Distributed control in a communication system

• US 6,366,585 B1
• Filed: 09/15/1999
• Issued: 04/02/2002
• Est. Priority Date: 02/06/1995
• Status: Expired due to Term

• Current Assignee: HTC Corporation
• Original Assignee: ADC Telecommunications Incorporated (TE Connectivity Limited)
• Inventors: Dapper, Mark J., Geile, Michael J., Hill, Terrance
• Primary Examiner(s): CUMMING, WILLIAM D
• Application Number:
  US09/396,306
• Time in Patent Office: 930 Days
• Field of Search: 370/409, 370/453, 370/479, 370/395, 455/562
• US Class Current: 370/409
• CPC Class Codes: G06F 17/14 Fourier, Walsh or analogous domain transformations , e.g. Laplace, Hilbert, Karhunen-Loeve, transforms for correlation function computation G06F17/156; spectrum analysers G01R23/16
• CPC Class Codes: G06F 17/142 Fast Fourier transforms, e.g. using a Cooley-Tukey type algorithm
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/356 Unequal error protection [UEP]
• CPC Class Codes: H04B 10/272 Star-type networks or tree-type networks
• CPC Class Codes: H04H 20/69 Optical systems
• CPC Class Codes: H04H 20/77 using carrier waves
• CPC Class Codes: H04H 20/78 CATV [Community Antenna Television] systems
• CPC Class Codes: H04H 20/79 using downlink of the CATV systems, e.g. audio broadcast via CATV network
• CPC Class Codes: H04H 20/80 having frequencies in two or more frequency bands, e.g. medium wave and VHF
• CPC Class Codes: H04H 60/11 Arrangements for counter-measures when a portion of broadcast information is unavailable
• CPC Class Codes: H04H 60/86 accessed over CATV networks
• CPC Class Codes: H04H 60/96 CATV systems for accessing the Internet H04H60/86
• CPC Class Codes: H04H 60/97 using uplink of the CATV systems
• CPC Class Codes: H04J 14/0298 with sub-carrier multiplexing [SCM]
• CPC Class Codes: H04J 3/14 Monitoring arrangements for SDH/SONET rings H04J3/085
• CPC Class Codes: H04K 1/00 Secret communication
• CPC Class Codes: H04K 3/226 Selection of non-jammed channel for communication spectrum sharing arrangements H04W16/14; selection of wireless resources by user or terminal H04W72/02
• CPC Class Codes: H04K 3/255 based on redundancy of transmitted data, transmission path or transmitting source
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/0045 : Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 : Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 1/0071 : Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/24 : Testing correct operation
• CPC Class Codes: H04L 12/10 : Current supply arrangements
• CPC Class Codes: H04L 12/12 : Arrangements for remote connection or disconnection of substations or of equipment thereof
• CPC Class Codes: H04L 12/2801 : Broadband local area networks
• CPC Class Codes: H04L 12/44 : Star or tree networks
• CPC Class Codes: H04L 2001/0093 : Point-to-multipoint
• CPC Class Codes: H04L 2027/0036 : using a recovered symbol clock
• CPC Class Codes: H04L 2027/0057 : quadrature phase
• CPC Class Codes: H04L 2027/0067 : Phase error detectors
• CPC Class Codes: H04L 25/03866 : using scrambling
• CPC Class Codes: H04L 27/2601 : Multicarrier modulation systems
• CPC Class Codes: H04L 27/2614 : Peak power aspects
• CPC Class Codes: H04L 27/2631 : with polyphase implementation
• CPC Class Codes: H04L 27/2634 : Inverse fast Fourier transform [IFFT] or inverse discrete Fourier transform [IDFT] modulators in combination with other circuits for modulation
• CPC Class Codes: H04L 27/2647 : Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/2652 : with polyphase implementation
• CPC Class Codes: H04L 27/26524 : Fast Fourier transform [FFT] or discrete Fourier transform [DFT] demodulators in combination with other circuits for demodulation
• CPC Class Codes: H04L 27/2654 : Filtering per subcarrier, e.g. filterbank multicarrier [FBMC]
• CPC Class Codes: H04L 27/2655 : Synchronisation arrangements
• CPC Class Codes: H04L 27/2657 : Carrier synchronisation
• CPC Class Codes: H04L 27/2662 : Symbol synchronisation
• CPC Class Codes: H04L 27/34 : Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• CPC Class Codes: H04L 41/0213 : Standardised network management protocols, e.g. simple network management protocol [SNMP]
