A hybrid CDMA multiuser detector with ant colony optimization and code filtering system

In this study, a hybrid approach with Ant Colony Optimization (ACO) and Code Filtering System (CFS) is proposed for DS-CDMA multiuser detection. In CFS, the method of Lagrange multipliers is applied to set the threshold in order to make the judgment of the codes of users. Compared with the ACO multiuser detector, the hybrid detector can both filter out the most part of the wrong codes from the output of the ACO multiuser detector and decrease the iteration numbers in the process of hunting the solution. Via computer simulations, it's shown that the performance of the hybrid detector in reducing bit-error rate and decreasing the computational complexity is much better than that of the ACO multiuser detector and is very close to the performance of the optimum multiuser detector. At the same time, its computational complexity is only 20.7% of the complexity of ACO, which can greatly increase the rate of data processing and enhance the real-time performance of the systems.