United States Patent
`
`{19]
`
`[11] Patent Number:
`
`5,563,883
`
`[45] Date of Patent: Oct. 8, 1996
`Cheng
`
`
`
`U3005563883A
`
`54] DYNAMIC CHANNEL MANAGEMENT AND
`SIGNALLING METHOD AND APPARATUS
`
`76]
`
`Inventor: Alexander L. Cheng, 11 Sprindale
`Ave, White Plains, NY. 10604
`
`21] Appl. No.: 276,534
`
`22]
`
`Filed:
`
`Jul. 18, 1994
`
`
`
`Int. Cl.6 ....................................................... H0411 1/04
`:51]
`52] US. Cl.
`............................. 370/73; 348/12; 370/857;
`370/858; 455/42; 455/51
`58] Field of Search ............................... 348/6, 9, 12, 13;
`455/31, 4.2, 5.1, 6.1, 34.1; 379/71, 73,
`76, 80, 85.3, 85.7, 85.8, 95.1, 95.2
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,573,206
`5,132,680
`5,224,097
`5,331,316
`5,355,375
`5,374,952
`5,434,611
`
`2/1986 Grauel et al.
`.......................... 455/34,]
`7/1992 Tezuka et a1.
`.. 370/858
`
`6/1993 Kaneshima
`.. 370/858
`7/1994 Mestdagh ............ 370/857
`
`10/1994 Christensen ............................ 370/858
`12/1994 Flohr ......................................... 348/12
`7/1995 Tamura ..................................... 348/12
`
`Primary Examiner~Benediet V. Safourek
`
`[57]
`
`ABSTRACT
`
`services on a multiple access communication system, which
`comprises a central controller, a shared transmission media
`and a plurality of remote terminals dispersed throughout the
`network. The central controller comprises switch and con-
`trol apparatus and a pool of transmitters and receivers. The
`communication channels between the central controller and
`remote terminals are arranged for signalling data and trafiic
`bearer channels in the forward and reverse directions. The
`
`number of signalling data channels is adjusted to satisfy the
`traffic requirements and for redundancy purposes. The for-
`ward and reverse signalling data channels are coupled in
`diflerent mappings to support terminal grouping. Multiple
`access of the remote terminals for the upstream traffic are
`mitigated by separating remote terminals in groups via the
`channel allocation and the terminal assignment process.
`Communication between the central controller and the
`remote terminals follows a multiple access scheme con-
`trolled by the central controller via polling procedure on
`each of the forward signalling data channels independently.
`In case of collision, the central controller engages the remote
`terminals in a selective polling process to resolve the con-
`tention. The overlapping polling method of the controlled
`access scheme increases the utilization of the signalling
`channel and reduces the time required to gain access to the
`shared transmission media. By dynamically adjusting the
`load on signalling data channels, the signalling process is
`greatly improved for efficiency and redundancy against
`anomalies with the added benefit of improved flexibility and
`extensibility. The system is especially useful in a two-way
`CATV network.
