A real time transport scheme for wireless multimedia communications

In wireless communications systems, a mobile station is typically equipped with limited processing capability and buffer space for transmitting and receiving. The radio link is usually found to be noisy and its propagation delay is sometimes non-negligible as compared with the packet transmission delay. And because of the necessity of flow control and packet retransmission upon error, the delay and throughput performance cannot satisfy the need of a particular traffic type, i.e., real-time multimedia. This paper presents a scheme suitable for the above condition, called the Burst-oriented Transfer with Time-bounded Retransmission (BTTR). The present scheme uses a large transmission window for sending/receiving a burst of time-sensitive data and, within this window, another smaller observation window is repeatedly used for error status feedback via the backward channel. There is time limitation on each retransmission such that the burst of data can be received in a timely manner, however, with some degradation on the packet loss rate. An analysis is given in terms of the expectations of delay, throughput, and packet drop rate. A comparison with an error-free link protocol will also be given. The result shows that the proposed scheme can meet the delay and throughput requirement under reasonable packet drop rate.