BANDWIDTH ALLOCATION BASE STATION AND METHOD FOR ALLOCATING UPLINK BANDWIDTH USING SDMA

• US 20100008331A1
• Filed: 07/09/2008
• Published: 01/14/2010
• Est. Priority Date: 07/09/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Yin, Hujun, Lin, Xintian E., Li, Qinghua, Oyman, Ozgur, Wong, Wendy C.
• Granted Patent: US 8,243,690 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04L 5/0026 Division using four or more dimensions
• CPC Class Codes: H04L 5/0039 Frequency-contiguous, i.e. with no allocation of frequencies for one user or terminal between the frequencies allocated to another
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/0051 of dedicated pilots, i.e. pilots destined for a single user or terminal
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0062 Avoidance of ingress interference, e.g. ham radio channels
• CPC Class Codes: H04L 5/0094 Indication of how sub-channels of the path are allocated

Abstract

Embodiments of a base station and methods for allocating uplink bandwidth using SDMA are generally described herein. In some embodiments, uplink bandwidth request messages are received on a bandwidth request contention channel from one or more subscriber stations. The uplink bandwidth request messages are generated by the subscriber stations by modulating pilot subcarriers of a randomly selected disjoint pilot pattern with a randomly selected orthogonal sequence. The base station allocates uplink bandwidth to the subscriber stations when the uplink bandwidth request messages are successfully detected and decoded. The base station uses an SDMA technique to determine channel responses based on the orthogonal sequences to detect and decode the uplink bandwidth request messages.

Claims

1. A bandwidth allocation process comprising:

receiving, over a bandwidth request contention channel, orthogonal sequences sent in two or more tiles from subscriber stations, each of the two or more tiles comprising a time-frequency block; and

detecting one or more of the subscriber stations by applying each of a plurality of the orthogonal sequences to the received orthogonal sequences,

wherein a base station receives the orthogonal sequences from the subscriber stations through a plurality of antennas and uses a space-division multiple access (SDMA) technique to help differentiate two or more of the orthogonal sequences that have collided.

2. The method of claim 1 wherein the orthogonal sequences are sent by the subscriber stations during an uplink subframe, and

wherein the method further comprises broadcasting in a downlink subframe, orthogonal codes corresponding to the detected subscriber stations and an assignment of one of a plurality disjoint pilot patterns to each detected subscriber station, each disjoint pilot pattern for subsequent transmission by a detected subscriber station of an uplink bandwidth request message in a next uplink subframe.

3. The method of claim 2 wherein the disjoint pilot patterns comprise orthogonal pilot subcarriers and non-orthogonal data subcarriers.

4. The method of claim 3 wherein at least some of the subscriber stations use the non-orthogonal data subcarriers for transmission of the uplink bandwidth request messages in the next uplink subframe, and

wherein the method further comprises:

receiving uplink bandwidth request messages in the next uplink subframe from two or more of the subscriber stations; and

using SDMA techniques to separate the uplink bandwidth request messages sent by the two or more subscriber stations.

5. The method of claim 4 wherein the detected subscriber stations transmit their uplink bandwidth request messages using one or more antennas, and

wherein the base station receives the uplink bandwidth request messages with two or more antennas.

6. The method of claim 1 wherein the orthogonal sequences are randomly selected by the subscriber stations,

wherein the subscriber stations transmit the randomly selected orthogonal sequences in the two or more tiles during an uplink subframe to request uplink bandwidth, and

wherein each tile comprises a time-frequency block of the bandwidth request contention channel.

7. The method of claim 1 wherein the subscriber stations refrain from transmitting code-division multiple access (CDMA) codes to the base station over the bandwidth request contention channel to request uplink bandwidth.

8. A base station to allocate bandwidth to subscriber stations, the base station comprising:

physical-layer circuitry to receive through two or more antennas over a bandwidth request contention channel, orthogonal sequences sent in two or more tiles from subscriber stations, each of the two or more tiles comprising a time-frequency block; and

signal processing circuitry to detect one or more of the subscriber stations by applying each of a plurality of the orthogonal sequences to the received orthogonal sequences,

wherein the signal processing circuitry uses a space-division multiple access (SDMA) technique to help differentiate two or more of the orthogonal sequences that have collided.

9. The base station of claim 8 wherein the orthogonal sequences are sent by the subscriber stations during an uplink subframe, and

wherein the physical-layer circuitry of the base station is configured to broadcast in a downlink subframe, orthogonal codes corresponding to the detected subscriber stations and an assignment of one of a plurality disjoint pilot patterns to each detected subscriber station, each disjoint pilot pattern for subsequent transmission by a detected subscriber station of an uplink bandwidth request message in a next uplink subframe.

10. The base station of claim 9 wherein the disjoint pilot patterns comprise orthogonal pilot subcarriers and non-orthogonal data subcarriers.

11. A method for allocating uplink bandwidth using space-division multiple access (SDMA) comprising:

receiving uplink bandwidth request messages on a bandwidth request contention channel from one or more subscriber stations, the uplink bandwidth request messages being generated by the subscriber stations by modulating pilot subcarriers of a randomly selected disjoint pilot pattern with a randomly selected orthogonal sequence;

providing allocations of uplink bandwidth to the subscriber stations when the uplink bandwidth request messages are successfully detected and decoded; and

applying SDMA techniques to determine channel responses based on the orthogonal sequences to detect and decode the uplink bandwidth request messages.

12. The method of claim 11 further comprising receiving, by a base station, the uplink bandwidth request messages through two or more antennas.

