Segment sensitive scheduling

• US 9,209,956 B2
• Filed: 10/27/2005
• Issued: 12/08/2015
• Est. Priority Date: 08/22/2005
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gorokhov, Alexei, Ji, Tingfang
• Primary Examiner(s): TRAN, PHUC H
• Application Number:
  US11/260,924
• Publication Number:
  US 20070060178A1
• Time in Patent Office: 3,694 Days
• Field of Search: 370/445, 370/448, 370/485, 375/132
• US Class Current: 1/1
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/1812 Hybrid protocols; Hybrid automatic repeat request [HARQ]
• CPC Class Codes: H04L 25/0398 Restoration of channel reciprocity
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0048 Allocation of pilot signals, i.e. of signals known to the receiver
• CPC Class Codes: H04L 5/0057 Physical resource allocation for CQI
• 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: H04L 5/1438 Negotiation of transmission parameters prior to communication modified according to link quality H04L1/0001

Abstract

Systems and methods of scheduling sub-carriers in an OFDMA system in which a scheduler takes into account channel conditions experienced by the communication devices to optimize channel conditions. The scheduler can partition a set of sub-carriers spanning an operating bandwidth into a plurality of segments. The segments can include a plurality of global segments that each includes a distinct non-contiguous subset of the sub-carriers spanning substantially the entire operating bandwidth. One or more of the global segments can be further partitioned into a plurality of local segments that each has a bandwidth that is less than a channel coherence bandwidth. The scheduler determines channel characteristics experienced by each communication device via reporting or channel estimation, and allocates one or more segments to communication links for each device according to the channel characteristics.

Claims

1. A method of scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band partitioned into a plurality of segments, the method comprising:

determining at a transmitter a segment preference indicative of a preferred segment determined by a receiver from a plurality of segments substantially spanning at least a portion of the operating band and based upon channel characteristics experienced by the receiver of a remote device and user data constraints of data to be transmitted; and

assigning at the transmitter a subset of sub-carriers within the preferred segment to a particular communication link associated with the segment preference.

2. The method of claim 1, wherein the plurality of segments comprises at least one global segment having a non-contiguous subset of the plurality of sub-carriers that span a substantial fraction of the operating bandwidth.

3. The method of claim 2, wherein the plurality of segments further comprises a plurality of local segments, each local segment having a subset of the plurality of sub-carriers distinct from any other local segment or global segment, and each local segment having a bandwidth less than a total bandwidth.

4. The method of claim 1, wherein the plurality of segments comprises a plurality of local segments, each local segment having a distinct subset of the plurality of sub-carriers, and each local segment having a bandwidth less than a total bandwidth.

5. The method of claim 4, wherein the plurality of local segments have substantially equal bandwidths.

6. The method of claim 4, wherein each of the plurality of local segments comprises a multiple of 16 sub-carriers.

7. The method of claim 1, wherein determining the segment preference comprises analyzing a pilot signal to determine channel characteristics corresponding to each of the plurality of segments, and selecting a preferred segment based on a comparison of the segment channel characteristics.

8. The method of claim 1, wherein determining the segment preference comprises:

receiving a reverse link pilot signal transmitted from a transmitter co-located with the receiver;

determining channel characteristics corresponding to at least two of the plurality of segments; and

selecting a segment base in part on the channel characteristics.

9. The method of claim 1, wherein determining the channel preference comprises receiving a reporting message from the receiver indicative of the segment preference.

10. The method of claim 1, wherein determining the segment preference comprises determining the segment preference based on a reverse link pilot signal;

and

wherein assigning the subset of sub-carriers comprises assigning the subset of carriers to a reverse link communication.

11. The method of claim 1, wherein determining the segment preference comprises determining the segment preference based on a reverse link pilot signal;

and

wherein assigning the subset of sub-carriers comprises assigning the subset of sub-carriers to a forward link communication.

12. The method of claim 1, wherein assigning the subset of sub-carriers comprises mapping a data stream to the subset of sub-carriers in a forward link transmission.

