(12) United States Patent
`Bremer
`
`111111
`
`1111111111111111111111111111111111111111111111111111111111111
`US006614838Bl
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 6,614,838 Bl
`Sep.2,2003
`
`(54) SYSTEM AND METHOD OF
`COMMUNICATION VIA EMBEDDED
`MODULATION
`
`Primary Examiner---Phuong Phu
`(74) Attorney, Agent,
`or Firm-Thomas, Kayden,
`Horstemeyer & Risley LLP
`
`(75)
`
`Inventor: Gordon Bremer, Clearwater, FL (US)
`
`(57)
`
`ABSTRACT
`
`(73)
`
`Assignee: Paradyne Corporation, Largo, FL
`(US)
`
`( *)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21) Appl. No.: 09/205,205
`
`(22) Filed:
`
`Dec. 4, 1998
`
`Related U.S. Application Data
`(60) Provisional application No. 60/067,562, filed on Dec. 5,
`1997.
`
`Int. Cl? .............................. H04B l/38; H04L 5/16
`(51)
`(52) U.S. Cl. ....................... 375/220; 375/222; 375/219;
`370/453
`(58) Field of Search ................................. 375/261, 222,
`375/219, 220; 370/328, 338, 389, 449,
`452, 453, 457
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`5,563,883 A * 10/1996 Cheng
`5,936,949 A * 8/1999 Pasternak et a!.
`5,999,563 A * 12/1999 Polley eta!.
`6,021,158 A * 2/2000 Schurr et a!. ............... 375/211
`6,067,297 A * 5!2000 Beach
`* cited by examiner
`
`A communication system includes a master transceiver in
`communication with one or more transceivers, for example,
`a first tributary transceiver and a second tributary transceiver
`over a communication medium. The first tributary trans(cid:173)
`ceiver uses a primary modulation method for communica(cid:173)
`tion while the second tributary transceiver uses a secondary
`or embedded modulation method for communication. The
`master transceiver and tributary transceivers each include a
`processor, memory, and control logic for controlling their
`operation. While the primary modulation method is nor(cid:173)
`mally used for transmissions on the communication
`medium, the master transceiver can communicate with the
`second tributary transceiver by notifying the first tributary
`transceiver that the primary modulation method is being
`temporarily replaced by the secondary or embedded modu(cid:173)
`lation method. The master transceiver can then exchange
`information with the second tributary transceiver while the
`first tributary transceiver ignores any secondary modulation
`transmissions. In the meantime, the first tributary transceiver
`conditions itself to look for a trailing sequence from the
`master transceiver indicating that communication with the
`second tributary transceiver is complete. When the master
`transceiver transmits the trailing sequence using the primary
`modulation method, the first tributary transceiver conditions
`itself to look for primary modulation transmissions while the
`second tributary transceiver conditions itself to ignore pri(cid:173)
`mary modulation transmissions.
`
`18 Claims, 7 Drawing Sheets
`
`Master Transceiver
`Type A+ B
`64
`
`rl Modulator
`
`74 r Demodulator 1-
`
`72 1---
`
`Memory
`76
`
`-
`
`Control
`Program
`Type A+ B
`78
`
`Trib Modem
`Type X
`66
`
`Memory
`88
`
`-
`
`Control
`Program
`Type X
`92
`
`Central Procesing
`Unit (CPU)
`I~
`68
`
`94
`
`9
`
`~ ~
`
`rl Modulator
`
`84
`
`86 r Demodulator ~
`
`f--
`
`+------->
`
`Central Procesing
`Unit (CPU)
`82
`
`Exhibit 1214 01/14
`
`

`

`U.S. Patent
`
`Sep.2,2003
`
`Sheet 1 of 7
`
`US 6,614,838 Bl
`
`22
`~
`
`Tributary
`Transceiver
`26
`
`Tributary
`Transceiver
`26
`
`Master
`Transceiver
`24
`
`~--~------------~-----··
`
`~----~------~-----------··
`28
`
`Tributary
`Transceiver
`26
`
`FIG. 1
`Prior Art
`
`Exhibit 1214 02/14
`
`

