Wireless MIMO switching: network‐coded MMSE relaying and user group selection
Fanggang Wang · Transactions on Emerging Telecommunications Technologies · 2012
ABSTRACT A wireless relay that forms a one‐to‐one mapping from the inputs (uplinks) to the outputs (downlinks) is called a multiple‐input multiple‐output (MIMO) switch. The MIMO switch carries outprecode‐and‐forward, where all users send their signals in the uplink, and then, the MIMO switch precodes the received vector signal for broadcasting in the downlink. Ideally, each user employs a receive filter to recover its desired signal from one other user with no or little interference from other users. We first propose a joint design of the precoder and the receive filters to achieve the minimum‐mean‐ square‐error (MMSE), where network coding technique is incorporated, assuming that full channel state information is available at the relay. When the number of relay antennas is smaller than the number of source users, that is, the users that need to transmit signals, we investigate user group selection algorithms for the proposed MMSE relaying schemes. Our results indicate that the proposed MMSE relaying scheme outperforms the existing zero‐forcing/MMSE schemes. In addition, the results validate the efficiency of the proposed user group selection algorithms. Copyright © 2012 John Wiley & Sons, Ltd.