Ethernet passive optical network ring and its method of authorization and collision detection

An authorization method for an EPON ring with an optical ring, an OLT connected between the two ends of the optical ring, and a plurality of ONU that use a plurality of three-port passive optical splitting modules to connect to the optical ring, so that each ONU receives/transmits data via the two ends of the optical ring from/to the OLT through the connection of three two-way passages inside the three-port passive optical splitting modules, the method verifying a user who uses an ONU to enter the optical network and comprising the steps of:

• receiving a signal sent from the ONU of the user via the two ends of the optical ring;
• obtaining the two times of receiving the signal via the two ends;
• computing a difference of the two times;
• and
• using the time difference to verify the user's identity.

A collision detection method for an EPON ring with an optical ring, an OLT connected between the two ends of the optical ring, and a plurality of ONU that use a plurality of three-port passive optical splitting modules to connect to the optical ring, so that each ONU receives/transmits data via the two ends of the optical ring from/to the OLT through the connection of three two-way passages inside the three-port passive optical splitting modules, the method verifying there is no more than one ONU transmitting data at a time on the optical ring to reduce chances of collisions and comprising the steps of:

• receiving a signal transmitted by the optical ring using the three-port passive optical splitting module;
• filtering the signal;
• verifying that the signal is transmitted by other ONU;
• and
• forbidding the ONU from transmitting the signal.