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DN0745859Issue 1.0

© Nokia Siemens Networks 1 (32)

Nokia Flexi EDGE Base Station

Overview of Feederless SiteSolution



Overview of Feederless Site Solution

2 (32) © Nokia Siemens Networks DN0745859Issue 1.0

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Contents

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Contents

1 About this document .............................................................................5

2 Introduction to Nokia Flexi EDGE BTS Feederless SiteSolution...................................................................................................7

2.1 Feederless Site solution provides several benefits for theoperator....................................................................................................8

3 Optical connection between Flexi EDGE System Moduleand Sector Module ...............................................................................11

3.1 The All-in-one Optical Converter Module (EOCA) and itsconnections............................................................................................12

3.2 Plug-in-Units of EOCA............................................................................14 3.2.1 Optical Interface .....................................................................................14 3.3 Optical connection cable alternatives.....................................................15

4 Configuration examples ......................................................................18

5 Power feed principles and power sources ........................................24 5.1 General power feed principle .................................................................24 5.2 Power Sources for Feederless Site........................................................25 5.2.1 DC feed to remote sectors from centralized DC source.........................25 5.2.2 AC feed to remote Sectors with local AC/DC conversion.......................26

6 Technical specifications for connections to remote sectors...........28





Summary of changes

This is the second issue. Changes compared to first issue:

- Flexi EDGE BTS SW EP1.1 support for EOCA inserted

- OVP always integrated, not a plug in unit any more

- Figures updated with newer pictures

- New 48V DC feed distances vs. cable type, table2 updated



About this document

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1 About this document This document gives an overview of the Nokia Flexi EDGE BTSFeederless Site Solution.

Please refer to Nokia Flexi EDGE BTS Product Description document. Itincludes all information of the Flexi Modules and Flexi EDGE BTS itself.

The document includes information under the following topics:

Nokia Flexi EDGE BTS Feederless Site Solution introduction

Optical cable connection

Power distribution principles

Examples of supported configurations

Solution-specific technical data

Nokia Flexi EDGE BTS Feederless Site is part of Nokia Flexi EDGE BTSapplications.



Introduction to Nokia Flexi EDGE BTS Feederless Site Solution

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2 Introduction to Nokia Flexi EDGE BTSFeederless Site Solution

Nokia Flexi EDGE BTS Feederless Site solution refers to Flexi EDGEmodule constellation where the System Module of the BTS and some, orall the Sectors with their respective RF modules are installed apart from

the System Module.

For connecting the modules together, 2 separate technologies aresupported:

Multi mode technology: main technology for Flexi EDGE FeederlessSite with max 150m distance between System Module and Dual TRX’s(DTRX’s)

Single mode technology: more costly technology providing up to 10kmdistance (to be confirmed in testing) btw modules – this application isreferred to as Distributed BTS.

Basically in both cases above a distributed BTS architecture is deployed;hence in a way the Distributed BTS definition applies to both of them but

in this context the Distributed BTS is used for sites with single-modeoptics. The Feederless Site describes well the site in which traditionallythe BTSs would be connected to antenna with long antenna feedercables degrading the RF performance and site coverage considerably.With the Feederless Site solution, instead of use of antenna feeders afibre is laid and no compromises with the site coverage need to bemade. It is assumed that the Feederless Site case is the main use casefor the distributed architecture.

In Feederless Site application, the distance between System moduleand remote sector can vary from few tens of meters to up to 150 meters,maximum distance dictated by the date rate in the fibre. The multimodeoptical fibre connects System Module to DTRXs via optical converters.

Power distribution to Remote Sectors can be provided either as DC or AC voltage. When DC is fed to Remote Sectors from centralised DCbattery system residing close to the System module, the maximumdistance between batteries and DTRX modules is 100 m.





As mentioned above, longer distances than the 150m are also possiblehowever they require single mode optical technology (fibre and opticaltransceiver) and separate power supply scheme (typically local AC) forthe remote sectors.

Feederless Site solution will be commonly used e.g. on a rooftop BTSsite as show in figure 1 or in a mast top application as in figure 2. Inthese applications it’s beneficial to employ Feederless Site solution andinstall Flexi EDGE DTRXs / Sector Module very close to antennabecause then the connections to an antenna can be made with a short jumper cable with maximal RF performance and minimised costs.

