Extended Barrel-Shifter for Versatile QC-LDPC Decoders

Abstract

In this paper, we present a Barrel-Shifter of size n extended by an additional layer that can handle any circular permutation on a vector of size m, m ≤ n, thanks to a specific initial positioning of the data. The construction of the so-called Extended Barrel-Shifter is motivated by the hardware decoder constraint related to the Low-Density Parity-Check (LDPC) code recently adopted for the 5G mobile standard. The proposed algorithm requires 42 % less multiplexers than the best stateof-the-art solution for n = 384 of the 5G LDPC standard. This proposal is also able to process several inputs in parallel without extra hardware cost.

Back-to-Back Butterfly Network, an Adaptive Permutation Network for New Communication Standards

“…For instance, a frame of 384 elements can be processed simultaneously with a frame of 512 − 384 = 128 elements. Table I shows the number of MUXs of our model compared to QSN [8] and EBS [11]. Recalling that QSN cannot perform several frames in parallel and EBS is limited in this context.…”

“…However, the main limitation of this solution is that only one single frame can be processed at a time. The most recent algorithm in this context is the Extended Barrel Shifter (EBS) [11]. The key idea is that the elements of the frame are split up appropriately at the inputs of the barrel shifter such that after performing a circular-shift rotation, each element will be at its desired position at the output or only one shift will still be required to be performed on it.…”

“…For that, an extra stage is added at the output of the barrel shifter to perform the one extra shift when it is necessary. The area consumption of [11] is interestingly low. Nevertheless, [11] can process more than one frame having same length (less than or equal N/2) and they must have same desired circular-shift rotation value.…”

“…The area consumption of [11] is interestingly low. Nevertheless, [11] can process more than one frame having same length (less than or equal N/2) and they must have same desired circular-shift rotation value. Again, [11] has restriction in terms of parallelism.…”

“…Nevertheless, [11] can process more than one frame having same length (less than or equal N/2) and they must have same desired circular-shift rotation value. Again, [11] has restriction in terms of parallelism. The Back-to-Back BN (B 2 BN ) [10] (or similarly Benes network [12]) could be explored.…”