`
`There is provided a dynamic and adaptable method and
`apparatus to support two-way multimedia communication
`
`20 Claims, 16 Drawing Sheets
`
`controller
`
`
`
`initialization
`
`terminal
`response
`
`on RD-x'
`
`
`Petitioner Ciseo Systems - Exhibit 1002 - Page 1
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 1
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 1 of 16
`
`5,563,883
`
`I'CIIlOt6
`
`terminals
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 2
`
`H C
`
`D
`v-—(
`F—-(
`
`O$
`
`—t
`4.1
`
`$.21
`
`O O
`
`F—l
`
`C6
`
`H4
`
`.3
`
`G (
`
`D O
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 2
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 2 of 16
`
`'
`
`5,563,883
`
`RD
`FD
`h—k
`
`1—1
`
`m
`
`j
`Figure
`
`3a
`
`’
`
`FD
`n
`
`RD
`0
`
`p
`
`q
`
`Figure
`
`3b
`
`RD
`14
`
`FD
`r
`
`s
`
`t
`Figure
`
`,
`
`3c
`
`controller
`
`initialization
`
`-polling
`
`“5‘5
`
`cycle
`
`YFS
`
`terminal
`response
`on RD—x'
`
`
`
`
`
`N)
`
`YES
`
`YES
`
`contention
`resolution
`
`selective
`13011
`
`terminal
`request
`
`Figure
`
`4
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 3
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 3
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 3 of 16
`
`5,563,883
`
`
`
`terminal
`
`response
`
`
`
`
` YES
`count
`
`
`exceeded
`
`
`
`terminal
`
`failure
`
`successful '
`
`transmission
`
`
`
`
`processing
`
`
`
`polling
`
`cycle
`
`Figure
`
`5
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 4
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 4
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 4 of 16 '
`
`5,563,883
`
`terminal
`
`request
`
`
`
`
`registration
`
`message
`
`
` newly
`registering
`
`terminal
`
`reassign
`ment
`
`
`authorized
`
`
`
`M)
`
`terminal
`
`disable
`
`
`
`available
`capacity
`on other
`
`
`
`terminal
`
`assignment
`
`Figure
`
`6
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 5
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 5
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 5 of 16
`
`_ 5,563,883
`
`
` regis-
`
`
`tration
`
`
`
`x=x'=l
`
`YES
`
`registration
`frame on RD-x
`
`toggle x
`
`between 1/2
`
`
`
`
`YES
`
`retry
`count
`
`
`
`exceeded
`
`
`
`toggle x'
`between 1 2
`
`
`
`
`
`
`
`
`
`terminal
`
`disable
`
`channel
`
`assignment
`set x and x'
`
`
`
`operatio
`
`
`
`Figure 7
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 6
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 6
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 6 of 16
`
`5,563,883
`
`operation
`
`controller
`
`poll or
`command
`
`
`
`tx.
`
`requrred
`
`
`controller
` response
`
`
`
`
`
`
`
`
`error retry
`
`transmission
`
`collision or
`
`successful
`
` Figure 8
`
`terminal
`
`confirmation
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 7
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 7
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 7 of 16
`
`5,563,883
`
`Signalling data frame in the forward
`direction sent by central controller:
`1
`1
`3
`I
`
`Signalling data frame in the reverse
`direction sent by remote terminals:
`1
`1
`3
`1
`EE-_-
`
`bytes
`
`preamble (PMB)
`- sequence to indicate the start of message frame transmission and aid detection of
`collision
`
`Terminal IDentifier (TID)
`-
`terminal identifier for command
`-
`lower TID of the range for the selective poll
`- O (hexadecimal 00)rs an invalid TID used for disabling terminal during the
`registration process (SAT/SRT contains the serial number)
`- 255 (hex FF) for registration process (SAT/SRT contains the serial number)
`Signalling Action Type (SAT)
`- serial number of the remote terminal for channel assignment during registration
`process
`selective poll including higher TID of the range (used also for general/specific poll)
`selective poll with collision alert including higher range (used also for specific poll)
`in-coming call command on the indicated channel number
`release command
`disable command
`test command
`
`- channel re-assignment command
`Signalling Request Type (SRT)
`serial number of the remote terminal for terminal registration process
`on-hook
`off-hook
`switch-hook
`
`ringing
`release
`
`dial-digits
`incoming call blocking
`incoming call unblocking
`feature code (e.g., conference)
`test report
`alarm message (fault and fraud)
`multiple channel request (bandwidth-on-demand)
`- channelized services (sub-rate & multiple channels)
`Frame Check Sequence (FCS)
`- protection, which covers TID and SAT/SRT fields, against transmission error or
