Successive-Cancellation Flip Decoding of Polar Codes Under Fixed Channel-Production Rate

TL;DR

This work proposes a multi-threshold mechanism that restrains the delay of a SCF decoder depending on the state of the buffer to avoid overflow and shows that the proposed mechanism provides better error-correction performance compared to a straightforward codeword-dropping mechanism at the cost of a small increase in complexity.

Abstract

Polar codes are a class of error-correcting codes that provably achieve the capacity of practical channels under the low-complexity successive-cancellation flip (SCF) decoding algorithm. However, the SCF decoding algorithm has a variable execution time with a high (worst-case) decoding latency. This characteristic poses a challenge to the design of receivers that have to operate at fixed data rates. In this work, we propose a multi-threshold mechanism that restrains the delay of a SCF decoder depending on the state of the buffer to avoid overflow. We show that the proposed mechanism provides better error-correction performance compared to a straightforward codeword-dropping mechanism at the cost of a small increase in complexity. In the region of interest for wireless communications, the proposed mechanism can prevent buffer overflow while operating with a fixed channel-production rate that is 1.125 times lower than the rate associated to a single decoding trial.

Figures (5)

• Figure 1: System model containing simplified blocks of channel, buffer, controller and -based decoder. Arrows indicate the data flow between the blocks.
• Figure 2: Average execution time of a decoder with various maximum number of trials $T_{\text{max}}$. Two examples of production coefficients $\upsilon_{\text{pr}}$ are shown as horizontal lines.
• Figure 3: Number of occupied buffer slots over the course of a simulation of the codeword-dropping and the multi-threshold mechanisms for of $2.25$ dB and $\upsilon_{\text{pr}}=1.125$.
• Figure 4: of the codeword-dropping and the multi-threshold mechanisms for the range of and $\upsilon_{\text{pr}}=1.125$.
• Figure 5: of the codeword-dropping and the multi-threshold mechanisms for the range of the $\upsilon_{\text{pr}}$ and of $2.25$ dB.