Patent ID: 7369769
Filing Date: 2008-05-06
Classification: H04J,H04L,H04Q

Abstract:
1. An Ethernet passive optical network (EPON) ring comprising: an optical ring with a first end and a second end; an optical line termination (OLT), which is coupled to the first end and the second end of the optical ring; a plurality of optical network units (ONU), each of which is connected to the optical ring between the first end and the second end, thus defining a plurality of intersections on the optical ring; a plurality of three-port passive optical splitting modules, each of which is installed at one of the intersections and contains three optical ports; wherein the three optical ports in each three-port passive optical splitting module are connected using three two-way passages to allow the ONU to transmit/receive data via the first end and the second end of the optical ring to/from the OLT; a wavelength division multiplexing (WDM) system, which has a double-port end and a single-port end and couples to the three-port passive optical splitting module via the single-port end; an optical receiving unit, which connects to the double-port end of the WDM system for receiving signals from the OLT; a coupler, which connects to the double-port end of the WDM system for receiving signals transmitted by the other ONU; an optical transmitting unit, which connects to the coupler for transmitting signals to the optical ring; and a carrier sensor, which connects to the coupler for receiving signals sent by other ONU, thereby controlling the timing for the optical transmitting unit to send signals to the optical ring.