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arXiv 0712.3277cs.ITmath.IT
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衰落信道下训练传输的容量和能量效率研究

On the Capacity and Energy Efficiency of Training-Based Transmissions over Fading Channels

Mustafa Cenk Gursoy

摘要:

在本文中,容量和能量效率的训练为基础的通信计划用于传输先验未知的瑞利块衰落信道进行了研究。在这些方案中,在接收端使用周期性发送的训练符号来获得信道衰落系数的最小均方误差(MMSE)估计。首先,考虑估计误差和发送信号的乘积被假定为高斯噪声的情况。在这种情况下,它示出,位能量的要求增长没有约束的信号-噪声比(SNR)为零,和最小的位能量是在一个非零的SNR值,低于它不应该操作。块长度的最小比特能量和SNR值的最小值达到的效果进行了研究。闪光灯的训练和传输方案进行了分析,并显示,以提高能源效率在低信噪比制度。在论文的第二部分中,基于训练的计划的容量和能量效率的信道输入时,受到峰值功率约束的影响。实现能力的输入结构的特点和最佳输入的幅度分布示出为离散的有限数量的质量点。通过数值分析得到了系统的容量、比特能量需求和最优资源分配策略。由于峰值约束的存在,当SNR降低到零时,比特能量再次无约束地增长。研究了采用固定峰值功率和零占空比的开关键控时能量效率的提高。训练为基础的和非相干传输方案的性能比较。

英文摘要:

In this paper, the capacity and energy efficiency of training-based communication schemes employed for transmission over a-priori unknown Rayleigh block fading channels are studied. In these schemes, periodically transmitted training symbols are used at the receiver to obtain the minimum mean-square-error (MMSE) estimate of the channel fading coefficients. Initially, the case in which the product of the estimate error and transmitted signal is assumed to be Gaussian noise is considered. In this case, it is shown that bit energy requirements grow without bound as the signal-to-noise ratio (SNR) goes to zero, and the minimum bit energy is achieved at a nonzero SNR value below which one should not operate. The effect of the block length on both the minimum bit energy and the SNR value at which the minimum is achieved is investigated. Flash training and transmission schemes are analyzed and shown to improve the energy efficiency in the low-SNR regime. In the second part of the paper, the capacity and energy efficiency of training-based schemes are investigated when the channel input is subject to peak power constraints. The capacity-achieving input structure is characterized and the magnitude distribution of the optimal input is shown to be discrete with a finite number of mass points. The capacity, bit energy requirements, and optimal resource allocation strategies are obtained through numerical analysis. The bit energy is again shown to grow without bound as SNR decreases to zero due to the presence of peakedness constraints. The improvements in energy efficiency when on-off keying with fixed peak power and vanishing duty cycle is employed are studied. Comparisons of the performances of training-based and noncoherent transmission schemes are provided.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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