2,249 research outputs found
Recovering Multiplexing Loss Through Successive Relaying Using Repetition Coding
In this paper, a transmission protocol is studied for a two relay wireless
network in which simple repetition coding is applied at the relays.
Information-theoretic achievable rates for this transmission scheme are given,
and a space-time V-BLAST signalling and detection method that can approach them
is developed. It is shown through the diversity multiplexing tradeoff analysis
that this transmission scheme can recover the multiplexing loss of the
half-duplex relay network, while retaining some diversity gain. This scheme is
also compared with conventional transmission protocols that exploit only the
diversity of the network at the cost of a multiplexing loss. It is shown that
the new transmission protocol offers significant performance advantages over
conventional protocols, especially when the interference between the two relays
is sufficiently strong.Comment: To appear in the IEEE Transactions on Wireless Communication
Selective Combining for Hybrid Cooperative Networks
In this study, we consider the selective combining in hybrid cooperative
networks (SCHCNs scheme) with one source node, one destination node and
relay nodes. In the SCHCN scheme, each relay first adaptively chooses between
amplify-and-forward protocol and decode-and-forward protocol on a per frame
basis by examining the error-detecting code result, and () relays will be selected to forward their received signals to the
destination. We first develop a signal-to-noise ratio (SNR) threshold-based
frame error rate (FER) approximation model. Then, the theoretical FER
expressions for the SCHCN scheme are derived by utilizing the proposed SNR
threshold-based FER approximation model. The analytical FER expressions are
validated through simulation results.Comment: 27 pages, 8 figures, IET Communications, 201
The Impact of Channel Feedback on Opportunistic Relay Selection for Hybrid-ARQ in Wireless Networks
This paper presents a decentralized relay selection protocol for a dense
wireless network and describes channel feedback strategies that improve its
performance. The proposed selection protocol supports hybrid
automatic-repeat-request transmission where relays forward parity information
to the destination in the event of a decoding error. Channel feedback is
employed for refining the relay selection process and for selecting an
appropriate transmission mode in a proposed adaptive modulation transmission
framework. An approximation of the throughput of the proposed adaptive
modulation strategy is presented, and the dependence of the throughput on
system parameters such as the relay contention probability and the adaptive
modulation switching point is illustrated via maximization of this
approximation. Simulations show that the throughput of the proposed selection
strategy is comparable to that yielded by a centralized selection approach that
relies on geographic information.Comment: 30 pages, 9 figures, submitted to the IEEE Transactions on Vehicular
Technology, revised March 200
Optimal Relay Selection for Physical-Layer Security in Cooperative Wireless Networks
In this paper, we explore the physical-layer security in cooperative wireless
networks with multiple relays where both amplify-and-forward (AF) and
decode-and-forward (DF) protocols are considered. We propose the AF and DF
based optimal relay selection (i.e., AFbORS and DFbORS) schemes to improve the
wireless security against eavesdropping attack. For the purpose of comparison,
we examine the traditional AFbORS and DFbORS schemes, denoted by T-AFbORS and
TDFbORS, respectively. We also investigate a so-called multiple relay combining
(MRC) framework and present the traditional AF and DF based MRC schemes, called
T-AFbMRC and TDFbMRC, where multiple relays participate in forwarding the
source signal to destination which then combines its received signals from the
multiple relays. We derive closed-form intercept probability expressions of the
proposed AFbORS and DFbORS (i.e., P-AFbORS and P-DFbORS) as well as the
T-AFbORS, TDFbORS, T-AFbMRC and T-DFbMRC schemes in the presence of
eavesdropping attack. We further conduct an asymptotic intercept probability
analysis to evaluate the diversity order performance of relay selection schemes
and show that no matter which relaying protocol is considered (i.e., AF and
DF), the traditional and proposed optimal relay selection approaches both
achieve the diversity order M where M represents the number of relays. In
addition, numerical results show that for both AF and DF protocols, the
intercept probability performance of proposed optimal relay selection is
strictly better than that of the traditional relay selection and multiple relay
combining methods.Comment: 13 page
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