Consider a memoryless relay channel, where the relay is connected to the destination with an isolated bit pipe of capacity C0. Let C(C0) denote the capacity of this channel as a function of C0. What is the critical value of C0 such that C(C0) first equals C(∞)? This is a long-standing open problem posed by Cover and named “The Capacity of the Relay Channel,” in Open Problems in Communication an...

In network information theory, the relay channel models a communication scenario where there is one or more relay nodes that can help the information transmission between the source and the destination. Although the capacity of the relay channel is still unknown even in the single-relay case, two fundamentally different relay schemes have been developed by (Cover and El Gamal, 1979) for such ch...

In this paper, the Gaussian relay channel with linear time-invariant relay filtering is considered. Based on spectral theory for stationary processes, the maximum achievable rate for this subclass of linear Gaussian relay operation is obtained in finite-letter characterization. The maximum rate can be achieved by dividing the overall frequency band into at most eight subbands and by making the ...

Noisy network coding is recently proposed for the general multi-source network by Lim, Kim, El Gamal and Chung. This scheme builds on compress-forward (CF) relaying but involves three new ideas, namely no Wyner-Ziv binning, relaxed simultaneous decoding and message repetition. In this paper, using the two-way relay channel as the underlining example, we analyze the impact of each of these ideas...

A relay channel consists of an input x,, a relay output yl, a cJmnnel output y, and a relay sender x2 (whose trasmission is allowed to depend on the past symbols y,). l%e dependence of the received symbols upm the inpnts is given by p(y,y,lx,,x,). ‘l%e channel is assumed to be memoryless. In this paper the following capacity theorems are proved. 1) Ifyisadegnukdformofy,,the.n C-m=Phx2) min(l(X,...

We study the Rayleigh fading relay channel. We first show that relay cooperation offers a small capacity increase with respect to the direct channel and then focus on studying the diversity-multiplexing tradeoff. We find a bound on the optimal diversity-rate function and establish that this bound is achieved by an adaptive version of the classical Markov coding scheme.

In this paper, the outage performance of automatic repeat request (ARQ) based opportunistic relaying is analyzed when the channel state information (CSI) for relay selection is outdated. The outage probability is derived in terms of correlation between SNR and outdated SNR of the channel from the selected relay to destination. It is shown that simulation results of the outage probability match ...

The discrete memoryless state-dependent relay channel (SD-RC) is considered in this study. Two main cases are investigated: SD-RC with non-causal channel state information (CSI) and SD-RC with causal CSI. In each case, the SD-RC with partial CSI at the source and the relay is considered. As special cases it includes three different situations in which perfect CSI is available: (i) only at the s...

We propose a joint network-channel coding scheme for the multiple-access relay channel. In this scenario, two users use a common relay which performs network coding. We show how a distributed Low-Density Parity-Check (LDPC) code can be applied as a joint network-channel code. The network-channel code is described by one single regular Tanner graph and is decoded with the iterative messagepassin...

In this study, compressed channel estimation method for sparse multipath two-way relay networks is investigated. Conventional estimation methods, e.g., Least Square (LS) and Minimum Mean Square Error (MMSE), are based on the dense assumption of relay channel and cannot exploit channel sparsity which has been verified by lots of channel measurements. Unlike the previous methods, we propose a com...