Performance Analysis and Allocation Strategy for the WCDMA Second Scrambling Code

The WCDMA downlink is limited by Node-B cell power and the number of channelization codes. With upcoming capacity enhancement techniques, like MIMO and HSDPA, the potential limitation in channelization codes becomes visible more frequently. The WCDMA standard allows for allocation of traffic on a secondary scrambling code, which is non-orthogonal to the primary scrambling code. This paper analyzes the capacity impact of using the secondary scrambling code. In addition this paper introduces an allocation strategy for traffic to the secondary scrambling code. The analysis shows a potential gain in secondary scrambling code usage for this strategy.