`

`U.S. Patent
`
`Sep.2,2003
`
`Sheet 2 of 7
`
`US 6,614,838 Bl
`
`Trib 2
`26b
`
`Master
`24
`
`Trib 1
`26a
`
`Establish
`Modulation
`
`Establish
`Modulation
`
`Training
`
`Data
`
`Trailing
`
`Training
`
`Data
`
`Trailing
`
`Training
`
`Data
`
`Trailing
`
`3 2 v
`3 4 v
`l) 6
`3 8 v
`
`4 2 v 4 4 v 4 6 v
`
`4 8 v 5 2
`
`_)
`5 4
`_)
`
`FIG. 2
`Prior Art
`
`3 2
`
`3 4
`
`"---
`"---
`"---
`"---
`
`3 6
`
`3 8
`
`Training
`
`Data
`
`Trailing
`
`.......
`
`4 8
`\__
`5 2
`\__
`5 4
`\__
`
`5 6
`
`"---
`5 8
`\__
`6 2
`\__
`
`Training
`
`Data
`
`Trailing
`
`Training
`
`Data
`
`Trailing
`
`Exhibit 1214 03/14
`
`

`

`U.S. Patent
`
`Sep.2,2003
`
`Sheet 3 of 7
`
`US 6,614,838 Bl
`
`Master Transceiver
`Type A+ B
`64
`
`Modulator
`72
`
`Memory
`76
`
`Control
`Program
`Type A+ B
`78
`
`Demodulator
`~ 74
`
`~---,
`
`r r
`
`Central Procesing
`Unit (CPU)
`68
`
`94
`
`94
`
`\__ L/
`
`Trib Modem
`Type X
`66
`-
`
`Memory
`88
`-
`
`Control
`Program
`Type X
`92
`
`-
`
`~
`
`Modulator
`84
`
`-
`
`___.
`
`Demodulator
`86
`
`-
`
`u
`
`,
`
`..
`
`Central Procesing
`Unit (CPU)
`82
`
`-
`
`FIG. 3
`
`Exhibit 1214 04/14
`
`

`

`U.S. Patent
`
`Sep.2,2003
`
`Sheet 4 of 7
`
`US 6,614,838 Bl
`
`100
`
`~
`
`Tributary
`Transceiver
`Type A
`66a
`
`Tributary
`Transceiver
`Type A
`66a
`
`Master
`Transceiver
`Type A+ 8
`64
`
`~--~--------------~----·.
`
`~--~~------~----------·.
`94
`
`Tributary
`Transceiver
`Type 8
`66b
`
`FIG. 4
`
`Exhibit 1214 05/14
`
`

`

`U.S. Patent
`
`Sep.2,2003
`
`Sheet 5 of 7
`
`US 6,614,838 Bl
`
`Trib 2
`Type B
`66b
`-
`
`Master
`Type A+ B
`64
`- -
`
`Trib 1
`Type A
`66a
`
`Establish Modulation
`Type A
`
`04
`1
`~
`
`Training - Change
`To Type B
`
`1
`06
`l.--J
`
`Trailing
`Type A
`
`
`1 14
`~
`FIG. 5
`
`10 8
`'-
`
`Address+ Data
`
`11 8
`\..__
`
`Data
`
`Training
`
`Data
`
`Trailing
`
`Training
`
`Data
`
`Trailing
`
`1 26
`~
`1 32
`~
`
`
`1 34
`~
`
`1 38
`l----'
`1 42
`~
`1 44
`__.)
`
`Exhibit 1214 06/14
`
`

`

`U.S. Patent
`
`Sep.2,2003
`
`Sheet 6 of 7
`
`US 6,614,838 Bl
`
`Type 8
`Address+ Data
`
`Ignore
`Type A
`Transmission
`102
`
`Complete
`Transmission
`
`Receive
`Type 8
`Data
`112
`
`Transmit
`Type 8
`Data
`116
`
`Time Out/
`Trailing
`
`Poll Request/
`Trailing
`
`FIG. 6
`
`Exhibit 1214 07/14
`
`

