RFS RADIAFLEX® Radiating Cable Helps Provide Seamless Wireless Connectivity to Millions of Boston’s MBTA Subway Riders

One of the primary challenges in designing a solution to offer comprehensive wireless access within the Boston subway system was addressing the city’s highly complex system of underground and underwater tunnels. RFS RADIAFLEX® radiating cable was the key to achieving unparalleled technical performance and reliability.

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RFS RADIAFLEX® Radiating Cable Helps Provide Seamless Wireless Connectivity to Millions of Boston’s MBTA Subway Riders

The Challenge

During the initial phases of the MBTAproject, which included eight platforms infour stations all relatively close to eachother (¼ mile apart or less, with relativelystraight paths), InSite was able to useantennas to provide wireless connectivity.But as the job progressed, theenvironment began to include morecomplex environments such as narrowtunnels, long curves, up and down hillareas, sections of track under bodies ofwater, and more.

Given the nature of the DAS business, you don’t want to have to worry aboutthe technology in place, so it is critical to have goodcomponents and goodvendors…

Additionally, there were instances wherespace to mount the equipment was notavailable and/or there was limited signalpropagation. InSite had also reached apoint where it had to work around themassive flood gates on one of thesystem’s Red Line routes. These gates arelarge doors that allow the tunnels to besealed to prevent water passage duringthe construction of highway tunnels.

With all of these factors in play, antennaswere no longer a viable option.

The rapid growth of wireless communications has resulted intoday’s transit passengers demanding a seamless wireless experiencefor the duration of their commutes. For Boston’s subway riders, this

quality user experience includes being able to use their wireless devices withinthe city’s highly complex system of underground and underwater tunnels.However, the in-tunnel environment is one of the world’s most challengingfrom an RF perspective. The twists, turns and constrained cross-sections ofany tunnel, coupled with the large -- and fast-moving -- vehicles it carries,present an onerous RF distribution challenge. Furthermore, the modernwireless communications systems that serve transit passengers must alsosimultaneously accommodate a wide variety of commercial technologies from 2G to 3G, 4G and beyond.

As a result of this growing trend, The Massachusetts Bay TransportationAuthority (MBTA), the public transportation system of Greater Boston,initiated a project to provide continuous, end�to�end wireless coverage in theunderground stations and tunnels of its transit system. After a public biddingprocess, the MBTA awarded a contract to provide and operate a neutralhost wireless distributed antenna system (DAS) in the subway systemto InSite Wireless, a company focused on the design, construction, operation,and maintenance of shared wireless infrastructure for complex indoor andoutdoor environments. InSite specializes in neutral host DAS utilized bymultiple carriers, specifically targeted at customers who seek seamless wirelesscoverage in the most challenging of physical environments such as conventioncenters, casinos, airports and transit systems, where either the quality ofwireless signals is impaired by building structures or the signal capacity isinsufficient to meet fluctuating occupancies.

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The Solution

InSite engineers had to design a system toaccommodate the varied geometry of thetunnels and the different types of trainsused on each line, as well as a way to getpast the flood gates without interferingwith their operation. To solve probleminstallation areas, the designers specifiedRADIAFLEX® radiating cable from RFS.RADIAFLEX radiating cables facilitate radiocommunication where the usual free spacepropagation of electromagnetic waves ishampered, undesired or impossible - inenvironments such as tunnels, mines,buildings, and large complexes likeexhibition grounds or airports.

Radiating cable is similar to regularantenna cable, with slots cut into the outerconductor that allow the cable to work likea sprinkler hose and “spray out” low levelsof signal along its entire length. Forexample, a single radiating cable extending1,100-1,500 feet will spread an RF signalout to serve a long curve.

To work around the flood gates, the InSiteteam used existing cable sleeves (used forelectricity wiring and other existing cabling)to thread the RADIAFLEX cable through thegates and into the rest of the tunnel –ensuring seamless wireless service.

