Beamforming Signaling in a Wireless Network

• US 20130155891A1
• Filed: 12/15/2012
• Published: 06/20/2013
• Est. Priority Date: 12/19/2011
• Status: Active Grant

• Current Assignee: Comcast Cable Communications LLC (Comcast Corporation)
• Original Assignee: Ofinno Technologies, LLC (Ofinno, LLC)
• Inventors: Dinan, Esmael Hejazi
• Granted Patent: US 8,885,569 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04B 7/0417 Feedback systems
• CPC Class Codes: H04B 7/043 using best eigenmode, e.g. beam forming or beam steering
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/046 taking physical layer constraints into account
• CPC Class Codes: H04B 7/0473 taking constraints in layer or codeword to antenna mapping into account
• CPC Class Codes: H04B 7/0478 Special codebook structures directed to feedback optimisation
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04B 7/0626 Channel coefficients, e.g. channel state information [CSI]
• 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 7/0634 Antenna weights or vector/matrix coefficients
• CPC Class Codes: H04B 7/0639 Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection
• CPC Class Codes: H04J 11/0056 Inter-base station aspects
• CPC Class Codes: H04L 25/03955 in combination with downlink estimations, e.g. downlink path losses
• CPC Class Codes: H04L 27/2646 using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
• CPC Class Codes: H04L 5/0023 Time-frequency-space
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/0073 Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 28/0236 radio quality, e.g. interference, losses or delay
• CPC Class Codes: H04W 36/0058 Transmission of hand-off measurement information, e.g. measurement reports
• CPC Class Codes: H04W 36/0064 : of control information between different access points
• CPC Class Codes: H04W 36/0072 : of resource information of target access point
• CPC Class Codes: H04W 36/0094 : Definition of hand-off measurement parameters
• CPC Class Codes: H04W 36/085 : involving beams of access points
• CPC Class Codes: H04W 36/30 : by measured or perceived connection quality data
• CPC Class Codes: H04W 72/044 : based on the type of the allocated resource
• CPC Class Codes: H04W 72/0453 : Resources in frequency domain, e.g. a carrier in FDMA
• CPC Class Codes: H04W 72/046 : the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/20 : Control channels or signalling for resource management
• CPC Class Codes: H04W 72/23 : in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 72/27 : between access points
• CPC Class Codes: H04W 72/541 : using the level of interference
• CPC Class Codes: H04W 74/002 : Transmission of channel access control information
• CPC Class Codes: H04W 88/08 : Access point devices

Abstract

A first base station receives a message from a second base station. The second base station comprises a downlink carrier comprising downlink resource blocks. The message comprises downlink beamforming information element indicating a beamforming codeword employed for a downlink resource block. The first base station obtains channel state input information for a wireless device based on, at least in part, processing the downlink beamforming information. The first base station transmits the channel state input information to the wireless device.

Claims

1. A method comprising:

a) receiving, by a first base station from a second base station, at least one application protocol message, said first base station and said second base station configured to communicate with wireless devices employing a downlink carrier, said downlink carrier comprising a plurality of resource blocks, said at least one application protocol message comprising a downlink beamforming information element for at least one resource block in said downlink carrier, said downlink beamforming information element indicating a second beamforming codeword employed by said second base station for said at least one resource block, said second beamforming codeword included in a second beamforming codebook;

b) computing, by said first base station, a channel state input information element for a wireless device based on, at least in part, processing said downlink beamforming information element; and

c) transmitting, by said first base station, said channel state input information element to said wireless device for computing a precoding matrix indicator; and

d) receiving, by said first base station, a channel state feedback from said wireless device, said channel state feedback comprising said precoding matrix indicator.

2. The method of claim 1, further comprising receiving, by said first base station from said second base station, a plurality of downlink beamforming information elements;

and wherein said computing, by said first base station, said channel state input information element further comprises selecting a subset of said plurality of downlink beamforming information elements.

3. The method of claim 1, further comprising transmitting a plurality of packets to said wireless device, said plurality of packets transmitted employing said precoding matrix indicator.

4. The method of claim 1, further comprising said first base station demodulating, despreading, and decoding the received channel state feedback.

5. The method of claim 1, further comprising receiving from said second base station, beamforming information identifying a cause of substantial inter-cell interference for inclusion in said subset of downlink beamforming information.

6. The method of claim 1, further including defining said second beamforming codebook for a number of layers, said second beamforming codebook comprising a set of codewords having a number of columns or rows equal to or less than said number of layers.

7. The method of claim 6, further comprising constructing codewords for a smaller number of layers employing a subset of columns or rows of said original codewords.

8. The method of claim 7, further comprising indicating a rank of said smaller number of layers equal to a rank indicator field in said channel state feedback received from said wireless device.

9. A method comprising:

a) receiving, by a wireless device, a control message from a first base station, said control message comprising;

i) an identifier of a second base station in said plurality of base stations; and

ii) a channel state input information element based, at least in part, on a downlink beamforming information element received by said first base station from a second base station, said downlink beamforming information element indicating a beamforming codeword employed by said second base station for at least one downlink resource block;

b) measuring, by said wireless device, reference signals received from said second base station;

c) processing, by said wireless device, said measured reference signals based, at least in part, on said channel state input information element to compute a precoding matrix indicator; and

d) transmitting, by said wireless device, channel state information comprising said precoding matrix indicator to said first base station.

10. The method of claim 9, wherein said processing of said measured reference signals comprises multiplying measured reference signal by at least one codeword in said channel state input information.

11. The method of claim 9, wherein said channel state input information element comprises a codebook subset restriction bitmap parameter.

12. The method of claim 11, further comprising said wireless device selecting a precoding matrix indicator from a subset of precoding codebook indicated by said codebook subset restriction bitmap parameter.

13. The method of claim 9, wherein said processing of said measured reference signals further comprises multiplying a measured reference signal by at least one codeword in said downlink beamforming information element.

14. The method of claim 9, further comprising calculating said precoding matrix indicator to reduce downlink inter-cell interference.

15. The method of claim 9, further comprising selecting said precoding matrix indicator from a plurality of predetermined precoding matrix indicators.

16. The method of claim 9, further comprising computing said precoding matrix indicator for a sub-band of said downlink carrier.

17. The method of claim 9, wherein said said precoding matrix indicator is computed employing a minimum mean squared error criterion.

18. A wireless device comprising:

a) one or more communication interfaces;

b) one or more processors; and

c) memory storing instructions that, when executed, cause said wireless device to;

i) receive from a first base station, a channel state input information element based, at least in part, on a downlink beamforming information element received by said first base station from a second base station, said downlink beamforming information element indicating a beamforming codeword employed by said second base station for at least one downlink resource block;

ii) compute a precoding matrix indicator employing said channel state input information element; and

iii) transmit channel state information comprising said precoding matrix indicator to said first base station.

19. The wireless device of claim 18, wherein said precoding matrix indicator is computed employing a zero-forcing criterion.

20. The wireless device of claim 18, wherein said said precoding matrix indicator is computed employing a minimum mean squared error criterion.