The Study Of Connectivity And Throughput Based On CDMA-Ad Hoc Network

The Ad hoc network based on CDMA is a network combined the mobile communications with the computer network. It has some characteristics, such as, having no control node, network random organization, multi-hop route, topological changes, and so on. Because of the mobile node, the connectivity and the throughput of CDMA-Ad hoc attract many scholars' attentions.The nodes of CDMA-Ad hoc are mobile randomly. The connectivity of wireless Ad hoc networks has a strong relationship with the node mobility, the node transmitting range, the node number. This paper gives the connectivity formula of mobile Ad hoc networks based on the constant velocity model and the connectivity formula of the non-mobile Ad hoc network. The various simulations and analyses are given according to the node speed, the angle of two speed directions, the transmitting range and the change interval of the speed direction. The various conditions of keeping network connectivity are given in this paper. And the connectivity formulas of 2-hop and multi-hop are detruded. Finally, the application example of the connectivity formulas is put forward.When the CDMA-Ad hoc is connected, the throughput is considered. We know CDMA has a lot of advantages, but it brings MAI(Multiple Access Interference)and Near Far Effect to affect the throughput. In this paper, the MAI is restrained by BMUD(blind multiuser detection). On the condition of the reversible received data autocorrelation matrix and the irreversible one in LMS, A multiuser detection method based on time-varying step size LMS algorithm is proposed. The nonlinear relation of the step gene and c =λ_max/λ_min is defined, which is the ratio of the maximal eigenvalue of the received data autocorrelation matrix and the minimum one. By simulation and analyses, the performance of algorithm is very much improved.When the CDMA-Ad hoc based on BMUD is connected, the relative velocity of nodes, the conditional probability of transmission, the length of data packet, the information quantity of per data packet and the throughput of Ad hoc network are presented based on the constant velocity (CV) model. We get the result that the throughput increases with transmission radius decreasing, transmission velocity increasing and transmission time increasing through numerical simulations. Then we improve the definition of Ad hoc network throughput based on information entropy, and give the relation formula of Ad hoc network connectivity and Ad hoc network throughput. The some simulations, compares and analyses are presented, with the mobile Ad hoc network and non-mobile Ad hoc network.