A Reassignment Code Allocation Scheme for Multirate Services on OVSF CDMA Cellular Networks

In downlink of OVSF CDMA system, such as WCDMA, Orthogonal Variable spreading factor (OVSF) codes are used as channelization codes to distinguish different physical channels in order to support variable bit rate services. So the allocation scheme of OVSF codes affects the utilization of downlink bandwidth and the performance of the whole network In this paper, we propose a reassignment code allocation scheme which can increase the utilization of downlink bandwidth and decrease the code fragments on the OVSF code tree. The simulation results show that this scheme can reduce the impact of reassignment process to system efficiently and maintain low call blocking ratio at the same time.