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arXiv 0901.4379cs.ITmath.IT
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遍历干涉对齐

Ergodic Interference Alignment

Bobak Nazer, Michael Gastpar, Syed A. Jafar, Sriram Vishwanath

摘要:

针对时变衰落的K用户干扰信道,提出了一种新的通信策略--遍历干扰对齐。在任何特定的时间,每个接收器将看到发射信号加上噪声的叠加。这种情况的标准方法导致每个发射机-接收机对实现与其无干扰遍历容量的1/K成比例的速率。然而,给定两个精心选择的时间索引,来自干扰用户的信道系数可以被精确地抵消。通过将这两个观测值相加,每个接收机可以在没有任何干扰的情况下获得其所需的信号。如果信道增益具有独立的、均匀的相位,则该技术允许每个用户在任何信噪比下实现至少1/2的无干扰遍历容量。现有的干扰对准技术只能在信噪比趋于无穷大时才能达到这种性能。扩展的情况下,每个接收器希望从一个以上的发射机的消息,以及“X通道”的情况下(有两个接收器),每个发射机有一个独立的消息,每个接收器。最后,它是如何推广这种策略超越高斯信道模型。对于一类有限域干扰信道,该方法得到了遍历容量域。

英文摘要:

This paper develops a new communication strategy, ergodic interference alignment, for the K-user interference channel with time-varying fading. At any particular time, each receiver will see a superposition of the transmitted signals plus noise. The standard approach to such a scenario results in each transmitter-receiver pair achieving a rate proportional to 1/K its interference-free ergodic capacity. However, given two well-chosen time indices, the channel coefficients from interfering users can be made to exactly cancel. By adding up these two observations, each receiver can obtain its desired signal without any interference. If the channel gains have independent, uniform phases, this technique allows each user to achieve at least 1/2 its interference-free ergodic capacity at any signal-to-noise ratio. Prior interference alignment techniques were only able to attain this performance as the signal-to-noise ratio tended to infinity. Extensions are given for the case where each receiver wants a message from more than one transmitter as well as the "X channel" case (with two receivers) where each transmitter has an independent message for each receiver. Finally, it is shown how to generalize this strategy beyond Gaussian channel models. For a class of finite field interference channels, this approach yields the ergodic capacity region.

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