Method for reducing interference from initializing network devices in a data-over-cable system

• US 6,940,874 B2
• Filed: 11/30/2000
• Issued: 09/06/2005
• Est. Priority Date: 11/30/2000
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: 3Com Corporation (HP Inc.)
• Inventors: Ruszczyk, Chester A., Willming, David
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Elallam, Ahmed
• Application Number:
  US09/727,069
• Publication Number:
  US 20020101883A1
• Time in Patent Office: 1,741 Days
• Field of Search: 370/252, 370/270, 370/458, 370/461, 370/462, 370/480, 370/486, 370/503, 370/516, 370/210, 370/211, 370/241, 370/241.1, 370/449, 370/485, 725/114, 725/117, 725/144, 725/148, 725/111, 725/116
• US Class Current: 370/516
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04L 27/34 Amplitude- and phase-modulated carrier systems, e.g. quadrature-amplitude modulated carrier systems
• CPC Class Codes: H04L 5/143 for modulated signals H04L5/1469 takes precedence
• CPC Class Codes: H04N 7/17309 Transmission or handling of upstream communications

Abstract

Methods for reducing interference from initializing network devices in a data-over-cable system. The method includes aligning Initial Maintenance intervals for multiple upstream channels of the data-over-cable system. A cable modem termination system determines if usage intervals for the upstream channels may accommodate Initial Maintenance intervals that start at a common time. If so, the cable modem termination system constructs Bandwidth Allocation MAP messages for the usage intervals that contain Initial Maintenance intervals timed to start at the common time. In response to the MAP messages, initializing network devices range when there are no scheduled data transmissions on any upstream channel. The method may shorten a cable modem'"'"'s time for ranging and may decrease collisions with data transmissions on the upstream paths when cable modems try to initialize.

Claims

1. A method for reducing interference from initializing network devices in a data-over-cable system having a plurality of upstream channels, the method comprising:

aligning a plurality of maintenance intervals, wherein each maintenance interval of the plurality of maintenance intervals is associated with a corresponding upstream channel of the plurality of upstream channels;

instructing the initializing network devices to range during the corresponding maintenance intervals of the plurality of maintenance intervals; and

wherein the aligning step comprises the steps of;

determining a measure of common maintenance start time for the plurality of maintenance intervals;

deciding whether the measure of common maintenance start time falls within a plurality of usage intervals, wherein each usage interval of the plurality of usage intervals is associated with an upstream channel of the plurality of upstream channels; and

when the measure of common maintenance start time falls within the plurality of usage intervals, scheduling the plurality of maintenance intervals to start at the measure of common maintenance start time; and

wherein the determining step comprises the steps of;

receiving a measure of present time, T_P;

calculating the measure of common maintenance start time equal to expression T_P+T_B−

T_P mod(T_B), wherein T_B is a measure of a base insertion time for the plurality of maintenance intervals in the data-over-cable system.

2. The method of claim 1, wherein the deciding step comprises the steps of:

receiving a measure of usage interval start time, T_S, for each usage interval of the plurality of usage intervals; and

deciding whether the measure of common maintenance start time, T_M, satisfies expression T_S≦

T_M<

T_S+L, for each usage interval of the plurality of usage intervals, wherein L is a measure of usage interval length for the usage interval.

3. The method of claim 1 wherein the aligning step comprises the steps of:

identifying a longest maintenance interval from the plurality of maintenance intervals; and

calculating a number of maintenance intervals, N, that can occur during the longest maintenance interval for each upstream channel of the plurality of upstream channels.

4. The method of claim 3 wherein the deciding step comprises the steps of:

receiving a measure of usage interval start time, T_S, for each usage interval of the plurality of usage intervals; and

deciding whether the measure of common maintenance start time, T_M, satisfies expression T_S≦

T_M<

T_S+L, for each usage interval of the plurality of usage intervals, wherein L is a measure of usage interval length for the usage interval.

5. The method of claim 3 wherein the scheduling step comprises the steps of:

constructing a plurality of information elements, wherein each information element of plurality of information elements corresponds to a maintenance interval of the plurality of maintenance intervals; and

incorporating each information element of the plurality of information elements into an Upstream Bandwidth Allocation Map message, wherein the Upstream Bandwidth Allocation Map message corresponds to a usage interval of the plurality of usage intervals, and wherein the information element contains an offset corresponding to the measure of common maintenance a start time.

6. The method of claim 3 wherein the plurality of maintenance intervals is a plurality of Initial Maintenance intervals.

7. The method of claim 3 further comprising the step of:

scheduling upstream transmissions within each usage interval of the plurality of intervals before the measure of common maintenance start time.

8. The method of claim 3 further comprising the step of:

scheduling upstream transmissions within each usage interval of the plurality of intervals after the measure of common maintenance start time.

aligning a plurality of maintenance intervals, wherein each maintenance interval of the plurality of maintenance intervals is associated with a corresponding upstream channel of the plurality of upstream channels; and

instructing the initializing network devices to range during the corresponding maintenance interval of the plurality of maintenance intervals.

9. A method for reducing interference from initializing network devices in a data-over-cable system having a plurality of upstream channels, the method comprising:

receiving a measure of present time, T_P;

calculating a measure of common maintenance start time, T_M, equal to expression T_P+T_B−

T_P mod(T_B), wherein T_B is a measure of a base insertion time for a plurality of maintenance intervals in the data-over-cable system;

receiving a measure of usage interval start time, T_S, for each usage interval of a plurality of usage intervals;

deciding whether the measure of common maintenance start time, T_M, satisfies expression T_S≦

T_M<

T_S=L, for each usage interval of the plurality of usage intervals, wherein L is a measure of usage interval length for the usage interval;

when the measure of common maintenance start time, T_M, satisfies expression T_S≦

T_M<

T_P+L, for each usage interval of the plurality of usage intervals, scheduling the plurality of maintenance intervals to start at the measure of common maintenance start time; and

instructing the initializing network devices to range during the plurality of maintenance intervals.

10. A computer readable medium, having stored therein instructions for causing a central processing unit to execute the method of claim 9.

11. A method for reducing interference from initializing network devices in a data-over-cable system having a plurality of upstream channels, the method comprising:

receiving a measure of present time, T_P;

calculating a measure of common maintenance start time, T_M, equal to expression T_P+T_B−

T_P mod(T_B), wherein T_B is a measure of a base insertion time for a plurality of maintenance intervals in the data-over-cable system;

identifying a longest maintenance interval from the plurality of maintenance intervals;

calculating a number of maintenance intervals, N, that can occur during the longest maintenance interval for each upstream channel of the plurality of upstream channels;

receiving a measure of usage interval start time, T_S, for each usage interval of a plurality of usage intervals;

deciding whether the measure of common maintenance start time, T_M, satisfies expression T_S≦

T_M<

T_S+L, for each usage interval of the plurality of usage intervals, wherein is L is a measure of usage interval length for the usage interval;

when the measure of common maintenance start time, T_M, satisfies expression T_S≦

T_M<

T_S+L, for each usage interval of the plurality of usage intervals, scheduling N maintenance intervals to start at the measure of common maintenance start time; and

instructing the initializing network devices to range during the plurality of maintenance intervals.

12. A computer readable medium, having stored therein instructions for causing a central processing unit to execute the method of claim 11.