United States Patent 15)
`Boggs etal.
`
`[11]
`[45]
`
`4,099,024
`Jul. 4, 1978
`
`[54] COMMUNICATIONS NETWORK
`REPEATER
`
`[75]
`
`Inventors: David R. Boggs, Los Altos Hills;
`Robert M. Metcalfe, Palo Alto, both
`of Calif.
`
`[73] Assignee: Xerox Corporation, Stamford, Conn.
`[21] Appl. No.: 769,141
`[22] Filed:
`Feb. 16, 1977
`[S21]
`Int, Ch? oo. ccsccccesesessssscsesesseesessessesaees HO4L 25/40
`
`
`[52] wk
`[58] Field of Search... 178/71 R, 70 R, 73,
`178/58 R, 58 A; 340/346
`References Cited
`U.S. PATENT DOCUMENTS
`
`[56]
`
`network which includes a plurality of transceivers, the
`repeater being bidirectional and allowing the intercon-
`nection of two segmentsof the network andalso allow-
`ing longer communications networks to be used by
`matching or amplifying the signal level of an incoming
`information packet on one segment and coupling the
`matched or amplified signal to a succeeding segment.
`The repeater has two ports that preferably utilize two
`semiconductor chips, each port having a carrier one-
`shot which detects the presence of an information
`packet arriving at that port. If an incoming port’s one-
`shotis triggered by an incoming packet of information,
`the carrier one-shot for the repeating port and the in-
`coming port transmitter are disabled. If the transceiver
`coupled to the repeating port detects a collision, this
`information is fed back to the incoming port which
`enables the incoming port transmitter thereby causing a
`ow 178/71 R
`
`collision on the incoming network segment which
`causes the termination of the transmission of the data
`packetby a using device already transmitting.
`
`3,673,326—6/1972 Lee sescssssssesserersesenneesneennees
`
`Primary Examiner—Thomas A. Robinson
`Attorney, Agent, or Firm—Irving Keschner; Barry Paul
`Smith
`
`ABSTRACT
`[57]
`A repeater is provided for use in a communications
`
`4 Claims, 2 Drawing Figures
`
`
`
`
`
`
`TERMINATOR |rele,
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`St—seel
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`remoRMINATOR
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`INTERFACE
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`vt
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`
`
`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 1
`
`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 1
`
`

`

`U.S. Patent
`
`July 4,1978
`
`Sheet 1 of 2
`
`4,099,024
`
` TERMINATOR
`
`TRANSCEIVER
`
`
`
` FIG. 7
`
`
`INTERFACE
`
`USING
`DEVICE
`
`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 2
`
`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 2
`
`

`

`U.S. Patent
`
`July 4, 1978
`
`Sheet 2 of 2
`
`4,099,024
`
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`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 3
`
`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 3
`
`

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`1
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`4,099,024
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`tor chips, each port having a “carrier” one-shot which
`detects the presence of a packetat that port. If an in-
`coming port’s one-shot
`is triggered by an incoming
`packet of information, the carrier one-shot for the re-
`peating port and the incoming port transmitter are dis-
`abled. If the transceiver coupled to the repeating port
`detects a collision, this information is fed back to the
`incoming port which enables the incoming port trans-
`mitter causing a collision on the incoming segment and
`causing the termination of the transmission of the data
`packetby a using device already transmitting.
`It is an object of the present invention to provide a
`repeater for use in a communications network.
`It is a further object of the present invention to pro-
`vide a bidirectional repeater for use in a communica-
`tions network.
`It is still a further object of the present invention to
`provide a bidirectional repeater for use in a communica-
`tions network wherein the repeater determines the di-
`rection of flow of data without the use of external con-
`trol.
`It is a further object of the present invention to pro-
`vide a bidirectional repeater for use in a multiaccess
`communications system without central control.
`It is a further object of the present invention to pro-
`vide a bidirectional repeater which, upon detecting a
`collision at the repeating port, passes the collision back
`onto the incoming port segmentof the network causing
`the termination of the transmission of the packet by a
`using device already transmitting.
`BRIEF DESCRIPTION OF THE DRAWINGS
`FIG. 1 showsa portion of the system disclosed in the
`above-identified copending application which requires
`the use of a repeater; and
`FIG. 2 shows schematically the repeater logic of the
`present invention.
`
`COMMUNICATIONS NETWORK REPEATER
`BACKGROUND OF THE INVENTION
`A multiaccess communication system without a cen-
`tral control device(i.e. distributed control) is disclosed
`in copending application Ser. No. 563,741, filed Mar.