`collision
`
`Figure
`
`9
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 8
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 8
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 8 of 16
`
`5,563,883
`
`1
`
`ranges of remote termmals
`
`r01
`
`r1 1
`
`r12
`
`21
`r
`
`r22
`
`23
`
`r
`
`r31
`
`r32
`
`r33
`
`r34
`
`r35
`
`r36
`
`r37
`
`:
`0
`
`:
`O
`
`r24
`
`r38
`
`‘
`
`:
`O
`
`N level of
`halving
`
`0th
`
`lst
`
`2nd
`
`3rd
`:
`I
`
`Fi gu r e
`
`1 0
`
`C0
`
`lines
`
`central
`
`remote
`
`controller
`
`terminals
`
`
`
`119
`
`120
`
`121
`
`122
`
`Figure 11
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 9
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 9
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 9 of 16
`
`5,563,883
`
`hrst poll
`
`
`range r11
`
`
`
`
`
`N)
`
`response YES
`from r11
`
`next poll
`
`range r1 2
`
`N)
`
`response
`
`
`
`
`
`
`
`
`
`
`next.011.rocessingres—ponse from1r1 range_21
`
`
`
` YESpol.ing
`
`
`
`m response YES
`
`
`
`next poll
`range r31
`
`nextpo-lF945
`
`
`
`range-24 continuedm
`
`
`
`
`
`Figure 1 2b
`
`continued in
`
`Figure 12b
`
`Figure 12a
`
`Petitioner Cisco Systems - Exhibit 1002 - PagelO
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 10
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 10 of 16
`
`5,563,883
`
`from
`Figure 12a
`
`from
`Figure 120
`
` response
`from r31
`
`next poll
`
`
`
`
`range r4 1
`
`ponse from r35
`
`
`response
`from r35
`
`processing res—
`
`next poll
`
`range r49
`
`Figure
`
`12b
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 11
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 11
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 11 of 16.
`
`5,563,883
`
`
`
`A9192”
`time."€‘A.
`
`1'
`
`E
`E
`=
`E
`
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`3
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`E
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`2
`
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`132
`
`£1
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`
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`‘5
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`
`3»:
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`a
`3
`
`—
`g
`=
`3
`
`Figure
`
`13a
`
`Figure
`
`13b
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 12
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 12
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 12 of 16
`
`5,563,883
`
`
`
`first poll
`
`range r11
`
`collisio
`
`repeated
`
`tx. error
`
`processing
`
`polling
`
`cycle
`
`
`
`YES
`
`next poll
`range r23
`
`
`
`
`
`response
`
`
`
`from 112
`
`polling
`cycle
`
`processing res-
`ponse from r11
`
`next poll
`range r21
`
`YES
`
`a
`
`polling
`
`cycle
`
`a
`
`continued in
`Figure 14b
`
`‘
`_
`continued in
`Figure 14b
`
`Figure
`
`14a
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 13
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 13
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 13 of 16
`
`5,563,883
`
`from
`
`Figure 1421
`
`from
`
`Figure 1 4a
`
`
`
`
`range r37
`
`next p011
`
`Figure 14b
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 14
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 14
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 14 of 16'
`
`5,563,883
`
`Q)
`
`E
`
`H
`Q)
`~
`'3 .
`h
`...
`=
`O
`9
`
`central
`
`v:
`_
`:8
`s:
`-
`E
`a
`cu
`id
`
`remote
`
`Figure
`
`15
`
`Petitioner Cisco Systems - EXhibit 1002 - Page 15
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 15
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 15 of 16
`
`5,563,883
`
`
`
`_—>
`
`168
`
`167
`
`
`
`
`switching
`matrix
`
`
`
`—-|
`
`12
`
`
`
`Figure
`
`16
`
`10
`
`Petitioner Cisco Systems - Exhibit 1002 -’Page 16
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 16
`
`

`

`US. Patent
`
`Oct. 8, 1996
`
`Sheet 16 of 16
`
`5,563,883
`
`t
`
` telephone
`
`
`Isystembus
`
`38
`
` demod
`
`
`
`V
`-o.¢
`
`—--am - lifier
`filter
`
`Figure
`
`17
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 17
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 17
`
`

`

`5,563,883
`
`1
`DYNAMIC CHANNEL MANAGEMENT AND
`SIGNALLING METHOD AND APPARATUS
`
`FIELD OF THE INVENTION
`
`The present invention pertains generally to methods and
`apparatus for facilitating the two-way multi—media commu—
`nication based on a shared transmission media such as
`coaxial cable-TV network, and more specifically to methods
`and apparatus for signalling channel management and pro—
`tocol.
