PERFORMANCE ANALYSIS OF DS CDMA WITH NONCOHERENT M-ARY ORTHOGONAL MODULATION IN MULTIPATH-FADING CHANNELS/

In this paper, the performance of a DS/CDMA system using M-ary orthogo nal modulation with noncoherent demodulation is evaluated. The system operates in a multipath fading channel. A RAKE receiver structure with equal gain combining is used for demodulation. An approximation to th e bit error probability is given which depends only on the first- and second-order moments of the multipath energies. The analysis results a re compared with the results from computer simulations. It is seen tha t the approximation is accurate for multipaths energies with realistic coefficient of variation. System performance is also evaluated in ter ms of the capacity, which is defined as the number of users that can b e supported at a given bit error probability. The approximation is use d to evaluate the capacity reductions due to power variations caused b y multipath fading.