What is soft and hard-decision decoding?

Table of Contents

Whereas a hard-decision decoder operates on data that take on a fixed set of possible values (typically 0 or 1 in a binary code), the inputs to a soft-decision decoder may take on a whole range of values in-between.

What is LLR in communication?

Copy Command Copy Code. This example shows the BER performance improvement for QPSK modulation when using log-likelihood ratio (LLR) instead of hard-decision demodulation in a convolutionally coded communication link.

What is LLR in 5G?

Low-density parity-check (LDPC) codes are capacity approaching codes and are adopted for 5G NR [1]. LDPC codes are. decoded iteratively using the message-passing algorithm. The input of the LDPC decoder is usually the log likelihood ratios. (LLRs).

How does Viterbi decoder work?

The Viterbi decoder examines an entire received sequence of a given length. The decoder computes a metric for each path and makes a decision based on this metric. All paths are followed until two paths converge on one node. Then the path with the higher metric is kept and the one with lower metric is discarded.

What is LTE LLR?

Description. The LTE Symbol Demodulator block demodulates complex data symbols to data bits or log likelihood ratios (LLR) values based on the modulation types supported by LTE standard TS 36.211 [1]. The block provides an architecture suitable for HDL code generation and hardware deployment.

What is channel coding in 5G?

5G introduces a variant of Low Density Parity Check or LDPC channel coding, not used in 3GPP standards in the past. Although LDPC has already been used in some WiFi standards, delivering the extreme performance requirements for 5G across the vast range of possible use cases is a whole new challenge.

What is hard decision decoding?

Hard decision decoding takes a stream of bits or a block of bits from the threshold stage of receiver, and decodes each bit by considering it as definitely 1 or 0. It samples the received pulses and compares their voltages to threshold values.

Which algorithm is used in Viterbi decoder?

A Viterbi decoder uses the Viterbi algorithm for decoding a bitstream that has been encoded using a convolutional code or trellis code. There are other algorithms for decoding a convolutionally encoded stream (for example, the Fano algorithm).