`
`BACKGROUND OF THE INVENTION
`
`A multiple access communication system comprises a
`central controller, a shared transmission media and a plu-
`rality of remote terminals dispersed geographically. To pro-
`vide the means for multiple access is a classical problem in
`communication systems with a shared common transmission
`media. Some of the well known schemes are frequency
`division multiple access or FDMA, time division multiple
`access or TDMA, and code division multiple access or
`CDMA. These multiple access schemes deal with the tech-
`niques of separating the communication bandwidth into
`traflic-bearing channels. In a FDMA scheme, the commu—
`nication bandwidth is divided into the frequency bands. The
`TDMA scheme separates the communication bandwidth into
`time slots. The traffic is encoded and then decoded using
`different code in a CDMA scheme.
`
`In all these multiple access schemes the contention for
`access is resolved through signalling protocols on a pre-
`determined and fixed signalling channel. There are propos—
`als to dynamically allocate traffic—bearing channels to meet
`the service requirements in terms of lower blocking prob—
`ability. However, in addition to availability, bandwidth and
`delay of the traffic—bearing channel, the traffic requirements
`should include responsiveness of the signalling process and
`the quality of the transmission means.
`The signalling protocols for multiple access communica-
`tion systems fall in two general categories for resolving the
`possible contention: scheduled access via polling or other
`means, and random access contention. In radiotelephony and
`local-area-network (CSMA/CD) environment, the conten-
`tion is resolved by monitoring the signal during transmis-
`sion, which requires synchronization and/or means to moni-
`tor activities amongst all remote terminals and the central
`controller. In the CATV network, remote terminals have
`different distance from the central controller making syn-
`chronization difficult. It is also not feasible to detect colli-
`sion, i.e., multiple remote terminals transmit at the same
`time, on the CATV network since the remote terminals are
`attached to different branches of the network. The poll and
`response method is often used to schedule the multiple
`access from plurality of remote terminals, but it has the
`disadvantage of ineflicieney due to wasteful interaction with
`remote terminals that are not in need of servicing.
`
`DESCRIPTION OF THE RELATED ART
`
`There are many proposals of means for dynamically
`adjusting the number of traffic-bearing channels according
`to varying trafiic demands or the transmission quality in the
`radio telephony environment, e.g., U.S. Pat. Nos. 5,134,709,
`5,235,631 and 5,276,908. In addition U.S. Pat. No. 4,868,
`811 discusses the protocol over the common signalling
`channel for allocation of trafiic-bearing channels. U.S. Pat.
`No. 4,870,408 proposes a process of re-assigning subscriber
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`2
`units to balance the traflic load over the available channels.
`U.S. Pat. No. 5,010,329 discloses a method for dynamically
`grouping terminals in blocks for which the central unit
`performs block polling on a common data channel. The
`present invention presents a method to dynamically allocate
`both signalling data and traflic-bearing channels and to
`dynamically assign remote terminals to these channels.
`The polling scheme is commonly used to resolve conten-
`tion in a multiple access system. U.S. Pat. No. 4,385,314
`proposes a system to sequentially poll all terminals. Due to
`the inherent inefficiency with sequential polling method,
`some proposals with the following variations for perfor—
`mance improvement have been presented. U.S. Pat. No.
`4,754,426 proposes a two-level polling scheme with distrib—
`uted control. U.S. Pat. No. 4,829,297 proposes use of a high
`priority group. U.S. Pat. No. 4,868,816 proposes a binary
`polling scheme, similar to the polling scheme in the present
`invention, with terminal address in each poll. U.S. Pat. No.
