TABLE OF CONTENTS Enhanced Uplink, also known as High-Speed Uplink Packet Access(HSUPA), has been introduced in WCDMA Release 6. It provides improvements in WCDMA uplink capabilities and performance in terms of higher data rates, reduced latency, and improved system capacity, and is therefore a natural complement to HSDPA. Together, the two are commonly referred to as High-Speed Packet Access (HSPA). The specifications of Enhanced Uplink can be found in [101] and the references therein.
At the core of Enhanced Uplink are two basic technologies used also for HSDPA - fast scheduling and fast hybrid ARQ with soft combining. For similar reasons as for HSDPA, Enhanced Uplink also introduces a short 2 ms uplink TTI. These enhancements are implemented in WCDMA through a new transport channel, the Enhanced Dedicated Channel(E-DCH).
Although the same technologies are used both for HSDPA and Enhanced Uplink, there are fundamental differences between them, which has affected the detailed implementation of the features:
In the downlink, the shared resource is transmission power and the code space, both of which are located in one central node, the NodeB. In the uplink, the shared resource is the amount of allowed uplink interference, which depends on the transmission power of multiple distributed nodes, the UEs.
The scheduler and the transmission buffers are located in the same node in the downlink, while in the uplink the scheduler is located in the NodeB while the data buffers are distributed in the UEs. Hence, the UEs need to signal...
