ADAPTIVE SCHEDULING FOR MULTI-CARRIER SYSTEMS

• US 20070286131A1
• Filed: 08/20/2007
• Published: 12/13/2007
• Est. Priority Date: 06/18/2001
• Status: Active Grant

• Current Assignee: Ericsson AB (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Wu, Jianming, Tong, Wen
• Granted Patent: US 7,860,066 B2
• Time in Patent Office: Days
• US Class Current: 370/337
• CPC Class Codes: H04W 72/52 based on load
• CPC Class Codes: H04W 72/535 based on resource usage policies

Abstract

A scheduler in a base station determines or estimates a cumulative throughput based on the scheduling criteria used by the base station. Based on the cumulative throughput for each slot, the mobile terminals are divided into one of two groups. The first group is provided for mobile terminals having a lower throughput, while the remaining mobile terminals are placed in a second group associated with higher throughput. The mobile terminal in the first group having the lowest throughput has data scheduled for transmission on the next slot over the best available carrier. The remaining mobile terminals in the first group are iteratively scheduled for transmission on the best remaining carriers, until no mobile terminals remain. Once scheduling for the first group is complete, scheduling for the second group can take place. Preferably, scheduling for the second group is performed to maximize throughput on the remaining carrier or carriers.

Claims

1. A method for scheduling data for transmission to mobile terminals in a multi-carrier, wireless communication environment comprising:

a) determining a cumulated throughput up to or through a given slot of a given frame for each of the mobile terminals;

b) placing mobile terminals having a lower cumulated throughput in a first group;

c) placing mobile terminals having a higher cumulated throughput in a second group;

d) for the first group, iteratively scheduling data for a slot for transmission to the mobile terminals with a lowest cumulated throughput on a best available carrier until the data for each mobile terminal in the first group is scheduled, wherein once data is scheduled for the slot on the carrier the carrier becomes unavailable; and

e) for the second group, scheduling data for the slot for transmission to at least one mobile terminal on an available carrier to maximize throughput.

2. The method of claim 1 wherein steps a through e are iteratively provided on a slot-by-slot basis for each frame.

3. The method of claim 1 wherein steps a through e are iteratively provided after x slots into each frame.

4. The method of claim 1 wherein scheduling for the second group to maximize throughput uses a proportional fairness scheduling criteria.

5. The method of claim 1 wherein scheduling for the second group to maximize throughput uses a maximum carrier-to-interference ratio scheduling criteria.

6. The method of claim 1 wherein the cumulated throughput for each mobile terminal is an estimate of actual throughput for each mobile terminal.

7. The method of claim 6 wherein the cumulated throughput is estimated by:

a) creating a channel matrix for each mobile terminal and each carrier;

b) mapping the channel matrix into a transmission rate matrix for each mobile terminal and each carrier based on available coding and modulation schemes; and

c) estimating the cumulated throughput based at least in part on scheduling criteria used during scheduling in the first and second groups.

8. The method of claim 1 wherein:

a) there are three carriers;

b) the first group includes a first mobile terminal having a lowest cumulated throughput and a second mobile terminal having a next-to-lowest cumulated throughput;

c) for the first group, the method comprises;

i) scheduling data for transmission to the first mobile terminal during the slot on a best available carrier for transmitting data to the first mobile terminal; and

ii) scheduling data for transmission to the second mobile terminal during the slot on a best available carrier selected from the remaining carriers for transmission to the second mobile terminal; and

d) for the second group, the method comprises;

i) selecting a mobile terminal from the second group capable of maximizing throughput over a remaining one of the three carriers; and

ii) scheduling data for the slot for transmission to a selected mobile terminal on an available carrier to maximize throughput.

