REMB-0109
`
`SYSTEM AND METHOD OF COMMUNICATION VIA EMBEDDED MODULATION
`
`CROSS REFERENCE TO RELATED APPLICATION
`
`[0001] This application is a continuation of U.S. Application No. 11/774,803, filed on
`
`July 9, 2007, which is a continuation ofU.S. Application No. 10/412,878, filed April 14, 2003,
`
`which is a continuation-in-part ofU.S. Application No. 09/205,205, filed December 4, 1998, and
`
`which claims priority to and the benefit of the filing date ofU. S. Provisional Application No.
`
`60/067,562, filed December 5, 1997, each of which is incorporated by reference herein.
`
`TECHNICAL FIELD
`
`[0002] The present invention relates generally to the fields of 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
`
`[0003]
`
`In existing data communications systems, a transmitter and receiver modem pair
`
`can successfully communicate only when the modems are compatible at the physical layer. That
`
`is, the modems must use compatible modulation methods. 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 architecture, all modems operate, for example, in the industry standard V.27bis mode.
`
`- 1 -
`
`Exhibit 1009 01/22
`
`

`

`REMB-0109
`
`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 session. Should it become necessary to change modulation methods, the existing
`
`data session is tom 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 modems.
`
`[0004] As discussed in the foregoing, communication between modems is generally
`
`unsuccessful unless a common modulation method is used. In a point-to-point network
`
`architecture, if a modem attempts to establish a communication 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 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.
`
`[0005]
`
`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, repeated attempts by
`
`the master to communicate with the incompatible trib(s) will disturb communications with
`
`compatible trib(s) due to time wasted in making the futile communication attempts.
`
`[0006] Thus, communication systems comprised of both high performance and low or
`
`moderate performance applications can be very cost inefficient to construct. For example, some
`
`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 applications (e.g., power monitoring and control)
`
`require only modest data rates and therefore a low performance modulation 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 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
`
`compatibility imposes a substantial cost that is unnecessary in terms of the service and
`
`performance to be delivered to the end user.
`
`[0007] 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
`
`-2-
`
`Exhibit 1009 02/22
`
`

`

`REMB-0109
`
`used to facilitate communication among a plurality of modems in a network, which have
`
`heretofore been incompatible.
`
`SUMMARY
`
`[0008] 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 second tributary transceiver over a
`
`communication medium. The first tributary transceiver uses a primary modulation method for
`
`communication 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 normally 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 modulation 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 primary modulation transmissions.
`
`[0009] The present invention has many advantages, a few of which are delineated
`
`hereafter as merely examples.
`
`[0010] 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.
`
`[0011] Another advantage of the present invention is that a master transceiver can
`
`communicate seamlessly with tributary transceivers or modems using incompatible modulation
`
`methods.
`
`[0012] Another advantage of the present invention is that a master and tributary
`
`transceiver can calculate a channel parameter using a test signal sent using embedded
`
`modulation.
`
`-3-
`
`Exhibit 1009 03/22
`
`

`

`REMB-0109
`
`[0013] Other features and advantages of the present invention will become apparent to
`
`one with skill in the art upon examination of the following drawings and detailed description. It
`
`is intended that all such additional features and advantages be included herein within the scope
`
`of the present invention.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0014] 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.
`
`[0015] FIG. 1 is a block diagram of a prior art multipoint communication system
`
`including a master transceiver and a plurality of tributary transceivers;
`
`[0016] FIG. 2 is a ladder diagram illustrating the operation of the multipoint
`
`communication system ofFIG. 1;
`
`[0017] FIG. 3 is a block diagram of a master transceiver and tributary transceiver for
`
`use in the multipoint communication system of FIG. 1 in accordance with the principles of the
`
`present invention;
`
`[0018] 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;
`
`[0019] FIG. 5 is a ladder diagram illustrating the operation ofthe multipoint
`
`communication system ofFIG. 4;
`
`[0020] FIG. 6 is a state diagram for a tributary transceiver of FIGS. 3-5 using a
`
`secondary modulation method in accordance with the principles of the present invention;
`
`[0021] FIG. 7 is a state diagram for a tributary transceiver of FIGS. 3-5 using a primary
`
`modulation method in accordance with the principles of the present invention; and
`
`[0022] FIG. 8 is a ladder diagram illustrating the operation of an alternative
`
`embodiment of the multipoint communication system ofFIG. 4.
`
`DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
`
`[0023] While the invention is susceptible to various modifications 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
`
`-4-
`
`Exhibit 1009 04/22
`
`

