Upstream only linecard with front end multiplexer for CMTS

• US 20050010958A1
• Filed: 06/04/2004
• Published: 01/13/2005
• Est. Priority Date: 07/08/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Shlomo Selim Rakib, Yehuda Azenkot
• Inventors: Azenkot, Yehuda, Rakib, Shlomo Selim
• Granted Patent: US 7,490,345 B2
• Time in Patent Office: Days
• US Class Current: 725/111
• CPC Class Codes: H04H 20/78 CATV [Community Antenna Television] systems
• CPC Class Codes: H04L 12/2801 Broadband local area networks
• CPC Class Codes: H04L 27/0002 analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line duplex arrangements H04L5/143
• CPC Class Codes: H04L 5/06 the signals being represented by different frequencies combined with time-division multiplexing H04L5/26

Abstract

An upstream line card including a digital or analog multiplexer front end circuit for a Cable Modem Termination System. Each upstream line card has only upstream receivers and allows a CMTS to share one or a handful of receiver chips to receive and recover data from a larger number of input cables coupled to the front end multiplexer. A control circuit for the multiplexer uses MAP data and burst assignment data and upstream mini-slot counts for each of the input cables to determine when a burst is about to arrive on a cable and cause appropriate switching by the multiplexer or crossbar switch. In some embodiments, there is only one RF channel circuit coupled to the output of the multiplexer, so the multiplexer is controlled to couple the input cable upon which the burst is expected to the single RF channel. In other embodiments, there are multiple RF channels coupled to the inputs of the multiplexer so the multiplexer is controlled to connect each input cable on which a burst is expected to an available RF channel. In some embodiments, the sample data generated by each RF channel is buffered and an arbiter picks one burst at a time for application to the input of a CMTS receiver or doles out bursts to different receivers. In other embodiments, no buffers or arbiter are used, and each RF channel has its own dedicated CMTS receiver.

Claims

1. (FIG. 7 or 9—

no RF tuners) A cable modem termination system receiver upstream line card comprising;

a plurality of RF means each having an input for coupling to a cable of a hybrid fiber coaxial cable system, for preparing a radio frequency burst signal bearing data for analog to digital conversion;

a plurality of analog-to-digital converters (hereafter A/D converter), each having a signal input coupled to receive a signal output by one of said RF means and each having an output;

a digital crossbar switch having a plurality of inputs, each coupled to an output of an A/D converter and having one or more outputs and one or more control inputs for receiving signals which control which of said inputs of said crossbar switch is coupled to which of said outputs of said crossbar switch;

one or more cable modem termination system physical layer receivers (hereafter PHY receiver), each having an input coupled to an output of said crossbar switch and each having an input for receiving at least upstream channel descriptor (UCD) data and MAP data, said UCD data describing upstream logical channels which will carry bursts said PHY receiver is assigned to receive so that said PHY receiver assigned to receive each burst can configure itself properly to received said assigned burst, said MAP data describing when each burst said PHY receiver is assigned to receive will occur, and each PHY receiver having an output at which appears data recovered from each assigned burst said PHY receiver processed;

a control circuit coupled to said one or more control inputs of said crossbar switch and having an input for receiving at least MAP data indicating when authorized bursts on each logical channel on each cable coupled to an input of said crossbar switch will occur, said control circuit for determining which said PHY receiver will be assigned to receive each burst, and for generating control signals to control switching by said digital crossbar switch to couple each said burst to an assigned PHY receiver at a proper time to allow said PHY receiver to receive the bursts assigned to it; and

an upstream media access control circuit for generating said UCD and MAP data, and for outputting said UCD and MAP data to said PHY receivers and said RF means, and for outputting said MAP data to said control circuit, and having a plurality of inputs, each coupled to an output of a PHY receiver to receive data recovered from said bursts, and for receiving upstream messages and generating downstream messages to carry out DOCSIS protocols for at least training and registration of cable modems on the system.

2. (FIG. 7 or FIG. 9 with RF tuners) A cable modem termination system receiver upstream line card comprising:

a plurality of RF means each having an input for coupling to a cable of a hybrid fiber coaxial cable system, for preparing a radio frequency burst signal bearing data for analog to digital conversion, and having an input for receiving DOCSIS UCD and MAP data;

a plurality of analog-to-digital converters (hereafter A/D converter), each having a signal input coupled to receive a signal output by one of said RF means and each having an output;

a digital crossbar switch having a plurality of inputs, each coupled to an output of an A/D converter and having one or more outputs and a number of control inputs equalling the number of outputs, each control input for receiving signals which control which of said inputs of said crossbar switch is coupled to the output of said crossbar switch which is associated with said control input;

