1,422 research outputs found
Outage Probability Analysis of Dual Hop Relay Networks in Presence of Interference
Cooperative relaying improves the performance of wireless networks by forming
a network of multiple independent virtual sources transmitting the same
information as the source node. However, interference induced in the network
reduces the performance of cooperative communications. In this work the
statistical properties, the cumulative distribution function (CDF) and the
probability density function (PDF) for a basic dual hop cooperative relay
network with an arbitrary number of interferers over Rayleigh fading channels
are derived. Two system models are considered: in the first system model, the
interferers are only at the relay node; and in the second system model,
interferers are both at the relay and the destination. This work is further
extended to Nakagami-m faded interfering channels. Simulation results are
presented on outage probability performance to verify the theoretical analysis
Exploring Relay Cooperation for Secure and Reliable Transmission in Two-Hop Wireless Networks
This work considers the problem of secure and reliable information
transmission via relay cooperation in two-hop relay wireless networks without
the information of both eavesdropper channels and locations. While previous
work on this problem mainly studied infinite networks and their asymptotic
behavior and scaling law results, this papers focuses on a more practical
network with finite number of system nodes and explores the corresponding exact
result on the number of eavesdroppers one network can tolerant to ensure
desired secrecy and reliability. We first study the scenario where path-loss is
equal between all pairs of nodes and consider two transmission protocols there,
one adopts an optimal but complex relay selection process with less load
balance capacity while the other adopts a random but simple relay selection
process with good load balance capacity. Theoretical analysis is then provided
to determine the maximum number of eavesdroppers one network can tolerate to
ensure a desired performance in terms of the secrecy outage probability and
transmission outage probability. We further extend our study to the more
general scenario where path-loss between each pair of nodes also depends the
distance between them, for which a new transmission protocol with both
preferable relay selection and good load balance as well as the corresponding
theoretical analysis are presented.Comment: 13 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1211.707
Generalized Secure Transmission Protocol for Flexible Load-Balance Control with Cooperative Relays in Two-Hop Wireless Networks
This work considers secure transmission protocol for flexible load-balance
control in two-hop relay wireless networks without the information of both
eavesdropper channels and locations. The available secure transmission
protocols via relay cooperation in physical layer secrecy framework cannot
provide a flexible load-balance control, which may significantly limit their
application scopes. This paper extends the conventional works and proposes a
general transmission protocol with considering load-balance control, in which
the relay is randomly selected from the first preferable assistant relays
located in the circle area with the radius and the center at the middle
between source and destination (2HR-() for short). This protocol covers
the available works as special cases, like ones with the optimal relay
selection (, ) and with the random relay selection (,
i.e. the number of system nodes) in the case of equal path-loss, ones
with relay selected from relay selection region () in
the case of distance-dependent path-loss. The theoretic analysis is further
provided to determine the maximum number of eavesdroppers one network can
tolerate to ensure a desired performance in terms of the secrecy outage
probability and transmission outage probability. The analysis results also show
the proposed protocol can balance load distributed among the relays by a proper
setting of and under the premise of specified secure and reliable
requirements.Comment: 15 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1212.0287, arXiv:1212.6627, arXiv:1211.707
Dynamic Channel Allocation for Interference Mitigation in Relay-assisted Wireless Body Networks
We focus on interference mitigation and energy conservation within a single
wireless body area network (WBAN). We adopt two-hop communication scheme
supported by the the IEEE 802.15.6 standard (2012). In this paper, we propose a
dynamic channel allocation scheme, namely DCAIM to mitigate node-level
interference amongst the coexisting regions of a WBAN. At the time, the sensors
are in the radius communication of a relay, they form a relay region (RG)
coordinated by that relay using time division multiple access (TDMA). In the
proposed scheme, each RG creates a table consisting of interfering sensors
which it broadcasts to its neighboring sensors. This broadcast allows each pair
of RGs to create an interference set (IS). Thus, the members of IS are assigned
orthogonal sub-channels whereas other sonsors that do not belong to IS can
transmit using the same time slots. Experimental results show that our proposal
mitigates node-level interference and improves node and WBAN energy savings.
