Analysis of throughput and fairness with downlink scheduling in WCDMA networks

This paper is concerned with the throughput and fairness analysis in a downlink WCDMA network. The channel model is assumed to include path loss, lognormal shadowing and fast Rayleigh fading. The scheduling schemes investigated are (i) the Round Robin scheme, (ii) the maximum carrier-to-interference ratio (C/I) scheme, (iii) the proportional fair scheme, (iv) the maximum instantaneous signal scheme, and (v) the fading-based signal power scheme. By using an approximation of the probability density function of C/I, throughput and fairness expressions are derived, and a performance comparison among the five scheduling schemes is given. The results indicate that throughput and fairness performance of each scheduling scheme depends on mobile users' location. In general, the Round Robin scheme has the worst throughput performance as compared to the other four schemes. The proportional fair scheme and the fading-based signal power scheme can provide relatively better tradeoffs between the throughput and the fairness. The findings presented here are not only of fundamental theoretical value, but are also of practical interest to the designers of third-generation mobile communication systems based on WCDMA technology.