II 1111111111111
`
`US005696903A
`[11) Patent Number:
`[451 Date of Patent:
`
`5,696,903
`Dec.9, 1997
`
`United States Patent [19J
`Mahany
`
`[54] BIERARCIDCAL COMMUNICATIONS
`SYSTEM USING MICROLINK, DATA RATE
`SWITCHING, FREQUENCY BOPPING AND
`VEIDCULAR LOCAL AREA NETWORKING
`
`[75]
`
`Inventor: Ronald L. Mahany, Cedar Rapids,
`Iowa
`
`[73] Assignee: Norand Corporation, Cedar Rapids.
`Iowa
`
`(21] Appl. No.: l36,413
`
`[22) Filed:
`
`Apr. 29, 1994
`
`Related U.S. Application Data
`
`[63] Continuation-in-part of Ser. No. 197,386, Feb. 16, 1994,
`abandoned, which is a continualion-.in-part of Ser. No.
`168,473, Dec. 16, 1993, abandoned, which is a continuation(cid:173)
`in-part of Ser. No. 147,377, Nov. 3, 1993, abandoned, which
`is a continuation-.in-part of Sec. No. 101,254, Aug. 3, 1993,
`abandoned, which is a conlinuati.on-.in-part of Ser. No.
`85,662, Jun. 29, 1993, abandoned, which is a continuation(cid:173)
`in-part of Sec. No. 76,340, Jon. 11, 1993, abandoned, which
`is a continuation-in-part of Ser. No. 62,457, May 11, 1993,
`abandoned.
`lnL Cl.6
`...................................................... G06F 17100
`[51]
`[52] U.S. Cl. . ........................................................ 395/200.58
`[58] Field of Search ............................ 364/514 R, 514 C;
`370/85.9; 375/202; 379/58. 59. 60; 455/63.
`134; 3401131. 825.44
`
`[56]
`
`References Cited
`
`U.S. PATENf DOCUMENrS
`
`4,639,914
`4,807;2.'12.
`5,008,833
`5,070,536
`5 ,077,830
`5;2.45,051
`5;2.52,979
`5 ,337,044
`
`1/1987 Wmters .................................. 370185.9
`2/1989 Amitay ................................... 3 70/85.9
`4/1991 Eiuahofer et al .................... 370/95.1
`12/1991 Mahany et al ............................ 455/63
`12/1991 Mallia ....................................... 455/63
`911993 Mahany .................................. T/5/S(X)
`10/1993 Nysoo ....................................... 455/63
`8/1994 FOlger et al .
`...................... 3401825.44
`
`Primary Emminer-Ellis B. Ramirez
`Anom~ Agefll, or Firm-Stanford & Bennett L.L.P.
`[57]
`ABSTRACT
`
`A hierarchical communication system is described in which
`two wireless local area networks exhibiting substantially
`different characteristics are employed to link inbaendy
`portable or mobile computer devices. A series of radio base
`stations make up a infrastructure network. The infrastructure
`network and at least one portable computer device make up
`the first local area network. The communication on the first
`local area network is accomplished by spread spectrum
`frequency hopping communication. A second local area
`network. allows for radio communication between a portable
`computer device and peripheral devices with built-in trans(cid:173)
`ceivers utilized by the portable computer device. The com(cid:173)
`munication in each local area network is controlled by a
`reservation access communication protocol. The communi(cid:173)
`cation protocol facilitates frequency hopping synchroniza(cid:173)
`tion and supports adaptive data rate selection based upon the
`quality Qf communication on the communication channel.
`The communication protocol prevents interference between
`communication on the fust local area network and commu(cid:173)
`nication on the second local area network. In a premises
`LAN, a series of radio base stations and a backbone LAN
`make up an infrastructure network. The infrastructure net(cid:173)
`work and at least one mobile computing device make up a
`higher-power LAN. utilizing a frequency hopping protocol.
`A lower-power LAN allows for radio communication
`between a mobile computing device and peripheral devices.
`utilizing a single-frequency spread spectrum (K'Otocol. A
`vehicular LAN provides for short-range communication
`between a vehicle terminal and a portable terminal. When
`out of direct RF range of the premises LAN. the vehicle
`tctminal maintains indirect communication when necessary
`with the premises LAN via one of several alternate RF
`channels. A Inicroprocessor, located inside radio units which
`participate in multiple LAN's, selects the appropriate
`protocol. frequency band and power level for communicat(cid:173)
`ing through the network.
`
`56 Claims, 53 Drawing Sheets
`
`56
`
`57
`
`58
`
`59
`
`M CD • MOBILE COMPUTING DEVICE
`
`P ~ PERIPHERAL DEVICE
`
`APL 1010
`IPR of U.S. Pat. No. 6,128,290
`
`0001
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 1 of 53
`
`5,696,903
`
`0 -
`
`l() -
`
`N
`N
`
`~
`N
`
`~
`
`l() -
`
`flO
`~
`QJ
`
`I-I = co ·-~
`
`l() -
`
`l() -
`
`l()
`
`....
`
`1.0
`
`....
`
`0002
`
`

`
`33
`
`34
`
`HOST
`COMPUTER
`
`Second Local
`Area Network
`(Microlink
`Network)
`41
`
`....__ __..
`
`45
`
`0 •
`00
`•
`;:'
`.......
`~ a
`
`w
`.. ~.e
`.....
`~
`
`~
`!
`~
`~
`U'l w
`
`(It "' \C
`
`Q\
`~ \C
`Q
`~
`
`First Local A rea
`
`- - - -
`Ne'fr~/
`
`BASE
`STATION
`
`30
`
`Second Local
`Area.Nelwolk
`
`I
`~ I
`/----f;
`( B~
`
`/
`
`(
`
`M C D
`
`(Microlink
`Network)
`40
`
`0003
`
`~
`
`M C D = MOBILE COMPUTING DEVICE
`
`P =PERIPHERAL DEVICE
`
`Figure lb
`
`

