Introduction
A wireless ad hoc network consists of a collection of mobile nodes interconnected by multihop wireless paths with wireless transmitters and receivers. Such networks can be spontaneously created and operated in a self-organized manner, because they do not rely upon any preexisting network infrastructure.
The emergence of multimedia applications in communications has generated the need to provide mobile quality-of-service (QoS) support in ad hoc networks, and such applications require a stable path to guarantee QoS requirements. However, the topology of ad hoc networks is highly dynamic due to the unpredictable node mobility. In addition, wireless channel bandwidth is limited. So, QoS provisioning in such networks is complex and challenging.
QoS routing usually involves two tasks: collecting and maintaining up-to-date state information about the network and finding feasible paths for a connection based on its QoS requirements. Many approaches currently exist to perform QoS routing, most of which consist of routing across the Network layer of the OSI model only. Some approaches utilize both the Network and Data link layer but do not consider the cross layer behaviors. This makes quantifying the QoS parameters difficult and leads to considerations of QoS but does not guarantee QoS.
To address this problem, appropriate cross-layer cooperation is required. Adaptive QoS schemes provide QoS information by factoring the impacts of node mobility and lower-layer link parameters into QoS performance.
Read more about this topic: Adaptive Quality Of Service Multi-hop Routing
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