18,902 research outputs found
Hybrid Polar Encoding with Applications in Non-Coherent Channels
In coding theory, an error-correcting code can be encoded either
systematically or non-systematically. In a systematic encode, the input data is
embedded in the encoded output. Conversely, in a non-systematic code, the
output does not contain the input symbols. In this paper, we propose a hybrid
encoding scheme for polar codes, in which some data bits are systematically
encoded while the rest are non-systematically encoded. Based on the proposed
scheme, we design a joint channel estimation and data decoding scheme. We use
the systematic bits in the hybrid encoding scheme as pilots for channel
estimation. To mitigate the code rate loss caused by the pilots and to provide
additional error detecting capability, we propose a dynamic pilot design by
building connections between the systematic bits and non-systematic bits.
Simulation results show that the performance of the proposed scheme approaches
that of the traditional non-systematic polar coding scheme with perfect channel
state information (CSI) with the increase of SNR.Comment: 12 pages, 5 figure
A Novel Interleaving Scheme for Polar Codes
It's known that the bit errors of polar codes with successive cancellation
(SC) decoding are coupled. We call the coupled information bits the correlated
bits. In this paper, concatenation schemes are studied for polar codes (as
inner codes) and LDPC codes (as outer codes). In a conventional concatenation
scheme, to achieve a better BER performance, one can divide all bits in a
LDPC block into polar blocks to completely de-correlate the possible
coupled errors. In this paper, we propose a novel interleaving scheme between a
LDPC code and a polar code which breaks the correlation of the errors among the
correlated bits. This interleaving scheme still keeps the simple SC decoding of
polar codes while achieves a comparable BER performance at a much smaller delay
compared with a -block delay scheme
Scalable Successive-Cancellation Hardware Decoder for Polar Codes
Polar codes, discovered by Ar{\i}kan, are the first error-correcting codes
with an explicit construction to provably achieve channel capacity,
asymptotically. However, their error-correction performance at finite lengths
tends to be lower than existing capacity-approaching schemes. Using the
successive-cancellation algorithm, polar decoders can be designed for very long
codes, with low hardware complexity, leveraging the regular structure of such
codes. We present an architecture and an implementation of a scalable hardware
decoder based on this algorithm. This design is shown to scale to code lengths
of up to N = 2^20 on an Altera Stratix IV FPGA, limited almost exclusively by
the amount of available SRAM
Short Block-length Codes for Ultra-Reliable Low-Latency Communications
This paper reviews the state of the art channel coding techniques for
ultra-reliable low latency communication (URLLC). The stringent requirements of
URLLC services, such as ultra-high reliability and low latency, have made it
the most challenging feature of the fifth generation (5G) mobile systems. The
problem is even more challenging for the services beyond the 5G promise, such
as tele-surgery and factory automation, which require latencies less than 1ms
and failure rate as low as . The very low latency requirements of
URLLC do not allow traditional approaches such as re-transmission to be used to
increase the reliability. On the other hand, to guarantee the delay
requirements, the block length needs to be small, so conventional channel
codes, originally designed and optimised for moderate-to-long block-lengths,
show notable deficiencies for short blocks. This paper provides an overview on
channel coding techniques for short block lengths and compares them in terms of
performance and complexity. Several important research directions are
identified and discussed in more detail with several possible solutions.Comment: Accepted for publication in IEEE Communications Magazin
Flexible and Low-Complexity Encoding and Decoding of Systematic Polar Codes
In this work, we present hardware and software implementations of flexible
polar systematic encoders and decoders. The proposed implementations operate on
polar codes of any length less than a maximum and of any rate. We describe the
low-complexity, highly parallel, and flexible systematic-encoding algorithm
that we use and prove its correctness. Our hardware implementation results show
that the overhead of adding code rate and length flexibility is little, and the
impact on operation latency minor compared to code-specific versions. Finally,
the flexible software encoder and decoder implementations are also shown to be
able to maintain high throughput and low latency.Comment: Submitted to IEEE Transactions on Communications, 201
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