`31, 1975 and assigned to the assignee of the present
`invention. The system includes a plurality of transceiv-
`ers connected to the communicating medium utilized in
`the system, each transceiver including transmitting ap-
`paratus for transmitting a signal onto the medium and
`receiving apparatus for receiving a signal onto the me-
`dium and receiving apparatus for receiving a signal
`communicated on the medium by another transceiver.
`Eachtransceiverincludesa collision detector for gener-
`ating a collision signal whenevera signal communicated
`in the medium from anothertransceiver is received
`during the time the transceiveris transmitting a signal
`onto the medium,the collision signal causing theinter-
`ruption ofthe transmission ofa signal onto the medium
`by the using device connected to the transceiver.
`The network comprises sections of a coaxial cable
`suchas disclosed in the copending application or could
`be any suitable medium suchas fiber optic cable, radio
`channel or coaxial cable, etc. Since any medium in-
`cludes losses, and since segments thereof may extend
`over large geographic ranges, various losses occur, and
`for that reason sections of the network are tied across
`repeaters.
`Referenceto repeaters in the aforementioned applica-
`tion was made for purposes of completing the embodi-
`mentsince they are not necessary to practice the inven-
`tion disclosed therein where short communication links
`are contemplated andline losses are taken out byselec-
`tive design of the medium and thetransceiver. How-
`ever,in specific applications wherein large communica-
`tion links are contenplated and selective design of the
`medium and transceiver cannot compensate for line
`losses, repeaters generally are required.
`Since the system described in the aforementioned
`copending application is bidirectional
`in nature ie.,
`there being packets of information flowing in both di-
`rections on the cable which mayarrive at the trans-
`ceiverof a using devicefrom eitherdirection,a repeater
`for use in such system must be capable of bidirectional
`operationi.e., the repeater preferably will determinein
`whichdirection to repeat the information packet with-
`out external control. Further, the repeater, which has
`an incoming and repeating port, should be capable of
`responding to the detection of a collision by a trans-
`ceiver at the repeating port and pass the occurrence of
`the collision back onto the incoming segment via the
`incoming port transceiver transmitter and cause the
`using device already transmitting the data packet to
`cease transmission.
`
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`SUMMARYOF THE PRESENT INVENTION
`The present invention provides a bidirectional re-
`peater for use in a communicating network or medium
`which includesa plurality of transceivers, the repeater
`being bidirectional and allowingthe interconnection of
`two segments of the network and also allowing longer
`communicating networks to be used by matching or
`amplifying the signal level of an incoming information
`packet on one segment and coupling the matched or
`amplified signal to a succeeding segment. The repeater
`has two ports that preferably utilize two semi-conduc-
`
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`65
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`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`Since the present invention is directed to a repeater
`which is particularly adapted for use in a multi-access
`communications system without central control as de-
`scribed in copendingapplication Ser. No, 563,741,filed
`Mar. 31, 1975, the repeater will be described in the
`environmentdisclosed, including terminology and defi-
`nitionsutilized therein,in the copendingapplication and
`the teachings therein necessary for an understanding of
`the present invention are incorporated herein by refer-
`ence.
`
`As shown in FIG. 1, proximate the intersection of
`cables 10 and 20 (communication medium) there is a
`repeater circuit generally designated by the numeral 50
`communicating on one side between a tap 103 on cable
`10 and a tap 203 on cable 20. On theinterior of the
`repeater 50, the cable 10 via tap 103 is tied to a trans-
`ceiver 243, across a repeaterlogic section 60 to a trans-
`ceiver 245 which then connectsto cable 20 by way ofa
`tap 203. In this manner, an extended networkis formed
`in which two network segments, or cables 10 and 20,
`are tied together across repeater 50 which matches up
`the signals between the cables. It should be noted thatin
`addition to matching signals between cables,
`the re-
`peater logic 60 may include amplifying means if the
`selected interconnection points on cables 10 and 20 are
`sufficiently far from the sourceof a data packet so that
`the data packet input to the transceiver has lost suffi-
`cient strength to require amplification. For the repeater
`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 4
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`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 4
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`logic described hereinafter with reference to FIG. 2,it
`connectors 300 and 302 (or incoming and repeater
`will be assumed that the transceivers 245 and 243 ac-
`ports, respectively, in the left to right mode of opera-
`complish the amplification.
`tion) are coupled to respective transceivers (not shown)
`The specific description of the transceivers 243 and
`243 and 245 of the type described in the aforementioned
`245 are set forth in the copending application. For pur-
`copending patent application. One-shot multivibrators
`poses of this disclosure it is sufficient to note that the
`320 and 360 maybe referred to as “carrier detectors”
`transceiver is capable of receiving an inputsignal, (data
`(an analogy to radio communications) since they moni-
`packet), amplifying it if necessary, transmitting an out-
`tor or detect incoming data packets coupled to their
`put signal (data packet) and generatinga signal indicat-
`respective connectors 300 and 302 by transceivers 243
`ing that a data collision (data packets from twodifferent
`and 245, respectively.
