1,940 research outputs found
Study of Switched Max-Link Relay Selection for Cooperative Multiple-Antenna Systems
In this work, we present a switched relaying framework for multiple-input
multiple-output (MIMO) relay systems where a source node may transmit directly
to a destination node or aided by relays. We also investigate relay selection
techniques for the proposed switched relaying framework, whose relays are
equipped with buffers. In particular, we develop a novel relay selection
protocol based on switching and the selection of the best link, denoted as
Switched Max-Link. We then propose the Maximum Minimum Distance (MMD) relay
selection criterion for MIMO systems, which is based on the optimal Maximum
Likelihood (ML) principle and can provide significant performance gains over
other criteria, along with algorithms that are incorporated into the proposed
Switched Max-Link protocol. An analysis of the proposed Switched Max-Link
protocol and the MMD relay selection criterion in terms of computational cost,
pairwise error probability, sum-rate and average delay is carried out.
Simulations show that Switched Max-Link using the MMD criterion outperforms
previous works in terms of sum-rate, pairwise error probability, average delay
and bit error rate.Comment: 15 pages, 13 figure
Study of Max-Link Relay Selection with Buffers for Multi-Way Cooperative Multi-Antenna Systems
In this paper, we present a relay-selection strategy for multi-way
cooperative multi-antenna systems that are aided by a central processor node,
where a cluster formed by two users is selected to simultaneously transmit to
each other with the help of relays. In particular, we present a novel multi-way
relay selection strategy based on the selection of the best link, exploiting
the use of buffers and physical-layer network coding, that is called Multi-Way
Buffer-Aided Max-Link (MW-Max-Link). We compare the proposed MW-Max-Link to
existing techniques in terms of bit error rate, pairwise error probability, sum
rate and computational complexity. Simulations are then employed to evaluate
the performance of the proposed and existing techniques.Comment: 5 pages, 3 figure
A Buffer-aided Successive Opportunistic Relay Selection Scheme with Power Adaptation and Inter-Relay Interference Cancellation for Cooperative Diversity Systems
In this paper we consider a simple cooperative network consisting of a
source, a destination and a cluster of decode-and-forward half-duplex relays.
At each time-slot, the source and (possibly) one of the relays transmit a
packet to another relay and the destination, respectively, resulting in
inter-relay interference (IRI). In this work, with the aid of buffers at the
relays, we mitigate the detrimental effect of IRI through interference
cancellation. More specifically, we propose the min-power scheme that minimizes
the total energy expenditure per time slot under an IRI cancellation scheme.
Apart from minimizing the energy expenditure, the min-power selection scheme,
also provides better throughput and lower outage probability than existing
works in the literature. It is the first time that interference cancellation is
combined with buffer-aided relays and power adaptation to mitigate the IRI and
minimize the energy expenditure. The new relay selection policy is analyzed in
terms of outage probability and diversity, by modeling the evolution of the
relay buffers as a Markov Chain (MC). We construct the state transition matrix
of the MC, and hence obtain the steady state with which we can characterize the
outage probability. The proposed scheme outperforms relevant state-of-the-art
relay selection schemes in terms of throughput, diversity and energy
efficiency, as demonstrated via examples.Comment: Preliminary results of this article have been presented in the IEEE
International Symposium on Personal Indoor and Mobile Radio Communications,
8-11 September, 2013, London, United Kingdo
Relay-Pair Selection in Buffer-Aided Successive Opportunistic Relaying using a Multi-Antenna Source
We study a cooperative network with a buffer-aided multi-antenna source,
multiple half-duplex (HD) buffer-aided relays and a single destination. Such a
setup could represent a cellular downlink scenario, in which the source can be
a more powerful wireless device with a buffer and multiple antennas, while a
set of intermediate less powerful devices are used as relays to reach the
destination. The main target is to recover the multiplexing loss of the network
by having the source and a relay to simultaneously transmit their information
to another relay and the destination, respectively. Successive transmissions in
such a cooperative network, however, cause inter-relay interference (IRI).