one or more cable modem termination system physical layer receivers (hereafter PHY receiver), each having an input coupled to an output of said crossbar switch and each having an input for receiving at least upstream channel descriptor (UCD) data and MAP data, said UCD data describing upstream logical channels which will carry bursts said PHY receiver is assigned to receive so that said PHY receiver assigned to receive each burst can configure itself properly to received said assigned burst, said MAP data describing when each burst said PHY receiver is assigned to receive will occur, and each PHY receiver having an output at which appears data recovered from each assigned burst said PHY receiver processed, and each PHY receiver having an output coupled to a control input of said crossbar switch associated with an output thereof which is coupled to said PHY receiver, each said PHY receiver having a port for receiving communications regarding assignment of bursts to said PHY receiver to process, each said PHY receiver functioning to generate control signals to control switching of said crossbar switch at a proper time so as to couple bursts said PHY receiver has been assigned to process to said input of said PHY receiver;

a control circuit coupled to said ports of said PHY receivers and having an input for receiving at least MAP data indicating when authorized bursts on each logical channel on each cable coupled to an input of said crossbar switch will occur, said control circuit for determining which said PHY receiver will be assigned to receive each burst, and for generating messages assigning each said PHY receiver to receive particular bursts assigned to it; and

an upstream media access control circuit for generating said UCD and MAP data, and for outputting said UCD and MAP data to said PHY receivers and said RF means, and for outputting said MAP data to said control circuit, and having a plurality of inputs, each coupled to an output of a PHY receiver to receive data recovered from said bursts, and for receiving upstream messages and generating downstream messages to carry out DOCSIS protocols for at least training and registration of cable modems on the system.

3. (FIG. 7—

RF tuners or amplifiers only and with gain control and with FIFOs) A cable modem termination system upstream line card, comprising;

a plurality of radio frequency amplifier means for coupling to hybrid fiber coaxial cable system cables and tuning to logical channels and preparing received signals for analog to digital conversion, each radio frequency tuner having a gain control input;

a plurality of analog-to-digital converters, each for sampling at a high enough rate to satisfy the Nyquist criteria for the highest frequency logical channel which might be coupled to an input of said converter;

a digital crossbar switch having a plurality of inputs, each coupled to a signal output of one of said radio frequency tuner means, and having a plurality of outputs, each coupled to an input of an analog-to-digital converter, and having a switching control input for each said output;

a plurality of sample storage FIFOs, each coupled by first data path means to a sample output of an analog-to-digital converter, said first data path means for conveying data from a sample output of each analog-to-digital converter to an input of a FIFO dedicated to storing samples from said analog-to-digital converter;

a plurality of PHY receivers, each coupled by second data path means to an output of one of said plurality of FIFOs, and each having a switching control output coupled to one of said switching control inputs of said digital crossbar switch dedicated to receiving control signals to control coupling of inputs of said crossbar switch to an output of said crossbar switch coupled to said PHY receiver, and each having a plurality of gain control outputs, each coupled to a gain control input of one of said radio frequency tuners;

a plurality of recovered data storage FIFOs, each having an input coupled by third data path means to a recovered data output of one of said PHY receivers, and each having an output;

an arbiter coupled to said PHY receivers for determining which PHY receiver is to receive each burst and for sending messages to each PHY receiver assigning particular bursts said PHY receiver is to receive and supplying necessary UCD and MAP data to said PHY receiver; and

upstream media access control means coupled said outputs of said data storage FIFOs to receive recovered data stored therein and for carrying out all necessary messaging to implement DOCSIS training and registration protocols and for processing recovered data and for defining and assigning channel parameters to each upstream logical channel via a separate upstream channel descriptor message for each said upstream logical channel and for receiving upstream bandwidth requests from each cable modem which has successfully completed training and registered and for making bandwidth grants for each upstream logical channel via downstream MAP messages and for supplying said UCD and MAP data to said arbiter and to said radio frequency tuners.

4. (FIG. 11) A DOCSIS cable modem termination system upstream line card comprising:

means for receiving radio frequency signals bearing DOCSIS data bursts from a plurality of HFC cables, and filtering out noise and amplifying or attenuation said radio frequency signals to make best use of an analog-to-digital converter;

a crossbar switch coupled to said means for receiving via a plurality of inputs and having a plurality of outputs, said switch capable of coupling selected inputs to selected outputs under control of switch commands;

means coupled to said plurality of outputs of said switch for sampling signals appearing at said outputs at a sample rate which is high enough to satisfy the Nyquist criteria for the highest frequency signal which may be encountered and outputting the sample streams of the signals at each output as a separate channel;

means coupled to each said channel output for performing narrowband excision to remove narrow frequency band noise from the samples in each channel;

means for storing the samples of each channel output by said means for performing narrowband excision;

one or more receiver means for processing the samples of each channel to recover data encoded in said DOCSIS data bursts of each channel;

control means for assigning bursts to said receiver means and for controlling switching by said switch so as to couple DOCSIS bursts to the receiver means which have been assigned to receive them;

FIFO means for storing data recovered by each said receiver means; and

upstream media access control (UMAC) means for processing data stored in said FIFO means, said UMAC means for processing upstream DOCSIS message data and generating downstream DOCSIS messages for transmission so as to carry out DOCSIS protocols and for receiving upstream payload data.

