###### Abstract  
Ultra-reliable and low-latency communication (URLLC) in 6G networks is characterized by very high reliability and very low latency to enable mission-critical applications. The ability of a coding scheme to support diverse use cases requires flexibility on the part of the decoder. High reliability and low latency require decoders with improved error rate performance and reduced complexity. This article investigates candidate universal decoding algorithms for 6G communication scenarios. Universal decoders work on a wide range of error-correcting codes, making them scalable for different communication protocols. This article undertakes the comparative analysis and performance evaluation of the code-agnostic decoding schemes, including automorphism ensemble (AED), guessing random additive noise (GRAND), ordered statistics (OSD), belief propagation (BPD), bit flipping (BFD), and their variants. Simulations are carried out in MATLAB (R2024a) for the error rate performance of decoders, and plots are provided for the comparative analysis from the results of inferred data. The key findings in this paper highlight the competitive advantage of universal decoding techniques in comparison to the standardized CA-SCL decoding of polar code. Consequently, this work will help in identifying more efficient decoding algorithms for potential 6G URLLC applications. We aim to provide an insight into the scalability of universal decoding techniques by exploring their key performance metrics and comparing their performances. title=false, backgroundcolor=black!100  
Channel coding is a key physical-layer technique used in digital communication systems for the reliable and efficient transmission of data. The main goal in channel coding theory is to approach channel capacity with minimal computational complexity [5]. Additionally, mission-critical applications have rekindled interest in the effectiveness of short-block-length error-correcting codes due to the need for high-reliability, low-latency communications. As 6G is targeted to support a wide range of applications, it has to cater to diverse data rates, latency, reliability, and massive connectivity requirements. The complex network topology of next-generation wireless communication requires a range of adaptable and state-of-the-art coding schemes. Further, applications utilizing short block lengths require an effective decoder of the coding technique employed. The capacity of the decoder to decode any linear code is known as universality. Different decoding techniques have been developed over the years, often unique to one family of error-correcting codes. Universal soft decoding techniques approximate maximum likelihood (ML) decoders for binary linear codes [6]. Also, for a 6G transmission environment where the channel state varies dynamically, universal decoders work effectively as they can operate without exact knowledge of the channel distribution. Some of the communication protocols where universal decoding techniques find their application are listed here:  
1. Wireless communication--5G NR, Wi-Fi [7], low-power wide-area networks (LP-WANs). Universal decoders enhance the spectral efficiency of the communication system by enabling flexible decoding across different channel conditions. 2. Satellite and space communication--DVB-S2/ DVB-S2X (Digital Video Broadcasting--satellite/second-generation extension.) Universal decoders adapt to unknown channel conditions and burst error-prone environments like cosmic radiation. They also reduce power consumption by working with different coding schemes [8]. 3. Optical fiber communication--GPON (Gigabit Passive Optical Network), OTN (Optical Transport Network). Universal decoding techniques are used for the mitigation of transmission impairments like chromatic and polarization mode dispersion. 4. Cellular IoT--MQTT (message queuing telemetry transport), Industrial IoT (IIoT) protocols (e.g., PROFIBUS, OPC-UA). Universal decoders find their application for data reliability and robustness.