Error Control Coding

Error-control coding techniques are of paramount importance to increase the reliability of wireless communications links. In 5G systems, the requirements of reduced energy consumption, quality of service, high data rates and low latency pose challenges for the design of space-time, network and channel codes and the development of decoding algorithms. 

 

 

In our research, the design of channel codes focuses on short block lengths in order to reduce the latency. Turbo and low-density parity-check (LDPC) codes are investigated for 5G wireless systems and applications to cellular and sensor networks. The design of turbo techniques can be improved by careful adjustment of the interleaving structures as well as the exploitation of prior knowledge about channel fading. LDPC code design can be improved by optimizing the graph connections and enhancing its connectivity. Current work on decoding techniques for Turbo and LDPC codes focuses on the improvement of performance through scheduling and reweighting techniques along with the development algorithmic solutions with a focus on high performance, low-complexity implementation, low latency. Key problems in the design of channel codes and the development of decoding algorithms for 5G networks include the limitation of existing designs for short blocks which are performance limited, hardware impairments, limitations imposed by cycles and deficiencies in the exchange of log-likelihood ratios. In our 5G lab, we look at innovative solutions to the problems encountered in the design of precoders, namely:

o   LDPC and Turbo code design for short block lengths

o   High-performance  decoding algorithms

o   Low-complexity and reduced-latency implementations

 

Work on space-time coding and physical-layer network coding techniques has recently focused on the design of space-time codes for sensor networks and device-to-device communications. Specifically, we are currently investigating distributed space-time coding approaches with feedback channels based on optimization techniques.  We are also looking at power allocation strategies, delay-tolerant techniques and physical-layer network coding concepts. Key topics in the design of space-time coding and physical-layer networking coding for 5G networks include the limitation of existing algorithms to imperfect channel state information, relays equipped with buffers, resource allocation across different devices and applications to cellular networks. In our 5G lab, we look at innovative solutions and the following topics:

o   Low-complexity distributed space-time coding algorithms

o   Buffer-aided relay concepts

o   Resource allocation techniques

o   Combined distributed space-time coding and network coding strategies

 

Selected Publications:

A. G. D. Uchoa, C. T. Healy and R. C. de Lamare, ``Iterative Detection and Decoding Algorithms For MIMO Systems in Block-Fading Channels using LDPC Codes”, IEEE Transactions on Vehicular Technology, 2015. pdf codes

A. G. D. Uchoa, C. T. Healy and R. C. de Lamare , ``Structured Root-Check LDPC Codes and PEG-Based Techniques for Block-Fading Channels”, EURASIP Journal on Wireless Communications and Networking, 2015. pdf

 J. Liu and R. C. de Lamare, “Low-Latency Reweighted Belief Propagation Decoding for LDPC Codes”, IEEE Communications Letters, 2012. pdf

C. T. Healy and R. C. de Lamare, “Decoder-Optimised Progressive Edge Growth Algorithms for the Design of LDPC Codes with Low Error Floors”,  IEEE Communications Letters, 2012.  pdf

A. G. D. Uchoa, C. T. Healy, R. C. de Lamare and R. D. Souza, “Design of LDPC Codes Based on Progressive Edge Growth Techniques For Block Fading Channels”, IEEE Communications Letters, 2011. pdf

T. Peng, R. C. de Lamare and A. Schmeink, ``Adaptive Distributed Space-Time Coding Based on Adjustable Code Matrices for Cooperative MIMO Relaying Systems”, IEEE Transactions on Communications, 2013. pdf

P. Li and R. C. de Lamare, "Distributed Iterative Detection with Reduced Message Passing for Networked MIMO Cellular Systems", IEEE Transactions on Vehicular Technology, 2014. pdf

R. C. de Lamare, "Adaptive and Iterative Multi-Branch MMSE Decision Feedback Detection Algorithms for Multi-Antenna Systems", IEEE Transactions on Wireless Communications, October 2013. pdf

P. Li, R. C. de Lamare and R. Fa, “Multiple Feedback Successive Interference Cancellation Detection for Multiuser MIMO Systems”, IEEE Transactions on Wireless Communications, 2011. pdf

 

Matlab Codes and Tools:

Precoding algorithms – codes

Detection algorithms - codes

LDPC-coded detection algorithms - codes

 

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