Ranging method in FTTR network, SFU, MFU and system

The invention discloses a distance measurement method in an FTTR network. The method comprises the following steps: an SFU judges whether to enter a short-distance working mode; and if yes, carrying out distance measurement according to the received downlink broadcast Ranging Time message and the BWmap information. The invention also discloses another ranging method in the FTTR network. The method comprises the following steps: periodically issuing messages by the MFU to indicate whether a short-distance working mode is adopted in a system or not and whether the SFU completes ranging or not; and the MFU periodically sends BWmap information and broadcasted Ranging Time information, and the BWmap information and the broadcasted Ranging Time information comprise the average equilibrium value of the SFU subjected to distance measurement in the current system, so that the SFU not subjected to distance measurement is indicated to complete distance measurement in a short-distance mode. According to the ranging metho