The Cross-Layer Design For Ad Hoc Network

In recent years, with increasing demand for mobile services in different scenarios, distributed and self-organized Ad Hoc networks have been rapidly developed and play a more and more important role in social life. However, some mature technology in wired network cannot be directly applied to the Ad Hoc network. How to make the wired network methods adapt to the Ad Hoc network has become a hot research topic.The Ad Hoc network is inherently multidimensional, lack of global information, uncertain and mobile. How to guarantee QoS performance for Ad Hoc network, and design reasonable and effective resource allocation scheme is very challenging. These become some main problems in Ad Hoc network. The traditional Ad Hoc network using the layering design, which is of low complexity, but the layers are separated and information cannot be shared. As a result, the network performance is poor, and the resource utilization is not high. Cross-layer design uses the relevant information between layers, and the network is optimized and designed as a whole, which is suitable to improve the performance of Ad Hoc network. Therefore, based on cross-layer optimization ideas, this paper performs the following researches for Ad Hoc network.(1)A cross-layer triggering mechanism for packet loss to improve the performance of Ad Hoc network.The traditional TCP protocol is designed for fixed hosts and wired network, and it's assumed that any packet loss is due to network congestion. If the standard TCP is directly applied to the Ad Hoc network, it may falsely start the congestion control, leading to performance degradation. A cross-layer method combining the MAC layer, network layer and transport layer is proposed to distinguish different packet losses in Ad Hoc network, and the packet loss may attribute to link congestion, route failure and signal interference. When packet loss occurs, data loss control mechanism is trigged, and according to the current channel condition, the link may respond differently. Simulation results demonstrate the efficiency of our scheme in terms of throughput, delivery ratio and delay in Ad Hoc network.(2) A distributed Newton method for Joint rate and power control.Network utility maximization model is often used for resource allocation in traditional wireless network, based on the lagrangian dual decomposition and gradient distributed algorithm. However, the convergence is slow, and it is sensitive to the step size selection. In this paper, using the information from network layer, data link layer and physical layer, we propose a distributed Newton method to solve the joint rate and power control resource allocation problem in Ad Hoc network. The main idea of the algorithm is to use the current local information to solve the primary and dual variables in each iteration, leading to faster convergence speed. Joint rate and power control can guarantee network utility maximization, and at the same time, reduce the node transmit power, thus effectively prolong the network lifetime.