networks
such as the one indicated at 50 in Figure 3.
Where each network such as 50 is limited to
thirty-two devices, the number of devices is
: 15 doubled with the use of two radio networks. Two
: such radio networks may also be utilized for the
~ sake o~ r~dundancy, with a provision for automatic
switch-over from one radio network to the second
if a~pro~lem develops on thP first. ~wo radio
, .
~0 networks may also facilitate the use of different
~: radio technologies in-one ins~allation.
~.
The various multi-drop local area networks
referrèd to herein, for example at 7-82 in Figure
~; 7 and as ~represented at 56, 56~, 56B, Figures 9
through 12, and at:13~ in Figure 13 may comprise
HDL~ based local area networks operating at up to
:~
2.S megabits ~ per secon~ and using biphase space
ancoding (F~O3 for clock recovery from data.
.
-
:::: : :
SUF~`~3Ti~r- S~ T ~ULE ~v)
W~94/10774 ~ PCT/US93/10528
23
The component~ 86 and 94, Figure 4, and
component 13~ igure 13, provides a low-cos~
base radio interface using three pairs of twisted
conductors. One pair provides a bidirectional
RS485 data line. Another pair is used for the
clock and has an RS422 electrical configuration,
and is one directional~from ~he radio to the
controller. The third twisted pair is also RS422
and is used to communicate from thP controller to
the radio transceiver to effect mode selection.
An aspect of the invention resides in the
provision of a network controller having port
means selectively configurable for couplin~ in
first mode with network RF transcei~er units at a
relatively high data rate such as l00 kilobits per
second or higher, and for coupling in a second
mode with network transceiver units at a
-.,
relatively low :data rat~ such as ab~ut twenty
kilobits per second. Preferably a single port -:
means such as 2, 3, or 5, 6, Figure 5, can be
so~tware configured to inter ace selectively in
the first mode or in the second mode. It is
preisently ~less expensive to ` use mult~ple .,
: connectors per port rathe~ than a single 37~pin :~
.
connector~for exampIe.
Where: :a network controller such as 40
operates two bigh data rate netw~rks, for examp~e,
one network of RF base transceivers could operate
with the RTC protocoI, and the second network
SllBS~ITlJTE SHEET ~RULE 26)
W094/~0774 Z~ 81 PCT/US93/105 8
24
co~ld operate according to a different protocol.
It will be apparent that many modifications and
variati~ns may be effected without departing from
the scope of t~e teachings and concept of the
present disclosure.
De~criptiQn of_Fiqures 14 and 15
: ~ Figure 14 is a block diagram of the circuitry
for one pair of ~ommunication:ports 1401 and 1403
o~ adapter ~01:(fig.:8) for use in coupling to base
transceiver u~its. Three additional pairs of
communication parts for c~upling to six additional
base transceiver~ un~its are provided in the
mbodim~nt of adapter 801 a~ :exemplified by the
Norand Corporation MBA3000 Multiple Base Adapter.
: : : ~
: 15 It is to be understood that ~he:circuit components
~ coupled to each additional pair o~ communication
. ~ ~
ports of~adapter 801 is ~identical to that shown .`
for first port pair lA/:lA,;that is ports 1401 and
1403 of Figure;14.: The adapter 801 provides means
~Por connecting the controller 40 (Fig. 8)` at its:~
port 73 to a multiplicity of radio base uni~s
: illus~rated in Fig.~8~as, for~example, 811, 812,`
813,~ 814,~ including;in selected pairsO~ In the
preferred~embodiment:o~adapter ~01, up to eight :
radi~ ba6e~ unit6 may~be coupled ~hrou~h use of
; adapter ~801~ to~a;n2twork controller 40, to be
: controlled ~by controller 40 in seIected pair~
the~eof. The contraller 40 may control the radio
SUBSTlTUTE SHFET (RULE`~)
W094/l0774 ~ ~ PCr/US93/10528
base units such as 811, 812, 813, 81~, (Fig. 8) in
simulcast mode, that is, with all base radios
interrogating mobile transceiver units such as
821, 833, and 834 of Fig. 3 simultaneously, or
with the base units being employed in pairs to
interrogate the mobile transceiver units.
