Performance Analysis Of Vertical Handover For Heterogenous Wireless Network

With the appearance and development of various wireless access technologies, the users increasingly demand the global mobility and service continuity, so the trend for the wireless network is to combine different access networks into a single one. To guarantee the seamless roam capability of heterogeneous network, the vertical handover mechanism has been used widely.WCDMA has been used widely as a mature 3G technology, and many experts has done a lot of research in the vertical handover between WLAN and WCDMA. Nowadays, a new 3G technology, TD-SCDMA, proposed by China appears. This new technology has drawn the attention all over the world and becomes the focus of most research.This thesis researches mainly in the mechanism of vertical handover between WLAN and TD-SCDMA, which is compared with the handover between WLAN and WCDMA. There are many criteria used to estimate the performance of handover: jitter, delay, capacity, call-dropping probability and call-blocking probability. In this thesis, only the call-dropping probability and call-blocking probability are taken into account to present the seamless roaming capability between different networks in the two systems, and the simulation is done through the platform of MATLAB.Firstly, this thesis introduces the technology background of WCDMA, TD-SCDMA and WLAN, and it decribes the characteristics of MATLAB too. Then the admission control mechanisms of the three networks will be introduced in detail, and this mechanism is used to check that whether there is enough network resource to satisfy the new user's requirement. Then the call-dropping probability and call-blocking probability of heterogeneous networks can be worked out.This thesis brings some typical kinds of traffic into the heterogenous network to analyze the performance of vertical handover. Because of the complexity of the realistic network, this thesis simplizes the simulation scenario: The simulation area is a square of 1000m* 1000m within a cell of 3G network; there are two WLANs existing in the simulation area; the WLAN's covering area is a circle with the radius of 100 meters; the users in the heterogeneous networks are all supposed to be pedestrians.Through the study of former simulation of wireless network, this report also introduces the essential sub-models with their implementation. These sub-models include handover model, traffic model and mobility model. The handover model is used to decide when the handover should be initialized; the traffic model is used to simulate the related traffic behavior in the network; mobility model is used to simulate the mobility characteristics of every node in the network.Based on the sub-models mentioned before, this thesis simulates the two vertical handovers of WCDMA/WLAN and TD-SCDMA/WLAN repectively which are compared with each other here too.In the end, this thesis sums up all of the content and describes the deficiency of the research as well as the future work.