RF Isolated Real-Time Multipath Testbed for Performance Analysis of WLANs

Real-time performance evaluation of WLANs is an extremely challenging topic. The major drawback of real-time performance analysis in actual network installations is a lack of repeatability due to uncontrollable interference and propagation complexities, which are caused by unpredictable variations in the propagation channel. This stresses a need for an RF test system that provides isolation from interfering sources while simulating a real-time channel, thereby creating a realistic and controllable radio propagation test environment. In this paper we introduce a novel testbed for real-time laboratory performance evaluation of WLANs utilizing an RF isolated test system (Azimuthtrade Systems 801W) for isolation from interference and a real-time multipath channel simulator (Elektrobit PROPSimtradeC8) for channel emulation. A software protocol analyzer (WildPackets Airopeek NX) is used to capture data packets in the testbed. The relationship between the throughput and received power, under controlled propagation and interference conditions, is analyzed. We present practical models describing the throughput/power relationship for multirate IEEE 802.11b/g devices in different propagation conditions.