¦ Referring again to Figure 14, the network
controller 40 pro~ides transmit data and baud rate
select sig~als to adapter 801. Within adapter
801, the controller outputs are converted to TTL
levels by TTL converter 14~2 and they are then
provi~ed to buffer 1404 which provides the signals
to paired RS232 transceivers 1406 and 1408, and to
paired RS422 transceivers 1410 and 1412 which
deliver the conver~ed ~ignals to ports 1401 and
1403 respe~tively. By this means, the ..
controll~r'~ DUtpUt signals are provided to a pair
of output ports 1401 and 1403 in both RS232 and
RS422 in~erface at the same time. An additional
three output-port-pairs are provided which may be
denominated 2A/2B, 3A/3B and 4A/4B, which ports
are controlled and operated identically to ports
lAllB identified in Fig. 14 as ports 1401 and
1402. The ~5232 transceivers 1406 and 1408 and
, ~ 25 RS422 transceivers l410 and 1412 and ports 1401
I and 1403 are illustrati~e of all circuitry coupledi to port pairs of adapter 801.
Similarly, signals provided to adapter 801 by
b~se radios coupled to the output port pairs,
W094/10774 ~ 8 3 8 1 PCT/~S93/lQ~2g
26
ports 1401 and 1403 of Fig. 14, are first
cs:~nverted to TTL levels by the RS232 transceivers
1406 and 1408 or by the RS422 transceivers 1410
and 1412, depending upon which interface is
presented by a pair of base radlos at port 1401 ;~
and 1403. The signals provided to adapter 80~ are
then forwarded by the transceivers 1406 and 1408
or 1410 and l412 at TT~ levels to controller 40t
A selection unit 1414 provides a push-to-talk
selec~ion signal to the RS232 t~ansceivers 1406
and 1408 and to the RS422 transceivers 141q and
. . .i .
1412 to provide PTT select-ion signals at ports
1401 and 1403 in both R523~ and RS422 format. It
is to be und~erstood that similar selection units
1S ~ are ~associaCod with remaining port~ pairs 2Aj2B,
3A/3B~ 4~/4B so that the ports may be
independently~operated.
The àdapter~ 801~of Fig.8 is exemplified by
the NBA3000~ mu~ltiple~ base adapter ~ unit
20~ manufactured~by~the NORAND~Corporation of~Cedar
Rapids,~;Iowa. ~Because of the operation of the
MBA3000 multiple base adapter by dual method~ in
; eith~r R5232 or RS422 signal énvironments, the
MBA3000~ may~be incorporated~into 6ystems having
25 ~ exi~ting~in~tà~lled base radios whlch present only
an~R5232~interface or~it may~be incorporated into
systems~having base~radios some~of which operate
at RS~22~and some at RS232.
5~^3TlT'JTE9'~ R'JLE7~
W094/l077~ 2~33 PCT/US93/105~8
Fig. 15 illustrates a preferred arrangement
of controller 40 and adapter 801 when used in an
environment with multiple base radios in multiple
warehouse environments~ Controller 40 is coupled
to adapter 801 which is coupled to paired bases
1511, 1512; 1513, 1514; 1515, 1516; and 1517,
1518, which are located in warehouses 1501, 1502,
1503 and 1504~ By geographical separation in
warehouse l501, for example, base radios 1511 and
1513 provide subskantial coverage of warehouse
1501 such tha~ a mobile transceiver beiny iused
~ithin warehouse 1501 would be communicate~ with
b~ either base radio 1511 or 1513, By the u5e of
adapter 801, controller 40 may cause interrogation
simultaneously by base radios 1511, 1512, 1513,
1514, 1515, 1516, 1517, 1718, or it may cause
.
sequential interrogation by radio pairs lSll/1512,
1513/15l4, 1515/1516, or 1517/1518 in successionO
When a mobil~ transceiver re~pon~s by RF
communication means with a base radio, e.q. base
radio 1511, the response is transmitted by base
radio 1511 through coupling lS21 to adapter ~01
whlch automatically converts the incoming response
to RS232 interface as necessary, to make it
2S suita~le for reception by controller 40.
Through a system as exemplified in Fig.15,
: data collection from a number of roving mobile
transceivers may be initiated by a ne~work
controller 40 through a ~our warehouse
,
T~ ~H~ J~
WO94/10774 ~ 4 8 3 ~ 1 P~T/VS93/10528
28
environm~nt. When base transceiver units 1511 and
1512 have been unsuccessful in establishing
communication with the desired mobile transceiver
¦ unit, controller 40 will then cause bases 1513 and
¦ 5 1514 to attempk communication and if bases 1513
and 1514 are unsuccessful, controller 40 will
proceed ~hrough the other base radio pairs, namely
1515/1516 and 1517/1518, as needed, to es~ablish
communi~ation with the desired mobile transceiver
`:
.lO unit. ~ ~
The adapter 801 is:provided to operate in
~ : either slmulcast or sequential moda. In ~he
! : ~ normal or simulcast mod~, adapter 801 allows the
use of one to cight bases,~where the bases are
configured as four pairs of two ba~es. In this
mode the~adapter 801 simulcasts to a ingle ba~e
: : pair at a time and the four sets:of base pairs are
selected~ using¦ a dynamio time-dlvision
multip~lexing method. The user:::can configure the
20~ : adapter 801:to use any :o~ the eight base ports,
usin~g simulcasting or time-division multiplexing
to~best advantage.
