A New Two-Stage Multiuser MIMO Detection Approach with Different Priorities

A new detection scheme for multiuser multiple-input multiple-output (MIMO) systems is analytically presented. In particular, the transmitting users are being categorized in two distinct priority service groups, while they communicate directly with a multi-antenna receiver. The linear zero-forcing scheme is applied in two consecutive detection stages upon the signal reception. In the first stage, the signals of one service group are detected, followed by the second stage including the corresponding detection of the remaining signals. An appropriate switching scheme based on specific transmission quality requirements is utilized prior to the detection so as to allocate the signals of a given service group to the suitable detection stage. The objective is the enhancement of the reception quality for both service groups. The proposed approach can be implemented directly in cognitive radio communication assigning the secondary users to the appropriate service group. The exact outage probability of the considered system is derived in closed form.

I. Introduction

Multiple input-multiple output (MIMO) communication is widely acknowledged as a key technology for achieving high data rates in bandwidth-constrained wireless systems [1]. Recently, there has been a considerable research effort in exploiting the space dimension through spatial multiplexing methods so as to enhance the multiuser diversity; especially in dense communication systems [2]. On another front, cognitive radio (CR) has emerged as one of the most promising technologies to resolve the issue of spectrum scarcity [3], [4]. Due to the complementary benefits of MIMO and CR, hybrid CR MIMO systems are of prime research interest [5].