In‐house Cabling process in FTTH

In‐house Cabling process in FTTH : Before this article, I have also written about FTB, FTB means fiber termination point with test facilities between drop cables and inside wiring for customer’s building. The FTB shall be installed in the customer building's outside wall but in this article I will explain about the In house Cabling process in FTTH.

Whenever we talk about the cable in the FTTH project, it is often we assume cable upto the customer building walls or we understand that a DP / FTB (distribution Box) install at the wall of customer building and it is the last termination point of cable. But a part of FTTH project is also in-house cabling which has to be completed.

In-house cabling details 

In‐house Cabling process in FTTH

Reference model of In‐house cabling

First of all I talk about the reference model of in-house cabling which will make it easier for all of you to understand. Within the in-house cabling the  basic network elements are based on two network structures-

1. direct drop architecture (Point to Point)

2. riser architecture with or without floor distribution boxes.

In-house cabling

In‐house cabling reference model

The Interrelation between the BEP and the Floor Distributor and/or the Optical Termination Unit is known as the riser cabling. This is a common network architecture that is used in MDUs.

Riser fiber cables or ducts fed with fibers are usually  installed in existing cable conduits e.g. electrical installations or individually installed cable conduits for the FTTH network. This is normal to install a vertical riser from the basement or upper floor of a building.

The vertical riser is the most time consuming installation part of in-house cabling, especially in the section where local fire regulations need to be taken into account as they often pass stairways used as escape routes.

In-house cabling depend on the type of architecture, the number of fibers required for per subscriber and the number of apartments in the building, the riser cables can have various structures: mono fiber, bundles of mono fiber, or bundles of multiple fibers. To understand very easily, you have to look at the image below carefully-

riser architecture

In-house cabling riser architecture

Since these cables are installed in difficult conditions (eg. low bending radius at the edges) new twist-insensitive fibers should be considered. As the purpose of this article is to clarify the aspects of drop cabling, building entry point, in-house cabling and a optical telecommunications outlet.

Building entry point - BEP

In-house cabling the BEP allows the transition from outdoor to indoor cable. The type of transition can be a splice or a removable connection.

Floor distributor - FD 

The floor distributor is an optional element that allows the transition from vertical to horizontal indoor cable.

In‐house cabling

In-house cabling connects the BEP to the OTO. The main components are an optical indoor cable or similarly, the installation of blowing-based, fiber elements.

Optical telecommunications outlet - OTO

OTO is a fixed connecting device where the fiber-optic indoor cable terminates. The optical telecommunications outlet provides an optical interface to the instrument cord of the ONT / CPE.

Optical network termination - ONT

The ONT terminates at the subscriber premise and includes an electro-optical converter in the FTTH optical network . The ONT and CPE may be integrated.

Customer premises equipment - CPE / SPE

SPE / CPE is a active device at the subscriber end.The subscriber or customer premises equipment is any active device like- set-top box, through these devices FTTH services (high-speed data, TV, telephony, etc.) provided to the subscriber end. The ONT and SPE/CPE may be integrated.

Home cabling

Distribution of a wide range of applications, TV, telephone, internet access etc it all provided by the home cabling within the premises. Any specific hardware is not part of the home cabling.

User equipment

Subscriber uses the devices as per their convenience and requirement like TV, phone, or personal computer, allows the subscriber to access services.

In‐house cabling fiber and cable

Fiber characteristics is also a main important subject in the in-house cabling, BEP is the point at which fibers from the drop cabling and fibers from the in-house cabling have to be connected.

Specifications fibers for the in-house cabling are described in the different standard of the fiber categories and must fulfill certain requirements as- 

Outdoor cables- G.652 D, Outdoor cables - G.657 A and Indoor cables - G.657 A.

Bend radius requirements

Bend radius can be consider 30mm and above. For single mode fibers G.652D or G.657A in the BEP and outdoor cable sections bend radius shall be 30mm and above but bending radius in the OTO and indoor cable type for G.657A fibers shall be 15mm and above.

Cable type

Optical fiber used for installations at the BEP required optical loose tube fiber cables.Fiber used for installations at the BEP required optical loose tube fiber cables with micro-duct cabling for installation by blowing. Out door cable operating temperature range is between –30°C and +70°C. Out door cable provide 4 fibers between the BEP and each OTO and operating temperature range of indoor cable will be –20°C and +60°C.

As per standard colors, buffered fibers are color coded to differentiate the fibers within the cable. Color coding provide the facility to Installer to easily identify the fiber at both ends. It also indicates the appropriate position of each fiber in the fiber link and cable.

Splice at the BEP

At the BEP fusion splicing is used,there are some special things to keep in mind during fusion splicing on the BEP. Max. attenuation of splices - 0.15 dB , Return loss - > 60 dB and operating temperature range - –25°C to 70°C.

Connection box and Splice tray at the BEP

According to the size of building the size of the fiber management system used at BEP. To understand you, I am putting the image of both below so that you can understand easily.

Connection box and splice tray used in in-house cabling

connection box and splice tray

You can also read these important below articles-

1. Optical Distribution Box (ODB) in FTTH Network

2. Role of Fiber Termination Box (FTB) in FTTH Network

3. Laying the optical drop cable in the FTTH

4. Optical Fiber Cables Sizing in FTTH Network

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