Paper Title: Improving Quality of Service for 3D NAND SSDs Using LDPC Correction

Paper Abstract: TLC and QLC 3D NAND technologies require LDPC correction just to withstand a few thousand program/erase cycles. LDPC gives its best correction performance through soft decoding, but that method requires read oversampling, that is, reading the same memory location multiple times. Besides the fact that this approach obviously reduces read bandwidth, it also lowers the Quality of Service (QoS) of SSDs, which is the key parameter in high-value data environments. Even short periods in which SSDs are non-responsive are generally unacceptable in such situations. A new hard decoding re-read strategy can be directly used by the LDPC soft decoder, eliminating the need for NAND reads optimized for soft decoding and thus improving QoS significantly.

Paper Author: Rino Micheloni, Fellow, Microchip Technology

Author Bio: Dr. Rino Micheloni is Vice-President and Fellow at Microsemi Corporation, where he currently runs the Flash Signal Processing Labs, with special focus on NAND Flash, Error Correction Codes, and Machine Learning. Prior to joining Microsemi, he was Fellow at PMC-Sierra, working on NAND Flash characterization, LDPC, and NAND Signal Processing as part of the team developing Flash controllers for PCIe SSDs. Before that, he was with IDT as Lead Flash Technologist, driving the architecture and design of the BCH engine in the world’s first PCIe NVMe SSD controller. Early in his career, he led NAND design teams at STMicroelectronics, Hynix, and Infineon/Qimonda; during this time, he developed the industry’s first MLC NOR device with embedded ECC technology and the industry’s first MLC NAND with embedded BCH. Dr. Micheloni is IEEE Senior Member, he has co-authored more than 70 publications, and he holds 278 patents worldwide (including 133 US patents). He received the STMicroelectronics Exceptional Patent Award in 2003 and 2004, and the Infineon/Qimonda IP Award in 2007. Dr. Micheloni has published the following books with Springer: Inside Solid State Drives – 2nd edition (2018), Solid-State-Drives (SSDs) Modeling (2017), 3D Flash Memories (2016), Inside Solid State Drives (2013), Inside NAND Flash Memories (2010), Error Correction Codes for Non-Volatile Memories (2008), Memories in Wireless Systems (2008), and VLSI-Design of Non-Volatile Memories (2005).