Mass Transit - 34

WIRELESS NETWORKS
tion. Automation of transit lines
is one of the most cost-effective
ways to increase capacity, which
is achieved through shorter
headways. However, automated
subways and light rail place additional large burdens on communications. Additional CCTV
cameras for obstacle detection
must be installed and managed
onboard, with imagery constantly
sent to the control center. Numerous additional CCTV cameras are
needed inside the train for passenger security. Supporting the
enormous amount of data generated by these cameras requires an
ultra-broadband, ground-to-train
radio network.
Most Wi-Fi networks in place
on metros are incapable of carrying both safety-critical and
non-safety-critical traffic, due
to limitations such as a lack of
sophisticated quality of service
(QoS) support and shortcomings
with mobility. Wi-Fi also uses unlicensed spectrum, meaning both
interference from other users and
the risk that a hostile party could
seek to jam or invade the network,
undermine safety. Additionally,
standard Wi-Fi does not monitor
the quality of the air interface in
real time, which is essential for
any mission-critical service.
Fortunately, there is an answer on the way. It begins with
the introduction of new wireless
spectrum in North America called
Citizens Broadband Radio Service
or CBRS. The U.S. government
has released this spectrum in the
3.5GHz band, which was previously reserved for military applications. It is specifically designated
for private wireless networks using
the 4G/LTE mobile protocol. These
private LTE networks can be deployed not only as a replacement
for WiMAX and Wi-Fi, but potentially all other legacy communications systems - greatly reducing
complexity, operating costs and
improving safety and reliability.
LTE is normally used by mobile telecom companies to pro-

34 |

vide broadband cellular wireless
services. It is a much more robust
and secure system than Wi-Fi, for
instance. It is deployed worldwide
and it has a well-developed ecosystem of end devices and suppliers.
It also overcomes all of the issues
associated with Wi-Fi. It is a highly
secure, mobility-oriented standard
that accommodates high bandwidth, IP-based applications with
full control over QoS for real-time,
full duplex voice and video applications. It has very low latencies
(down to 10ms) as well, so that it
can support GoA level 3 driverless
train operation (DTO) and level 4
unattended train operation (UTO).
The LTE standard includes
multiple encryption and authentication features, rendering it
secure by default. Additionally,
when properly designed, an LTE
network has several mechanisms
for auto-reconfiguration in case
of network failure - vital for an
always-on railway communication network. These attributes
make LTE superior for building
a radio network able to support
passenger connectivity needs,
along with mission-critical operational applications such as
train signaling, CCTV on-board
and emergency communications.
If installing mobile cellular
technology in a transit network
sounds daunting and expensive,
the good news is that it is now
almost as easy to install a private 4G/LTE network as a Wi-Fi
mesh network. In fact, a 4G/LTE
network requires less installation
infrastructure than a Wi-Fi network, since it needs less trackside
radios to achieve a similar coverage. And, yet, it is far more robust,
secure and capable of supporting
far greater numbers of connections per access point. In terms
of size and installation, there are
now small cell 4G/LTE access
points that are no larger or more
complicated than a Wi-Fi access
point and also feature plug-andplay installation. Multi-racks of
servers for the mobile packet core

Mass Transit | MassTransitmag.com | JUNE 2019

have now been reduced to the size
of a mini desktop PC.
For those worried that LTE will
soon be supplanted by 5G, don't
be. Although the first 5G networks
are being rolled out in 2019-2020,
the ecosystem of devices and interfaces is far from mature. And,
most of the features that 5G brings
that are advantageous to the transit industry have already been incorporated into the later releases of
4G/LTE, including solutions that
meet 5G performance levels such
as jitter and delay.
Until recently, 4G/LTE has not
been much discussed in the trans-

Nokia Networks

portation space because the radio
spectrum licenses have all been
allocated to mobile operators.
With CBRS, 4G/LTE is becoming available; capable of meeting
the needs for a single converged
communications system that
not only supports automation
and data in general, but all of the
legacy communications systems
as well. There are already various
private LTE trials underway in the
transportation space.
With private LTE, transit operators can safely and securely
implement driverless technology,
implement IoT, CCTV, telephony networks and provide mobile
broadband on-board services for
their customers. The release of
the CBRS spectrum for private
LTE networks is, thus, a game
changer for the North American
transit industry.

IMPROVED
COMMUNICATIONS
networks holds
the promise
of shorter
headways using
automated trains
for improved
capacity.

Pedro Bontempo
Elmadjian is
customer solution
manager, Enterprise
at Nokia Networks.


http://www.MassTransitmag.com

Mass Transit

Table of Contents for the Digital Edition of Mass Transit

Ad Index
Editor's Notebook
People & Places
TTC faces a forced reset
Special Report: The state of passenger rail
Making a safe and comfortable stop
Not all wireless is created equal
Video aids agency monitoring efforts
Best Practices
Products
Classifieds
Social Hubs
Rail Product Guide
Mass Transit - 1
Mass Transit - 2
Mass Transit - 3
Mass Transit - 4
Mass Transit - 5
Mass Transit - Ad Index
Mass Transit - 7
Mass Transit - Editor's Notebook
Mass Transit - 9
Mass Transit - People & Places
Mass Transit - 11
Mass Transit - TTC faces a forced reset
Mass Transit - 13
Mass Transit - 14
Mass Transit - 15
Mass Transit - 16
Mass Transit - 17
Mass Transit - 18
Mass Transit - 19
Mass Transit - Special Report: The state of passenger rail
Mass Transit - 21
Mass Transit - 22
Mass Transit - 23
Mass Transit - 24
Mass Transit - 25
Mass Transit - 26
Mass Transit - 27
Mass Transit - 28
Mass Transit - 29
Mass Transit - Making a safe and comfortable stop
Mass Transit - 31
Mass Transit - Not all wireless is created equal
Mass Transit - 33
Mass Transit - 34
Mass Transit - 35
Mass Transit - Video aids agency monitoring efforts
Mass Transit - 37
Mass Transit - Best Practices
Mass Transit - 39
Mass Transit - 40
Mass Transit - 41
Mass Transit - Products
Mass Transit - 43
Mass Transit - 44
Mass Transit - Classifieds
Mass Transit - Social Hubs
Mass Transit - 47
Mass Transit - 48
Mass Transit - Rail Product Guide
Mass Transit - R2
Mass Transit - R3
Mass Transit - R4
Mass Transit - R5
Mass Transit - R6
Mass Transit - R7
Mass Transit - R8
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