Thère are two sets of base transceiver units,
referred~ to as set~A (identifled as lA, 2A, 3A,
25~ ~and~4A):and ;set B (:identified as lB, 2B, 3B, and
4B~. With~in~a~set, the base transceiver units are
` selected~byltime-division multiplexing. ~
It can be se~en in Fig. l5,~ that there are
four pairs~ of base~transceiver units de~ir.ed-as
:: : :. : : : .
3 U ~-- S~ iL ~;)
W094/10774 ~ ~ ~ PCT/~593/10528
29
pairs lA/lB, 2A/2B, 3A/3B, 4A/4B. Each base
transceiver unit of a base pair is simulcasted to
at the same time.
The hardw~re of the adapter 801 allows the
~election of the base pairs ~pair 1~/lB through
4A/4B) using control lines from the controller 40.
Adapter 801 transmits to both base transceiver
units of a base pair at the same time and receives
independently from each base simultaneously.
10The use of adapter 80~ allows an extension of
the number of ~ase transceiver units that oan be
used in a~facility to allow for adequate coveraye,
i~ is important to understand how the base
transceiver units operate when simulcasting is
¦ 15used, and when time-division multiplexing is ~lsed.
: The adapker 801 distributes signals
:transmitted by controller 40 to base transceiver
pairs at the same time,~so if there is an overlap
in the coverage for the two base transceiver
u~its, there may be some interference. The a~ount
: of interference depends on the relative signal
strengths; if the strength is similar in one spot
the chance o~f interference is larger that if the
signal~ strengths are di~ferent. This type of
interference could be avoided in some
con~iguration~ by splitting coverage areas of
~: ~ pairs of base transceiver units. Another ~ethod
of covering:the overlap area is to place another
: : base (not one of the base pairs) to cover the
SuByl~U7~E S~EFT (RULE 26~
WO94/10774'~ 8 381 PCT/US93/10528~
overlap area. The radi~ signals from ~he mobile :
transceiver unit may be picked up fully or
: partially by either or both base transceiver units
of a given pair. However the adapter 801 first
5tries to receive from one base transceiver unit,
~or example base 1511, and if unsuccessful, it
then~switches to~try to receive from a second base
transceivex unit, for exàmple base transceiver
. unit 1513. If the~information is successfully
10received from the~first base transceiver unit, the
infarmation from the second base transceiver unit
is ignored. Thus the~controller assures data does
~ ~ ~ not get s nt to the~ ho~t data processor in
: ~: duplicate.
15 ~:The ~ user may:couple~from one to eight base
.~ ; ;transceiver:~units to the adapter 8~01:and can then
: ` ~
:~ ~ ~ configure those base transceiver;units as required
;~ to meet the installation's needs.~ Any~combination
; : : of ports of the adap~er~801 can be used. Thus the
~ :20 user~ can take advantage of ~the ability ~to
:~ ~ :simulcast~r sequentially ~via time-division ~:
: ~ ~
multiplexing) access~:the base transceiver units
15ll, 1512, ~1513,~ 1514, 1515, 1516~ 1517, and
: :~ : : :: : : :
2~5 Multipath adlnq and::D
In a~ referred~embodiment, the data (or
~ messages~ to~be sent;~through~the RF communication
; ~ : link is~se~mented into a plurality of DATA packets
;~ SUBSTITU~E SHEET (RULE 26)
`
WO94/10774 ~d,g~ PCT/U593/105~8
and is then transmi~ted. Upon receipt, the DATA
packets are reassembled for use or storage. Data
se~mentation on ~he RF link provides better
communication channel efficiency by reducing the
amount of data loss in the network. For example,
because collisions between transmissions on an RF
link cannot be comp~etely avoidPd, sending the
data in small segments resuIts in an overall
,
decrea~e in data loss in ~he network, i.e., only
the small segments which collide have to be re-
sent.
Similarly, choosing smaller data packets for
transmission also reduces the amount of data loss
by reducing the inherent effects of perturba~ions
and fluctuations found in R~ communication links.