5. (FIG. 11 no tuners) An upstream line card for a DOCSIS cable modem termination system, comprising:

a plurality of radio frequency amplifiers, each coupled to a different coaxial cable of one or more hybrid fiber coaxial cable systems, and each having a control input for receiving gain control data or a gain control signal, and each having an RF output;

an RF receiver control circuit having an output coupled to each said control input of said radio frequency tuners for supplying said gain control data or signal;

a plurality of low pass filters, each having an input coupled to said RF output of one of said radio frequency tuners, and each having an output;

a plurality of high pass filters, each having an input coupled to an RF output of one of said radio frequency tuners, and each having an output;

a crossbar switch having a plurality of inputs each coupled to an output of one of said filters, and having a plurality of channel outputs, and having a switch control input for receiving signals or data which control which of said inputs are coupled to which of said channel outputs and when;

a switch control circuit having an output coupled to said switch control input of said crossbar switch, and having an input for receiving burst assignment data, said switch control circuit functioning to generate control signals or data at said output which controls switching by said crossbar switch;

a plurality of analog-to-digital converters (A/D), each having a signal input coupled to one of said channel outputs of said digital switch, and each having a sample output for one channel;

a plurality of narrow band excision (NBX) circuits, each having an input coupled to receive samples for one channel from one of said A/D converters, and each having an input for receiving frequency, sample rate and burst assignment data that defines which bursts are to be processed in each channel, the center frequency of the logical channel in which the burst will be transmitted and the sample rate of the burst, each NBX circuit having an input coupled to receive samples from one of said analog-to-digital converters (A/D) and having a channel output at which filtered sample data appears;

a narrow band excision control circuit which receives UCD, MAP and burst assignment data and sends the appropriate center frequency, sample rate and burst assignment data to each narrow band excision circuit to enable it to efficiently process the logical channel samples for each burst of a channel in which said NBX circuit is coupled;

a first-in-first-out memory having an input coupled to receive and store sample data output at each said channel output of a said NBX circuit;

a plurality of DOCSIS compatible receivers, each having a sample input coupled to an output of one of said FIFO memories, and each having an output at which data recovered from DOCSIS bursts appears, each receiver also having a control input for receiving burst assignment data telling said receiver which DOCSIS bursts each said receiver has been assigned to receive and DOCSIS UCD and MAP message data and burst assignment data to enable each said receiver to configure itself properly to process each burst it has been assigned to receive at the proper time;

an arbiter circuit having an output coupled to said control input of each said DOCSIS compatible receiver, and having an input for receiving UCD and MAP data, said arbiter for determining which of said receivers is to receive each DOCSIS burst authorized by said MAP data of all said logical channels defined by said UCD data, and for sending UCD, MAP and burst assignment data to said receivers, and for sending burst assignment data to said switch control circuit and said narrow band excision control circuit and said RF receiver control circuit;

a second plurality of FIFO memories, each coupled to receive and store the data recovered from DOCSIS burst by one of said receivers;

an upstream media access control circuit for processing upstream DOCSIS data and messages stored in said second plurality of FIFO memories and for composing DOCSIS downstream messages to implement DOCSIS protocols, and for generating UCD message data that defines parameters of a plurality of upstream channels on cables coupled to said inputs to said radio frequency tuners, and for receiving upstream bandwidth requests from cable modems and for generating MAP message data for each upstream logical channel which authorizes transmissions of DOCSIS data bursts at specific times on specific logical channels, and for sending said UCD and MAP data to said arbiter circuit.

