Abstract
Coexisting analog frequency modulation (FM) based on frequency division multiple access (FDMA) and narrow-band code division multiple access (N-CDMA) in adjacent spectrum is studied in this paper. The allocation on different spectrum can avoid the serious performance degradation as transitioning from fully loaded analog FM/FDMA to N-CDMA. The guard-band needed between the adjacent spectrum to maintain acceptable performance degradation is derived and evaluated. Numerical results indicate that at least 255 kHz bandwidth to separate the two systems is necessary. The worst case of the interference from FDMA degrades the performance of N-CDMA, even under appropriate guard-band separation. This study demonstrates the capacity reduction of N-CDMA as coexisting analog FM/FDMA in adjacent spectrum.