These results are then compared to the results of other schemes. As a result,
our scheme outperforms in all cases. Node-level signal to interference and
noise ratio (SINR) improved by 11dB whilst, the energy consumption decreased
significantly. We further present a probabilistic method and analytically show
the outage probability can be effectively reduced to the minimal.Comment: 2nd IEEE International Symposium on Future Information and
Communication Technologies for Ubiquitous HealthCare (Ubi-HealthTech),
Beijing, China, 201
Interference Avoidance Algorithm (IAA) for Multi-hop Wireless Body Area Network Communication
In this paper, we propose a distributed multi-hop interference avoidance
algorithm, namely, IAA to avoid co-channel interference inside a wireless body
area network (WBAN). Our proposal adopts carrier sense multiple access with
collision avoidance (CSMA/CA) between sources and relays and a flexible time
division multiple access (FTDMA) between relays and coordinator. The proposed
scheme enables low interfering nodes to transmit their messages using base
channel. Depending on suitable situations, high interfering nodes double their
contention windows (CW) and probably use switched orthogonal channel.
Simulation results show that proposed scheme has far better minimum SINR (12dB
improvement) and longer energy lifetime than other schemes (power control and
opportunistic relaying). Additionally, we validate our proposal in a
theoretical analysis and also propose a probabilistic approach to prove the
outage probability can be effectively reduced to the minimal.Comment: 17th International Conference on E-health networking, Application &
Services, Boston, USA, 201
An Upper Bound on Multi-hop Transmission Capacity with Dynamic Routing Selection
This paper develops upper bounds on the end-to-end transmission capacity of
multi-hop wireless networks. Potential source-destination paths are dynamically
selected from a pool of randomly located relays, from which a closed-form lower
bound on the outage probability is derived in terms of the expected number of
potential paths. This is in turn used to provide an upper bound on the number
of successful transmissions that can occur per unit area, which is known as the
transmission capacity. The upper bound results from assuming independence among
the potential paths, and can be viewed as the maximum diversity case. A useful
aspect of the upper bound is its simple form for an arbitrary-sized network,
which allows insights into how the number of hops and other network parameters
affect spatial throughput in the non-asymptotic regime. The outage probability
analysis is then extended to account for retransmissions with a maximum number
of allowed attempts. In contrast to prevailing wisdom, we show that
predetermined routing (such as nearest-neighbor) is suboptimal, since more hops
are not useful once the network is interference-limited. Our results also make
clear that randomness in the location of relay sets and dynamically varying
channel states is helpful in obtaining higher aggregate throughput, and that
dynamic route selection should be used to exploit path diversity.Comment: 14 pages, 5 figures, accepted to IEEE Transactions on Information
Theory, 201
Outage Probability for Multi-Hop Full-Duplex Decode and Forward MIMO Relay
In this paper, a multi-hop (MH) decode-and-forward (DF) multiple-input
multiple-output (MIMO) relay network has been studied. To consider a more
realistic scenario, Full-Duplex (FD) operation with Relay Self-Interference
(RSI) is employed.
Assuming that the MIMO channels are subject to Rayleigh fading, a simple and
compact closed-form outage probability expression has been derived. The key
assumption to derive this result is that the mutual information of each channel
could be well approximated by a Gaussian random variable. In order to obtain
the resultant outage probability, a new excellent accurate approximation has
been obtained for the sum of Wishart distributed complex random matrices.
Numerical Monte Carlo simulations have been performed to validate our result.