In particular, RF signals are inherently subject
to what is termed '~multi-path fading". A signal
! received by a receiver is a composite of all
~ .
signal~ that hav~ reached that receiver by takin~
all available paths~from the transmitter. The
~; receiYed signal is therefore often ref:erred to as
a "composite signal" which has a power envelope
equal to the vector sum of the individual
components of the multi:-path signals received. If ~-
;~ 25 the:signals making up the composite signal are of
:
:~ amplitudes that add "out of p~ase", the desired
.
~`~- data signal decreases in amplitude. If the signal
amplitudes are approximately equal, an effective
W094/10774 2 ~ 4~3 ~ 1 PCT/US93/10528
null (no detectable signal at the receiver) ;.
results. This condition is termed ~Ifading~.
Normally changes in the propagation
en~ironment occur relatively slowly, i.e., over
periods of time ranging from several tenths
~l/lO's) of seconds to several seconds. However,
in a mobile RF environment, receivers (or the
corresponding transmitter~) often travel over some
distance in the course of receiving a message.
Because the signal energy at each receiver is
determined by the paths that the signal components
take to reach that receiver, the relative motion
bQtwe~n the receiver and the transmitter causes
~ the receiver to experience rapid fluctuations in
signal energy. Such rapid fluctuations can result
in the loss of data if the amplitude of the
. received signal falls below the sensitivity o the
recei~er. .
Over small distances, the signal components
that determine the composi~e signal are well
correlated, i.e., there is a small probability
that a significant change in the signal power
e~velope Will occur over the distance. If a
transmission of a data packet can be initiated and
completed before ~he relative movement between the
receiver and transmltter exceeds the "small
distance", data loss to fading is unlikely to
OGCUr~. The maximum "small distance" wherein a
SUBSTITUTE SM~ET (RULE 26)
:
W094/10774 ~ ~1 PCT/~S93/1052
high degree of correlation exists is referred to
hereafter as the "correlation distance".
' As expressed in wavelength~ of the carrier
fre~uency, the corxelation distance is one half
(l/2) of the wavelength, while a more conservative
value is one quarter tl/4) of the wavelength.
Taking this correlation distance into
consideration~ the ~ize of the data pa~ket for
segmentation purposes can be calculated. For
example, at 915 ~H~ (a prefe~red RF transmission
frequency) j a quarter wavelength is about 8.2
centimeters . A mobile radio moving at ten ( 10)
miles per hour, or 447 centimeters per sec:ond,
. travels the quarter wavelength in about 18.3
milliseconds. In such an en~ironment, as long as
the se~ment packet siz~e remains well under 18.3
. milliseconds, significant signal fluctuations
. ~ during the duration of a packet transmission is
:~ : unlikely.~ In such an preferred embodiment, fi~e
20(5) millisecond data packet ~egments are cho~en
: which ~ provid~s~ a quasi-statlc multipath
communicat on environment~
~ l ` The faster the relative moYement between a
: ~ transmitter and a~receiver the greater the effect
: : 25of fading, and, therefore, the smaller the data
~ : ~ : :
: ~ segment should be. Similarly, if the relatiYe
. :movement is slower, the data segment can be
larger.
:
SUBSTITUTE SHEET (RUL~ 26)
` '
W~94~10774 2 1 4 8 3 8 1 PCT/US93/10528 _ :
34 :~
Slower fading effec~s which might be
experienced between stationary transceivers in an
office huilding due to thP mov~ment of p20ple,
mail cart~, and the like. In a typical
applîcation of the present invention, the RF
transc~iver of a mobile unit may be secured with
¦ a bar-code scanner such as a deflected laser beam
bar-code scanner or an instant CCD bar-code
~ s~anner. In such an example, the bar code data
¦ lO could be transmitted to the base station as the RF
transceiver ~nd a ~canner device were being
jointly transported by a vehicle (e.g. a forklift
truck~ to another site~ or the RF transceiver and
a ~canner, e.g. as a unitary band-held device,
could be carri~d by th~ operator to another site
as the bar code ~ata was being transmitted to the
base station. In such situations, fading is more
pronounced~
I~ fading does not pose a problem on a given
network, the overhead associated with
segmentation, handwshaking and reconstruction may
not be justi~iable. Howe~er, where fading exists,
such~overhead may be required.
