Research On Relay Coordinated Transmission With Network Coding

As a new type of wireless communication transmission technology, relay cooperative communication has comprehensive advantages of relay transmission and cooperative diversity. Compared with conventional cellular communications network, the introduction of relay cooperative communication can bring multi-antenna and multi-hop transmission performance gain without additionally increasing the number of transceiver antennas. Through relay coordinated transmission, communication entities of the cooperative communication system can share limited frequency resources or time slots to improve the efficiency of the transmission system and utilization of wireless resources, which is a great help in improving the spectral efficiency of prospective wireless communication.Network coding is a new design paradigm in network communication. Introduced into the single antenna or multi-antenna relay cooperative communication system and allowing the intermediate nodes to combine the received signals from a plurality of links, network coding, especially the analog network coding, not only reduces the amount of data transmitted over the cooperative network, but also brings improvement to the throughput of entire network to a certain extent. Relay cooperative transmission based on network coding can overcome the interference between multiple data streams and achieve greater diversity gain. Besides, security and reliability of information transmission will also be greatly improved.This paper mainly studies the joint optimal power allocation between transmitting nodes and the optimal relay beamforming in relay cooperative transmission system based on analog network coding. Relay cooperative transmission based on cognitive network is a field where cooperative communication technology has been widely used. Therefore, this paper focuses on the joint power allocation between the transmitting nodes in a single cognitive relay and cognitive base station scene, and we further consider the multi-antenna relay beamforming in a more practical parallel transmission network under limited power.Firstly, an important application scene of relay cooperative transmission is studied, namely the half-duplex relay cooperative transmission in cognitive network. Mathematical derivation about joint power allocation algorithm between cognitive relay and cognitive base station under perfect channel information is given. In many practical scenarios, only statistical channel information can be obtained, so this part further establishes a corresponding power allocation model and gives the explicit solving algorithm from the perspective of outage probability of primary users which need to meet certain constraints.Secondly, aiming at the phenomenon of resource waste and inefficiencies of half-duplex relay transmission, this part mainly studies a coordinated and relay aided transmission scheme in cognitive network using network coding. The scheme involves a relay aided link and a direct link between cognitive base station and cognitive user and interference between links could be eliminated through network coding. Expression of total system capacity and the appropriate joint power allocation algorithm for transmitting nodes under perfect channel information are given via further derivation.Finally, compared with cooperative relay transmission scheme with single antenna, scheme of parallel multi-antenna transmission is studied in this chapter. In terms of weighted system sum rate maximization and worst link SNR maximization, this part respectively studies the optimal relay beamforming problem under respective criterion. Deduced through convex optimization theories, corresponding optimal beamforming algorithms are given and apart from this, a suboptimal low-complexity algorithm based on linear space expanding is proposed, and simulation and conclusions on the above algorithms are also validated.