825 research outputs found
Rate Balancing in Full-Duplex MIMO Two-Way Relay Networks
Maximizing the minimum rate for a full-duplex multiple-input multiple-output
(MIMO) wireless network encompassing two sources and a two-way (TW) relay
operating in a two hop manner is investigated. To improve the overall
performance, using a zero-forcing approach at the relay to suppress the
residual self-interference arising from full-duplex (FD) operation, the
underlying max-min problem is cast as an optimization problem which is
non-convex. To circumvent this issue, semidefinite relaxation technique is
employed, leading to upper and lower bound solutions for the optimization
problem. Numerical results verify that the upper and lower bound solutions
closely follow each other, showing that the proposed approach results in a
close-to-optimal solution. In addition, the impact of residual
self-interference upon the overall performance of the network in terms of the
minimum rate is illustrated by numerical results, and for low residual
self-interference scenarios the superiority of the proposed method compared to
an analogous half-duplex (HD) counterpart is shown
Joint Source and Relay Precoding Designs for MIMO Two-Way Relaying Based on MSE Criterion
Properly designed precoders can significantly improve the spectral efficiency
of multiple-input multiple-output (MIMO) relay systems. In this paper, we
investigate joint source and relay precoding design based on the
mean-square-error (MSE) criterion in MIMO two-way relay systems, where two
multi-antenna source nodes exchange information via a multi-antenna
amplify-and-forward relay node. This problem is non-convex and its optimal
solution remains unsolved. Aiming to find an efficient way to solve the
problem, we first decouple the primal problem into three tractable
sub-problems, and then propose an iterative precoding design algorithm based on
alternating optimization. The solution to each sub-problem is optimal and
unique, thus the convergence of the iterative algorithm is guaranteed.
Secondly, we propose a structured precoding design to lower the computational
complexity. The proposed precoding structure is able to parallelize the
channels in the multiple access (MAC) phase and broadcast (BC) phase. It thus
reduces the precoding design to a simple power allocation problem. Lastly, for
the special case where only a single data stream is transmitted from each
source node, we present a source-antenna-selection (SAS) based precoding design
algorithm. This algorithm selects only one antenna for transmission from each
source and thus requires lower signalling overhead. Comprehensive simulation is
conducted to evaluate the effectiveness of all the proposed precoding designs.Comment: 32 pages, 10 figure
Physical Layer Service Integration in 5G: Potentials and Challenges
High transmission rate and secure communication have been identified as the
key targets that need to be effectively addressed by fifth generation (5G)
wireless systems. In this context, the concept of physical-layer security
becomes attractive, as it can establish perfect security using only the
characteristics of wireless medium. Nonetheless, to further increase the
spectral efficiency, an emerging concept, termed physical-layer service
integration (PHY-SI), has been recognized as an effective means. Its basic idea
is to combine multiple coexisting services, i.e., multicast/broadcast service
and confidential service, into one integral service for one-time transmission
at the transmitter side. This article first provides a tutorial on typical
PHY-SI models. Furthermore, we propose some state-of-the-art solutions to
improve the overall performance of PHY-SI in certain important communication
scenarios. In particular, we highlight the extension of several concepts
borrowed from conventional single-service communications, such as artificial
noise (AN), eigenmode transmission etc., to the scenario of PHY-SI. These
techniques are shown to be effective in the design of reliable and robust
PHY-SI schemes. Finally, several potential research directions are identified
for future work.Comment: 12 pages, 7 figure
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