On Three Issues in Wireless Networking

In this thesis, three issues in wireless and mobile networks are considered. The first issue is the enabling of real-time traffic in wireless local area networks (WLANs). Real-time services such as streaming voice and video require a certain quality of service (QoS) such as low packet loss and low delay to perform well. Four different mechanisms for providing service differentiation in a wireless LAN are evaluated through simulations. Some recommendations are made on which mechanism to use in different scenarios. The second issue concerns ad hoc networking. In ad hoc networks, there is no fixed infrastructure, but all nodes are considered equal and take equal part in the routing and forwarding of packets. This may not always be desirable, as some nodes may be equipped with virtually unlimited power supplies, while others have to rely on battery power. Thus, we propose the creation of “infrastructured” ad hoc networks by the deployment of pseudo base-stations (PBSs), which are nodes that have constant power supply (e.g., through a power outlet or a car battery), do not move, and are present just to act as routers and forward packets for other nodes, thus allowing the mobile nodes to save power. ISAIAH, a routing protocol that enables this kind of network is presented and evaluated against AODV using simulations. It is shown that the use of ISAIAH can reduce the power consumption of nodes while keeping performance at a level comparable to AODV. The final issue is that of routing and forwarding in intermittently connected networks, where there may rarely or never exist a fully connected path between source and destination. This invalidates some of the basic assumptions of traditional networking and renders traditional networking protocols unusable end-to-end. Therefore, routing in such intermittently connected networks is studied, and a novel routing protocol taking advantage of the mobility of nodes, and the predictability of that mobility is presented.