A high performance MIMO detection algorithm for DL MU-MIMO with practical errors in IEEE 802.11ac systems

In this paper, we propose a high performance multiple-input and multiple-output (MIMO) detection algorithm for downlink multiuser MIMO (DL MU-MIMO) with practical errors in IEEE 802.11ac systems. The DL MU-MIMO system using the precoding matrix, which is generated through imperfect channel state information caused by channel estimation error and channel feedback quantization error, has severe performance degradation since each station (STA) receives the desired signal for the STA as well as the interference signal for different STAs. Therefore, the proposed detection algorithm is developed by considering both the desired signal and the interference signal. Using the characteristics of the interference signal, the proposed detection algorithm is performed by additionally detecting several interference symbols. The proposed algorithm has better performance than the conventional algorithm considering only the desired signal. Simulation results show that the coded bit error rate performance of the proposed algorithm was improved in all modulation and coding scheme cases, compared to the conventional algorithm.

I. Introduction

The new standard of wireless local area network (WLAN), called IEEE 802.11ac [1], has recently been published for providing at least 500 Mbps of single station throughput and more than 1 Gbps of multi-station throughput. For this purpose, the new standard has been extended the bandwidth up to 160 MHz, the spatial streams up to , and the modulation order up to 256 QAM. It also has adopted a downlink multi-user multiple-input and multiple-output (DL MU-MIMO) technology [1]–[3]. The DL MU-MIMO technology increases system capacity for multiple stations (STA) by enabling simultaneous transmission from one access point (AP) to multiple STAs. This technology is performed by multiplying the precoding matrix, generated through down-link channel state information (CSI) about each STA, to the transmit signal. Therefore, the DL MU-MIMO necessarily needs downlink CSI feedback about each STA and precoding techniques. Several precoding techniques [4]–[6] for DL MU-MIMO have been intensively studied during recent years. In particular, the channel inversion(CI), the block diagonalization (BD) [4], and the vector perturbation (VP) [6] algorithms are well known.