Efficient bandwidth utilization methods for CATV DOCSIS channels and other applications

Patent metadata

Field	Value
Publication number	US-9762288-B2
Application number	US-201514806591-A
Country	US
Kind code	B2
Filing date	Jul 22, 2015
Priority date	Apr 10, 2012
Publication date	Sep 12, 2017
Grant date	Sep 12, 2017

Abstract

Methods to improve the data carrying capacity of CATV DOCSIS systems and other communications systems are disclosed. Communications channels may be more efficiently spaced with reduced or absent guard bands by using receivers with adaptive signal cancellation methods, equalizing circuits, or polyphase filter banks and Fast Fourier Transform signal processing methods to correct for higher levels of cross-talk. QAM type communications channels may also be utilized on a synchronized two-transmitter at a time basis by adjusting the transmitters to predefined signal levels, such as +1, −1, +½, −½ to enable the combined signals to be distinguished at the receiver. These two methods may be combined to create a still higher data throughput system.

First claim

The invention claimed is:

1. A method of improving upstream data transmission rate of a Data Over Cable Service Interface Specification (DOCSIS) cable television (CATV) cable system, the method comprising:
directing a plurality of cable modems to transmit upstream data using a plurality of adjacent upstream channels with minimal guard bands, wherein each of the plurality of adjacent upstream channels are separated by a minimal guard band with a bandwidth of less than or equal to one half α*Fs, wherein Fs is the bandwidth of each of the plurality of adjacent upstream channels and α is the roll-off factor of the bandwidth of each of the plurality of adjacent upstream channels;
from the plurality of cable modems, receiving the plurality of adjacent upstream channels separated by the minimal guard bands; and
correcting for cross talk between the received plurality of adjacent upstream channels.

2. The method of claim 1 , wherein N adjacent upstream channels with bandwidth Fs are received from N cable modems, wherein the bandwidth occupied by the N adjacent upstream channels, including roll off at the two extreme boundaries of said N adjacent channels is (N+α)*Fs, where Fs is the bandwidth of each of said channels, and α is the roll-off factor of the bandwidth of the two channels at the two extreme boundaries of said N adjacent channels.

3. The method of claim 1 , wherein correcting for cross talk between the received plurality of adjacent upstream channels comprises using one of an adaptive signal separation method or a signal equalization method.

4. The method of claim 1 , wherein correcting for cross talk between the received plurality of adjacent upstream channels comprises:
partitioning incoming closely spaced channel signals through a polyphase filter bank; and
processing an output from the polyphase filter bank using Fast Fourier Transform methods.

5. The method of claim 1 , wherein directing the plurality of cable modems to transmit upstream data using the plurality of adjacent upstream channels with minimal guard bands comprises transmitting a plurality of DOCSIS Offset Frequency Adjust parameters to the plurality of cable modems.

6. A method of improving the upstream data transmission rate of a Data Over Cable Service Interface Specification (DOCSIS) cable television (CATV) cable system, the method comprising:
directing a plurality of cable modems to transmit upstream data using a plurality of adjacent upstream channels with minimal guard bands;
from the plurality of cable modems, receiving the plurality of adjacent upstream channels separated by the minimal guard bands;
correcting for cross talk between the received plurality of adjacent upstream channels;
directing a first cable modem to upstream transmit a first set of signals using a particular Synchronous Code Division Multiple Access (SCDMA) code at a first range of signal intensity levels at a given time and given frequency;
directing a second cable modem to transmit a second set of signals using the same particular SCDMA code at a second range of signal intensity levels at the same given time and same given frequency;
receiving a combined signal including the first set of signals and the second set of signals; and
separating the first set of signals from the second set of signals.

7. The method of claim 6 , wherein directing the first cable modem to upstream transmit the first set of signals using the particular SCDMA code at the first range of signal intensity levels and directing the second cable modem to upstream transmit the second set of signals using the same particular SCDMA code at the second range of signal intensity levels is done by (i) carrier, clock, and phase synchronizing the first and second cable modems and (ii) transmitting at least one DOCSIS Power Level Adjust or Transmit Equalization Set parameters to the first and second cable modems.