`
`L! •
`00
`•
`~
`[
`
`~
`
`w
`~
`
`en
`c:r
`!l
`~ a,
`
`(,h
`~
`
`(11
`-.
`~
`\C
`~ -.
`
`\C = w
`
`so
`56 ~ 57
`(
`(
`
`HOST ~55
`COMPUTER
`
`58
`{
`
`5 9
`(
`
`BASE
`STATION
`
`BASE
`STATION
`
`BASE
`STATION
`
`~
`
`BASE
`STATION
`
`I \
`61 1 !\
`0 0 0
`
`I
`I
`0
`
`(IMcol ~62 ~63 64~ ~65 ~ 66
`
`I \
`\
`I!\ I
`0 ~ 0
`0
`
`0004
`
`M C 0 = MOBILE COMPUTING DEVICE
`
`P = PERIPHERAL DEVICE
`
`Figure lc
`
`

`
`U.S. Patent
`
`Dec.9, 1997
`
`Sheet 4 of 53
`
`5,696,903
`
`....-.....
`
`en --o
`(U_
`c:cn
`0 -.:::< Q.:E
`Oo
`1-
`
`....--.....
`
`U) c::
`.2
`en
`en
`4)
`(J)
`
`.,..,--
`
`.,..,--
`
`c:
`0
`;4 )
`tU0
`~as
`
`l).c U)n..
`CD a:
`
`0 z
`> en
`
`0005
`
`

`
`~ •
`00
`• ;p
`~
`
`\C
`"'
`
`w
`~
`
`~
`3 ....
`s,
`
`(.h
`
`Ul
`~
`
`(It
`
`...
`~ -....c
`~ ...
`-....c
`0
`~
`
`10 ms
`
`10 ms
`
`10 ms
`
`10 ms
`
`10 ms
`
`10 ms
`
`10 ms
`
`10 ms
`
`Freq. 1
`2466 MHz
`
`Freq. 2
`2411 MHz
`
`Freq. 3
`2417 MHz
`
`Freq. 4
`2472 MHz
`
`Freq. 5
`2444 MHz
`
`........... .....
`
`Freq. 79
`2403 MHz
`
`Freq. 1
`2466 MHz
`
`I
`301
`
`I
`
`301
`
`I
`301
`
`I
`301
`
`I
`301
`
`J
`' 301
`
`301
`
`Figure 3a
`
`0006
`
`20ms
`
`20ms
`
`20 ms
`
`20 ms
`
`20 ms
`
`20 ms
`
`20 ms
`
`20 ms
`
`Freq. 1
`
`2466 MHz
`
`Freq. 2
`2411 MHz
`
`Freq. 3
`
`Freq. 4
`
`2417 MHz
`
`2472 MHz
`
`Freq. 5
`2444 MHZ
`
`...............
`
`Freq. 79
`
`Freq. 1
`
`2403 MHz
`
`2466 MHz
`
`I
`'
`303
`
`I
`303
`
`303
`
`I
`I
`303
`
`I
`303
`
`Figure 3b
`
`I
`303
`
`I
`303
`
`

`
`~ • 00
`•
`~ ~
`~ a
`
`:::0
`
`w
`~
`
`(1:)
`Cl"
`
`~ ....
`
`~
`~
`Ul
`1M
`
`til
`-.
`
`~ "" ~ -.
`\0 s
`
`Freq 1: 2466 MHz
`
`Freq 2: 2411 MHz
`
`Freq 3: 2417 MHz
`
`Freq 5: 2444 MHz
`
`AI. 1
`20 ms
`
`AI. 2
`20 ms
`
`AI. 1
`
`20 ms
`
`AI. 2
`20 ms
`
`AI. 1
`20 ms
`
`AI. 2
`20 ms
`
`AI. 1
`20 ms
`
`AI. 2
`20 ms
`
`401
`
`Figure 4a
`
`0007
`
`Freq 1: 2466 MHz
`
`Freq 2: 2411 MHz
`
`AI. 1
`20 ms
`
`AI. 2
`20 ms
`
`AI. 3
`20 ms
`
`AI. 4
`20ms
`
`AI. 1
`20ms
`
`AI. 2
`20 ms
`
`AI. 3
`20 ms
`
`AI. 4
`20 ms
`
`I
`
`I
`
`I
`I
`
`401
`
`Figure4b
`
`

`
`0 • 00
`•
`~
`"""'" ~ a
`
`~
`...
`\C
`~
`
`~
`
`r:n c:r
`
`~ -.......
`
`0 ....,
`
`501
`
`SYNC
`
`Res. Poll
`
`Slot 1
`
`Sessions
`
`Optional
`TDMA Slots
`
`Figure Sa
`
`503
`
`0008
`
`SYNC
`
`Res. Poll
`
`RFP
`Addr 65
`
`Sessions
`
`Optional
`TOMA Slots
`
`Figure Sb
`
`U'l
`~
`
`Ol
`....
`Q\
`\C
`Q\
`....
`\C
`8
`
`

`
`0 •
`00
`•
`
`~ = f"'f" a
`
`\C
`
`w
`..
`~
`
`00
`
`t:r a
`g,
`
`00
`
`Ul
`(M
`
`Ul
`~ =""
`\C
`...
`=""
`\C a
`
`601
`
`601
`
`601
`
`SYNC
`
`Res. Poll
`
`Slot
`1
`
`Slot
`2
`
`..... ~ ..
`
`Slot
`n
`
`Sessions
`
`Optional
`TOMA Slots
`
`603
`
`Figure 6a
`605
`
`Slot
`n
`
`Sessions
`
`Optional
`TOMA Slots
`
`\
`
`RFP
`Addr
`
`111 -RFP
`Addr
`02
`\ .
`
`SYNC
`
`Res. Poll
`
`RFP
`Addr
`19
`
`Slot
`2
`
`0009
`
`fiJ7
`Figure 6b
`
`

`
`~ • 00
`• ;p
`i
`
`~
`~
`..
`\C
`......
`~
`
`~
`
`~
`(Jl =-~ ...
`
`I
`
`\0
`~
`ll1l w
`
`SYNC
`
`Res. Polt
`
`RFP
`Addr
`65
`
`Sessions
`
`Optional
`TDMA Slots
`
`-
`
`[free]
`
`707
`)
`
`709
`)
`
`711
`)
`
`0010
`
`RR I Addr65 I Poll
`
`Poll
`Addr
`65
`
`Send
`First
`Packet
`
`Next
`
`I Poll I Addr 65 I Clear I
`
`Send
`Third
`Packet
`EOD
`
`Next
`
`Addr65
`Send
`Second
`Packet
`
`701
`
`703
`
`705
`
`Figure 7a
`
`713
`
`(It
`....
`~
`\C
`~ ....
`\C
`Q
`~
`
`

