Optimizing the number of dedicated pilot symbols for forward link in W-CDMA systems

A wideband code division multiple access (W-CDMA) forward link employing both a common pilot channel (CPICH) and dedicated pilot (DP) symbols in a dedicated channel (DCH) is assumed. We optimize the number of DP symbols respectively for a low symbol rate case and a high symbol rate case in terms of the system capacity by computer simulation. It is assumed that both CPICH and DP symbols are used for channel estimation and signal-to-interference power ratio (SIR) estimation for forward link closed-loop power control by mobile stations (MSs). This paper first describes the SIR measurement method and the channel estimation method using both pilots, then demonstrates that for the 30-ksps case, one DP symbol provides the best performance, and for the 240-ksps case, the near best performance is achieved when the number of DP symbols is around eight. It is also clarified that the performance levels are mainly affected by the received signal power estimation accuracy and the overhead of the DP symbols