ADAPTIVE SCHEDULING OF VOICE TRAFFIC IN A MULTI-CARRIER COMMUNICATION ENVIRONMENT

• US 20070189320A1
• Filed: 03/24/2005
• Published: 08/16/2007
• Est. Priority Date: 03/31/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Tong, Wen, Zhu, Peiying, Wu, Jianming
• Granted Patent: US 8,165,009 B2
• Time in Patent Office: Days
• US Class Current: 370/437
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• 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 5/006 Quality of the received signal, e.g. BER, SNR, water filling
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 72/1263 Mapping of traffic onto schedule, e.g. scheduled allocation or multiplexing of flows
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

The present invention provides a technique for scheduling data, and in particular, scheduling real-time or voice data for transmissions during a transmit time interval in a multi-carrier communication environment. For each transmit time interval, channel condition indicia for multiple users is determined, and an iterative scheduling process is then implemented based in part on the channel condition indicia. The iterative scheduling initially preassigns select tones for each of the remaining users that have not been permanently assigned tones for the given transmit time interval. Next, the remaining user having the least favorable channel conditions is selected as an active user. The newly selected active user is then permanently assigned the select tones that were initially pre-assigned to that particular user. The permanently assigned tones are removed from consideration, and the process is repeated until all the remaining users are permanently assigned unique tones for scheduling.

Claims

1. A method for scheduling data for transmission during a transmit time interval in a multi-carrier communication environment comprising:

determining channel condition indicia for a plurality of users;

in an iterative manner;

pre-assigning select OFDM tones for each remaining user of the plurality of users that has not been permanently assigned tones for the transmit time interval;

selecting a remaining user having least favorable channel conditions as an active user; and

permanently assigning to the active user the select OFDM tones pre-assigned to the active user, wherein once the select OFDM tones are permanently assigned to the active user, the active user is no longer a remaining user.

2. The method of claim 1 wherein the select tones permanently assigned to active users are no longer available for pre-assignment to the remaining users.

3. The method of claim 1 further comprising initiating scheduling for the transmit time interval for the plurality of users using the select tones permanently assigned to each of the plurality of users.

4. The method of claim 1 wherein for each remaining user, pre-assigning the select tones comprises:

sorting tones in light of channel condition information; and

selecting ones of the tones having most favorable channel conditions as the select tones.

5. The method of claim 4 wherein for each remaining user, selecting ones of the tones further comprises minimizing a number of tones pre-assigned as select tones while ensuring a target data rate is achieved in light of the channel conditions associated with each of the select tones.

6. The method of claim 1 further comprising:

determining a number of the select tones for transmitting original data and a number of the select tones for transmitting redundant data; and

increasing the number of the select tones for transmitting redundant data for remaining users with poor channel conditions.

7. The method of claim 1 wherein selecting a remaining user further comprises:

determining a scheduling factor for each remaining user based on the channel condition indicia; and

selecting the remaining user having the least favorable scheduling factor as the active user.

8. The method of claim 1 wherein the data scheduled for transmission is real-time data.

9. The method of claim 1 wherein the data scheduled for transmission is voice information.

10. The method of claim 1 wherein groups of the tones with a time and frequency continuum associated with the transmit time interval are associated with channels, and the tones are pre-assigned to the remaining users and permanently assigned to the active users according to corresponding channels.

11. The method of claim 1 wherein groups of tones are associated, and further comprising effecting signaling for scheduling based on the groups of tones to reduce signaling overhead.

12. The method of claim 1 wherein the number of tones pre-assigned to remaining users increases with each re-transmission attempt.

13. The method of claim 1 wherein the multi-carrier communication environment is an orthogonal frequency division multiplexing (OFDM) communication environment and the tones are OFDM tones.

14. A system for scheduling data for transmission during a transmit time interval in a multi-carrier communication environment comprising:

a communication interface;

a network interface; and

a control system associated with the communication interface and the network interface, the control system adapted to;

determine channel condition indicia for a plurality of users; and

in an iterative manner;

pre-assigning select tones for each remaining user of the plurality of users, which have not been permanently assigned tones for the transmit time interval;

selecting a remaining user having least favorable channel conditions as an active user; and

permanently assigning to the active user the select tones pre-assigned to the active user wherein once the select tones are permanently assigned to the active user, the active user is no longer a remaining user.

15. The system of claim 14 wherein the select tones permanently assigned to active users are no longer available for pre-assignment to the remaining users.

16. The system of claim 14 wherein the control system is further adapted to initiate scheduling for the transmit time interval for the plurality of users using the select tones permanently assigned to each of the plurality of users.

17. The system of claim 14 wherein for each remaining user, to pre-assign the select tones, the control system is further adapted to:

sort tones in light of channel condition information; and

select ones of the tones having most favorable channel conditions as the select tones.

18. The system of claim 17 wherein for each remaining user, to select ones of the tones, the control system is further adapted to minimize a number of tones pre-assigned as select tones while ensuring a target data rate is achieved in light of the channel conditions associated with each of the select tones.

19. The system of claim 14 wherein the control system is further adapted to:

determine a number of the select tones for transmitting original data and a number of the select tones for transmitting redundant data; and

increase the number of the select tones for transmitting redundant data for remaining users with poor channel conditions.

20. The system of claim 14 wherein to select a remaining user, the control system is further adapted to:

determine a scheduling factor for each remaining user based on the channel condition indicia; and

select the remaining user having the least favorable scheduling factor as the active user.

21. The system of claim 14 wherein the data scheduled for transmission is real-time data.

22. The system of claim 14 wherein the data scheduled for transmission is voice information.

23. The system of claim 14 wherein groups of the tones with a time and frequency continuum associated with the transmit time interval are associated with channels, and the tones are pre-assigned to the remaining users and permanently assigned to the active users according to corresponding channels.

24. The system of claim 14 wherein groups of tones are associated, and further comprising effecting signaling for scheduling based on the groups of tones to reduce signaling overhead.

25. The system of claim 14 wherein the number of tones pre-assigned to remaining users increases with each re-transmission attempt.

26. The system of claim 14 wherein the multi-carrier communication environment is an orthogonal frequency division multiplexing (OFDM) communication environment, and the tones are OFDM tones.