Figure 1. Example of Nokia Flexi EDGE BTS Feederless Site solution

2.1 Feederless Site solution provides several benefitsfor the operator

Improved RF-Performance with Feederless Site compared to traditionalBTS Site:

• Better overall Site RF performance compared to traditionalinstallation



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− 2…5 dB better downlink performance compared to typicalinstallation with 30…80 meter long antenna feeders

− In case Mast Head Amplifiers are not preferred, also uplinkwill improve – as the RF feeders and their losses are

dismissed

− Better RF performance yields in increased voice quality,improved coverage especially indoors, and higher datathroughput

Total Cost of Ownership is remarkably lower because:

• Lower number of Sites

• Material savings

− No need for Mast Head Amplifiers

− No feeders needed between BTS and antennas• Installation savings

− Cheaper materials compared to Feeders

− Easier installation because lighter materials

− Cheaper tool investments

Open new installation possibilities especially with difficult places

• Existing buildings can be used without expensive strengthening ofthe structures as the module weight can be distributed

• Unique solution available only from Nokia Siemens Networks

Enabler for Distributed BTS solution with module distances of severalkm’s

• The Feederless concept can be adapted to Distributed BTSapplication by deploying different optical components. This way thedistance btw System module and RF-modules can be extended toseveral kilometres. Due to distance, power feed for the remotemodules needs to be provided locally e.g. with the help of AC/DCmodule.

Apart from the Rooftop (Figure 1), another application for FlexiFeederless Site concept is on coverage sites, for which tower and mastinstallations become feasible with the Feederless concept. In this case





RF Module is installed to the top of mast and System Module installedon ground level e.g. in battery cabinet attached to the mast.

Figure 2. Example of Nokia Flexi BTS Feederless Site mast installation.

The excellent reliability of the Flexi EDGE modules with the non-existingneed for regular maintenance will ensure that modules need to be visitedonly rarely. The most stringent testing has been performed so that theunits are able to withstand the stress at open-air environments, andeven at mast-tops.

Naturally another approach to mast-top installations, in which theFeederless Site concept is not used, is when the System Module isplaced at the mast-top together with the System Module. The BTS localmanagement can take place by connecting the PC to optional O&Mcable installed to run from the System Module down to ground level.

2+2+2 DTRX & Optical

Converter (Mast Top)

System Module, External Alarms,

Optical Converter

Power system (Mast Base)



Optical connection between Flexi EDGE System Module and Sector Module

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3 Optical connection between Flexi EDGESystem Module and Sector Module

Nokia Flexi EDGE Feederless site is based on the new, all-in-one

Optical Converter hardware sales item (EOCA). For creating an opticallink between the System Module and the Remote modules, a pair ofconverters needs to be deployed, one in both ends of the fibre link. Thisway the Gigabit Ethernet - Optics conversions take place as needed. Tominimise system impact, the conversions occur transparently for theBTS. BTS SW EP1.1 BTS SW supports fully the use of EOCA opticalconverters.

Figure 3. Optical connection carries the data and synchronizationinformation





Apart from the optical converter itself, the fibre and DC feeder runs toremote sectors, no other Feederless Site –specific hardware items areneeded. The optical converter and range of suitable IP protected cablesare supplied by Nokia. The system has been designed for standard DCcable types hence DC cable is assumed to be sourced locally at thecountry of destination.

3.1 The All-in-one Optical Converter Module (EOCA)and its connections

The optical converter is the key component for the Feederless Sitesolution. It is designed by Nokia Siemens Networks with specific circuitryinside, conveying not only the end-user and system data, but also theneeded synchronization and clock signals to remote DTRXs.

