Influence of the common-channel power on the system capacity of UMTS FDD systems that use beam switching

In mobile communication systems using CDMA, common channels needed for proper network operation share the same resource as the dedicated channels for data transmission. However, the 3GPP standard does not specify the amount of transmit power for the common channels. So it is up to the network operator to assign appropriate transmit powers to the various common channels. We study the influence of the power assigned to the common channels on the achievable capacity in UMTS FDD systems that use beam switching. For a system with five beams per 120° sector, we show that a change of the common-channel power per beam by only 1 watt can boost capacity by about 70%.