`sources are being transmitted and received substantially
`In operation, it is assumed that a data packetis being
`simultaneously by the transceiver) has occurred.
`repeated from cable 10 via transceiver 243 to repeater
`Referring now to FIG. 2, elements 300 and 302 are
`60 and hence to cable 20 via transceiver 245. If repeater
`schematic representations of the connections between
`60 is going to repeat a signal from cable 10 to cable 20,
`transceivers 243 and 245 respectively, and repeater
`a data packetis received at data port 304 of incoming
`logic 60 and will be referred to hereinafter as the incom-
`port 300 from transceiver 243 and applied to one input
`ing and repeating ports, respectively,for transmission of
`of carrier detector 320 and one input of NAND gate 338
`data packets from left to right as viewed from the fig-
`via lead 340, the output of NANDgate 338 being cou-
`ure. Obviously,if transmission wasin the reverse direc-
`pled to transmit data port 312 of repeating port 302 and
`tion, element 300 would act as the repeating port and
`then to transceiver 245. Similarly, if a data packetis to
`element 302 the incoming port. Incoming port 300 in-
`be repeated from cable 20 to cable 10, the signal would
`cludes input data port 304, transmit data port 306 and
`be received by transceiver 245 and applied to one input
`collision signal port 308, while repeater port 302 in-
`ofcarrier detector 360 and via NANDgate 334 to trans-
`cludes input data port 310, transmit data port 312 and
`mit data port 306 and thence to transceiver 243. Since
`collision signal port 314. Input data port 304 is con-
`both halves of the repeater shown operate essentially
`nected to the “A” input of one-shot multivibrator 320
`the same, only the transmission of a data packet from
`which may comprise Texas Instruments device SN
`transceiver 243 to transceiver 245 will be described in
`74123. The capacitor 321, resistor 323 and potential
`detail. The leading bit of a packet (and subsequent bit-
`source Vcc shown are utilized to determine the time
`transitions within the packet) causes the Q output of
`duration of the active state of the one-shot multivibrator
`carrier detector 320 to go true(logic “1”) and disables
`320 and should be set to about 3 ofthe bit times of the
`carrier detector 360 holding its Q output true. That Q
`incoming data if the incoming data is phase encoded as
`output ofcarrier detector 360 is applied to one input of
`set forth in the copending patent application. The Q
`NANDgate 338 which allows the data packet applied
`output of multivibrator 320 is coupled to one input of
`to port 304 to be repeated at port 312 (transmit data
`NANDgate 326and to the inverting or “B”input of
`one-shot 360 via leads 330 and 332, respectively. The
`ports use “0” logic to enable the transmit inputs oftheir
`associated transceivers). Note that carrier detector 360
`inverted or Q output of one-shot 320 is coupled to one
`input of NANDgate 334 via lead 336. The input data
`must be disabled to preventit from being triggered by
`the incoming data from transceiver 245 which will be a
`packet received at input data port 304 is also applied to
`one input of NANDgate 338 via lead 340. The output
`copy ofthe data being transmitted to that transceiver, a
`characteristic of the particular transceiver design set
`of NAND gates 326 and 334 are wired “ORed”to-
`getherat point 342 and coupledto the transmit data port
`forth in the aforementioned copending patent applica-
`tion. The Q outputof carrier detector 320 will be false
`306. A collision signal applied to the port 308 by trans-
`(logic “O”) and is applied to the input of NAND gate
`ceiver 243 is coupled via lead 344 to one input of
`NANDgate 346.
`334 via lead 336 to disable the transmit data port 306.
`Referring to the symmetrical right hand portion of
`This is necessary because as mentioned above, trans-
`the schematic diagram, input data received at the input
`ceiver 245 will be supplying as input data at port 310, a
`data port 310 is coupled to the “A” input of one-shot
`copy of the data packet being transmitted at transmit
`360 via lead 350, the received data packet also being
`port 312.
