Evaluation of 802.11a for streaming data in ad-hoc networks

Advances in communication and processing have made ad-hoc networks of wireless devices a reality. One application is home entertainment systems where multiple Home-to-Home (H20) devices collaborate as peers to stream audio and video clips to a household. In this study, we investigate the feasibility of IEEE 802.11a protocol in combination with both TCP and UDP to realize a H20 device. Challenges include lossy connections, unfair allocation of bandwidth between multiple simultaneous transmissions, and the exposed node limitation [22], [19], [13], [4]. Our primary contribution is an empirical study of 802.11a to quantify these factors and their significance. Our multi-dimensional experimental design consists of the following axes: distance between participating devices, number of intermediate H20 devices used to route a stream from a producing H20 device to a consuming H2O device, and simultaneous number of active streams in the same radio range. Both operating system and application level routing were considered_ Obtained results demonstrate the following lessons. First, with a multi-hop UDP transmission, in the absence of congestion control, transient bottlenecks result in a high loss rate. Hence, a transport protocol with congestion control is essential for streaming of continuous media within a H2O cloud. Second, 802.11a does not drop TCP connections in the presence of many competing transmissions (802.11b drops connections [22]). Third, we observed fairness when transmitting several hundred Megabytes (MB) of data, among multiple competing 1- hop TCP and UDP flows. Fourth, while there is unfair allocation of bandwidth with an exposed node, the observed bandwidths are sufficient to stream a high-quality video clip (with a 4 Mbps display bandwidth requirement). These results indicate streaming of data is feasible with an ad-hoc network of wireless devices employing the 80211a protocol.