Research On The Joint Design Of Transmission And Reception In Relay Cooperative System

The efficient and reliable transmission in wireless communication system has always been the major target in mobile communication industry. In wireless communication transmission, due to the fading effect, the communication coverage is largely compromised. As an efficient solution to that problem, relay technique has attracted more and more attention. As a simple transmission node, the relay station can act as the bridge between source node and destination node. It can effectively combat channel fading, extend the communication coverage, improve the cell edge throughput, and enhance group mobile services etc.In the future mobile communication system, high system throughput, high data rate and high spectrum efficiency have been treated as the potential requirement. Hence, the cooperative strategy for balancing system overhead and the system performance has received wide attention and thorough analysis. The cooperative techniques can also be applied into interference cancellation, multi-point scheduling, joint processing and other aspects of the application in the relevant protocol standards such as LTE/LTE-A.Based on cooperative relay systems, this paper is designed to analyze the advanced technology on the joint design of transmission and reception. Firstly, the background theory of the paper is introduced. The background includes the current relay system and cooperative strategy of existing technology, and the current system based on communication effectiveness and reliability principle, which can improve the current system. Then the paper discusses relevant contents both from the theoretical aspect and real implementation aspect. On the basis of cooperative relay system, the main research work consists of three parts:communication protocol design, balanced utilization of reliability and efficiency, the improvement on implementation value.In theoretical research, this paper first studies the transmission time slots allocation for the source node and the relay node. Given analysis on transmitting and receiving phases, this paper is aimed at discussing the strategy which can improve the transmission efficiency, and constructing the corresponding communication protocol, which can guarantee the improvement on system performance even without the interference cancellation process. In traditional three-node relay system, the source node is in idle state during the second slot when relay forwards the packet. To improve the exploitation on resource, this paper designs the protocol that can use the source node on the second transmission slot efficiently so that both the source node and relay node can transmit simultaneously. Besides, this paper strictly proves that even in the absence of the interference cancellation technique, the relay cooperative system can achieve second order diversity gain and capacity gain.Moreover, according to the mentioned basic idea and evolution on relay system communication mode, this paper introduces research on transmission reliability and efficiency. By combining the proposed cooperative relay communication protocol with Relay-Assisted Hybrid Automatic Repeat reQuest, the system reliability can be improved. Besides, in the second transmission slot of source node, the principle in network coding is adopted, the retransmission and new data are combined together. Meanwhile, at the receiver end, the decoding process in corresponding virtual MIMO is conducted to increase the transmission efficiency.Last, considering the situation in which the relay needs to serve several users, this paper discusses multi-user MIMO enhancing technology which can adapt different channel conditions, such as precoding. Considering the delay constraints and hardware overhead in real application, the transmitter and receiver do not adopt channel inversion precoding technique which has a strict requirement on real-time. Instead, it utilizes the codebook-based precoding technique as a traditional cooperative method. From the aspect of practical engineering, this paper propose the binary codebook design standards, which can greatly balance the system performance and overhead, besides it can be largely applied to the existing codebook design method. In codebook design process, the element in codebook matrix is transformed into the power of two. In hardware implementation, the complex multiplication of data stream and codebook is calculated by simple shift, which can greatly saves the consumption of hardware resources. However, this operation is bound to bring the change into codebook energy and the property of original codebook. Therefore, the obtained codebook needs to be processed. This paper discusses single user and multi-user scenarios respectively, and then proposes a corresponding codebook generation algorithm.