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Network coding for twoway relay channels using lattices,” in Telecommunications review vol
 Korea Advanced Institute of Science and Technology. Downloaded on May 21,2010 at 14:26:43 UTC from IEEE Xplore. Restrictions apply
"... Abstract—In this paper, we propose a network coding using a lattice for the twoway relay channel with two nodes communicating bidirectionally through a relay, which we call moduloandforward (MF). Our scheme extends the network coding in the binary channel to the Gaussian channel case, where XOR ..."
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Abstract—In this paper, we propose a network coding using a lattice for the twoway relay channel with two nodes communicating bidirectionally through a relay, which we call moduloandforward (MF). Our scheme extends the network coding in the binary channel to the Gaussian channel case, where XOR in the binary case is replaced by modΛ for the Gaussian case, where Λ is a highdimensional lattice whose shaping gain is close to optimal. If the relay node retransmits the received signal after the mod Λ operation, we can reduce the complexity compared to decodeandforward (DF) and can get a better power efficiency compared to amplifyandforward (AF). When the transmission powers of two nodes are different, we use superposition coding and partial decoding at the relay node. Finally, we plot and compare the sum rates of three different schemes, i.e., AF, DF, and MF. We show that by applying the proposed scheme, we can get better performance than AF and DF schemes under some conditions. I.
Twoway relaying over OFDM: Optimized tone permutation and power allocation
 in Proc. IEEE ICC
, 2008
"... Abstract—We consider an amplifyandforward scheme for twoway relaying over OFDM, in which two nodes wish to exchange information via a relay. Assuming full channel knowledge, we perform power allocation for the relay and both informationexchanging nodes, as well as tone permutation at the relay, ..."
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Cited by 31 (3 self)
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Abstract—We consider an amplifyandforward scheme for twoway relaying over OFDM, in which two nodes wish to exchange information via a relay. Assuming full channel knowledge, we perform power allocation for the relay and both informationexchanging nodes, as well as tone permutation at the relay, so as to maximize the sum capacity. A dual decomposition technique is employed for power allocation, while a greedy approach is proposed for tone permutation. In particular, we explore an interesting waterfilling behavior displayed by this power allocation solution. Numerical results demonstrate that substantial capacity gains are achieved by implementing the two proposed solutions, either individually or successively. I.
The capacity region of multiway relay channels over finite fields with full data exchange
 IEEE Trans. Inf. Theory
, 2011
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Approximate capacity of the twoway relay channel: a deterministic approach
 in Proc. 46th Annu. Allerton Conf. Communication, Control, and Computing
, 2008
"... Abstract—We study the capacity of the fullduplex bidirectional (or twoway) relay channel with two nodes and one relay. The channels in the forward direction are assumed to be different (in general) than the channels in the backward direction, i.e. channel reciprocity is not assumed. We use the rec ..."
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Cited by 22 (3 self)
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Abstract—We study the capacity of the fullduplex bidirectional (or twoway) relay channel with two nodes and one relay. The channels in the forward direction are assumed to be different (in general) than the channels in the backward direction, i.e. channel reciprocity is not assumed. We use the recently proposed deterministic approach to capture the essence of the problem and to determine a good transmission and relay strategy for the Gaussian channel. Depending on the ratio of the individual channel gains, we propose to use either a simple amplifyandforward or a particular superposition coding strategy at the relay. We analyze the achievable rate region and show that the scheme achieves to within 3 bits the cutset bound for all values of channel gains. I.
Approximate capacity region of the twopair bidirectional gaussian relay network
 in Proc. IEEE Int. Symp. Inf. Theory, Seoul
, 2009
"... Abstract—We study the capacity of the Gaussian twopair fullduplex directional (or twoway) relay network with a singlerelay supporting the communication of the pairs. This network is a generalization of the well known bidirectional relay channel, where we have only one pair of users. We propose a ..."
