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TRANSPORTATION SOLUTIONS

CASE STUDY

RFS RADIAFLEX Radiating Cable Helps Provide®

Seamless Wireless Connectivity to Millions of Boston’sMBTA Subway Riders

One of the primary challenges in designing a solution to offer comprehensive wireless access within the Bostonsubway 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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TRANSPORTATION SOLUTIONS

CASE STUDY

RFS RADIAFLEXRadiating Cable Helps Provide Seamless Wireless®

Connectivity to Millions of Boston’s MBTA Subway Riders

The Challenge

During the initial phases of the MBTA

project, which included eight platforms in

four stations all relatively close to each

other (¼ mile apart or less, with relatively

straight paths), InSite was able to use

antennas to provide wireless connectivity.

But as the job progressed, the

environment began to include more

complex environments such as narrow

tunnels, long curves, up and down hill

areas, sections of track under bodies of

Twater, and more.

he rapid growth of wireless communications has resulted in

Given the nature oftoday’s transit passengers demanding a seamless wireless experience

for the duration of their commutes. For Boston’s subway riders, this the DAS business, you don’tquality user experience includes being able to use their wireless devices within

want to have to worry aboutthe city’s highly complex system of underground and underwater tunnels.

the technology in place,However, the in-tunnel environment is one of the world’s most challenging

so it is critical to have goodfrom an RF perspective. The twists, turns and constrained cross-sections of

any tunnel, coupled with the large -- and fast-moving -- vehicles it carries, components and goodpresent an onerous RF distribution challenge. Furthermore, the modern

vendors…wireless communications systems that serve transit passengers must also

simultaneously accommodate a wide variety of commercial technologies

from 2G to 3G, 4G and beyond .

Additionally, there were instances where

As a result of this growing trend, The Massachusetts Bay Transportation space to mount the equipment was not

Authority (MBTA), the public transportation system of Greater Boston, available and/or there was limited signal

initiated a project to provide continuous, end to end wireless coverage in the propagation. InSite had also reached a

underground stations and tunnels of its transit system. After a public bidding point where it had to work around the

process, the MBTA awarded a contract to provide and operate a neutral massive flood gates on one of the

host wireless distributed antenna system (DAS) in the subway system system’s Red Line routes. These gates are

to InSite Wireless, a company focused on the design, construction, operation, large doors that allow the tunnels to be

and maintenance of shared wireless infrastructure for complex indoor and sealed to prevent water passage during

outdoor environments. InSite specializes in neutral host DAS utilized by the construction of highway tunnels.

multiple carriers, specifically targeted at customers who seek seamless wireless

coverage in the most challenging of physical environments such as convention With all of these factors in play, antennas

centers, casinos, airports and transit systems, where either the quality of were no longer a viable option.

wireless signals is impaired by building structures or the signal capacity is

insufficient to meet uctuating occupancies.

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The Solution

InSite engineers had to design a system to To work around the ood gates, the InSite

accommodate the varied geometry of the team used existing cable sleeves (used for

tunnels and the different types of trains electricity wiring and other existing cabling)

used on each line, as well as a way to get to thread the RADIAFLEX cable through the

past the ood gates without interfering gates and into the rest of the tunnel –

with their operation. To solve problem ensuring seamless wireless service.

installation areas, the designers specified

RADIAFLEX radiating cable from RFS. Time constraints were also a key issue for®

RADIAFLEX radiating cables facilitate radio the cable installation process. Due to the

communication where the usual free space MBTA’s schedule, installers are only able to

propagation of electromagnetic waves is work when trains are not running. After

hampered, undesired or impossible - in the process of shutting down power, work

environments such as tunnels, mines, trains and other vehicles coming through,

buildings, and large complexes like the installers get an average of only 2 to

exhibition grounds or airports. 2.5 hours per night to work.

Radiating cable is similar to regular In this kind of installation process, hi-rail

antenna cable, with slots cut into the outer vehicles (trucks fitted with special train

conductor that allow the cable to work like wheels to allow them to drive on the

a sprinkler hose and “spray out” low levels tracks) are used to put hangers on the

of signal along its entire length. For wall of tunnels, which tend to be We have foundexample, a single radiating cable extending crowded, so installers have to be

RADIAFLEXto be a®1,100-1,500 feet will spread an RF signal extremely careful about where to locate

technically superior cable,out to serve a long curve. them. RFS RADIAFLEX cables include

and the quality of productnumerous features to simplify installation.

