Mobile LAN integrates Ad Hoc MANET and wide area mobile data network to provide mobile group users the communication capability within the group as well as to the Internet. In the network, all mobile nodes help each other to forward data packets, and all the forwarding paths forms the network topology structure. Due to the physical characteristics of wireless media, the communication efficiency is highly dependent on this topology structure as well as the characteristics of applications. Therefore, the objective of topology management for Mobile LAN is to construct a network topology best to each particular application. Because packet forwarding will increase the traffic load of a node, a good network topology structure should balance the traffic load over the entire network to avoid the early congestion happening on the part of network.

In this dissertation, we propose two routing algorithms that take load balance into account, OTLBR and LTLBR. By selecting the traffic path with the lowest load, OTLBR is able to enhance the load balance and thus increase the communication performance as compared to the traditional minimum hop count oriented routing algorithms. On the other hand, LTLBR take the special characteristics of Mobile LAN further into account. Because the inward and outward Internet traffic in Mobile LAN are concentrated toward the mobile gateway, the closer the hop distance of a node to the mobile gateway, the heavier the packet forwarding load induced to a node. Nodes are first arranged into levels by the distance to the mobile gateway. Traffic are balanced within each level. LTLBR chooses to balance the higher levels before lower levels. Thus, the higher level has a higher possibility to be balanced. At the cost of some performance degradation, it can balance the traffic load better to increase the robustness of the network.

Our performance evaluation shows that our algorithms can efficiently decrease 12% to 30% average packet delay time, and can remarkably reduce the longest packet delay time, as compared to the traditional minimum hop count oriented routing algorithm, MHCP.