Universal Terrestrial Radio Access (UTRA); Uplink transmit diversity for High Speed Packet Access (HSPA)
The present document is intended to capture RAN1 and RAN4 findings produced in the context of the study item "Uplink Transmit Diversity for HSPA" [2]. The study is focussed on schemes that do not require any newly standardised dynamic feedback signalling between network and UE. The uplink transmit diversity schemes maybe categorized into two types of algorithms:
- transmission from 1 Tx antenna (e.g. switched antenna Tx diversity); or
- simultaneous transmission from 2 Tx antennas (e.g. transmit beamforming).
The scope is understood to be limited to schemes which also do not require any semi-static mode configuration signalling for demodulation. The possibility of semi-static disabling of a transmit diversity scheme is not precluded.
The work under this study item aims at:
- evaluating the potential benefits of the indicated UL Tx diversity techniques;
- investigating the impacts on the UE implementation;
- investigating how to ensure that the UE operating an uplink Tx diversity will not cause any detrimental effects to overall system performance;
- investigating the impacts of Tx diversity on existing BS and UE RF and demodulation performance requirements; and
- analyzing how to derive any additional performance/test requirements that are deemed needed as an outcome of the study, as well as understanding the impacts of any such new requirements.
The performance of closed loop transmit diversity, in which the Node-B controls and dynamically adapts the pre-coding vector that a UE shall apply is described in [124].