1511 BA

Voice telephony is still the major revenue generator formany service providers. Rural access for POTS, ISDNand data (RAPID) proves to be effective and cost efficientin scarcely populated regions, and is therefore comple-mentary to other rural access technologies such as fixedwireless access, fixed cellular, satellite and new wirelessaccess technologies, such as WiFi and WiMAX.

It allows service providers to maximize revenues, and at the same time control costs of network deployment, while increasing teledensity in rural areas. Its compactnessenables fast deployment that allows service providers to offer services and ensure minimized payback time in rural areas with low average revenue per user.

In addition to voice communications, RAPID also supportsdata and Ethernet access, hence helping to bridge thedigital divide by increasing the availability of access to communication resources.

White Paper

RAPIDEnabling Access for Rural Communities with the Alcatel 1511 BA

TABLE OF CONTENTS

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Overview of Connectivity Options . . . . . . . . . . . . . . . . . . . . . 2

V5.2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Subscriber Emulation-Based CAS Signaling . . . . . . . . . . . . . . . . . . . 3

Mirror-Based Solution for Combined Services . . . . . . . . . . . . . . . . . . 3

About RAPID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Outdoor Cabinet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Remote Multiplexer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Network Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Introduction

Bringing telecommunications facilities and services toscarcely populated areas has always been a costly andtiresome exercise for public network operators. In manycases, the required capital expenditure (CAPEX) toreach and connect remote areas and to provide sufficientprotection for installed equipment against weatherconditions and intrusions does not guarantee a sufficientreturn on investment (ROI). However, as broadbandconnectivity becomes ubiquitous in metropolitan andurban areas, rural residents are becoming less willing toaccept the digital divide. They expect the same access to services and quality of services as those enjoyed inmore densely populated areas. As a result, every publicoperator must provide connectivity upon request, andthe ability to do so is becoming a competitive necessity.

To ease the network operator’s task of helping ruralcommunities bridge the digital divide, Alcatel hasdeveloped the Rural Access for POTS, ISDN and Data(RAPID) solution, based primarily on the Alcatel 1511 2 Mb/s Multiservice Business Access Multiplexer (BA).The RAPID solution supports a range of servicesappropriate for rural communities:> POTS> ISDN> Low speed data (asynchronous) up to 64 kb/s> High speed data at N x 64 kb/s (N = 1 to 31)> Ethernet at N x 64 kb/s (N = 1 to 31)

With the following characteristics, RAPID is designed toaddress the specific requirements of operators providingsolutions in rural areas:> Flexible enough to address very small configurations

(up to 30 64 kb/s payload channels)> E1-based, with optionally a built-in single-line high-

bit-rate digital subscriber line (SHDSL) transmissionbooster or an optical E2

> Available as an indoor unit, or a robust pole or mast-mounted outdoor cabinet

> Single phase AC fed with a built-in battery back-up of eight hours

> Separate equipment and distribution bay> Low cost solution resulting in fast ROI> Local and remote management capabilities> Plug-and-play concept making use of pre-cabled,

pre-programmed standard models> Does not require changes to the existing installed

base (i.e., the exchange)> Operates under extreme climate conditions

RAPID: Enabling Access for Rural Communities with the Alcatel 1511 BA

A L C AT E L > 1

Figure 1 - RAPID Installation in Africa

Data(LAN)

Copper SHDSL

Optical Fiber

E1s

Data

ISDN S

POTS

Fax

DataNetwork

VillagePhone

Data(LAN)

Data

ISDN S

POTS

Fax

µWaveCo-located

1515 CX-C

1511 BA

RAPID

1511 BA

RAPID

1511 BA

RAPID

1511 BA

DataISDN SPOTSFax

Figure 2 - RAPID Deployed in Telecom Infrastructure


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As depicted in Figure 2, the RAPID solution can bedeployed alongside operators’ synchronous digitalhierarchy (SDH)/dense wavelength division multiplexing(DWDM) and microwave or GSM tower infrastructures as well as the infrastructures of power utilities, or railwaycorporations, for example. This enables operators toleverage the existing infrastructure of other organizations.At an operator central office site, the solution connectsvia different options to an existing local exchange.

Overview of Connectivity Options

This section describes network scenarios in which theAlcatel RAPID solution is used as an access medium tothe subscriber. Three connectivity options are available: > V5.2 connection at the exchange> V5.1-based subscriber emulation> Mirror-based solution for combined services

V5.2One V5.2 interface from the exchange is sent to a con-verter. The converter provides the necessary signalinginformation towards the multiplexer. Up to 24 multiplexersthen provide connectivity for up to 720 subscribers. Thissetup guarantees a more than decent 0.12 Erlang (thenumber of call seconds per hour) per subscriber.