`

`U.S. Patent
`
`Sep.2,2003
`
`Sheet 7 of 7
`
`US 6,614,838 Bl
`
`Ignore
`Type 8
`Transmission
`124
`
`Trailing:
`Type A
`
`Training:
`Change To Type 8
`
`Complete
`Transmission
`
`Transmit
`Type A
`Data
`136
`
`Wait For
`Type A
`Training
`122
`
`Trailing
`
`Poll RequesU
`Trailing
`
`FIG. 7
`
`Training
`
`Receive
`Type A
`Data
`128
`
`Exhibit 1214 08/14
`
`

`

`US 6,614,838 Bl
`
`1
`SYSTEM AND METHOD OF
`COMMUNICATION VIA EMBEDDED
`MODULATION
`
`CROSS REFERENCE TO RELATED
`APPLICATION
`
`This application claims priority to and the benefit of the
`filing date of U.S. Provisional Application No. 60/067,562,
`entitled "Embedded Modulations," filed Dec. 5, 1997, which
`is incorporated by reference as if set forth in full hereinbe(cid:173)
`low.
`
`TECHNICAL FIELD
`
`5
`
`2
`applications (e.g., internet access) require high performance
`modulation, such as quadrature amplitude modulation
`(QAM), carrier amplitude and phase (CAP) modulation, or
`discrete multitone (DMT) modulation, while other applica-
`tions (e.g., power monitoring and control) require only
`modest data rates and therefore a low performance modu(cid:173)
`lation method. All users in the system will generally have to
`be equipped with a high performance modem to ensure
`modulation compatibility. These state of the art modems are
`10 then run at their lowest data rates for those applications that
`require relatively low data throughput performance. The
`replacement of inexpensive modems with much more
`expensive state of the art devices due to modulation com(cid:173)
`patibility imposes a substantial cost that is unnecessary in
`terms of the service and performance to be delivered to the
`end user.
`Accordingly, what is sought, and what is not believed to
`be provided by the prior art, is a system and method of
`communication in which multiple modulation methods are
`20 used to facilitate communication among a plurality of
`modems in a network, which have heretofore been incom(cid:173)
`patible.
`
`The present invention relates generally to the fields of 15
`data communications and modulator/demodulators
`(modems), and, more particularly, to a data communications
`system in which a plurality of modulation methods are used
`to facilitate communication among a plurality of modem
`types.
`
`BACKGROUND OF THE INVENTION
`
`In existing data communications systems, a transmitter
`and receiver modem pair can successfully communicate
`only when the modems are compatible at the physical layer. 25
`That is, the modems must use compatible modulation meth(cid:173)
`ods. This requirement is generally true regardless of the
`network topology. For example, point-to-point, dial-up
`modems operate in either the industry standard V.34 mode or
`the industry standard V.22 mode. Similarly, in a multipoint 30
`architecture, all modems operate, for example, in the indus-
`try standard V.27bis mode. While the modems may be
`capable of using several different modulation methods, a
`single common modulation is negotiated at the beginning of
`a data session to be used throughout the duration of the 35
`session. Should it become necessary to change modulation
`methods, the existing data session is torn down, and a new
`session is negotiated using the new modulation method.
`Clearly, tearing down an existing data session causes a
`significant disruption in communication between the two 40
`modems.
`As discussed in the foregoing, communication between
`modems is generally unsuccessful unless a common modu(cid:173)
`lation method is used. In a point-to-point network 45
`architecture, if a modem attempts to establish a communi(cid:173)
`cation session with an incompatible modem, one or both of
`the modems will make several attempts to establish the
`communication link until giving up after a timeout period
`has expired or the maximum number of retry attempts has 50
`been reached. Essentially, communication on the link is
`impossible without replacing one of the modems such that
`the resulting modem pair uses a common modulation
`method.
`In a multipoint architecture, a single central, or "master,"
`modem communicates with two or more tributary or "trib"
`modems using a single modulation method. If one or more
`of the trib modems are not compatible with the modulation
`method used by the master, those tribs will be unable to
`receive communications from the master. Moreover, 60
`repeated attempts by the master to communicate with the
`incompatible trib(s) will disturb communications with com(cid:173)
`patible trib(s) due to time wasted in making the futile
`communication attempts.
`Thus, communication systems comprised of both high 65
`performance and low or moderate performance applications
`can be very cost inefficient to construct. For example, some
`
`SUMMARY OF THE INVENTION
`The present invention is generally directed to a system
`and method of communication between a master transceiver
`and a plurality of tributary transceivers in a multipoint
`communication system in which the tributary transceivers
`use different types of modulation methods. Broadly stated,
`the communication system includes a master transceiver in
`communication with a first tributary transceiver and a sec(cid:173)
`ond tributary transceiver over a communication medium.
`The first tributary transceiver uses a primary modulation
`method for communication while the second tributary trans(cid:173)
`ceiver uses a secondary or embedded modulation method for
`communication. The master transceiver and tributary trans(cid:173)
`ceivers each include a processor, memory, and control logic
`for controlling their operation. While the primary modula(cid:173)
`tion method is normally used for transmissions on the
`communication medium, the master transceiver can com(cid:173)
`municate with the second tributary transceiver by notifying
`the first tributary transceiver that the primary modulation
`method is being temporarily replaced by the secondary or
`embedded modulation method. The master transceiver can
`then exchange information with the second tributary trans(cid:173)
`ceiver while the first tributary transceiver ignores any sec(cid:173)
`ondary modulation transmissions. In the meantime, the first
`tributary transceiver conditions itself to look for a trailing
`sequence from the master transceiver indicating that com(cid:173)
`munication with the second tributary transceiver is com(cid:173)
`plete. When the master transceiver transmits the trailing
`sequence using the primary modulation method, the first
`tributary transceiver conditions itself to look for primary
`modulation transmissions while the second tributary trans-
`55 ceiver conditions itself to ignore primary modulation trans(cid:173)
`missions.
`The present invention has many advantages, a few of
`which are delineated hereafter as merely examples.
`One advantage of the present invention is that it provides
`to the use of a plurality of modem modulation methods on
`the same communication medium.
`Another advantage of the present invention is that a
`master transceiver can communicate seamlessly with tribu(cid:173)
`tary transceivers or modems using incompatible modulation
`methods.
`Other features and advantages of the present invention
`will become apparent to one with skill in the art upon
`
`Exhibit 1214 09/14
`
`

