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Linear precoding designs for amplifyandforward multiuser twoway relay systems
 IEEE Trans. Wireless Commun
, 2012
"... Abstract—Twoway relaying can improve spectral efficiency in twouser cooperative communications. It also has great potential in multiuser systems. A major problem of designing a multiuser twoway relay system (MUTWRS) is transceiver or precoding design to suppress cochannel interference. This pap ..."
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Abstract—Twoway relaying can improve spectral efficiency in twouser cooperative communications. It also has great potential in multiuser systems. A major problem of designing a multiuser twoway relay system (MUTWRS) is transceiver or precoding design to suppress cochannel interference. This paper aims to study linear precoding designs for a cellular MUTWRS where a multiantenna base station (BS) conducts bidirectional communications with multiple mobile stations (MSs) via a multiantenna relay station (RS) with amplifyandforward relay strategy. The design goal is to optimize uplink performance, including total meansquare error (TotalMSE) and sum rate, while maintaining individual signaltointerferenceplusnoise ratio (SINR) requirement for downlink signals. We show that the BS precoding design with the RS precoder fixed can be converted to a standard second order cone programming (SOCP) and the optimal solution is obtained efficiently. The RS precoding design with the BS precoder fixed, on the other hand, is nonconvex and we present an iterative algorithm to find a local optimal solution. Then, the joint BSRS precoding is obtained by solving the BS precoding and the RS precoding alternately. Comprehensive simulation is conducted to demonstrate the effectiveness of the proposed precoding designs. Index Terms—MIMO precoding, twoway relaying, nonregenerative relay, minimum meansquareerror (MMSE), convex optimization. I.
Linear precoding for multipair twoway MIMO relay systems with maxmin fairness
 IEEE Trans. Signal Process
, 2012
"... Abstract—Twoway relaying has demonstrated significant gain in spectral efficiency by applying network coding when a pair of source nodes exchange information via a relay node. This paper is concerned with the scenario where multiple pairs of users exchange information through a common relay node e ..."
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Cited by 15 (5 self)
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Abstract—Twoway relaying has demonstrated significant gain in spectral efficiency by applying network coding when a pair of source nodes exchange information via a relay node. This paper is concerned with the scenario where multiple pairs of users exchange information through a common relay node equipped with multiple antennas. We aim to design linear precoding at the relay based on amplifyandforward strategy. The goal is to maximize the minimum achievable rate among all the users subject to a peak relay power constraint so as to achieve the maxmin fairness. We first convert this nonconvex problem into a series of semidefinite programming problems using bisection search and certain transformation techniques. A quasioptimal solution is then obtained by using semidefinite relaxation (SDR). To reduce the design complexity, we further introduce a pairwise zeroforcing (ZF) structure that eliminates the interference among different user pairs. By applying this structure, the precoding design problem is simplified to a power allocation problem which can be optimally solved. A simplified power allocation algorithm is also proposed. Simulation results show that the proposed SDRbased precoding not only achieves high minimum user rate but also maintains good sumrate performance when compared with existing schemes. It is also shown that the proposed pairwise ZF precoding with simplified power allocation strikes a good balance between performance and complexity. Index Terms—Multipleinput multipleoutput (MIMO), multiuser, nonregenerative relay, precoding, twoway relaying. I.
LargeScale Multipair TwoWay Relay Networks
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Cited by 2 (0 self)
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N.B.: When citing this work, cite the original article. ©2013 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Twoway relay beamforming design: Proportional fair and maxmin rate fair approaches using POTDC
 in Proc. IEEE Int. Conf. Acoust., Speech, Signal Process. (ICASSP
"... The challenge in designing relay beamforming in twoway relaying systems is the nonconvex nature of the corresponding optimization problem. In this work, we concentrate on the mathematical issues of such design for the cases when the maxmin rate and proportional fairness are used as the design cr ..."
