Feedback Systems using Non-Binary LDPC Codes

This presentation considers feedback communication systems that use non-binary (NB) low-density parity-check (LDPC) codes with incremental transmissions to achieve over 90% of binary-input additive-white-Gaussian-noise (AWGN) channel capacity with average blocklengths of fewer than 500 transmitted bits. In this talk we consider both variable-length feedback codes with termination (VLFT) and the more practical variable length feedback (VLF) codes without termination that require no assumption of noiseless transmitter confirmation. The size of each incremental transmission for NB- LDPC codes is optimized to maximize throughput in VLFT, two-phase VLF, and VLF-with-CRC settings. The optimization problem uses an approximation based on the inverse-Gaussian p.d.f. of the blocklength required for successful decoding. By using the optimized incremental transmission lengths (with an average blocklength of less than 500 bits), a two-phase VLF system limited to five transmissions achieves greater than 90% of the capacity of binary-input AWGN channel with SNR=2 dB. For the VLF-with-CRC setting and an unlimited number of transmissions, with average blocklengths less than 500 bits, NB-LDPC codes can achieve close to 95% of the capacity, while about 90% of capacity is still achieved when then number of transmissions is limited to five.

Short Bio
Kasra Vakilinia is a Ph.D. candidate in Electrical Engineering Department at the University of California, Los Angeles (UCLA). He is a member of the UCLA Communication Systems Laboratory (CSL) and UCLA Center on Development of Emerging Storage Systems (CoDESS). His research interests include coding theory, information theory, flash memory storage systems, and communications systems. The main part of his research involves finite-blocklength coding and design of LDPC codes for wireless and flash memory systems.