`

`REMB-0109
`
`invention to the particular form disclosed, but on the contrary, the invention is to cover all
`
`modifications, equivalents, and alternatives falling within the spirit and scope of the invention as
`
`defined by the claims.
`
`[0024] With reference to FIG. 1, a prior art multipoint communication system 22 is
`
`shown to comprise a master modem or transceiver 24, which communicates with a plurality of
`
`tributary modems (tribs) or transceivers 26-26 over communication 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 communication can begin in multipoint system 22, the master
`
`transceiver 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 commonly referred to as
`
`training signals and can be used for the following purposes: 1) to confirm that the common
`
`modulation method is available, 2) to establish received signal level compensation, 3) to
`
`establish time recovery and/or carrier recovery, 4) to permit channel equalization and/or echo
`
`cancellation, 5) to exchange parameters for optimizing 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
`
`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 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.
`
`[0025] Referring now to FIG. 2, an exemplary multipoint communication session is
`
`illustrated through use of a ladder 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 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 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 sequence 38, which
`- 5-
`
`Exhibit 1009 05/22
`
`

`

`REMB-0109
`
`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.
`
`[0026] 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 modern
`
`that will return a transmission. Thus, trib 26a transmits data 44 destined for master transceiver
`
`24 followed by trailing sequence 46 to terminate the communication session.
`
`[0027] The foregoing procedure is repeated except master transceiver 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 transmits data 58 to master transceiver 24
`
`terminated by trailing sequence 62.
`
`[0028] The foregoing discussion is based on a two-wire, half-duplex multipoint system.
`
`Nevertheless, it should be understood that the concept is equally applicable to four-wire systems.
`
`[0029] 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
`
`transceiver 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 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 protocol.
`
`[0030] 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
`-6-
`
`Exhibit 1009 06/22
`
`

`

`REMB-0109
`
`a lower data rate for other applications, such as power monitoring and control. The needs of
`
`these different applications cannot be efficiently met by a single modulation. 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 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.
`
`[0031] A block diagram of a master transceiver 64 in communication 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 communication 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.
`
`[0032] Trib 66 comprises CPU 82 in communication with modulator 84, demodulator
`
`86, and memory 88. Memory 88, likewise holds software control program 92 and any data
`
`necessary for the operation oftrib 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 modulation method, type X refers to one of those two modulation methods.
`
`The master transceiver 64 communicates with trib 66 over communication medium 94.
`
`[0033] 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 method (e.g., type A) after an initial training sequence.
`
`This allows the master transceiver 64 to communicate seamlessly with tribs of varying types.
`
`[0034] The operation of multipoint communication system 100 will be described
`
`hereafter with reference to the ladder diagram of FIG. 5 and the state diagrams of FIGS. 6 and 7.
`
`A communication session between the master transceiver 64 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 transmissions are ignored. In the present
`
`example, the primary 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
`-7-
`
`Exhibit 1009 07/22
`
`

`

`REMB-0109
`
`responds only to type B modulation transmissions, only the type A tribs 66a-66a are receptive to
`
`transmission sequence 1 04.
`
`[0035] 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 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 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 transmitted in sequence 108.
`
`[0036] 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 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 defined for the type B modulation transmission or transfer of the particular quantity of
`
`data. Note that the trailing sequence 114 is ineffective in establishing the termination of a
`
`communication session between master transceiver 64 and a type B trib 66b because the trailing
`
`sequence is transmitted using type A modulation.
`
`[0037]
`
`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 1 02 where type A transmissions are ignored.
`
`[0038] 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 training 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 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.
`
`- 8 -
`
`Exhibit 1009 08/22
`
`

