Page 238 - From Smart Grid to Internet of Energy

Cognitive radio based smart grid communications Chapter 6 211

system parameters to exploit best available wireless channels around it [12].
This approach was first introduced by Joseph Mitola III in 1998 and was
reported in 1999 [13]. According to this approach, the CR was described as
a smart wireless communication system that is able to perceive radio medium
and employ artificial intelligence techniques to figure out detection results.
Later, CR system can dynamically arrange its configuration parameters (i.e.,
waveform, operating frequency, protocol and networking) to enable communi-
cation over different frequencies at different times. Spectrum holes are oppor-
tunistically exploited by this technology for data transmission. The concept and
practice background of this technology have evolved over the past few years. In
2003, the FCC has formally declared the definition of this technology as follows
[14]:

A radio or system that senses its operational electromagnetic environment and can
dynamically and autonomously adjust its radio operating parameters to modify
system operation, such as maximize throughput, mitigate interference, facilitate
interoperability, access secondary markets.
While licensed spectrum access priority is always assigned to Primary Users
(PUs), Secondary Users (SUs) that are authorized by the CR can also employ
the licensed spectrum for data transmission, and no interference to PUs should
be guaranteed by the SUs. Thus, effective usage of spectrum bands can be
ensured by the CR technology [15, 16]. Up until now, numerous advances in
CR technology have been attained thanks to the performed researches and pro-
motion of regulators. In addition, various standards have been suggested to
advance design and applications of CR technology. In 2004, the Institute of
Electrical and Electronics Engineers (IEEE) has created a working group enti-
tled IEEE 802.22 to improve international standards for this technology, and the
working group developed IEEE 802.22 standard that focuses on wireless
regional area network (WRAN) by considering white spaces in the television
(TV) frequency spectrum. The main goals of this standard is to provide efficient
usage of unused spectrum that are assigned to TV broadcast services, and the
standard was published in 2011. The following sections will present technical
features of the CR and CR network (CRN) applications in smart grids in a detail.

6.2 Cognitive radio technology

The CR technology has appeared as an emerging technology aiming efficient
utilization of restricted spectrum in addition to supporting more wireless appli-
cations and services [17]. Therefore, this technology is generally considered as
a crucial enabling technology for modern communication and network systems.
In this technology, the use of spectrum can be also advanced through an oppor-
tunistic spectrum access method that exploits unoccupied part of spectrum allo-
cated to the PUs for tentative usage of SUs [18, 19]. A CR transceiver can
dynamically configure its system parameters to utilize unemployed parts of