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Cited by 17 (6 self)
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Abstract—We study the capacity of the Gaussian twopair fullduplex directional (or twoway) relay network with a singlerelay supporting the communication of the pairs. This network is a generalization of the well known bidirectional relay channel, where we have only one pair of users. We propose a novel transmission technique which is based on a specific superposition of lattice codes and random Gaussian codes at the source nodes. The relay attempts to decode the Gaussian codewords and the superposition of the lattice codewords of each pair. Then it forwards this information to all users. We analyze the achievable rate of this scheme and show that for all channel gains it achieves to within 2 bits/sec/Hz per user of the cutset upper bound on the capacity region of the twopair bidirectional relay network. I.
An optimal coding strategy for the binary multiway relay channel
 IEEE Commun. Lett
, 2010
"... Abstract—We derive the capacity of the binary multiway relay channel, in which multiple users exchange messages at a common rate through a relay. The capacity is achieved using a novel functionaldecodeforward coding strategy. In the functionaldecodeforward coding strategy, the relay decodes func ..."
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Cited by 17 (7 self)
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Abstract—We derive the capacity of the binary multiway relay channel, in which multiple users exchange messages at a common rate through a relay. The capacity is achieved using a novel functionaldecodeforward coding strategy. In the functionaldecodeforward coding strategy, the relay decodes functions of the users ’ messages without needing to decode individual messages. The functions to be decoded by the relay are defined such that when the relay broadcasts the functions back to the users, every user is able to decode the messages of all other users. Index Terms—Capacity, functionaldecodeforward, multiway relay channel, binary, coding.
Capacity region of the deterministic multipair bidirectional
, 903
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Lattice codes for the Gaussian relay channel: DecodeandForward and CompressandForward
, 2013
"... Lattice codes are known to achieve capacity in the Gaussian pointtopoint channel, achieving the same rates as i.i.d. random Gaussian codebooks. Lattice codes are also known to outperform random codes for certain channel models that are able to exploit their linearity. In this paper, we show that ..."
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Cited by 13 (3 self)
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Lattice codes are known to achieve capacity in the Gaussian pointtopoint channel, achieving the same rates as i.i.d. random Gaussian codebooks. Lattice codes are also known to outperform random codes for certain channel models that are able to exploit their linearity. In this paper, we show that lattice codes may be used to achieve the same performance as known i.i.d. Gaussian random coding techniques for the Gaussian relay channel, and show several examples of how this may be combined with the linearity of lattices codes in multisource relay networks. In particular, we present a nested lattice list decoding technique in which lattice codes are shown to achieve the decodeandforward (DF) rate of single source, single destination Gaussian relay channels with one or more relays. We next present two examples of how this DF scheme may be combined with the linearity of lattice codes to achieve new rate regions which for some channel conditions outperform analogous known Gaussian random coding techniques in multisource relay channels. That is, we derive a new achievable rate region for the twoway relay channel with direct links and compare it to existing schemes, and derive a new achievable rate region for the multiple access relay channel. We furthermore present a lattice compressandforward (CF) scheme for the Gaussian relay channel which exploits a lattice Wyner–Ziv binning scheme and achieves the same rate as the Cover–El Gamal CF rate evaluated for Gaussian random codes. These results suggest that structured/lattice codes may be used to mimic, and sometimes outperform, random Gaussian codes in general Gaussian networks.
Multiuser twoway relaying for interference limited systems
 the IEEE International Conference on Communications, ICC’08
"... Abstract—We investigate multiuser twoway relaying strategies for interference limited systems where multiple pairs of users exchange information with their partners via an intermediate relay node in a twophase communication scenario. To take advantage of the bidirectional communication structure, ..."
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Cited by 11 (2 self)
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Abstract—We investigate multiuser twoway relaying strategies for interference limited systems where multiple pairs of users exchange information with their partners via an intermediate relay node in a twophase communication scenario. To take advantage of the bidirectional communication structure, we propose that each pair of users share a common spreading signature instead of using distinct signatures as in a traditional CDMA setting. We design the jointly demodulateandXOR forward (JDXORF) relaying scheme and derive the decision rule which enables the relay to generate the XORed symbol upon reception of the superposition of user symbols. When the relay has limited computational capability, amplifyandforward relaying can be applied instead. We evaluate the BER performance for the proposed relaying schemes and show that they significantly outperform the traditional “oneway ” CDMA systems. I.