Patent ID: 8355634
Filing Date: 2013-01-15
Classification: H04B,H04Q

Abstract:
1. A passive optical network in which a plurality of optical network units (ONU) are optically connected to central office optical line termination (OLT) equipment for bi-directional data communications and the central office provides control specifying instruction, for each of the media access controller (MAC) contained within optical network units, said instructions defining time slices during which the optical network unit is authorized to transmit upstream data thereby meeting TDMA protocol, said optical network unit configured for automatic shutdown, comprising: a burst mode light source driver circuit contained within optical network units adapted to drive a light source in response to upstream data received at a digital data input, and further having said time slice frame delivered by said media access controller and shutdown inputs; a burst mode light source connected to said driver circuit and configured to generate an upstream optical signal having an upstream optical power level and representative of said upstream data received at said digital data input for transmission from said optical network unit to said central office optical line termination (OLT) equipment; an authorization circuit contained within optical network units responsive to said control to form an ON frame state signal during time slices in which transmission of said upstream optical signal from said optical network unit is authorized and an OFF frame state signal during time slices in which said transmission of said upstream optical signal is prohibited; a monitoring circuit contained within optical network units operable to monitor said burst mode light source upstream output optical power level; a comparison circuit contained within optical network units connected to said monitoring circuit and operable to compare said upstream optical output power level to a predetermined threshold power level and generate: (i) an ON monitor state signal while said upstream optical power level exceeds said predetermined threshold power level; and (ii) an OFF monitor state signal while said upstream optical power level is lower than said predetermined threshold power level; and a deactivation circuit contained within optical network units connected to said driver circuit and operable to detect the presence of said OFF monitor state signal indicative of a non functioning light source or low optical power output light source received from said comparison circuit in coincidence with presence of said ON frame state signal received from said authorization circuit and, in response, to output a shutdown signal; a deactivation circuit connected to said driver circuit and operable to detect the presence of said ON monitor state signal received from said comparison circuit in coincidence with presence of said OFF frame state signal received from said authorization circuit and, in response, to output a shutdown signal; and wherein said driver circuit is connected at said to frame state signal input and to shutdown signal from said deactivation circuit, and said driver circuit is configured to: (i) drive said light source to transmit said upstream data while said frame state signal is ON and said shutdown signal is not present; (ii) inhibit said light source while said frame state signal is OFF; and (iii) deactivate said light source upon receipt of said shutdown signal.