Several Different Approaches to QoS Routing Protocol

In this paper, we discuss several different approaches to providing QoS at the routing layer, and we provide a comparison of these techniques and a look at some open issues to supporting QoS at the routing layer. QoS guarantees are not possible in MANETs, and soft QoS and QoS adaptation are proposed instead. However, if a network changes too fast to propagate the topology status information, it is impossible to offer even soft QoS. For example, layered coding allows enhanced layers of different quality levels to be transmitted, provided a minimum bandwidth is guaranteed for transmitting the base layer. Therefore, these types of applications can benefit from QoS adaptation. By providing feedback to the application about available resources, the application can alter its coding strategy to provide the best quality for the current resource limitations. Routing is used to set up and maintain paths between nodes to support data trans-mission.. To support QoS, the essential problem is to find a route with sufficient available resources to meet the QoS constraints, and possibly add some additional optimizations such as finding the lowest cost or most stable of the routes that meet the QoS constraints. Given these goals, the following are the basic design considerations for a QoS routing protocol.