Research On Load-Balanced Routing Protocol For Integrated Space-Ground Networks

In front of unexpected large-scale natural disasters and public emergencies, the fixed communication infrastructure damaged can't meet the communication demands of emergency scenarios. It is necessary to design a kind of emergency network integrated with general communication system. Integrated space-ground networks rely on the near space platform system with fast and flexible deployment, which has become the best choice of the construction of emergency communication network. At normal time, near space platform vehicle layout on the remote areas which is difficult to cover by satellite.It can be deployed to the disaster area above the platform in emergency, as a supplement or replace the ground communication system. For near space networks and ground equipment seamless connection, it is necessary to solve network congestion and bottlenecks between space and ground equipment, and it is one of the important technical content to research the high efficient and reliable load-balanced routing protocol.The existing routing protocols are mainly based on single layer ad hoc network, and characteristics of network components are similar. However, link states and node load of integrated space-ground networks are not identical, it is necessary to put forward a new network routing protocol to support integrated space-ground networks. This article will focus on the load-balanced routing protocol of network communication. Two major contributions are made in this thesis:Firstly, the existing metric measurement methods mainly concentrate on wireless Mesh network, they only consider the link state information, without considering the node load information. However, the traffic of each node integrated space-ground networks, it is necessary to consider the node load. On the basis of the structure and characteristics of integrated space-ground networks, combining the characteristics of link and node with the expected transmission delay ETT weight measurement, this article proposes a metric measurement method based on link state and node load. With the help of the metric measurement method network will be flat, it is convenient to design the routing protocol.Secondly, on the basis of existing routing algorithm in ad hoc networks and the characteristics of integrated space-ground networks, the ant colony algorithm is introduced into the OLSR routing strategies. This article proposes a load-balanced routing protocol based on ant colony optimization algorithm, taking the link delay, packet loss rate, bandwidth, link stability, MAC layer cache queuing delay into consideration. Meanwhile, in this article, the ant colony algorithm will link into the pheromone volatilization rate of stability, pheromone volatilization speed adjustment according to the link state. At the same time, in order to adjust pheromone volatilization speed according to link state, link stability is added to calculation of the pheromone evaporation rate.Research results show that the proposed routing protocol is able to apperceive the change of link state and the node load of the network timely, which reduces the rate of packet loss and the end-to-end delay efficiently. Thesis results provide a strong support for the application of integrated space-ground networks load-balanced routing protocol in the future.