`

`US 6,614,838 Bl
`
`3
`examination of the following drawings and detailed descrip(cid:173)
`tion. It is intended that all such additional features and
`advantages be included herein within the scope of the
`present invention.
`
`BRIEF DESCRIPTION OF THE SEVERAL
`VIEWS OF THE DRAWINGS
`
`The present invention can be better understood with
`reference to the following drawings. The components and
`representations in the drawings are not necessarily to scale,
`emphasis instead being placed upon clearly illustrating the
`principles of the present invention. Moreover, in the
`drawings, like reference numerals designate corresponding
`parts throughout the several views.
`FIG. 1 is a block diagram of a prior art multipoint
`communication system including a master transceiver and a
`plurality of tributary transceivers;
`FIG. 2 is a ladder diagram illustrating the operation of the
`multipoint communication system of FIG. 1;
`FIG. 3 is a block diagram of a master transceiver and
`tributary transceiver for use in the multipoint communica(cid:173)
`tion system ofFIG.1 in accordance with the principles of the
`present invention;
`FIG. 4 is a block diagram of a multipoint communication
`system including the master transceiver and a plurality of
`tributary transceivers of the type illustrated in FIG. 3;
`FIG. 5 is a ladder diagram illustrating the operation of the
`multipoint communication system of FIG. 4;
`FIG. 6 is a state diagram for a tributary transceiver of
`FIGS. 3-5 using a secondary modulation method in accor(cid:173)
`dance with the principles of the present invention; and
`FIG. 7 is a state diagram for a tributary transceiver of
`FIGS. 3-5 using a primary modulation method in accor- 35
`dance with the principles of the present invention.
`
`4
`performance and/or to select optional features, and 6) to
`confirm agreement with regard to the foregoing purposes
`prior to entering into data communication mode between the
`users. In a multipoint system, the address of the trib with
`5 which the master is establishing communication is also
`transmitted during the training interval. At the end of a data
`session a communicating pair of modems will typically
`exchange a sequence of signals known as trailing signals for
`the purpose of reliably stopping the session and confirming
`10 that the session has been stopped. In a multipoint system,
`failure to detect the end of a session will delay or disrupt a
`subsequent session.
`Referring now to FIG. 2, an exemplary multipoint com(cid:173)
`munication session is illustrated through use of a ladder
`15 diagram. This system uses polled multipoint communication
`protocol. That is, a master controls the initiation of its own
`transmission to the tribs and permits transmission from a trib
`only when that trib has been selected. At the beginning of the
`session, the master transceiver 24 establishes a common
`20 modulation as indicated by sequence 32 that is used by both
`the master 24 and the tribs 26a, 26b for communication.
`Once the modulation scheme is established among the
`modems in the multipoint system, The master transceiver 24
`transmits a training sequence 34 that includes the address of
`25 the trib that the master seeks to communicate with. In this
`case, the training sequence 34 includes the address of trib
`26a. As a result, trib 26b ignores training sequence 34. After
`completion of the training sequence 34, master transceiver
`24 transmits data 36 to trib 26a followed by trailing
`30 sequence 38, which signifies the end of the communication
`session. Note that trib 26b ignores data 36 and trailing
`sequence 38 as it was not requested for communication
`during training sequence 34.
