TECHNIQUES FOR DOWNLINK COORDINATED MULTI-POINT (CoMP) COMMUNICATIONS USING UNLICENSED RADIO FREQUENCY SPECTRUM BAND

• US 20150146680A1
• Filed: 09/30/2014
• Published: 05/28/2015
• Est. Priority Date: 11/25/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Luo, Tao, Chen, Wanshi, Malladi, Durga Prasad, Wei, Yongbin, Bhushan, Naga, Damnjanovic, Aleksandar, Yerramalli, Srinivas, Ji, Tingfang, Gaal, Peter
• Granted Patent: US 9,531,512 B2
• Time in Patent Office: Days
• US Class Current: 370/330
• 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 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0608 Antenna selection according to transmission parameters
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• CPC Class Codes: H04J 11/0053 using co-ordinated multipoint transmission/reception co-ordinated antenna or beam-forming aspects H04B7/022
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 5/0035 Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04W 72/044 based on the type of the allocated resource
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/27 between access points
• CPC Class Codes: H04W 72/563 of the wireless resources
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

Techniques are described for downlink coordinated multi-point (CoMP) procedures for access to a contention-based radio frequency spectrum band. A base station performs a contention procedure, such as a clear channel assessment (CCA) procedure, for access to the radio frequency spectrum band. The base station determines whether contention has been won for a time period, and communicates whether or not contention has been won to other base stations in a CoMP cooperating set. Based on the information exchanged between base stations in the CoMP cooperating set, coordinated communications is initiated to a UE with two or more of the base stations in the CoMP cooperating set.

Claims

1. A method for wireless communications by a base station of a coordinated multi-point (CoMP) cooperating set of base stations in a wireless communications network, comprising:

performing a clear channel assessment (CCA) procedure to contend for access to an unlicensed radio frequency spectrum band;

determining a CCA status that indicates whether contention has been won for a time period; and

communicating the CCA status to one or more other base stations in the CoMP cooperating set.

2. The method of claim 1, wherein performing the CCA procedure comprises:

performing an enhanced clear channel assessment (eCCA) procedure

3. The method of claim 1, further comprising:

initiating CoMP communications with a user equipment (UE) using one or more base stations in the CoMP cooperating set that have a CCA status of winning the contention for the time period.

4. The method of claim 1, further comprising:

receiving one or more CCA status of the one or more other base stations that indicate whether the one or more other base stations have won contention for the time period.

5. The method of claim 4, wherein,

the time period corresponds to a time period for transmission of a radio frame that comprises a plurality of subframes;

and

the communicating and the receiving are performed during a CCA status notification time period of the radio frame.

6. The method of claim 5, wherein initiating CoMP communications is performed after the CCA status notification time period of the radio frame.

7. The method of claim 5, wherein the CCA status notification time period may be determined based at least in part on the nature of the CCA procedure.

8. The method of claim 3, wherein the initiating CoMP communications comprises transmitting, by a base station of the one or more base stations, a control channel to the UE and transmitting, by remaining base stations of the one or more base stations, one or more data channels to the UE.

9. The method of claim 3, wherein the initiating CoMP communications comprises:

initiating dynamic point selection (DPS) communications from the base station to the user equipment (UE) during at least a portion of the time period; and

discontinuing DPS communications from the base station while one of the one or more other base stations perform DPS communications with the UE.

10. The method of claim 9, wherein at least the portion of the time period corresponds to a CCA status notification time period of a radio frame, and wherein discontinuing DPS communications from the base station comprises:

discontinuing wireless transmissions to the UE; and

/or

transmitting to one or more other UEs in order to maintain a transmission bandwidth threshold.

11. The method of claim 9, wherein the portion of the time period corresponds to a time period of a first radio frame, and wherein discontinuing DPS communications from the base station comprises discontinuing transmissions to the UE during a second radio frame:

12. The method of claim 1, further comprising:

transferring a channel state information (CSI) report from the base station to the one or more other base stations in the CoMP cooperating set.

