US 2002/0171895 A1 · Automatic ranging in a passive optical network

Abstract

The invention advantageously provides automatic ranging in a passive optical network or PON. A PON with automatic ranging according to the invention comprises an optical line terminal (OLT) connected to a plurality of optical network units (ONUs), a new ONU to be connected to the OLT, and at least one OLT frame sent from the OLT to the ONUs. The OLT frame according to the invention further comprises an OLT preamble alerting a particular ONU of the plurality of ONUs of the OLT frame, an OLT start frame delimiter (SFD) indicating a start of the OLT frame, an OLT header identifying the OLT, an OLT ranging time stamp sending a ranging time clock to one of the ONUs, an OLT churning control for a churning function of the PON, an ONU number instructing the particular ONU to respond to the OLT with a ranging time stamp and a churning key, and an OLT end frame delimiter (EFD) indicating an end of the OLT frame. Upon receipt of the OLT frame from the OLT by the particular ONU of the plurality of ONUs, an ONU frame is sent back to the OLT. The ONU frame according to the invention further comprises an ONU preamble alerting the OLT of the ONU frame, an ONU start frame delimiter (SFD) indicating a start of the ONU frame, an ONU header identifying the particular ONU, an ONU ranging time stamp responding to the ONU number, an ONU churning key responding to the ONU number, and an ONU end frame delimiter (EFD) indicating an end of the ONU frame. The ONU number in the ONU frame according to the invention further comprises an ONU number preamble alerting the particular ONU of the ONU number, a start sub-frame delimiter (SSD) indicating a start of the ONU number, an ONU ID identifying the particular ONU, an automatic bandwidth adjustment beginning (ABAB), and an automatic bandwidth adjustment terminating (ABAT). With the automatic ranging method and system according to the invention, a PON can advantageously maintain its operation without serious interruption as ONUs are added or removed from the PON. Furthermore, the safety guard time between consecutive data frames in the upstream or downstream transmission is advantageously and appropriately calculated as ONUs are added to or removed from the PON in accordance with the invention.

Claims17

Dependent claims

A passive optical network (PON) with automatic ranging comprising;

an optical line terminal (OLT) connected to a plurality of optical network units (ONUs);
a new ONU to be connected to the OLT;
at least one OLT frame sent from the OLT to the ONUs, the OLT frame comprising:
an OLT preamble alerting a particular ONU of the plurality of ONUs of the OLT frame;
an OLT start frame delimiter (SFD) indicating a start of the OLT frame;
an OLT header identifying the OLT;
an OLT ranging time stamp sending a ranging time clock to one of the ONUs;
an OLT churning control for a churning function of the PON;
an ONU number instructing the particular ONU to respond to the OLT with a ranging time stamp and a churning key;
and
an OLT end frame delimiter (EFD) indicating an end of the OLT frame.

8 more elements

A method for a passive optical network (PON) comprising a plurality of optical network units (ONUs) and an optical line terminal (OLT), the method comprising the steps of:

determining if the PON is a cold PON;
if the PON is a cold PON,
(20) inputting an ONU ID into an OLT frame from the OLT;
(21) sending the OLT frame to each of the ONUs;
(22) returning a respective ONU frame for each of the plurality ONUs to the OLT if an automatic bandwidth adjustment beginning (ABAB) in an ONU number in the respective ONU frame is recognized;
(23) calculating a round trip time for each of the ONUs in returning their respective ONU frames to the OLT;
(24) arranging the respective ONU frames for the plurality of ONUs in a transmission sequence in accordance with the respective calculated round trip time for each of the ONUs;
(25) calculating a time difference for each group of two consecutive ONU frames for the plurality of ONUs in the transmission sequence;
(26) calculating an arrived time of the respective calculated round trip time for each of the ONUs in the transmission sequence;
(27) masking the time difference for each group of two consecutive ONU frames for the plurality of ONUs in the transmission sequence into a result;
(28) setting a time difference value for each group of two consecutive ONU frames to its respective predetermined value if the masked result in the masking step is less than or equal to the predetermined value;
(29) setting the time difference value to a difference of the predetermined value and the masked result if the masked result in the masking step is greater than the predetermined value;
(30) recalculating the ABAB and an automatic bandwidth adjustment terminating (ABAT) in the ONU number according to the time difference value;
(31) resending the OLT frame to each of the ONUs with the recalculated ABAB and ABAT;
(32) returning the respective ONU frame for each of the plurality ONUs to the OLT in the transmission sequence if the recalculated ABAB in the ONU number is recognized;
(33) recalculating an arrived time of the respective calculated round trip time for each of the ONUs in the transmission sequence, and respective begin time and end time for the arrived time;
(34) recalculating the time difference for each group of two consecutive ONU frames for the plurality of ONUs in the transmission sequence;
(35) determining if the recalculated time difference is greater than or equal to a predetermined safety guard time.

15 more elements

Dependencies are inferred from the claim text.

Automatic ranging in a passive optical network

Life of this patent

Automatic ranging in a passive optical network

Life of this patent

Abstract

Claims17