262 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
Cellular Multi-User Two-Way MIMO AF Relaying via Signal Space Alignment: Minimum Weighted SINR Maximization
In this paper, we consider linear MIMO transceiver design for a cellular
two-way amplify-and-forward relaying system consisting of a single
multi-antenna base station, a single multi-antenna relay station, and multiple
multi-antenna mobile stations (MSs). Due to the two-way transmission, the MSs
could suffer from tremendous multi-user interference. We apply an interference
management model exploiting signal space alignment and propose a transceiver
design algorithm, which allows for alleviating the loss in spectral efficiency
due to half-duplex operation and providing flexible performance optimization
accounting for each user's quality of service priorities. Numerical comparisons
to conventional two-way relaying schemes based on bidirectional channel
inversion and spatial division multiple access-only processing show that the
proposed scheme achieves superior error rate and average data rate performance
Dispensing with channel estimation: differentially modulated cooperative wireless communications
As a benefit of bypassing the potentially excessive complexity and yet inaccurate channel estimation, differentially encoded modulation in conjunction with low-complexity noncoherent detection constitutes a viable candidate for user-cooperative systems, where estimating all the links by the relays is unrealistic. In order to stimulate further research on differentially modulated cooperative systems, a number of fundamental challenges encountered in their practical implementations are addressed, including the time-variant-channel-induced performance erosion, flexible cooperative protocol designs, resource allocation as well as its high-spectral-efficiency transceiver design. Our investigations demonstrate the quantitative benefits of cooperative wireless networks both from a pure capacity perspective as well as from a practical system design perspective
On Capacity of Active Relaying in Magnetic Induction based Wireless Underground Sensor Networks
Wireless underground sensor networks (WUSNs) present a variety of new
research challenges. Magnetic induction (MI) based transmission has been
proposed to overcome the very harsh propagation conditions in underground
communications in recent years. In this approach, induction coils are utilized
as antennas in the sensor nodes. This solution achieves longer transmission
ranges compared to the traditional electromagnetic (EM) waves based approach.
Furthermore, a passive relaying technique has been proposed in the literature
where additional resonant circuits are deployed between the nodes. However,
this solution is shown to provide only a limited performance improvement under
practical system design contraints. In this work, the potential of an active
relay device is investigated which may improve the performance of the system by
combining the benefits of the traditional wireless relaying and the MI based
signal transmission.Comment: This paper has been accepted for presentation at IEEE ICC 2015. It
has 6 pages, 5 figures (4 colored), and 17 reference
Non-coherent successive relaying and cooperation: principles, designs, and applications
Cooperative communication is capable of forming a virtual antenna array for each node (user) in a network by allowing the nodes (users) to relay the messages of others to the destination. Such a relay aided network may be viewed as a distributed multiple-input multiple-output (MIMO) system relying on the spatially distributed single antennas of the cooperating mobiles, which avoids the correlation of the antenna elements routinely encountered in conventional MIMO systems and hence attains the maximum achievable diversity gain. Therefore, the family of cooperative communication techniques may be regarded as a potential solution for future wireless networks. However, constrained by the half-duplex transmit/receive mode of most practical transceivers, the cooperative networks may impose a severe 50% throughput loss. As a remedy, successive relaying can be employed, which is capable of mimicking a full-duplex relay and thereby recovering much of the 50% throughput loss. Furthermore, for the sake of bypassing power-hungry and potentially excessive-complexity channel estimation, noncoherent detection techniques may be employed for multiple-antenna aided systems, because estimating all the associated channels may become unrealistic. Explicitly, the mobile-stations acting as relays cannot be realistically expected to estimate the source-to-relay channels. In order to motivate further research on noncoherent successive relaying aided systems, a comprehensive review of its basic concepts, fundamental principles, practical transceiver designs and open challenges is provide
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