Traditional wireless cellular networks support voice or other constant-bit-rate connections. Under these conditions, fixed bandwidth allocation schemes have been successfully used to multiplex multiple users in the same cell while providing protection from multi-user interference. However, future wireless networks will need to accommodate multimedia sources that are bursty in nature and generate variable-bit-rate traffic. The goal of this project is to develop ALLIANCES (ALLow Improved Access in the Network via Cooperation and Energy Savings), a high-throughput medium access scheme for wireless networks that is suitable for bursty sources.
The wireless network is viewed as a spatially distributed antenna, with antenna elements linked via the unreliable wireless channel. When there is a collision, the packets involved in the collision are saved in a buffer. In the slots following the collision, a set of nodes, designated as relays, form an alliance and bounce off the signal that they received during the collision slot. By processing the originally collided packets and the signals forwarded by the relays, the destination node can recover the original packets. The spatial diversity introduced via the cooperative relaying enables one to effectively deal with the wireless channel without any bandwidth expansion or additional antenna hardware. ALLIANCES maintains the benefits of ALOHA systems in the sense that all nodes share access to media resources efficiently and without extra scheduling overhead, and enables efficient use of network power. Due to the importance of wireless communication in today's society, any improvement in throughput and energy savings is a worthwhile endeavor.
