The present invention discloses a method for transmitting
signal between a central channel
processing Main Unit (MU) and one or more Remote Radio Units (RRUs) by using SDH / OTN in Centralized
Base Transceiver Station system using
remote radio head (RRH) technology. The method includes: dividing the
communication interface between the MU and the RRUs into a user plane and a control plane, the user plane mainly for carrying I / Q sampling data concerning the user data, and the control plane mainly for carrying the data concerning control signaling; forming the I / Q sampling data concerning the user data carried by the user plane into an I / Q data frame via an I / Q data frame
adaptation layer, then forming the I / Q data frame into a GFP frame via GFP and transmitting it on SDH / OTN; and carrying the control signaling of the control plane on UDP / IP and / or TCP / IP, and further carrying IP packet on PPP and forming it into a frame by HDLC, transmitting the HDLC frame including the control plane signaling on the SDH / OTN via the
control character channel of the GFP frame. According to the present invention, the existing SDH / OTN
transmission network is utilized directly, which further reduces the management and maintenance operation needed for
signal transmission, as well as networking cost.