Combining for Cooperative WLANs - A Reality Check Based on Prototype Measurements

Many cooperative relaying systems combine signals received over multiple paths. For this task, in literature usually maximum ratio combining (MRC), or one of its derivatives, is assumed. We show that these complex techniques are not required in wireless local area network (WLAN) scenarios with slowly fading channels. Instead, simply selecting the "best" decoded packet achieves similar performance. This packet selection combining (PSC) is more practical than MRC as it is independent on channel-knowledge, does not limit the choice of the modulation scheme, and avoids complex physical layer (PHY) implementation. Our real-time transceiver prototype demonstrates PSC's feasibility; measurements in an indoor scenario show its high performance and validate our theoretical results.