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FTTx Passive Infrastructure Technical Solution

OUTSIDE PLAN

FTTx Technical Solution

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TABLE OF CONTENTS

1. INTRODUCTION .......................................................................................................................................................................3

2. DESIGN & DEPLOYMENT SOLUTION ................................................................................................................................4

2.1. POINT OF PRESENCE ...............................................................................................................................................................5

2.2. FEEDER CABLING ....................................................................................................................................................................5

2.3. DISTRIBUTION HANDHOLE (FIRST CONCENTRATION POINT-FCP) .............................................................................................7

2.4. DISTRIBUTION CABLING .........................................................................................................................................................8

2.5. DROP MANHOLE (SECOND CONCENTRATION POINT-SCP) ......................................................................................................8

2.6. DROP CABLING ....................................................................................................................................................................11

2.7. DROP CABLING MANAGEMENT .............................................................................................................................................12

2.8. BUILDING TERMINATION ......................................................................................................................................................12


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1. Introduction

The implementation of FTTx access network remains a big challenge for every network builder and operator. The main reasons are the choice of the proper technology in order to support the high bandwidth demanded services as well as the large number of subscribers and the adaptation of this technology into a low cost passive network’s infrastructure. When providing FTTx networks, it is key to understand the aforementioned challenges. Some of these may present conflicts between functionality and economic demands. Key functional requirements for a FTTH network will include:

• Provision of high bandwidth services and content to each customer, with no restrictions

• Support for the required network architecture design (the fibre infrastructure must remain flexible at all times)

• Connection by fibre of each end subscriber directly to the serving equipment, avoiding intermediate active equipment (e.g. a fully passive optical network)

• Support future network upgrade and expansion The economic requirements will include (but are not limited to):

• A successful business case, providing the lowest possible Capital Expenditure (CAPEX) and Operating Expenditure (OPEX) solutions for affordable infrastructure deployment

• Minimal deployment disruption where possible, to gain acceptance from network owners and to benefit FTTH subscribers

The scope of this document is to provide a FTTx passive infrastructure solution which has the ability to operate under different optical access technology.


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2. Design & Deployment Solution

The general FTTx architecture which will be described in this section is illustrated in Figure 1.

Fig. 1: The proposed optical access network topology

Expanding outwards from the POP towards the Subscriber, the key FTTH Infrastructure Elements needed are: 1. POP 2. Feeder Cabling 3. Primary Fibre Concentration Points (Distribution Handhole) 4. Distribution Cabling 5. Secondary Fibre Concentration points (Drop Manhole) 6. Drop Cabling 7. Internal Cabling (subscriber end)


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2.1. Point of Presence

The Point of Presence (POP), acts as the starting point for the optical fibre path to the subscribing customer. The function of the POP is to house all active transmission equipment; manage all fibre terminations and facilitate the interconnection between the optical fibres and the active equipment. The physical size of the POP is ultimately determined by the size and capacity of the FTTx area in terms of subscribers and future upgrades. The POP may form part of an existing or new building structure. The main network cables entering the POP will terminate and run to the active equipment. The feeder cables will also connect to the active equipment and run out of the POP building and onto the FTTx network area. All other physical items are used to manage the optical fibres within the POP. Separate cabinets and termination shelves may be considered for equipment and individual fibre management to simplify fibre circuit maintenance as well as avoid accidental interference to sensitive fibre circuits. The key Network Infrastructure elements within an Access Node Building are:

• Optical Distribution Frames (ODFs)

• Cable guiding system

• Uninterrupted Power Supply (UPS)

• Climate control

In addition the following systems have been taken into account:

• Emergency Cut Off System (A/C units)

• Fire Detection – Suppression System using FM-200

• Emergency Lighting

• Access Control System

• Water Detection System

• Alarm System

2.2. Feeder cabling

The feeder cabling runs from the POP to the distribution hanhole. The feeder cabling may cover a few kilometres distance before termination and will generally consist of larger fibre count cables (100s of fibres) to provide the necessary fibre capacity to serve the FTTx area. For underground networks, suitably sized ducts will be required to match the cable design and additional ducts considered for network growth and maintenance. Existing infrastructures may be available in full or in part to help balance costs. In terms of our solution there are two feeder cabling proposals. The first makes use of microcables which can carry up to 144 fibers each (Figure 3). These cables are blown into the already installed into the trenches multiducts. The size of multiducts that have been chosen is (12mm/10mm).