`4,924,461 proposes a method to register other pending
`request on a second channel to interrupt sequential polling.
`U.S. Pat. No. 4,942,572 proposes a dual rate polling method
`using pseudo random sequence at high rate to poll all
`terminals resulting possibly in contention with a small
`number of terminals, and following the high rate poll by
`specific poll at lower rate in case of collision. This invention
`diifers from the prior art in that multiple access is controlled
`through overlapping polling sequence executing on multiple
`channels in a parallel fashion. Only when collision occurs,
`this method will enter a selective polling sequence for
`contention resolution. The added benefit of this method is
`efficiency and redundancy against anomalies such as inter-
`ference and component failure.
`
`OBJECTS OF THE INVENTION
`
`To overcome the problems mentioned above, the objec—
`tive of the present invention is to present
`A flexible and extensible method for signalling charmel
`management;
`A flexible and extensible method for assigning remote
`temiinals to the signalling charmels;
`An ellicient asynchronous signalling protocol.
`In the present invention, a dynamic process is disclosed to
`adjust the number of signalling channels to meet the require-
`ments of varying traffic demand and the system growth. This
`is important in carrying multi-media trafiic with different
`requirements in both the traffic—bearing channel bandwidth
`and the time required to setup a traffic-bearing channel. This
`dynamic signalling channel allocation and terminal assign-
`ment method also aids in system redundancy for anomalies
`such as interference and component failure. Integrated with
`the channel allocation and terminal assignment process, the
`present invention also presents an efiicient controlled mul—
`tiple access method. The central controller initiates the
`general polling on each signalling data channel in parallel to
`solicit request from all terminals assigned to the signalling
`data channel. Only when collision is detected, the central
`controller starts to poll selectively for resolution.
`Further objects and advantages of my invention will
`become apparent from considerations of the drawings and
`ensuing description thereof.
`
`BRIEF SUMMARY OF THE INVENTION
`
`The multiple access conununication system architecture
`depicted in FIG. 1 comprises a plurality of remote terminals,
`a common shared transmission media, a central controller
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 18
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 18
`
`

`

`3
`
`4
`
`5,563,883
`
`and interface to wide area networks. There are provided a
`number of communication channels (L) to the wide area
`networks, a number of communication channels (M) for
`supporting a plurality of remote terminals (N). The M
`number of channels to support communication between the
`central controller and the remote terminals are separated into
`four categories as depicted in FIG. 2, for carrying signalling
`data and user traflic in the forward and reverse directions,
`i.e., forward signalling data or FD channel, forward traffic
`bearer or FB channel, reverse signalling data or RD channel,
`and reverse trafiic bearer or RB channel. A11 communication
`signals between the central controller and the remote termi-
`nals are multiplexed onto the shared transmission media.
`The remote terminals are equipment supporting the users’
`communication need and are distributed throughout
`the
`network. For simplicity reason, the summing device for
`signals from remote terminals are shown as a single device
`in FIG. 1. Each of the remote terminals has one RF data
`demodulator capable of receiving data on the assigned FD
`channel, one frequency agile receiver capable of tuning to
`the assigned FB channel, one RF data modulator capable of
`transmitting data on the assigned RD channel, and one
`frequency agile transmitter capable of tuning to the assigned
`RB channel. The central controller comprises a switch and
`control mechanism, and a pool of transmitters and receivers
`for the communication channels. The central controller
`provides concentration and control function to meet the
`communication demand of the remote terminals much the
`same way as a Private Automated Branch eXchange or
`PABX. The central controller also translates the signalling
`information according to the requirement of the network.
`There are two levels of concentrations provided with this
`system: contention in the shared transmission media via the
`signalling protocol, and through the switching matrix of the
`central controller.
