On the capacity of the half-duplex diamond channel
On the capacity of the half-duplex diamond channel
复制标题
浅谈半双工钻石通道的容量
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
A. Khandani
中科院分区：
文献类型：
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作者：
H. Bagheri;A. Motahari;A. Khandani
本文考虑了一种由源S和目的D通过两个互不干扰的半双工中继R1和R2连接而成的双跳通信系统。在信息论的文献中，这种结构被称为钻石通道。在此设置中，有四种传输模式，即1)S发送，R1和R2收听（广播模式），2)S发送，R1收听，同时R2发送，D收听。3) S发送，R2监听，同时R1发送，D监听。4) R1、R2发射，D监听（多址模式）。假设所有发射机的功率约束都是恒定的，定义了一个参数Δ，它捕获了信道的一些重要特征。证明了在Δ=0时，信道的容量可以通过连续中继获得，即以连续方式使用上面定义的模式2和3。当Δ≠0时，此策略可能与通道容量存在无限差距。为了达到接近容量0.71位的速率，表明Δ > 0和Δ < 0的情况应该区别对待。利用基于与割集界相关的线性规划对偶问题的新上界，证明了对于Δ < 0和Δ >分别需要增加一个广播模式（模式1）或多址模式（模式4）来增强连续中继策略。此外，在平均功率限制下，上述策略可以达到接近信道容量3.6比特的速率。
In this paper, a dual-hop communication system composed of a source S and a destination D connected through two non-interfering half-duplex relays, R1 and R2, is considered. In the literature of Information Theory, this configuration is known as the diamond channel. In this setup, four transmission modes are present, namely: 1) S transmits, and R1 and R2 listen (broadcast mode), 2) S transmits, R1 listens, and simultaneously, R2 transmits and D listens. 3) S transmits, R2 listens, and simultaneously, R1 transmits and D listens. 4) R1, R2 transmit, and D listens (multiple-access mode). Assuming a constant power constraint for all transmitters, a parameter Δ is defined, which captures some important features of the channel. It is proven that for Δ=0 the capacity of the channel can be attained by successive relaying, i.e, using modes 2 and 3 defined above in a successive manner. This strategy may have an infinite gap from the capacity of the channel when Δ≠0. To achieve rates as close as 0.71 bits to the capacity, it is shown that the cases of Δ > 0 and Δ < 0 should be treated differently. Using new upper bounds based on the dual problem of the linear program associated with the cut-set bounds, it is proven that the successive relaying strategy needs to be enhanced by an additional broadcast mode (mode 1), or multiple access mode (mode 4), for the cases of Δ < 0 and Δ > 0, respectively. Furthermore, it is established that under average power constraints the aforementioned strategies achieve rates as close as 3.6 bits to the capacity of the channel.