Adaptive beam tracking for interference alignment in time-varying mimo interference channels: Conjugate gradient approach

Abstract

In this thesis, a new way of beam design for interference alignment(IA) in time-varying multiuser multi-input and multi-output(MIMO) interference channels is proposed. In the past work, the linear formulation approach for interference alignment is proposed. Based on this approach, this thesis presents an adaptive algorithm for interference-aligning beam tracking in time-varying MIMO interference channels. This algorithm contains two main parts. The first one is constructing the channel information matrix with dummy variables which is already proposed in [1]. The other one is constructing beamforming vector for IA with conjugate gradient approach. It will be shown that obtaining the interference-aligning beam vector is equivalent to minimizing a certain Rayleigh quotient. With numerical results, stability of the proposed algorithm is shown in static channel case. Also the sum rate and the complexity of this algorithm is shown. By comparing with other methods, this thesis asserts that the proposed algorithm is more practical and especially more powerful in terms of the complexity than other methods.