FTTH General Parameter and Considerations: Points to be remembered - Technopediasite

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Thursday, January 31, 2019

FTTH General Parameter and Considerations: Points to be remembered

FTTH General Parameter and Considerations: What are the things we should take care of in the work of FTTH, today I will try to cover in this topic. There are three important steps in FTTH work or can it say that these steps are necessary in any work-Planning-Design and Implementation. Today I will discuss the general parameters of FTTH.
It would also be necessary to see this in the FTTH work that to prevent unnecessary expenses in civil works all existing civil infrastructure has to be used as far as possible. It is also necessary for FTTH that ease to install, maintain and operate. Quick service restoration. Design FTTH fiber optic network within 28 dB loss budget.
FTTH General  Parameter and Considerations
FTTH Network general considerations
FTTH OSP Design Parameter
FTTH network should be scalable network. Deployment of technically matured products. Economical component prices. Reduction in CAPEX and OPEX in the long term. Pre-connectorized splitters in CO & FDTs. Splitting ratio will be 1:32 in the FDTs and 1:2 at the central office. If the FDT is more than 13 Km from CO; then 1:32 splitter in the FDT only will be used without the 1:2 at CO.

For Key Account customers; 1:4 splitters to be placed in MH (if the customer is requesting 2 or 4 fibers, then the 1:4 splitter will be placed at customer side).

1:8 splitter to be placed in the exchange connecting the 1:4 splitters for KA before connecting the fibers to the OLT

No 1:2 splitter to be used for KA customers. The 1:8 splitter will be connected to the
OLT port directly. LC/APC connectivity at all stages.

Distribution cables to be loose tube 96F/144F, from Outdoor splitter cabinet.FAT Closures in Joint Box to lay drop cable up to FTB or FOB/ONT.


FTTH General Considerations
Fibers already laid for local networks or other existing services shall be considered for MSAN/VDSL/FTTM/Key Account back-hauling only, no FTTH deployment is allowed on
those cables.

Feeder cables for FDTs can only be newly installed or existing cables feeding previous FDTs but not fully used. MSAN/VDSL/FTTM/Key Account and any other type of customer within the FTTH coverage have to be served through the FDT feeder cables too.

To prevent unnecessary expenses in civil works all existing civil infrastructure has to be used as far as possible. In the case that there is no spare duct available and when the distances are short, a fiber cable may share the available duct space with existing copper (If telecom operator use copper network & copper network available in the same network) cables, if possible through a sub duct, taking into account the following:
If copper cable already exists, lay sub duct over copper cable and then lay the fiber cable in sub duct.
A fiber cable cannot be directly laid over a copper cable or vice versa.


The fiber cables, FDTs & civil infrastructure (ducts, splicing boxes, etc.) location and dimension shall make sure that the given requirements from service coverage viewpoint are covered: redundancy, ultimate feeder dimensioning, Point to Point potential needs, etc.

The OSP fiber counts (Feeder cable dimensioning) from the central office will have to ensure that future capacity requirements are covered (spare capacity) according to the corresponding Fundamental Plan.

Diversity is required for Key Account customers (palaces, airports, police offices, hospitals, ministries, etc.), Telecom Operator Network elements (MSAN, VDSL, GSM sites, FDTs, etc.) and Medium-sized business within Commercial Streets; the civil infrastructure will consider all those route diversity requirements, but the redundant fiber will be given upon service request only.

Infrastructure diversity has also to be given to an FDT boundary on at least 2 sides of the polygon, ideally on the 4 sides, making sure that physical redundancy will be available all the way to the exchange and even between 2 different exchanges.

The requirements of direct fibers for business customers have also to be considered while sizing the main cables. The spare fibers available in junction cables are not to be used for FTTH except for the OLT uplink connectivity.

As far as possible the splicing enclosures in the main cable shouldn’t be frequently operated. The splicing boxes should be located to allow maximum utilization of full drum
length and to avoid short cut lengths.

The main splicing enclosures have 4 in ports and 4 out ports which can be used for
multiple branching of distribution cables.The drop splicing enclosures (FATs) are recommended to be installed inside hand holes close to a block. The FATs have a maximum capacity for 24 drop cables.

FTTH Distribution Cables & Drop cables Sizing
FTTH Distribution cables go from the splitter 1:32 located in the FDT to the FAT, FTB (SDU), ODB (MDU) or indoor optical splitter box (OSB). Loose tube fiber cables of sizes 144F or 96F shall be used depending upon the grouping of villas and number of FATs.

The FAT closures accommodate up to 24 drop cables (144 Fiber Optic max).The max. number of splices inside the FAT should not exceed 96 Fibers.The drop cables / termination box to be used are:
For 1 to 2 DUs per parcel: 8 f.o. cable / TB (TBs with 8 ports will be specified).

For 3 to 8 DUs per parcel: 12 f.o. cable / ODB.
For 9 to 16 DUs per parcel: 24 f.o. cable / ODB.
More than 16 DUs per parcel: OSBs. The no. of fiber strands to the OSB may go from 4 to 12 depending on the Medium Business and Key Account customers in the MDU (potential Point to Point services).

All drop cable fibers will be spliced at TB/ODB/OSB side. Only required fibers should
be spliced at FAT. Examples:

For SDU: 8F spliced at the TB and 2F spliced inside the FAT
For MDU serving 14 DWUs: 24F spliced at the ODB and 14F spliced inside the FAT.

The distribution cable shall be labeled as per the company standard. No splices are allowed between the Telecom Room and Floors. ODBs may be used as intermediate devices if the number of flats per floor is high or the building has many floors.

FTTH Feeder Cables Sizing
The Feeder network covers the link Exchange (OLT, ODF or FDF) - FDT (splitter point). It usually presents the highest networks distances, as the exchange may be far away from the FDT covered area.

The fiber cost is far less than the duct space cost. Hence the provision of the Feeder cables will mandatorily cover the ultimate demand determined in a Fundamental Plan for the area.The routing of Feeder cables has to consider the end-to-end overall "optical budget" available while facilitating connectivity to FDT's.

The total number of splitters per cabinet shall be based on the corresponding Fundamental Plan, and particularly on the DWU count per FDT. The FDTs will have 30% splitter spare capacity to cover potential future demand.

For FTTH projects only 288F feeder cables shall be used (144F cables are to be used only in exceptional cases where there is no further FTTH deployment foreseen in the area).

The 288F cables will be terminated on the exchange using OSP HD-ODF. HD-ODFs accommodate up to 7 feeder cables (x288 fibers/cable=2016 connections).



Friends I have tried to cover the all points for the FTTH General Parameter and Considerations. If something is left to write then you can suggest. I have written about FTTH before, if you want to read, then subscribe to my site and read it. Or if you want to know more about FTTH then tell me the required topic, I will write a separate post on the same topic for you.

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