协作通信网络中联合功率分配与中继选择算法的研究

发布时间：2019-04-15 21:44

【摘要】：协作通信技术通过建立一个虚拟的多输入多输出(Multiple Input Multiple Output,MIMO)系统实现空间分集,可以提高无线通信网络的容量、覆盖范围和鲁棒性。在协作通信网络中,常用的中继协议有放大转发(Amplify-and-forward,AF)、解码转发(Decode-and-forward,DF)和编码协作(Code Cooperation,CC),网络模型分为单向中继网络(One-Way Relay Network,OWRN)和双向中继网络(Two-Way Relay Network,TWRN)。相对OWRN系统,TWRN有更高的频谱利用率,但是系统由于自干扰的存在容易受到信道估计误差的影响。中继选择(Relay Selection,RS)和功率分配(Power Allocation,PA)是提高协作通信网络系统性能的两种主要方式。RS是指系统根据信道条件选择出最适合转发信号的中继节点,PA指对系统的总发送功率进行合理的调配以实现系统性能的最优化。本文深入研究了TWRN的联合RS和PA算法。一方面,根据瞬时信道状态信息,提出了传统双向中继网络(Conventional TWRN,C-TWRN)和能量收集双向中继网络(Energy Harvesting TWRN,EH-TWRN)的几种联合RS和PA算法,提升TWRN系统性能;另一方面,研究了信道估计误差对TWRN系统功率消耗、传输速率和误码率的影响。论文的主要安排如下:(1)在传统AF-TWRN系统,提出了以最大化和速率为目标的联合RS和PA算法。首先利用瞬时信道状态信息得出TWRN两条通信链路的端到端信噪比(Signal-to-Noise Ratio,SNR),并获得了每个中继节点对应的最优功率分配,然后比较每一个中继节点可以实现的系统传输速率,最后选择出性能最优的中继节点转发信号。在此基础上,提出了中继功率限制情况下的联合RS和PA算法,极大的降低中继的发送功率。(2)在传统AF-TWRN系统中,提出了信道估计误差存在时以最小化功率消耗的联合RS和PA算法。利用Karush-Kuhn-Tucker(7)KKT(8)最优化条件,求得了系统最优功率分配,并选择出使系统总功率消耗最少的中继节点。最后比较了不同信道估计误差情况下,TWRN满足业务要求时的发送功率。(3)在EH-TWRN系统中,基于功率分割协议(Power Splitting-based Relaying,PSR)提出了系统在完美信道估计和非完美信道估计情况下的高能效联合RS和PA算法,获得了系统中每个中继节点最优的能量收集比例和对应的两个信源的最优功率分配。分析表明,与C-TWRN相比,EH-TWRN明显降低了系统的功率消耗;同样,随着信道估计误差的增大,EH-TWRN系统的功率消耗增加。(4)在EH-TWRN系统中,基于两条通信链路的SNR平衡准则,提出了最优的联合RS和PA算法。分析表明,相对传统的RS和PA算法,本文提出的方法可以实现最大的传输速率,在此基础上分析了信道估计误差对系统传输速率和误码率的影响。
[Abstract]:Cooperative communication technology can improve the capacity, coverage and robustness of wireless communication networks by establishing a virtual multi-input multiple-output (Multiple Input Multiple Output,MIMO) system to realize spatial diversity. In cooperative communication networks, the commonly used relay protocols are amplified forwarding (Amplify-and-forward,AF), decoding and forwarding (Decode-and-forward,DF) and coded collaboration (Code Cooperation,CC). The network model is divided into one-way relay network (One-Way Relay Network,). OWRN) and two-way trunking network (Two-Way Relay Network,TWRN). Compared with OWRN system, TWRN has higher spectral efficiency, but the system is vulnerable to channel estimation error due to the existence of self-interference. Relay selection (Relay Selection,RS) and Power allocation (Power Allocation,PA) are two main ways to improve the performance of cooperative communication network systems. RS refers to the selection of relay nodes that are most suitable for forwarding signals according to channel conditions. PA refers to the reasonable allocation of the total transmission power of the system to optimize the performance of the system. In this paper, the joint RS and PA algorithms of TWRN are studied in depth. On the one hand, according to the instantaneous channel state information, several combined RS and PA algorithms of traditional bidirectional relay network (Conventional TWRN,C-TWRN) and energy collection bidirectional relay network (Energy Harvesting TWRN,EH-TWRN) are proposed to improve the performance of TWRN system. On the other hand, the influence of channel estimation error on power consumption, transmission rate and bit error rate (BER) of TWRN system is studied. The main contents of this paper are as follows: (1) in the traditional AF-TWRN system, a joint RS and PA algorithm is proposed, which aims at maximization and rate. Firstly, the end-to-end signal-to-noise ratio (Signal-to-Noise Ratio,SNR) of the two TWRN communication links is obtained by using the instantaneous channel state information, and the optimal power allocation for each relay node is obtained. Then the transmission rate of each relay node can be compared. Finally, the relay node with the best performance is selected to forward the signal. On the basis of this, a joint RS and PA algorithm with limited relay power is proposed, which greatly reduces the transmission power of relay. (2) in traditional AF-TWRN system, the proposed algorithm can reduce the transmission power of relay greatly. A joint RS and PA algorithm is proposed to minimize power consumption in the presence of channel estimation errors. By using the Karush-Kuhn-Tucker (7) KKT (8) optimization condition, the optimal power allocation of the system is obtained, and the relay nodes which make the total power consumption of the system least are selected. Finally, the transmission power of TWRN with different channel estimation errors is compared. (3) in EH-TWRN system, based on power division protocol (Power Splitting-based Relaying,), the transmission power is compared. PSR) proposed an energy efficient combined RS and PA algorithm for the system with perfect channel estimation and imperfect channel estimation, and obtained the optimal energy collection ratio for each relay node and the optimal power allocation for the corresponding two sources. The analysis shows that compared with C-TWRN, EH-TWRN significantly reduces the power consumption of the system. Similarly, with the increase of channel estimation error, the power consumption of EH-TWRN system increases. (4) in EH-TWRN system, based on the SNR equilibrium criterion of two communication links, an optimal joint RS and PA algorithm is proposed. The analysis shows that compared with the traditional RS and PA algorithms, the method proposed in this paper can achieve the maximum transmission rate. Based on this, the influence of channel estimation error on the transmission rate and bit error rate (BER) of the system is analyzed.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN915.0

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