Performance of Adaptive Admission/Congestion Control Policies on a Hybrid MC-CDMA/TDMA Integrated Multimedia Networks

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

Adaptive admission/congestion control policies for CDMA-based wireless internet

Radio resource management (RRM) is vital for the next generation wireless networks. RRM comprises many functionalities and this paper focuses on the investigation of the performance of several adaptive call admission/ congestion control policies based on a window-measurement estimation of the status of the buffer at the base station under the hybrid TDMA/CDMA access scheme. In our study, we interrelate the physical limitations of the base stations (i.e. the number of transmission and reception modems), call and burst level traffic, instantaneous buffer conditions and end-to-end bit error performance in one queuing problem. Subsequently, a windowmeasurement estimator is implemented to estimate the likelihood of buffer congestion at the base station. Accordingly, the traffic loads shall be controlled. We use event-driven simulation to simulate the multimedia integrated CDMA networks where heterogeneous traffic users are multiplexed into a simple TDMA frames. The simulation results show outstanding performance of the proposed call admission/congestion control policies in guaranteeing QoS requirements