`
`0 •
`00
`•
`~ =
`~
`
`w
`:;e
`~
`
`r:n g
`~
`......
`¢
`~
`(II
`~
`
`0'1
`....
`~
`\C
`~ ....
`\C
`0
`~
`
`SYNC
`
`Res. Poll
`
`RFP
`Addr
`65
`
`Sessions
`
`Optional
`TDMA Slots
`
`723
`
`0011
`
`AR
`E..oJJ
`RFP
`Addr
`103
`
`Addr
`103
`Poll
`CP
`
`CP
`Send First
`Packet
`
`Addr
`103
`Poll
`Next
`
`CP
`Send Second
`Packet
`EOD
`
`Addr I CP
`
`Clear
`
`103
`Clear
`
`[free]
`
`721
`
`Figure 7b
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 11 of 53
`
`5,696,903
`
`r.n
`c:
`.Q
`r.n
`r.n
`Q)
`CJ)
`
`-.2c:
`
`en
`
`en
`
`-.2C'.I
`-.,2_.
`
`en
`
`0 a.
`~ .
`CD a:
`0 -
`-CD
`
`........._...
`
`0
`
`J:
`
`........._...
`
`(.)
`z
`>
`CI'J
`
`0012
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 12 of 53
`
`5,696,903
`
`, ........ <~~------ <!(}5
`
`'
`
`\-·\)t)l
`
`'
`
`9(,-5 ,.,.__,,
`
`901 ,/""-~
`
`'
`
`(
`
`' .. _; .... . .-\'
`
`'
`
`,·
`
`\
`9(),~
`
`I<igur.e <Jb
`
`0013
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 13 of 53
`
`5,696,903
`
`o·"'~~~~i~1 e~s$
`C"A\Y'!~~aga Af~s&s
`
`Areas C.Over~d 811
`Str9J~! Sa.$8
`.
`
`H.lilt
`
`figure 10
`
`0014
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 14 of 53
`
`5,696,903
`
`0015
`
`

`
`U.S. Patent
`
`Dec. 9, tm
`
`Sheet 15 of 53
`
`5,696,903
`
`~ ~
`
`~
`ns
`CD
`
`Q)
`U)
`ca
`CD
`
`I
`
`....
`~
`.6
`....
`~
`I
`............_..~
`!
`"i
`
`I
`
`z
`5
`• al •
`~
`:2 ·:;
`
`CD
`
`~
`....
`
`~ ca
`en
`
`~
`
`i
`
`~
`
`Q)
`UJ
`
`~
`
`0016
`
`N
`p-4
`....
`Ql
`:s
`01)
`
`·-"""
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 16 of 53
`
`5,696,903
`
`~
`
`.....
`
`......._.....
`
`G)
`CD
`
`~
`
`(/) - cu
`
`~
`......
`
`CD
`en
`~
`CD
`~
`§
`
`cD
`
`~
`.~
`
`I
`i
`"i ... . i
`I
`
`~
`
`-
`
`(f')
`.-4
`cu
`....
`~
`......
`~
`
`CD
`>
`.!!
`(/)
`
`-(#)
`
`....
`CD
`as
`~
`
`0017
`
`

`
`0
`• 00
`•
`1-d
`~
`""'"
`~ =
`""'"
`
`\C
`
`w
`..
`~
`
`~
`
`r:/.l
`
`~
`~
`
`=-
`
`-~ ...:a
`
`0
`~
`f.A
`~
`
`Ul
`Q\
`
`~
`
`\C "' ~
`\C 8
`
`1413
`(
`Portable
`Mobile
`Device
`.
`
`,..
`
`1409 v
`I
`
`1411
`____ _c_______
`1 Wireless
`Base
`
`1401
`
`: v
`
`1403 v
`
`1405 v
`
`Base
`
`I
`
`I
`
`Base
`
`I
`
`I
`
`Base
`
`I
`
`0018
`
`LAN
`
`1407
`
`Figure 14
`
`

`
`Optional
`TDMA Slots
`
`-c
`
`1501
`
`0 • 00
`• ;p
`....... a
`
`\C
`
`w
`..
`"""" ~
`
`rJ'j
`tr'
`~
`~
`"""" oc
`~
`Ul
`~
`
`Ul
`._.
`~
`\C
`~ ._.
`\C
`ffi
`
`1503
`
`1505
`
`_1
`
`l.
`
`1509
`
`SYNC
`
`Res. Poll
`
`Slot 1
`
`Sessions
`
`SYNC
`
`Res. Poll
`
`Slot 1
`
`Sessions
`
`.
`
`1507
`
`Figure 15
`
`11 Wired Base Station SYNC
`Microlink Master SYNC ===9
`
`0019
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 19 of 53
`
`5,696,903
`
`Initial Acquisition Algorithm
`Base Station Selected
`
`Mobile Computing Device (MCO)
`Registers with Appropriate
`Base Station
`
`MCO Monitors Communication
`Link Quality, And Stores
`Information Received From
`HELLO Messages Such As Costs
`of Connection And Frequency
`Hop Sequences
`
`Yes
`
`No
`
`Figure 16a
`
`0020
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 20 of 53
`
`5,696,903
`
`Yes
`
`Synchronization Attempted with
`Another Base Station, Selection
`Based on Lowest Cost of
`Connection
`
`New Communication Link Quality
`Monitored
`
`No
`
`No
`
`MCD Continues Monitoring
`Communication Link Until A
`HELLO Message ts Received From
`the Base Station
`
`No
`
`Figure 16b
`
`0021
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 21 of 53
`
`5,696,903
`
`Initial Synchronization,
`Coordinate with Priority
`SYNC
`
`Go To Sleep
`
`Wake Up And Wait To
`Receive Next Priority
`SYNC
`
`Stay Awake To Test
`Communication Urlk
`
`Yes
`
`Execute Roaming
`Algorithm
`
`Figure 17
`
`0022
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 22 of 53
`
`5,696,903
`
`Initial Synchronization,
`Coordinate with Priority
`SYNC
`
`Sleep A Long Time (e.g.,
`Seconds)
`
`Wake Up Short Time
`(e.g., 500 ~) Before
`Expected Beginning Of
`Access Interval
`
`Wait To Receive Next
`Priority SYNC
`
`No
`
`No
`
`Stay Awake To Test
`Communication Link
`
`Yes
`
`Figure 18
`
`Execute Roaming
`Algorithm
`
`0023
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 23 of 53
`
`5,696,903
`
`Transmit SYNC
`
`Transmit HELLO
`(Optional)
`
`Determine Extent Of
`Channel Traffic
`
`Heavy Traffic:
`n>1,p<1
`
`Transmit Reservation
`Poll, Including: n,p,
`Addresses With Pending
`Messages, Reserved
`IOMA
`
`Receive Requests For
`Poll's (RFP's) From
`Devices In Reservation
`Slots
`
`Reservation Resolution
`Poll:
`Place Addresses of
`ldentffied Devices In
`Polling Queue, Transmit
`Poll To First Unit In
`Polling Queue. Polling
`Queue Order Is:
`(1) Outbound Messages
`For Active Units
`(2) Units Requesting a
`Poll In Previous
`Access Intervals
`(3) Units Requesting A
`Poll In Current
`Access Interval
`
`Figure 19a
`
`0024
`
`

