Maximizing SINR in DL MU-MIMO system on SDP algorithm

In this paper a semi-definite programming (SDP) algorithm is considered for solving a non-convex quadratic optimization problem with inequality constraints. This algorithm is used for a model of maximizing signal to interference and noise ratio (SINR) with the constraint of each user's transmitted power in the downlink multiuser multiple-input and multiple-output (DL MU-MIMO) system that can get the optimal value of each user's SINR. Compared with the block diagonalization (BD) method and the Generalized Zero-Forcing Channel Inversion (GZI) method, the SDP algorithm shows better performance.

I. Introduction

MU-MIMO technology, a critical part of wireless communications such as IEEE 802.11n (Wi-Fi), LTE, 3GPP Long Term Evolution, WiMAX and HSPA+., can be divided into two main models. One of them is maximizing SINR with the constraint of each user's transmitted power in the downlink system[1]; the other is minimizing the transmitted power with the constraint of SINR in the downlink system. Comparing these two models, the first one, maximizing SINR, has an advantage on binding transmitted power and saving energy. In the rapid development of technology, the pursuit of energy conservation is also a target.