A cross-layer design for ad hoc wireless networks with smart antennas and QoS support

There are numerous mechanisms to guarantee the quality of service (QoS) of a wireless transmission. In many cases, the application layer sends hard-QoS requirements to the lower layers without negotiation. These requirements, which are defined by specific numeric values, are usually not fulfilled because of mobility or the delay between the signalling and data send procedures. Therefore, in wireless ad hoc networks, it is necessary to define a new conceptual model that changes the traditional vision of QoS integration. A new architecture is proposed; it is based on integration of the cross-layer concept and priority queueing. In this architecture, one node is aware of the state of other components of the network. The information shared between nodes includes the medium access control (MAC) layer metrics (MLM) and the network layer metrics (NLM). The NLMs contain the network topology, path gains and transmission power, while the MLMs contain the MAC layer buffer state. The case examined is a mobile wireless ad hoc network utilising smart antennas and spatial reuse TDMA. With this methodology, scheduling is improved and different QoS services are offered by using the information obtained by the cross-layer structure. Simulation results are presented for an STDMA network, with and without the new structure, and its feasibility is analysed.