Method and System for Generating Antenna Selection Signals in Wireless Networks

• US 20080232325A1
• Filed: 12/10/2007
• Published: 09/25/2008
• Est. Priority Date: 03/22/2007
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Original Assignee: Mitsubishi Electric Research Laboratories, Inc. (Mitsubishi Electric Corporation)
• Inventors: Bala, Erdem, Mehta, Neelesh B., Zhange, Jinyun
• Granted Patent: US 8,824,420 B2
• Time in Patent Office: Days
• US Class Current: 370/332
• CPC Class Codes: H04B 7/061 using feedback from receiving side
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04L 25/0204 of multiple channels
• CPC Class Codes: H04L 25/0228 with direct estimation from sounding signals
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

A method and system generating signal to select a subset of antennas from a set of antennas to transmit user data in a wireless communication system. User data are transmitted during a first transmission time intervals (TTI) using a first subset of antennas. Pilot tones are transmitted during a second TTI using a second subset of antennas. Corresponding channels are estimated for the first subset of antennas and the second subset of antennas from the user data and the pilot tones. Then, based on the estimating, an optimal subset of antenna is selected from the first subset of antennas and the second subset of antennas to transmit the user data during a sequent TTI, and in which the selecting is performed adaptively.

Claims

1. A method for generating antenna selection (AS) signals in a wireless communication network, comprising:

transmitting the AS signals by the user equipment (UE) using a first subset of a set of available antennas of the UE;

transmitting the AS selection signals by the UE using a second subset of antennas of the set of available antennas of the UE;

estimating channels in a base station (BS) for the first subset of antennas and the second subset of antennas from the AS signals; and

selecting an optimal subset of antennas in the BS from the first subset of antennas and the second subset of antennas based on the estimated channels to transmit user data to the BS.

2. The method of claim 1, in which the AS signals can be selected from user data signals, data modulation reference signals, pilot tones, channel quality indicator (CQI) signals, and broadband sounding reference signals.

3. The method of claim 2, in which the transmitting, estimating and selecting are performed during a single transmit time interval (TTI).

4. The method of claim 3, in which the TTI comprises a subframe including a plurality of long blocks, a plurality of short blocks, and a plurality of cyclic prefixes separating the long blocks and the short blocks, and the long blocks are used to transmit the user data, and the short blocks are used to transmit the pilot tones.

5. The method of claim 3, in which the TTI comprises a subframe including a plurality of long blocks and a plurality of cyclic prefixes separating the long blocks.

6. The method of claim 1, in which the AS signals use orthogonal frequency division multiplexing.

7. The method of claim 1, in which the BS feeds back information related to the optimal subset of antennas to the UE.

8. The method of claim 1, in which the selecting is periodic.

9. The method of claim 1, in which the selecting is on demand.

10. The method of claim 1, further comprising:

receiving in the UE using information related to the optimal subset of antennas.

11. The method of claim 1, in which the AS signals use frequency division multiplexing.

12. The method of claim 1, in which the AS signals use code division multiplexing in a time division multiplexed manner.

13. The method of claim 1, in which the transmitting, estimating and selecting are performed every second transmit time interval.

14. The method of claim 2, in which the CQI signals are used for joint resource block carrier frequency reassignment and antenna selection.

15. The method of claim 9, in which the on demand selecting is based on signal interference and noise ratio (SINR) estimates.

16. The method of claim 9, in which the on demand selecting is initiated by the UE.

17. The method of claim 9, in which the on demand selecting is initiated by the BS.

18. The method of claim 1, in which the AS signals include antenna selection control information.

19. The method of claim 18, in which the antenna selection control information indicates the subsets of antennas used by the UE to transmit the AS signals.

20. The method of claim 18, in which the antenna selection control information indicates an antenna selection request by the UE.

21. The method of claim 4, in which the UE switches between the subsets of the antennas during one of the cyclic prefixes.

22. The method of claim 1, in which the AS signals are part of a control packet.

23. The method of claim 22, in which the control packet includes an ACK or a NACK.

24. The method of claim 1, in which the UE switches between the subsets of the antennas during a data symbol of the user data.

25. The method of claim 1, in which the subset of antennas that most recently transmitted the user data is a selected antenna subset of the set of available antennas and other antennas of the set of available antennas is an unselected antenna subset, and further comprising:

transmitting the AS signals less frequently with the unselected antenna subset than the selected antenna subset.

26. The method of claim 25, in which the selected antenna subset transmits the AS signal k times for every one time that the unselected antenna subset transmits the AS signal, in which k is greater one.

27. The method of claim 25, in which the AS signal is a broadband sounding reference signal.

28. The method of claim 25, in which the AS signal is a data modulation reference signal.

29. The method of claim 25, in which the BS transmits k to the UE before the UE transmits the AS signals.

30. The method of claim 1, in which the first subset of antennas was used most recently to transmit the user data.

31. A system for generating antenna selection (AS) signals in a wireless communication network, comprising:

user equipment (UE) configured to transmit the AS signals using a first subset of a set of available antennas of the UE and then to transmit the AS signals using a second subset of antennas of the set of available antennas of the UE;

a base station (BS) configured to estimate channels for the first subset of antennas and the second subset of antennas from the AS signals; and

means for selecting an optimal subset of antennas in the BS from the first subset of antennas and the second subset of antennas based on the estimated channels to transmit user data to the BS.

32. The system of claim 31, in which the transmitting, estimating and selecting are performed during a single transmit time interval (TTI).

33. The system of claim 31, in which the BS feeds back information related to the optimal subset of antennas to the UE.