`At the end of trailing sequence 38, trib 26a transmits
`training sequence 42 to initiate a communication session
`with master transceiver 24. Because master transceiver 24
`selected trib 26a for communication as part of training
`sequence 34, trib 26a is the only modem that will return a
`transmission. Thus, trib 26a transmits data 44 destined for
`40 master transceiver 24 followed by trailing sequence 46 to
`terminate the communication session.
`The foregoing procedure is repeated except master trans(cid:173)
`ceiver identifies trib 26b in training sequence 48. In this
`case, trib 26a ignores the training sequence 48 and the
`subsequent transmission of data 52 and trailing sequence 54
`because it does not recognize its address in training
`sequence 48. Master transceiver 24 transmits data 52 to trib
`26b followed by trailing sequence 54 to terminate the
`communication session. To send information back to master
`transceiver 24, trib 26b transmits training sequence 56 to
`establish a communication session. Master transceiver 24 is
`conditioned to expect data only from trib 26b because trib
`26b was selected as part of training sequence 48. Trib 26b
`55 transmits data 58 to master transceiver 24 terminated by
`trailing sequence 62.
`The foregoing discussion is based on a two-wire, half(cid:173)
`duplex multipoint system. Nevertheless, it should be under(cid:173)
`stood that the concept is equally applicable to four-wire
`60 systems.
`Consider the circumstance in which master transceiver 24
`and trib 26b share a common modulation type A while trib
`26a uses a second modulation type B. When master trans(cid:173)
`ceiver attempts to establish A as a common modulation
`during sequence 32, trib 26a will not be able to understand
`that communication. Moreover, trib 26a will not recognize
`its own address during training interval34 and will therefore
`
`DETAILED DESCRIPTION OF THE
`INVENTION
`
`While the invention is susceptible to various modifica(cid:173)
`tions and alternative forms, a specific embodiment thereof is
`shown by way of example in the drawings and will herein be
`described in detail. It should be understood, however, that
`there is no intent to limit the invention to the particular form
`disclosed, but on the contrary, the invention is to cover all 45
`modifications, equivalents, and alternatives falling within
`the spirit and scope of the invention as defmed by the claims.
`With reference to FIG. 1, a prior art multipoint commu(cid:173)
`nication system 22 is shown to comprise a master modem or
`transceiver 24, which communicates with a plurality of 50
`tributary modems (tribs) or transceivers 26-26 over com(cid:173)
`munication medium 28. Note that all tribs 26-26 are
`identical in that they share a common modulation method
`with the master transceiver 24. Thus, before any communi(cid:173)
`cation can begin in multipoint system 22, the master trans(cid:173)
`ceiver and the tribs 26-26 must agree on a common
`modulation method. If a common modulation method is
`found, the master transceiver 24 and a single trib 26 will then
`exchange sequences of signals that are particular subsets of
`all signals that can be communicated via the agreed upon
`common modulation method. These sequences are com(cid:173)
`monly referred to as training signals and can be used for the
`following purposes: 1) to confirm that the common modu(cid:173)
`lation method is available, 2) to establish received signal
`level compensation, 3) to establish time recovery and/or 65
`carrier recovery, 4) to permit channel equalization and/or
`echo cancellation, 5) to exchange parameters for optimizing
`
`Exhibit 1214 10/14
`
`

