1,848 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
Towards the Optimal Amplify-and-Forward Cooperative Diversity Scheme
In a slow fading channel, how to find a cooperative diversity scheme that
achieves the transmit diversity bound is still an open problem. In fact, all
previously proposed amplify-and-forward (AF) and decode-and-forward (DF)
schemes do not improve with the number of relays in terms of the diversity
multiplexing tradeoff (DMT) for multiplexing gains r higher than 0.5. In this
work, we study the class of slotted amplify-and-forward (SAF) schemes. We first
establish an upper bound on the DMT for any SAF scheme with an arbitrary number
of relays N and number of slots M. Then, we propose a sequential SAF scheme
that can exploit the potential diversity gain in the high multiplexing gain
regime. More precisely, in certain conditions, the sequential SAF scheme
achieves the proposed DMT upper bound which tends to the transmit diversity
bound when M goes to infinity. In particular, for the two-relay case, the
three-slot sequential SAF scheme achieves the proposed upper bound and
outperforms the two-relay non-orthorgonal amplify-and-forward (NAF) scheme of
Azarian et al. for multiplexing gains r < 2/3. Numerical results reveal a
significant gain of our scheme over the previously proposed AF schemes,
especially in high spectral efficiency and large network size regime.Comment: 30 pages, 11 figures, submitted to IEEE trans. IT, revised versio
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