• CPC Class Codes: H04L 41/064 : involving time analysis
• CPC Class Codes: H04L 41/0896 : Bandwidth or capacity management, i.e. automatically increasing or decreasing capacities flow or congestion control using dynamic resource allocation, e.g. in-call renegotiation, H04L47/76
• CPC Class Codes: H04L 43/00 : Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/022 : by sampling
• CPC Class Codes: H04L 43/067 : using time frame reporting
• CPC Class Codes: H04L 43/0811 : by checking connectivity
• CPC Class Codes: H04L 43/0817 : by checking functioning
• CPC Class Codes: H04L 43/0823 : Errors, e.g. transmission errors
• CPC Class Codes: H04L 43/0829 : Packet loss
• CPC Class Codes: H04L 43/0847 : Transmission error
• CPC Class Codes: H04L 43/0852 : Delays
• CPC Class Codes: H04L 43/0858 : One way delays
• CPC Class Codes: H04L 43/0864 : Round trip delays
• CPC Class Codes: H04L 43/0882 : Utilisation of link capacity
• CPC Class Codes: H04L 43/16 : Threshold monitoring
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0037 : Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0044 : allocation of payload
• CPC Class Codes: H04L 5/023 : Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/14 : Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/143 : for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04L 5/1484 : operating bytewise
• CPC Class Codes: H04M 7/006 : Networks other than PSTN/ISDN providing telephone service, e.g. Voice over Internet Protocol (VoIP) , including next generation networks with a packet-switched transport layer H04L65/00 takes precedence; aspects not specific to the type of network H04M3/00; special services in those networks H04M3/42
• CPC Class Codes: H04M 9/027 : Frequency division multiplex systems
• CPC Class Codes: H04N 21/2221 : being a cable television head-end CATV in broadcast systems H04H20/78
• CPC Class Codes: H04N 21/2383 : Channel coding or modulation of digital bit-stream, e.g. QPSK modulation arrangements for detecting or preventing errors in the information received by adapting the channel coding H04L1/0009; analogue front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/2385 : Channel allocation H04N21/266 takes precedence; Bandwidth allocation H04N21/24 takes precedence ; allocation of channels according to the instantaneous demands of the users in time-division multiplex systems H04J3/1682; admission control, resource allocation in open networks H04L12/5692; arrangements for maintenance or administration in data switching networks involving bandwidth and capacity management H04L41/0896; negotiating bandwidth in wireless networks H04W28/16
• CPC Class Codes: H04N 21/2402 : Monitoring of the downstream path of the transmission network, e.g. bandwidth available traffic monitoring in data switching networks H04L43/00; monitoring data switching networks utilization H04L43/0876
• CPC Class Codes: H04N 21/4382 : Demodulation or channel decoding, e.g. QPSK demodulation analog front ends or means for connecting modulators, demodulators or transceivers to a transmission line H04L27/0002
• CPC Class Codes: H04N 21/6118 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 21/6137 : involving transmission via a telephone network, e.g. POTS
• CPC Class Codes: H04N 21/6168 : involving cable transmission, e.g. using a cable modem
• CPC Class Codes: H04N 7/17309 : Transmission or handling of upstream communications
• CPC Class Codes: H04N 7/22 : Adaptations for optical transmission
• CPC Class Codes: H04W 24/00 : Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 24/08 : Testing, supervising or monitoring using real traffic
• CPC Class Codes: Y02D 30/50 : in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A communication system is described. The communication system includes a distribution network and a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network. In addition the communication system includes a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth. The head end terminal includes a detector that detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal. Each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit.