Time constraints were also a key issue forthe cable installation process. Due to theMBTA’s schedule, installers are only able towork when trains are not running. Afterthe process of shutting down power, worktrains and other vehicles coming through,the installers get an average of only 2 to2.5 hours per night to work.

In this kind of installation process, hi-railvehicles (trucks fitted with special trainwheels to allow them to drive on thetracks) are used to put hangers on thewall of tunnels, which tend to becrowded, so installers have to beextremely careful about where to locatethem. RFS RADIAFLEX cables includenumerous features to simplify installation.To help installers find the correct position,for example, the RADIAFLEX cable jacketis equipped with two guides that fitexactly into the rear open part of RFSstandard clic clamps or in the open slotsof heavy-duty clamps. This simplificationcan be critical under tight timeconstraints.

Furthermore, the highest risk formalfunction, besides cable handling, ispoor installation of connectors. RFS one-piece connectors for radiating cable arevirtually foolproof, further simplifying theinstallation process. RFS also offers a widerange of standard and special drums inorder to meet specific project needs.

We have foundRADIAFLEX® to be atechnically superior cable, and the quality of productand ease of installation havebeen critical factors in oursuccess

Joe MullinVice President of Engineering and

Operations at InSite Wireless

Installers had to work around the massive flood gates,which allow the tunnels to be sealed to prevent waterpassage during construction of highway tunnels. Exist-ing cable sleeves were used to thread RADIAFLEX cablethrough the gates and into the rest of the tunnel.

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There have been numerous challengesbrought on by the rapid growth inwireless usage, and the resultingintroduction of new frequency bands.Whereas connectivity needs were onceadequately served at 800 MHz andbelow, technology systems now have toaddress a wide variety of frequenciesranging from 700MHz up to 2700 MHz.

In designing a systemsuch as the MBTA neutralhost DAS, it is critical to finda cable that will serve all ofthe relevant frequencyranges efficiently.RADIAFLEX had the peakperformance we needed,while covering all of therequired frequencies.

Furthermore, InSite required a radiatingcable solution without stop bands toaccommodate a high-performance,future-proof design for the MBTA DASinstallation. RFS is the only company onthe market with the intellectual propertyand leading-edge technology to suppressstop bands in radiating cables.

The RADIAFLEX suite of radiating cablesfeature RFS’ patented “higher ordermode suppression technique” thatallows RFS to offer cables that supportcurrent and future in-tunnel and in-building commercial and private radioservices from 698 MHz to 2700 MHz forvaluable cost savings. As a result of thispatented higher mode suppression,selected RADIAFLEX cables have no stopband from 698-2700 MHz. RADIAFLEXcables are future-proof with respect toRF spectrum re-banding / re-farming,ensure low insertion loss and excellentcoupling performance, and featurehalogen-free, non-corrosive, low-smokeand flame-retardant jacket material forsafe and reliable long-term cableoperation.

There are a number ofcable manufacturers; thechallenge is finding one thatoffers consistent technicalperformance and reliability,while also providing aneconomical solution. RFS excelled in all of theseareas.

RFS RADIAFLEX® Radiating Cable Helps Provide Seamless Wireless Connectivityto Millions of Boston’s MBTA Subway Riders

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Designing a DAS with Unparalleled Technical Performance and Reliability – Now and Into the Future

The periodic repetition of the slot or slot group causesresonances and harmonics

RFS patented higher mode suppre ssion with no stop bands

The theory behind RFS’ higher order mode suppressiontechnique

A single slot or a groupof slots

Is replaced by 2 slots atspecific distance

Each slot is again replaced by2 slots at specific distance

RFS Patented higher modesupression

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RADIAFLEX cables include numerous features to simplify installation. Cable jackets are equippedwith two guides that fit exactly into the rear open part of RFS standard clic clamps, or in theopen slots of heavy-duty clamps, and RFS one-piece connectors for radiating cable are virtuallyfoolproof.

