US 11,909,523 B2Granted

Using shortened codewords in passive optical networks

AssigneeNokia Solutions and Networks Oy

InventorsYannick Lefevre, Amitkumar Mahadevan, Werner Van Hoof

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Abstract

An upstream (US) optical line terminal (OLT) for a passive optical network having at least one downstream (DS) optical network unit (ONU). The OLT generates a trigger signal indicating a need to receive at least one US burst having a shortened codeword for a first forward error-correction (FEC) code. Based on the trigger signal, the OLT transmits a DS message instructing the ONU to transmit an US burst having a shortened codeword. The OLT receives and decodes the US burst having the shortened codeword using the first FEC code. During periods of high bit-error rate, the shortened codewords increase the ability of the OLT to decode the US bursts and keep communications from the ONU alive. The OLT can use the decoded US bursts to measure BER and, if appropriate, instruct the ONU to use a different FEC code.

Claims32

Dependent claims

An upstream (US) optical line terminal (OLT) for a passive optical network (PON) having at least one downstream (DS) optical network unit (ONU), the OLT comprising a processor configured to control (i) transmit operations of a transmitter of the OLT and (ii) receive operations of a receiver of the OLT, wherein the OLT is configured to:

generate a trigger signal indicating a need to receive at least one US burst having a shortened codeword for a first forward error-correction (FEC) code;
based on the trigger signal, transmit, to the ONU, a DS message instructing the ONU to transmit, to the OLT, an US burst having a shortened codeword;
receive, from the ONU, the US burst having the shortened codeword;
and
decode the US burst having the shortened codeword using the first FEC code, wherein at least one of (a)-(h):
(a) the trigger signal is configured to override normal bandwidth assignment processing by the OLT's Dynamic Bandwidth Assignment (DBA) engine;
(b) the OLT is configured to determine, based on zero, one, or more detected errors in the shortened codeword, to instruct the ONU to replace the first FEC code with a different FEC code for future US bursts;
(c) the shortened codeword comprises a maintenance message;
(d) the US burst comprises two or more shortened codewords;
(e) the US burst comprises a single codeword, wherein the single codeword is a shortened codeword;
(f) each shortened codeword has a codeword size that is smaller than a specified upper limit that is smaller than the codeword size of a full-size codeword;
(g) contents of the shortened codeword are known a priori by the OLT such that the OLT can detect errors in the shortened codeword without having to decode the shortened codeword;
and
(h) the OLT is configured to maintain one or more of:
(1) a first counter value for a number of information bits plus parity bits in successfully corrected codewords;
and
(2) a second counter value for a number of corrected information bits plus parity bits in successfully corrected codewords.

14 more elements

A method for a US OLT for a PON having at least one DS ONU, the method comprising the OLT:

generating a trigger signal indicating a need to receive at least one US burst having a shortened codeword for a first FEC code;
based on the trigger signal, transmitting, to the ONU, a DS message instructing the ONU to transmit, to the OLT, an US burst having a shortened codeword;
receiving, from the ONU, the US burst having the shortened codeword;
and
decoding the US burst having the shortened codeword using the first FEC code, wherein at least one of (a)-(h):
(a) the trigger signal is configured to override normal bandwidth assignment processing by the OLT's Dynamic Bandwidth Assignment (DBA) engine;
(b) the OLT is configured to determine, based on zero, one, or more detected errors in the shortened codeword, to instruct the ONU to replace the first FEC code with a different FEC code for future US bursts;
(c) the shortened codeword comprises a maintenance message;
(d) the US burst comprises two or more shortened codewords;
(e) the US burst comprises a single codeword, wherein the single codeword is a shortened codeword;
(f) each shortened codeword has a codeword size that is smaller than a specified upper limit that is smaller than the codeword size of a full-size codeword;
(g) contents of the shortened codeword are known a priori by the OLT such that the OLT can detect errors in the shortened codeword without having to decode the shortened codeword;
and
(h) the OLT is configured to maintain one or more of:
(1) a first counter value for a number of information bits plus parity bits in successfully corrected codewords;
and
(2) a second counter value for a number of corrected information bits plus parity bits in successfully corrected codewords.

14 more elements

Dependencies are inferred from the claim text.

Facts

Application: 17/573,930Filed 12 Jan 2022
Published: US 2023/0224074 A113 Jul 2023
Granted: 20 Feb 2024
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

H04L 1/0009
Systems modifying transmission characteristics according to link quality, e.g. power backoff: by adapting the channel coding
H04L 1/0042
Arrangements at the transmitter end: encoding specially adapted to other signal generation operation, e.g. in order to reduce transmit…
H04B 10/27
Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing…
H04L 1/0025
Characterised by the signalling: transmission of mode-switching indication

Family

US 2023/0224074 A1Pre-grant publication · published 13 Jul 2023
US 11,909,523 B2This patent

From the US filing history. Foreign family members aren’t listed.

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