6. [FIG. 13—

no RF tuners] An upstream line card receiver for a DOCSIS cable modem termination system, comprising;

a plurality of RF means each having an input for coupling to a cable of a hybrid fiber coaxial cable system, said RF means for preparing a radio frequency burst signal bearing data for analog to digital conversion and having a gain control input for receiving gain control signals, and each having an output;

a crossbar switch having a plurality of inputs, each coupled to an output of one of said RF means and having an output at which a signal selected from one of said inputs appears, and having a control input for receiving control signals or data which control which of said inputs of said crossbar switch is coupled to said output of said crossbar switch;

an analog to digital converter having an input coupled to said output of said crossbar switch and having an output at which samples of any signal appearing at said output of said crossbar switch appear;

a cable modem termination system physical layer receiver (hereafter PHY receiver), having an input coupled to said output of said analog to digital converter, and having an input for receiving at least DOCSIS upstream channel descriptor (UCD) message data and MAP message data, said UCD data describing upstream logical channels which will carry bursts said PHY receiver is assigned to receive so that said PHY receiver can configure itself properly to receive said assigned burst, said MAP data describing when each burst said PHY receiver is assigned to receive will occur, said PHY receiver having an output at which appears data recovered from each assigned burst said PHY receiver processed, said PHY receiver also having an output coupled to said control input of said crossbar switch to supply said control signals or data to control switching by said crossbar switch to couple bursts arriving on said cables to said input of said analog to digital converter, and having an output coupled to said gain control inputs of said RF means for supplying gain control data to each said RF means when a burst to be processed by said PHY receiver arrives at said RF means;

means coupled to receive data recovered from said bursts by said PHY receiver, for carrying out an upstream media access control process to process said recovered data and coordinate with a downstream media access control process to implement DOCSIS protocols and generate UCD and MAP messages for transmitting to cable modems coupled to said cables.

7. [FIG. 12—

either tuners or amplifiers for RF sections, multiple shared receivers which control switching, no buffers] An upstream line card receiver for a DOCSIS cable modem termination system, comprising;

a plurality of RF means each having an input for coupling to a cable of a hybrid fiber coaxial cable system, said RF means for preparing a radio frequency burst signal bearing data for analog to digital conversion, each RF means having an output;

a crossbar switch having a plurality of inputs, each coupled to an output of one of said RF means and having a plurality of outputs at each of which a signal selected from one of said inputs appears, and having a plurality of control inputs, each for receiving control signals or data which controls which of said inputs of said crossbar switch is coupled to a particular one of said outputs controlled by said control input;

a plurality of analog to digital converters, each having an input coupled to an output of said crossbar switch and each having an output at which samples of any signal appearing at said output of said crossbar switch appear;

a plurality of cable modem termination system physical layer receivers (hereafter PHY receiver), each having an input coupled to said output of one of said analog to digital converters, and each having an input for receiving at least DOCSIS upstream channel descriptor (UCD) message data and MAP message data and burst assignment, said UCD data describing upstream logical channels which will carry bursts each said PHY receiver is assigned to receive so that each said PHY receiver can configure itself properly to receive said assigned burst, said MAP data describing when each burst each said PHY receiver is assigned to receive will occur on a logical channel to which said MAP data pertains, each said PHY receiver having an output at which appears data recovered from each assigned burst said PHY receiver processed, each said PHY receiver also having an output coupled to one of said control inputs of said crossbar switch to supply said control signals or data to control switching by said crossbar switch to couple bursts arriving on said cables to an output of said digital switch which said PHY receiver controls and to which said PHY receiver is coupled through an analog to digital converter, and each PHY receiver having one or more outputs coupled to one or more of said gain control inputs of said RF means for supplying gain control data to said RF means;

means coupled to receive data recovered from said bursts by said PHY receivers, for carrying out an upstream media access control process to process said recovered data and coordinate with a downstream media access control process to implement DOCSIS protocols and generate UCD and MAP messages for transmitting to cable modems coupled to said cables.

8. (FIG. 12 or 13 process with tuners, no FIFO, one or more shared receivers) A process carried out in a cable modem termination system for sharing one or more DOCSIS receivers to receive bursts from a larger number of optical nodes in one or more hybrid fiber coaxial cable systems without noise aggregation, comprising:

1) in each of a plurality of RF tuners receiving UCD and MAP data and tuning to a logical channel on coaxial cable on which a DOCSIS upstream data burst is scheduled to arrive, amplifying or attenuating said burst signal as needed in accordance with a gain control signal to prepare the signal for analog to digital conversion and filtering out excess noise and outputting the processed signal from each input of a digital switch;

2) receiving switching commands in a crossbar switch and responding thereto by coupling a selected input to a selected output at a selected time;

3) converting the signal at each output of said crossbar switch to digital samples;

4) processing said digital samples in one or more DOCSIS compatible receiver to recover data encoded into each burst; and

5) processing said recovered data from each burst in an upstream media access control (UMAC) process which carries out DOCSIS training and registration and other protocols and which defines UCD data for each upstream logical channel and receives upstream bandwidth requests and responds thereto by generating MAP data for each logical channel which defines when each cable modem coupled to an upstream logical channel can transmit a burst and coordinating generation of said MAP data for all said logical channels on cables coupled to said inputs of said crossbar switch according to the number of DOCSIS compatible receivers in use and whether or not buffer memory is being used to store sample data generated by said analog to digital converter.

