1. [1] ITU-T Recommendation G.983, “Broadband optical access systems based on Passive Optical Networks (PON),” 2005.
2. [2] ITU-T Recommendation G.989, “40-Gigabit-capable passive optical networks (NG-PON2): Definitions, abbreviations and acronyms,” 2015.
3. [3] ICT facts and figures 2017, https://www.itu.int/en/ITU-D/Statistics/Documents/facts/ICTFactsFigures2017.pdf, 2017.
4. [4] http://www.soumu.go.jp/main_content/000371278.pdf
5. [5] http://ictr.co.jp/report/20170724.html