`
`U.S. Patent
`
`Dec.9, 1997
`
`Sheet 24 of 53
`
`5,696,903
`
`Wait For Response
`To Poll (Data
`Fragment)
`
`Transmit
`Poll To ~r-----.
`Same
`Address
`
`Addresses
`Remain In
`Polling Queue
`
`Figure 19b-1
`
`0025
`
`

`
`U.S. Patent
`
`Dec.9, 1997
`
`Sheet 25 of 53
`
`5,696,903
`
`Transmit
`~-..;1 Poll To
`Next
`Address
`
`Clear Message
`Transmitted, p ~ o.
`(Explicit Idle Sense)
`
`Clear
`Message
`Transmitted,
`p=o
`
`Figure 19b-2
`
`0026
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 26 of 53
`
`5,696,903
`
`Transmit SYNC
`
`Transmit HELLO
`(Optional)
`
`Determine Extent Of
`Channel Traffic
`
`Heavy Traffic:
`n>1,p<1
`
`Transmit Reservation
`Poll, Including: n,p,
`Addresses With Pending
`Messages, Reserved
`IDMA
`
`Receive Requests For
`Poll's (RFP's) From
`Devices In Reservation
`Slots
`
`n=1
`P<1
`
`n>1
`p:1
`
`Figure 20a
`
`0027
`
`Reservation Resolution
`Poll:
`Place Addresaes of
`Identified Devices In
`Polling Queue, Transmit
`Poll To First Unit In
`Polling Queue. Polling
`Queue Order Is:
`(1) Outbound Messages
`For Active Units
`(2) Units Requesting a
`Poll In Previous
`Access Intervals
`(3) Units Requesting A
`Poll In Current
`Access Interval
`
`

`
`U.S. Patent
`
`Dec.9, 1997
`
`Sheet 27 of 53
`
`5,696,903
`
`Wait To Receive Poll
`From Device
`
`"T-~ Address Remains In
`Polling Queue
`
`Send Data
`Fragment
`
`No
`
`Wait For Clear
`Message From
`Device
`
`Figure 20b-1
`
`0028
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 28 of 53
`
`5,696,903
`
`Device
`Address
`Removed
`From
`Polling
`Queue
`
`Device Address
`Remains In Polling
`Queue
`
`Transmit Request For
`PoU (AFP) To Next
`Device In Polling
`Queue
`
`Continue Inbound
`Algorithm:
`1) Transmit PoU
`2) Wait For Response
`To Poll
`
`Transmit Clear
`Message, p = o
`
`Transmit Clear
`Message, p ~ o.
`
`Figure 20b-2
`
`0029
`
`

`
`Optional
`TDMA
`Slots
`
`2113
`
`~ • \F.;.
`•
`~ = ....
`~ a
`
`w
`:;c
`"""' ~
`
`~ tl> ...
`
`N
`\Q
`~
`U1
`fM
`
`Ul "' \C
`
`~ ....
`\C
`ffi
`
`{
`
`2100
`
`SYNC
`
`Res.
`Poll
`
`s A
`I
`A
`0
`t
`s
`
`Poll
`Queue:
`Outbound and Slot
`Responses
`
`Explicit/Implicit Idle Sense Access
`
`..
`
`0030
`
`2101
`
`2103
`
`Figure 21
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 30 of 53
`
`5,696,903
`
`0
`Cl)
`CD
`0
`
`0 <
`CD
`fn c
`CD en
`
`CD , -·u -c.
`
`~
`
`E
`:::::
`~
`c.
`)( w
`
`CD
`::l
`-
`CD
`0
`Cl. ~
`0
`
`a: a:
`
`-
`
`C/)-0-(1)
`
`f-...-'
`
`ui=
`G) 0
`a: a.
`
`u
`z
`>(cid:173)
`en
`
`8
`~
`~ N
`
`N
`
`cu i ·-"""'
`
`s
`~
`
`~
`
`~
`
`0031
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 31 of 53
`
`5,696,903
`
`rn
`rn
`CD
`0
`0
`c(
`CD rn
`c:
`CD
`rJ)
`~
`
`1:J --......
`
`0
`Q.
`E
`:::::::: :::
`.2
`Q.
`)( w
`
`CD
`::::l
`0
`CD
`~ ~
`0
`
`a: a:
`
`~
`~
`
`~ ~
`
`tf')
`N
`ell
`...... :s
`....
`bD
`"-
`
`rn-o-U) ~ ~
`
`- -
`
`Ci<U)
`c:~-
`.2 0
`0
`Q. ~ rJ)
`0
`
`0=
`CD 0
`a:~
`
`u
`z
`>-
`rJ)
`
`~
`
`__.
`
`-
`
`0032
`
`