9. The process of claim 8 further comprising the steps of filtering the output of each said tuner in a high pass filter and a low pass filter and coupling the outputs of said low pass and high pass filters to separate inputs of said digital switch.

10. The process of claim 8 wherein said digital switch has a plurality of outputs and wherein step 3 comprises digitizing the signal at each output in an analog to digital converter dedicated to that output to generate a separate stream of output samples for each output of said digital switch, and wherein step 4 comprises processing the samples from each said analog to digital converter in a separate DOCSIS compatible PHY receiver to recover burst data.

11. The process of claim 10 further comprising the step of controlling the gain of each RF tuner using gain control signals from a PHY receiver so as to make full use of the dynamic range of said analog to digital converters and not exceed the linear range of conversion.

12. The process of claim 10 further comprising the step of controlling the gain of each RF tuner using gain control signals generated by said UMAC process.

13. The process of claim 10 further comprising the step of filtering the output sample stream from each analog to digital converter in a narrow band excision filter to remove narrow band interference.

14. The process of claim 10 further comprising the step of storing said output sample stream from each said analog to digital converter in a separate first-in, first-out (FIFO) memory.

15. The process of claim 10 further comprising the step of storing said output data recovered by each of said PHY receivers in a separate first-in, first-out (FIFO) memory.

16. The process of claim 15 further comprising the step generating said gain control signal for each said RF tuner in a PHY receiver and further comprising the step of storing said output sample stream from each said analog to digital converter in a separate first-in, first-out (FIFO) memory.

17. The process of claim 15 further comprising the step of generating said gain control signal for each RF tuner in said UMAC process.

18. The process of claim 15 further comprising the step of generating said gain control signal for each said RF tuner in a PHY receiver and further comprising the step of storing said output sample stream from each said analog to digital converter in a separate first-in, first-out (FIFO) memory and storing data recovered by each said PHY receiver in a separate FIFO memory.

19. The process of claim 15 further comprising the step of generating said gain control signal for each said RF tuner in a PHY receiver and further comprising the step of storing said output sample stream from each said analog to digital converter in a separate first-in, first-out (FIFO) memory and storing data recovered by each said PHY receiver in a separate FIFO memory and further comprising the step of generating switching commands to control switching of each output of said digital switch by a PHY receiver coupled to process sample data generated from a signal appearing at said output.

20. (FIG. 10 process—

no tuners, multiple shared receivers with FIFO, analog crossbar) A process carried out in a cable modem termination system for sharing one or more DOCSIS receivers to receive bursts from a larger number of optical nodes in one or more hybrid fiber coaxial cable systems without noise aggregation, comprising;

1) in each of a plurality of RF amplifier sections receiving radio frequency signals modulated with upstream data symbols and amplifying or attenuating said burst signal as needed in accordance with a gain control signal to prepare the signal for analog to digital conversion and outputting the processed signal from each RF amplifier section to an input of a crossbar switch;

2) coupling a burst signal appearing at a selected input of said crossbar switch to a selected output at a selected time;

3) converting each said burst signal appearing at an output of said crossbar switch to digital samples;

4) storing said samples generated from each said burst signal in a FIFO memory dedicated to storing samples of signals appearing at a particular output;

5) examining UCD and MAP data and determining which bursts authorized in said MAP data will be processed by each of a plurality of DOCSIS compatible receivers and sending UCD and MAP data along with burst assignment data to each PHY receiver to tell each PHY receiver which burst samples it is supposed to process;

6) processing digital samples of bursts stored in each said FIFO memory in a DOCSIS compatible receiver dedicated to processing samples of burst signals appearing at a particular output of said digital switch in accordance with said burst assignment data so as to recover data encoded into each burst.

21. The process of claim 20 further comprising the steps:

7) storing said data recovered by said DOCSIS compatible receiver in a separate FIFO dedicated to storing data recovered by a particular receiver; and

8) processing said recovered data stored in each said FIFO memory in an upstream media access control (UMAC) process which carries out DOCSIS training and registration and other protocols and which defines UCD data for each upstream logical channel and receives upstream bandwidth requests and responds thereto by generating MAP data for each logical channel which defines when each cable modem coupled to an upstream logical channel can transmit a burst, and coordinating generation of said MAP data for all said logical channels on cables coupled to said inputs of said digital switch according to the number of DOCSIS compatible receivers in use and the state of fullness of said FIFO memories.

