Efficient large-scale multiple input multiple output communications
Methods and systems for beam forming include measuring channel state information for a set of different codebook entries. An angle of arrival (AoA) distribution is determined with a processor using compressive testing based on the measured channel state information. A set of phase shift values is determined based on the determined AoA to perform phased array beamforming.
1. A method for beam forming, implemented in a user equipment used in a communication system, the method comprising:
measuring channel state information for each of a set of different codebook entries;
determining an angle of arrival (AoA) distribution with a processor using compressive sensing based on the measured channel state information;
determining a set of phase shift values based on the determined AoA; and
controlling a set of phase shifters in accordance with respective phase shift values of the determined set of phase shift values to perform phased array beamforming.
2. The method of claim 1 , wherein the CSI is related to the AoA by an inverse discrete space Fourier transform.
3. The method of claim 2 , wherein determining the AoA comprises solving:
â l k (θ)=arg min ∥ a l k (θ)∥ 2
s. t. ĥ s,c (1) =b (v) F (−1) a l k (θ), 1 ≦v≦V
where a l k (θ) is an arbitrary distribution of signal energy given the incident angle θ of the signal, â l k (θ) represents a specific distribution of energy, ĥ s,c (1) is a CSI measurement taken with codebook entries b (1) , . . . , b (V) , where 1≦v≦V and V is a number of total CSI measurements, and where F −1 is an inverse discreet space Fourier transform matrix.
4. The method of claim 1 , wherein a set of phase shift values is selected to maximize signal-to-leakage-power ratio (SLR) between a phased-array antenna and a respective user.
5. The method of claim 4 , wherein the SLR is measured as a ratio between the AoA distribution from the phased-array antenna to the respective user and a sum of AoA distributions from the phased-array antenna and concurrently active users in adjacent cells.
6. A base station used in a communications system, comprising:
a channel state information module configured to measure channel state information for each of a set of different codebook entries;
an angle of arrival (AoA) module comprising a processor configured to determine an AoA distribution using compressive sensing based on the measured channel state information; and
a phase control module configured to determine a set of phase shift values based on the determined AoA to perform phased array beamforming.
7. The system of claim 6 , wherein the CSI is related to the AoA by an inverse discrete space Fourier transform.
8. The system of claim 7 , wherein determining the AoA comprises solving:
â l k (θ)=arg min ∥ a l k (θ)∥ 2
s. t. ĥ s,c (1) =b (v) F (−1) a l k (θ), 1 ≦v≦V
where a l k (θ) is an arbitrary distribution of signal energy given the incident angle θ of the signal, â l k (θ) represents a specific distribution of energy, ĥ s,c (1) is a CSI measurement taken with codebook entries b (1) , . . . , b (V) , where 1≦v≦V and V is a number of total CSI measurements, and where F −1 is an inverse discreet space Fourier transform matrix.
9. The system of claim 6 , wherein the phase control module is further configured to select a set of phase shift values to maximize signal-to-leakage-power ratio (SLR) between a phased-array antenna and a respective user.
10. The system of claim 9 , wherein the SLR is measured as a ratio between the AoA distribution from the phased-array antenna to the respective user and a sum of AoA distributions from the phased-array antenna and concurrently active users in adjacent cells.