Dynamic Bandwidth Allocation and Scheduling for OVSF-WCDMA Systems

OVSF (Orthogonal Variable Spreading Factor) codes are used as channelization codes in WCDMA system. OVSF codes are getting popular due to his efficiency and flexibility to allocate variable bite rates for different bandwidth requirement of applications. A core design issue of OVSF code allocation schemes is to utilize the codes efficiently such that more data can be forwarded to subscribers and as soon as possible. In literal, there are different OVSF code-allocation schemes have been proposed and evaluated. In this paper, we proposed an alternate OVSF code allocation scheme for single and dedicate code allocation in WCDMA systems. The code allocation scheme consists of two parts: rate allocation and code assignment. First, we decide the rate for each active connection according to user profiles of the connection and available data in data buffer. Second, we assign OVSF code for each active connection according to the results of the rate allocation in the first stage. We compared our propose scheme with other schemes proposed in recent years. Results showed that our scheme outperforms the others, regarding data throughput and delay.