| CDMA(Code Division Multiple Access) mobile communication system is more and more widely applied for its advantages of well anti-jamming, perfect safety and great capacity. The capacity of CDMA is limited by noise level and quality of service. Transmitting power should be assigned reasonably according to the requirement of each user so that the interference will be reduced availably and the capacity and quality of system will be improved. System capacity is increased by advancing the control of transmitting power and data throughput is optimized by improving the average data rate of system in this study.In the paper, the effects of various factors on capacity are disclosed and the mathematical models of voice, data and mixed service are established. Because the rising of transmitting power will increase the probability of forward power overload for the characteristic of mixed service, the formula and solution of forward capacity of the mixed system is deducted in term of power effect. The threshold of data throughput is studied in term of assignment of Walsh code.The simulation model of forward capacity is proposed. The forward capacity of CDMA system is simulated on the Monte-Carlo simulation platform. The simulation is carried out on two different conditions, the first condition is that the forward power threshold is fixed and the other is that the forward power threshold is controlled dynamically. The maximum of forward capacity is shown according to the simulation.Soft handoff power synchronization arithmetic and target FER dynamic setup arithmetic are presented in this study. The simulation results show that soft handoff power synchronization improves the forward link capacity and target FER dynamic setup optimizes the data throughput of system. |
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