`
`e • 00 •
`;?
`...... a
`
`w
`
`y:'J
`~
`
`~
`
`~ 2400
`
`Figure 24
`
`~ ~ -~
`
`~
`~
`
`Ul
`-..
`~
`\C
`~ -..
`\C
`8
`
`SYNC
`
`Optional
`TDMA
`Slots
`
`Poll Message
`Queue
`
`Res.
`Poll
`
`s
`I
`0
`t
`8
`
`A
`R
`
`Poll Inbound Message Queue
`or
`Explicit/Implicit Idle Sense Access
`
`.
`
`.
`
`.
`
`2401
`
`2403
`
`2405
`
`0033
`
`

`
`~ •
`00 •
`
`~ ..... a
`
`~\C
`
`w
`~
`
`f'D
`
`r:J:J cr
`f'D ...
`~
`0 ....,
`0. w
`
`(I)
`
`~ "' \C "' ...
`
`\C
`
`8
`
`~")
`
`2501
`
`\
`
`Preamble
`....... 1 01010101010101010101010101010101010101010101010101010101010 .. .....
`
`2503
`
`2505
`
`\
`
`\
`
`SYNC
`
`Res. Poll
`
`~ 300 JLSec
`
`120 JLS ++
`
`110 J.I.S ++
`
`Training and Acquisition
`....
`++allows additional bit 1imes for HDLC zero bit insertion
`
`14 bytes
`
`12 bytes
`
`F req. Switching
`
`~ 150 J1S8C ~
`
`0034
`
`Figure 25
`
`

`
`SYNC
`
`f2600
`I
`
`Definition
`Frame Delimiter
`Destination Address (SYNC= Broadcast= FFFFH)
`Destination Address, 2nd Byte
`Message Type=SYNC, Priority Sync, or Priority SYNC with
`HELLO
`Control Point Address
`Control Point Address. 2nd Bvte
`System Identifier (LAN 10)
`Net 10
`
`ControlPoiot Status
`2 Bits Cu. "'u; Point Tvoe
`2 Bits
`loadino Factor
`.. ,.IM Service Availabilitv
`Scl'
`1 Bit
`3Bits Reserved
`Scheduled Services
`5 Bits Number of Allocated TDMA Time Slots
`3 Bits Number of Available Time Slots
`Randomlv C' -•
`.£ Character for lmoroved Encrvotion
`Error Ct"'ck
`Error Check
`Frame Delimiter
`Figure 26
`*Optionally Encrypted Bytes
`
`~ • CJ').
`•
`~
`[
`
`\0
`
`w
`..
`~
`
`~
`~
`~
`~
`~
`~
`
`(.1'1
`
`...
`~
`\0
`~ ...
`\0
`ffi
`
`I Bvte
`1
`2
`3
`4
`
`5
`6
`7*
`8*
`9*
`
`Content
`FLAG
`Dest. Address 1
`Dest. Address 2
`TYPE
`
`Source Address 1
`Source Address 2
`SYSTEMID
`NETID
`Command/Status 1
`
`10*
`
`Command/Status 2
`
`11*
`12
`13
`14
`
`Random
`CRC 1
`CRC2
`FLAG
`
`0035
`
`

`
`Reservation Poll
`
`~2700
`
`I
`
`Definition
`Frame Delimiter
`Destination Address (RES= Broadcast= FFFFH)
`Destination Address, 2nd Byte
`Message Type = RES POLL
`3 Bits Number of Slots
`5 Bits Probability Factor
`Hopping Sequence 10
`Hopping Sequence Index
`
`3 Bits Hop Rate
`2 Bits Al's per Hop
`3 Bits Reserved
`
`Figure 27
`
`Error Check
`Error Check
`Delimiter
`
`....
`ru-trnH
`
`~ • fJj
`•
`~
`~
`
`0
`
`~ .. ~
`~
`
`00
`cr
`~
`
`~ ...
`w
`tTl
`~
`~
`
`til
`._..
`~
`\C
`~ ....
`\C
`Q w
`
`Byte
`1
`
`2
`3
`4
`5
`6
`
`7*
`a·
`g•
`
`10
`
`11
`
`12
`
`Content
`FLAG
`Dest. Address 1
`Oest. Address 2
`TYPE
`SLOTPARMS
`
`Sequence
`Index
`NET PARMS
`
`CRC 1
`
`CRC2
`FLAG
`
`0036
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 36 of 53
`
`5,696,903
`
`0 -0 ,.,
`
`o--0 ""
`
`r--.
`-
`0~
`
`-3
`-
`0
`,.,
`
`<(
`co
`N
`CD ·-LL
`•
`
`7--L------- -, =ol
`=o
`=o
`
`I
`I
`I
`I
`I
`I
`I
`I
`I
`'-----------....1
`
`,., -0 ,.,
`
`0037
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 37 of 53
`
`5,696,903
`
`r ----------~
`I
`I
`I
`I
`L ---------...J
`
`, ,
`0 ,
`
`.Q
`co
`N
`•
`
`t7) ·-LL
`
`, -0 ,
`
`r(cid:173)-
`:~-------,
`I '==[]
`I
`I
`==ol
`I i ==[]
`
`1
`I
`I
`
`I
`1
`I
`
`I
`I
`I
`
`I
`I
`I
`
`I L--- -- ---- - -1
`
`0038
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 38 of 53
`
`5,696,903
`
`0039
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 39 of 53
`
`5,696,903
`
`0 -0
`
`"'
`
`(7)
`('I
`
`• en ·-LL.
`
`,..._ -0
`:~--------,
`I =[]
`I
`I =o l
`I
`I
`I
`' ==[]
`I
`I
`I
`I
`I
`:
`L---------- _J
`
`I
`I
`I
`
`I
`I
`I
`I
`
`I
`I
`I
`
`0040
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 40 of 53
`
`5,696,903
`
`"
`
`,
`
`L4.J
`
`u < u...
`.._
`0:::
`LU
`z
`-
`
`............
`
`r---....
`
`r-
`
`~ II'
`
`t
`
`'
`
`0
`M
`
`• C) ·-u..
`
`0::
`0
`V)
`V')
`LU
`u
`0
`a::
`a.
`0
`0::
`-
`u
`~ ~
`0
`~
`~
`m
`
`0 -0 < 0::
`
`m ...-...... ,.,
`
`r-J. v
`
`vi f-..
`~
`....,
`r--
`Vl
`a:
`0
`0
`<
`
`~
`
`j
`
`~
`
`.,.
`
`- - ~
`
`r
`~·
`C~V)V')0
`X
`1 - t -U
`1-0::0::UCl
`
`0
`N ..-
`m
`
`- ............
`
`....
`
`N --,.,.,
`
`0041
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 41 of 53
`
`5,696,903
`
`-I ' -,
`
`~
`M
`
`• m ·-LL
`
`r
`
`0042
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 42 of 53
`
`5,696,903
`
`Fig. 32
`
`3181-_, MESSAGE
`TO SEND
`
`WAIT FOR
`IDLE
`SENSE SlGNAL
`
`3183
`
`NO
`
`~3180
`
`r----3187
`
`EXECUTE
`BACK-OFF
`PROTOCOL
`
`NO
`AITEMPT
`TRANSMIT
`
`YES
`
`YES
`
`3189
`
`3191
`
`3193
`
`TRANSMIT
`MESSAGE
`
`3195
`
`0043
`
`

