基于物理层网络编码的协作中继技术研究

发布时间：2018-04-25 09:28

本文选题：物理层网络编码 + 双向中继系统　；参考：《西北农林科技大学》2017年硕士论文

【摘要】：网络编码因其可从达到最大流-最小割的理论容量上限受到了学术界的广泛关注。协作通信是一种能利用虚拟天线技术获得分集增益的技术,已经被研究证明能够提高通信系统的性能。物理层网络编码作为网络编码的一个分支,其本身包含了协作思想,利用中间节点对信息进行处理,能提高系统的吞吐量,降低系统的中断概率。在无线协作通信系统中引入网络编码技术,可以进一步提升网络吞吐量、安全性和鲁棒性。本文探究了中继系统采用物理层网络编码时对系统容量的影响,并在此基础上,以最大化系统容量为目标研究了一种功率分配策略。另外,为确保数据传输的准确性,分析了基于物理层网络编码的双向中继系统的中断概率。主要工作如下:1.分析了基于物理层网络编码的双向中继系统的数学模型,分析了基于物理层网络编码的双向中继系统中源节点的接收信噪比,得出了信道容量的算术表达式。通过仿真实验,将基于物理层网络编码的双向中继系统与采用直接网络编码的双向中继系统和传统存储转发的双向中继系统的信道容量进行了对比。仿真结果表明,采用物理层网络编码的双向中继系统的信道容量高于采用直接网络编码的双向中继系统和传统的双向中继系统,并且当中继节点R处于源节点A、B正中间的位置时,信道容量取得最大值。2.以系统的信道容量为优化目标函数,在总传输功率受限的约束条件下对双向中继系统的资源分配问题进行了深入研究,得出了最优的功率分配策略并进行了仿真。实验表明,采用最优功率分配的基于PNC的双向中继系统的信道容量总是高于采用平均功率分配的基于PNC的双向中继系统的信道容量。3.研究了基于物理层网络编码的双向中继系统的中断性能。首先将双向中继系统的信息传输看作是两个不同方向的信息流,分别分析了它们的中断概率。最后将双向中继系统作为一个整体分析了整个系统的中断概率并计算得出了基于物理层网络编码的双向中继系统的中断概率的下界的表达式。仿真结果表明,双向中继系统的中断概率与系统的信噪比、中继节点的位置和系统的目标速率直接相关:随着信噪比的逐渐增大,节点A和节点B的中断概率均逐渐减小;当中继节点R位于A、B连线的正中间时,节点A和B中断概率相等且取得最小值,离中继节点较近的节点具更好的中断性能。
[Abstract]:Network coding has attracted much attention because of its theoretical capacity limit, which can reach the maximum flow-minimum cut. Cooperative communication is a kind of technology which can obtain diversity gain by using virtual antenna technology. It has been proved that it can improve the performance of communication system. As a branch of network coding, physical layer network coding contains the idea of cooperation. Using intermediate nodes to process information can improve the throughput of the system and reduce the interruption probability of the system. Network coding technology is introduced into wireless cooperative communication system, which can further improve network throughput, security and robustness. In this paper, the influence of physical layer network coding on the system capacity in relay system is discussed. Based on this, a power allocation strategy is proposed to maximize the system capacity. In addition, in order to ensure the accuracy of data transmission, the outage probability of bidirectional relay system based on physical layer network coding is analyzed. The main work is as follows: 1. The mathematical model of bidirectional relay system based on physical layer network coding is analyzed, and the receiving SNR of source node in bidirectional relay system based on physical layer network coding is analyzed, and the arithmetic expression of channel capacity is obtained. Through simulation experiments, the channel capacity of bidirectional relay system based on physical layer network coding is compared with that of bidirectional relay system using direct network coding and traditional storage and forwarding bidirectional relay system. The simulation results show that the channel capacity of bidirectional relay system using physical layer network coding is higher than that of bidirectional relay system using direct network coding and traditional bidirectional relay system. And when the relay node R is in the middle of the source node, the channel capacity reaches the maximum. 2. Taking the channel capacity of the system as the optimization objective function, the resource allocation problem of bidirectional relay system is deeply studied under the constraint of total transmission power, and the optimal power allocation strategy is obtained and simulated. The experimental results show that the channel capacity of bidirectional relay system based on PNC with optimal power allocation is always higher than that of bidirectional relay system based on PNC with average power allocation. The interrupt performance of bidirectional relay system based on physical layer network coding is studied. Firstly, the information transmission of bidirectional relay system is regarded as two information flows in different directions, and their outage probability is analyzed respectively. Finally, the interrupt probability of the whole system is analyzed as a whole and the lower bound of the outage probability of the bidirectional relay system based on the physical layer network coding is calculated. The simulation results show that the outage probability of the bidirectional relay system is directly related to the signal-to-noise ratio (SNR) of the system, the location of the relay node and the target rate of the system. With the increase of SNR, the outage probability of nodes A and B decreases gradually. When the relay node R is in the middle of the Agna B line, the outage probability of node A and B is equal and the minimum value is obtained, and the node close to the relay node has better interrupt performance.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN92

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