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arXiv 1512.01751cs.ITmath.IT
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非理想CSI下K用户干扰信道的干扰对齐

Interference Alignment for the K-user Interference Channel with Imperfect CSI

Milad Johnny, Mohammad Reza Aref

摘要:

在本文中,我们探讨了信息理论方面的干扰对齐及其关系到信道状态信息(CSI)。针对$K-$用户干扰信道中不同用户间干扰变化规律不同的问题,提出了几种方法来调整干扰的某些部分,提高了分时方法的效果。对于更实际的情况下,当所有连接到同一目的地的信道链路具有相同的变化模式,我们找到了一个上限,并分析了它的大干扰信道网络。该结果表明,当网络的大小增加时,上限值变为$\frac{\sqrt{K}}{2}$。对于快衰落信道时,所有的信道具有相同的变化模式,我们表明,当直接链路具有不同的特征功能(信道置换或记忆),在没有一半的CSI(交叉链路)在发送器和接收器,可以实现$K/2$度的自由度(DoF)。通过逆证明,我们还证明了这是实现$\frac{K}{2}$最大DoF的最小信道信息。在整个工作中,这一事实已经被精确地证明了关于更一般的部分状态CSI和可实现的DoF的陈述。换句话说,对于我们发现的3用户全连接干扰信道,当$\frac{3}{2}$位于可实现的DoF时,我们不需要知道CSI的一半。同时,将结果推广到$K-$用户干扰信道的更一般形式,并通过逆证明,证明了其对信道状态的函数性是最优的。

英文摘要:

In this paper we explore the information-theoretic aspects of interference alignment and its relation to channel state information (CSI). For the $K-$user interference channel using different changing patterns between different users, we propose several methods to align some parts of interferences and to increase what is achieved by time sharing method. For more practical case when all the channel links connected to the same destination have the same changing pattern, we find an upper-bound and analyze it for the large interference channel network. This result shows that when the size of the network increases, the upper-bound value goes to $\frac{\sqrt{K}}{2}$. For the fast fading channel when all the channels have the same changing pattern, we show that when the direct links have different characteristic functions (channel permutation or memory), in the absence of half part of CSI (cross links) at both transmitters and receivers, one can achieve $K/2$ degrees-of-freedom (DoF). Also by the converse proof we show that this is the minimum channel information to achieve maximum DoF of $\frac{K}{2}$. Throughout this work, this fact has been pinpointed to prove statements about more general partial state CSI and achievable DoF. In other words, for the 3-user fully connected interference channel we find out while $\frac{3}{2}$ lies in achievable DoF, we don't need to know half part of the CSI. Also, the result has been extended to a more general form for $K-$user interference channel and through the converse proof, its functionality on channel state is proved to be optimum.

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