These simulations have shown that, for low and medium interference regime, FD
mode performs better than Half-Duplex (HD) mode. On the other hand, when RSI
increases, HD mode can outperforms FD mode
Joint Relay and Jammer Selection Improves the Physical Layer Security in the Face of CSI Feedback Delays
We enhance the physical-layer security (PLS) of amplify-and-forward relaying
networks with the aid of joint relay and jammer selection (JRJS), despite the
deliterious effect of channel state information (CSI) feedback delays.
Furthermore, we conceive a new outage-based characterization approach for the
JRJS scheme. The traditional best relay selection (TBRS) is also considered as
a benchmark. We first derive closed-form expressions of both the connection
outage probability (COP) and of the secrecy outage probability (SOP) for both
the TBRS and JRJS schemes. Then, a reliable-and-secure connection probability
(RSCP) is defined and analyzed for characterizing the effect of the correlation
between the COP and SOP introduced by the corporate source-relay link. The
reliability-security ratio (RSR) is introduced for characterizing the
relationship between the reliability and security through the asymptotic
analysis. Moreover, the concept of effective secrecy throughput is defined as
the product of the secrecy rate and of the RSCP for the sake of characterizing
the overall efficiency of the system, as determined by the transmit SNR,
secrecy codeword rate and the power sharing ratio between the relay and jammer.
The impact of the direct source-eavesdropper link and additional performance
comparisons with respect to other related selection schemes are further
included. Our numerical results show that the JRJS scheme outperforms the TBRS
method both in terms of the RSCP as well as in terms of its effective secrecy
throughput, but it is more sensitive to the feedback delays. Increasing the
transmit SNR will not always improve the overall throughput. Moreover, the RSR
results demonstrate that upon reducing the CSI feedback delays, the reliability
improves more substantially than the security degrades, implying an overall
improvement in terms of the security-reliability tradeoff.Comment: 15 pages, IEEE Transactions on Vehicular Technology, Sept. 201
Cognitive MIMO-RF/FSO Cooperative Relay Communication with Mobile Nodes and Imperfect Channel State Information
This work analyzes the performance of an underlay cognitive radio based
decode-and-forward mixed multiple-input multiple-output (MIMO) radio
frequency/free space optical (RF/FSO) cooperative relay system with multiple
mobile secondary and primary user nodes. The effect of imperfect channel state
information (CSI) arising due to channel estimation error is also considered at
the secondary user transmitters (SU-TXs) and relay on the power control and
symbol detection processes respectively. A unique aspect of this work is that
both fixed and proportional interference power constraints are employed to
limit the interference at the primary user receivers (PU-RXs). Analytical
results are derived to characterize the exact and asymptotic outage and bit
error probabilities of the above system under practical conditions of node
mobility and imperfect CSI, together with impairments of the optical channel,
such as path loss, atmospheric turbulence, and pointing errors, for orthogonal
space-time block coded transmission between each SU-TX and relay. Finally,
simulation results are presented to yield various interesting insights into the
system performance such as the benefits of a midamble versus preamble for
channel estimation.Comment: revision submitted to IEEE Transactions on Cognitive Communications
and Networkin
Secure and Reliable Transmission with Cooperative Relays in Two-Hop Wireless Networks
This work considers the secure and reliable information transmission in
two-hop relay wireless networks without the information of both eavesdropper
channels and locations. While the previous work on this problem mainly studied
infinite networks and their asymptotic behavior and scaling law results, this
papers focuses on a more practical network with finite number of system nodes
and explores the corresponding exact results on the number of eavesdroppers the
network can tolerant to ensure a desired secrecy and reliability. For achieving
secure and reliable information transmission in a finite network, two
transmission protocols are considered in this paper, one adopts an optimal but
complex relay selection process with less load balance capacity while the other
adopts a random but simple relay selection process with good load balance
capacity. Theoretical analysis is further provided to determine the exact and
maximum number of independent and also uniformly distributed eavesdroppers one
network can tolerate to satisfy a specified requirement in terms of the maximum
secrecy outage probability and maximum transmission outage probability allowed.Comment: 6 pages, 1 figur
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