The Research On Capacity Of Inhomogeneous Ad Hoc Networks And Relevant Performance

Wireless Ad Hoc network is special for its no-centre, self-organization, multihop routing and dynamic topology, which make it widely used in areas such as military communication and disaster assistance. And currently most wireless devices that applied in our daily life can support the Ad Hoc mode. Theoretical research about Ad Hoc network has become an important branch of wireless communication in academic field. As a sub-issue of the information theory, the capacity of Ad Hoc network has attracted much attention in the recent decade. This thesis explores the capacity of Ad Hoc network based on some practices of the real network. The research analyzes the performances such as node distribution, network connectivity, transmission model, properties of capacity, transmission consumption and delay especially in inhomogeneous network, which is more close to the real environment.This thesis introduces the Shot Noise Cox Process to model the node distribution and analyzes the cluster-sparse network model which is highly inhomogeneous and discusses differences of node density in various areas in particular. Then the thesis firstly presents a percolation model under the inhomogeneous node distribution based on cluster of nodes and demonstrates that there exist system highways in two directions. The backbone formed by the system highways is the key to analyze the network transmission model. Then the relevant "information pipes" is established between clusters to complete the intra-cluster transmission model up to the transmission model of the whole network. The following content sets the transmission power and puts forward corresponding transmission routing scheme in line with the analysis of the sufficient and necessary condition for connectivity. To approach the lower bound of the capacity in inhomogeneous Ad Hoc network, this thesis analyzes and proves the throughput that nodes can achieve. By comparison, the lower bound obtained in this thesis is tighter than the previous research.Besides, to obtain the minimum energy consumption for a random pair of source nodes to transmit unit message, the thesis studies the minimum transmission energy of the network especially. By approaching both the upper and lower bound, a tessellation model is set up when getting the lower bound to seek empty path that has no node w.h.p. to be the transmission gap. Let the energy consumption during one transmission be the lower bound and calculate the energy consumption in the routing process using the inhomogeneous percolation model when obtaining the upper bound. The thesis finds that there exists a gap between the upper and lower bound through analysis and proof. This is due to that the percolation model can’t cover the whole inhomogeneous network under the constraint of node distribution.Finally, to solve the bound of transmission delay, this thesis takes stochastic network calculus as a tool for theoretical research and the system highway as the main analysis object. It calculates and studies the scaling law of transmission delay using the concatenation property of network calculus. The results show that the end-to-end transmission delay increases nonlinearly with the increase of network size and number of nodes. This relationship can guide the tradeoff between throughput and delay.This thesis focuses on the capacity and analyzes the performance such as energy consumption and transmission delay. The research method is based on the information theory and probability theory. It first demonstrates the theorems and then does some analysis to relevant conclusion. In view of the theoretical results, specific results have been given and practical meaning has been analyzed aiming at giving a guidance to practice.