`
`U.S. Patent
`
`Dec. 9, 1m
`
`Sheet 43 of 53
`
`5,696,903
`
`3205
`
`3201
`rf
`~
`32oL 609
`
`3207
`!_
`
`(3211
`
`3205
`( 3227
`
`3207
`)
`
`,3205
`
`3207
`(_
`
`3205
`
`6
`
`m~
`f
`12 ~21
`
`3219
`
`3223
`
`r:;=3225
`
`3217
`
`3215
`
`b213
`
`I
`Fig. 33a
`
`3205 ..... 3 322r, e233
`
`tl
`
`3237
`. ~ )
`0:: ':1 ~ tJ
`
`3205
`
`3205
`
`I tf@Ja
`
`0
`
`Fig. 33b
`
`3231
`
`3205
`
`3231
`
`3233
`
`3209
`
`3211
`
`321s Fig. 33c
`
`•••
`
`0044
`
`

`
`•
`
`0 • 00
`1-C = ~ a
`
`,.IJ:)
`
`w
`~
`
`tr.J go
`~
`t
`~
`~
`
`(It
`~
`\C
`~
`\C
`6
`
`~
`
`1
`
`'
`I
`I
`I
`1
`
`I
`I
`I
`
`11
`
`
`
`
`
`c.m.5.8:»:2.e.532.8.ta.3m.%%.8
`
`3261 ::J ~ 3269
`]~ - ~ ~3261
`~ ; - )
`_ . l l .L .__ _ _jf-1
`m
`3251
`_{_
`--- -- -- --- - --- - -- -l
`r:-- --- v 3273
`32~--- 1
`o , o 1
`n
`1 o 1
`
`I
`I
`I
`I
`1
`1
`I
`I
`1
`1
`I
`1
`I
`I
`I
`1
`.
`I
`I
`I
`I ~~ I
`3 67
`I
`1 [] I
`J
`I
`I
`I
`1
`I
`t
`I
`~... ___ _~
`L - - - - -
`L--- - ---- ------ ----- -- - ----- - ---- - ------ - J
`n
`~ n
`
`3257
`
`\_ ~
`
`32.61
`
`3253
`\
`
`{-3261
`
`- - - - - - - - - - - - - - - -
`r -
`3)265 3~~3271
`1 3263
`'--Lr]
`1
`
`I
`I
`I
`1
`
`3255
`
`3265
`J
`
`3259
`
`0045
`
`r
`
`~
`
`3271
`[)
`
`I 3251
`
`1 ~
`
`Fig. 34
`
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 45 of 53
`
`5,696,903
`
`UPON RECEIVING
`A TRANSMISION
`FROM
`MICROLAN DEVICE
`
`3311
`
`/3301
`
`IDENTIFY A
`ANGEVALUE
`
`3313
`
`~3303
`
`-__,..,....,~~~,.....,....,...- 3314
`SUBSEQUENTLY,
`TRANSMIT RANGE VALUE
`TO THE
`MICROLAN DEVICE
`
`UPON RECEIVING
`A RANGE VALUE
`
`3321
`
`3323
`
`USING BATTERY
`PARAMETERS, IDENTIFY
`SUBSEQUENT DATA RATE
`(AND POWER LEVEL)
`
`3325
`
`SUBSEQUENTLY,
`TRANSMIT INDICATION OF
`IDENTIFIED DATA RATE
`(EXPLICIT /IMPLICIT)
`
`Fig. 35
`
`0046
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 46 of 53
`
`5,696,903
`
`Fig. 36
`
`UPON BINDING
`(AND PERIODICALLY)
`
`/3351
`
`;
`
`3353
`.----~--.1...
`TRANSMIT INDICATION
`OF BATIERY
`PARAMETERS
`
`3358
`
`UPON RECEIVING A
`TRANSMISSION FROM
`MICROLAN DEVICE
`
`3355
`UPON RECEIVING
`BAmRY PARAMETERS
`FROM A MICROLAN
`DEVICE
`
`3359
`
`BASED ON RANGE AND
`USING STORED BA TIERY
`PARAMETERS, IDENTIFY
`SUBSEQUENT DATA RATE
`(AND POWER LEVEL)
`
`SUBSEQUENTLY, TRANSMIT
`INDICATION OF
`IDENTIFIED DATA RATE
`(&POWER LEVEL)
`TO MICROLAN DEVICE
`
`STORING THE
`BAmRY
`PARAMETERS
`
`3361
`
`0047
`
`

`
`13501
`
`3503
`
`Control
`Processor
`
`Memory
`
`3522
`
`3523
`
`Power
`Source
`Control
`
`~ •
`00
`•
`~ f"'t'
`~ a
`
`::0
`
`w
`~
`
`ga
`~
`~
`~
`~
`
`(h
`~
`
`,..
`tit
`~
`\C
`~ ,..
`
`\C e
`
`3511
`
`( 351J7
`
`'
`
`Transmitter
`1 Amplifier
`
`3505
`
`Modulation
`Encoding
`
`3515
`
`(
`
`Antenna
`Switching
`
`Frequency
`Generator
`
`3509
`
`3513
`
`(
`•
`••
`
`0048
`
`,
`
`C>l Receiver RF •
`Processing
`
`,.
`
`Receiver
`Signal
`Process in
`
`3517
`
`3521
`
`Figure 37
`
`