`

`REMB-0109
`
`[0039] 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.
`
`[0040] After completing transmission sequence 132, master transceiver 64 transmits a
`
`trailing sequence 134 using type A modulation signifYing the end of the current communication
`
`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.
`
`[0041]
`
`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 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.
`
`[0042]
`
`In an alternative embodiment ofthe present invention, embedded modulations
`
`can be used as a way to measure transmission line characteristics between a master transceiver
`
`and tributary transceiver, as shown in FIG. 8. In this embodiment, both a master transceiver 64
`
`and a tributary transceiver 66a would have the ability to transmit using at least two modulation
`
`methods, type A and type B. In the present example, the primary transmission type is type A.
`
`Thus, as shown in FIG. 8, the master transceiver 64 establishes type A as the primary modulation
`
`in sequence 150.
`
`[0043] To switch from type A to type B modulation, master transceiver 64 transmits a
`
`notification sequence 152 to the tributary 66a. Thus, the tributary 66a is notified of an impending
`
`change to modulation type B. The switch to type B modulation could be limited according to a
`
`specific time interval or for the communication of a particular quantity of data, such as a test
`
`signal. After notifYing the tributary 66a of the change to type B modulation, the master
`
`transceiver 64, transmits a test signal sequence 154 using type B modulation.
`
`[0044]
`
`In this embodiment, the tributary transceiver can contain logic which enables the
`
`tributary 66a to calculate at least one channel parameter from the test signal sequence 154.
`
`Channel parameters typically include transmission line characteristics, such as, for example, loss
`
`versus frequency, non-linear distortion, listener echoes, talker echoes, bridge tap locations,
`
`impedance mismatches, noise profile, signal-to- noise ratio, group delay versus frequency, cross-
`
`-9-
`
`Exhibit 1009 09/22
`
`

`

`REMB-0109
`
`talk presence, cross-talk type, etc. Moreover, the tributary transceiver 66a could be configured to
`
`communicate a channel parameter back to the master transceiver 64.
`
`[0045] After transmitting the test signal sequence 154 to the tributary transceiver 66a,
`
`the master transceiver 64 can transmit a trailing sequence 156 to the tributary transceiver 66a
`
`using type A modulation to indicate the end of the transmission using type B modulation. The
`
`master transceiver 64 can then send information to the tributary transceiver 66a using primary
`
`modulation type A, as shown by training, data and trailing sequences 158, 160 and 162.
`
`Likewise, the tributary transceiver 66a can send information to the master transceiver 64 using
`
`primary modulation type A, as shown by training, data and trailing sequences 164, 166 and 168.
`
`[0046]
`
`In a further alternative embodiment, the master transceiver 64 or tributary
`
`transceiver 66a may identify a time period within which test signal sequences may be
`
`transmitted. This would eliminate the training and trailing sequences which alert the tributary
`
`transceiver 66a to the beginning of a new modulation method. The identification of the time
`
`period could be initiated by the master transceiver 64 or tributary transceiver 66a and could
`
`include a time period noted in the header of a transmission between the tributary transceiver 66a
`
`and master transceiver 64.
`
`[0047] 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 a suitable instruction execution system.
`
`[0048] 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 instruction execution system, apparatus, or
`
`device, such as a computer-based system, processor-containing system, or other system that can
`
`fetch the instructions from the instruction execution system, apparatus, or device and execute the
`
`instructions. In the context of this document, a "computer-readable medium" can be any means
`
`that can contain, store, communicate, propagate, or transport the program for use by or in
`
`connection with the instruction execution system, apparatus, or device. The computer readable
`
`medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic,
`
`infrared, or semiconductor system, apparatus, device, or propagation medium. More specific
`
`examples (a nonexhaustive list) of the computer-readable medium would include the following:
`
`an electrical connection (electronic) having one or more wires, a portable computer diskette
`
`(magnetic), a random access memory (RAM) (magnetic), a read-only memory (ROM)
`
`(magnetic), an erasable programmable read-only memory (EPROM or Flash memory)
`- 10-
`
`Exhibit 1009 10/22
`
`

