Author(s) : Nicola Cranley & Liam Murphy Publisher : IGI Global Date       : 2008 Pages     : 544 Format    : PDF ISBN      : 1599048205

The next-generation wireless networks are targeted at supporting various applications such as voice, data, and multimedia over packet-switched networks. Providing quality of service (QoS) guarantees for these applications is an important objective in the design of the next generation wireless networks. However, as opposed to wired networks wireless networks are characterized by substantial packet loss due to the imperfection of the radio medium. This increased packet loss disturbs the successful operation of TCP’s lossbased congestion control mechanism. Therefore standard TCP has some performance drawbacks in wireless links. Moreover, the quality of wireless multimedia applications comprising audio, video and data, is more sensitive to packet delay and delay jitter rather than packet loss. This is due to the fact that interruption in playback due to packet delay is more annoying for the users than degradation of picture quality due to packet loss. Hence, most of multimedia applications use UDP in transport layer due to un-reliable, connectionless nature of UDP. UDP incurs no retransmission delay and jitter. However, UDP itself provides no flow control mechanism so that sources cannot adapt its transmission rate to time-varying available bandwidth depending on the network load. Therefore, it is necessary to have an application-layer flow control scheme, which resulted in protocols such as the RTP/RTCP protocol.

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