Claims

1. A multi-point to point communication system, comprising:

a distribution network;

a head end terminal for downstream transmission of downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and for receipt of upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network, the head end terminal including;

head end multicarrier modem means for modulating at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and for demodulating at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth;

head end controller means operatively connected to the head end multicarrier modem means for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information;

a plurality of service units, each service unit associated with at least one remote unit and operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth, each service unit including;

service unit multicarrier modem means for modulating at least upstream telephony information on at least one carrier orthogonal at the head end terminal to at least one other carrier in the second frequency bandwidth and for demodulating at least downstream telephony information modulated on a plurality of orthogonal carriers in the first frequency bandwidth;

service unit controller means operatively connected to the service unit multicarrier modem means for controlling the modulation and demodulation performed by the service unit multicarrier modem means, the service unit controller means for adjusting at least one local transmission characteristic in response to an adjustment command from the head end controller means transmitted in the downstream control data to the at least one remote unit;

the head end controller means further including;

detection means for detecting the at least one local transmission characteristic of the service unit multicarrier modem means associated with the at least one remote unit and for generating the adjustment command as a function of the detected at least one local transmission characteristic for transmittal to the service unit multicarrier modem means associated with the at least one remote unit in the downstream control data.

2. The system according to claim 1, wherein the at least one local transmission characteristic includes symbol timing.

3. The system to claim 2,

wherein the detection means further includes means for detecting symbol timing of data transmitted by the service unit associated with the at least one remote unit in response to a command from the head end controller means,

wherein the detection means includes means for generating a symbol timing error,

wherein the head end controller means includes means for generating a symbol timing adjustment command based on the symbol timing error for transmission to the service unit associated with the at least one remote unit in the downstream control data, and

wherein the service unit controller means includes means for adjusting symbol timing in response to the symbol timing adjustment command.

4. The system according to claim 1, wherein the at least one local transmission characteristic includes transmission frequency.

5. The system according to claim 4,

wherein the detection means further includes means for detecting the transmission frequency of the service unit associated with the at least one remote unit in response to a command from the head end controller means,

wherein the detection means includes means for generating a transmission frequency error,

wherein the head end controller means includes means for generating a transmission frequency adjustment command based on the transmission frequency error for transmission to the service unit associated with the at least one remote unit in the downstream control data, and

wherein the service unit controller means includes means for adjusting the transmission frequency in response to the transmission frequency adjustment command.

6. The system according to claim 1, wherein the transmission characteristic includes amplitude.

7. The system according to claim 6,

wherein the detection means further includes means for detecting amplitude of transmission by the service unit associated with the at least one remote unit in response to a command from the head end controller means,

wherein the detection means includes means for generating an amplitude error,

wherein the head end controller means includes means for generating an amplitude adjustment command based on the amplitude error for transmission to the service unit associated with the at least one remote unit in the downstream control data, and

wherein the service unit controller means includes means for adjusting amplitude of transmission in response to the amplitude adjustment command.

8. The system according to claim 1, wherein the at least one local transmission characteristic includes transmission frequency and symbol timing.

9. The system according to claim 8, wherein the at least one local transmission characteristic further includes amplitude of transmission.

10. The system of claim 1, wherein the distribution network is a hybrid fiber/coax distribution network.

11. The system according to claim 1, wherein the plurality of orthogonal carriers in the first frequency bandwidth include a plurality of telephony information channels for transmission of downstream telephony information after modulation of downstream telephony information thereon and at least one control channel for transmission of downstream control data after modulation of downstream control data thereon;

further wherein the plurality of orthogonal carriers in the second frequency bandwidth include a plurality of telephony information channels for transmission of upstream telephony information after modulation of upstream telephony information thereon and at least one control channel for transmission of upstream control data after modulation of upstream control data thereon.