First, by assuming global channel state information (CSI), we show that the
detrimental effect of IRI can be alleviated by precoding at the source,
mitigating or even fully cancelling the interference. A cooperative relaying
policy is proposed that employs a joint precoding design and relay-pair
selection. Note that both fixed rate and adaptive rate transmissions can be
considered. For the case when channel state information is only available at
the receiver side (CSIR), we propose a relay selection policy that employs a
phase alignment technique to reduce the IRI. The performance of the two
proposed relay pair selection policies are evaluated and compared with other
state-of-the-art relaying schemes in terms of outage and throughput. The
results show that the use of a powerful source can provide considerable
performance improvements.Comment: 32 pages, 7 figures, Ad Hoc Network
Buffer-Aided Relay Selection Algorithms for Physical-Layer Security in Wireless Networks
In this work, we consider the use of buffer-aided relays, linear precoding
techniques and multiple antennas for physical-layer security in wireless
networks. We develop relay selection algorithms to improve the secrecy-rate
performance of cooperative multi-user multiple-antenna wireless networks. In
particular, we propose a novel finite buffer-aided relay selection algorithm
that employs the maximum likelihood (ML) criterion to select sets of relays
which fully exploit the flexibility offered by relay nodes equipped with
buffers. Numerical results show the benefits of the proposed techniques as
compared to prior art.Comment: 5 pages, 3 figures in WSA 201
Study of Switched Max-Link Buffer-Aided Relay Selection for Cooperative MIMO Systems
In this paper, we investigate relay selection for cooperative
multiple-antenna systems that are equipped with buffers, which increase the
reliability of wireless links. In particular, we present a novel relay
selection technique based on switching and the Max-Link protocol that is named
Switched Max-Link. We also introduce a novel relay selection criterion based on
the maximum likelihood (ML) principle denoted maximum minimum distance that is
incorporated into. Simulations are then employed to evaluate the performance of
the proposed and existing techniques.Comment: 8 pages, 3 figures. arXiv admin note: text overlap with
arXiv:1707.0095
Alternate Distributed Beamforming for Buffer-Aided Multi-Antenna Relay Systems
In this paper, link selection is investigated in half-duplex (HD) dual-hop
cooperative systems with multiple antennas at the relays. Alternate distributed
beamforming (ADB) scheme is revisited for buffer-aided multi-antenna relay
systems, in which the relays are divided into two groups, with one group
receiving the same information broadcast from the source and the other group
transmitting the common messages to the destination via distributed beamforming
in each time slot. It is worth noting that the relays used for reception and
transmission are determined without the need of instantaneous channel state
information (CSI). Theoretical analysis of the achievable throughput of the
proposed scheme in Rayleigh fading is provided and the approximate closed-form
expressions are derived. Simulation results are given to verify the theoretical
analysis. Through numerical results, it is shown that compared with existing
link selection policies, the fixed scheduling ADB scheme achieves a significant
improvement in achievable throughput. It is also shown that for the ADB scheme,
the throughput performance of increasing the number of antennas equipped at
each relay is better than that of increasing the number of relays equipped with
a single antenna when the total number of antennas at the relays is fixed.Comment: 8 pages, 7 figures. arXiv admin note: substantial text overlap with
arXiv:1910.0395
Achievable Rates for the Fading Half-Duplex Single Relay Selection Network Using Buffer-Aided Relaying
In the half-duplex single relay selection network, comprised of a source,
half-duplex relays, and a destination, only one relay is active at any given
time, i.e., only one relay receives or transmits, and the other relays are
inactive, i.e., they do not receive nor transmit. The capacity of this network,
when all links are affected by independent slow time-continuous fading and
additive white Gaussian noise (AWGN), is still unknown, and only achievable
average rates have been reported in the literature so far. In this paper, we
present new achievable average rates for this network which are larger than the
best known average rates. These new average rates are achieved with a
buffer-aided relaying protocol. Since the developed buffer-aided protocol
introduces unbounded delay, we also devise a buffer-aided protocol which limits
the delay at the expense of a decrease in rate. Moreover, we discuss the
practical implementation of the proposed buffer-aided relaying protocols and
show that they do not require more resources for channel state information
acquisition than the existing relay selection protocols.Comment: Published in IEEE Transactions on Wireless Communication
Mimicking Full-Duplex Secure Communications for Buffer-Aided Multi-Relay Systems
This paper considers secure communication in buffer-aided cooperative
wireless networks in the presence of one eavesdropper, which can intercept the
data transmission from both the source and relay nodes. A new max-ratio
relaying protocol is proposed, in which different relays are chosen for
reception and transmission according to the ratio of the legitimate channels to
the eavesdropper channels, so that the relay selected for reception and the
relay selected for transmission can receive and transmit at the same time. It
is worth noting that the relay employs a randomize-and-forward (RF) strategy
such that the eavesdropper can only decode the signals received in the two hops
independently. Theoretical analysis of the secrecy throughput of the proposed
scheme is provided and the approximate closed-form expressions are derived,
which are verified by simulations. Through numerical results, it is shown that
the proposed scheme achieves a significant improvement in secrecy throughput
compared with existing relay selection policies.Comment: 8 pages, 4 figure
Study of Opportunistic Cooperation Techniques using Jamming and Relays for Physical-Layer Security in Buffer-aided Relay Networks
In this paper, we investigate opportunistic relay and jammer cooperation
schemes in multiple-input multiple-output (MIMO) buffer-aided relay networks.
The network consists of one source, an arbitrary number of relay nodes,
legitimate users and eavesdroppers, with the constraints of physical layer
security. We propose an algorithm to select a set of relay nodes to enhance the
legitimate users' transmission and another set of relay nodes to perform
jamming of the eavesdroppers. With Inter-Relay interference (IRI) taken into
account, interference cancellation can be implemented to assist the
transmission of the legitimate users. Secondly, IRI can also be used to further
increase the level of harm of the jamming signal to the eavesdroppers. By
exploiting the fact that the jamming signal can be stored at the relay nodes,
we also propose a hybrid algorithm to set a signal-to-interference and noise
ratio (SINR) threshold at the node to determine the type of signal stored at
the relay node. With this separation, the signals with high SINR are delivered
to the users as conventional relay systems and the low SINR performance signals
are stored as potential jamming signals. Simulation results show that the
proposed techniques obtain a significant improvement in secrecy rate over
previously reported algorithms.Comment: 8 pages, 3 figure
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