IEEE Wireless Communications - April 2017 - page 20

IEEE Wireless Communications • April 2017
18
1536-1284/17/$25.00 © 2017 IEEE
A
bstract
In this article, we consider the utilization of
TVWS by small CR network operators to support
the communication needs of various smart grid
applications. We first propose a multi-tier commu-
nication network architecture for smart metering
applications in dense urban environments. Our
measurement campaign, without any competition
from other CR operators, reveals that the com-
munication architecture can achieve more than 1
Mb/s data rates using the free unlicensed TVWS
spectrum. However, anticipating stiff competi-
tion for the unlicensed TVWS spectrum among
CR operators and to support smart grid applica-
tions with stringent QoS requirements, we further
exploit the novel idea of high priority channels
(HPCs) that a CR operator can temporarily lease
by paying a small fee. This poses several new chal-
lenges for CR operators, such as their econom-
ic viability while providing QoS guarantees. We
develop a real-time decision support framework
with several adjustable parameters for CR oper-
ators that enables them to trade off HPC leasing
cost and QoS. The developed algorithms are
simple rules that provide significant opportunities
to CR operators to maintain a balance between
spectrum cost and QoS depending on dynamic
spectrum availability and smart grid application
requirements.
I
ntroduction
Smart grid is a green technology that allows the
integration of renewable energy sources and
demand response management. The Internet
of Things (IoT) and machine-to-machine (M2M)
communications are the major drivers of smart
grid deployment and applications, particularly
in residential and commercial buildings. IoT is a
broad futuristic vision where a network of “things”
such as sensors, objects, and nodes is formed to
connect and unite the physical and digital worlds
[1, 2]. The “things” are often called “machines”
when they sense, collect, and communicate use-
ful data with minimal human intervention. M2M
communication is used for automated data trans-
mission between various machines. Currently,
M2M connections account for 2.8 percent of the
total worldwide mobile connections, and nearly
428 mobile operators offer M2M services across
187 countries [3]. It is expected that by 2022,
there will be around 18 billion M2M connections.
Addressing the ever increasing data rate demands
of dense M2M networks in smart grids requires
novel network architectures and efficient utiliza-
tion of communication resources [4].
It is needless to point out the scarcity of wire-
less spectrum and the usefulness of cognitive
radio (CR) technology, which allows opportunis-
tic reuse of wireless spectrum. In recent years,
due to the transition from analog to digital TV
broadcasts, some spectrum in the very high fre-
quency (VHF) and ultra high frequency (UHF)
bands are also becoming available. This spectrum
is commonly known as TV white spaces (TVWS)
[5]. Several countries have already laid out regu-
latory frameworks for TVWS utilization, for exam-
ple, the Federal Communications Commission
(FCC) in the United States [6], the Office of Com-
munications (OFCOM) in the United Kingdom
[7], and the Info-Communications Development
Authority (IDA) in Singapore [8]. There is a gen-
eral consensus among the spectrum regulators
to provide unlicensed access to TVWS. Given the
attractive propagation characteristics in the VHF
and UHF bands and relatively larger frequency
blocks, there are also some efforts to standard-
ize the use of TVWS spectrum. For example, IEEE
802.11af, also sometimes referred to as “White-
Fi” or “Super WiFi,” adds the TVWS bands to the
IEEE 802.11 family of specifications. TVWS has
been touted as an untapped resource that has
the potential to unleash a myriad of new M2M
applications and services. Moreover, unlike tradi-
tional licensed wireless operators, free availability
of TVWS spectrum provides a great opportunity
for many new small and virtual CR operators to
set up their networks for smart grid applications
at very low cost. In this article, any operator using
free unlicensed spectrum bands without owning
any other wireless spectrum bands is considered
to be a small and virtual CR operator.
To ensure non-interfering spectrum access,
a CR operator can acquire spectrum availabili-
ty information either through spectrum sensing
or by contacting a geo-location database [9]. In
spectrum sensing, a CR operator is responsible for
spectrum sensing and managing its transmissions
to avoid unnecessary interference. In the geo-lo-
cation database method, a CR operator obtains
spectrum information from a service provider
that maintains a complete database of spectrum
availability at different locations by employing
sophisticated spectrum sensing techniques. The
geo-location database method has some addition-
al signaling overhead for CR operators. However,
N
aveed
U
l
H
assan
, W
ayes
T
ushar
, C
hau
Y
uen
, S
ee
G
im
K
erk
,
and
S
er
W
ah
O
h
G
uaranteeing
Q
o
S U
sing
U
nlicensed
TV
W
hite
S
paces
for
S
mart
G
rid
A
pplications
S
mart
G
rids
Naveed Ul Hassan is with
Lahore University of Manage-
ment Sciences (LUMS).
Wayes Tushar and Chau Yuen
are with Singapore University
of Technology and Design.
See Gim Kerk is with Power
Automation.
Ser Wah Oh is with Whizpace
Pte Ltd.
Digital Object Identifier:
10.1109/MWC.2017.1600267WC
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