22. (FIG. 7 or 9 or 12—

no tuners, dig crossbar, one or more shared receivers) A process carried out in a cable modem termination system for sharing one or more DOCSIS receivers to receive bursts from a larger number of optical nodes in one or more hybrid fiber coaxial cable systems without noise aggregation, comprising;

1) in each of a plurality of RF sections receiving radio frequency signals modulated with upstream data symbols and amplifying or attenuating said burst signal as needed in accordance with a gain control signal to prepare the signal for analog to digital conversion and outputting the processed signal from each said RF amplifier;

2) converting each said signal appearing at an output of one of said plurality of RF amplifiers to digital samples and supplying said samples to one of a plurality of inputs of a digital crossbar switch or multiplexer;

3) coupling samples appearing at one or more inputs of said digital crossbar switch or multiplexer to one or more selected outputs of said digital crossbar switch or multiplexer in accordance with burst assignment data;

4) examining UCD and MAP data and determining which bursts authorized in said MAP data will be processed by each of one or more PHY DOCSIS compatible receivers and sending UCD and MAP data along with burst assignment data to each PHY receiver to tell each PHY DOCSIS compatible receiver which burst samples it is supposed to process;

5) processing said digital samples of bursts in one of said one or more DOCSIS compatible receivers so as to recover data encoded into each burst.

23. (adds FIFO—

FIG. 10 or) The process of claim 22 further comprising the step of storing said samples appearing at each output of said digital crossbar switch or multiplexer in a FIFO memory dedicated to storing samples of signals appearing at a particular one of said one or more outputs of said crossbar switch or multiplexer prior to processing by said PHY receiver.

24. (adds tuners) The process of claim 22 wherein said RF sections tune to specific upstream logical channels using UCD, MAP and burst assignment data, amplify by a gain level established in a predetermined way, down convert the logical channel signals to baseband, digitize and filter using a digital filter having its coefficients set according to UCD data to match the bandwidth of said upstream logical channel.

25. (adds coordinated MAP process to step 22) The process of claim 22 wherein said PHY receivers or DOCSIS compatible and further comprising the step of coordinating MAP messages and downstreams associated with a group of upstreams to be received by one or more shared upstream PHY receivers so that said downstreams are synchronized and said MAP messages define the same contention intervals for all said upstreams and authorize bursts on said upstreams that are to be received by one or more shared DOCSIS receivers such that there is either no overlap in upstream bursts from said different optical nodes or the number of overlapping bursts from different optical nodes in a group does not exceed the number of shared DOCSIS compatible receivers available to receive the bursts.

26. (adds coordinated MAP process to FIFO based process of claim 23) The process of claim 22 wherein said PHY receivers or DOCSIS compatible and further comprising the step of coordinating MAP messages and downstreams associated with a group of upstreams to be received by one or more shared upstream PHY receivers so that said downstreams are synchronized and said MAP messages define the same contention intervals for all said upstreams and authorize bursts on said upstreams that are to be received by one or more shared DOCSIS receivers such that there is either no overlap in upstream bursts from said different optical nodes or the number of overlapping bursts from different optical nodes in a group does not exceed the number of shared DOCSIS compatible receivers available to receive the bursts.

27. (Generic process, no FIFOs, controlled overlap) A process carried out in a cable modem termination system for sharing one or more DOCSIS receivers to receive bursts from a larger number of optical nodes in one or more hybrid fiber coaxial cable systems without noise aggregation, comprising:

1) coordinating MAP messages and downstreams associated with a group of upstreams to be received by one or more shared upstream DOCSIS compatible receivers so that said downstreams are synchronized and said MAP messages define the same contention intervals for all said upstreams and authorize bursts on said upstreams that are to be received by one or more shared DOCSIS receivers such that there is either no overlap in upstream bursts from said different optical nodes or the amount of overlap does not exceed the number of shared DOCSIS receivers available to receive the bursts;

2) receiving upstream radio frequency transmissions from a plurality of different optical nodes of one or more HFC systems;

3) selecting one or more signals or sets of samples from one or more optical nodes in an analog multiplexer or digital crossbar switch for reception and coupling each selected signal or set of samples to an input of a shared DOCSIS receiver;

4) if the selected signal or signals have not been digitized by sampling, sampling said one or more selected signals before coupling said samples to said inputs of said one or more shared DOCSIS receivers.

