Method and system for passive optical network diagnostics
View Patent ↗A method and system for identifying faults in a passive optical network (PON). The method comprises acquiring at an optical network terminal of the PON at least one parameter indicative of at least one malfunction in at least one optical network unit of the PON, and identifying each malfunction from the at least one parameter. The parameters measured include, for each ONU, laser power, sync-lock and -unlock time and bit error rates. The information at the OLT is acquired remotely and in digital form, without use of any physical probing of any point or element in the PON. The system includes a temporal measurement module and a power laser measurement module coupled to a central processing unit that can extract fault information from digital data processed in the two modules.
1. A method for identifying a malfunction in a PON which includes a central OLT and a plurality of ONUs, the method comprising the steps of: at the OLT, for each ONU:
(a) measuring a sync-lock time and a bit rate during each of a plurality of grant periods of a specific ONU, wherein the measurements are performed in real time;
(b) comparing each of said measured sync-lock time and said measured bit error rate with a respective reference value to obtain a comparison result, wherein said reference value for said measured sync-lock time includes a known value of said sync-lock time; and
(c) identifying a malfunction, selected from the group consisting of an early burst reception and a late burst reception, based on the comparison result.
2. The method of claim 1 , further comprising the steps of:
(d) measuring a transmitter laser power of the specific ONU; and
(e) comparing said measured transmitter laser power to a reference value includes a known laser power value.
3. The method of claim 2 , further comprising the step of:
(f) identifying an unstable laser signal.
4. The method of claim 2 , further comprising the step of:
(f) identifying a malfunction selected from the group consisting of a weak laser signal and a strong laser signal.
5. The method of claim 2 , further including the step of:
(f) determining whether the specific ONU is logically connected.
6. The method of claim 5 , further comprising the step of:
(g) identifying a laser stuck at 1.
7. A system for identifying faults in a PON which includes an OLT and a plurality of ONUs, the system comprising:
(a) a timing measurement module coupled to the OLT and operative to provide a measured sync-lock time for each ONU from a comma sync data stream;
(b) a BER measurement module operative to periodically sample transmission errors for each ONU from a BER detection data stream, thereby providing a measured BER; and
(c) a central processing unit to extract an ONU status indicative of a fault selected from the group consisting of an early burst reception and a late burst reception based on a comparison of each of said measured sync-lock time and said measured BER with a respective reference value thereof;
wherein said reference value for said sync-lock time includes a known value of said sync-lock time.
8. The system of claim 7 , further comprising a grant monitor unit coupled and operative to notify the timing measurement and BER measurement modules of an expected granted ONU.
9. The system of claim 8 , further comprising a MAC unit used to detect code errors in an incoming data stream and to provide the BER detection data stream to the BER measurement module and the comma sync data stream to the timing measurement module.
10. The system of claim 9 , wherein the incoming data stream is an optical data stream provided by an optical transceiver.
11. The system of claim 7 , wherein said timing measurement module is operative to provide, during a respective plurality of grant periods, a respective plurality of values of said measured sync-lock time.
12. The system of claim 7 , further comprising:
(d) a logic module operative to track the expected transmissions of each ONU and including a grant monitor operative to notify the timing measurement module of an expected granted ONU.
13. The system of claim 7 , further comprising:
(d) a laser power measurement module coupled to the OLT and operative to provide at least one laser power parameter for each ONU.
14. The system of claim 13 , wherein the laser power measurement module is coupled to and operative to receive a digital laser power signal from an analog laser.
15. The system of claim 13 , wherein said laser power measurement module is operative to provide, during a plurality of grant periods for each ONU, a respective plurality of values of said at least one laser power parameter.
16. A method for identifying a malfunction in a PON which includes a central OLT and a plurality of ONUs, the method comprising the steps of: at the OLT, for each ONU:
(a) measuring a sync-unlock time and a bit rate during each of a plurality of grant periods of a specific ONU, wherein the measurements are performed in real time;
(b) comparing each of said measured sync-unlock time and said measured bit error rate with a respective reference value to obtain a comparison result, wherein said reference value for said measured sync-unlock time includes a known value of said sync-unlock time; and
(c) identifying a malfunction, selected from the group consisting of an early end of burst and a late end of burst, based on the comparison result.
17. A system for identifying faults in a PON which includes an OLT and a plurality of ONUs, the system comprising:
(a) a timing measurement module coupled to the OLT and operative to provide a measured comma sync-unlock time for each ONU;
(b) a BER measurement module operative to periodically sample transmission errors for each ONU from a BER detection data stream, thereby providing a measured BER; and
(c) a central processing unit to extract an ONU status indicative of a fault selected from the group consisting of an early end of burst and a late end of burst based on a comparison of each of said measured sync-unlock time and said measured BER with a respective reference value thereof;
wherein said reference value for said sync-unlock time includes a known value of said sync-unlock time.