To broaden the application scenario and reduce energy consumption, we propose an energy-efficient fixed-gain (FG) amplify-and-forward (AF) relay assisted orthogonal frequency-division multiplexing with index modulation (OFDM-IM) scheme in this letter. The proposed system needs neither instantaneous channel state information (CSI) nor complicated processing at the relay node. It operates based on the power allocation scheme that minimizes the sum of transmit power at both source and relay node, given an outage probability constraint. Through a series of problem transformation and simplification, we convert the original power allocation problem to its relaxed version and solve it using convex programming techniques. To reveal the computing efficiency of the proposed power allocation scheme, we analyze its computational complexity. Numerical simulations substantiate that the proposed optimization scheme has a neglectable loss compared with the brute force search, but the computational complexity can be considerably reduced.

中文翻译：

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具有索引调制的高能效固定增益 AF 中继辅助 OFDM

为了拓宽应用场景并降低能耗，我们在这封信中提出了一种节能的固定增益（FG）放大转发（AF）中继辅助正交频分复用索引调制（OFDM-IM）方案。所提出的系统既不需要瞬时信道状态信息（CSI），也不需要中继节点的复杂处理。它基于功率分配方案运行，该方案在给定中断概率约束的情况下最小化源节点和中继节点的发射功率总和。通过一系列的问题转换和简化，我们将原来的功率分配问题转化为它的宽松版本，并使用凸规划技术解决它。为了揭示所提出的功率分配方案的计算效率，我们分析了其计算复杂度。