Apparatus and methods for transmission and reception of data in multi-antenna systems

• US 20090268675A1
• Filed: 04/28/2008
• Published: 10/29/2009
• Est. Priority Date: 04/28/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Choi, Hyung-Nam
• Granted Patent: US 8,155,063 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas
• CPC Class Codes: H04B 7/0413 MIMO systems
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0032 Distributed allocation, i.e. involving a plurality of allocating devices, each making partial allocation
• CPC Class Codes: H04L 5/0037 Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0064 Rate requirement of the data, e.g. scalable bandwidth, data priority
• CPC Class Codes: H04L 5/0092 Indication of how the channel is divided
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Methods and apparatus adapted to address asymmetric conditions in a multi-antenna system. In one embodiment, the multi-antenna system comprises a wireless (e.g., 3G cellular) multiple-input, multiple-output (MIMO) system, and the methods and apparatus efficiently utilize transmitter and receiver resources based at least in part on a detected asymmetric condition. If an asymmetric condition is detected by the transmitter on any given data stream, the transmitter can decide to utilize only a subset of the available resources for that stream. Accordingly, the signal processing resources for that data stream are adapted to mirror the reduction in resources that are necessary for transmission. The transmitter signals the receiver that it will only be using a subset of the resources available, and the receiver adapts its operation according to the signaling data it receives. The multi-antenna system can therefore reduce power consumption as well as increasing spectral efficiency on the network.

Claims

1. A method for optimizing at least one resource associated with a multi-antenna transmission system comprising a transmitter, a receiver, and a plurality of data streams, each of said plurality of data streams comprising a resource, the method comprising:

detecting an asymmetric condition in one of said plurality of data streams;

allocating a subset of the resource for at least one of said plurality of data streams; and

transmitting a message to said receiver, said message comprising information indicative of said subset of the resource.

2. The method of claim 1, wherein said system comprises a 3G cellular system, said transmitter comprises a base station, and said receiver comprises a substantially portable user device.

3. The method of claim 1, wherein said system comprises a 3G cellular system, said receiver comprises a base station, and said transmitter comprises a substantially portable user device.

4. The method of claim 1, wherein said system includes a plurality of antennas comprising a multi-input, multi-output (MIMO) system.

5. The method of claim 1, wherein said transmitter is adapted to transmit at least one of said streams using orthogonal frequency division multiplexing (OFDM).

6. The method of claim 1, wherein said resource comprises a time-frequency resource.

7. The method of claim 1, wherein said resource comprises a Fast Fourier Transform (FFT) or Inverse Fast Fourier Transform (IFFT) processing resource.

8. An apparatus for optimizing resources in a multi-antenna transmission system, comprising:

a processing device;

a plurality of transmitting antennas; and

a storage device in signal communication with said processing device, said storage device comprising a computer program having a plurality of instructions that when executed by said processing device;

detect an asymmetric condition in one of a plurality of data streams to be transmitted over said plurality of transmitting antennas, each of said plurality of data streams comprising a time-frequency resource;

allocate a subset of the resource of at least one of said plurality of data streams for one of said plurality of transmitting antennas; and

generate a message to be transmitted over at least one of said plurality of transmitting antennas, said message comprising information indicative of said allocation of said subset of the resource.

9. The apparatus of claim 8, wherein said apparatus comprises a base station within a cellular system.

10. The apparatus of claim 8, wherein said apparatus comprises a mobile user device adapted for use within a cellular system.

11. The apparatus of claim 8, wherein said plurality of antennas comprises a multi-input, multi-output (MIMO) system.

12. A computer readable apparatus having a storage medium, said medium adapted to store a computer program comprising instructions which, when executed:

detect an asymmetric condition in one of a plurality of data streams to be transmitted over a plurality of transmitting antennas, each of said plurality of data streams having a default resource allocation associated therewith;

change the default allocation so as to reallocate a subset of the resource of at least one of said plurality of data streams; and

generate a message to be transmitted over at least one of said plurality of transmitting antennas, said message comprising information indicative of said reallocation of said subset of the resource.

13. A multi-antenna transmission system comprising a base station and a user device, said base station and said user device capable of communicating via a plurality of data streams, said multi-antenna transmission system operating according to the method comprising:

detecting an asymmetric condition in one of said plurality of data streams on said base station, each of said plurality of data streams comprising a default resource;

allocating a subset of the default resource for at least one of said plurality of data streams; and

transmitting a signaling message to said user device, said signaling message comprising information indicative of said allocation subset of the default resource.

14. A method of operating a transmitting device within a wireless system so as to provide at least one of reduced power consumption and increased spectral efficiency, said transmitting device having a plurality of antennas, the method comprising:

receiving a plurality of data input streams;

identifying a data rate asymmetry between at least two of said input streams; and

reallocating time-frequency resources based at least in part on said identified data rate asymmetry;

wherein said reallocation of said resources substantially provides said at least one of reduced power consumption and increased spectral efficiency as compared to an allocation of said resources before said reallocation.

15. For use in a wireless communications network, apparatus adapted to:

determine the amount of data to be transmitted for an upcoming transmission period for a first data stream and a second data stream, said amount of data for said second stream being less than said amount of data for said first stream at least during said period;

determine a first number of subcarriers needed to carry the data of said first stream during said period;

determine a second number of subcarriers needed to carry the data of said second stream during said period, said second number being a subset of the first number;

use said first number of said subcarriers for transmission of said first stream; and

use said second number of subcarriers for transmission of said second data stream.

16. The apparatus of claim 15, wherein said first and second subcarriers are part of an orthogonal frequency division multiplexing (OFDM) processing unit.

17. The apparatus of claim 15, wherein said first and second numbers of subcarriers are part of respective orthogonal frequency division multiplexing (OFDM) processing units.

18. The apparatus of claim 17, wherein said use of said second number of subcarriers comprises passing modulation symbols to only a subset of a total number of inputs on an Inverse Fast Fourier Transform (IFFT) process, while the remainder of said total number of inputs remain unused.

19. The apparatus of claim 18, wherein said apparatus is further adapted to signal to a single user device in wireless communication with said apparatus that said first data stream is to use said first number of subcarriers, and said second data stream is to use said second number of subcarriers.

20. The apparatus of claim 18, wherein said apparatus is further adapted to signal to a first user device in wireless communication with said apparatus that said first data stream is to use said first number of subcarriers, and to signal to a second user device in wireless communication with said apparatus that said second data stream is to use said second number of subcarriers.

21. The apparatus of claim 20, wherein said signaling to said first and second user devices further identifies the specific subcarriers to be used for each of said first and second data streams, respectively.

22. The apparatus of claim 15, wherein said apparatus comprises a base station.

23. A method of doing business within a wireless network having a plurality of subscribers, the method comprising:

providing a first subset of said subscribers with first user devices having a first time-frequency resource allocation scheme, said first user devices having associated therewith a first fee or cost; and

providing a second subset of said subscribers with second user devices having a second time-frequency resource allocation scheme, said second user devices having associated therewith a second fee or cost, said second fee or cost.

24. The method of claim 23, wherein said second fee or cost is greater than said first fee or cost, and said second user devices are more battery power-efficient than said first user devices, said greater battery power-efficiency being related at least in part to said second time-frequency resource allocation scheme.

25. The method of claim 24, wherein said second time-frequency resource allocation scheme comprises:

determining an asymmetry in the time-frequency resource requirements of two data streams to be transmitted by one of said second user devices; and

allocating subcarriers within an OFDM modulator so as to avoid unnecessary use of at least some of said subcarriers and processing resources associated therewith.