13. The method of claim 1, wherein assigning the subset of sub-carriers comprises transmitting an assignment message to the receiver identifying at least one of the subset of sub-carriers.

14. The method of claim 1, further comprising enforcing a frequency hopping scheme within the preferred segment.

15. A method of scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band partitioned into a plurality of segments, the method comprising:

determining user data constraints;

assigning sub-carriers from a global segment having a non-contiguous subset of sub-carriers spanning a substantial fraction of the operating band if the user data constraints include a data bandwidth requirement greater than a total bandwidth;

determining, if the data bandwidth requirement is not greater than the total bandwidth, a segment preference indicative of a preferred local segment based upon channel characteristics experienced by a receiver, the preferred local segment selected from a plurality of local segments, each of the plurality of local segments having a bandwidth less than the total bandwidth; and

assigning a subset of sub-carriers within the preferred local segment to a communication link associated with the segment preference.

16. The method of claim 15, wherein the global segment includes sub-carriers that span at least one half the operating bandwidth.

17. The method of claim 15, wherein determining the segment preference comprises:

analyzing a received pilot signal to determine channel characteristics corresponding to each of the plurality of segments;

comparing the channel characteristics corresponding to each of the plurality of segments; and

selecting a segment corresponding to a greatest signal to noise ratio (SNR) value.

18. The method of claim 15, wherein determining the segment preference comprises receiving a reporting message indicating the segment preference.

19. An apparatus for channel sensitive scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band, the apparatus comprising:

means for determining at a transmitter a channel preference indicative of a preferred segment determined by a receiver from a plurality of segments substantially spanning at least a portion of the operating band and based upon channel characteristics experienced by the receiver of a remote device and user data constraints of data to be transmitted; and

means for assigning at the transmitter a subset of sub-carriers within the preferred segment to a particular communication link associated with the channel preference.

20. The apparatus of claim 19, wherein the means for determining the channel preference comprises:

means for receiving a pilot signal;

means for determining a channel characteristic corresponding to each of the plurality of segments; and

means for selecting the channel preference based on the channel characteristics.

21. The apparatus of claim 19, wherein the means for determining the channel preference comprises means for receiving a channel reporting message indicative of the channel preference.

22. An apparatus for channel sensitive scheduling in a communication system including a plurality of sub-carriers spanning an operating frequency band, the apparatus comprising:

a scheduler configured to;

determine a channel preference indicative of a preferred segment determined by a receiver from a plurality of segments substantially spanning at least a portion of the operating band and based upon channel characteristics experienced by the receiver of a remote device and user data constraints of data to be transmitted; and

assign a subset of sub-carriers within the preferred segment to a particular communication link associated with the channel preference.

23. The apparatus of claim 22, further comprising a transceiver coupled to the scheduler and including a transmitter module and a receiver module.

24. The apparatus of claim 23, the scheduler configured to receive a channel characteristic reporting message from the remote device via the transceiver.

25. The apparatus of claim 22, the scheduler comprising a channel estimator configured to determine a channel estimate for the preferred segment based on the channel characteristics.

26. A non-transitory machine-readable medium comprising instructions executable by a processing system in wireless communication device, the instructions comprising code for:

determining at a transmitter of the wireless communication device a segment preference indicative of a preferred segment determined by a receiver from a plurality of segments substantially spanning at least a portion of the operating band and based upon channel characteristics experienced by the receiver of a remote device and user data constraints of data to be transmitted; and

assigning at the transmitter a subset of sub-carriers within the preferred segment to a particular communication link associated with the segment preference.

27. The non-transitory machine-readable medium of claim 26, further comprising code for analyzing a pilot signal to determine channel characteristics corresponding to each of the plurality of segments.

28. The non-transitory machine-readable medium of claim 26, further comprising code for:

receiving a reverse link pilot signal transmitted from a transmitter co-located with the receiver;

determining channel characteristics corresponding to at least two of the plurality of segments; and

selecting a segment base in part on the channel characteristics.

29. The non-transitory machine-readable medium of claim 26, further comprising code for utilizing a frequency hopping scheme within the preferred segment.