1. 802.11ah-2016 - IEEE Standard for Information technology—Telecommunications and information exchange between systems-Local and metropolitan area networks—Specific requirements-Part 11: Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 2: Sub 1 GHz License Exempt Operationhttp://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=7920364{&}isnumber=7920363
2. https://www.google.com.hk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0ahUKEwiOxdKohe3YAhWHGJQKHeGJAAEQFggxMAE&url=https%3A%2F%2Fwww.rs-online.com%2Fdesignspark%2Frel-assets%2Fds-assets%2Fuploads%2Fknowledge-items%2Fapplication-notes-for-the-internet-of-things%2FLoRaWAN%2520Specification%25201R0.pdf&usg=AOvVaw0AtFxrSIWv0lFLj3ts_9Gv