Efficient algorithm of OVSF codes allocation for W-CDMA

The problems of low fairness and high blocking probability bottleneck the already algorithms, such as Crowded -first, RDA, DCA and NRA algorithm, etc. This paper presents the HA (Hybrid Allocation) algorithm focused on OVSF single-code allocation for WCDMA system. Initial partition of code tree and OVSF code allocation are two steps in HA. Simulation results show that HA algorithm overcome low fairness and high blocking probability compared to Crowded -first algorithm and RDA algorithm. Simulation results also show significant reduction in average blocking probability and excellent fairness for all kinds of service. Nonrearrangement decreases complexity and can be applied in real-time system by using HA. Sharing area can solve the problem of traffic load variation in different service. Optimal blocking probability is achieved by setting best proportion of sharing area's capacity, i.e., 30%-40% of the whole system.