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The challenge in designing relay beamforming in twoway relaying systems is the nonconvex nature of the corresponding optimization problem. In this work, we concentrate on the mathematical issues of such design for the cases when the maxmin rate and proportional fairness are used as the design criteria. We show that the corresponding optimization problems belong to the class of differenceofconvex functions (DC) programming problems. Due to the specific structure of the corresponding DC problems, they can be efficiently addressed by using the polynomialtime DC (POTDC) algorithm which guarantees to find the KarushKuhnTucker (KKT) optimal point in polynomialtime. We have also shown earlier that the question of global optimality of the POTDC algorithm boils down to a simple numerical convexity check for a certain onedimensional optimal value function. Index Terms — Differenceofconvex functions optimiza
A Hybrid Beamforming Scheme for a Special Study of Non Regenerative Multiantenna MultiGroup MultiWay Relaying
"... Abstract — We consider a transceiver beamforming design problem for nonregenerative multiantenna multigroup multiway relaying channel (MGMWRC) when the number of communication phases to complete the full data exchange equals to the maximum number of nodes among all groups. The first phase is mul ..."
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Abstract — We consider a transceiver beamforming design problem for nonregenerative multiantenna multigroup multiway relaying channel (MGMWRC) when the number of communication phases to complete the full data exchange equals to the maximum number of nodes among all groups. The first phase is multipleaccess (MAC) and the other phases are broadcast (BC). In each BC phase, the relay station (RS) does not decode streaming data from all nodes and applies beamforming scheme to its received data before sending to all nodes. We propose a hybrid beamforming scheme that combines Minimum Variance Distortion Response (MVDR)Matched Filter (MF) schemes and Coherent Combining (CC) scheme for bidirectional pairs of odd users in MGMWRC. The average sum rate and symbol error rate simulation results are provided to compare the performance of the proposed scheme and all conventional schemes under 3 types of loads.
Generalized Quadratically Constrained Quadratic Programming and its Applications in Array Processing and Cooperative Communications
, 2013
"... In this thesis, we introduce and solve a particular generalization of the quadratically constrained quadratic programming (QCQP) problem which is frequently encountered in the fields of communications and signal processing. Specifically, we consider such generalization of the QCQP problem which ca ..."
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In this thesis, we introduce and solve a particular generalization of the quadratically constrained quadratic programming (QCQP) problem which is frequently encountered in the fields of communications and signal processing. Specifically, we consider such generalization of the QCQP problem which can be precisely or approximately recast as the differenceofconvex functions (DC) programming problem. Although the DC programming problem can be solved through the branchandbound methods, these methods do not have any worstcase polynomial time complexity guarantees.
NonRegenerative MultiWay Relaying: Combining the Gains of Network Coding and Joint Processing
"... In this paper, we consider a nonregenerative multigroup multiway relaying scenario in which each group consists of multiple halfduplex nodes. Each node wants to share its data with all other nodes within its group. The transmissions are performed via an intermediate nonregenerative halfduplex ..."
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In this paper, we consider a nonregenerative multigroup multiway relaying scenario in which each group consists of multiple halfduplex nodes. Each node wants to share its data with all other nodes within its group. The transmissions are performed via an intermediate nonregenerative halfduplex multiantennarelay station, termed RS, which spatially separates the different groups. In our proposal, all nodes simultaneously transmit to RS during a common multiple access phase and RS retransmits linearly processed versions of the received signals back to the nodes during multiple broadcast (BC) phases. We propose a novel transmit strategy which exploits analog network coding (ANC) and efficientlycombines spatial transceive processing at RS with joint receive processing at each node over multiple BC phases. A closedform solution for an ANC aware relay transceive filter is introduced and closedform solutions for the joint receive processing filters at the nodes are presented. Furthermore, selfinterference cancellation and successive interference cancellation are exploited at the nodes to improve the joint receive processing. By numerical results, it is shown that the proposed transmit strategy significantly outperforms existing multiway strategies.
1 Design of Binary Network Codes for Multiuser Multiway Relay Networks
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