In this paper, the performance of a coherence multiplexed (CM) turbo-coded optical PPM CDMA network is evaluated in terms of bit-error-rate (BER), number of users (K) and for various interleaver lengths (N) taking into account the effects of the thermal noise and shot noise of APD detectors. For a fixed K (=10), the BER of a CM system is reduced by an order of 10-5 than that of the single-ended direct detection system. For a typical data rate of 1Gb/s, and a specified BER of 10-6, it is found that the number of simultaneous users increases to 50. Turbo decoding is done using Log-MAP algorithm with different interleaver lengths of N = 10, 50, 100 resulting in the reduction of BER to 10-9, 10-10 and 10-11 respectively and by applying performance bounds on the turbo-coded system, the maximum number of iterations to reach a BER of 10-14 are limited to four in this system.