28. (FIG. 7 or 9 or 12 process with coordinated downstreams, no FIFO, one or more receivers, non specific as to where amplifying, filtering and digitizing is done) A process for sharing one or more DOCSIS compatible receivers among a larger number of DOCSIS upstream logical channels, comprising the steps:

defining a plurality of DOCSIS upstream logical channels;

performing DOCSIS training and registration of a plurality of cable modems and receiving upstream bandwidth requests therefrom;

allocating bandwidth on each upstream logical channel in a DOCSIS MAP message and coordinating said MAP messages for each upstream logical channel so as to not overflow capacity of one or more receivers which will process DOCSIS data bursts;

if more than one DOCSIS compatible receiver is available to process DOCSIS data bursts, deciding which receiver will process which burst and sending all necessary information to said receiver to configure it to process the assigned burst;

controlling a switch to couple selected bursts arriving at a plurality of inputs of a crossbar switch or multiplexer to one or more selected outputs so as to prevent noise aggregation;

amplifying, filtering and digitizing each said burst signal to provide a plurality of samples, and processing said samples of each said DOCSIS burst to recover the data therefrom.

29. (FIG. 5, means plus function tuners) An upstream line card for a DOCSIS cable modem termination system, comprising:

an analog multiplexer having a plurality of inputs for coupling to a plurality of cables from one or more hybrid fiber coaxial cable DOCSIS data delivery systems, and having a plurality of outputs, and having a control input;

control means coupled to said control input for controlling switching by said analog multiplexer;

a plurality of RF channel means, each coupled to an output of said analog multiplexer, for receiving burst assignment data, MAP data and UCD data and for tuning to the appropriate logical channel at the appropriate time, receiving an assigned burst signal, mixing it down to baseband, converting it to digital samples and storing said samples in a buffer and providing said samples at an output;

a plurality of DOCSIS compatible PHY receiver means each having an input for receiving sample data, for processing said sample data to retrieve data encoded in DOCSIS bursts;

an arbiter means having a plurality of inputs, each input coupled to an output of one of said RF channel means and having a port coupled to receive data from a media access control process and coupled to supply burst assignment data to said RF channel means and said control means, and having a plurality of outputs, each coupled to an input of one of said PHY receiver means, for determining which of said plurality of PHY receivers is to process each DOCSIS burst arriving at said analog multiplexer and sending burst assignment data and DOCSIS UCD data to said PHY receivers; and

a media access control process means coupled to receive data recovered from DOCSIS bursts by said PHY receivers, for implementing DOCSIS protocols and for receiving upstream bandwidth requests and for generating UCD and MAP messages and supplying said MAP data and/or UCD data to said RF channel means and said control means and said arbiter means.

30. (FIG. 10 no tuners, with FIFOs, rcvrs control switching) A cable modem termination system upstream line card, comprising:

a plurality of radio frequency amplifier means, each coupled to receive upstream radio frequency signals from a hybrid fiber coaxial cable system and each for amplifying received radio frequency signals according to a gain controlled by a signal or data received at a gain control input;

a plurality of analog-to-digital converters, each for sampling at a high enough rate to satisfy the Nyquist criteria for the highest frequency signal which might be coupled to an input of said converter;

a crossbar switch having a plurality of inputs, each coupled to a signal output of one of said radio frequency amplifier means, and having a plurality of outputs, each output coupled to an input of one of said analog-to-digital converters, and having a switching control input for each said output;

a plurality of sample storage FIFOs, each coupled by first data path means to a sample output of one of said analog-to-digital converters, said first data path means for conveying data from a sample output of each analog-to-digital converter to an input of a FIFO dedicated to storing samples from said analog-to-digital converter;

one or more PHY receivers, each coupled by second data path means to an output of one of said plurality of FIFOs, and each having a switching control output coupled to one of said switching control inputs of said digital crossbar switch, and each capable of generating from data received from a UMAC process control signals to control coupling of inputs of said crossbar switch to an output of said crossbar switch coupled to said PHY receiver, and each said PHY receiver having a plurality of gain control outputs, each coupled to a gain control input of one of said radio frequency amplifier means, each PHY receiver capable of generating gain control signals at said gain control outputs, each PHY receiver capable of processing digital samples received from one of said FIFOs to extract data transmitted in a burst on a selected upstream channel and presenting said data at a recovered data output;

a plurality of recovered data storage FIFOs, each having an input coupled by third data path means to a recovered data output of one of said PHY receivers, and each having an output;

an arbiter coupled to said PHY receivers for determining which PHY receiver is to receive each burst and for sending messages to each PHY receiver assigning particular bursts said PHY receiver is to receive and supplying necessary UCD and MAP data to said PHY receiver; and

upstream media access control means coupled said outputs of said data storage FIFOs to receive recovered data stored therein and for carrying out all necessary messaging to implement DOCSIS training and registration protocols and for processing recovered data and for defining and assigning channel parameters to each upstream logical channel via a separate upstream channel descriptor message for each said upstream logical channel and for receiving upstream bandwidth requests from each cable modem which has successfully completed training and registered and for making bandwidth grants for each upstream logical channel via downstream MAP messages and for supplying said UCD and MAP data to said arbiter.

