Comparison of code reservation schemes at the forward link in WCDMA

We examine resource reservation schemes for the management of orthogonal variable spreading factor (OVSF) codes at the forward link of 3G mobile communications systems employing WCDMA. Like in every multiservice network, different rate calls in 3G systems will perceive dissimilar system performance if no measures are taken and the channelization code tree is treated as a common pool of resources. The paper introduces complete sharing, complete partitioning and hybrid partitioning strategies to manage the code tree, and studies the performance in terms of blocking probability per traffic rate class and utilization of codes. It turns out that fair access to codes by different rate calls and code utilization are conflicting goals, and that hybrid schemes can provide a compromise between these two extremes.