Relay node selection and combination ratio for amplify-and-forward OFDM-UWB communication

doi:10.1016/S1005-8885(15)60651-3

Acta Metallurgica Sinica(English letters) ›› 2015, Vol. 22 ›› Issue (3): 41-48.doi: 10.1016/S1005-8885(15)60651-3

Relay node selection and combination ratio for amplify-and-forward OFDM-UWB communication

Guo Yong, Huang Liang

School of Electronics and Information Engineering, Beijing Jiaotong University

收稿日期:2014-09-22 修回日期:2015-01-21 出版日期:2015-06-30 发布日期:2015-06-24
通讯作者: Guo Yong, E-mail: yguo@m.bjtu.edu.cn. E-mail:yguo@m.bjtu.edu.cn
基金资助:
National Natural Science Fundation of China (61271201), the Fundamental Research Funds for the Central Universities of China (W12JB00060 and 2013JBM016).

Relay node selection and combination ratio for amplify-and-forward OFDM-UWB communication

Guo Yong, Huang Liang

School of Electronics and Information Engineering, Beijing Jiaotong University

Received:2014-09-22 Revised:2015-01-21 Online:2015-06-30 Published:2015-06-24
Contact: Guo Yong, E-mail: yguo@m.bjtu.edu.cn. E-mail:yguo@m.bjtu.edu.cn
Supported by:
National Natural Science Fundation of China (61271201), the Fundamental Research Funds for the Central Universities of China (W12JB00060 and 2013JBM016).

摘要/Abstract

摘要： 正交频分复用-超宽带 (OFDM-UWB)信号的带宽很大，加之室内信道的复杂性，UWB信道为频率选择性信道。UWB通信的速率和可靠性必将受到影响。本文提出了中继放大转发方案来降低频率选择性信道对通信容量和可靠性的影响。使用中继的合作通信可以获得容量增益和分集增益。本文首先研究了为了获得最大容量增益，中继节点选择和合并比的确定。容量增益不仅与中继链路的信噪比有关，还依赖于直达链路和中继链路的信道频率响应有关。两个两路的频率响应相似度越大，容量增益越大。最佳的中继节点和最大合并比通过对容量公式求导获得，求解二次导数方程能够获得最优的中继节点和最佳合并比。第二部分研究了获取最大分集增益，中继节点选择和合并比的确定。如果直达链路和中继链路的合成信道的频率响应深度中衰落的子信道到越少则分集增益越大。为了简化问题的计算，将问题分成两步：第一步先根据SNR(f)的平均值和方差确定中继节点；第二步对该节点求解最佳合并比。数字仿真证明了我们的方案在获取容量增益和分集增益有效性。

关键词: 合作通信，放大转发，中继选择，合并比，正交频分复用-超宽带

Abstract: Due to its large bandwidth and the complexity of indoor environment, the UWB channel is frequency selective, which affects the data rate and reliability of UWB communi- cation. This paper proposes an amplify-forward relay scheme to mitigate this reliability problem. The relay can be used to acquire capacity gain and diversity gain just like MIMO. The first investigation focuses on the relay-node selection criterion and combination ration for capacity gain. Capacity gain depends on the correlation of frequency responses between direct link and relay link in addition to relay link SNR. Increased similarity of the two frequency responses increases capacity gain. Capacity gain’s best relay and combination ratio are found by taking the derivative of the capacity equation. Solution of the quadratic derivative equation of ratio finds the optimal ratios for every potential relay node. The second investigation focuses on relay- node selection criterion and combination ratio for diversity gain respectively.Higher diversity gain corresponds to less-deep-faded subchannels of combined signal. Reduced computation divides the problem into two steps: The first step selects the relay node according to the criterion that is dependent on the average of SNR(f) and variance of SNR(f) . The second step solves the combination ratio-optimization problem for optimal ratio. Numerical simulation shows that our scheme is effective in pursuit of capacity gain and of diversity gain.

Key words: Cooperative communication, amplify-and-forward, relay selection, combination ratio, OFDM-UWB

Guo Yong, Huang Liang. Relay node selection and combination ratio for amplify-and-forward OFDM-UWB communication[J]. Acta Metallurgica Sinica(English letters), 2015, 22(3): 41-48.

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Relay node selection and combination ratio for amplify-and-forward OFDM-UWB communication

Relay node selection and combination ratio for amplify-and-forward OFDM-UWB communication

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