Interference Suppression in UTRA FDD Downlink Handover Regions

It is known that significant multi-access interference is generated in a handover region in UTRA FDD downlink, particularly when both the Node-Bs involved in a handover are fully loaded. This paper investigates the use of blind minimum output energy (MOE) adaptive detector for suppressing this multi-access interference. A simple solution to the mismatch problem of the MOE detector is also proposed in the form of closed loop power control (CLPC). It is shown that a significant gain of 1.5 - 2.5 dB in average transmit power can be achieved by the use of adaptive interference mitigating detectors over the conventional Rake receiver. A requirement for the use of adaptive minimum mean square error (MMSE) detectors is the use of short scrambling sequences, which is not supported by current 3GPP specifications for the downlink but the impressive gains achieved by these adaptive detectors make a strong case for the incorporation of short scrambling sequences in the downlink for future UTRA evolution.