Combining Transport Layer and Link Layer Mechanisms for Transparent QoS Support of IP based Applications

Providing IP services with QoS support in heterogeneous networks involving wired and wireless sec tions has been identi ed as a challenging task The goal of this paper is to show how link level mechanisms can be enhanced by transport layer information in order to meet transport layer reliability and delay requirements within wireless scenarios Error control mechanisms in Layer Layer and a combination of them are compared The bene t for TCP based and RTP UDP based applications of using a CDMA based MAC protocol that employs Simultaneous MAC Packet Transmission SMPT are demonstrated It is investigated how the capability of SMPT to use one or several wire less channels can be exploited to stabilize jitter and reduce losses caused by wireless error control Schemes are presented that allow to control the number of channels used by SMPT depending on Layer timing information