13. The method of claim 12 wherein the subscriber stations randomly select one of a plurality of disjoint pilot patterns and one of a plurality of orthogonal sequences prior to transmitting the uplink bandwidth request messages, and

wherein data subcarriers of the bandwidth request contention channel are modulated by the subscriber stations with an uplink bandwidth request data element.

14. The method of claim 13 wherein the method is performed by a broadband wireless access network base station that communicates with the subscriber stations using orthogonal frequency division multiple access (OFDMA) downlink subframes, and

wherein the method further comprises determining the channel responses by applying each of the orthogonal sequences of the plurality to signals received the pilot subcarriers of the disjoint pilot patterns of the bandwidth request contention channel.

15. The method of claim 13 wherein when a single uplink bandwidth request is received from one subscriber station, the method includes:

detecting the uplink bandwidth request using maximum ratio combining; and

allocating uplink bandwidth in a next downlink subframe for an uplink data transmission to the one detected subscriber station.

16. The method of claim 15 wherein when two colliding uplink bandwidth requests are received from two subscriber stations over the bandwidth request contention channel when the two subscriber stations have randomly selected different disjoint pilot patterns and different orthogonal sequences, the method includes:

detecting and decoding the uplink bandwidth requests using a spatial demultiplexing technique; and

allocating uplink bandwidth for an uplink data transmission to each of the subscriber stations in a next downlink subframe.

17. The method of claim 16 wherein the spatial demultiplexing technique comprises one of either a minimum mean square error (MMSE) estimation technique or a zero-forcing technique.

18. The method of claim 16 wherein when two colliding uplink bandwidth requests are received from two subscriber stations over the bandwidth request contention channel when the two subscriber stations have randomly selected the same disjoint pilot pattern and different orthogonal sequences, the method includes:

attempting to detect and decode at least one of the uplink bandwidth requests using a spatial demultiplexing technique; and

allocating uplink bandwidth for an uplink data transmission to at least one of the subscriber stations when at least one subscriber station was successfully detected.

19. The method of claim 16 wherein when two colliding uplink bandwidth requests are received from two subscriber stations over the bandwidth request contention channel when the two subscriber stations have selected the same disjoint pilot pattern and the same orthogonal sequences, the method includes:

refraining from allocating bandwidth for an uplink data transmission to either of the two subscriber stations when the uplink bandwidth requests and unable to be detected and decoded.

20. The method of claim 16 wherein a plurality of subscriber stations randomly select one of two disjoint pilot patterns and one of two orthogonal sequences for transmission of uplink bandwidth request messages, and

wherein when more than two colliding uplink bandwidth requests are received from more than two subscriber stations over the bandwidth request contention channel, the method includes:

attempting to detect one or more of the orthogonal sequences and the pilot patterns to detect one or more subscriber stations; and

broadcasting the one or more detected orthogonal sequences and pilot patterns to allocate a transmission resource for each detected subscriber station, the transmission resource to be used by the detected subscriber station to retransmit a contention-free bandwidth request message.

21. A method for requesting uplink bandwidth allocation by subscriber stations comprising:

randomly selecting one of a plurality of disjoint pilot patterns and one of a plurality of orthogonal sequences; and

transmitting uplink bandwidth request messages on a bandwidth request contention channel, the uplink bandwidth request messages being generated by subscriber stations by modulating pilot subcarriers of the randomly selected disjoint pilot pattern with the randomly selected orthogonal sequence,

wherein allocations of uplink bandwidth are provided to the subscriber stations when the uplink bandwidth request messages are successfully detected and decoded by a receiving base station.

22. The method of claim 21 wherein a base station receives the uplink bandwidth request messages through two or more antennas and applies space-division multiple access (SDMA) techniques to determine channel responses based on the orthogonal sequences to detect and decode the uplink bandwidth request messages.

23. The method of claim 22 further comprising modulating data subcarriers of the bandwidth request contention channel with an uplink bandwidth request data element.

24. A base station to allocate bandwidth to subscriber stations, the base station comprising:

physical-layer circuitry to receive through two or more antennas over a bandwidth request contention channel, uplink bandwidth request messages on a bandwidth request contention channel from one or more subscriber stations, the uplink bandwidth request messages being generated by the subscriber stations by modulating pilot subcarriers of a randomly selected disjoint pilot pattern with a randomly selected orthogonal sequence; and

signal processing circuitry determine allocations of uplink bandwidth for the subscriber stations when the uplink bandwidth request messages are successfully detected and decoded,

wherein the signal processing circuitry applies space-division multiple access (SDMA) techniques to determine channel responses based on the orthogonal sequences to detect and decode the uplink bandwidth request messages.

25. The base station of claim 24 wherein the physical-layer circuitry receives the uplink bandwidth request messages through two or more antennas,

wherein the subscriber stations randomly select one of a plurality of disjoint pilot patterns and one of a plurality of orthogonal sequences prior to transmitting the uplink bandwidth request messages, and

wherein data subcarriers of the bandwidth request contention channel are modulated by the subscriber stations with an uplink bandwidth request data element.

26. The base station of claim 25 wherein the base station is a broadband wireless access network base station that communicates with the subscriber stations using orthogonal frequency division multiple access (OFDMA) downlink subframes, and

wherein the signal processing circuitry is configured to determine the channel responses by applying each of the orthogonal sequences of the plurality to signals received the pilot subcarriers of the disjoint pilot patterns of the bandwidth request contention channel.