Efficient Scheduling for the Downlink of CDMA Cellular Networks using Base Station Selection Diversity

Efficient packet scheduling in CDMA cellular networks is a challenging problem due to the time variant and stochastic nature of the channel fading process. Selection diversity is one of the most effective techniques utilizing random and independent variations of diverse channels to improve the performance of communication over fading channels. Exploiting base station selection diversity, in this paper, we propose two scheduling schemes for the downlink of CDMA cellular networks. The proposed schemes rely on the limited instantaneous Channel State Information to transmit to the best user from the best serving base station in each time slot. This technique increases the system throughput by increasing multiuser diversity gain and reducing the effective interference among adjacent base stations. Results of Monte Carlo simulations are given to demonstrate the improvement of system throughput using the proposed scheduling schemes. We also investigate the issue of fairness analysis of wireless scheduling schemes. Due to the unique characteristics of wireless scheduling schemes, the existing fairness indexes fail to provide a proper comparison among different scheduling schemes. We propose a new fairness index to compare the overall satisfaction of the network users among different wireless scheduling schemes. This approach complies with the definition of max-min fairness which is a widely accepted notion of fairness for data communication networks.