197 research outputs found
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
Efficient systematic turbo polar decoding based on optimized scaling factor and early termination mechanism
In this paper, an efficient early termination (ET) mechanism for systematic turbo-polar code (STPC) based on optimal estimation of scaling factor (SF) is proposed. The gradient of the regression line which best fits the distance between a priori and extrinsic information is used to estimate the SF. The multiplication of the extrinsic information by the proposed SF presents effectiveness in resolving the correlation issue between intrinsic and extrinsic reliability information traded between the two typical parallel concatenated soft-cancellation (SCAN) decoders. It is shown that the SF has improved the conventional STPC by about 0.3 dB with an interleaver length of 64 bits, and about 1 dB over the systematic polar code (SPC) at a bit error rate (BER) of . A new scheme is proposed as a stopping criterion, which is mainly based on the estimated value of SF at the second component decoder and the decoded frozen bits for each decoding iteration. It is shown that the proposed ET results in halving the average number of iterations (ANI) without adding considerable complexity. Moreover, the modified codes present comparable results in terms of BER to the codes that utilize fix number of iterations
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