13 research outputs found
Partitioned Successive-Cancellation List Decoding of Polar Codes
Successive-cancellation list (SCL) decoding is an algorithm that provides
very good error-correction performance for polar codes. However, its hardware
implementation requires a large amount of memory, mainly to store intermediate
results. In this paper, a partitioned SCL algorithm is proposed to reduce the
large memory requirements of the conventional SCL algorithm. The decoder tree
is broken into partitions that are decoded separately. We show that with
careful selection of list sizes and number of partitions, the proposed
algorithm can outperform conventional SCL while requiring less memory.Comment: 4 pages, 6 figures, to appear at IEEE ICASSP 201
Belief Propagation Decoding of Polar Codes on Permuted Factor Graphs
We show that the performance of iterative belief propagation (BP) decoding of
polar codes can be enhanced by decoding over different carefully chosen factor
graph realizations. With a genie-aided stopping condition, it can achieve the
successive cancellation list (SCL) decoding performance which has already been
shown to achieve the maximum likelihood (ML) bound provided that the list size
is sufficiently large. The proposed decoder is based on different realizations
of the polar code factor graph with randomly permuted stages during decoding.
Additionally, a different way of visualizing the polar code factor graph is
presented, facilitating the analysis of the underlying factor graph and the
comparison of different graph permutations. In our proposed decoder, a high
rate Cyclic Redundancy Check (CRC) code is concatenated with a polar code and
used as an iteration stopping criterion (i.e., genie) to even outperform the
SCL decoder of the plain polar code (without the CRC-aid). Although our
permuted factor graph-based decoder does not outperform the SCL-CRC decoder, it
achieves, to the best of our knowledge, the best performance of all iterative
polar decoders presented thus far.Comment: in IEEE Wireless Commun. and Networking Conf. (WCNC), April 201
Partitioned List Decoding of Polar Codes: Analysis and Improvement of Finite Length Performance
Polar codes represent one of the major recent breakthroughs in coding theory
and, because of their attractive features, they have been selected for the
incoming 5G standard. As such, a lot of attention has been devoted to the
development of decoding algorithms with good error performance and efficient
hardware implementation. One of the leading candidates in this regard is
represented by successive-cancellation list (SCL) decoding. However, its
hardware implementation requires a large amount of memory. Recently, a
partitioned SCL (PSCL) decoder has been proposed to significantly reduce the
memory consumption. In this paper, we examine the paradigm of PSCL decoding
from both theoretical and practical standpoints: (i) by changing the
construction of the code, we are able to improve the performance at no
additional computational, latency or memory cost, (ii) we present an optimal
scheme to allocate cyclic redundancy checks (CRCs), and (iii) we provide an
upper bound on the list size that allows MAP performance.Comment: 2017 IEEE Global Communications Conference (GLOBECOM
Comparison of Polar Decoders with Existing Low-Density Parity-Check and Turbo Decoders
Polar codes are a recently proposed family of provably capacity-achieving
error-correction codes that received a lot of attention. While their
theoretical properties render them interesting, their practicality compared to
other types of codes has not been thoroughly studied. Towards this end, in this
paper, we perform a comparison of polar decoders against LDPC and Turbo
decoders that are used in existing communications standards. More specifically,
we compare both the error-correction performance and the hardware efficiency of
the corresponding hardware implementations. This comparison enables us to
identify applications where polar codes are superior to existing
error-correction coding solutions as well as to determine the most promising
research direction in terms of the hardware implementation of polar decoders.Comment: Fixes small mistakes from the paper to appear in the proceedings of
IEEE WCNC 2017. Results were presented in the "Polar Coding in Wireless
Communications: Theory and Implementation" Worksho
Reduced Path Successive Cancellation List Decoding for Polar Codes
Polar codes have already been adopted in 5G systems to improve error performance. Successive cancellation list (SCL) decoding is usually used at the decoder and involves lengthy processing. Therefore, different methods have been developed to reduce an SCL decoder’s complexity. In this paper, a reduced path successive cancellation list (RP-SCL) decoder is presented to reduce this complexity, where some decoding paths are pruned. The pruning is achieved by using three different thresholds: two for the path metric and one for the pruning depth in the decoding tree. An optimization procedure is considered to determine the optimum settings for these thresholds. The simulation tests are carried out over models of an additive white Gaussian noise channel and a fading channel by using 5G environments. The results reveal that the proposed RP-SCL decoder provides the complexity reduction in terms of the average number of processed paths at high SNR. Additionally, the computational complexity and the memory requirements decrease
Sublinear Latency for Simplified Successive Cancellation Decoding of Polar Codes
This work analyzes the latency of the simplified successive cancellation
(SSC) decoding scheme for polar codes proposed by Alamdar-Yazdi and
Kschischang. It is shown that, unlike conventional successive cancellation
decoding, where latency is linear in the block length, the latency of SSC
decoding is sublinear. More specifically, the latency of SSC decoding is
, where is the block length and is the scaling
exponent of the channel, which captures the speed of convergence of the rate to
capacity. Numerical results demonstrate the tightness of the bound and show
that most of the latency reduction arises from the parallel decoding of
subcodes of rate or .Comment: 20 pages, 6 figures, presented in part at ISIT 2020 and accepted in
IEEE Transactions on Wireless Communication