Fair channel-adaptive rate scheduling in wireless networks with multirate multimedia services

In this paper, we study the fundamental problem of allocating with efficiency and fairness the available resources in a code-division multiple-access wireless system that supports multirate multimedia services. Our proposed approach adopts the use of dynamically assigned data rates that match the channel capacity in order to improve the system throughput and overcome the problems associated with the location-dependent and time-dependent errors and channel conditions, the variable system capacity and the transmission power limitation. We introduce and describe two new algorithms, namely the channel adaptive rate scheduling (CARS) and fair channel adaptive rate scheduling (FCARS) algorithms. CARS improves the system throughput by adjusting the transmission rates according to the varying channel conditions and performs an iterative procedure to determine the power index that a user can accept by its current channel condition and transmission power. Based on the assignment of CARS, FCARS achieves the objective of fairness by further compensating the lagging users, while still maintaining all the constraints imposed by the system. The performance evaluation process confirms that our approach achieves, simultaneously, the design objectives of both high throughput and fairness and demonstrate the corresponding improvements.