667 research outputs found
Cooperative Symbol-Based Signaling for Networks with Multiple Relays
Wireless channels suffer from severe inherent impairments and hence
reliable and high data rate wireless transmission is particularly challenging to
achieve. Fortunately, using multiple antennae improves performance in wireless
transmission by providing space diversity, spatial multiplexing, and power gains.
However, in wireless ad-hoc networks multiple antennae may not be acceptable
due to limitations in size, cost, and hardware complexity. As a result, cooperative
relaying strategies have attracted considerable attention because of their abilities
to take advantage of multi-antenna by using multiple single-antenna relays.
This study is to explore cooperative signaling for different relay networks,
such as multi-hop relay networks formed by multiple single-antenna relays and
multi-stage relay networks formed by multiple relaying stages with each stage
holding several single-antenna relays. The main contribution of this study is the
development of a new relaying scheme for networks using symbol-level
modulation, such as binary phase shift keying (BPSK) and quadrature phase shift
keying (QPSK). We also analyze effects of this newly developed scheme when it
is used with space-time coding in a multi-stage relay network. Simulation results
demonstrate that the new scheme outperforms previously proposed schemes:
amplify-and-forward (AF) scheme and decode-and-forward (DF) scheme
Performance of Joint Channel and Physical Network Coding Based on Alamouti STBC
This work considers the protograph-coded physical network coding (PNC) based
on Alamouti space-time block coding (STBC) over Nakagami-fading two-way relay
channels, in which both the two sources and relay possess two antennas. We
first propose a novel precoding scheme at the two sources so as to implement
the iterative decoder efficiently at the relay. We further address a simplified
updating rule of the log-likelihood-ratio (LLR) in such a decoder. Based on the
simplified LLR-updating rule and Gaussian approximation, we analyze the
theoretical bit-error-rate (BER) of the system, which is shown to be consistent
with the decoding thresholds and simulated results. Moreover, the theoretical
analysis has lower computational complexity than the protograph extrinsic
information transfer (PEXIT) algorithm. Consequently, the analysis not only
provides a simple way to evaluate the error performance but also facilitates
the design of the joint channel-and-PNC (JCNC) in wireless communication
scenarios.Comment: 6 pages, 4 figures, accpete
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