Laureates of the Japan Prize

The 2020 (36th) Japan Prize

Electronics, Information, Communication
Pioneering contribution to information and coding theory

Citation for the Award

Prof. Robert G. Gallager invented low-density parity-check (LDPC) codes, a coding scheme that can achieve coding efficiency very close to its theoretical limit, known as the Shannon-limit. His invention was crucial in enabling error-free communication over noisy communication channels and led to the realization of today's highly reliable high-speed and large-capacity communication.


Ensuring strong noise resistance in data transmission over wired/wireless communication is essential for achieving high-speed, large-capacity communication with high reliability and high efficiency. A code that can be detected and corrected at the receiving end during a transmission error is called an “error correction code”.


During the 1960s, Prof. Gallager published innovative ideas on the definition of LDPC codes, its efficient decoding schemes, and performance analysis. However, his ideas were not adopted for the next 30 years, partially due to the difficulties of its practical implementations.


During the 1990s, as computer processing capacity rapidly improved, the processing time required for decoding was reduced to the point that the processing of long length codes was no longer problematic. As a result, there was a renewed interest in error correction codes based on the probabilistic approach such as LDPC codes, and research & development on its practical implementation also picked up speed.


Although the decoding of LDPC codes is computationally intensive, it is inherently well-suited for hardware parallel processing. For this reason, it was preferably adopted in modern large-capacity broadband communication systems that require lower delays and higher throughput.


Since the 2000s, LDPC codes have been extensively adopted in digital communication systems and digital storage systems. These include digital TV satellite broadcasting (DVB-S2), 10 Gigabit Ethernet (IEEE802.3an), WiMAX high-speed data communication (IEEE802.16e), and the 5th generation (5G) mobile communication system, as well as hard disk and solid-state drives. It has become an extremely important fundamental technology that supports our modern digital society.


The realization of the Super Smart Society (Society 5.0), which is envisioned to be the future of our society, will require the cyberspace and the real world to be highly integrated. LDPC codes are expected to contribute significantly to this goal by playing an essential and fundamental role in solving the various challenges of information communication, such as demands for higher speeds, capacity, and reliability, and lower power consumption.


The achievements of Prof. Robert G. Gallager, who has long pioneered the advancement of information and communication technology, are therefore deemed most eminently deserving of the 2020 Japan Prize in the field of "Electronics, Information, Communication".

[Outline of Achievements]

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