`
`U.S. Patent
`
`Dec.9, 1997
`
`Sheet 48 of 53
`
`5,696,903
`
`~
`~
`
`....
`~ ('!")
`'-0
`(.) >
`
`~
`
`-....
`
`\l)
`('!")
`
`LL. w a:
`....
`
`z
`;.
`
`t--.
`
`~
`
`LL a..
`
`..J
`
`c e
`
`a:
`;.
`
`ao
`~
`Ql
`J-c
`
`~ ....
`
`~
`
`CD
`
`._
`
`i~ ... -CD ·(cid:173)_u
`£~
`
`0049
`
`

`
`5,696,903
`U.S. Patent
`r----------------------------------1
`
`Dec. 9, 1997
`
`Sheet 49 of 53
`
`I
`
`Preselector
`
`(
`
`3651
`
`I
`1
`I
`I
`I
`I
`I
`I
`I
`
`I
`I
`I
`I
`I 3653
`I (
`
`n
`•
`• ~3657
`•
`n
`
`----1>
`
`4
`
`( 3655
`
`( 3659
`
`. ..
`;:. Switching >--~ I
`I
`I
`I
`~ ~ I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`I
`1----------------------------------~
`Figure 39
`
`Figure 40
`
`0050
`
`

`
`~ •
`00
`•
`~
`~
`
`~
`
`0
`~
`~'~:>
`
`~
`
`~
`
`r.n =-f'D
`f'D -lll
`
`0
`0
`~
`lll
`(M
`
`~
`
`tit
`Q\
`\C
`Q\
`~
`\C
`
`ffi
`
`~---------------------------------------------------------,
`3765
`
`I
`
`1>1~
`
`AID
`Converter
`
`3769
`
`3773
`
`SIN
`
`fREF
`
`------
`
`Digital
`Signal
`Processor
`
`90°
`
`3763
`
`cos
`
`3767
`
`3771
`
`I bi~
`
`AID
`Converter
`
`3775 1
`
`3751
`
`3753
`
`3755
`
`n
`
`0051
`
`~---------------------------------------------------------~
`· Figure 41
`
`

`
`U.S. Patent
`
`Dec. 9, 1997
`
`Sheet 51 of 53
`
`5,696,903
`
`Routines
`
`, / ' 3522
`
`3823 - "' MAC Select/Service
`r----------- -~
`
`3819
`
`~ Common Mac
`1
`:
`Routines
`1
`------------~-
`
`3811 -
`
`............
`
`Premises LAN MAC
`Routines
`
`3813 -
`
`3815 -
`
`Peripheral LAN MAC
`Routines
`
`"'
`"' MAC Routines
`
`Vehicular LAN
`
`3817 -
`
`I'-.
`
`WAN MAC
`Routines
`
`3821 -
`
`-.........
`
`PHY Layer
`Control
`
`Figure42
`
`0052
`
`

`
`3909
`
`Establish
`Participation
`
`~ • rJJ
`•
`""C
`
`~ [
`
`\C
`
`w
`.. .-
`~ ....
`
`•
`
`if necessary,
`PI establish Sleep
`Mode
`
`~ f\)
`f\) ....
`
`f.A
`t-)
`
`s,
`
`f.A
`~
`
`tl1 "' \0
`
`...
`Q\
`\C
`8
`
`3903
`
`3905
`
`If required,
`register Sleep
`Mode With
`OtherLANs
`
`PoiVScan For
`---...ot The Additional
`LAN
`
`3913
`tf necessary,
`reestablish active
`participation
`status
`
`~- -- 1>1
`
`3921
`if necessary,
`reestablish active
`~ · -- ~ participation
`status
`
`3915
`Participate As
`Needed Or Until
`Servicing Other
`LAN Overrides
`
`3923
`
`Explicit Or
`Implicitly Detach
`
`Figure 43
`
`0053
`
`

`
`U.S. Patent
`
`Dec.9, 1997
`
`Sheet 53 of 53
`
`5,696,903
`
`3957
`
`PoiVScan For The
`Master LAN
`
`Continue Master LAN
`Participation Until Need
`For Slave Participation
`Overrides
`
`3961
`
`Establish Slave
`Pa rticipatlon
`
`Establish
`Participation With
`Master
`
`~------~------~~ 3~
`Continue Slave
`ParticipatiOn As Needed
`r Until Need To Service
`Master Overrides
`
`3969
`
`if necessary,
`Register Sleep
`Mode With Slave
`LAN
`
`Detach From Slave
`LAN
`
`Figure 44
`
`0054
`
`