To help installers find the correct position, and ease of installation havefor example, the RADIAFLEX cable jacket

been critical factors in ouris equipped with two guides that fit

successexactly into the rear open part of RFS

standard clic clamps or in the open slots

of heavy-duty clamps. This simplification Joe MullinVice President of Engineering andcan be critical under tight time

Operations at InSite Wirelessconstraints.

Furthermore, the highest risk for

malfunction, besides cable handling, is

poor installation of connectors. RFS one-

piece connectors for radiating cable are

virtually foolproof, further simplifying the

installation process. RFS also offers a wideIn s tal le rs h ad to wor k a rou n d th e mas si ve oo d g ate s,

range of standard and special drums inwh ic h al l ow th e tu nn el s to b e sea le d to p reve nt wa terpa ss ag e du ri ng c o ns tru ct io n o f hi gh way tu n ne ls . Exi s t- order to meet specific project needs.in g c ab le s le eves w ere u sed to th rea d RA DIA FLEX c ab leth rou g h th e gat es an d i nt o th e r est o f th e t un ne l.

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TRANSPORTATION SOLUTIONS

CASE STUDY

RFS RADIAFLEXRadiating Cable Helps Provide Seamless Wireless Connectivity®

to Millions of Boston’s MBTA Subway Riders

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

There have been numerous challenges The RADIAFLEX suite of radiating cables

brought on by the rapid growth in feature RFS’ patented “higher order

wireless usage, and the resulting mode suppression technique” that

introduction of new frequency bands. allows RFS to offer cables that support

Whereas connectivity needs were once current and future in-tunnel and in-

adequately served at 800 MHz and building commercial and private radio

below, technology systems now have to services from 698 MHz to 2700 MHz for

address a wide variety of frequencies valuable cost savings. As a result of this

ranging from 700MHz up to 2700 MHz. patented higher mode suppression,

selected RADIAFLEX cables have no stop

band from 698-2700 MHz. RADIAFLEX

In designing a system cables are future-proof with respect to Th e per io d ic re pe tit io n o f t he s lo t or s lo t gr ou p c aus esres o nan c es an d h armo n ic s

such as the MBTA neutral RF spectrum re-banding / re-farming,

ensure low insertion loss and excellenthost DAS, it is critical to find

coupling performance, and featurea cable that will serve all of halogen-free, non-corrosive, low-smoke A single s lot or a gr oup

the relevant frequency of slot sand ame-retardant jacket material for

ranges efficiently. safe and reliable long-term cable Is r e pla ce d by 2 sl ot s a t

spe cific dist a nceoperation.

RADIAFLEX had the peakEa ch slot i s a gai n r e pla ce d by

performance we needed, 2 slot s at s peci fic dist a nce

while covering all of the RFS P a te nt e d highe r m ode

There are a number of supr ess ion

required frequencies.cable manufacturers; the

Th e the or y b eh in d R FS’ h ig h er ord er mo d e s u pp res si o n

challenge is finding one that tec h ni qu e

offers consistent technicalFurthermore, InSite required a radiating

performance and reliability,cable solution without stop bands to

accommodate a high-performance, while also providing anfuture-proof design for the MBTA DAS

economical solution.installation. RFS is the only company on

RFS excelled in all of thesethe market with the intellectual property

areas.and leading-edge technology to suppress

stop bands in radiating cables.

R FS pat en ted h ig h er mo de s up press io n w ith no s to p b and s

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Conclusion

To date, InSite Wireless has used close to 30,000 feet of

RADIAFLEX cable for the MBTA project, with plans to use

approximately 30,000 feet more in the project’s final phase

of completion. Upon its anticipated 2012 completion, the

MBTA installation will be the first neutral host DAS offering

end-to-end coverage throughout the entire subway —

including 35 underground stations and 19 miles of

connecting 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 EllefsonRA DI AFLEX c ab le s i nc lu de n um ero us feat ure s to s im pl if y in st all ati o n. C ab le j ac ket s are eq ui p ped Northeast Vice President ofwi th tw o gu i des th at fit e xac tl y i n to th e rear o pe n p art of R FS st and ard cl ic cl amp s, or i n th e Engineering at T-Mobileop en s l ot s of h eavy - du ty c lam ps , an d R FS o n e- pi ec e co nn ec to rs fo r rad i ati ng c ab le a re vir tu all yfo ol pr oo f.

About InSite Wireless

InSite Wireless specializes in the design, installation, operation, and maintenance of shared wireless infrastructure solutions that

enhance the quality and capacity of wireless voice and data services in public facilities and complex environments. InSite built and

launched its first DAS at the Moscone Center in San Francisco in 2001, and has developed and currently operates additional projects

in convention centers (including the Boston Convention and Exhibit Center), casinos, airports, sports stadiums, and transit systems

like 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.

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