| Recently, with the improvement of people’s demand for high-rate and high-quality communications, the design of the mobile communication system become more challenging. However, the development of wireless communication technologies is severely limited by the inherent fading characteristics and instability of radio channel as well as the increasingly scarce bandwidth resources and the hard improved power efficiency. Many scholars have been committed to finding methods and techniques to overcome the fading characteristics of the channels and improve the communication system performance. They made some breakthroughs and achievements, which, MIMO technology is one of the most representative and influential discovery. With multiple antennas equipped on the sending and receiving parts and the use of digital signal processing technology, MIMO technologies increase the data rate and improve the quality of received signal without sacrificing the extra bandwidth and the power of transmission. However, most of the terminal equipment cannot be equipped with multiple antennas due to the limitation of factors, such as volume and electrical power in practice, which limits the MIMO technology greatly. To solve the above problems, a new technique which can form a virtual MIMO system by mutual sharing the single antenna installed on the wireless terminals, which is cooperative communication technology.As a new communication mode, cooperative communication technology has received wide attention since it is proposed and it extends the application of MIMO to more scenarios. In this new communication mode, the dispersed terminal nodes in the wireless network are viewed as distributed antennas, by taking advantage of the broadcast nature of wireless channel in the process of collaboration, diversity gain can be obtained in the cooperative communication system. Specifically, cooperative partners compose of a plurality of mobile terminals in the communication network relay information for each other through auxiliary channel independent of the source node to the destination node, that is, each user not only sends their own information, but also the partners’information. Thus, the independent transmission links which are similar to MIMO channels are produced in the cooperative communication system between the source and destination nodes, namely the virtual MIMO. In traditional cooperation communication systems, the spectrum resources are wasted at least fifty percent due to the use of the orthogonal slots in the Half-Duplex wireless systems, and the Full-Duplex technique, which allows the communication node to transmit and receive signals over the same slots simultaneously, avoiding the waste of the spectrum resources fundamentally and doubling the spectral resource utilization and the channel capacity. In addition, how to design appropriate node selection schemes is an effective method to obtain diversity gain for the multi-user/relay systems.In this thesis, problems are analyzed based on different cooperative modes, cooperative protocols and relay selection schemes. Firstly, a multi-source-single relay-single destination model with two-hop full duplex AF relay is designed, and Rayleigh-Rice hybrid channel is considered in this model. The approximate closed form solution expression of outage probability and the diversity order are derived. Then, the outage performance and the diversity order interrupted by the different degrees of outdated and self-interference are analyzed in simulation. Finally, we design a new relay path selection scheme based on the shortest path fast algorithm (SPFA) for the interference-free multi-hop full duplex DF relay system. Compared with the relay path selection scheme based on the Dijkstra algorithm, SPFA has lower time complexity and can greatly reduce the number of selected relay nodes although at the expense of the system transmission rate to some extent, which saves resources consumption and is more in line with the green communication ideas. |
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