In many commun}cation environments, the
: ~5 degree of fading effects varies dramatically both
from t~me to time and from installation to
insta~lation. In the preferred embodiment,
: transmitters and receivers communicate using an
optimal data se~ment size parameter by adapting
:
3 (Pll~L~
W094/l0774 ~3~1 PCT/US93/lG528
the size to conform to the communication
envi~onment of the network at any given time. For
example~ if a receiver detects repeated faulty
i transmissions, the data se~ment size parameter
might be incrementally reduced (under the
assumption that fa~ing caused the faults) until
the data throughput reaches an optimal level,
Similarly, the size of the data segment can be
reduced based~ on a measured indication of the
degre~ of fading in the network.
One example of a receiver making such a
measurement of fading can be found in the
aba~doned patent application of Ronald L. Mahany,
- U.S. Serial No. 07~485,313, filed February 26,
j 15 1990. Specifically, in that reference, a receiv~d
, signal strength indicator (RSSI)~circuit is found
:! in the receiver. ~The RSSI circuit samples the
signal strength of a transmission. If the signal
. ~trength samples are evaluated in sequence and the
trend analyzed~ the degree of fading can be
measured. If thè signal strength samples
decrease in value, it is likely that fading is
present' in the network. However, just beJause
fading e~ists do~s not ~equire segmentation. Only
if fading causes the signal strength to drop balow
the level of the receiYer ' s sensiti~ity i5
segmentation required.
A fixed~ threshold value that is located a
.
~ safe margain above the receiver's sensitivity is
.
~ ~ t ~ t; ~ 2~ ~
wo g4/l0774 2 1 4 8 3 g 1 PCT/US93/1~52~
36
used to determine whether to change the data
segment size. ~f a trend in signal strength
shows values falling below the threshold, ~he
data segment size is decreased. I~ the threshold
S level is never reached, the segment size might be
increased. In addition, the trend associated with
a gr~up of signal strength samples can be used to
predict the optimal data packet size -- th~
intersection of the signal strength samples with
the threshold defines a s gment length that, with
a safe margain, can be used effectively used;with
the current degree of fading.
After receiving a data segment, the receiver
sends to the transmitter indications regarding: l)
whether the data segment was received without
fault; and 2~ what the new optimal se~ment size
~hould be. The transmitter responds ~y ad~usting
. the data segment .size and then sending the.next
segment. As can be appreciated, the data segments
are adapted based on the prPvious transmi~sion.
Instead of adjusting on the basis of the reception
of a sin~le data segment (the previous
~ransmission), other techni~ues for adju~tmen~ are
contemplated. For example, the transmitter may
al~o utilize a threshold window (or weighted
averaging), inside of which the segment siz~ will
: not be changed. ~nly if the reque~tPd change by
the receiver falls outside of the ~hreshold window
- will the segment size change. Similarly, the
iS ~ E S!A~ T i~ 2~) -
094/]0774 21 ~ 8 3 81 PCT/US93/10528
receiver might also utilize such a window -- only
requesti~g a change when the newly forecasted,
` optimal segment size falls outside of the window.
Direct-Seauence Spread S~ectrum Parameters.
As described above, the network controller :~
prQvide~ an interface to both the older generation
UHF radio transceivers and newer generation spread
spectrum transceivers. A spread spectrum
broadcasting system uses a sequential pseudo=noise
signal to spread a signal that is in a relatively
narrow band~over a wider range of frequencies. Tt
is the subject~of~standards issued by the Federal
Communications Commission (FCC) ~hat provide
usable spectrum at low power le~els for
~5 communication in:limited areas~such as warehouses,
. office buildings, and the like. The use of
!
spread-spectrum techni~ues minimizes interference
with others using the same channels in the
: spectrum.
: :
A tran mitter using direct-sequence spread
spectrum transmission uses a spreading code of a
: ~ higher frequency than that of the data rate to
:, encode the data to be sent:. This higher ~requency
I .
is achieved by increasing; the chip clock rate
(wherein each chip constitutes an element of the
spreading-code). Using the same spreading codel
the rece:iver d codes the received signal while
:
ignoring minor faults which occurred in
`
~ ~ t~Sw~ L~ ~6)
WO94/10774 PCT~U$93/105~8
transmi~sion, providing noise immunity and
multipath signal rejection. The frequency and
length of the spreading code can be varied to
offer more or less multipath signal rejection or
noise immunity. Although it may result in
improv~d communication, increasing the frequency
or length of the spreading-code requires
additional overhead which may not ~e justifiable
unless necessary.
