TY - GEN

T1 - Beamforming techniques for single-beam MIMO interference networks

AU - Schmidt, David A.

AU - Utschick, Wolfgang

AU - Honig, Michael L.

PY - 2010

Y1 - 2010

N2 - We consider the joint optimization of beamformers and linear receivers in a MIMO interference network. Each transmitter transmits a single beam corresponding to a rankone precoder. When the number of users K is greater than the number of antennas at each terminal N, the maximum degrees of freedom is achieved via spatial interference alignment. Interference alignment is feasible for up to K = 2N-1 users, in which case there is a finite number of solutions to the alignment conditions. This number of solutions increases rapidly with N, and the solutions depend only on the cross-channel coefficients (i. e., they are independent of the direct channels). To maximize the achievable sum rate at high SNRs we therefore wish to select an aligned solution which is best matched to the direct channels. We evaluate the performance of this scheme for large K and N, assuming that the solution is the best out of a random subset of aligned solutions. We then compare numerically this performance with the performance of previously proposed numerical (e. g., forward-backward) techniques for optimizing beams, and a new technique which tracks the local optimum as the SNR is incrementally increased, similar to a homotopy method for improving convergence properties. We observe that the incremental technique typically achieves better performance than the previously proposed methods.

AB - We consider the joint optimization of beamformers and linear receivers in a MIMO interference network. Each transmitter transmits a single beam corresponding to a rankone precoder. When the number of users K is greater than the number of antennas at each terminal N, the maximum degrees of freedom is achieved via spatial interference alignment. Interference alignment is feasible for up to K = 2N-1 users, in which case there is a finite number of solutions to the alignment conditions. This number of solutions increases rapidly with N, and the solutions depend only on the cross-channel coefficients (i. e., they are independent of the direct channels). To maximize the achievable sum rate at high SNRs we therefore wish to select an aligned solution which is best matched to the direct channels. We evaluate the performance of this scheme for large K and N, assuming that the solution is the best out of a random subset of aligned solutions. We then compare numerically this performance with the performance of previously proposed numerical (e. g., forward-backward) techniques for optimizing beams, and a new technique which tracks the local optimum as the SNR is incrementally increased, similar to a homotopy method for improving convergence properties. We observe that the incremental technique typically achieves better performance than the previously proposed methods.

UR - http://www.scopus.com/inward/record.url?scp=79952412555&partnerID=8YFLogxK

U2 - 10.1109/ALLERTON.2010.5707048

DO - 10.1109/ALLERTON.2010.5707048

M3 - Conference contribution

AN - SCOPUS:79952412555

SN - 9781424482146

T3 - 2010 48th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2010

SP - 1182

EP - 1187

BT - 2010 48th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2010

T2 - 48th Annual Allerton Conference on Communication, Control, and Computing, Allerton 2010

Y2 - 29 September 2010 through 1 October 2010

ER -