In the past few years, a considerable increase in number of users as well as offered traffic per user has been experienced in HSPA networks, both in the downlink and in the uplink. In response to this, several features have been standardized in 3GPP. These include multi-carrier HSPA, downlink and uplink CELL_FACH state enhancements, and introduction of downlink and uplink MIMO. However, much of the focus has been on improving downlink performance and further enhancements are needed for the uplink to handle increasing traffic load as well as new traffic types.

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This study should fulfill the following objective of identifying potential technical solutions for increasing the uplink capacity, coverage and end user performance (e.g. latency, achievable rates, etc.). The improvements should address following scenarios:

• Improvements to uplink user plane cell capacity with high number of users (high priority).
• Improvements to uplink coverage and latency (lower priority).

Currently identified areas include:

1. Enabling high user bitrates in a mixed-traffic scenario by means of, e.g., a more efficient method of confining high-RoT operation to dedicated secondary carriers.
2. Rate Adaptation to support improved power and rate control for high rates.
3. Improvements to handling of dynamic traffic on EUL, e.g. more efficient grant handling, improvements to the handling of scheduled and non-scheduled data and control transmissions during bursty traffic, etc.
4. Improvements to EUL coverage when using single RAB as well as various multi-RAB combinations.
5. Improvements to current access control mechanism to provide efficient approach for UTRAN in case of uplink overload.
6. Reduce UL control channel overhead for HSPA operation.
7. Mechanisms to perform UL data compression between the UE and the RAN
   • Evaluate compression gains and performance benefits for different types of smartphone traffic. At least UL capacity, signalling load, UE battery and latency should be considered.
   • Mechanisms to selectively enable/disable data compression when traffic is compressible/uncompressible.
8. Low-complexity uplink load balancing solutions, e.g. a fast uplink carrier switching in Cell_DCH state, especially for configurations where the downlink is configured in multicarrier operation while the uplink is in single carrier.