Network unit and method for monitoring a fiber line

Patent metadata

Field	Value
Publication number	US-2016112119-A1
Application number	US-201314895395-A
Country	US
Kind code	A1
Filing date	Sep 24, 2013
Priority date	Jun 4, 2013
Publication date	Apr 21, 2016
Grant date	—

Abstract

Embodiments herein relate to a method in a network unit for monitoring a fiber line between a radio base station and a radio head in a Fiber to the Radio Head communications network. The Fiber to the Radio Head communications network comprises a ring architecture or a tree architecture of fiber, with Subcarrier Multiplexing, SCM, downstream transmissions and Wavelength Division Multiplexing, WDM, upstream transmissions. The monitoring comprises that the network unit detects an indication of a fault along the fiber line based on monitoring power. The network unit initiates, in response to detect the indication, an Optical x Domain Reflectometry, OxDR, measurement over the fiber line. Additionally, the network unit analyses a trace from the OxDR measurement for localizing the fault or for deciding that the indicated fault is not a fault along the fiber line.

First claim

1 . A method in a network unit for monitoring a fiber line between a radio base station and a radio head in a Fiber to the Radio head communications network, which Fiber to the Radio head communications network comprises a ring architecture or a tree architecture of fiber, with Subcarrier Multiplexing, SCM, downstream transmissions and Wavelength Division Multiplexing, WDM, upstream transmissions, the method comprising:
detecting an indication of a fault along the fiber line based on monitoring power; in response to the detected indication, initiating an Optical x Domain Reflectometry, OxDR, measurement over the fiber line; and analyzing a trace from the OxDR measurement for localizing the fault or for deciding that the indicated fault is not a fault along the fiber line.

2 . A method according to claim 1 , wherein the detecting is based on at least one of: read receiver power from a photo diode in a Radio over Fiber master; detected upstream power to the Radio over Fiber master; and received power.

3 . A method according to claim 1 , further comprising
when the trace indicates no fault, checking a photo diode at the radio base station or the network unit and/or a laser diode of a receiving unit in the communications network, and reporting ( 207 ) the fiber fault when the trace indicates fault to an operator of the network unit ( 14 ) or a node.

4 . A method according to claim 1 , wherein the network unit is a standalone unit or collocated with the radio base station.

5 . A method according to claim 4 , wherein the network unit is a standalone unit, and is operable in two modes, a continuous light source mode for detecting the indication and a trace measure mode for performing the OxDR measurement.

6 . A method according to claim 4 , wherein the network unit is a standalone unit, and is tuneable for adjusting wavelengths.

7 . A method according to claim 4 , wherein the network unit is a standalone unit, and is connectable to the fiber line with a red and blue filter for directing light and/or a tap off connection for tapping off light from the fiber line.

8 . A method according to claim 1 , wherein the Fiber to the Radio head communications network comprises nodes or drop lines with reflectors arranged at least a certain distance from one another to differentiate one another in the trace.

9 . A method according to claim 8 , wherein the certain distance is achieved by a cassette with extra fiber connectable to a node or a drop line.

10 . A method according to claim 1 , further comprising:
comparing ( 201 ) transmit power of a laser diode in a Radio over Fiber master against a threshold value; and when transmit power exceeds the threshold value, checking ( 202 ) the laser diode.

11 . A network unit for monitoring a fiber line between a radio base station and a radio head in a Fiber to the Radio head communications network, which Fiber to the Radio head communications network comprises a ring architecture or a tree architecture of fiber, with Subcarrier Multiplexing, SCM, downstream transmissions and Wavelength Division Multiplexing, WDM, upstream transmissions, wherein the network unit comprises, for monitoring the fiber line:
a detecting circuit configured to detect an indication of a fault along the fiber line based on monitored power; an Optical x Domain Reflectometry, OxDR, circuit configured to initiate, in response to the indication being detected, an OxDR measurement over the fiber line; and an analyzing circuit configured to analyse a trace from the OxDR measurement for localizing the fault or for deciding that the indicated fault is not a fault along the fiber line.

12 . A network unit according to claim 11 , wherein the detecting circuit is configured to detect the indication based on at least one of: read receiver power from a photo diode in a Radio over Fiber master; detected upstream power to the Radio over Fiber master; and received power.

13 . A network unit according to claim 11 , further comprising
a checking circuit configured, when the trace indicates no fault, to check a photo diode at the radio base station or the network unit and/or a laser diode of a receiving unit connected to the radio head in the communications network, and a reporting circuit configured to report the fault when the trace indicates fault to an operator of the network unit or a node.

14 . A network unit according to claim 11 , wherein the network unit is a standalone unit or collocated with the radio base station.

15 . A network unit according to claim 14 , wherein the network unit is a standalone unit, and is configured to operate in two modes, a continuous light source mode for detecting the indication and a trace measure mode for performing the OxDR measurement.

16 . A network unit according to claim 14 , wherein the network unit is a standalone unit, and is configured to adjust wavelengths.

17 . A network unit according to claim 14 , wherein the network unit is a standalone unit, and comprises a red and blue filter connecting the network unit to the fiber and for directing light, and/or a tap off connection for tapping off light from the fiber line.

18 . A network unit according to claim 11 , wherein the Fiber to the Radio head communications network comprises nodes or drop lines with reflectors arranged at least a certain distance from one another to differentiate one another in the trace.

19 . A network unit according to claim 18 , further comprising a cassette with extra fiber connectable to a node or a drop line to achieve the certain distance.

20 . A network unit according to claim 11 , further comprising:
a comparing circuit configured to compare transmit power of a laser diode in a Radio over Fiber master against a threshold value; and a checking circuit ( 807 ) configured to check the laser diode when transmit power exceeds the threshold value.

21 . A computer readable medium containing computer-executable instructions which, once executed by a processor in a network unit, causes the network unit to:
detect an indication of a fault along the fiber line based on monitoring power; in response to the detected indication, initiate an Optical x Domain Reflectometry, OxDR, measurement over the fiber line; and analyze a trace from the OxDR measurement for localizing the fault or for deciding that the indicated fault is not a fault along the fiber line.

Assignees

• Ericsson Telefon Ab L M

Inventors

• Vall-Llosera Gemma
• Dortschy Boris
• Urban Patryk

Classifications

• H04B10/25752

  Optical arrangements for wireless networks · CPC title

• H04B10/071 Primary

  using a reflected signal, e.g. using optical time domain reflectometers [OTDR] · CPC title

• H04J14/0265 Primary

  Multiplex arrangements in bidirectional systems, e.g. interleaved allocation of wavelengths or allocation of wavelength groups · CPC title

• H04J14/0249

  for upstream transmission, e.g. ONU-to-OLT or ONU-to-ONU · CPC title

• H04J14/0298

  with sub-carrier multiplexing [SCM] · CPC title