`

`US 6,614,838 Bl
`
`5
`ignore data 36 and trailing sequence 38. Master transceiver
`24 may time out waiting for a response from trib 26a
`because trib 26a will never transmit training sequence 42,
`data 44, and trailing sequence 46 due to the failure of trib
`26a to recognize the communication request (training
`sequence 34) from master transceiver 24. Thus, if the tribs
`in a multipoint communication system use a plurality of
`modulation methods, the overall communication efficiency
`will be disrupted as specific tribs will be unable to decipher
`certain transmissions from the master transceiver and any
`unilateral transmission by a trib that has not been addressed
`by the master transceiver will violate the multipoint proto(cid:173)
`col.
`As discussed hereinbefore, however, it is desirable to
`design a multipoint communication system comprising tribs
`that use a plurality of modulation methods. For example, one
`moderately priced trib may be used to communicate at a
`relatively high data rate for some applications, such as
`Internet access, while another, lower priced, trib is used to
`communicate at a lower data rate for other applications, such
`as power monitoring and control. The needs of these differ(cid:173)
`ent applications cannot be efficiently met by a single modu(cid:173)
`lation. While it is possible to use high performance tribs
`running state of the art modulation methods such as QAM,
`CAP, or DMT to implement both the high and low data rate 25
`applications, significant cost savings can be achieved if
`lower cost tribs using low performance modulation methods
`are used to implement the lower data rate applications.
`A block diagram of a master transceiver 64 in communi(cid:173)
`cation with a trib 66 in accordance with the principles of the
`present invention is shown in FIG. 3. Master transceiver 64
`comprises a central processing unit (CPU) 68 in communi(cid:173)
`cation with modulator 72, demodulator 74, and memory 76.
`Memory 76 holds software control program 78 and any data
`necessary for the operation of master transceiver 64. Control
`program 78 includes logic for implementing a plurality of
`modulation methods. For purposes of illustration, control
`program 78 can implement both a type A and a type B
`modulation through modulator 72 and demodulator 74.
`Trib 66 comprises CPU 82 in communication with modu(cid:173)
`lator 84, demodulator 86, and memory 88. Memory 88,
`likewise holds software control program 92 and any data
`necessary for the operation of trib 66. Control programs 78
`and 92, are executed by CPUs 68 and 82 and provide the
`control logic for the processes to be discussed herein.
`Control program 92 includes logic for implementing a
`particular modulation method, which, for purposes of
`illustration, is called type X. Inasmuch as master transceiver
`64 is capable of running either a type A or a type B 50
`modulation method, type X refers to one of those two
`modulation methods. The master transceiver 64 communi(cid:173)
`cates with trib 66 over communication medium 94.
`Referring now to FIG. 4, a multipoint communication
`system 100 is shown comprising a master transceiver 64
`along with a plurality of tribs 66-66. In this example, two
`tribs 66a-66a run a type A modulation method while one
`trib 66b runs a type B modulation method. The present
`invention permits a secondary or embedded modulation
`method (e.g., type B) to replace the standard modulation 60
`method (e.g., type A) after an initial training sequence. This
`allows the master transceiver 64 to communicate seamlessly
`with tribs of varying types.
`The operation of multipoint communication system 100
`will be described hereafter with reference to the ladder 65
`diagram of FIG. 5 and the state diagrams of FIGS. 6 and 7.
`A communication session between the master transceiver 64
`
`6
