The Research Of The Capacity Of Cognitive Wireless Mesh Networks

Capacity analysis is a basic and necessary work to provide guidance and reference for the system design and deployment of cognitive wireless Mesh network (CWMN). At present, the research of cognitive wireless Mesh network capacity has just commenced, and most of the literatures directly get the throughput capacity of the network by simulation, which lack the derivation process of the closed-form solution and the theoretical analysis of the quantitative results.This paper firstly describes the theoretical basis and the present situation of the cognitive wireless Mesh network capacity research. Based on the proposed model, a quantitative result of the average throughput capacity of CWMN with power control is deduced. And then, an analytical model using a three-dimensional Markov chain is investigated to derive the capacity of cognitive users operating under heterogeneous spectrum environment. The main contents are as follows:In this paper, under the large-scale channel fading model and protocol interference model, a closed-form solution for the maximum channel capacity of each node with power control is firstly presented, under the constraint that the interference tolerated by the primary users does not exceed a threshold. And then, with the deduced channel capacity result, the average throughput capacity of CWMN is derived based on two regular topologies, i.e. square topology and triangle topology. The simulation results indicate that the capacity is effectively improved with power control, and affected by topology, tolerated interference threshold, the number of cognitive users and primary users. Next, the network capacity of cognitive users under heterogeneous spectrum environment is analyzed and deduced. Firstly, we using a three Markov chain model to solve the steady-state equation under heterogeneous spectrum in CWMN, the closed-form solution for blocking and dropping of cognitive users are derived. Based on these results, we derive the closed-form solution of cognitive user network capacity. Due to queuing theory introduced to the network analysis, we make the computational complexity of derivation process greatly simplified. Simulation results verify the result of network capacity under heterogeneous spectrum is higher than that under homogeneous spectrum. As the arrival rate of primary user increases, the network capacity of cognitive users will decrease, while with the increase in the services rate of primary user, the network capacity of cognitive users will also increase.By researching the quantitative network capacity for CWMN Based on power control and heterogeneous spectrum environment, this paper provides theoretical guidance and reference to continue to study the performance and actual deployment of CWMN.