12. The system according to claim 11, wherein the at least one control channel for transmission of upstream control data in the second frequency bandwidth is differentially modulated.

13. The system according to claim 11, wherein the at least one control channel of the first frequency bandwidth and the at least one control channel of the second frequency bandwidth each include at least one synchronization channel in the respective frequency bandwidth.

14. The system according to claim 13, wherein the at least one control channel of the first frequency bandwidth and the at least one control channel of the second frequency bandwidth each include redundant synchronization channels.

15. The system according to claim 13, wherein each at least one synchronization channel is offset from the telephony information channels of the respective frequency bandwidth.

16. The system according to claim 14, wherein the at least one synchronization channel is operated at a lower transmission level relative to the telephony information channels to reduce the amount of offset.

17. The system according to claim 15, wherein the at least one control channel of the first frequency bandwidth and the at least one control channel of the second frequency bandwidth each include redundant synchronization channels offset from the telephony information channels in the respective frequency bandwidths.

18. The system according to claim 11, wherein a first modulation technique of a plurality of modulation techniques is utilized for modulation of at least one channel in the first frequency bandwidth and the second frequency bandwidth and wherein at least one other modulation technique of the plurality of modulation techniques is utilized for modulation of at least one other channel in the first frequency bandwidth and the second frequency bandwidth.

19. The system of claim 18, wherein the first modulation technique is utilized for modulation of the control data on the at least one control channel and the at least one other modulation technique is utilized for modulation of the telephony information on the telephony information channels.

20. The system according to claim 18, wherein the first modulation technique includes a lower order modulation with fewer bits/symbol relative to the at least one other modulation technique.

21. The system according to claim 18, wherein the first modulation technique is utilized for modulation of at least downstream telephony information on the at least one telephony channel in the first frequency bandwidth and the at least on other modulation technique is utilized for modulation of at least upstream telephony information on at least one telephony information channel in the second frequency bandwidth, the first modulation technique being a higher order modulation technique with more bits/symbol relative to the at least one other modulation technique.

22. The system according to claim 11, wherein the head end controller means includes means for initiating synchronization periodically by an inactive but allocated service unit associated with at least one remote unit over at least one control channel.

23. The system according to claim 11, wherein the head end controller means includes means for periodically requesting over the at least one control channel in the first frequency bandwidth an upstream signal to be transmitted by the service unit modem means associated with at least one remote unit and means for detecting the upstream signal transmitted over a control channel in the second frequency bandwidth to verify that the upstream signal from the remote unit is within tolerance required to establish communication between the head end terminal and the remote unit.

24. A communication system, comprising:

a distribution network;

a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network, wherein the head end terminal includes a head end multicarrier modem that modulates downstream telephony information on a first plurality of orthogonal carriers and demodulates upstream telephony information modulated on a second plurality of orthogonal carriers;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein each service unit includes a service unit multicarrier modem adapted to modulate upstream telephony information on at least one carrier orthogonal at the head end terminal to at least one other carrier in the second frequency bandwidth and demodulate downstream telephony information modulated on a plurality of orthogonal carriers in the first frequency bandwidth;

wherein each service unit further includes a service unit controller operatively connected to the service unit multicarrier modem, wherein the service unit controller controls the modulation and demodulation performed by the service unit multicarrier modem and adjusts at least one local transmission characteristic in response to an adjustment command from the head end controller transmitted in downstream control data to the service unit; and

wherein the head end terminal further includes a detector that detects the at least one local transmission characteristic and generates the adjustment command as a function of the detected at least one local transmission characteristic for transmittal to the service unit multicarrier modem in the downstream control data.

25. The system of claim 24, wherein the head end terminal further includes a head end controller operatively connected to the head end multicarrier modem.

26. The system of claim 25, wherein the head end controller controls transmission of the downstream telephony information and downstream control data and controls receipt of the upstream control data and upstream telephony information.