31. (FIG. 1 no analog RF tuner) A linecard apparatus with a shared upstream DOCSIS receiver and no DOCSIS transmitter, comprising:

an analog crossbar switch having inputs for coupled to each of a plurality of different optical nodes and having a plurality of outputs and having a control input and functioning to connect the signals at selected inputs to selected outputs at selected time according to said control signals;

a plurality of RF means, each having an RF input coupled to an output of said crossbar switch, each said RF means for amplifying radio frequency (RF) signals appearing at said RF input in a wide band amplifier, said amplification being by a gain established by a gain control signal appearing at a gain control input and for digitizing said amplified RF signals to generate a plurality of samples and storing said samples in a buffer;

one or more DOCSIS compatible receivers to be shared to process samples of RF signals containing DOCSIS upstream bursts and recover the data therefrom, each receiver having an input;

an arbiter having a plurality of inputs, each input coupled to receive samples from a buffer in one of said plurality of RF means, and having one or more outputs, each output coupled to an input of one of said one or more DOCSIS compatible receivers, said arbiter functioning to determine which buffer is to supply its samples to the input of which receiver and making the proper connections and processing to supply said samples to said input of said DOCSIS compatible receiver;

a media access control (MAC) means coupled to receive data recovered by said one or more DOCSIS compatible receivers and to generate DOCSIS UCD and MAP messages and carry out DOCSIS protocols, said MAP messages for transmission on downstreams coupled to cable modems coupled to optical nodes which are coupled to inputs of said crossbar switch (hereafter the upstream group), said MAP messages being generated by said MAC means such that bursts are scheduled in said upstream group such that there are never more overlapping bursts (bursts which overlap in time but which are transmitted upstream from different optical nodes in said upstream group) than there are RF means to receive, digitize and buffer them.

32. (FIG. 5, no arbiter) A linecard apparatus with a shared upstream DOCSIS receiver and no DOCSIS transmitter, comprising:

an analog crossbar switch having inputs for coupled to each of a plurality of different optical nodes and having a plurality of outputs and having a control input and functioning to connect the signals at selected inputs to selected outputs at selected time according to said control signals;

two or more RF means, each having an RF input coupled to an output of said crossbar switch, each said RF means for amplifying radio frequency (RF) signals appearing at said RF input in a wide band amplifier, said amplification being by a gain established by a gain control signal appearing at a gain control input and for digitizing said amplified RF signals to generate a plurality of samples and storing said samples in a buffer;

two or more DOCSIS compatible receivers, where the number of receivers equals the number of RF means, said receivers to be shared to process samples of RF signals containing DOCSIS upstream bursts and recover the data therefrom, each receiver having an input coupled to an output of a sample buffer in one of said two or more RF means, each receiver having an input to receive MAP data and an output at which it generates control signals to control switching by said crossbar switch such that bursts said receiver arriving on inputs of said crossbar switch are coupled at the right time to an output of said crossbar switch to which said receiver is coupled through one of said RF means;

a media access control (MAC) means coupled to receive data recovered by said one or more DOCSIS compatible receivers and to generate DOCSIS UCD and MAP messages and carry out DOCSIS protocols, said MAP messages for transmission on downstreams coupled to cable modems coupled to optical nodes which are coupled to inputs of said crossbar switch (hereafter the upstream group), said MAP messages being generated by said MAC means such that bursts are scheduled in said upstream group such that there are never more overlapping bursts (bursts which overlap in time but which are transmitted upstream from different optical nodes in said upstream group) than there are RF means to receive, digitize and buffer them.

33. (Analog means plus function—

catchall embodiments) A linecard apparatus with a shared upstream DOCSIS receiver and no DOCSIS transmitter, comprising;

switching means for selecting one or more input cable for coupling to one or more switch outputs so as to avoid noise aggregation when processing upstream DOCSIS bursts from multiple optical nodes in a shared upstream DOCSIS receiver;

one or more RF channel means, each coupled to one of said switch outputs and each for receiving and digitizing radio frequency signals;

one or more shared DOCSIS receiver means, each coupled to an output of said RF channel means, for recovering data in upstream DOCSIS bursts;

MAC process means for receiving and processing recovered data, and for generating DOCSIS UCD and MAP data in a coordinated fashion such that said switching means can be controlled to avoid noise aggregation.