Frequency overlay of GSM and cellular B-CDMA

摘要

The maximum capacity gain of a cellular broad-band direct-sequencencode-division multiple-access (DS-CDMA) overlay on top of a cellularnglobal system for mobile communications (GSM) system is estimated. Usingngeometrical arguments and a standard propagation model, all relevantncontributions to the carrier-to-interference ratios (CIRs) of the GSMnand CDMA systems are numerically evaluated. It is assumed that the basenstations (BSs) of both systems are unilocated and that the power controlnin both systems is perfect. Furthermore, in the CDMA transmitters andnreceivers, ideal notch filtering is assumed around the occupied GSMnfrequencies of the same cell. Adapting standard limits for the CIRs ofn5-7 dB for CDMA and 9-12 dB for GSM, the total system capacity can benincreased considerably over the GSM-only case: the capacity is increasednby a factor of 1.8-2.9 if no macrodiversity is employed and by a factornof 1.9-3.3 if macrodiversity in the CDMA downlink is applied