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Fig. 3: Microcable (144 f) installed into a multiduct

The second proposal makes use of reinforced microcables (144 fibers) which are blown into HDPE (Figure 4) ducts with size 50mm. Both solutions offer a robust cabling topology, with low cost and complexity and provide the ability to support the several optical access technologies such as P2P and GPON.

Fig. 4: Reinforced microcable (144 f) installed into a HDPE (50 mm) duct

The size of trenches in which the aforementioned cabling techniques will be installed must be in line with the several national construction laws. For the case of our models the trenches (for the several cabling) will have the form of figure 5.

10mm

12mm

Multiduct 12/10

Microcable 144f

14mm HDPE

Reinforced 144f


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Co

ncre

te

C2

0

Asphalt

NETWORK ACCESS

Co

ncre

te

C2

0

NETWORK ACCESS

Fig. 5: Trenches 450-650mm depth,130-200mm wide paved (left) and Trenches 450-650mm

depth,130-200mm wide un paved (right)

2.3. Distribution Handhole (first concentration point-FCP)

The feeder cabling will eventually need to convert to smaller distribution cables. This is achieved at the first point of flexibility within the FTTx network, which can be generally termed the First Concentration Point. Ideally, the Distribution Handhole (Figure 6) should be positioned as close to subscribers as possible, shortening subsequent distribution cable lengths and hence minimising further construction costs. In principle, the location of the Handhole may be determined by other factors such as the position of ducts and access points. Feeder cable fibres are broken down and spliced into smaller groups for further routing via the outgoing distribution cables. The FCP unit take the form of an underground cable joint closure designed to handle a relatively high number of fibres and connecting splices (if it is needed). In this case, entry and further re-entry into a Distribution Handhole will be required to configure or reconfigure fibres or to carry out maintenance and fibre testing. This activity must be achieved without any possibility of disturbing existing fibre circuits. Underground joint closures are relatively secure and out of sight but immediate access may be hindered as special equipment is required for access. However, immediate access to fibre circuits should be relatively simple. In specific topology’s solution the Distribution Handhole remain simple and there isn’t any need for cable joint closure because each multiduct must be spliced into smaller groups of ducts (Figure 6). The size of handholes in which the aforementioned cable jointer/splitter will be installed must be in line with the several national construction laws. For the case of our models the distribution handholes will have the form of figure 6.


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Fig. 6: Handhole blueprint (80X80X95 cm outer) with one cover (left) and Handhole

blueprint (144x89x117 cm outer) with two covers

2.4. Distribution Cabling

The distribution cables run from the FCP further into the FTTX network and closer to the subscriber base. Distribution cabling may only need to cover distances of less than 1km before final breakout to the subscribers. Distribution cabling will generally consist of medium-sized fibre counts targeted to serve a specific number of buildings within the FTTH area. In specific solution the distribution cables are the same with the feeder cables expanding the two cabling/ducting solutions into the distribution network.

2.5. Drop Manhole (Second Concentration Point-SCP)

In certain cases, the fibres may need to be broken down at a second fibre concentration point within the FTTx network before final connection to the subscriber. As with the FCP, this second point also needs to be a point of flexibility allowing fast connection and re-configuration of the fibre circuits to the final subscriber drop cables. This is termed the SCP. The SCP is positioned at an optimum or strategic point within the FTTH enabling the drop cabling to be split out as close as possible to the majority of subscribers. The location of the SCP may be also determined by other factors such as position of ducts, tubing and access points. Distribution cable fibres are broken down at this point and spliced to the individual or fibre pairs (circuits) of the drop cables. In the proposed solutions the SCP is a Manhole (Drop Manhole) which positioned into the geometrical center of four building blocks. The Drop Manhole contains the joint node closures with the cassettes. The size of manholes in which the aforementioned joint node closure will be installed must be in line with the several national construction laws. For the case of our models the drop manholes will have the form of figure 7.


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Fig. 7: Manhole’s blueprint, Type "A" (340x170x283 cm outer)

Regarding the optical access technology, there are two different joint node closures implementations, one for the P2P technology (figure 7) and one for the GPON which contains GPON cassettes with optical power splitters (figure 8). More specifically in the case of P2P technology one microcable of 144f (Fttb) or four microcables of 144f are inserted in one node closure (four node closures in Ftth) which can manage the 144 fibers. In this solution 144 fibers are shared into groups of 12 fibers in order to be installed to each cassette (12 fibers capacity). The same procedure is followed for the case of Ftth architecture by using 4 node closures.

