We investigate a joint design of linear precoders and receivers for multiple-input multiple-output non-simultaneous two-way relaying (NS-TWR). Unlike conventional two-way relaying, the base station in NS-TWR performs two-way relaying with two different users - a transmit-only user and a receive-only user (RUE). The RUE experiences back-propagating interference (BI). The proposed design cancels this BI and provides beamforming gain over existing designs. For NS-TWR, we maximize the weighted sum-rate (WSR) through joint power allocation, by solving a sequence of geometric programs. The precoder and the receiver designs as well as the power allocation program are then extended for a multi-user system with multiple transmit-only and receive-only users. With exhaustive simulations, we show that the proposed design provides significantly better WSR than the existing ones. The proposed design is also evaluated in a cellular framework using realistic path loss models, to assess the system-level performance gain achievable. © 2002-2012 IEEE.

Bhaskar Ramamurthi

Department of Electrical Engineering

Channel coding

Channel Estimation

Communication channels (information theory)

MIMO systems

Mobile security

Telecommunication networks

DIAGONALIZED CHANNELS

Exhaustive simulation

GEOMETRIC PROGRAM

MULTIPLE TRANSMIT

NON-SIMULTANEOUS

Power allocations

System-level performance

WEIGHTED SUM-RATE

Design

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IIT Madras

Joint Precoder and Receiver Design for AF Non-Simultaneous Two-Way MIMO Relaying

IEEE Transactions on Wireless Communications

We consider a cellular system with amplify-and-forward (AF) nonconcurrent two-way relaying (ncTWR), where a base station serves a transmit-only user and a receive-only user. Most of the state-of-the-art transceiver designs for AF multiple-input multiple-output (MIMO) ncTWR optimize a system-wide objective function subject to the transmit power constraints. Transceiver designs that incorporate quality-of-service (QoS) constraints are not well investigated in ncTWR literature. In this paper, we design a MIMO AF transceiver that maximizes weighted sum-rate (WSR) while guaranteeing the QoS constraints that are cast as per-stream rate required by two ncTWR users. The WSR maximization is a nonconvex problem due to its nonconvex objective. We solve this problem by separately approximating the objective at low and high signal-to-noise ratios (SNRs), with each approximation cast as a geometric program. With extensive numerical evaluations, we first demonstrate the improved performance of the proposed transceiver over existing designs without QoS constraints. We later investigate the effect of QoS constraints on the system WSR. © 1967-2012 IEEE.

IEEE Transactions on Vehicular Technology

Transceiver Design for Nonconcurrent Two-Way MIMO AF Relaying with QoS Guarantees

Transceiver designs for multiple-input multiple-output (MIMO) two-way relaying are being actively explored. Most of the state-of-the-art studies optimize a system-wide objective function subject to the transmit power constraints on the two source nodes and the relay. Transceiver designs with quality-of-service (QoS) constraints have lacked attention in two-way relaying literature. In this paper, we study a MIMO transceiver design, based on the generalized singular value decomposition, that allocates power at the source and relay nodes to optimize the following per-stream rate-constrained objectives: 1) network transmit power, and 2) sum-rate. In addition, we also maximize the rate of the transmit stream with the worst signal-to-noise ratio. Through extensive numerical evaluations, we demonstrate the superior performance of proposed design over the existing ones, not only with QoS constraints but also without them. © 2002-2012 IEEE.

Joint transceiver design for QoS-constrained MIMO two-way non-regenerative relaying using geometric programming

We consider an amplify-and-forward infrastructure non-concurrent two-way relaying (ncTWR) scenario where a base station serves a transmit-only user TUE and a receive-only user RUE. Unlike conventional two-way relaying, the RUE in ncTWR experiences back-propagating interference (BI). Uniform channel decomposition and Tomlinson-Harashima precoding improve the bit error rate (BER) of multiple-antenna-multiple-output (MIMO) systems. Inspired by these techniques, we design a transceiver to reduce BER of both users in MIMO ncTWR. This transceiver cancels BI of the RUE and uses spatial noise whitening filters, designed herein, to uniformly decompose MIMO channels of both TUE and RUE. This letter quantifies the improved BER of the proposed transceiver. © 2012 IEEE.

IEEE Wireless Communications Letters

Joint Transceiver Design for Non-Concurrent MIMO Two-Way AF Relaying

In conventional two-way relaying (TWR), it is assumed that a user has data to send and receive simultaneously from the base station (BS) via a relay. In cellular systems, data flow between the BS and a user is usually not simultaneous, e.g., a transmit-only user (say, TUE) may have uplink data to send in the multiple access (MAC) phase, but may not have downlink data to receive in the broadcast (BC) phase. Such one-way data flow will reduce TWR to spectrally inefficient one-way relaying. The multiple-input-multiple-output (MIMO) asymmetric TWR (ATWR) protocol considered here restores the two-way data flow via a relay. In ATWR, the BC phase following the MAC phase of a TUE is used to send downlink data to a receive-only user (say, RUE). However, the RUE will not be able to cancel the back-propagating interference. We design a structured precoder at the relay to cancel this interference. The proposed precoder also triangularizes the end-to-end MIMO channels. The channel triangularization reduces the weighted sum-rate maximization and relay power minimization problems to power allocation problems, which are then cast as geometric programs. Simulation results illustrate the effectiveness of the proposed precoder when compared with conventional solutions. © 2014 IEEE.

Fulltext

Linear precoders for nonregenerative asymmetric two-way relaying in cellular systems

Two-way relaying reduces the loss in spectral efficiency caused in a conventional half-duplex relay due to two channel uses per data unit transmitted to the destination. Two-way relaying is possible when two nodes exchange data simultaneously through a relay. In the case of cellular systems, data exchange between base station (BS) and users (UE) is usually not symmetric, e.g., a user (UE1) might have uplink data to transmit during multiple access (MAC) phase, but might not have downlink data to receive during broadcast (BC) phase. This asymmetry in data exchange will reduce the gains of two-way relaying. In the case of infrastructure relays, where there are multiple users communicating through a relay, we propose that the BC phase following the MAC phase of UE 1 be used by the relay to transmit downlink data to a second user (UE2). Conventional two-way relaying with symmetric MAC and BC phases must now be modified to asymmetric MAC (BS → RS ← UE1) and BC phases (BS ← RS → UE2), respectively. This will result in UE2 not being able to cancel the back-propagating interference in the usual way. We design precoders using conventional zero-forcing and linear minimum-mean-square-error criteria to mitigate the back-propagating interference at UE2 for an amplify-and-forward (AF) relay. We also propose a novel precoder appropriate for the asymmetric two-way relaying. The sum-rate performance of the proposed precoder is shown to be better than the conventional precoders. © 2013 IEEE.

IEEE International Conference on Communications

Precoder design for asymmetric multi-user two-way AF relaying in cellular systems

Definitions

V-Series Nerve Agent CVX

IEEE Communications Magazine

Cellular architecture and key technologies for 5G wireless communication networks

Multiuser Two-Way Non-Regenerative MIMO Relaying With Non-Concurrent Traffic

Joint precoder and receiver design for AF non-simultaneous two-way MIMO relaying

Journal	Data powered by TypesetIEEE Transactions on Wireless Communications
Publisher	Data powered by TypesetInstitute of Electrical and Electronics Engineers Inc.
ISSN	15361276
Open Access	No