Rank Adaptation for an Open Loop Multi-Antenna Mode of Wireless Communication

• US 20090086648A1
• Filed: 08/20/2008
• Published: 04/02/2009
• Est. Priority Date: 10/02/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Wu, Jianming, Baligh, Mohammadhadi, Xu, Hua, Tong, Wen, Ma, Jianglei, Zhu, Peiying, Jia, Ming
• Granted Patent: US 8,948,093 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme

Abstract

To perform rank adaptation for a mobile station in a wireless network, it is determined whether the mobile station is fast moving. In response to determining that the mobile station is fast moving, an open loop multi-antenna mode is selected to perform wireless communication between the mobile station and a base station. Also, selection is made from among plural ranks for the wireless communication according to the open loop multi-antenna mode between the mobile station and the base station.

Claims

1. A method of performing rank adaptation for a mobile station in a wireless network, comprising:

determining a velocity of the mobile station;

in response to determining that the velocity of the mobile station is above the predefined threshold, selecting an open loop multi-antenna mode to perform wireless communication between the mobile station and the base station; and

selecting from among plural ranks for the wireless communication according to the open loop multi-antenna mode between the mobile station and the base station.

2. The method of claim 1, wherein determining the velocity is performed by one of the mobile station and base station.

3. The method of claim 1, further comprising sending, by the mobile station, an indication of the selected rank to the base station, wherein the indication is sent according to a set interval.

4. The method of claim 1, further comprising:

receiving, by the base station from the mobile station an indication of a rank to be used,

wherein selecting from among the plural ranks is based on the received indication.

5. The method of claim 4, wherein receiving the indication of the rank to be used comprises receiving the indication of the rank to be used in association with a report of a wireless channel quality.

6. The method of claim 1, wherein selecting from among the plural ranks comprises selecting from among at least a first rank that employs transmit diversity and a second rank that employs spatial multiplexing.

7. The method of claim 1, further comprising:

receiving, from the mobile station, an identifier for a codeword to use for coding data in wireless communication according to the closed loop multi-antenna mode.

8. The method of claim 1, further comprising:

using, in the open loop multi-antenna mode, a predetermined codeword or a codeword sequence to code data of the wireless communication.

9. The method of claim 1, wherein the predetermined codeword is a predefined codeword in a codebook used for the closed loop multi-antenna transmission mode.

10. The method of claim 1, wherein selecting from among the plural ranks for the wireless communication according to the open loop multi-antenna mode is according to a condition of a wireless channel between the mobile station and base station.

11. The method of claim 10, further comprising:

receiving, by the base station from the mobile station, information relating to long-term signal-to-interference-plus-noise that indicates the wireless channel condition.

12. The method of claim 1, wherein selecting from among the plural ranks for the wireless communication according to the open loop multi-antenna mode comprises selecting a rank greater than rank 1, the method further comprising:

using cyclic delay diversity when the rank selected is greater than rank 1.

13. The method of claim 1, wherein switching between the closed loop multi-antenna mode and the open loop multi-antenna mode is associated with switching between localized channel assignment and diversity channel assignment.

14. A base station comprising:

an interface to perform wireless communication with a mobile station; and

a processor to;

determine whether the mobile station is a high-velocity mobile station;

in response to determining that the mobile station is a high-velocity mobile station, select a multi-antenna mode of communication for downlink data transmitted to the mobile station that does not involve feedback from the mobile station that includes an identifier of a codeword to be used for coding the downlink data; and

apply rank adaptation to select from among a plurality of ranks for the communication of downlink data according to the multi-antenna mode of communication.

15. The base station of claim 14, wherein the selected multi-antenna mode comprises an open loop multi-antenna mode.

16. The base station of claim 15, wherein the processor is to apply a fixed codeword to the downlink data in the open loop multi-antenna mode.

17. The base station of claim 15, wherein the processor is to select a closed loop multi-antenna mode in response to determining that the mobile station is not a high-velocity mobile station.

18. The base station of claim 17, further comprising a higher layer software to signal selection of the open loop multi-antenna mode or closed loop multi-antenna mode.

20. The mobile station of claim 14, wherein the processor is to select a closed loop MIMO mode to perform wireless communication between the mobile station and the base station in response to the velocity not exceeding the predefined threshold.

19. A mobile station comprising:

an interface to perform wireless communication with a base station; and

a processor to;

determine whether a velocity of the mobile station exceeds a predefined threshold;

in response to determining that the velocity of the mobile station exceeds the predefined threshold, select an open loop multiple input multiple output (MIMO) mode to perform wireless communication between the mobile station and the base station; and

use rank adaptation to select from among plural ranks in the wireless communication according to the open loop MIMO mode.