Figure 3 - V5.2 Connectivity Option

30 Subscribers

V5.2 Interface (4 E1)

24 E1s with CAS

30 SubscribersExchange V5.2 to

CAS Converter

1511 BA

RAPID (1)1511 BA

RAPID (24)

The major strengths of the V5.2 connectivity option are:> V5.2 is an open interface that can be connected to

any digital exchange> No upgrades are required to existing exchange

equipment> Only limited investment is required at the exchange

end (addition of a converter box, which can serve up to 24 remote sites)

This solution is most economical for a volume of 400subscribers or more, connected to a single exchange.

SUBSCRIBER EMULATION-BASED CAS SIGNALINGThis connectivity option is appropriate when networkoperators want to provide only voice services. In thisscenario, the RAPID is connected directly to the exchangevia a 2 Mb/s link. The protocol will be a channel associatedsignaling (CAS) signal with subscriber emulation embed-ded in the exchange. This option has two significantcharacteristics:> Line signaling is based on the CAS protocol

(recommendation Q.421)> Subscriber processing (providing dial tone, reception

of digits, etc.) is done in the exchange

Up to 30 POTS lines can be installed per RAPID pole-mounted cabinet. An indoor subrack can house 90subscribers. A fully equipped, standard 19 inch racktotals 450 subscribers.

Advantages of the subscriber emulation connectivityoption include:> No investment is needed at the exchange > It is extremely well suited for a low volume of

subscribers (less than 50) added to a single exchange

This solution is, however, proprietary and supported by only a limited number of exchanges.

MIRROR-BASED SOLUTION FOR COMBINED SERVICESWhen transporting different services (i.e., services withspecific signaling requirements), network operators cannotmake use of a standardized signaling protocol like V5.2,which allows them to connect a hybrid trunk directly toan exchange. To overcome this inconvenience and enablemultiple services for rural users, an additional buildingblock is introduced into the network topology. A smallcross-connect (Alcatel 1515 Compact 1-0 Digital Cross-Connect [CX-C]) acts as a groomer between the exchange,the data network and the RAPIDs in the network.

As inputs, the cross-connect can receive:> E1s carrying up to 30 POTS channels> Full E1s carrying 64 kb/s data channels> Single basic access lines (a,b wired) in a mirror

configuration with the switch

At the output side, each RAPID is connected to thecross-connect by an E1. The network will use proprietarysignaling because this E1 contains a mix of POTS, basicrate access (BRA) and data channels.

With this setup, the operator can serve up to 480 userchannels. In theory, 16 RAPIDs can be connected to onecross-connect, if each RAPID is equipped to its maximum.In practice, with an average filling of 75 percent, up to 20 RAPIDs can be connected to a single cross-connect.The typical equivalents are as follows:> POTS: 1 user channel per subscriber> BRA: 3 user channels per basic access subscriber> Data: 1 user channel per 64 kb/s connection


A L C AT E L > 3

ExchangeRAPID

1511 BA

E1 CAS

1511 BA

RAPID1/0

Cross-connect

E1

VAMData

Network

Figure 5 - Mixed POTS and Data Connectivity Option

Figure 4 - Subscriber Emulation-Based Connectivity Option

About RAPID

The building blocks of the RAPID are:> An outdoor cabinet> A power supply> Alcatel 1511 BA > A main distribution frame

OUTDOOR CABINETThe outdoor cabinet contains all the necessary buildingblocks to serve the rural subscriber (see Figure 6).

Air inlets at the top and bottom of the cabinet allowoutside air to cool the inner wall in a free circulatingmanner. In tropical environments, a fan can be installedto circulate air within the equipment bay and guaranteean equal spread of generated heat. All cables are fed intothe outdoor cabinet from the bottom.

The cabinet’s internal structure consists of theequipment area, the power supply and the distributionframe (see Figure 7).

A door contact and a temperature sensor can be readby the management card. This alarm can be sent to aremote monitoring center.

REMOTE MULTIPLEXERThe Alcatel 1511BA functions as the remote multiplexerin the RAPID solution. It is a nine-slot multiplexer that is only 24 cm wide. The nine slots are filled with:> 1 controller> 1 network management interface board for local and

remote management> 1 DC/DC converter with ringing generator capacity

(redundancy is possible)> 6 universal positions to be used for tributary or

transport boards

APPLICATIONSThe six free slots are used to install tributaries thatsupport various applications. The three applicationsdescribed below are most relevant for rural users andhave, therefore, been selected for RAPID.

POTS: Analog POTS subscribers can be directly connectedvia a/b wires to one or more subscriber interface boards.The granularity can be either five or ten circuits per board.All commonly used impedances are available, coveringline distances from 1 km up to 12 km. Further 12 and 16 KHz metering, reverse battery and country-dependantringing are supported.