`and a type B trib 66b will be discussed first. A state diagram
`for a type B trib 66b is shown in FIG. 6. Type B trib 66b is
`initialized in state 102 in which type A modulation trans(cid:173)
`missions are ignored. In the present example, the primary
`5 modulation method is type A, thus, as shown in FIG. 5,
`master transceiver 64 establishes type A as the primary
`modulation in sequence 104. Note that because trib 66b
`responds only to type B modulation transmissions, only the
`type A tribs 66a-66a are receptive to transmission
`10 sequence 104.
`To switch from type A modulation to type B modulation,
`master transceiver 64 transmits a training sequence 106 to
`type A tribs 66a in which these tribs are notified of an
`impending change to type B modulation. The switch to type
`15 B modulation could be limited according to a specific time
`interval or for the communication of a particular quantity of
`data. After notifying the type A tribs 66a of the change to
`type B modulation, master transceiver 64, using type B
`modulation, transmits data along with an address in
`20 sequence 108, which is destined for a particular type B trib
`66b. The type B trib 66b targeted by the master transceiver
`64 will transition to state 112 as shown in FIG. 6 upon
`detecting its own address where it processes the data trans-
`mitted in sequence 108.
`After completing transmission sequence 108, master
`transceiver 64 transmits a trailing sequence 114 using type
`A modulation thus notifying all type A tribs 66a that type B
`modulation transmission is complete. If master transceiver
`64 has not transmitted a poll request to the type B trib 66b
`30 in sequence 108, then the type B trib 66b that was in
`communication with the master transceiver 64 will return to
`state 102 after timing out based on the particular time
`interval defmed for the type B modulation transmission or
`transfer of the particular quantity of data. Note that the
`35 trailing sequence 114 is ineffective in establishing the ter(cid:173)
`mination of a communication session between master trans(cid:173)
`ceiver 64 and a type B trib 66b because the trailing sequence
`is transmitted using type A modulation.
`If, however, master transceiver 64 transmitted a poll
`request in sequence 108, then the type B trib 66b transitions
`to state 116 where it will transmit data, using type B
`modulation, to master transceiver 64 in sequence 118. After
`completion of this transmission, the type B trib 66b returns
`to state 102 where type A transmissions are ignored.
`With reference to FIG. 5 and FIG. 7, a communication
`session between the master transceiver 64 and a type A trib
`66a will now be discussed. A state diagram for a type A trib
`66a is shown in FIG. 7. A type A trib 66a is initialized in
`state 122 in which it awaits a type A modulation training
`sequence. If, however, master transceiver transmits a train-
`ing sequence in which the type A tribs 66a-66a are notified
`of a change to type B modulation as indicated by sequence
`106, then a transition is made to state 124 where all type B
`55 transmissions are ignored until a type A modulation trailing
`sequence (e.g., sequence 114) is detected. Upon detecting
`the type A trailing sequence, a type A trib 66a returns to state
`122 where it awaits a training sequence.
`To initiate a communication session with a type A trib
`66a, master transceiver 64 transmits a training sequence 126
`in which an address of a particular type A trib 66a is
`identified. The identified type A trib 66a recognizes its own
`address and transitions to state 128 to receive data from
`master transceiver 64 as part of sequence 132.
`After completing transmission sequence 132, master
`transceiver 64 transmits a trailing sequence 134 using type
`A modulation signifying the end of the current communi-
`
`40
`
`45
`
`Exhibit 1214 11/14
`
`

