Ant-colony-based multiuser detection for MC DS-CDMA systems

In this contribution we present a novel ant colony optimization (ACO) based multi user detector (MUD) designed for synchronous multi carrier direct sequence code division multiple access (MC DS CDMA) systems. The operation of the ACO based MUD is based on the behaviour of the ant colony in nature. The ACO based MUD aims for achieving the same bit error rate (BER) performance as the optimum maximum likelihood (ML) MUD, without carrying out an exhaustive search of the entire MC DS CDMA search space constituted by all possible combinations of the received multi user vectors. We will demonstrate that the system is capable of supporting almost as many users as the number of chips in the spreading sequence, while searching only a small fraction of the entire ML search space. It will also be demonstrated that the number of floating point operations per second is a factor of 10, lower for the proposed ACO based MUD than that of the ML MUD, when supporting K = 32 users in a MC DS CDMA system employing 31 chip Gold codes as the T domain spreading sequence.