8. The method of claim 6 , wherein the second range of signal intensity levels has a value that is half that of the first range of signal intensity levels.

9. The method of claim 6 , wherein the first cable modem transmits using a same first type of Quadrature Amplitude Modulation (QAM) protocol that is same as the second cable modem, or wherein the first cable modem transmits using a second type of QAM protocol that is different from the second cable modem.

10. Data Over Cable Service Interface Specification (DOCSIS) cable television (CATV) cable system with improved upstream data transmission rate, the system comprising:
a first DOCSIS cable modem that is configured to transmit a first set of upstream signals using a Synchronous Code Division Multiple Access (SCDMA) code at a first range of signal intensity levels at a given time and a given frequency;
a second DOCSIS cable modem that is configured to transmit a second set of upstream signals using the same SCDMA code at a second range of signal intensity levels at the same given time and the same frequency; and
a DOCSIS receiver that is configured to receive a combined signal including the first set of upstream signals and the second set of upstream signals and separate the first set of upstream signals from the second set of upstream signals.

11. The system of claim 10 , wherein the DOCSIS receiver is further configured to direct the first DOCSIS cable modem to transmit the first set of upstream signals at the first range of signal intensity levels and directing the second DOCSIS cable modem to transmit the second set of upstream signals at the second range of signal intensity levels (i) carrier, clock, and phase synchronizing the first and second DOCSIS cable modems and (ii) transmitting at least one DOCSIS Power Level Adjust or Transmit Equalization Set parameters to said first and second DOCSIS cable modems.

12. The system of claim 10 , wherein the second range of signal intensity levels has a value that is half the first range of signal intensity levels.

13. The system of claim 10 , wherein the first DOCSIS cable modem transmits using a first type of Quadrature Amplitude Modulation (QAM) protocol that is same as the second DOCSIS cable modem, or wherein the first DOCSIS cable modem transmits using a second type of QAM protocol that is different from the second DOCSIS cable modem.

14. The system of claim 10 , wherein the first and second DOCSIS cable modems are further configured to transmit the first and second sets of upstream signals using a plurality of adjacent channels with minimal guard bands; and
wherein the DOCSIS receiver is further configured to receive the plurality of adjacent channels and correct for cross talk between the plurality of adjacent channels.

15. The system of claim 14 , wherein each of the plurality of adjacent channels is separated by a minimal guard band with a bandwidth of less than or equal to one half α*Fs, wherein Fs is the bandwidth of each of the plurality of adjacent channels, and α is the roll-off factor of the bandwidth of each of the plurality of adjacent channels.

16. The system of claim 14 , wherein the first and second DOCSIS cable modems transmit N adjacent channels with bandwidth Fs, wherein the bandwidth occupied by the N adjacent channels, including roll off at the two extreme boundaries of the N adjacent channels is (N+α)*Fs, wherein Fs is the bandwidth of each of the N adjacent channels, and α is a roll-off factor of the bandwidth of the two channels at the two extreme boundaries of the N adjacent channels.

17. The system of claim 14 , wherein the DOCSIS receiver corrects for cross-talk between the plurality of adjacent channels using one of an adaptiv

Assignees

• Gainspeed Inc
• Alcatel Lucent Usa Inc

Inventors

• Rakib Shlomo Selim

Classifications

• H04L5/06

  the signals being represented by different frequencies (combined with time-division multiplexing H04L5/26) · CPC title

• H04L5/04

  the signals being represented by different amplitudes or polarities, e.g. quadriplex · CPC title

• H04J1/12

  Arrangements for reducing cross-talk between channels {(in line transmission systems H04B3/32; in cables or lines H04B3/26 - H04B3/30)} · CPC title

• H04B3/32 Primary

  Reducing cross-talk, e.g. by compensating · CPC title

• H04L27/3472

  by switching between alternative constellations · CPC title