`coupled to the other input of NANDgate 334 via lead
`If the data packet applied to transmit data port 312is
`352. One-shot multivibrator 360 is identical in configu-
`transmitted substantially simultaneously with a data
`ration and operation to one-shot multivibrator 320. The
`packet from some other using device on cable 20, a
`one-shot multivibrators 320 and 360 may comprise
`collision is detected by transceiver 245 andacollision
`chips made by Texas Instruments Corporation (TIC)
`signal is applied to port 314 and thence to NANDgate
`Model No. 74123 asset forth hereinabove and NAND
`326 via lead 368. It should be noted that the outputs of
`gates 334, 326, 338 and 346 may comprise TIC chips
`NANDgates 326 and 334 are joined at point 342 in a
`7438. The Q output of one-shot 360 is coupled to one
`“wired” OR configuration. Since a logic “1”input is
`input of NANDgate 346 via lead 364 and the Q output
`now applied to gate 326 via lead 368 along with the
`of one-shot 360 is coupled to the other input of NAND
`logic “1” input on lead 330, NAND gate 326 applies a
`gate 338 via lead 364. The output of NANDgates 338
`“O” logic signal to transmit data port 306 via wired OR
`and 346 are wired “ORed” together at point 366 and
`342, causing a signal to exist on the transmitter line of
`coupled to the transmit data port 312. The output from
`transceiver 243. A signal
`is therefore transmitted to
`collision signal port 308 is applied to the other input of
`network segment 10 connected to transceiver 243 caus-
`NANDgate 346 via lead 344, the collision signal input
`ing a deliberate collision to be created with the using
`applied to port 314 by transceiver 245 being applied to
`device already transmitting on segment 10 and causing
`the other input of NAND gate 326 via lead 368. The Q
`that using device to terminate its transmission (see the
`output of one-shot 360 is coupled to the other or “B”
`description of the transceiver operation in the afore-
`input of one-shot 320 via lead 370. As indicated, the
`mentioned copending patent application).
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`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 5
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`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 5
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`

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`4,099,024
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`20
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`The bidirectional feature of repeater 60 is clearly
`the time the transceiver is transmitting data onto the
`observed from the operation thereof as described here-
`medium, said repeater comprising:
`inabove.If a data packet isfirst received at input data
`a first port connected toafirst one ofsaid transceiv-
`port 304, the data packet is repeated at port 312 (i.e.
`ers for receiving data communicated on the me-
`dium and received bysaid first transceiver;
`from left to right as viewed from the drawing). If a data
`a second port connectedto said first transceiver for
`packetis first received at input data port 310, the data
`receiving collision signals generated by said first
`packetis repeated at port 306 (right to left as viewed
`transceiver;
`from the drawing). If a data collision is detected at
`a third port connected to a second oneofsaid trans-
`repeating port 314 the transmit data port 306 at incom-
`ceivers for applying data andcollision signals to
`ing port 300 causes the transceiver coupled thereto to
`said second transceiver for transmission thereby
`create a collision on the connected network whereby
`onto the medium;
`the using device already transmitting on the network
`first means for coupling data from said first port to
`terminates transmission. It should be noted that the
`said third port; and
`transceiveritself does not cease the transmission whenit
`second meansfor coupling collision signals from said
`detectsa collision, rather, the collision signal causes the
`second port to said third port.
`2. The repeaterof claim 1, further comprising:
`using device connectedto the transceiverto stop send-
`a fourth port connected to said secondtransceiver for
`ing bits to the transceiver.
`receiving data communicated on the medium and
`While the invention has been described with refer-
`received by said second transceiver;
`ence toits preferred embodiment,it will be understood
`a fifth port connected to said second transceiver for
`by those skilled in the art that various changes may be
`receiving collision signals generated by said second
`made and equivalents may be substituted for elements
`transceiver;
`thereof not departing from the true spirit and scope of
`a sixth port connected to said first transceiver for
`the invention. In addition, many modifications may be
`applying data and collision signals to said first
`made to adapta particular situation or material to the
`transceiver for transmission thereby onto the me-
`teaching of the invention without departing from its
`dium;
`third meansfor coupling data from said fourth port to
`essential teachings.
`Whatis claimedis:
`said sixth port; and
`fourth means for coupling collision signals from said
`1. A repeater for use in a data communication system
`fifth port to said sixth port.
`of the type comprising a communicating medium, a
`3. The repeater of claim 2, further comprising means
`plurality of transceivers connected to the medium, each
`for disabling said third means in responseto receipt of
`transceiver capable of transmitting data onto the me-
`data atsaid first port.
`dium, receiving data communicated on the medium by
`4. The repeater ofclaim 3, further comprising means
`another transceiver, and generating a collision signal
`for disabling said first means in response to receipt of
`whenever data communicated on the medium by an-
`data at said fourth port.**« *&
`*&
`#
`other transceiver is received by the transceiver during
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`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 6
`
`PMC Exhibit 2086
`Apple v. PMC
`IPR2016-00753
`Page 6
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`