https://blog.wongcw.com/2020/09/01/open-ran%e5%85%a8%e7%90%83%e9%80%b2%e6%93%8a%e8%8f%af%e7%82%ba%e4%b8%8d%e5%8f%af%e5%bf%bd%e8%a6%96%e7%9a%84%e5%b0%8d%e6%89%8b/