9. A system for scheduling data for transmission to mobile terminals in a wireless communication environment comprising a control plane and a scheduler adapted to:

a) determine a cumulated throughput up to or through a given slot of a given frame for each of the mobile terminals;

b) place mobile terminals having a lower cumulated throughput in a first group;

c) place mobile terminals having a higher cumulated throughput in a second group;

d) for the first group, iteratively schedule data for a slot for transmission to the mobile terminals with a lowest cumulated throughput on a best available carrier until the data for each mobile terminal in the first group is scheduled, wherein once data is scheduled for the slot on the carrier the carrier becomes unavailable; and

e) for the second group, schedule data for the slot for transmission to at least one mobile terminal on an available carrier to maximize throughput.

10. The system of claim 9 wherein the control plane and scheduler are further adapted to iteratively provide steps a through e on a slot-by-slot basis for each frame.

11. The system of claim 9 wherein the control plane and scheduler are further adapted to iteratively provide steps a through e after x slots into each frame.

12. The system of claim 9 wherein scheduling for the second group to maximize throughput uses a proportional fairness scheduling criteria.

13. The system of claim 9 wherein scheduling for the second group to maximize throughput uses a maximum carrier-to-interference ratio scheduling criteria.

14. The system of claim 9 wherein the cumulated throughput for each mobile terminal is an estimate of actual throughput for each mobile terminal.

15. The system of claim 14 wherein the control plane and scheduler are adapted to estimate the cumulated throughput by:

a) creating a channel matrix for each mobile terminal and each carrier;

b) mapping the channel matrix into a transmission rate matrix for each mobile terminal and each carrier based on available coding and modulation schemes; and

c) estimating the cumulated throughput based at least in part on scheduling criteria used during scheduling in the first and second groups.

16. The system of claim 9 wherein:

a) there are three carriers;

b) the first group includes a first mobile terminal having a lowest cumulated throughput and a second mobile terminal having a next-to-lowest cumulated throughput;

c) for the first group, the control plane and scheduler are adapted to;

i) schedule data for transmission to the first mobile terminal during the slot on the best available carrier for transmitting data to the first mobile terminal; and

ii) schedule data for transmission to the second mobile terminal during the slot on a best available carrier selected from the remaining carriers for transmission to the second mobile terminal; and

d) for the second group, the control plane and scheduler are adapted to;

i) select a mobile terminal from the second group capable of maximizing throughput over a remaining one of the three carriers; and

ii) schedule data for the slot for transmission to a selected mobile terminal on an available carrier to maximize throughput.

17. A method for scheduling data for transmission to mobile terminals in a three carrier, wireless communication environment comprising:

a) determining a cumulated throughput up to or through a given slot of a given frame for each of the mobile terminals;

b) placing a first mobile terminal having a lowest cumulated throughput and a second mobile terminal having a next-to-lowest cumulated throughput in a first group;

c) placing all other mobile terminals in a second group;

d) for the first group;

i. scheduling data for transmission to the first mobile terminal during the slot on a best available carrier for transmitting data to the first mobile terminal; and

ii. scheduling data for transmission to the second mobile terminal during the slot on a best available carrier selected from the remaining carriers for transmission to the second mobile terminal, wherein once data is scheduled for the slot on the carrier the carrier becomes unavailable; and

e) for the second group, scheduling data for the slot for transmission to at least one mobile terminal on an available carrier to maximize throughput.

18. The method of claim 17 wherein steps a through e are iteratively provided on a slot-by-slot basis for each frame.

19. The method of claim 17 wherein steps a through e are iteratively provided after x slots into each frame.

20. The method of claim 17 wherein scheduling for the second group to maximize throughput uses a proportional fairness scheduling criteria.

21. The method of claim 17 wherein scheduling for the second group to maximize throughput uses a maximum carrier-to-interference ratio scheduling criteria.

22. The method of claim 17 wherein the cumulated throughput for each mobile terminal is an estimate of actual throughput for each mobile terminal.

23. The method of claim 22 wherein the cumulated throughput is estimated by:

a) creating a channel matrix for each mobile terminal and each carrier;

b) mapping the channel matrix into a transmission rate matrix for each mobile terminal and each carrier based on available coding and modulation schemes; and

c) estimating the cumulated throughput based at least in part on scheduling criteria used during scheduling in the first and second groups.