Analysis of Delayed Acknowledgment Scheme with Packet Fragmentation of UWB-Based WPAN

Delayed acknowledgment (Dly-ACK) and packet fragmentation are link-layer policies for ultra-wideband (UWB) based wireless personal area networks (WPANs) to improve the channel utilization, defined in both the IEEE 802.15.3a and ECMA-368 standards. On the other hand, the shadowing effect caused by people moving between the transmitter and receiver may severely degrade the received signal power and thus introduce channel variation. In this paper, we develop an analytical framework for studying the performance of the Dly-ACK and fragmentation over UWB fading channels. A Markov model is used to capture the time-variation of the UWB shadowing channel. The distribution of transmission delay of fragmented packets and the queuing behavior of the sender's buffer are derived. The system performance of packet delay and loss are obtained. Validated by simulations, the analytical results provide important insights and guidelines for better supporting high data rate, delay sensitive traffic in UWB-based WPANs.