27. The system of claim 24, wherein the at least one local transmission characteristic includes symbol timing.

28. The system of claim 27, wherein the detector detects symbol timing of data transmitted by the service unit in response to a command from the head end controller.

29. The system of claim 28, wherein the detector generates a symbol timing error, the head end controller generates a symbol timing adjustment command based on the symbol timing error for transmission to the service unit in the downstream control data, and the service unit controller adjusts symbol timing in response to the symbol timing adjustment command.

30. The system of claim 24, wherein the at least one local transmission characteristic includes transmission frequency.

31. The system of claim 25, wherein the detector further detects the transmission frequency of the service unit in response to a command from the head end controller and generates a transmission frequency error, wherein the head end controller generates a transmission frequency adjustment command based on the transmission frequency error for transmission to the service unit in the downstream control data, and wherein the service unit controller adjusts the transmission frequency in response to the transmission frequency adjustment command.

32. The system of claim 24, wherein the transmission characteristic includes amplitude.

33. The system of claim 32, wherein the detector detects the amplitude of transmission by the service unit in response to a command from the head end controller and generates an amplitude error, wherein the head end controller generates an amplitude adjustment command based on the amplitude error for transmission to the service unit in the downstream control data, and wherein the service unit controller adjusts amplitude of transmission in response to the amplitude adjustment command.

34. The system of claim 24, wherein the distribution network is a hybrid fiber/coax distribution network.

35. The system of claim 24, wherein the plurality of orthogonal carriers in the first frequency bandwidth include a plurality of telephony information channels for transmission of downstream telephony information after modulation of downstream telephony thereon and at least one control channel for transmission of downstream control data after modulation of downstream control data thereon.

36. The system of claim 35, wherein the plurality of orthogonal carriers in the second frequency bandwidth include a plurality of telephony information channels for transmission of upstream telephony information after modulation of upstream telephony information thereon and at least one control channel for transmission of upstream control data after modulation of upstream control data thereon.

37. The system of claim 36, wherein the at least one control channel for transmission of upstream control data in the second frequency bandwidth is differentially modulated.

38. The system of claim 36, wherein the head end controller periodically requests over the at least one control channel in the first frequency bandwidth an upstream signal to be transmitted by the service unit and detects the upstream signal transmitted over a control channel in the second frequency bandwidth to verify that the upstream signal from the service unit is within tolerance required to establish communication between the head end terminal and the service unit.

39. A communication system, comprising:

a distribution network;

a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth, wherein the service unit includes a service unit multicarrier modem adapted to modulate at least upstream telephony information on at least one carrier orthogonal at the head end terminal to at least one other carrier in the second frequency bandwidth and demodulate at least downstream telephony information modulated on a plurality of orthogonal carriers in the first frequency bandwidth; and

wherein the head end terminal includes a detector that detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal; and

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit.

40. The system of claim 39, wherein the service unit further includes a service unit controller operatively connected to the service unit multicarrier modem for controlling the modulation and demodulation performed by the service unit multicarrier modem, the service unit controller for adjusting the at least one local transmission characteristic in response to the adjustment command.

41. A communication system, comprising:

a distribution network;

a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein the head end terminal includes a detector that detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal;

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit;

wherein the head end terminal includes a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth;

wherein the head end terminal further includes a head end controller operatively connected to the head end multicarrier modem for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information; and

wherein the at least one local transmission characteristic includes symbol timing.

42. The system of claim 41, wherein the detector is adapted to detect symbol timing of data transmitted by the service unit in response to a command from the head end controller.

43. The system of claim 42, wherein the detector generates a symbol timing error, the head end controller generates a symbol timing adjustment command based on the symbol timing error for transmission to the service unit in the downstream control data, and the service unit controller adjusts symbol timing in response to the symbol timing adjustment command.

44. A communication system, comprising:

a distribution network;

a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein the head end terminal includes a detector that detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal;

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit;

wherein the head end terminal includes a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth;

wherein the head end terminal further includes a head end controller operatively connected to the head end multicarrier modem for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information; and

wherein the at least one local transmission characteristic includes transmission frequency.