Fig. 8: Cassettes’ architecture (inside joint node closure) for the case of P2P optical access

technology

BPEO3-S3-EVOL-BDP-48slots

Cassette BPEO-K7-N541106a

14 x

1 X 144f

64 X 2f


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Fig. 9: Cassettes’ architecture (inside joint node closure) for the case of GPON optical access

technology

Moreover, in the case of GPON technology one microcable of 24f are inserted in one node closure which contains eight cassettes with 1:32 splitters in each one and additional 18 standard splicing cassettes for 12 f.

BPEO-S3-EVOL-BDP-48slots


8 x Splitter

PLC-132-2R-

00-15-S-0


18x

1 x 24f In Use 16f per Manhole

The same 1 x 24f The rest 8f are installed (8 f remain dark)

1 x 24f The first 8f are installed

BPEO-S3-EVOL-BDP-48slots

Cassette BPEO-K7- N541104a

8 x Splitter

PLC-132-2R-

00-15-S-0

Cassette BPEO -K7-N541106a

18x

32x 8f

32x 8f


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The spare fibers (from the distribution cable) come out from the node and get in to a second identical closure node. Both nodes have 32 outputs of 8f each one (in total 64 drops of 8 f).

2.6. Drop Cabling

The drop cabling forms the final external link to the subscriber and runs from the SCP to the subscriber building with a distance restricted to less than 500 meters and often much less for high density areas. The drop cables will contain only 1 or 2 fibres for the connecting circuitry and possibly additional fibres for backup or for other network architecture reasons. The drop cable will normally provide the only link to the subscriber, with no network diversity. For underground networks the drop cabling may be deployed within small ducts, within microducts or by direct burial to achieve a single dig and install solution. . The solution which has been chosen makes use of microcables which can carry up to 24 fibers each (Figure 9). These cables are blown into the already installed into the trenches multiducts. The size of multiducts that have been chosen is (8mm/6mm).

Fig. 10: Drop microcable (2-24 f) installed into drop multiduct

Furthermore, it will be necessary the use of cable distributors in order to distribute the fiber cables to the several homes/buildings. For that reason the use of a distributor such as a Y-Branch or Tube Distributor Closures (TDC) seems to be crucial for the efficient management of the drop cabling. The Y-branches/TDCs must be installed into a small handhole in order to be protected and to be accessible from the network provider simultaneously. The size of Y-branches/TDCs handholes must be also in line with the several national construction laws.

Fig. 11: TDC Schematic

Fig. 12: Y-Branch Schematic

6mm

8mm

Multiduct 8/6

Microcable 2-24f


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2.7. Drop Cabling Management

The drop cabling management procedure, which has been followed for the drop cables’ distribution, has been extracted after a case study. In this study several cabling topologies have been studied, taking into account the position of the drop manhole/handhole and the position of the several cable distributors (e.g. Y-branches). The better solution seems (Figure 13) to be a symmetrical topology, in which the manhole is placed on the geometrical center of the drop network and the cables follow the standardized cable’s granularity. The procedure can be described as follows:

If we consider the case that there are twelve houses in one side of the road then a MD(12) (a multiduct with 12 microducts) will be used. When the duct reaches the first house then it will be spliced into a MD(7) (the next multiduct size) and five single ducts (through TDC or Y-branch). The five single ducts will connect with the first five houses and the MD(7) will follow them into the same trench. After connecting the fifth home the MD(7) will be spliced into a MD(4) and 3 single ducts through a Y-Branch. These three ducts will be connected with the next three homes and the MD(4) will follow their route (inside the same trench) until the three cables will be connected with the corresponding three homes. Finally at this point of the trench the MD(4) will be spliced into four single ducts in order to be connected with the four last homes.

Fig. 13: Drop Cabling Distribution

2.8. Building Termination

In the Drop Network, the fiber cable is connecting the Drop Handhole with the buildings of subscribers. The cable will terminate via the multiduct installed in the trenches, inside the buildings (generally in the ground floor) at the termination box.

Fig. 14: Indoor building termination

12 12 9 6

HH 1 1 9 6


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The Buildings contains 1 lower ground floor (termination box placement) and 7 floors with 1 apartment in each floor.

The type of the fiber cable and the termination box depends on the Network Architecture. More specifically:

Network

Architecture

Fiber Cable

terminated in

the Building

Termination

Box in the

Building

Notes

FTTh 8 F.O ODF (8 up to 24 adaptors)

Microcable for each

apartment.

FTTb 2 F.O Termination Box 2-4 adaptors

Microcable for each Building

GPON FTTh 8 F.O ODF

(8 adaptors)

Microcable for each

apartment.

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Documents

ftth network

network builder

network owners

fttx networks

plan fttx technical

fibre infrastructure

required network architecture

design deployment solution