`

`REMB-0109
`
`(magnetic), an optical fiber (optical), and a portable compact disc read-only memory (CDROM)
`
`(optical). Note that the computer-readable medium could even be paper or another suitable
`
`medium upon which the program is printed, as the program can be electronically captured, via
`
`for instance optical scanning of the paper or other medium, then compiled, interpreted or
`
`otherwise processed in a suitable manner if necessary, and then stored in a computer memory.
`
`[0049]
`
`In concluding the detailed description, it should be noted that it will be obvious
`
`to those skilled in the art that many variations and modifications can be made to the preferred
`
`embodiment without substantially departing from the principles of the present invention. All
`
`such variations and modifications are intended to be included herein within the scope of the
`
`present invention, as set forth in the following claims. Further, in the claims hereafter, the
`
`corresponding structures, materials, acts, and equivalents of all means or step plus function
`
`elements are intended to include any structure, material, or acts for performing the functions with
`
`other claimed elements as specifically claimed.
`
`- 11 -
`
`Exhibit 1009 11/22
`
`

`

`REMB-0109
`
`What is Claimed:
`
`1.
`
`A communication system, comprising:
`
`a transmitter capable of transmitting at least two modulation methods, wherein the
`
`at least two modulation methods comprise a first modulation method and a second modulation,
`
`wherein the second method is different than the first modulation method, and wherein the first
`
`transceiver is configured to transmit
`
`a first sequence, in the first modulation method, that indicates an impending change from
`
`the first modulation method to the second modulation method, and
`
`a second sequence, in the second modulation method, wherein the second sequence is
`
`transmitted after the first data sequence.
`
`2. The system of claim 1, wherein the transceiver is configured to transmit a third sequence
`
`after the second sequence, wherein the third sequence is transmitted in the first modulation
`
`method and indicates that communication has reverted to the first modulation method.
`
`3. The system of claim 1, wherein first modulation method is a frequency shift keying
`
`modulation.
`
`4. The system of claim 3, wherein the second modulation method is a shift keying modulation.
`
`5. The system of claim 1, wherein the second modulation method is different than the first
`
`modulation method in performance.
`
`6. The system of claim 5, wherein the first modulation method has a lower performance than
`
`the second modulation method.
`
`7. The system of claim 1, wherein the second modulation method is different than the first
`
`modulation method in data rate.
`
`8. The system of claim 7, wherein the first modulation method has a lower data rate than the
`
`second modulation method.
`
`- 12-
`
`Exhibit 1009 12/22
`
`

`

`REMB-0109
`
`9. The system of claim 1, wherein the first transceiver is configured to transmit the second
`
`sequence according to a specific time interval.
`
`10. The system of claim 1, wherein the first transceiver is configured to transmit the second
`
`sequence according to a particular quantity of data.
`
`11. The system of claim 1, further comprising a processor and a memory, wherein the memory
`
`has stored therein instructions that when executed by the processor cause the transmitter to
`
`transmit the first sequence and the second sequence.
`
`12. The system of claim 11, wherein the memory has stored therein program code for the first
`
`modulation method and the second modulation method.
`
`13. The system of claim 11, wherein the memory comprises random access memory.
`
`14. The system of claim 11, wherein the memory comprises read-only memory.
`
`15. The device of claim 11, wherein the memory has stored therein program code for a
`
`multipoint communications protocol.
`
`16. The system of claim 1, wherein the first sequence comprises an address.
`
`17. The system of claim 1, wherein the first sequence and the second sequence are contained in
`
`a burst transmission.
`
`18. The system of claim 17, wherein the burst transmission is a poll in accordance with a
`
`multipoint communications protocol.
`
`19. A communications device, comprising:
`
`a processor; and
`
`a memory having stored therein executable instructions for execution by the processor,
`
`wherein the executable instructions direct transmission of first data with a first modulation
`
`method followed by second data with a second modulation method, wherein the first modulation
`
`method is different than the second modulation method, and wherein the first data comprises an
`
`- 13-
`
`Exhibit 1009 13/22
`
`

`

`REMB-0109
`
`indication of