Frequency~Hoppinq Spread S~ectrum Parameters.~
Frequency-hopping is the switching of
tr~nsmlssion frequencies according to a ~equence
that is fixed or pseudo-random and that is
available to both the transmltter and receiver.
lS Adaptation to the communication environment via an
exchange in frequenzy-hoppi~g operating parameters
is possible, for example, via selective control of
the hopping rate or through the use of coding or
interleaving. The greater the degree of frequency
selectlvity of the fadiny envelope (i.e., when
fading is significant only over a portion of the
spectrum of hopping fre~uencies3, the greaterlthe
benefit of sUch adaptation.
Particular~y, a parameter indicating the
hopping rate can be varied to minimize the
probability that the channel characteristics will
detrimentally ~hange during th2 course of a
communication exchange. To vary the hopping rate
~ '
~s ~r~ L ~ ~P-r (~ &~
W094/10774 2l ~838l PCT/US~3/10528
39
is to vary the length of a hopping frame.
Although multiple data (or message) exchanges per
hopping frame is contemplated, the preferred
hopping frame consists of a single exchange of
data. For example, in a polling environment, the
hopping ~rame might consist of: 1) a base station
transmitting a polling packet to a roaming
terminal; 2) the roaming terminal transmitting
data in respvnse; and 3) the base station
responding in turn by transmitting an acknowledge
packet. Each hopping frame exchange occurs;at a
different pseudo-randomly chosen frequency.
For optimization, the hop ~rame length is
adjusted to be as long as possible, while
remaining shorter than the coherence time of thP
channel by some safety maryin. Although such
:~ adjustment: does ~ot eliminate the effects of
fading, it increases the probability that the
characteristics of the channel will remain
consistent~during each:hopping frame. Thus, in
the preferred embodiment, if the polling pa ket
::
transmission is suacessfully received, the
~` probability of successful receipt of the data (or
message) and ack~owledge is high.
: : .
~:~ 2S ~Another parameter for changing frequency-
: hopping performance is that of coding. Codin~ ~n
the channel ~or error correction purposes can ~e
selectively used whenever the probability of data
or message 10s5 due to fading is high. In
:~ .
: ~ :
WO94/1~7742 ~ ~ g ~ 8 1 pCT/~93/10528
particular, coding methods which provide burst
error correction, e.g., Reed-Solomon coding, can
be applied if the hop length is likely to exceed
the coherence time of the channel. Such coding
methods a1low some portion of the data to be lost
and reconstructed at the expense ~f a 30-50%
reduction in throughput~ ~he operating parameter
~or coding indicates whether coding sh~uld be used
and, if so, the type of coding to be used.
lOAn operating parameter indicating whether
interleaving should be used also helps to opt1mize
the cummunication channel. Interleaving involves
breaking down the data into segm~nts which are
~ redundantly transmitted in different hopping
frames. For example, in a three segment exchange,
the first and second segments are sequentially
combined and sent during a first hopping frame.
In a subsequent hopping frame, the second and
third segments are combined and sent. Finally,
the third and first segments are sequentially
combined and transmitted in a third hoppiny frame.
The recei~ing tr~nsceiver compares each segment
received with the redundantly r~ceived se~ment to
Yerify that the transmission was successful. If
.
errors are detected, further transmissions muist be
made until verification is achieved. Once
:achieved, the transceiver reconstructs the data
from the segments.
WO9~t~0774 1 ~ 381 PCT/US93/10528
41
Other methods of interlea~ing are also
contemplated. For example, a simpler form of
interleaving would be to sequentially send the
data twice without segmentation on two different
frequencies (i.e., on two successive hops).
As can be appreciated, interleaving provides
for a redundancy cbeck but at the eXpense of data
or message throughput. The interleaving parameter
determines whether interleaving is to be used and,
if so, the specific method of interleaving.
In addition, any combination of the above
frequency-hopping parameters might interact to
define an overall operating configuration,
different from what might be expected from the sum
of the individual operating parameters~ For
`~ example, selectin~ interleaving and coding,
~;; : : through their r~spective parameters, might result
in a more complex communication sc~eme which
: combines segmentation and error correctiQn in some
: 20 alternate fashion. ~
$ource _Encodinq Parameters I For _N~rrowband
A~lications~
In the ~United~ States, :data communication
equipment;operating in~ the~ ultra-high frequency
(U~F)~ ~ra~ge~ under~ conditi~ns of frequency
modulation: (FM? is~ subject ~to the following
limitations.
~ .
WC~ 9~/10774 ~ PCr/US93/10528
21 ~838~
42 :
( 1 ) The occupied }: and width is sixteen
kilohertz ~axi~um with fi~e kilohertz maximum
f re~uency deviation .