45. The system of claim 44, wherein the detector detects the transmission frequency of the service unit in response to a command from the head end controller and generates a transmission frequency error, wherein the head end controller generates a transmission frequency adjustment command based on the transmission frequency error for transmission to the service unit in the downstream control data, and wherein the service unit controller adjusts the transmission frequency in response to the transmission frequency adjustment command.

46. A communication system, comprising:

a distribution network;

a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein the head end terminal includes a detector that detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal;

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit;

wherein the head end terminal includes a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth;

wherein the head end terminal further includes a head end controller operatively connected to the head end multicarrier modem for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information; and

wherein the transmission characteristic includes amplitude.

47. The system of claim 46, wherein the detector detects the amplitude of transmission by the service unit in response to a command from the head end controller and generates an amplitude error, wherein the head end controller generates an amplitude adjustment command based on the amplitude error for transmission to the service unit in the downstream control data, and wherein the service unit controller adjusts amplitude of transmission in response to the amplitude adjustment command.

48. A communication system, comprising:

a distribution network;

a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein the head end terminal includes a detector that detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal; and

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit;

wherein the head end terminal includes a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth;

wherein the head end terminal further includes a head end controller operatively connected to the head end multicarrier modem for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information; and

wherein the at least one local transmission characteristic includes transmission frequency and symbol timing.

49. The system of claim 48, wherein the at least one local transmission characteristic further includes amplitude of transmission.

50. A communication system, comprising:

a distribution network;

a head end terminal adapted to transmit downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and adapted to receive upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein the head end terminal includes a detector that detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal; and

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit;

wherein the head end terminal includes a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth; and

wherein the plurality of orthogonal carriers in the first frequency bandwidth include a plurality of telephony information channels for transmission of downstream telephony information after modulation of downstream telephony thereon and at least one control channel for transmission of downstream control data after modulation of downstream control data thereon.

51. The system of claim 50, wherein the plurality of orthogonal carriers in the second frequency bandwidth include a plurality of telephony information channels for transmission of upstream telephony information after modulation of upstream telephony information thereon and at least one control channel for transmission of upstream control data after modulation of upstream control data thereon.

52. The system of claim 51, wherein the head end terminal is adapted for initiating synchronization periodically by an inactive but allocated service unit over at least one control channel.

53. The system of claim 51, wherein the head end terminal is adapted for periodically requesting over the at least one control channel in the first frequency bandwidth an upstream signal to be transmitted by the service unit and adapted for detecting the upstream signal transmitted over a control channel in the second frequency bandwidth to verify that the upstream signal from the service unit is within tolerance required to establish communication between the head end terminal and the service unit.

54. A communication system, comprising:

a hybrid fiber/coax distribution network;

a head end terminal for downstream transmission of downstream control data and downstream telephony information in a first frequency bandwidth over the hybrid distribution network and for receipt of upstream telephony information and upstream control data in a second frequency bandwidth over the hybrid distribution network, the head end terminal including;

a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth;

a head end controller operatively connected to the head end multicarrier modem for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information;

wherein the plurality of orthogonal carriers in the first frequency bandwidth include a plurality of telephony information channels for transmission of downstream telephony information and at least one control channel for transmission of downstream control data; and

wherein the plurality of orthogonal carriers in the second frequency bandwidth include a plurality of telephony information channels for transmission of upstream telephony information and at least one control channel for transmission of upstream control data;

a plurality of service units, each service unit operatively connected to the hybrid distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth, each service unit including;

a service unit multicarrier modem adapted to modulate at least upstream telephony information on at least one carrier orthogonal at the head end terminal to at least one other carrier in the second frequency bandwidth and demodulate at least downstream telephony information modulated on a plurality of orthogonal carriers in the first frequency bandwidth; and