`
`5,696,903
`
`1
`HIERARCWCAL COMMUNICATIONS
`SYSTEM USING MICROLINK. DATA RATE
`SWITCHING, FREQUENCY BOPPING AND
`VEHICULAR LOCAL AREA NETWORKING
`CROSS REFERENCE TO RELATED
`APPUCATIONS (Claiming Benefit Under 35
`u.s.c. 120)
`This application is a continuation-in-part of U.S. appli(cid:173)
`cation Ser. No. 0811 Q7 .386 filed Feb. 16. 1994. abandoned.
`by R. Mahany (Attorney Docket No. DN 37998F) which is
`in turn a continuation-in-part of U.S. application Ser. No.
`081168.478 filed Dec. 16. 1993. abandoned by R. Mahany
`(Attorney Docket No. DN 37998E) whicll is in turn a
`continuation-in-part of U.S. application Ser. No. 081147,377
`filed Nov. 3. 1993. abandoned. by R. Mahany (Attorney
`Docket No. DN 37998D) which is in turn a continuation(cid:173)
`in-part of U.S. application Sec. No. 081101.254 filed Aug. 3.
`1993. abandoned. by R. Mahany (Attorney Docket No. DN
`37998C) which is in tucn a continuation-in-part of U.S.
`application Ser. No. 08/085.662 filed Jun. 29. 1993.
`abandoned. by R. Mahany (Attorney Docket No. DN
`37998B) which is in tucn a continuation-in-part of U.S.
`application Ser. No. 08/076340 filed Jun. 11, 1993.
`abandoned. by R. Mahany (Attorney Docket No. DN
`37998A) which is in turn a continuation-in-part of U.S.
`application Ser. No. 081062.457 filed May 11. 1993.
`abandoned. by R. Mahany (Attorney Docket No. DN
`37998).
`
`AUfHORIZATION PURSUANT TO 37 CFR 1.71
`(d) (e)
`A portion of the disclosure of this patent document
`contains material which is subject to copyright protection.
`The copyright owner has no objection to the facsimile
`reproduction by anyone of the patent document or the patent
`disclosl.U'e. as it appears in the Patent and Trademark Office
`patent file or records. but otherwise reserves all copyright
`rights whatsoevec.
`
`EARUER APPLICATIONS AND PCf
`PUBLICATIONS
`PCT application Ser. No. PCr/U.S.92/08610 Ftled Oct. 1,
`1992. as published under International Publication No. WO
`93/07691 on Apr. 15. 1993.
`
`INCORPORATION BY REFFRENCE
`The above referred to co-pending and earlier applications
`and PCf application Ser. No. PCf/U.S.92/08610 filed Oct.
`1. 1992. as published under International Publication No.
`WO 93/07691 on Apr. 15. 1993. together with U.S. Pat. No.
`5.070.536. by Mahany et al.. U.S. Pat No. 4.924.426. by
`Sojka. and U.S. Pat No. 4.910.794. by Mahany, are incor(cid:173)
`porated herein by reference in their entirety. including
`drawings and appendices. and hereby are made a part of this
`application.
`
`TECHNICAL FIB1.D
`The present invention relates generally to local area
`networks used for transmitting and receiving infcnnation
`and more particularly to an improved method of hierarchical
`communications and to a singular radio using multiple
`communication protocols for servicing cmesponding mul(cid:173)
`tiple radio local area networks.
`
`BACKGROUND OF THE INVENTION
`Single lransmitterradio base station hierarcllical networks
`are known and have certain inherent limitations. The use of
`
`25
`
`15
`
`2
`a single transmitter often results in "dead zones." wherein
`portable or mobile devices are unable to oommunicate with
`the base station. Dead zones may occur when portable or
`mobile devices roam into coverage areas which are blocked
`5 from the base station by physical objects. such as an inner
`wall. for example. or which result from multipath interfer(cid:173)
`ence.
`Dead zones may also occur when a portable or mobile
`device simply roams outside of the physical ooverage area of
`10 the base station. FCC limitations on transmission power
`prevent a network user from increasing the base station
`transmitter power to overcome the communication problems
`associated with dead zones.
`Multiple radio base station networks have been developed
`to overcome a variety of problems with single radio base
`station networks such as spanning physical radio wave
`penetration barriers. wasted transmission power by portable
`computing devices. etc. However. multiple radio base sta(cid:173)
`tion networks have their own inherent problems. For
`example. in a multiple base station network employing a
`20 single shared channel. each base station transmission is
`prone to collision with neighboring base station transmis(cid:173)
`sions in the overlapping coverage areas between the base
`stations. Therefore. it often proves undesirable for each base
`station to use a single or common communication channel
`In contradistinction. to facilitate the roaming of portable
`or mobile devices from one coverage area to another. use of
`a common communication channel for all of the base
`stations is convenient A roaming device may easily move
`between coverage areas without loss of connectivity to the
`30 network.
`Such exemplary competing commonality factors have
`resulted in tradeoff decisions in network design. These
`factors become even more significant when implementing a
`frequency hopping spread spectrum netwo.rk. Frequency
`35 hopping is a desirable transmission technique because of its
`ability to combat frequency selective fading. avoid narrow(cid:173)
`band interference. and provide multiple communications
`channels.
`Again however. changing operating parameters between
`4Q coverage areas aeates difficulties for the roaming devices
`which move therebetween. In particular. when different
`communication parameters are used. a portable or mobile
`device roaming into a new base station ooverage area is not
`able to communicate with the new base station without
`45 obtaining a.nd synchronizing to the new parameters. This
`causes oommunication backlog in the network.
`Moreover. even when a radio frequency network is estab(cid:173)
`lished to cover the premises of a building or group of
`buildings. certain types of oommunication ftow between
`so certain types of devices make for inefiicient use of such a
`netw<llk. In fact. an ordinarily efficient network configura(cid:173)
`tion may be deemed intolerable in certain oommunication
`scenarios.
`Computer terminals and peripheral devices are widely
`55 used. Many types of computer terminals exist which vary
`greatly in tenus of function. power and speed. Many di1fer(cid:173)
`ent ~ oC peripheral devices also exist. such as printers.
`modems. graphics scanners. text scanners. code readers.
`magnetic card readers. external monitors, voice command
`60 interfaces, external storage devices. and so on.
`Computer terminals have bec<lme dramatically smaller
`and more portable, as. for example. lap top computers and
`notebook computers. Computec terminals exist which are
`small enough to be mounted in a vehicle such as a delivery
`65 truck or on a fork lift. Hand held computer terminals exist
`whicll a user can carry in one hand and operate with the
`other.
`
`0055
`
`

`
`5,696,903
`
`3
`4
`communication. The LAN's to date. however. have been
`Typical computer tenn.ioals must physically interface
`designed for large scale wireless communications between
`with peripheral devices. Thus. there must eitha be a cable
`running from the computer tenninal to each periphc:cal
`several portable computer terminals and a host computer.
`device. or the computer terminal must be docked with the
`Therein. the host computer. itself generally a stationary
`5 device, manages a series of stationary peripherals that. upon
`device while information transfec takes place.
`In an office or work place setting. the physical connection
`requests to the host. may be utilized by the portable tmni-
`nals. Otha large scale wireless communications have also
`is typically dooe with cables. These cables pose sevc:cal
`problems. For example. many cables are required in order
`been developed which provide for RF communication
`between several computer tecminals and peripheral devices.
`for a computec terminal to accommodate many periphecal
`devices. In addition, placement of pecipheral devices is 10 but have proven to be ineffective as an ovecall solution. For
`limited by cable lengths. While longer cables may be used,
`example, these systems require the peripheral devices to
`they are costly. Additionally. there may be a limited number
`remain active at all times to listen for an occasional com-
`of ports on a computer terminal. thus limiting the number of
`munication. Although this requirement may be acceptable
`peripherals that may be attached.
`Anothcz- problem arises when several computer terminals
`for stationary peripheral devices receiving virtually unl