Analysis and simulation of a CDMA PCS indoor system with distributed antennae

Distributed antennae play an important role in PCS CDMA indoor system based on the wideband cellular standard EIA/TIA/IS-95. The trade-off between captured energy and self interference is crucial for distributed antenna system design. This paper examines the relationships between diversity gain and the number of distributed antenna elements with various numbers of diversity receiver branches. The diversity gain factor is derived based on a wideband tapped delay line multipath fading model. The frame-error-rate (FER) improvement is demonstrated by using a simulation system based on the TIA/EIA/IS-95. A three branch modified maximal-ratio receiver with a search engine can provide nearly the same diversity gain as that of a four branch maximal-ratio receiver for a four element distributed antenna system. Simulations show that the three branch modified diversity receiver provides less than a 1% FER when the number of users per cell in a multiple omni-cell environment is less than 10, and the number of distributed antenna elements is between two and five. The FER is more sensitive to the number of antenna elements, when more users are served in the system. The FER could also be improved by reducing the resolution of the diversity receiver branches to one half of the chip interval