a service unit controller operatively connected to the service unit multicarrier modem for controlling the modulation and demodulation performed by the service unit multicarrier modem, the service unit controller for adjusting at least one local transmission characteristic in response to an adjustment command from the head end controller transmitted in the downstream control data to the service unit;

wherein the head end controller includes;

a detector for detecting the at least one local transmission characteristic of the service unit multicarrier modem and for generating the adjustment command as a function of the detected at least one local transmission characteristic for transmittal to the service unit multicarrier modem in the downstream control data; and

wherein a first modulation technique of a plurality of modulation techniques is utilized for modulation of at least one channel in the first frequency bandwidth and the second frequency bandwidth and wherein at least one other modulation technique of the plurality of modulation techniques is utilized for modulation of at least one other channel in the first frequency bandwidth and the second frequency bandwidth.

55. The system of claim 54, wherein the first modulation technique is utilized for modulation of at least downstream telephony information on the at least one telephony channel in the first frequency bandwidth and the at least one other modulation technique is utilized for modulation of at least upstream telephony information on at least one telephony information channel in the second frequency bandwidth, the first modulation technique being a higher order modulation technique with more bits/symbol relative to the at least one other modulation technique.

56. The system of claim 54, wherein the first modulation technique is utilized for modulation of the control data on the at least one control channel and the at least one other modulation technique is utilized for modulation of the telephony information on the telephony information channels.

57. The system of claim 54, wherein the first modulation technique includes a lower order modulation with fewer bits/symbol relative to the at least one other modulation technique.

58. A communication system, comprising:

a hybrid fiber/coax distribution network;

a head end terminal for downstream transmission of downstream control data and downstream telephony information in a first frequency bandwidth over the hybrid distribution network and for receipt of upstream telephony information and upstream control data in a second frequency bandwidth over the hybrid distribution network, the head end terminal including;

a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth;

a head end controller operatively connected to the head end multicarrier modem for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information;

wherein the plurality of orthogonal carriers in the first frequency bandwidth include a plurality of telephony information channels for transmission of downstream telephony information and at least one control channel for transmission of downstream control data; and

wherein the plurality of orthogonal carriers in the second frequency bandwidth include a plurality of telephony information channels for transmission of upstream telephony information and at least one control channel for transmission of upstream control data;

a plurality of service units, each service unit operatively connected to the hybrid distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth, each service unit including;

a service unit multicarrier modem adapted to modulate at least upstream telephony information on at least one carrier orthogonal at the head end terminal to at least one other carrier in the second frequency bandwidth and demodulate at least downstream telephony information modulated on a plurality of orthogonal carriers in the first frequency bandwidth; and

a service unit controller operatively connected to the service unit multicarrier modem for controlling the modulation and demodulation performed by the service unit multicarrier modem, the service unit controller for adjusting at least one local transmission characteristic in response to an adjustment command from the head end controller transmitted in the downstream control data to the service unit;

wherein the head end controller includes;

a detector for detecting the at least one local transmission characteristic of the service unit multicarrier modem and for generating the adjustment command as a function of the detected at least one local transmission characteristic for transmittal to the service unit multicarrier modem in the downstream control data; and

wherein the at least one control channel for transmission of upstream control data in the second frequency bandwidth is differentially modulated.

59. A communication system, comprising:

a distribution network;

a head end terminal that transmits downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and receives upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein the head end terminal includes a detector that monitors the upstream control data during initialization and operation and detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal;

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit;

wherein the head end terminal includes a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth; and

wherein the head end terminal further includes a head end controller operatively connected to the head end multicarrier modem for controlling transmission of the downstream telephony information and downstream control data and for controlling receipt of the upstream control data and upstream telephony information.

60. The system of claim 59, wherein the service unit includes a service unit multicarrier modem adapted to modulate at least upstream telephony information on at least one carrier orthogonal at the head end terminal to at least one other carrier in the second frequency bandwidth and demodulate at least downstream telephony information modulated on a plurality of orthogonal carriers in the first frequency bandwidth.

