Resource management issues for UMTS

One of the most important aspects of third generation systems employing W-CDMA is resource management, which should regulate the operation of a network in such a way that ensures the uninterrupted service provision to the existing connections and at the same time accommodates in an optimum way the new connection requests. This article presents issues concerning resource management and call admission control (CAC) for multimedia W-CDMA systems. It discusses the main factors that affect the capacity of such a network based on the generation of multiple access interference (MAI), on the mobile terminal power limitations and on propagation conditions. The aggregation of different services with different characteristics (bit rate, duty cycle, circuit/packet switching) and QoS requirements (BER, delay) are analysed. The CAC scheme presented is based on the maximum transmitted power by the mobile terminal which attempts to mitigate propagation channel impairments and the effect of MAI generated in the same and other cells. Different models are used for each service to take into account the discontinuous transmission of speech, the variable bit rate of video and the self-similar nature of WWW traffic.