Enhanced Uplink Packet Access in WCDMA

In this project we have focused on the most promising technologies for the enhancement of Release 99 WCDMA uplink packet access. This includes fast Node B packet scheduling, fast physical layer (L1) hybrid ARQ (HARQ) retransmission schemes, 4-branch antenna diversity, and interference cancellation. Node B packet scheduling allows a tighter control of the interference power received at the base station receiver: Moreover, radio resources can be redistributed among the users more rapidly based on near instantaneous knowledge of their actual requirements. A new scheduling algorithm that performs resource management based on the utilisation of the allocated radio resources is proposed as an alternative to a basic Release 99 packet scheduler implementation. Combined with fast L1 HARQ schemes, the proposed algorithm can provide a cell throughput gain in a macro-cell environment of approximately 25% and 60% for low and high user mobility, respectively. Having moved the packet scheduler functionality to the Node B, it is also possible to introduce a new scheduling concept based on time division multiplexing so that users can be scheduled for transmission with high instantaneous data rates, and potentially when they experience favourable channel conditions. For low user mobility, the cell throughput gain of the proposed channel-dependent schedulers over the basic Release 99 scenario is 50% in a macro-cell environment, and 80% in a pedestrian micro-cell environment. Finally, 4-branch antenna diversity and interference cancellation combined with advanced packet scheduling and fast L1 HARQ schemes are shown to give a total cell throughput gain over Release 99 uplink packet access with 2-branch antenna diversity and conventional matched filter receiver of approximately 250%.