(2~ The c:hannel spacing is 25 kilohertz~
Tlhis requires the use of highly s~lected filtering
in the receiYer to reduce the potential for
interference from nearby radio equipment operating
on ad j acent channels .
(3) The maximum ou~put power is generally in
the range of tPn to three hundred watts. For
localize~ operation in a f ixed location, however,
transmitter power output may be ~limited to two
watts maximum, and limitations may be placed on -~
antenDa height as well. These restrictions are
inkended to limit system range so as to allow
ef~icient re-use of frequencies.
For non-return to zero (Nl~Z) data modulation,
the highest modulating ~requency is equal to one
~: : half the data rate in baud. Maximum- deviation of
~20 five kilohertz may be utilized ~for a highest
m~dulation~ fre~uency which is less than three
kilohertz, but lo~er deviations are general ly
required for hlgher modulation frequencies. Thus,
at a data ~ :rate of : ten thousand~ baud, and an
occupied bandwidth~ o~ sixteen kilohertz, the peak
FM deviation which can be utilized for NRZ data
~: ~ ; may be~three kilohertz or less,
ConElderations of cost versus performance
tradeo~fs are the major reason for the selection
~ : .
~ ~Z ~ nr~
~3 .~. ~.. .~v.
W094/10774 21~381 ~ PCT/U593/105~8
43
of the fre~uency modulation approach used in the
system. The approach utilizes shaped
non-return to-zero (NRZ3 data for bandwidth
efficiency and non-coherent demodu~ation using a
5 limiter-discriminator detector for reasonable
performance at weak RF signal levels. Howaver,
the channel bandwidth ~oonstralnts limit the
maximum data "high" data ra~e that can be utilized
for transmitting NRZ coded datas S~ignificant
improvements in system throughput potential can be
realized within the allotted ~ bandwidth~ by
extending~the concept of~adaptively selecting data
rate to inolude switching between sourc2 encoding
; methods. ~e~pr~eferred~approach is to continue to
15~ ~ use NRZ ooding f~or~the lower~system~data rate and
substitute~partia;l~response (PR~encoding for~the
higher; rate.~ The throughput~improvements of a
NRZ/PR s;oheme~over~an~NRZ~/NRZ~ mplementation are~
obtained~;~at the expense~of~additional complexity
in~thè~ aseband prooessing oircuitry.~
Partial ~rèsponse~encoding methods ~are line
coding~techniques which allow a potential doubling~
of the~data~rate over NRZ enooding uzing the~same
baséband bandwid~th. ~Examples~of PR encoding
25~ mèthods~include'duobina,ry and;modified~duobinary~
encoding.~ Bandwldth~ efficiency;~is improve~d~ by'
co'~verting~ binary~ ata into~ three level/ ~r
pseudo-ternary ~signals~. Beoause`~the receiver
decision circuitry~must distinguish;betweèn three
JE;~:~ll'uTE~SH,r~ RLLI: ~36) ~ -
W~94/10774 ,f.~l ~ &3 81 PCT/US93/10$~8
44 `
instead of two levels, there is a signal to noise
(range) penalty for using PR encoding. In an
adaptive baud rate switching system, the effects
of this degradation are feliminated ~ffy appropriate
selection of the baud rate switching threshold.
Since PR encoding offers a doubling of the
da~a ra~e of NRZ encoded da~a in the same
~andwidth, one possible~implementation of a NRZ/PR
baud rate switchiny system would be a 4800l9600
bit/sec system in which the low-pass filter
bandwidth is not switched. This migh!t be
desirable for example if complex low-pass filters
constructed of discrete components had to be used.
Use of a:single filter`could reduff~e circuit costs
l~ and printed:circuit board area requirements. This
approach might also be desirable if thfe channel
~:
bandwidth were reduced below what is currently ~.
: available. ~ ~
:~: The~ preferred ~ implementation with the -;
.:
bandwidth:available is to use P~ e~coding to
increase the high data rate wel1~beyond the 9600
bit/sec implementation previousl:y described. An
approach using 4800 bit/sec NRZ encoded data for
: ~ the low rate thereby~providing high reliability
and backward compati~ility with existing products/
~: : and~16R bit/sec~PR èncoded transmission for the
high ~rate:~may be utilized. The PR encoding
.