61. The system of claim 60, wherein the service unit further includes a service unit controller operatively connected to the service unit multicarrier modem for controlling the modulation and demodulation performed by the service unit multicarrier modem, the service unit controller for adjusting the at least one local transmission characteristic in response to the adjustment command.

62. The system of claim 59, wherein the at least one local transmission characteristic includes symbol timing.

63. The system of claim 62, wherein the detector is adapted to detect symbol timing of data transmitted by the service unit in response to a command from the head end controller.

64. The system of claim 63, wherein the detector generates a symbol timing error, the head end controller generates a symbol timing adjustment command based on the symbol timing error for transmission to the service unit in the downstream control data, and the service unit controller adjusts symbol timing in response to the symbol timing adjustment command.

65. The system of claim 59, wherein the at least one local transmission characteristic includes transmission frequency.

66. The system of claim 65, wherein the detector detects the transmission frequency of the service unit in response to a command from the head end controller and generates a transmission frequency error, wherein the head end controller generates a transmission frequency adjustment command based on the transmission frequency error for transmission to the service unit in the downstream control data, and wherein the service unit controller adjusts the transmission frequency in response to the transmission frequency adjustment command.

67. The system of claim 59, wherein the transmission characteristic includes amplitude.

68. The system of claim 67, wherein the detector detects the amplitude of transmission by the service unit in response to a command from the head end controller and generates an amplitude error, wherein the head end controller generates an amplitude adjustment command based on the amplitude error for transmission to the service unit in the downstream control data, and wherein the service unit controller adjusts amplitude of transmission in response to the amplitude adjustment command.

69. The system of claim 59, wherein the at least one local transmission characteristic includes transmission frequency and symbol timing.

70. The system of claim 69, wherein the at least one local transmission characteristic further includes amplitude of transmission.

71. A communication system, comprising:

a distribution network;

a head end terminal that transmits downstream control data and downstream telephony information in a first frequency bandwidth over the distribution network and receives upstream telephony information and upstream control data in a second frequency bandwidth over the distribution network;

a plurality of service units, each service unit operatively connected to the distribution network for upstream transmission of upstream telephony information and upstream control data in the second frequency bandwidth and for receipt of downstream control data and downstream telephony information in the first frequency bandwidth;

wherein the head end terminal includes a detector that monitors the upstream control data during initialization and operation and detects at least one local transmission characteristic of a service unit and generates an adjustment command as a function of the detected at least one local transmission characteristic for transmittal;

wherein each service unit adjusts the at least one local transmission characteristic when an adjustment command is received from the head end terminal in the downstream control data to the service unit;

wherein the head end terminal includes a head end multicarrier modem adapted to modulate at least downstream telephony information on a plurality of orthogonal carriers in the first frequency bandwidth and demodulate at least upstream telephony information modulated on a plurality of orthogonal carriers in the second frequency bandwidth; and

wherein the plurality of orthogonal carriers in the first frequency bandwidth include a plurality of telephony information channels for transmission of downstream telephony information after modulation of downstream telephony thereon and at least one control channel for transmission of downstream control data after modulation of downstream control data thereon.

72. The system of claim 71, wherein the plurality of orthogonal carriers in the second frequency bandwidth include a plurality of telephony information channels for transmission of upstream telephony information after modulation of upstream telephony information thereon and at least one control channel for transmission of upstream control data after modulation of upstream control data thereon.

73. The system of claim 72, wherein the head end terminal is adapted for initiating synchronization periodically by an inactive but allocated service unit over at least one control channel.

74. The system of claim 72, wherein the head end terminal is adapted for periodically requesting over the at least one control channel in the first frequency bandwidth an upstream signal to be transmitted by the service unit and adapted for detecting the upstream signal transmitted over a control channel in the second frequency bandwidth to verify that the upstream signal from the service unit is within tolerance required to establish communication between the head end terminal and the service unit.