MULTI-SITE MIMO COOPERATION IN CELLULAR NETWORKS

• US 20110194540A1
• Filed: 09/21/2010
• Published: 08/11/2011
• Est. Priority Date: 09/22/2008
• Status: Active Grant

• Current Assignee: Hua Xu, Jianglei Ma, Mohammad Hadi Baligh
• Original Assignee: Blackberry Limited
• Inventors: Xu, Hua, Ma, Jianglei, Baligh, Mohammadhadi
• Granted Patent: US 10,615,851 B2
• Time in Patent Office: Days
• US Class Current: 370/337
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0669 using different channel coding between antennas space-time coding H04L1/0618
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0689 using different transmission schemes, at least one of them being a diversity transmission scheme
• CPC Class Codes: H04B 7/12 Frequency diversity
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 1/0625 Transmitter arrangements
• CPC Class Codes: H04L 1/0656 Cyclotomic systems, e.g. Bell Labs Layered Space-Time [BLAST]
• CPC Class Codes: H04L 1/0668 Orthogonal systems, e.g. using Alamouti codes
• CPC Class Codes: H04L 5/0007 the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04W 72/542 using measured or perceived quality

Abstract

A method of serving a given data stream to a target mobile terminal, in a cellular communications network that includes a plurality of transmitting sites wherein each transmitting site including at least one antenna, is provided. The method includes designating at least two of the plurality of transmitting sites as cooperating sites; assigning tones to each transmitting site from a sub-band associated with the cooperating sites; dividing the data stream into at least two sub-data streams, each of the sub-data streams for transmission over selected tones; and interlacing tones of the cooperating sites in accordance with a selected one of a time switching and a frequency switching transmit diversity technique. Other techniques for multi-site MIMO cooperation are also provided.

Claims

1. In a cellular communications network comprising a plurality of transmitting sites wherein each transmitting site comprises at least one antenna, a method of serving a given data stream to a target mobile terminal, comprising:

designating at least two of said plurality of transmitting sites as cooperating sites;

assigning tones to each transmitting site from a sub-band associated with the cooperating sites;

dividing said data stream into at least two sub-data streams, each of said sub-data streams for transmission over selected tones; and

interlacing tones of said cooperating sites in accordance with a selected one of a time switching and a frequency switching transmit diversity technique.

2. The method of claim 1 wherein said cooperating sites comprise at least two of:

at least one base station and at least one relay.

3. The method of claim 1 wherein said interlacing in accordance with a time switching transmit diversity scheme comprises interlacing said tones in the time domain.

4. The method of claim 1 wherein said interlacing in accordance with a frequency switching transmit diversity scheme comprises interlacing said tones in the frequency domain.

5. The method of claim 1 wherein each said cooperating sites comprises at least two antennas and antennas at each said cooperating site transmit in accordance with a selected one of a transmit diversity or spatial multiplexing technique.

6. The method of claim 5 wherein said transmit diversity technique comprises a space-time-frequency transmit diversity.

7. The method of claim 5 wherein said transmit diversity technique comprises an Alamouti coding algorithm.

8. In a cellular communications network comprising a plurality of transmitting sites, a method of serving a data stream to a target mobile terminal, comprising:

designating a first transmitting site and a second transmitting site as cooperating sites;

at said first transmitting site, transmitting said data stream to said mobile terminal in accordance with a beamforming technique; and

at said second transmitting site, transmitting said data stream to said mobile terminal in accordance with a beamforming technique wherein said beam transmitted by said second transmitting site is adjusted to result in constructive addition of beams arriving at said target mobile terminal from said first and said second transmitting sites.

9. The method of claim 8 wherein one of said first and second transmitting sites comprises an antenna array and wherein said transmitting comprises transmitting the same data stream from each antenna of said antenna array.

10. The method of claim 9 further comprising:

at a primary antenna of said array,

receiving channel quality information (CQI) feedback from said target mobile terminal;

responsive to said CQI feedback, providing an indicator of a linear phase adjustment to each other antenna of said array; and

phase shifting beams transmitted by each of said other antennas by said indicated amount to thereby result in constructive addition of beams arriving at said target mobile terminal from said array.

11. The method of claim 10 wherein said phase shifting comprises shifting components of said data stream only at selected frequencies.

12. The method of claim 11 wherein said phase shifting comprises codebook phase correction.

13. The method of claim 12 wherein said applying said phase shifting comprises, for nomadic target mobile terminals, opportunistic phase correction.

14. The method of claim 13 wherein said opportunistic phase correction comprises applying random phase sequences at each antenna and based on received CQI feedback, selecting the best phase combination.

15. The method of claim 8 wherein one of said first and second transmitting sites is a MIMO site and wherein said beam beamed by said MIMO site is formed using precoding.

16. The method of claim 15 further comprising selecting a precoder based on received CQI feedback.

17. The method of claim 10 wherein said indicator comprises an indicator of a timing mismatch of arriving beams at said target mobile terminal.

18. The method of claim 17 wherein said indicator of said timing mismatch is generated using a selected one of arrival time estimation and channel estimation techniques.

19. In a cellular communications network comprising a plurality of transmitting sites, a method of serving a target mobile terminal, comprising:

designating at least two of said plurality of transmitting sites as a cooperating site;

designating one transmitting site of said cooperating site as a serving site;

designating a non-serving transmitting site as a phase reference site;

assigning a fixed precoder to said phase reference site;

only at said serving site,

receiving an indicator of a precoder for phase correction; and

encoding transmissions to said target mobile device using said indicated precoder.

20. The method of claim 19 wherein said cooperating site comprises two transmitting sites, and wherein said precoder is selected from a two-transmitter constant amplitude codebook.

21. The method of claim 19 wherein said cooperating site comprises M transmitting sites wherein M is greater than two, and wherein said said precoder is selected from a M-transmitter constant amplitude codebook.

22. The method of claim 19 wherein said precoder is selected from a virtual antenna precoder codebook.

23. The method of claim 22 wherein said selected virtual antenna precoder is a virtual antenna closed-loop precoder.

24. In a cellular communications network comprising a plurality of transmitting sites, a method of serving a target mobile terminal, comprising:

designating two unique subsets of transmitting sites as a first and second cooperating site;

employing closed loop techniques within each cooperating site; and

employing open loop cooperation techniques between cooperating sites.

25. The method of claim 24 wherein said open loop cooperation techniques comprise transmitting the same data stream from said first cooperating site and said second cooperating site in accordance with a transmit diversity technique.

26. The method of claim 25 wherein said transmit diversity technique is a selected one of frequency-switching or Alamouti.

27. The method of claim 24 wherein said open loop cooperation techniques comprise transmitting different data streams from said first cooperating site and said second cooperating site in accordance with a spatial multiplexing technique.

28. The method of claim 24 wherein said closed loop techniques within each cooperating site comprises a selected one of MIMO channel coefficients, MIMO precoders and beamforming.