Browsing by Author "Mozammel, Amir"
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Item Open Access A tree pruning technique for decoding complexity reduction of polar codes and PAC codes(Institute of Electrical and Electronics Engineers , 2023-05-18) Moradi, Mohsen; Mozammel, AmirSorting operation is one of the main bottlenecks for the successive-cancellation list (SCL) decoding. This paper introduces an improvement to the SCL decoding for polar and pre-transformed polar codes that reduces the number of sorting operations without visible degradation in the code’s error correction performance. In an SCL decoding with an optimum metric function we show that, on average, the correct branch’s bit-metric value must be equal to the bit-channel capacity, and on the other hand, the average bit-metric value of a wrong branch can be at most zero. This implies that a wrong path’s partial path metric value deviates from the bit-channel capacity’s partial summation. For relatively reliable bit-channels, the bit metric for a wrong branch becomes very large negative number, which enables us to detect and prune such paths. We prove that, for a threshold lower than the bit-channel cutoff rate, the probability of pruning the correct path decreases exponentially by the given threshold. Based on these findings, we presented a pruning technique, and the experimental results demonstrate a substantial decrease in the amount of sorting procedures required for SCL decoding. In the stack algorithm, a similar technique is used to significantly reduce the average number of paths in the stack.Item Open Access Concatenated Reed-Solomon and Polarization-Adjusted Convolutional (PAC) Codes(Institute of Electrical and Electronics Engineers (IEEE), 2022-08-24) Moradi, Mohsen; Mozammel, AmirTwo concatenated coding schemes incorporating algebraic Reed-Solomon (RS) codes and polarization-adjusted convolutional (PAC) codes are proposed. Simulation results show that at a bit error rate of 10−5 , a concatenated scheme using RS and PAC codes has more than 0.25 dB coding gain over the NASA standard concatenation scheme, which uses RS and convolutional codes.Item Open Access Hardware implementation of fano decoder for polarization-adjusted convolutional (PAC) codes(IEEE, 2021-10-26) Mozammel, AmirThis brief proposes a hardware implementation architecture for Fano decoding of polarization-adjusted convolutional (PAC) codes. This architecture uses a novel branch metric unit specific to PAC codes. The proposed decoder is tested on FPGA, and its performance is evaluated on ASIC using TSMC 28 nm 0.72 V library. The decoder can be clocked at 500 MHz and reach an average information throughput of 38 Mb/s at 3.5 dB signal-to-noise ratio for a block length of 128 and a code rate of 1/2.