Hybrid single code and multi code design to reduce complexity in OVSF codes based wireless networks

In WCDMA networks, OVSF codes are limiting factor due to the problem of code blocking. The optimum OVSF code selection becomes essential requirement for all WCDMA networks. The paper proposes two novel designs to reduce the complexity in the traditional OVSF code designs. The first method uses the combination of traditional leftmost code assignment (or crowded first assignment) and dynamic code assignment. This reduces the number of code assignment significantly. The second method uses the combination of leftmost code assignment (or crowded first assignment) and multi code assignment. The limiting factor in multi code scheme is the number of rakes (channels) required for new calls and these are significantly reduced using the proposed hybrid design. Simulation results are given to demonstrate the superiority of the proposed design.