1,905 research outputs found
TTCM-aided rate-adaptive distributed source coding for Rayleigh fading channels
Adaptive turbo-trellis-coded modulation (TTCM)-aided asymmetric distributed source coding (DSC) is proposed, where two correlated sources are transmitted to a destination node. The first source sequence is TTCM encoded and is further compressed before it is transmitted through a Rayleigh fading channel, whereas the second source signal is assumed to be perfectly decoded and, hence, to be flawlessly shown at the destination for exploitation as side information for improving the decoding performance of the first source. The proposed scheme is capable of reliable communications within 0.80 dB of the Slepian-Wolf/Shannon (SW/S) theoretical limit at a bit error rate (BER) of 10-5. Furthermore, its encoder is capable of accommodating time-variant short-term correlation between the two sources
Space-Time Signal Design for Multilevel Polar Coding in Slow Fading Broadcast Channels
Slow fading broadcast channels can model a wide range of applications in
wireless networks. Due to delay requirements and the unavailability of the
channel state information at the transmitter (CSIT), these channels for many
applications are non-ergodic. The appropriate measure for designing signals in
non-ergodic channels is the outage probability. In this paper, we provide a
method to optimize STBCs based on the outage probability at moderate SNRs.
Multilevel polar coded-modulation is a new class of coded-modulation techniques
that benefits from low complexity decoders and simple rate matching. In this
paper, we derive the outage optimality condition for multistage decoding and
propose a rule for determining component code rates. We also derive an upper
bound on the outage probability of STBCs for designing the
set-partitioning-based labelling. Finally, due to the optimality of the
outage-minimized STBCs for long codes, we introduce a novel method for the
joint optimization of short-to-moderate length polar codes and STBCs
Polar Coding for Fading Channels
A polar coding scheme for fading channels is proposed in this paper. More
specifically, the focus is Gaussian fading channel with a BPSK modulation
technique, where the equivalent channel could be modeled as a binary symmetric
channel with varying cross-over probabilities. To deal with variable channel
states, a coding scheme of hierarchically utilizing polar codes is proposed. In
particular, by observing the polarization of different binary symmetric
channels over different fading blocks, each channel use corresponding to a
different polarization is modeled as a binary erasure channel such that polar
codes could be adopted to encode over blocks. It is shown that the proposed
coding scheme, without instantaneous channel state information at the
transmitter, achieves the capacity of the corresponding fading binary symmetric
channel, which is constructed from the underlying fading AWGN channel through
the modulation scheme.Comment: 6 pages, 4 figures, conferenc
Self-concatenated code design and its application in power-efficient cooperative communications
In this tutorial, we have focused on the design of binary self-concatenated coding schemes with the help of EXtrinsic Information Transfer (EXIT) charts and Union bound analysis. The design methodology of future iteratively decoded self-concatenated aided cooperative communication schemes is presented. In doing so, we will identify the most important milestones in the area of channel coding, concatenated coding schemes and cooperative communication systems till date and suggest future research directions
Performance Analysis of Adaptive Physical Layer Network Coding for Wireless Two-way Relaying
The analysis of modulation schemes for the physical layer network-coded two
way relaying scenario is presented which employs two phases: Multiple access
(MA) phase and Broadcast (BC) phase. It was shown by Koike-Akino et. al. that
adaptively changing the network coding map used at the relay according to the
channel conditions greatly reduces the impact of multiple access interference
which occurs at the relay during the MA phase. Depending on the signal set used
at the end nodes, deep fades occur for a finite number of channel fade states
referred as the singular fade states. The singular fade states fall into the
following two classes: The ones which are caused due to channel outage and
whose harmful effect cannot be mitigated by adaptive network coding are
referred as the \textit{non-removable singular fade states}. The ones which
occur due to the choice of the signal set and whose harmful effects can be
removed by a proper choice of the adaptive network coding map are referred as
the \textit{removable} singular fade states. In this paper, we derive an upper
bound on the average end-to-end Symbol Error Rate (SER), with and without
adaptive network coding at the relay, for a Rician fading scenario. It is shown
that without adaptive network coding, at high Signal to Noise Ratio (SNR), the
contribution to the end-to-end SER comes from the following error events which
fall as : the error events associated with the removable
singular fade states, the error events associated with the non-removable
singular fade states and the error event during the BC phase. In contrast, for
the adaptive network coding scheme, the error events associated with the
removable singular fade states contributing to the average end-to-end SER fall
as and as a result the adaptive network coding scheme
provides a coding gain over the case when adaptive network coding is not used.Comment: 10 pages, 5 figure
A system level simulation study of WiMAX
Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2010.Thesis (Master's) -- Bilkent University, 2010.Includes bibliographical references leaves 56-58.In this thesis, we implement a WiMAX system level simulator compliant with the
evaluation methodology document published by the IEEE 802.16m Task Group.
We study the PHY abstraction of polar codes and integrate polar codes into
the simulator. We compare the system level performances of polar code and
convolutional turbo code (CTC) and observe that CTC outperforms polar code.
On the simulator, we study the downlink (DL) performance of WiMAX under
various configurations such as scheduling methods, subchannelization methods,
and frequency reuse models. We study there types of scheduling methods, namely
round robin (RR) scheduling, proportional fair (PF) scheduling, and maximum
sum rate (MSR) scheduling. We observe that MSR scheduling has the best
throughput performance but does not support the users far from the base station.
We study three frequency reuse models, namely 1×3×1, 1×3×3, and 3×3×1.
We observe that 1 ×3×1 reuse model has the best throughput performance and
maximum spectral efficiency is obtained in 1 × 3 × 3 reuse model. We study two
subchannelization methods, namely PUSC and band AMC. We observe that in
low mobility cases, band AMC outperforms PUSC and in high mobility cases,
PUSC is better than band AMC.Başçiftçi, Yüksel OzanM.S
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