Researches On Theories And Performance Of Network Coding Cooperative System

In order to satisfy the demand of multi-rate and multi-service communication, next generation of wireless telecommunication systems need to provide better mechanism and technology to both speed up data transmission and better serve all demands of QoS. Multiple Input Multiple Output (MIMO) technology, as one of key technologies in the next generation of wireless telecommunication, is able to provide reliable broadband data service by utilizing limited frequency spectrum resource. As a virtual technology of MIMO combining advantages from both diversity technique and relay transmission, cooperative communication combines has attracted exclusive attentions in industries. Network coding theory is an important break-though in network communication and development. The gateway nodes in network not only focus on simple store-and-forward, but also encode the information that passes by; therefore, the coding have enlarged the capacity and stability of entire network. This dissertation seeks to apply the method of network coding in cooperative communication system, mainly focusing on research and analysis in system performance and implementation alternatives.The mainly works include: research on the application of linear network coding in cooperative communication system . Analyzed application of linear network coding in both relay cooperative communication system and cooperative communication system. Comparing applications in relay cooperative communication with proposed common distribution antenna system (DAS) and network coding DAS mode, the dissertation dilated communication channel influence's details on system performance between source nodes and relay nodes. Moreover, it proposed a corresponding algorithm on power allocation with theoretical analysis and simulation result. The result demonstrated that the quality of two different approaches is related with transmission performance within cooperative communication channel and multi-clients channel. When cooperative communication channel is in better condition, network coding approach is superior to none network coding systems. On the other hand, if the cooperative channel is in bad condition, none network coding system has advantages over network coding system. However, the difference is not obvious. Hence, combined network coding has advantages in band resources and order of complexity.Proposed one of Space-time network coding cooperative communication system. Space-time coding is an approach that well integrates coding, modulation, sending / receiving, and diversity. It benefited from not only network coding, but also diversity, which has effectively improved transmission performance in wireless fading channel. Collaboration of network coding, space-time coding, and cooperative communication will definitely improve the overall system performance. This dissertation combined these concepts and proposed a method in space-time coding in cooperative communication system and provided computer system simulation. When the cooperative communication channel is in ideal condition between two nodes, and nodes are symmetry in uplink channel, the coding-gain can be improved by 4～5dB comparing with adopting cooperative communication with only space-time coding when Pe=10^-3.Proposed a new cooperative communication system as network convolution coding cooperative communication system .This dissertation referred the principle of network coding together with network encoding, convolution encoding, and cooperative communication, and proposed a new cooperative communication system as network convolution cooperative communication system as well as detail analysis on new system architecture and performance. Confined in upper-bound of error-bit-rate in Rayleigh block fading and fast fading channel system, the computer simulation results indicated at least 3dB system performance improvement in both cooperative coding and none cooperative coding approaches.Proposed a new improved network convolution cooperative communication system. The selection of different convolution codes has great influence in performance of network convolution coding cooperative system. As a conclusion, the dissertation proposed a method to improve deficiencies in network convolutional coding cooperative communication system. Mean while, it provided simulation results of upper-bound error-bit-rate in both Rayleigh block fading and fast fading channel system. Furthermore, comparing with traditional coding cooperative solution with none cooperative solution, the computer simulation results indicated that if cooperative channel is in expected condition, improved network convlutional cooperative communication solution will enhance the system performance in both clients' uplink symmetry and asymmetry scenarios in a slow fading channel path. When uplink channels are in the same condition, the coding cooperative communication improves 8-9dB within the system. When uplink channel is in asymmetry state, coding cooperative solution is more effective for clients with channel in better condition. However, the solution provided in this article has relatively less side-effects on clients with channel in better condition, and it has remarkable improvements on overall performance for both clients .