Page 94 - From Smart Grid to Internet of Energy

Smart metering and smart monitoring systems Chapter 2 79

2.3.2.3 Wide area network
WAN operates as a backbone between DA and power network operators by
supporting two-way communication. The bulk generation, transmission and
distribution systems including power plants, substations and distribution trans-
formers communicate with utility grid over WAN architecture. The communi-
cation technologies of WAN network can be more than one of wireline and
wireless technologies including IEEE 802.16 WiMAX, GPRS, UMTS, LTE,
ADSL, LoWPAN, fiber optics and routing over low power and lossy networks
(RPL). GPRS provides data transmission bandwidth up to 172 kbps while the
latest cellular technology, LTE, increase this rate up to 300 Mbps in coverage
area and 75 Mbps for mobile users. The WiMAX, which is an execution of
IEEE 802.16 standard for metropolitan area networks (MANs) is one of the fun-
damental technology providing connection between data management point
(DMP) and smart meters in WAN architectures.
WiMAX is based on orthogonal frequency division multiple access
(OFDMA) that is the multi-user adaptation of regular OFDM digital modu-
lation scheme. The multi-user structure is obtained in OFDMA by arranging
the subsets of several subcarriers to unique consumers that allow simulta-
neous data transmission from a huge group of consumers in low data rates.
The recent internet protocol (IP) that is called IPv6 brings a huge addressing
space facilitating integration of millions of devices to WAN infrastructure.
The 6LoWPAN denotes IPv6 enabled LoWPAN and operates between IPv6
and MAC layer of IEEE 802.15.4 to provide IPv6 support in data manage-
ment. The constrained application protocol (CoAP) is a downscaled version
of Hyper-Text Transfer Protocol (HTTP) on the User Datagram Protocol
(UDP) for constrained resource applications to tackle challenges met in
IPv6 transmission over LoWPAN. On the other hand, one of the fundamental
contribution of CoAP is its support for machine-to-machine (M2M) commu-
nication and mutual HTTP conversion due to constrained internet
protocol [2, 13].

2.3.3 Remote control features

Smart meters are not only used to transmit measured consumption data but
also for special control requirements of smart appliances due to two-way
communication capability. The smart meter enables users or service opera-
tors to turn on or turn off any specific residential device through communi-
cation link. Besides, smart appliances can be associated with HEMS and
consumers can manage residential environment in terms of security, comfort
or control by controlling surveillance cameras, heating, ventilating and air
conditioning (HVAC) systems, washing machines or other devices on
demand. The control operations are performed by wireless or internet-based
user interfaces that also provides instant and previous consumption data of
residential grid [10].