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`The signalling channels are dynamically adjusted for
`efliciency and redundancy. This also adds to the extensibility
`of the system for the increasing trafiic load and system
`growth. The downstream trafiic on these channels are sched-
`uled by the central controller. Multiple access of the remote
`terminals for the upstream traffic are mitigated by separating
`remote terminals in groups via the channel allocation and the
`terminal assignment process. Prompted by the remote ter—
`minals at startup, or through the failure recovery procedure,
`or deemed necessary by the central controller, the channel
`allocation and terminal assignment process are initiated and
`controlled by the central controller. Through the registration
`process, the central controller assigns the remote terminal to
`a group supported by coupling of the specific forward and
`reverse signalling data channels. Afterwards, the communi-
`cation between the central controller and the remote terrni—
`nals follows a two-phase process. The controlled multiple
`access method is used, on each forward signalling data
`channel in parallel, for sporadic user data transfer or sig-
`nalling purpose. The central controller either sends com-
`mand to a specific remote terminal or solicits requests via a
`general poll from remote terminals assigned to the forward
`signalling data channel. The remote terminals respond to the
`controller’s poll to request services. The selective polling
`process is used to identify the remote terminals involved in
`case of collision. The traffic bearer channel is used once the
`circuit is established via signalling protocol over the signal-
`ling data channels. The controlled multiple access scheme
`using overlapping polling method represents an efficient
`asynchronous signalling method and the decision process is
`designed to improve the effectiveness of the selective poll-
`ing coverage during the contention resolution process.
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`Accordingly the achieved benefits of the present invention
`are:
`
`General communication channels management architec—
`ture;
`
`Flexible and extensible scheme for signalling channel
`management;
`
`Flexible and extensible scheme for assigning remote
`terminals to the signalling channels;
`Flexible and extensible scheme for supporting system
`growth and new services requirements;
`Improved system redundancy;
`Efiicicnt asynchronous signalling protocol.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Other objects, features and advantages of the invention
`will be apparent from the following Description of the
`Preferred Embodiment taken together with the accompany-
`ing drawings in which:
`FIG. 1 is a illustration of a multiple access communication
`system architecture with interconnections between the
`remote temrinals, the central controller which comprises the
`switch and control module and a number of transmitters and
`receivers, and the wide—area network.
`FIG. 2 shows the channelization of the communication
`bandwidth of the shared transmission media between the
`central controller and the remote terminals for different
`functions.
`
`FIG. 3 depicts the possible mappings of forward and
`reverse signalling data channels.
`FIG. 4 depicts the logic flow diagram for polling and
`registration process at the central controller.
`FIG. 5 depicts the logic flow diagram for command
`process at the central controller.
`FIG. 6 is the logic flow diagram for registration, terminal
`reassignment, channel allocation, and terminal assignment
`process at the central controller.
`
`FIG. 7 depicts the logic flow diagram for registration
`process at the remote terminals.
`
`FIG. 8 depicts the logic flow diagram for signalling
`process at the remote terminals.
`FIG. 9 details the message format for the signalling
`protocol between the central controller and the remote
`temiinals.
`
`FIG. 10 shows the ranges of remote terminals for selective
`polling during the contention resolution process.
`FIG. 11 is a message exchange diagram for signalling
`protocol between the central controller and the remote
`terminals illustrating a scenario of collision and its resolu-
`tion.
`
`FIG. 12 is the decision graph for contention resolution
`process using polling ranges as defined in FIG. 10 using the
`regular polling method.
`FIG. 13 contains signalling message exchange diagrams
`for comparison of two methods using the regular and the
`overlapping polling cycle.
`FIG. 14 is the decision graph for contention resolution
`process using polling ranges as defined in FIG. 10 using the
`overlapping polling method.
`FIG. 15 is a message exchange diagram using the over—
`lapping polling method for signalling protocol between the
`central controller and the remote terminals illustrating a
`scenario of collision and its resolution.
