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arXiv 1208.2116cs.ITmath.IT
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高斯双向中继信道容量域的外界

Outer Bounds for the Capacity Region of a Gaussian Two-way Relay Channel

Ishaque Ashar K., Prathyusha V., Srikrishna Bhashyam, Andrew Thangaraj

摘要:

我们考虑一个三节点半双工高斯中继网络,其中两个节点(比如说$a$,$b$)希望相互通信,第三个节点充当这种双向通信的中继。研究了双向通信中可能的速率对$(R_a, R_b)$的外边界和可达速率区域。半双工节点的模式(发送或接收)一起指定网络的状态。中继协议使用特定的状态序列和每个状态的编码方案。在本文中,我们首先得到了一个外界的速率区域的所有可实现的$(R_a,R_b)$的基础上半双工割集界。这个外边界可以通过求解线性规划来数值计算。证明了在外部边界的边界上的任何点上,仅使用网络的六个状态中的四个。然后,我们将其与各种已知协议的可实现速率区域进行比较。我们考虑两种协议:(1)在一个状态下发送的所有消息都用同一状态下接收到的信号进行解码的协议,以及(2)在一个状态下接收到的信息也可以存储并用作辅助信息来解码未来状态下的消息的协议。各种结论得出的重要性,使用所有的国家,使用边信息,并选择在继电器的处理。然后,两个分析外边界(相对于一个优化问题配方)推导。使用分析的外界,我们得到的对称容量在0.5比特的一些信道条件下,节点a和b之间的直接链接是弱的。

英文摘要:

We consider a three-node half-duplex Gaussian relay network where two nodes (say $a$, $b$) want to communicate with each other and the third node acts as a relay for this twoway communication. Outer bounds and achievable rate regions for the possible rate pairs $(R_a, R_b)$ for two-way communication are investigated. The modes (transmit or receive) of the halfduplex nodes together specify the state of the network. A relaying protocol uses a specific sequence of states and a coding scheme for each state. In this paper, we first obtain an outer bound for the rate region of all achievable $(R_a,R_b)$ based on the half-duplex cut-set bound. This outer bound can be numerically computed by solving a linear program. It is proved that at any point on the boundary of the outer bound only four of the six states of the network are used. We then compare it with achievable rate regions of various known protocols. We consider two kinds of protocols: (1) protocols in which all messages transmitted in a state are decoded with the received signal in the same state, and (2) protocols where information received in one state can also be stored and used as side information to decode messages in future states. Various conclusions are drawn on the importance of using all states, use of side information, and the choice of processing at the relay. Then, two analytical outer bounds (as opposed to an optimization problem formulation) are derived. Using an analytical outer bound, we obtain the symmetric capacity within 0.5 bits for some channel conditions where the direct link between nodes a and b is weak.

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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