WIRELESS ACCESS NETWORK AND METHOD FOR ALLOCATING TIME AND FREQUENCY RESOURCES

• US 20070223440A1
• Filed: 03/16/2007
• Published: 09/27/2007
• Est. Priority Date: 03/20/2006
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Intel Corporation
• Inventors: Ho, Minnie, Li, Qinghua, Talwar, Shilpa, Lin, Xintian, Somayazulu, Vallabhajosyula
• Granted Patent: US 8,131,306 B2
• Time in Patent Office: Days
• US Class Current: 370/342
• CPC Class Codes: H04B 7/02 Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas RAKE receivers H04B1/7115
• CPC Class Codes: H04L 5/00 Arrangements affording multiple use of the transmission path
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/51 based on terminal or device properties
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

Embodiments of a wireless access network and method for allocation time and frequency resources are generally described herein. Other embodiments may be described and claimed. In some embodiments, a base station allocates contiguous groups of data subcarriers of a downlink subframe to closed-loop user stations, and allocates the remaining data subcarriers of the downlink subframe to open-loop user stations to increase frequency diversity.

Claims

1. In a wireless-access network, a method for allocating time-frequency units of a downlink subframe comprising:

allocating contiguous groups of data subcarriers of the downlink subframe to closed-loop user stations; and

allocating remaining data subcarriers of the downlink subframe to open-loop user stations to increase frequency diversity.

2. The method of claim 1 wherein the downlink subframe comprises a plurality of time-units, and

wherein the method further comprises:

allocating the contiguous groups of the data subcarriers to the closed-loop user stations for each time-unit within the downlink subframe; and

allocating the remaining data subcarriers non-contiguously to the open-loop user stations for each time-unit within the downlink subframe.

3. The method of claim 2 wherein the wireless-access network is an orthogonal frequency division multiple access (OFDMA) network,

wherein each time-unit comprises an OFDMA symbol,

wherein allocating the contiguous groups of the data subcarriers to the closed-loop user stations comprises allocating the same contiguous groups of the data subcarriers to the closed-loop user stations for a plurality of OFDMA symbols, and

wherein allocating the remaining data subcarriers to the open-loop user stations comprises reallocating the remaining data subcarriers to the open-loop user stations for each OFDMA symbol.

4. The method of claim 2 wherein for each time-unit, the contiguous groups of data subcarriers are allocated to the closed-loop user stations prior to the allocation of the remaining data subcarriers to the open-loop user stations.

5. The method of claim 1 wherein the remaining data subcarriers are allocated to the open-loop user stations by:

systematically partitioning a sequence of remaining contiguous data subcarriers into multiple subsequences; and

allocating data subcarriers associated with one of the multiple sequences to the open-loop user stations on a per-sequence basis.

6. The method of claim 5 wherein the multiple subsequences are selected to have varying lengths.

7. The method of claim 5 wherein the multiple subsequences are selected to have the same length.

8. The method of claim 2 further comprising reallocating remaining data subcarriers of the downlink subframe to open-loop user stations by:

cyclically shifting the remaining data subcarriers for each one or more time units; and

allocating the remaining data subcarriers to the open-loop user stations based on the cyclically shifting.

9. The method of claim 2 further comprising reallocating remaining data subcarriers of the downlink subframe to open-loop user stations by:

renumbering the remaining data subcarriers for each one or more time units; and

allocating the remaining data subcarriers to the open-loop user stations based on the renumbering.

10. The method of claim 1 wherein the closed-loop user stations comprise user stations with a known channel state,

wherein the open-loop user stations comprise user stations with an unknown channel state, and

wherein the contiguous groups of data subcarriers are selected for allocation by a base station based on channel state information provided by the closed-loop user stations.

11. The method of claim 1 wherein closed-loop user stations comprise user stations with a known channel state,

wherein open-loop user stations comprise user stations with an unknown channel state, and

wherein the contiguous groups of data subcarriers allocated by a base station based on an index provided by the closed-loop user stations, the index indicating a group of contiguous data subcarriers selected by the closed-loop user stations.

12. The method of claim 1 further comprising determining a number of the data subcarriers of a contiguous group to allocate to each closed-loop user stations based on a coherence bandwidth of a channel associated with each of the closed-loop user stations.

13. The method of claim 1 wherein the downlink subframe comprises a set of pilot subcarriers, and

wherein both the closed-loop user stations and the open-loop user stations use the set of pilot subcarriers for channel estimation for use by the closed-loop and open-loop user stations in processing received data.

14. An apparatus comprising a time-frequency unit allocator to allocate contiguous groups of data subcarriers of a downlink subframe to closed-loop user stations, and to allocate remaining data subcarriers of the downlink subframe to open-loop user stations to increase frequency diversity.

15. The apparatus of claim 14 wherein the downlink subframe comprises a plurality of time-units, and

wherein the time-frequency unit allocator allocates the contiguous groups of the data subcarriers to the closed-loop user stations for each time-unit within the downlink subframe, and allocates the remaining data subcarriers non-contiguously to the open-loop user stations for each time-unit within the downlink subframe.