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 19
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`Petitioner Cisco Systems - Exhibit 1002 - Page 19
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`FIG. 16 is the system block diagram of the central
`controller for supporting telephone services.
`FIG. 17 is the system block diagram of a remote terminal
`for supporting telephone services.
`
`DESCRIPTION OF PREFERRED EMBODIMENT
`
`The multiple access communication system architecture
`as depicted in FIG. 1 comprises a central controller 10, a
`shared transmission media 12, and plurality of remote ter-
`minals 14 dispersed geographically throughout the network.
`A pool of communication channels 16 (L) are provided to
`the wide area networks 18, a pool of communication chan-
`nels 20 (M) for supporting a plurality of remote terminals 14
`(N). The M number of channels to support communication
`between the central controller 10 and the remote terminals
`1.4 are separated into four categories for carrying signalling
`data and user trafliic in the forward and reverse directions,
`i.e., forward signalling data or FD channel 22, forward traffic
`bearer or FB channel 24, reverse signalling data or RD
`channel 26, and reverse traflic bearer or RB channel 28. All
`communication signals between the central controller 10 and
`the remote terminals 14 are multiplexed onto the shared
`transmission media 12. All remote terminals 14 are equip-
`ment supporting the users’ communication need and are
`distributed throughout the network. For simplicity reason,
`the summing device 30 for signals from remote terminals are
`shown as a single device in FIG. 1. In a CATV network, this
`summing device 30 represents the splitters and taps con—
`necting the branches that make up the network.
`The central controller 10 comprises a switch and control
`' mechanism 32, and a pool of transmitters, called forward
`signalling data channel (FD) 22 and forward traffic bearer
`channel (FB) 24, and a pool of receivers, called reverse
`signalling data channel (RD) 26 and reverse traflic bearer
`channel (RB) 28. The central controller provides concentra-
`tion and control
`function to meet
`the communication
`demand of the remote terminals much the same way as a
`Private Automated Branch exchange or PABX. The central
`controller also translates the signalling information accord-
`ing to the requirement of the network. In addition to con-
`centration provided through the switching matrix of the
`central controller, contention in the shared transmission
`media via the signalling protocol provides another level of
`concentration with this system.
`Each of the remote terminals has one radio frequency
`(RF) agile data demodulator capable of receiving on the
`assigned FD channel 34, one RF agile receiver tuned to the
`assigned FB channel 36, one RF agile data modulator
`capable of transmitting on the assigned RD channel 38, and
`one RF agile transmitter tuned to the assigned RB channel
`40.
`
`Although the present invention is useful for interworking
`with a variety of different wide area networks, the telephone
`network will be used hereinafter to illustrate the present
`invention.
`
`As depicted in FIG. 2, the bandwidth is channelized for
`carrying traffic in the forward and the reverse direction. Data
`channels are used for carrying signalling or data traffic while
`bearer channels are used for carrying user traffic similar to
`circuits in telephony. Therefore, there are altogether 4 types
`of channels as depicted in FIG. 2. FD-x is the signalling data
`channel in the forward direction 44, i.e., from the central
`controller to the remote terminals, numbered from 1
`to a.
`FB-y is traffic bearer channel 46 in the forward direction
`numbered from 1 to b. RD—x’ is signalling data channel 48
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`in the reverse direction, i.e., from the remote terminals to the
`central controller, numbered from I
`to c. RB—y’ is traflic
`bearer channel 50 in the reverse direction numbered from I
`to d. A guard band 42 is also shown to separate the signals
`traveling in the forward and the reverse directions if they are
`to be put side—by—side. As explained later a and c should be
`greater than or equal to 2 for redundancy reason. Note that
`if the channels are of equal size, then a+b and c+d shall
`remain constant if all channels are available free of inter-
`ference problem, i.e., there are a pool of channels from the
`central controller to the remote terminals, and a separate
`pool of channels from the remote terminals to the central
`controller. These pools are set aside for a flexible allocation
`scheme to be described in detail later.
