Research On Distributed Differential Transmission Scheme Based On Cyclic Delay Diversity For Two-way Wireless Cooperative Relay Networks

Wireless cooperative communication network utilizes multiple communication nodes distributed in different geographic locations to form a "virtual" multiple-input multiple-output (MIMO:Multiple Input Multiple Output) systems, to better tap the space between the antenna diversity, thus achieving high reliability information transmission, mobile terminal volume to overcome the traditional MIMO system in actual application process being and power constraints, caused widespread concern in recent years, scientists at home and abroad. Among them, the wireless communication method of differential transmission cooperative based on the idea to avoid complex communication nodes channel estimation overhead, saving bandwidth resources worthy of further exploration. In this thesis, the existing differential cooperative relay transmission method most common way of encoding transponder complexity, versatility poor detection of high complexity and other outstanding issues, expand the research work, the specific contents are as follows.(1) In the study of existing cooperative relaying key technologies, based on the analysis focused on linear constellation precoding (LCP:Linear Constellation Precoding) technology to obtain multi-antenna wireless communication systems spatial diversity to improve the inherent reliability of data transmission mechanism and implementations, the technology detects the corresponding reception side tends to increase with increasing complexity of the number of relay nodes increases exponentially difficult to meet the requirements of real-time communication.(2) In order to reduce the design process collaborative communication system and receiver detection complexity, exploring the cyclic delay diversity (CDD:Cyclic Delay Diversity) technology combined with point and distributed cooperative communication systems, identified in a number of relay nodes CDD data forwarding technique used during specific implementation.(3) In the study of existing differential cooperative relay transmission method, based on the combined strengths of both technologies CDD and LCP is designed to complete a frequency of one in three time slots differential space-time coding transmission of two-way communication scheme. In this embodiment, two communication slots each source node designed the first two differential coded data broadcast to all relay nodes, wherein the message comprising a matrix using the normalized constant modulus modulation symbol or design in the third time slot after each received signal from the relay node to a different time slot to multiply the cyclic delay forwarded to both the source node, the source node is detected based on the corresponding original encoded data and forwarding criteria.This thesis proposes a differential transmission scheme due to the encoding process messages used in the LCP matrix technology, which can achieve high spatial diversity gain, improve the reliability of the transmission system; due at the relay node uses a cyclic delay forwarding can simplify the design process of differential transmission, reducing the complexity of detecting the receiving end of building the future of distributed wireless networks, has some significance and application value.