3G must offer high data rates since it should support real-time multimedia services; one performance enhancement, the use of the OVSF code tree, has adopted in 3G WCDMA networks. Unfortunately, this technique allows the link capacity to be set at the base rate times powers of two. This results in wasting bandwidth while the required rate is not powers of two of the basic rate. Several multi-code assignment mechanisms have been proposed to reduce the waste rate, but incur some drawbacks, including high complexity of handling multiple codes and increasing cost of using more rake combiners. Our solution is a dynamic grouping code assignment that allows any rate to be achieved with a single code for any possible rate of traffic. The dynamic grouping approach first forms several calls into a group. It then allocates a subtree to the group and dynamically shares the subtree codes based on time-sharing of slots within a group cycle time. The waste rate and code blocking is thus reduced significantly. Since transmission delay and jitter may occur in such a time-sharing approach, two schemes of cycle interleaving are proposed to minimize delay and jitter. Numerical results demonstrate that the proposed approach reduces the waste rate and increases the system utilization obviously, and the proposed cycle interleaving schemes minimizes delay and jitter significantly.

This paper proposes dynamic distributed unicast and multicast routing algorithms for multiple classes of QoS guaranteed networks. Each link in such a network is assumed to be able to provide multiple classes of QoS guarantee by reserving various amounts of resource. A distributed unicast routing algorithm, DCSP (Distributed Constrained Shortest Path), for finding a QoS constrained least cost path between each O-D (Originating-Destination) pair, is proposed first. Two class reduction schemes, the linear and logarithmic policies, are develpoed to prevent exponential growth of the number of end-to-end QoS classes. Based on DCSP, two distributed multicast routing algorithms, DCSPT (Distributed Constrained Shortest Path Tree) and DTM (Distributed Takahashi and Mutsuyama), are proposed to find QoS constrained minimum cost trees. Numerical results indicate that DCSP strongly outperforms previously proposed centralized algorithms and it works better with the linear class reduction method. For the multicast routing algorithms, the DCSPT with linear class reduction method yields the best performance of all multicast routing algorithms.