Challenges in Deploying Steerable Wireless Testbeds ; CU-CS-1058-09

Phased array antennas enable the use of real-time beam-forming and null-steering to further increase control of signal and interference in wireless networks. Understanding the potential of this platform for both wireless mesh networks and single-hop networks is becoming more important as smart antennas begin to emerge in networking standards such as IEEE 802.11n and 802.16. Prior attempts to test non-standard antenna platforms have typically focused around simulations, fixed directional antenna testbeds that are unable to perform null-steering, and small scale temporary setups utilizing 1 or 2 phased array antenna nodes over the span of a few hundred meters. This paper presents the challenges encountered – and solutions developed – in building WART, a permanent, campus-wide testbed for wireless networking with beam-forming antennas. We use affordable commercial off-the-shelf (COTS) hardware as both a measurement apparatus and the system under test. This approach makes it possible to develop and test networking protocols using equipment similar to what may be available operationally, but also presents difficulties beyond those typically encountered with specialized measurement hardware. We show that system-level techniques can adequately overcome those component limitations.