4 research outputs found
Low-Complexity LSTM-Assisted Bit-Flipping Algorithm for Successive Cancellation List Polar Decoder
Polar codes have attracted much attention in the past decade due to their
capacity-achieving performance. The higher decoding capacity is required for 5G
and beyond 5G (B5G). Although the cyclic redundancy check (CRC)- assisted
successive cancellation list bit-flipping (CA-SCLF) decoders have been
developed to obtain a better performance, the solution to error bit correction
(bit-flipping) problem is still imperfect and hard to design. In this work, we
leverage the expert knowledge in communication systems and adopt deep learning
(DL) technique to obtain the better solution. A low-complexity long short-term
memory network (LSTM)-assisted CA-SCLF decoder is proposed to further improve
the performance of conventional CA-SCLF and avoid complexity and memory
overhead. Our test results show that we can effectively improve the BLER
performance by 0.11dB compared to prior work and reduce the complexity and
memory overhead by over 30% of the network.Comment: 5 pages, 5 figure
DNC-Aided SCL-Flip Decoding of Polar Codes
Successive-cancellation list (SCL) decoding of polar codes has been adopted
for 5G. However, the performance is not very satisfactory with moderate code
length. Heuristic or deep-learning-aided (DL-aided) flip algorithms have been
developed to tackle this problem. The key for successful flip decoding is to
accurately identify error bit positions. In this work, we propose a new flip
algorithm with help of differentiable neural computer (DNC). New state and
action encoding are developed for better DNC training and inference efficiency.
The proposed method consists of two phases: i) a flip DNC (F-DNC) is exploited
to rank most likely flip positions for multi-bit flipping; ii) if decoding
still fails, a flip-validate DNC (FV-DNC) is used to re-select error bit
positions for successive flip decoding trials. Supervised training methods are
designed accordingly for the two DNCs. Simulation results show that proposed
DNC-aided SCL-Flip (DNC-SCLF) decoding demonstrates up to 0.34dB coding gain
improvement or 54.2 reduction in average number of decoding attempts compared
to prior works.Comment: Submitted to Globecom 202
Practical Dynamic SC-Flip Polar Decoders: Algorithm and Implementation
SC-Flip (SCF) is a low-complexity polar code decoding algorithm with improved
performance, and is an alternative to high-complexity (CRC)-aided SC-List
(CA-SCL) decoding. However, the performance improvement of SCF is limited since
it can correct up to only one channel error (). Dynamic SCF (DSCF)
algorithm tackles this problem by tackling multiple errors (),
but it requires logarithmic and exponential computations, which make it
infeasible for practical applications. In this work, we propose simplifications
and approximations to make DSCF practically feasible. First, we reduce the
transcendental computations of DSCF decoding to a constant approximation. Then,
we show how to incorporate special node decoding techniques into DSCF
algorithm, creating the Fast-DSCF decoding. Next, we reduce the search span
within the special nodes to further reduce the computational complexity.
Following, we describe a hardware architecture for the Fast-DSCF decoder, in
which we introduce additional simplifications such as metric normalization and
sorter length reduction. All the simplifications and approximations are shown
to have minimal impact on the error-correction performance, and the reported
Fast-DSCF decoder is the only SCF-based architecture that can correct multiple
errors. The Fast-DSCF decoders synthesized using TSMC nm CMOS technology
can achieve a , and Gbps throughput for , respectively. Compared to the state-of-the-art fast CA-SCL decoders
with equivalent FER performance, the proposed decoders are up to
more area-efficient. Finally, observations at energy dissipation indicate that
the Fast-DSCF is more energy-efficient than its CA-SCL-based counterparts.Comment: Accepted for publication in IEEE TS
Polar Codes and Their Quantum-Domain Counterparts
Arikan's polar codes are capable of achieving the Shannon's capacity at a low
encoding and decoding complexity, while inherently supporting rate adaptation.
By virtue of these attractive features, polar codes have provided fierce
competition to both the turbo as well as the Low Density Parity Check (LDPC)
codes, making its way into the 5G New Radio (NR). Realizing the significance of
polar codes, in this paper we provide a comprehensive survey of polar codes,
highlighting the major milestones achieved in the last decade. Furthermore, we
also provide tutorial insights into the polar encoder, decoders as well as the
code construction methods. We also extend our discussions to quantum polar
codes with an emphasis on the underlying quantum-to-classical isomorphism and
the syndrome-based quantum polar codes.Comment: 35 pages, accepted for publication in IEEE Communications Surveys and
Tutorial