Impact of the variation in the background noise floor on UMTS system capacity

Background noise power density is a determinant for the uplink system capacity in a UMTS FDD system. This paper investigates the impact of the variation in the background noise floor on the UMTS FDD system capacity, which is defined as the 6 dB multi-access noise rise over the background noise floor. Measurements of the background noise floor seen at the BS antenna have been performed in the UMTS FDD uplink band in various locations. Typical urban, suburban and rural environments have been evaluated. System simulations demonstrate that the system capacity and the coverage range do depend on the background noise power and hence on the environment where the base station antenna is located. Variations in the maximum system capacity and coverage range of up to 15% can be observed. The results also show that this impact is a function of the service-mix in the network.