Abstract

Future 3G CDMA networks are expected to have the ability to accommodate variety of users, each with its own transmission characteristics and quality of service (QoS) requirements to be maintained. Compatible multi-access system should provide the means to control (i.e. admission congestion) the flow of traffic and at the same time maintain the QoS requirements. The essence of this work is to introduce an interaction between the physical layer and higher network layers, thus enabling more practical utilization of multi-user detection and supporting services with different QoS parameters. The traffic sources are classified according to their activities and QoS of parameters into two categories, namely stream and interactive traffic. As congestion arises, the interactive traffic users are granted higher priority than the stream traffic users. In this work, a new hybrid Multicode (MC)-CDMA/TDMA medium access control technique utilizing multi-user detection accompanied with a traffic flow control scheme is proposed and analyzed. Secondly, the End-to-End performance criteria of the proposed MAC such as packet delay, channel utilization, etc. are investigated under new Window Measurement-Based admission/congestion control policy where the status of the buffer at the base station is estimated taking into consideration the physical limitations of the base station (i.e. the number of transmission and reception moderns), call and burst level traffic, channel impairment, etc. Thirdly, the hybrid analysis/simulation routine is repeated to investigate and verify the performance of the above proposed MAC along with several versions of congestion policies. The whole system is studied under wide range of traffic load, and different system parameters. The results show that the QoS requirements have been effectively maintained and the proposed system is amenable to practical implementation.