13. The method of claim 12, wherein the CSI report includes a rank indicator (RI) for use by the one or more other base stations in the CoMP cooperating set.

14. The method of claim 13, wherein the RI is for use by the one or more other base stations in the CoMP cooperating set when a subsequent CCA procedure of the base station fails and the one or more other base stations win the contention of the subsequent CCA procedure.

15. The method of claim 1, further comprising:

transferring a reference rank indicator from the base station to the one or more other base stations in the CoMP cooperating set for use by the one or more other base stations when a subsequent CCA procedure of the base station fails and the one or more other base stations win the contention of the subsequent CCA procedure.

16. An apparatus for wireless communications by a base station of a coordinated multi-point (CoMP) cooperating set of base stations in a wireless communications network, comprising:

means for performing a clear channel assessment (CCA) procedure to contend for access to an unlicensed radio frequency spectrum band;

means for determining a CCA status that indicates whether contention has been won for a time period; and

means for communicating the CCA status to one or more other base stations in the CoMP cooperating set.

17. The apparatus of claim 16, further comprising:

means for initiating CoMP communications with a user equipment (UE) using one or more base stations in the CoMP cooperating set that have a CCA status of winning the contention for the time period.

18. The apparatus of claim 16, further comprising:

means for receiving one or more CCA status of the one or more other base stations that indicate whether the one or more other base stations have won contention for the time period.

19. The apparatus of claim 18, wherein,

the time period corresponds to a time period for transmission of a radio frame that comprises a plurality of subframes;

and

the communicating and the receiving are performed during a CCA status notification time period of the radio frame.

20. The apparatus of claim 19, wherein initiating CoMP communications is performed after the CCA status notification time period of the radio frame.

21. The apparatus of claim 17, wherein initiating CoMP communications comprises transmitting, by a base station of the one or more base stations, a control channel to the UE and transmitting, by remaining base stations of the one or more base stations, one or more data channels to the UE.

22. The apparatus of claim 17, wherein initiating CoMP communications comprises:

initiating dynamic point selection (DPS) communications from the base station to the user equipment (UE) during at least a portion of the time period; and

discontinuing DPS communications from the base station while one of the one or more other base stations perform DPS communications with the UE.

23. The apparatus of claim 22, wherein at least the portion of the time period corresponds to a CCA status notification time period a radio frame, and wherein discontinuing DPS communications from the base station comprises:

discontinuing wireless transmissions to the UE; and

/or

transmitting to one or more other UEs in order to maintain a transmission bandwidth threshold.

24. The apparatus of claim 22, wherein the portion of the time period corresponds to a time period of a first radio frame, and wherein discontinuing DPS communications from the base station comprises discontinuing transmissions to the UE during a second radio frame:

25. The apparatus of claim 16, further comprising:

transferring a channel state information (CSI) report from the base station to the one or more other base stations in the CoMP cooperating set.

26. The apparatus of claim 25, wherein the CSI report includes a rank indicator (RI) for use by the one or more other base stations in the CoMP cooperating set.

27. The apparatus of claim 26, wherein the RI is for use by the one or more other base stations in the CoMP cooperating set when a subsequent CCA procedure of the base station fails and the one or more other base stations win the contention of the subsequent CCA procedure.

28. An apparatus for wireless communications by a base station of a coordinated multi-point (CoMP) cooperating set of base stations in a wireless communications network, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to cause the apparatus to;

perform a clear channel assessment (CCA) procedure to contend for access to an unlicensed radio frequency spectrum band;

determine a CCA status that indicates whether contention has been won for a time period; and

communicate the CCA status to one or more other base stations in the CoMP cooperating set.

29. A method for wireless communications by a user equipment in a wireless communications network, comprising:

determining whether one or more base stations in a coordinated multi-point (CoMP) cooperating set have won contention for a time period based at least in part on a clear channel assessment (CCA) procedure for access to an unlicensed radio frequency spectrum band; and

receiving CoMP communications from the one or more base stations in the CoMP cooperating set that have won contention.

30. The method of claim 29, further comprising:

transmitting reference signal measurements to the one or more base stations based on the determination.