Method and apparatus for creating virtual upstream channels for enhanced lookahead channel parameter testing

• US 7,039,939 B1
• Filed: 05/09/2000
• Issued: 05/02/2006
• Est. Priority Date: 05/09/2000
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Khaunte, Sunil, Leano, Chrisanto, Millet, Mark E.
• Primary Examiner(s): Bui, Kieu-Oanh
• Application Number:
  US09/568,795
• Time in Patent Office: 2,184 Days
• Field of Search: 725124-127, 725/111, 725/107, 725/116, 725/118, 725/120, 725/121, 375/222, 370/329, 370354-442
• US Class Current: 725/111
• CPC Class Codes: H04H 60/97 using uplink of the CATV systems

Abstract

Methods, apparatus, and computer-readable media are disclosed for creating a virtual lookahead upstream receiver in a single physical upstream receiver in a CMTS, thereby avoiding having to dedicate an upstream receiver strictly for lookahead capability. A lookahead receiver is used to determine whether a potential alternative frequency is better than the frequency presently being used. A physical upstream receiver is assigned to operate under a set of operational parameters associated with a logical lookahead receiver during a particular time slot. The logical receiver receives upstream data from a selected test modem using an alternative upstream frequency. It is then determined whether the alternative upstream frequency is preferable over the frequency presently being used. If so, the physical receiver is configured to operate normally under the set of operational parameters associated with the logical receiver. At this stage, all modems in a particular group, including the selected modem, hop over to the alternative frequency. The physical receiver can be divided into any number of logical receivers.

Claims

1. A method of using a physical upstream receiver, the method comprising:

in a normal mode, assigning a first set of parameters to the physical receiver for communicating with cable modems in a first frequency;

in a lookahead mode, assigning a second set of parameters to the physical upstream receiver for communicating with a device in a second frequency, the second frequency being different from the first frequency;

determining whether the second frequency should be used to communicate with the cable modems; and

performing transitions between the normal mode and the lookahead mode periodically.

2. The method of claim 1, wherein the normal mode and the lookahead mode are performed alternately.

3. The method of claim 2, wherein the lookahead mode is performed multiple times during operation in the normal mode, and wherein each time the lookahead mode is performed, the physical ups receiver communicates with the device in a different frequency.

4. The method of claim 3, wherein the device is selected from the cable modems, the selected cable modem being inactive or not communicating.

5. The method of claim 4, further comprising identifying the selected modem by a MAC address or SID.

6. The method of claim 4, wherein the lookahead mode is performed for a short period of time such that the lookahead mode does not substantially interrupt communication of the cable modems.

7. The method of claim 6, wherein the physical upstream receiver receives data regarding the quality of the second frequency from the device during the lookahead mode.

8. The method of claim 1, wherein assigning the second set of parameters includes gig the physical upstream receiver a port number in the CMTS that is different from a port number for the normal mode.

9. The method of claim 1, wherein determining whether the second frequency should be used includes comparing the quality of the second frequency with a threshold signal quality.

10. The method of claim 1, further comprising assigning the second set of parameters to the physical upstream receiver for communicating with the cable modems if the second frequency is determined to be used to communicate with the cable modems.

11. The method of claim 1, wherein the first and second sets of parameters include at least one of frequency center, channel width, and modulation format.

12. The method of claim 1, further comprising sending a fit upstream channel change (UCC) command to the device instructing the device to use a new port in place of a present port.

13. The method of claim 12, further comprising sending a second UCC command to the device instructing the device to return to the present port.

14. The method of claim 1, further comprising sending an upstream channel descriptor (UCD) message to the device.

15. A physical upstream receiver comprising:

one or more processors; and

memory in communication with at least one of the one or more processors,

wherein at least one of the one or more processors is configured to

in a normal mode, communicate with cable modems in a first frequency using a first set of parameters,

in a lookahead mode, communicate with a device in a second frequency using a second set of parameters, the second frequency being different from the first frequency,

determine whether the second frequency should be used to communicate with the cable modems, and

perform transitions between the normal mode and the lookahead mode periodically.

16. The physical upstream receiver of claim 15, wherein the physical upstream receiver is configured through MAC instructions to perform the normal mode and the lookahead mode.

17. The physical upstream receiver of claim 16, wherein the MAC instructions include an upstream channel change message and an upstream channel descriptor message.

18. The physical upstream receiver of claim 15, wherein the normal mode and the lookahead mode are performed alternately.

19. The physical upstream receiver of claim 15, wherein when the lookahead mode is entered, the second frequency is changed to a different frequency if the second frequency is determined not to be used to communicate with the cable modems.

20. The physical upstream receiver of claim 15, wherein the device is selected from the cable modems the selected cable modem being inactive or not communicating.

21. A physical upstream receiver comprising:

means for, in a normal mode, communicating with cable modems in a first frequency using a first set of parameters;

means for, in a lookahead mode, communicating with a device in a second frequency using a second set of parameters, the second frequency being different from the first frequency;

means for determining whether the second frequency should be used to communicate with the cable modems; and

means for perform transitions between the normal mode and the lookahead mode periodically.

22. The physical upstream receiver of claim 21, wherein the physical upstream receiver is configured through MAC instructions to perform the normal mode and the lookahead mode.

23. The physical upstream receiver of claim 22, wherein the MAC instructions include an upstream channel change message and an upstream channel descriptor message.

24. The physical upstream receiver of claim 21, wherein the normal mode and the lookahead mode are performed alternately.

25. The physical upstream receiver of claim 21, wherein when the lookahead mode is entered, the second frequency is changed to a different frequency if the second frequency is determined not to be used to communicate with the cable modems.

26. The physical upstream receiver of claim 21, wherein the device is selected from the cable modems, the selected cable modem beg inactive or not communicating.

27. A computer readable medium on which is provided a computer code for using a physical upstream receiver, the computer code comprising instructions for:

in a normal mode, assigning a first set of parameters to the physical upstream receiver for communicating with cable modems in a first frequency;

in a lookahead mode, assigning a second set of parameters to the physical upstream receiver for communicating with a device in a second frequency, the second frequency being different from the first frequency;

determining whether the second frequency should be used to communicate with the cable modems;

performing between the normal mode and the lookahead mode periodically.

28. The computer readable medium of claim 27, wherein the normal mode and the lookahead mode are performed alternately.

29. The computer readable medium of claim 28, wherein when the lookahead mode is entered, the second frequency is changed to a different frequency if the second frequency is determined not to be used to communicate with the cable modems.

30. The computer readable medium of claim 29, wherein the device is selected from the cable modems, the selected cable modem being inactive or not communicating.