Studying And Implementation Of WCDMA Radio Resource Management Algorithm For 3GPP Rel.4

Power is the key question to the radio resource management (RRM) in WCDMA system. The only way to effectively use radio resources is to strictly control the power. While WCDMA system has self-interference characteristics, the power use in it has two-side effects. Increasing the user's station transmition power will improve the user station's QOS, at the same time it will also increase the interference to other users and make their receive quality degradation. The aim of the radio resource management is to manage the power based on user station's QOS (Quality of service). The purpose of studying RRM is to serve more users with limited radio resources (maximum capacity) while still meeting the requirements of coverage and QOS (optimum coverage and quality). Without good RRM technology, no advantage can be seen with best radio transmission technology, or even cause system out of service. RRM algorithm involves a series of topics related to radio resource allocation, e.g. access control, channel allocation, power control, handover, load control and packet resource scheduling, etc.The paper is based on the practice of WCDMA implementation and testing in the lab and field. It includes the theory description of main radio resource algorithms and the detailed analysis of implementation methods for different algorithms. It also gives the examples and analyses for algorithms with real field-test signaling logs. Ten different radio resource algorithms are involved in the paper and can be typed as connection-oriented or cell-oriented. The connection-oriented RRM algorithms are cell reselection, dynamic channel allocation, hard-handover control, blind-handover control, direct-retry, etc. The cell-oriented RRM algorithms are cell-bar control, potential user control, admission control and load balancing control, etc. The paper uses the real signaling logs to analyze the algorithm of RRM, and gives the parameters configuration examples. It is to make clear how the system can know the current radio resource status with measurement reports, how the system can determine the radio status with the radio resource and connection information provided in the measurement reports, and how the system can give out the control command (e.g. handover decision, handover parameter modification, channel reconfiguration, target SIR setting and access parameter optimization, etc).Finally, the innovation of the paper is to take a commercial network environment for algorithm analyzing and optimization verification. Urban coverage area is focused and various optimization methods are used, which combined with different RRM algorithms. The load and power are effectively controlled and balanced. Therefore, the system performance is improved without increasing the cost of network. This further gives the evidence of the importance of the radio resource management algorithms.