SIR estimation for closed loop power control with space time transmit diversity in WCDMA FDD downlink

SIR estimation for fast closed loop power control (CLPC) of a WCDMA FDD downlink with space time transmit diversity (STTD) is analysed. It is shown that without STTD encoding/decoding of the DPCCH (dedicated physical control channel) pilot symbols of the two antennas, the SIR estimation suffers from inter-antenna interference. Without modifying the DPCCH pilot patterns in the current 3GPP standard, near-best performance is achieved by using all the pilot symbols for signal power estimation, but only the STTD decoded shaded symbols for interference estimation, to avoid the inter-antenna interference.