Key features and functionality of Optical Converter Module (EOCA)

• Conversion between Gigabit Ethernet and Optics for 3 DTRXs

• Maintaining synchronisation between System Module and RemoteDTRXs

− Extracting synchronisation information (FCLK, FN) from theGb Ethernet at local converter

− Multiplexing the synchronisation info into fibre

− Recreating the synchronisation clocks at the remote end andfeeding them to remote DTRXs via Gb Ethernet connection

• Multiplexing and conveying user data, alarms and synchronisationdata for 3 DTRXs via single optical fibre

• Integrated Over Voltage Protection for DC feeder in both ends ofthe link

• Support for remote DTRX shut-down feature during low-traffichours

• Transparent operation between System Module and remote DTRXmodules without BTS software and System impacts – full supportof all BTS features in EP1.1 BTS SW onwards (except RTCcombiners not supported) without performance degradation

• Full compliance for all Flexi installation options with sameenvironmental performance as with other Flexi EDGE modules(operational temperature range, IP rating, etc.)

One optical link with a single converter pair connects to up to threeDTRX’s, The DTRX’s at the remote end can be configured freely, either




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to a single sector or into separate sectors. The multiplexing functionalityimplemented in the optical converter reduces the number of fibresbetween System and Remote modules so that only one fibre is neededfor connecting to 3rd DTRX in a sector.

The front panel of the EOCA contains BUS interface connections(Ethernet + synchronization) and 48VDC interfaces for two DTRXs (2nd and 3rd DTRX). The connections for the 1st DTRX are made with so-called pigtail cables (cables pre-inserted in the EOCA) exiting themodule from the back (see fig. 4). In addition to these, the front panel ofthe converter module provides a plug-in optical interface slot, 48V inputterminals (bolts), led’s for status indication and a plug-in OVP moduleslot.

Figure 4. Optical converter interfaces

Depending on the location of the optical converter, the converter is

connected either to DTRX/s (remote end) or to the System Module (localend). The pigtail cables will be used in both ends to make the Ethernetand power connections for the 1st DTRX. The rest of the connectionswill be made through the cables provided with DTRXs except oneadditional Ethernet cable (EECA) needs to be deployed with the 3rdDTRX.

The advanced functionality of the Flexi EDGE BTS includes remote-controlled switches for shut-down of the DTRXs during low-trafficperiods. This functionality is supported also by the optical converters.The optical link will convey the status of DTRX power condition to theother converter at the remote end, which will then power down the48VDC from the respective DTRX.

two buses optical, two powers, DC-input

Pre installed power and GbEthernet bus cables on back





3.2 Plug-in-Units of EOCA

3.2.1 Optical Interface

The technology utilised for the optical interface is the same deployed inNokia Flexi WCDMA BTS. The solution hence uses SFP (Small Formfactor Pluggable) optical transceivers.

SFP transceivers are available with a variety of different transmitter andreceiver types, allowing users to select the appropriate transceiver foreach link to provide the required optical reach over the available opticalfibre type (e.g. multi-mode fibre or single-mode fibre). The standard FlexiEDGE Feederless Site interface is based on use of 850nm multimodelaser transceivers (provided with EOCA) and related 50µm multimodefibres. The date rate in the optical link will set the maximum distancebetween two modules to 150m.

As mentioned earlier, the module-to-module distance can be extendedwith single-mode technology to up to 10 kilometres (to be confirmed intesting before commercial availability of the converters). The SFP typeand fibre in this application will be different, and they need to be orderedseparately.

Figure 5. SFP, Small Form factor Pluggable optical transceiver.




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3.3 Optical connection cable alternatives

The optical cable type in Flexi EDGE Feederless site is multimode 50µmfibre. The Nokia supplied cables (FSFB 50meters, FSFC 100m) areprovided with pre-installed IP sealed connectors.

Figure 6. Nokia optical 50 m multimode cable (FSFB) with IP55 sealing

When the desired distance is higher than 100m, a Multimode adapter(comes as part of the FSFC cable kit) can be deployed. For maintainingIP protection for the cable, the joint made with the adapter should beplaced inside Nokia Flexi System External OVP device IP55 box(FSEC), or any other IP sealed box sourced locally.





Figure 7. Optical cable extension to 150m

Shortening the ready made cables is possible, using the same principle

above and maintaining the IP sealed connectors in the ends of the fibre.




