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The next generation cellular wireless network is expected to provide a broad range of multimedia services, where the traffic asymmetry between uplink and downlink is significant. The code division multiple access system with time division duplex mode (TDD-CDMA), adopting unbalanced slot allocation between uplink and downlink, is a good solution for this traffic asymmetry. Here a QoS adaptive multimedia service framework is proposed to control the multimedia traffic in TDD-CDMA cellular wireless networks. The scheme operates at the connection-level where the CDMA code of ongoing call can be dynamically changed to provide an acceptable trade off level between connection blocking and dropping probabilities for different traffic class. The proposed scheme is designed to take advantage of the adaptive code allocation algorithm in order to enhance the system utilization, and blocking & dropping probabilities of calls. Although orthogonal variable frequency spreading (OVSF) code is used in simulation here, the paramount interest is on algorithm that allows optimum use of TDD-CDMA resources i.e. code and time slots. Simulation result shows that on the expense of resource allocated to non real-time services, the call dropping and blocking rate for real-time services can be minimized.
Date of Conference: 14-17 Dec. 2008