~ . ~ technique is a hybrid ~orm similar to duobinary
: and se~eral of its variants which has been de~ised
ff~s ~ ff~f-- ~ f~f~ ffr`)
WO94/10774 21~8~81 PcT/US93/10528
to aid decoding, minimize the increase in hardware
complexity, and provide similar performance
characteristics to that ~f the previously
described 4800/9600 bit/sec implementation. While
PR encoding could potentially provide a high data
rate of up to:20R bit/sec in the available channel
bandwldth, 16X bit/sec is preferab}e because of
the practical constraints imposed by oscillator
temperature stabil ity ~ and: the distortion
cha~acteristi~s of IF bandpass filters.
: Exchan~inq Parameters
All of the above re~erenced~parameters must
be maintained in local ~memory at both :the
:~ ~ transmitter and the~receiver so ~that successful
communication can occur. To change the~
communication envircnment~ by changing an Qperating
~` parameter~ requires both;synchronizati~n be~ween
~.
the transceivers and a method:for recovering in
case synchroni~zation fails.
2;0 ~ ~ In~:a preferred~emb~diment,~ if a transceiver~
: receiving a:transmission thereinafter referred to
as thè~"destination")~determines that an operating
parameter needs to be changed,~it must~transmit~a~
regues~t ~or change to~the~:t~ansceiver sending the
25 ~ transmission:~(berei~nafter~ the "source").: If~
` received, the ~ource~may~send an first acknowledge
to the destination: based on the current operating
paraoeter. Therean r, the sou-c- modif1es its
Tr ~r, J~
W~94J1~774 PCT/US93/1052
2`1`~'8381 46
currently stored operating parameter, stores the
modification, and awaits a transmission from the
de~tination ba~ed on the newly stored operating
i parame~er. The source may also send a "n~
acknowledge" message, rejecting the requested
modification.
If the first acknowledge message is received,
the destination modifies its currently stored
operating parameter, stores the modification,
sends a verification message based on the newly
stored:operating parameter, and awaits a second
acknowledge messa~e from the source. If the
desti~ation does not receive the first
acknowledge, the des~ination sends the request
againO If after several attempts the first
acknowledge is not received, the destination
modifies the currentIy stored parameter, stores
the modification as the new operating parameter,
I and, based on the new parameter, transmits a
,~ 20 request for acknowledge. If the source has
already made the operating parameter modification
(i~e~, the destination did not properly receive
' the first acknowledge message), the destination
receives the request based on the new parameters
and responds with a second ~cknowledge. After the
~; secon'd acknowledge is received, communication
between the source and destination based on the
: newly stored operating parameter begins.
:; '
`
S~ fP~ L~ c~
Pcr/uss3/los2s
~O94tl~77~ 381
If the destination does not receive either
the first or the second acknowledge mPssage~ from
the source after repeated requests, the
destination ~eplaces the current operating
5parameter with a factory preset system-default
(which is also loaded upon power-up). Therea~ter,
using : the system-default, the destination
transmits repeated requests for a~knowledge until
receiving a response from the~source. The system- ;
10default parameters preferably define the most
robust configuration for communication.
If a~ter a time-out period the second request
for acknowledge bas~d on the newly stored
operating parameters is not received, the source
:: 15restores the previously ~ modified operating
parameters and listens~ for a request fGr
~ acknowledge. If after a further time-out period r'
j~ a request ~or: acknowledge is not received, the
``: ~ source replaces the current operating parameter
; : 20with the factory prese~ system-default (which is
: ~ ~ the same as ~hat stored in:the destination, and
which is also loaded upon power-up~. Thereafter,
using the ~common sy~tem-default, ~the sourcè
: ~ listens~ for an acknowledge~ request ~rom the
25~ destination.~ Once~received, communication i5 re-
established O
; Other~ synch~ronization~ and recovery methods
are~also ~contemplated. For example, instead of
:acknowledge requests originating solely from the
WO94/1~774 . ;`` PCr/US93/10528
2 14 8 3 ~ 1 !
48
destination, the ~ource might also participate in
such requests. Similarly, although polling is the
preferred protocol for carrying out the
communication exchan~es described above, carrier
sense mu1tiple-access (CSMA~ or busy tone
protocol~ mi~ht also be used.
As is evident from the description that is
provided above,~ the implementation of the present
invention can vary greatly depending upon the
desired goal of the user. ~owever, the scope of
the present invention is intended to cover all
variations and æubstitutions which are and which
may become apparent from the illustrative
- embodiment of the present invention that is
15 provided above, and the scope of the invention
should be extended to the claimed invention and
its equivalents. It is to be understvod that many
:
variations ~nd modifications may be effected
.
without departing from ~he scope~of ~he present
; disclosure. ~: ~
:
:
~: ~ . . ;
.
:
,
S'` G~ E I (R~LE 2~)