16. The apparatus of claim 15 wherein the apparatus operates in an orthogonal frequency division multiple access (OFDMA) network,

wherein each time-unit comprises an OFDMA symbol,

wherein the time-frequency unit allocator allocates the same contiguous groups of the data subcarriers to the closed-loop user stations for a plurality of OFDMA symbols, and

wherein the time-frequency unit allocator reallocates the remaining data subcarriers to the open-loop user stations for each OFDMA symbol.

17. The apparatus of claim 15 wherein for each time-unit, the time-frequency unit allocator allocates the contiguous groups of data subcarriers to the closed-loop user stations prior to the allocation of the remaining data subcarriers to the open-loop user stations.

18. The apparatus of claim 14 wherein to allocate the remaining data subcarriers to the open-loop user stations, the time-frequency unit allocator systematically partitions a sequence of remaining contiguous data subcarriers into multiple subsequences, and allocates data subcarriers associated with one of the multiple sequences to the open-loop user stations on a per-sequence basis.

19. The apparatus of claim 15 wherein to reallocates remaining data subcarriers of the downlink subframe to open-loop user stations, the time-frequency unit allocator cyclically shifts the remaining data subcarriers for each one or more time units, and allocates the remaining data subcarriers to the open-loop user stations based on the cyclically shifting.

20. The apparatus of claim 15 wherein to reallocate remaining data subcarriers of the downlink subframe to open-loop user stations, the time-frequency unit allocator renumbers the remaining data subcarriers for each one or more time units, and allocates the remaining data subcarriers to the open-loop user stations based on the renumbering.

21. The apparatus of claim 14 wherein the closed-loop user stations comprise user stations with a known channel state,

wherein the open-loop user stations comprise user stations with an unknown channel state, and

wherein the contiguous groups of data subcarriers are selected for allocation by the time-frequency unit allocator based on channel state information provided by the closed-loop user stations.

22. The apparatus of claim 14 wherein closed-loop user stations comprise user stations with a known channel state,

wherein open-loop user stations comprise user stations with an unknown channel state, and

wherein the contiguous groups of data subcarriers are allocated by the time-frequency unit allocator based on an index provided by the closed-loop user stations, the index indicating a group of contiguous data subcarriers selected by the closed-loop user stations.

23. The apparatus of claim 14 wherein the time-frequency unit allocator determines a number of the data subcarriers of a contiguous group to allocate to each closed-loop user stations based on a coherence bandwidth of a channel associated with each of the closed-loop user stations.

24. The apparatus of claim 14 wherein the downlink subframe comprises a set of pilot subcarriers, and

wherein both the closed-loop user stations and the open-loop user stations use the set of pilot subcarriers for channel estimation for use by the closed-loop and open-loop user stations in processing received data.

25. A base station comprising:

one or more substantially omnidirectional antennas to transmit a downlink subframe to closed-loop user stations and open-loop user stations; and

a time-frequency unit allocator to allocate contiguous groups of data subcarriers of the downlink subframe to the closed-loop user stations, and to allocate remaining data subcarriers of the downlink subframe to the open-loop user stations to increase frequency diversity.

26. The base station of claim 25 wherein the downlink subframe comprises a plurality of time-units, and

wherein the time-frequency unit allocator allocates the contiguous groups of the data subcarriers to the closed-loop user stations for each time-unit within the downlink subframe, and allocates the remaining data subcarriers non-contiguously to the open-loop user stations for each time-unit within the downlink subframe.

27. The base station of claim 26 wherein the base station operations in an orthogonal frequency division multiple access (OFDMA) network,

wherein each time-unit comprises an OFDMA symbol,

wherein the time-frequency unit allocator allocates the same contiguous groups of the data subcarriers to the closed-loop user stations for a plurality of OFDMA symbols, and

wherein the time-frequency unit allocator reallocates the remaining data subcarriers to the open-loop user stations for each OFDMA symbol.

28. A computer-accessible medium that provides instructions to allocate time-frequency units of a downlink subframe, which when accessed, cause a machine to perform operations to:

allocate contiguous groups of data subcarriers of the downlink subframe to closed-loop user stations; and

allocate remaining data subcarriers of the downlink subframe to open-loop user stations to increase frequency diversity.

29. The machine-accessible medium of claim 28 wherein the downlink subframe comprises a plurality of time-units, and

wherein the instructions, when further accessed cause the machine to:

allocate the contiguous groups of the data subcarriers to the closed-loop user stations for each time-unit within the downlink subframe; and

allocate the remaining data subcarriers non-contiguously to the open-loop user stations for each time-unit within the downlink subframe.

30. The machine-accessible medium of claim 28 wherein in an orthogonal frequency division multiple access (OFDMA) network, each time-unit comprises an OFDMA symbol,

wherein the instructions, when further accessed cause the machine to:

allocate the same contiguous groups of the data subcarriers to the closed-loop user stations for a plurality of OFDMA symbols; and

reallocate the remaining data subcarriers to the open-loop user stations for each OFDMA symbol.