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arXiv 1108.6312cs.ITmath.IT
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计算对齐:无噪声累积的容量近似

Computation Alignment: Capacity Approximation without Noise Accumulation

Urs Niesen, Bobak Nazer, Phil Whiting

摘要:

考虑几个源节点在几层中继节点的帮助下通过无线网络通信到目的地节点。Avestimehr等人最近的工作已经将该网络的容量近似为加性间隙。实现这种容量近似的通信方案是基于压缩和转发的,从而导致在消息穿过网络时噪声累积。因此,近似间隙随网络深度线性增加。本文提出了一种计算对齐策略,可以接近一类分层的,时变的无线中继网络的容量的近似间隙是独立的网络深度。这种策略是基于计算和转发框架,使中继解码确定性功能的传输消息。单独地,计算和转发不足以接近容量,因为它会导致通过具有整数系数的信道来近似具有复值系数的无线信道的惩罚。在这里,通过仔细匹配跨时隙的信道实现以创建非常适合于计算和转发的整数值有效信道来规避这种惩罚。不同于先前的恒定间隙的结果,本文中获得的近似间隙也密切依赖于衰落统计,这被假定为独立同分布。瑞利

英文摘要:

Consider several source nodes communicating across a wireless network to a destination node with the help of several layers of relay nodes. Recent work by Avestimehr et al. has approximated the capacity of this network up to an additive gap. The communication scheme achieving this capacity approximation is based on compress-and-forward, resulting in noise accumulation as the messages traverse the network. As a consequence, the approximation gap increases linearly with the network depth. This paper develops a computation alignment strategy that can approach the capacity of a class of layered, time-varying wireless relay networks up to an approximation gap that is independent of the network depth. This strategy is based on the compute-and-forward framework, which enables relays to decode deterministic functions of the transmitted messages. Alone, compute-and-forward is insufficient to approach the capacity as it incurs a penalty for approximating the wireless channel with complex-valued coefficients by a channel with integer coefficients. Here, this penalty is circumvented by carefully matching channel realizations across time slots to create integer-valued effective channels that are well-suited to compute-and-forward. Unlike prior constant gap results, the approximation gap obtained in this paper also depends closely on the fading statistics, which are assumed to be i.i.d. Rayleigh.

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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