886 research outputs found
A Unified Framework for Linear-Programming Based Communication Receivers
It is shown that a large class of communication systems which admit a
sum-product algorithm (SPA) based receiver also admit a corresponding
linear-programming (LP) based receiver. The two receivers have a relationship
defined by the local structure of the underlying graphical model, and are
inhibited by the same phenomenon, which we call 'pseudoconfigurations'. This
concept is a generalization of the concept of 'pseudocodewords' for linear
codes. It is proved that the LP receiver has the 'maximum likelihood
certificate' property, and that the receiver output is the lowest cost
pseudoconfiguration. Equivalence of graph-cover pseudoconfigurations and
linear-programming pseudoconfigurations is also proved. A concept of 'system
pseudodistance' is defined which generalizes the existing concept of
pseudodistance for binary and nonbinary linear codes. It is demonstrated how
the LP design technique may be applied to the problem of joint equalization and
decoding of coded transmissions over a frequency selective channel, and a
simulation-based analysis of the error events of the resulting LP receiver is
also provided. For this particular application, the proposed LP receiver is
shown to be competitive with other receivers, and to be capable of
outperforming turbo equalization in bit and frame error rate performance.Comment: 13 pages, 6 figures. To appear in the IEEE Transactions on
Communication
Codeword-Independent Performance of Nonbinary Linear Codes Under Linear-Programming and Sum-Product Decoding
A coded modulation system is considered in which nonbinary coded symbols are
mapped directly to nonbinary modulation signals. It is proved that if the
modulator-channel combination satisfies a particular symmetry condition, the
codeword error rate performance is independent of the transmitted codeword. It
is shown that this result holds for both linear-programming decoders and
sum-product decoders. In particular, this provides a natural modulation mapping
for nonbinary codes mapped to PSK constellations for transmission over
memoryless channels such as AWGN channels or flat fading channels with AWGN.Comment: 5 pages, Proceedings of the 2008 IEEE International Symposium on
Information Theory, Toronto, ON, Canada, July 6-11, 200
Transmit Antenna Selection for Physical-Layer Network Coding Based on Euclidean Distance
Physical-layer network coding (PNC) is now well-known as a potential
candidate for delay-sensitive and spectrally efficient communication
applications, especially in two-way relay channels (TWRCs). In this paper, we
present the error performance analysis of a multiple-input single-output (MISO)
fixed network coding (FNC) system with two different transmit antenna selection
(TAS) schemes. For the first scheme, where the antenna selection is performed
based on the strongest channel, we derive a tight closed-form upper bound on
the average symbol error rate (SER) with -ary modulation and show that the
system achieves a diversity order of 1 for . Next, we propose a
Euclidean distance (ED) based antenna selection scheme which outperforms the
first scheme in terms of error performance and is shown to achieve a diversity
order lower bounded by the minimum of the number of antennas at the two users.Comment: 15 pages, 4 figures, Globecom 2017 (Wireless Communications
Symposium
Performance Analysis of NOMA-based Cooperative Relaying in {\alpha} - {\mu} Fading Channels
Non-orthogonal multiple access (NOMA) is widely recognized as a potential
multiple access technology for efficient radio spectrum utilization in the
fifth-generation (5G) wireless communications standard. In this paper, we study
the average achievable rate and outage probability of a cooperative relaying
system (CRS) based on NOMA (CRS-NOMA) over wireless links governed by the
- generalized fading model; here and designate the
nonlinearity and clustering parameters, respectively, of each link. The average
achievable rate is represented in closed-form using Meijer's G-function and the
extended generalized bivariate Fox's H-function (EGBFHF), and the outage
probability is represented using the lower incomplete Gamma function. Our
results confirm that the CRS-NOMA outperforms the CRS with conventional
orthogonal multiple access (CRS-OMA) in terms of spectral efficiency at high
transmit signal-to-noise ratio (SNR). It is also evident from our results that
with an increase in the value of the nonlinearity/clustering parameter, the SNR
at which the CRS-NOMA outperforms its OMA based counterpart becomes higher.
Furthermore, the asymptotic analysis of the outage probability reveals the
dependency of the diversity order of each symbol in the CRS-NOMA system on the
and parameters of the fading links.Comment: 16 pages, 7 figures, 1 table, accepted in IEEE International
Conference on Communications (ICC) - 2019, Shangha
Fundamental Limits of Spectrum Sharing for NOMA-based Cooperative Relaying
Non-orthogonal multiple access (NOMA) and spectrum sharing (SS) are two
emerging multiple access technologies for efficient spectrum utilization in the
fifth-generation (5G) wireless communications standard. In this paper, we
present a closed-form analysis of the average achievable sum-rate and outage
probability for a NOMA-based cooperative relaying system (CRS) in an underlay
spectrum sharing scenario. We consider a peak interference constraint, where
the interference inflicted by the secondary (unlicensed) network on the
primary-user (licensed) receiver (PU-Rx) should be less than a predetermined
threshold. We show that the CRS-NOMA outperforms the CRS with conventional
orthogonal multiple access (OMA) for large values of peak interference power at
the PU-Rx.Comment: 3 figures, Accepted for presentation in GLOBECOM-NOMAT5G workshop,
Abu Dhabi, 201
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