`

`US 6,614,838 Bl
`
`5
`
`7
`cation session. If master transceiver 64 has not transmitted
`a poll request to the type A trib 66a in sequence 132, then
`the type A trib 66a that was in communication with the
`master transceiver 64 will return to state 122 after receiving
`trailing sequence 134.
`If, however, master transceiver 64 transmitted a poll
`request in sequence 132, then the type A trib 66a transitions
`to state 136 after receiving trailing sequence 134 where it
`will transmit training sequence 138, followed by data
`sequence 142, and terminated by trailing sequence 144 all 10
`using type A modulation. After completion of these
`transmissions, the type A trib 66a returns to state 122 to
`await the next type A modulation training sequence by
`master transceiver 64.
`The control programs 78 and 92 of the present invention
`can be implemented in hardware, software, firmware, or a
`combination thereof. In the preferred embodiment(s), the
`control programs 78 and 92 are implemented in software or
`firmware that is stored in a memory and that is executed by 20
`a suitable instruction execution system.
`
`15
`
`8
`1. A communication system, comprising:
`a master transceiver;
`a communication medium;
`a plurality of tributary transceivers in communication
`with said master transceiver over said communication
`medium, a first one of said tributary transceivers using
`a primary modulation method for communication over
`said communication medium and a second one of said
`tributary transceivers using a secondary modulation
`method for communication over said communication
`medium;
`said master transceiver including a processor and a stor(cid:173)
`age medium in communication with said processor,
`said storage medium having program code for exchang(cid:173)
`ing information over said communication medium, said
`program code comprising:
`first logic configured to establish said primary modu(cid:173)
`lation method for communication over said commu(cid:173)
`nication medium;
`second logic configured to transmit a training sequence
`to notify said first one of said tributary transceivers
`of a change from said primary modulation method to
`said secondary modulation method;
`third logic configured to transmit information to and
`receive information from said second one of said
`tributary transceivers using said secondary modula(cid:173)
`tion method;
`fourth logic configured to transmit a trailing sequence
`using said primary modulation method to notify said
`first one of said tributary transceivers of a change
`from said secondary modulation method to said
`primary modulation method; and
`fifth logic configured to transmit information to and
`receive information from said first one of said tribu(cid:173)
`tary transceivers using said primary modulation
`method;
`said first one of said tributary transceivers including a
`processor and a storage medium in communication
`with said processor, said storage medium having pro(cid:173)
`gram code for exchanging information over said com(cid:173)
`munication medium, said program code comprising:
`sixth logic configured to detect a change from said
`primary modulation method to said secondary modu(cid:173)
`lation method;
`seventh logic configured to ignore transmissions on
`said communication medium using said secondary
`modulation method; and
`eighth logic configured to detect a trailing sequence
`transmitted using said primary modulation method
`after detecting a change from said primary modula(cid:173)
`tion method to said secondary modulation method;
`said second one of said tributary transceivers including a
`processor and a storage medium in communication
`with said processor, said storage medium having pro(cid:173)
`gram code for exchanging information over said com(cid:173)
`munication medium, said program code comprising:
`ninth logic configured to receive information transmit-
`ted using said secondary modulation method; and
`tenth logic configured to ignore transmissions on said
`communication medium using said primary modu(cid:173)
`lation method.
`2. The communication system of claim 1, wherein said
`60 primary modulation method is selected from the group
`consisting of QAM, CAP, and DMT.
`3. The communication system of claim 1, wherein said
`secondary modulation is selected from the group consisting
`of FSK and PAM.
`4. The communication system of claim 1, wherein said
`third logic is configured to transmit a poll request as part of
`said information.
`
`The control programs 78 and 92, which comprise an
`ordered listing of executable instructions for implementing
`logical functions, can be embodied in any computer(cid:173)
`readable medium for use by or in connection with an 25
`instruction execution system, apparatus, or device, such as a
`computer-based syste