Design And Realization Of The CDMA Communication System Based On Software Radio Platform

Software-defined radio proposed a good thinking of new designing,manufacturing and using of the idea of wireless communications systems andequipment. It is to get rid of the idea of a totally dependent on the hardware for usingby a general-purpose hardware to liberate the system from the fixedcircuit,meanwhile,increasing the communication system to a new height in using ofsoftware programmable, scalable advantage.As a major technology for3Gsystems,CDMA system is affected by multiple access interference. Multi-userdetection is a method of effectively reducing or eliminating the multiple accessinterference,also has become a research focus.First of all, in this paper I build a CDMA communication environmentthe baseon software radio platform, and completed each module of the hardware set. Theseinclude the baseband signal processing, digital signal modulation and demodulation.Meanwhile,this paper designed a demodulation method according to thecharacteristics of the platform, this method is a non-coherent demodulation method,also simple and able to meet the requirements of real-time. Finally, we realized theCDMA communications on the software radio platform, and achieved the desiredresult.Secondly, this paper get a study on the multiuser detection problem.This paperapplied the ant colony algorithm in multi-user detection, introduced the realizationprocess in detail.At the same time the basic ant colony algorithm is easy to fall intothe shortcomings of the local optimal solution. so the paper proposed based on theimproved ant colony algorithm for multi-user detection. The algorithm updatespheromone using the multi-stage tandem with the new strategy. The first is theselective pheromone update, then the introduction of random disturbance factorpheromone to further modify the final threshold used to determine the maximumrange of the pheromone.Finally,this paper get a simulation for this algorithm,alsocompared this algorithm with some tranditional multiuser detection and ant colonyoptimization,this result prove this algorithm effective.