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4 Configuration examples The Flexi EDGE Feederless Site solution has been designed so that theflexibility in terms of configurations and installation options is retained. Agood example of this flexibility is depicted in the figure below where themast-top configuration is expanded with a parallel converterpair/fibre/DC feed installation and extension DTRX’s. This exampleshows that the optical extension does not limit the site expansion forFuture traffic growth.

Figure 8. Mast-top installation with expansion 2+2+2 => 4+4+4



Configuration examples

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In the next figure, a module constellation in a Rooftop application isshown. This example demonstrates also the system flexibility as itshows that both remote sectors and local sectors can be connected to

same System Module forming a single BTS entity.

Figure 9. Rooftop application 6+6+6

Next figures illustrate how the remote sector could look like whendeployed in stack. They also demonstrate the unparalleled expandabilityand high RF performance of the Flexi EDGE Feederless Site. Thanks toslim form of the Optical Converter, it can be placed in the same casingwith a DTRX.





Figure 10. Remote sector expansion in stack

The optical converter can be installed in casings, either alone or with

another optical converter, or as shown in figure 11, into shared casingwith a DTRX. Naturally the converter (19” wide) can be installed into 19”rack/cabinet as well.

Figure 11 High RF performance of Flexi platform is also available in FeederlessSite installations. Note plinth included in Height Units.

2TRX 4TRX 6TRX 8TRX

1 Optical Converter 2 Optical Converters




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Figure 12 Expandability of Flexi EDGE platform allows for capacity growth withhigh performance and no impacts in antenna. Note plinthincluded in Height Units.





Figure 13. Capacity expansion with boosted cell coverage.

As demonstrated in the above figures, the design of the Flexi EDGEFeederless Site solution is providing the same high RF performance atremote sector sites as is provided in standard Flexi EDGE BTSinstallations. The use of standard high performance Flexi EDGE DTRXsin Feederless Site applications ensure sufficient carrier power evenwhen sector expansions take place, typically this would mean that nocoverage loss is to be expected (assume cell to be uplink limited with2TRXs).

The Feederless Site solution is available for all the standard Flexi EDGEconfigurations, except not for RTC (Remote Tuneable Cavity Combiner)applications. This is due to the related complexity in fitting the separateRTC-System module bus into the optical link.




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5 Power feed principles and powersources

5.1 General power feed principle

The power feed at Flexi EDGE Feederless Site is provided eitherthrough Nokia supplied power system or with 3rd party products.

The input for the System Module and to the Optical converters directly isstandard -48 VDC with positive earth. System module will distribute -48VDC further to local sector/s and optical converters will take care ofthe power distribution for the remote sector/s.

Figure 14. Power feed scheme for local and remote sectors

The DC feeder cable to remote sectors is of standard 16mm2 to 35mm2DC cable type and as such is planned to be sourced locally. DC feeder



Power feed principles and power sources

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cable with a jacket and grounding kit is recommended. The DC cablethickness varies based on cable length and number of DTRXs (see tablein chapter 6).

When calculating the site power consumption and related battery back-

up times, the losses in the DC feeders and the EOCA’s need to beconsidered. The EOCA power consumption will be 20W. The power lossexperienced within the DC feeder depends on the feeder type andlength, as well as from the applied DC voltage.

5.2 Power Sources for Feederless Site

There are two basic approaches in the supply power schemes for theFlexi Feederless Site and its modules. These approaches are describedin the next two paragraphs.

5.2.1 DC feed to remote sectors from centralized DC source

This is the most common DC scheme, deployed to provide long back-uptimes (typically hours) for the BTS and its modules, both at local as wellas in remote end/s. Depending on the level of BTS-battery integration,two distinct ways of building the site can be found:

• Conventional stand-alone battery back-up system located close toSystem Module providing DC power for the local DTRX’s viaSystem Module and remote DTRX’s through DC feeder/s

• A modular Battery Back-Up system integrated into the BTS cabinetwith the System Module and local sectors. A typical solution likethis is the Nokia MIBBU with optional outdoor Flexi Site SupportModule (FCSA), batteries and Flexi Outdoor Cabinet (FCOA)





Figure 15. DC power feed scheme.