`
`Although it is not necessary to have all channel to have
`equal bandwidth, the communication process can be man-
`aged more easily if the channels have simplified structure
`with equal bandwidth. In case of equal size of the FD and FE
`channels, the management scheme can relocate the FD to a
`channel that is better suited for data transmission while FB
`channel carrying normal voice communication can tolerate
`a considerable more noisy channel than FD channel is able
`to. Similarly, the management process can take advantage of
`the flexibility afforded by the equal size of the RD and RB
`channels. If the bandwidth of the communication channels
`to the wide area network is equivalent to the charmels of the
`shared transmission media, the number L is less than or
`equal to the number M, which in turn is less than or equal
`to the number N. In case of channels with different sizes the
`central controller needs to have the additional intelligence
`for managing these channels efiiciently, and to perform
`segmentation and reassembly. Note that communication
`with asymmetric bandwidth requirement such as multi—east
`can be efliciently supported in this system.
`The FB-y and RB~y’ channels are allocated according to
`the signalling protocol communicated over the FD-x and
`RD-x’ channels. There is no contention in the forward
`direction, i.e., the traflic on each FD-x channel is scheduled
`independently. The number of signalling data channels are
`used to improve the efficiency servicing groups of remote
`terminals and the system redundancy. In case of transmis-
`sion failure (detected through a number of retries without
`receiving acknowledgment), the central controller reverts
`back to FD-l and then FD-2 for transmission to the specific
`remote terminal, while the remote terminals reverts back to
`RD-l and then RD-2 for transmission and to FD-l and FD-2
`for reception. The FD~1 and FD-2 channels are called
`primary forward signalling data channel and backup forward
`signalling data channel respectively. These RD-l and RD-2
`channels are called primary reverse signalling data channel
`and backup reverse signalling data channel respectively.
`With this general channelization architecture, a flexible
`management scheme is possible for channel arrangement
`and remote terminals grouping. For example, channel
`arrangement can be adjusted according to traffic pattern mix
`and/or more intelligent management scheme can be imple-
`mented with various priority lists. The channelization is
`shown to follow a FDMA scheme for ease of understanding,
`but this can also be easily adopted for TDMA or CDMA
`schemes.
`
`Multiple access of the remote terminals for the upstream
`traffic are mitigated by separating remote terminals in
`groups via the channel allocation and the terminal assign-
`ment process to be described later. The contention among
`remote terminals in each group is resolved through a con-
`trolled multiple aeeess followed by selective polling in case
`of collision on each of the signalling data channel. The
`
`Petitioner Cisco Systems - Exhibit 1002 - Page 20
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`Petitioner Cisco Systems - Exhibit 1002 - Page 20
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`7
`number of remote terminals assigned to each of the RD
`channel is to be evenly distributed according to the traffic
`demand In the case of identical traffic requirements from all
`users, the number of remote terminals assigned to each of
`the RD channel will be equal.
`The mapping of forward and reverse signalling data
`channels is under the control of the central controller
`dynamically. The mapping of part (a) of FIG. 3 depicts the
`simplest arrangement with each pair of forward and reverse
`signalling data channels forming a terminal group. For
`example, the terminal group receiving on FD—h channel will
`transmit on RD-k. The part (b) depicts the one—to—many
`mapping where the central controller transmits on one FD-n
`channel while the remote terminals belonging to the same
`group respond in their assigned RD-o, RD-p, and RD—q
`channel respectively. In part (c) with the many-to-one map-
`ping shows that the central controller transmits on several
`FD (r, s and t) channels each reaching a subset of the group
`of the remote terminals, which respond in the same RD-u
`channel. Depending on the traflic pattern, some mapping
`will be more eflicient in utilizing the bandwidth, e.g., the
`many-to-one mapping as depicted in part (b) of FIG. 3 is
`suitable for case where the traffic coming from the remote
`terminals far exceeds the trafiic in the forward direction.
`Note that the mapping of part (c) can cause collision from
`remote termina