Research On Key Technologies Of Long Distance Wireless Relay Communication Systems

With the rapid development of wireless communication technology, the long distance wireless commu-nication has gotten wide application. Especially for some special areas, such as the areas striked by the earth-quake, floods or other natural disasters, settled network communication facilities may be destroyed. Mobile relay nodes (MRNs) which are mounted on top of cars, planes or other vehicles, can provide reliable access points for passengers far away from the base station. So the cell capacity and the user experience can be im-proved by deploying MRNs in the long distance wireless relay communication system. The key technologies of the long distance wireless relay communication system are studied in this paper.Firstly, basic concepts and research background of the long distance wireless relay communication sys-tem are described in the thesis. The characteristics and different types of wireless communication fading channels are analyzed and the typical scenarios for the mobile relay communication are classified briefly. The basic principles and the advantages and disadvantages of the Data Link are introduced. The Time Divi-sion Multiple Access architecture and key technologies of the Data Link are further discussed.Secondly, the performance analyse of the long distance wireless relay communication system is stud-ied. The direct transmission mode and relay assisted transmission mode are introduced on the basis of the establishment of the long distance wireless relay communication system model. Concepts and details of the system capacity and outage probability of two transmission modes are elaborated, and the system capacity is improved and the outage probability decreases by carrying out the relay assisted transmission mode according to the simulation results.Thirdly, the physical layer link of the long distance wireless relay communication system is designed. Some anti-jamming technologies are proposed and designed among the physical layer link of the long distance wireless relay communication system, including Reed Solomon encoding, the cyclic code shift keying soft spread spectrum, interleaving and minimumshift keying. The bit error rate (BER) performance is improved significantly by adopting the design scheme of the physical layer link that is proved by the simulation results.Finally, the channel estimation technology in the backhaul link under the high speed mobile communica-tion environment is studied. The baseband model of the mobile communication system is introduced and the classic channel estimation methods are summarized in terms of the pilot pattern design. The new Rayleigh fading channel simulation model is used for the simulation and comparison of the classic channel estima-tion methods. Furthermore, the basis expansion model for fast time-varying channel is studied, and the pilot insertion mode adopted to estimate basis coefficients is improved. The channel estimation accuracy is effec-tively increased by utilizing the distributed pilot insertion mode compared with that utilizing the traditional centralized pilot insertion mode according to the simulation results.