5.2.2 AC feed to remote Sectors with local AC/DC conversion

In this scenario, the remote sectors are powered locally. The reasons fordeploying AC feed to remote sector are several:

• Power supply equipment is distributed enabling use of smaller andlighter AC/DC modules with integrated batteries. This way theheavy centralized battery systems can be avoided, and all the siteequipment can be hand-carried to site

• The distance btw System Module and remote sectors can beextended to 150m, or alternatively, with the Single-modetechnology, the distance can be extended to several kilometres.

The main component utilized with AC fed systems in the Nokia FlexiPower Module (FPMA) with integrated AC/DC rectifiers and optionalshort-term (minute-level) battery back-up. The FPMA can be equippedwith various combinations of rectifiers and battery blocks depending onthe need.



Power feed principles and power sources

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An OVP protection device is needed for AC feed to AC/DC Powermodule when AC feeder cable is susceptible to lightning e.g. in mast-topinstallation.

Figure 16. AC power feed

The Lithium-ion batteries used in Nokia AC/DC Power Module ensure relatively long

back-up time despite of their small size, e.g. 15-25mins for the remote sector in the

Figure 14. With larger configurations, the Intelligent Power Shutdown feature can

be used to power down part of the DTRXs to extend the duration of the back-up

time.

The use of AC for powering the BTS enables full distribution of the BTS with all the

benefits of Flexi concept retained:

• No cabinets as batteries distributed – widest variety of site optionsavailable

• Easy site building, easy module transportation

• Maintenance-free site; no regular visits for battery replacement





6 Technical specifications forconnections to remote sectors

Please refer to main Nokia Flexi EDGE BTS Product Overviewdocument for general information on Flexi BTS. It includes all thegeneric technical information of the Flexi Modules and Flexi EDGE BTS

itself.

Table 1. Requirements for shielded locally-sourced DC cable

DC cable requirements

Resistance < 1ohm / km

Inductance < 0,3 mH / km

Length Max. 100 meters between DC supply and Nokia Flexi EDGE

DTRX

Diameter Min. x 16 mm2 twisted

Shielding Min. 16 mm2



Technical specifications for connections to remote sectors

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Table 2 Maximum DC feed distance for feeding 3 DTRXs via single DC feeders (function ofcable thickness and minimum BTS input voltage)

Min ESMA Input

voltage/VDC

16 mm2 25 mm2 35 mm2

42 21 m 33 m 46 m

44 48 m 77 m 100 m

46 76 m 100 m 100 m

What can be noticed from the table 2 is that the higher the input voltage in the BTS is, the

more voltage loss can be tolerated in the DC feed cable, and consequently thinner cablecan reach longer distances

Table 3. Requirements for Multimode Optical Interface

Optical interface

Nokia IP55

cable length

50 or 100 meters (FSFB 50m, FSFC 100m)

Two cables can be connected to 150 meters

LC duplex

optical

connector ANSI TIA/EIA604-10 (FOCIOUS10)

Conventional

OM2 duplex

multimode

fibre,

Connection to

SFP module

(ISO-11801), ITU G.651

- OFL BW 500 MHz*km

- 50/125 um (core/cladding diameter)

Allowed

attenuationApprox. 0.75 dB / connection

Operatingtemperature

-40 …+85 °C

Weather

protectionMin. IP55



Glossary

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Glossary

AC Alternating CurrentBTS Base StationDC Direct Current

DTRX Dual Transceiver ModuleFCSA Optional Flexi Cabinet Site support moduleFPMA Optional Flexi Power ModuleFPAA Optional Flexi Power AC/DC sub-module 230 V for FPMAFPBA Optional Flexi Power Battery sub-module for FPMAFSFB Flexi System Fibre B, length 50 mFSFC Flexi System Fibre C, length 100 mFSEC Optional Flexi System External OVP device IP55 boxHW HardwareIP55 Ingress Protection class for outdoor equipmentLTE Line Terminal Equipment (space) in FCSAMIBBU Optional indoor Multi Integrated Battery Back-up solution MIBBU = WPU + 1…4

WPM + 62 Ah or 92 Ah batteryOVP Over Voltage Protector for AC and DC power lines

PIU Plug-in-unitSFP Small Form factor Pluggable optical transceiverSW Software

feederless installation

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