SIR estimation on common pilot channel with the knowledge of data to pilot power ratio for closed loop power control in WCDMA FDD downlink

For the closed loop power control (CLPC) of WCDMA FDD downlink, the signal to interference ratio (SIR) is typically estimated by using the dedicated pilot symbols in the dedicated physical control channel (DPCCH). In this paper it is shown that by estimating the SIR on the common pilot channel (CPICH) along with the knowledge of DPCH to CPICH power ratio, the CLPC performs much better as compared to the case when the SIR is estimated on the DPCCH pilot symbols only. It is proposed that additional slot formats be introduced in the 3GPP forward link slot formats with a reduced number of DPCCH pilot symbols and a corresponding increase in the data symbols. These slot formats could be utilized when the CPICH is available and will also result in an increase in the data throughput.