Downlink performance of a DS-CDMA wireless local loop system

The air interface performance of a direct sequence code division multiple access (DS-CDMA) based wireless local loop (WLL) system concept is investigated. The main objective of the paper is to elaborate the dependence of the system performance on the radio channel impulse responses (CIRs). Due to the fact that the CIRs in WLL systems may significantly differ from mobile radio CIRs, WLL typical CIRs were obtained using a wideband channel sounder. In order to attain an upper bound for the cellular capacity of the considered concept, a downlink multiple access interference (MAI) analysis has been carried out. As a result of the investigations, it turns out that the cellular capacity in a WLL system is not significantly different from that of a mobile radio system. This is due to the fact that the advantage of the more favorable characteristics of the WLL radio channels is compensated by the more stringent demands imposed on the service quality of WLL systems.