Research On Access Technology In LAS-CDMA System And It's Simulation

Code Division Multiple Access (CDMA) is the leadingtechnology of the new generation wireless communicationsystem, and LAS-CDMA (Large Area Synchronization CDMA),based on a kind of frequency spread code with (IFW)Interference Free Window, and has cut a figure in this domainfor its many superiorities. Besides, LAS-CDMA is a kind ofnew technology raised in recent years with independenceintellectual property, so it is of great signification for the mobilecommunication technology in our country to work at it.Meanwhile, it is a new challenge. Applying an innovativedesign of frequency spread code which is called LAS code isthe specialty of LAS-CDMA (large area synchronizationCDMA) system. This method of design is to enlarge the systemcapacity by the way of reducing the interference produced bysystem. LAS code is composed of cods of two stages, which arecalled LA code and LS code. LAS-CDMA is intelligentfrequency spread code, operating on system with effectiveinterference free multiple access code, LA code and LS code,it can reduce even eliminate interference produced completely.In this paper, we mainly research on the application ofrandom multiple access wireless communication technology inTD-LAS CDMA system. The paper can be divided into threeparts. The first part is about the research on random multipleaccess technology. The second part is about the research onwireless access technology of the two primary communicationsystem—GSM,CDMA system. The last part is about theresearch on the combination of random multiple accesstechnology and LAS-CDMA system.In the research on random multiple access technology,ALOHA multiple technology is discussed and expoundedmainly. The algorithm of Slotted ALOHA system's stability isalso studied, and it is simulated with MATLAB, in order toacquire the relationship between system's stability and system'srate of throughput. At the end of this part, we analyze the resultof simulation, and table some improved proposal about thealgorithm of Slotted ALOHA system's stability.In the research on the wireless access technology of thetwo primary communication system — GSM , TD-SCDMAsystem,we study the structure of frame and the process ofsystem access in detail.In research on wireless access technology of LAS-CDMAcommunication system, we mainly study on the key principleand frame structure of LAS-CDMA system detailedly. Then,according to the characteristic of frame structure, we work outthree simple models of LAS-CDMA system traffic channel, andsimulate the three models. With MATLAB particularly, provethe feasibility of the models.According to research on the technology of randommultiple access , GSM , TD-SCDMA system wirelesscommunication, we came down with some research conclusionsas follow.Having researched on principle of random multiple accesstechnology especially slotted ALOHA system. Having achievedthe curve of relationship among stability,throughput andretransmit probability.Having researched on principle of GSM,TD-SCDMAsystem wireless communication technology and character offrame structure.Advancing three kinds of subframe occupancies model ofsystem traffic channel according to research on process ofLAS-CDMA system wireless communications and framestructure of system.