The Study of Selection Mechanisms for Mobile Users in WLAN/UMTS Dual Mode Networks

• Main Authors: Yan-Cheng Chang, 張晏誠
• Other Authors: Jiann-Liang Chen
• Format: Others
• Language: en_US
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/28458859310605208411

碩士 === 國立東華大學 === 資訊工程學系 === 92 === The wireless communication technology is a very hot theme for discussion. It provides humankind convenience and infinite. However, there are many different technologies in wireless communication, and every wireless communication system is not the same in functions. By this reason, we talk about the inter-working between two heterogeneous networks in wireless LAN and 3G cellular system. We choose IEEE 802.11 and UMTS as the wireless LAN and 3G system respectively. The advantages of IEEE 802.11 are low cost and high bandwidth. In the other aspect, the characteristics of 3G are larger covered area of its cell and high mobility. If mobile stations are dual mode, they can choose the better network between WLAN and UMTS as their access network to connect other IP networks or communicate with other mobile devices in different situations. By the simulation result, the presentation in delay of integrated WLAN and UMTS system is between 0.0809 second in UMTS and 0.0124 (Streaming service) second in WLAN (Conversational service). On the other hand, the presentation in jitter of integrated WLAN and UMTS system is greater than the jitter in pure WLAN (0.00061) and pure UMTS (0.0049). However, the presentation in jitter has only great effect on communication when mobile users always make handoff between two different networks. Although the analyses of delay and jitter in integrated WLAN and UMTS network are not all better than in pure WLAN and in pure UMTS, integrated WLAN and UMTS combine simultaneously the advantages of UMTS and WLAN in mobility, bandwidth and etc. Necessarily, there is one decision mechanisms to tell mobile stations how to choose the suitable network to access and what time to handoff to the other one. In order to solve the problem, there is one decision algorithm and one decision function to be provided in the essay. It evaluates the cost that the mobile users should pay and the effect of network performance in different network technologies at different moment by the decision function. Relying on the value of the function, the mobile device can choose the proper access network or decide whether to make handoff to other kind of network or not. Besides, different classes of QoS are claimed for different kinds of application services. There is not a static mapping rule between these QoS classes in IEEE 802.11 and UMTS. We will take one applicable mapping table to apply to the inter-working system. The mechanism provided can balance and optimize the performance of the networks by the handoff of mobile users when the performance of some network is down. It also reduces the cost of mobile users effectively. Lastly, it combines the advantages of the heterogeneous networks. The performance of network and the cost of mobile users are also investigated. These results may be valued reference materials in the process of combination of heterogeneous networks.