OVSF code slots sharing and reduction in call blocking for 3G and beyond WCDMA networks

OVSF (Orthogonal Variable Spreading Factor) codes are used in WCDMA uplink and downlink transmission for multirate traffic. The orthogonal property of these codes leads to code blocking and new call blocking. Two code (or slot) sharing assignment schemes are proposed to reduce the effect of code blocking using OVSF and NOVSF (non blocking OVSF) codes. The schemes favor the real time calls as they are given higher priority in all 3G and beyond networks. The benefit of the proposed scheme is the better handling of non quantized rates compared to other novel single code and multi code assignment schemes. Both single code and multi code options are analyzed for OVSF as well as NOVSF codes. Simulation results are discussed to show the benefits of the proposed scheme. KeyWords: OVSF codes, slots, time sharing, multiplexing, single code assignment, multi code assignment, real time, code blocking.