About InSite Wireless

InSite Wireless specializes in the design, installation, operation, and maintenance of shared wireless infrastructure solutions thatenhance the quality and capacity of wireless voice and data services in public facilities and complex environments. InSite built andlaunched its first DAS at the Moscone Center in San Francisco in 2001, and has developed and currently operates additional projectsin convention centers (including the Boston Convention and Exhibit Center), casinos, airports, sports stadiums, and transit systemslike the MBTA subway system. InSite’s parent company, InSite Wireless Group, LLC, also owns InSite Towers, LLC, which develops,manages, and owns nearly 600 telecommunications towers and sites for wireless carriers.

Conclusion

To date, InSite Wireless has used close to 30,000 feet ofRADIAFLEX cable for the MBTA project, with plans to useapproximately 30,000 feet more in the project’s final phaseof completion. Upon its anticipated 2012 completion, theMBTA installation will be the first neutral host DAS offeringend-to-end coverage throughout the entire subway —including 35 underground stations and 19 miles ofconnecting tunnels.

T-Mobile currently provides 13 miles ofcoverage to 26 underground stops on theMBTA subway line. As a result, ourcustomers are now able to carry onconversations, text and use the Web whiletraveling underground in Boston asseamlessly as they are able to above ground,with no interruption to their wireless service.Ensuring this quality user experience for ourcustomers is critical, and it would not bepossible without the technologicallyadvanced DAS system installed within theMBTA subway system.

Tom EllefsonNortheast Vice President of

Engineering at T-Mobile

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Radio Frequency Systems (RFS)is a global designer andmanufacturer of cable, antennaand tower systems, plus activeand passive RF conditioningmodules, providing total-package solutions for wirelessoutdoor and indoorinfrastructure.

RFS serves OEMs, distributors,system integrators, operatorsand installers in the broadcast,wireless communications, land-mobile and microwave marketsectors. As an ISO compliantorganization with manufacturingand customer service facilitiesthat span the globe, RFS offerscutting-edge engineeringcapabilities, superior fieldsupport and innovative productdesign. RFS is a leader inwireless infrastructure.

For over 35 years, RFS hasprovided total-turnkey RFsolutions for the world’s metros,railway and road tunnels. RFS isthe globally acknowledgedexpert in tunnel RF coveragesystems, with worldwideexperience and know-howspanning six continents andmany hundreds of installations.

Serious about services

Customers know they can count on RFS for comprehensive logistical capabilities,flawless execution and outstanding technicalskills and support. The company’s dedicatedshipment coordinators, hotline staff and on-site engineers go well beyond meretechnology, striving to offer tailored solutions to meet even the most complexsite-engineering and delivery challenges.

RFS’ value-added services match the exact needs of business partners large and small.

Ever-present qualityguarantee

From design to manufacture, ISO 9001 andISO 14001 certification standards encompassall aspects of RFS’ business worldwide. Everyproduct RFS ships has stood up to the moststringent technical, environmental andquality control tests, continuously meetingand surpassing the expectations of a long listof wireless carriers, transportation and utilityoperators, and broadcasters.

RFS backs every product bearing its namewith a quality guarantee that is unrivaled inthe market.

A tradition of innovation

For over a century, RFS has been at theforefront of the wireless communicationindustry through its unwavering commitmentto design and develop the world’s mostadvanced technology in the field. DedicatedR&D teams, along with a privilegedpartnership with Bell Labs, are at the source ofbreakthroughs that are ensuring the mobilityof an increasingly wireless world.

RFS is at the frontier of wireless technologyinnovation, sustaining the boldest ventures toenhance the way people communicate and live.

A truly global company

With on-the-ground personnel in more than 20 countries and on every continent,RFS always delivers on its commitments,providing a comprehensive range ofpremium products, systems and services. Its clients benefit from all the advantages ofa global supplier, while relying on dedicatedsupport from RFS’ local engineering,manufacturing and shipping teams.

RFS’ products, systems and personnel can befound in every corner of the planet.As a global group, RFS is committed toupholding the most stringent environmental,health and safety standards, and seeks tointegrate green initiatives in every aspect ofits business.

Why RFS?

T h e C l e a r C h o i c e ®

www.rfsworld.com

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