Performance of an Aggregation-Based MAC Protocol for High-Data-Rate Ultrawideband Ad Hoc Networks

Ultrawideband (UWB) communication is an emerging technology that promises to provide high data rate communication for wireless personal area networks. One of the critical challenges in UWB system design is the timing acquisition problem, i.e., a receiver needs a relative long time to synchronize with transmitted signals. Clearly, the timing acquisition overhead will significantly limit the throughput of high data rate UWB ad hoc networks. To resolve the timing acquisition problem, the authors proposed a general framework for medium access control (MAC) protocols in their previous work (K. Lu, D. Wu, and Y. Fang, "A novel framework for medium access control in ultra-wideband ad hoc networks," Dynamics of Continuous, Discrete and Impulsive Systems (Series B), vol. 12, no. 3, pp. 427-441, Jun. 2005); under the framework, a transmitting node can aggregate multiple upper layer packets into a burst frame at the MAC layer. In this paper, the authors propose an aggregation-based MAC protocol within the framework. Besides packet aggregation, they also design a novel retransmission scheme which is suitable for error-prone wireless environment, in which only the packets that encounter transmission errors will be retransmitted. To evaluate the performance of the protocol, they develop a three-dimensional Markov chain model for the saturated throughput performance. In addition, they also analyze the end-to-end delay performance through simulation. Extensive numerical and simulation results show that, compared to existing MAC protocols, in which upper layer packets are transmitted one by one, the proposed protocol can drastically reduce the timing acquisition overhead. Consequently, both the throughput and the end-to-end delay performance can be significantly improved