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Features> Dimensions: 350 x 810 x 400 (wxhxd)> Weight: approx. 20 kg (fully equipped)> Protected against dust and water penetration (IP 55)> Operates on single phase 240 VAC> Corrugated steel> Equipment bay separate from distribution bay> Two universal clamps to fit any type of pole> Safety locks> Outer and inner cabinet structure for optimal cooling> Fan driven cooling (optional)> Cable throughput by means of swivels> Door contact and temperature sensor for remote monitoring> Fully pre-wired> On site activities limited to power and subscriber conditions

> Two safety locks to secure the equipment bay > can be made customer-dependent (standard key)> Power cabling block for termination of all power cables, such as > equipment > batteries > rectifier > 240VAC> Low voltage disconnect> DC fuses> Equipment area containing a T9 subrack that houses the controllers and the tributary boards that interface to subscribers> Fan unit for even heat distribution> Power compartment housing a 48 Vbackup battery and a 120 W AC/DC rectifier> Distribution area is separate from the equipment area

Figure 6 - The Outdoor Cabinet

Figure 7 - Internal Layout of the Outdoor Cabinet

1 2 3 4 5 6

CNCC

PCM

C2 B

is

RGPA

eoc1eoc2

Figure 8 - Basic Configuration with DC Feeding

ISDN: ISDN subscribers can be directly connected via a/b wires to one or more ISDN-BA U-interface boards.The interface board consists of five ISDN BRA lines. The interface uses the Uk0 Basic Access 2B+D formatwith 2B1Q line coding. This interface requires a mirrorsolution with line terminator (LT) boards at theexchange side and network terminator (NT) boards at the RAPID end.

Local or remote data: Instead of using direct data con-nections, the RAPID solution uses a modem combination,in which the U6VAM tributary acts as a DCE while theversatile access modem (VAM) acts as a DTE. This appli-cation covers a distance of up to 8 km, supports 128 kb/sor 2 x 64 kb/s X.21/V.35 and uses the outside plant wiringthat is already available.

Several other applications can also be deployed usingRAPID, but they are not top candidates for a ruralsolution and are only listed here for completeness. These applications include:> Low speed asynchronous data up to 64 kb/s,

only for local use> 15 kHz audio (with or without E&M)> Hotline facility> 30-party conference bridge> Local battery connection> N x 64 kb/s (N = up to 30)> ISDN So interface> Ethernet N x 64 kb/s (N = up to 30)

NETWORK MANAGEMENTFull remote monitoring and control is essential for a ruralsolution, where equipment will be installed in distant areasto which access can be limited due to road conditions orseasonal disturbances. The RAPID solution incorporatesthree building blocks for remote management:> Element manager: local craft terminal with the Alcatel

1320 NX (NECTAS) software package> Network operations center: Alcatel 1322 VD Mediation

Device with the 1321 NX (NOCTAS) software package > Network manager: Alcatel 1353 AC

Figure 9 shows the virtual position of each of thesebuilding blocks and the respective signals that are being sent.

Together, these network management componentsprovide all the features that are expected from a state-of-the-art management platform. Depending onrequirements, an operator can choose:> An element manager for local maintenance> Network operations managers to maintain and monitor

a limited number of RAPIDs (i.e., connected to thesame exchange)

> A network management platform that controls andmanages the entire network


A L C AT E L > 5

OS: 1353 AC

1321 NXOperation Craft Terminal (OCT)

1320 NXElement CraftTerminal (ECT)

1322 VD

Q3 (X.25/Ethernet)

RS-232

(R)Q2 (R)Q2

RS-232RS-232

Q3 (X.25/Ethernet)

DCN Network

1515 CXC-C

1511 BA

RAPID

Figure 9 - Network Management Overview

Conclusion

The RAPID solution from Alcatel enables networkoperators to address the burgeoning rural communityand remain competitive by bringing premium services to scarcely populated areas. Rural residents can enjoynot only traditional POTS service, but ISDN basic accessand low-speed data over a single 2 Mb/s link.

RAPID is easy to install and robust once in place. It isfed from the commercial power grid with a back-up bat-tery, allowing easy implementation even in areas wherepower outages are frequent. Its robust mechanical designprotects against vandalism, theft and animal attacks. TheIP-55 value of the equipment bay prevents damage fromwater, insects and dust. The Alcatel 1511 BA itself has aproven track record in very harsh environments worldwide.It has been deployed in pipeline, metro and railwayprojects, both indoors and outdoors.

Implementing RAPID does not require a highly skilledworkforce. Operators can take advantage of a comprehen-sive network management system to control, monitor andreconfigure the network from a central network operationscenter. This results in a plug and play operational modethat does not require specialized skills from people in the field.

Ultimately, RAPID provides the ideal answer for con-necting rural areas to the rest of the world and allowingthe local population to enter into and enjoy the benefitsof the 21st century.

ABBREVIATIONSBRA basic rate access (for ISDN)CAPEX capital expendituresCAS channel associated signalingDWDM dense wavelength division multiplexingECT equipment craft terminalIP 55 Indication of degree of protection against

dust and humidityISDN integrated services digital networkLT line terminationNT network terminationOCT office craft terminalOS operating systemPOTS plain old telephone system/serviceRAPID rural access for POTS, ISDN and dataSDH synchronous digital hierarchySHDSL single-line high-bit-rate digital subscriber lineVAM versatile access modem


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Alcatel assumes no responsibility for the accuracy of the information presented, which is subject to change without notice.

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