Cooperative Spatial Modulation for Cellular Networks

Abstract

Spatial modulation (SM) is a unique single-stream, multiple-input multiple-output (MIMO) transmission technique. One key property of the SM is that a single transmit antenna is activated at any given time, which completely avoids inter-channel interference in a single-user scenario. In the context of multi-user cellular networks, inter-cell interference (ICI) mitigation becomes the main challenge for the SM. Network MIMO is a technique that employs precoding to enable ICI cancellation among neighbouring cells. However, the cell-edge users might still experience a high level of the ICI due to the significant channel attenuation. In this paper, we propose a novel cooperative scheme based on the SM, named cooperative SM (CoSM). The basic concept is to reschedule the transmit antennas of multiple base stations for multiple co-channel users, so as to maximize the antenna diversity gain. Unlike the traditional antenna selection for a single user, the involvement of multiple users might cause conflict due to the selection of the same antenna. An antenna rescheduling scheme (ARS) is thus proposed to address this issue. The performance of the ARS is theoretically analyzed, and closed-form expressions are derived for the probability distribution of the received SNR. Also, a novel three-tier cellular architecture is proposed to accommodate the CoSM within the context of the network MIMO. Results show that the CoSM can improve signal-to-interference-plus-noise ratio by up to 4 dB over the network MIMO. In addition, compared with spatial multiplexing using the same ARS, the CoSM can halve the energy consumption while achieving the same bit error rate.