说明：  华为培训新员工的教材《通信技术概论》，不可多得的经验型教材，适合有一定基础的通信技术人员阅读。请勿用于商业用途。
(Huawei training new teaching staff, " Communication Studies" , a rare experience-based teaching materials, suitable for a foundation of communication and technical personnel to read. Do not for commercial purposes.)