Page 1164 - 5G Basics - Core Network Aspects

2 Transport aspects

A payload missing indication (PMI) is a signal sent downstream as an indication that upstream at the source
point of the signal none of the frequency slots have an optical tributary signal. This indicates that the
transport of the optical tributary signals is interrupted or no optical tributary signals are present.
A PMI signal is generated in the adaptation source function and it is detected in the trail termination sink
function which suppresses the LOS defect that arises under this condition.

16.1 OTS maintenance signals

16.1.1 OTS payload missing indication (OTS-PMI)
OTS-PMI is generated as an indication that the OTS payload does not contain an optical signal.

16.2 OMS maintenance signals

Three OMS maintenance signals are defined: OMS-FDI-P, OMS-FDI-O and OMS-PMI.
16.2.1 OMS forward defect indication – Payload (OMS-FDI-P)

OMS-FDI-P is generated as an indication of an OMS server layer defect in the OTS network layer.
16.2.2 OMS forward defect indication – Overhead (OMS-FDI-O)

OMS-FDI-O is generated as an indication when the transport of OMS OH via the OSC is interrupted due to a
signal fail condition in the OSC.
16.2.3 OMS payload missing indication (OMS-PMI)

OMS-PMI is generated as an indication when none of the frequency slots contain an optical tributary signal.

16.3 OCh and OTiSA maintenance signals
Three OCh and OTiSA maintenance signals are defined: OCh-FDI-P, OCh-FDI-O and OCh-OCI.

16.3.1 OCh and OTiSA forward defect indication – Payload (OCh-FDI-P, OTSiA-FDI-P)
OCh-FDI-P and OCh-FDI-P are generated as an indication for an OCh and OTSiA server layer defect in the
OMS network layer.
When the OTUk or OTUCn is terminated, the OCh-FDI-P and OTSiA_FDI-P is continued as an ODUk-AIS
signal.

When the OTUCn is not terminated, the OCh-FDI-P and OTSiA_FDI-P are continued as an OTUCn-AIS signal.
16.3.2 OCh and OTiSA forward defect indication – Overhead (OCh-FDI-O, OTSiA-FDI-O)

OCh-FDI-O is generated as an indication when the transport of OCh OH via the OSC or OCC is interrupted
due to a signal fail condition in the OSC or OCC.

16.3.3 OCh and OTiSA open connection indication (OCh-OCI, OTSiA-OCI)
The OCh-OCI/OTSiA-OCI signal indicates to downstream transport processing functions that the OCh/OTSiA
connection is not bound to, or not connected (via a matrix connection) to a termination source function.
The indication is used in order to distinguish downstream between a missing OCh/OTSiA signal due to a
defect or due to the open connection (resulting from a management command).
NOTE – OCI is detected at the next downstream OCh or OTSiA trail terminating equipment. If the connection was
opened intentionally, the related alarm report from this trail termination should be disabled by using the alarm
reporting control mode (refer to [ITU-T M.3100]).

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