Ledger-based Points Transfer System in LPWAN: From Disaster Management Aspect. - Xin Qi 002; Keping Yu; Toshio Sato; Kouichi Shibata; Eric Brigham; Takanori Tokutake; Rikiya Eguchi; Yusuke Maruyama; Zheng Wen 001; Kazuhiko Tamesue; Yutaka Katsuyama; Kazue Sako; et al. (ICT-DM, 2021)