BER Enhancement of M-ary BPSK Multi-Codes CDMA System based on ACO Optimization Algorithm

Wireless communications have achieved wide development in recent years. There is a great need for wireless communication services that reduce the effects of the transmission channel and transmit data with high data rates. There are many services that increase data transmission rate, such as M-ary BPSK Multi-Code CDMA system. The M-ary BPSK CDMA system has been designed and simulated using Walsh-Hadamard spreading code with lengths of 256, 128, 64, and 32 in the AWGN channel. An Ant Colony Optimization (ACO) algorithm is proposed to find the best constellation points for the M-ary BPSK system that improves the bit error rate performance of the system. The results demonstrate that the M-ary BPSK CDMA system based on the ACO algorithm to find the best constellation points outperforms the system that doesn’t depend on the best constellation points. The results proved that the bit error rate performance was improved by relying on the best set of constellation points in which about 2dB was gained, and this means that more users can be accessed at the same bit error rates. Also, the bit error rate performances for M=8 and M=16 are very close because the 16-ary used best constellation points, and three spreading codes were allocated for each user, while for the 8-ary system, two spreading codes were allocated for each user.