Page 123 - From Smart Grid to Internet of Energy

Smart grid network architectures Chapter 3 107

In order to implement NANs for SG communications, network standards
such as Wi-Fi (IEEE 802.11), ZigBee Alliance (IEEE 802.15.4), WiMAX (IEEE
802.16), and WSNs may be deployed depending upon the requirement. IEEE
802.15.4g and IEEE 802.11s are two latest IEEE standards that may be used
for SG-based NANs [15]. The IEEE 802.15.4g maintains Physical Layer
(PHY) and Medium Access Control (MAC) layer architecture of SG communi-
cation networks, whereas IEEE 802.11s takes care issues related to network
operation in the SG. The low data rate wireless communication in outdoor
mediums and wireless Smart Utility Network (SUN) requirements are addressed
by the IEEE 802.15.4g. The SUN is used for the very large scattered network
having low power requirements for operation. The SUN (IEEE 802.15.4g)
consists of numerous wireless devices that are distributed over a large area
and use efficient routing algorithms for data communication [16]. Since the
SUN exploits the unlicensed frequency bands (2.4 GHz), it has to resist interfer-
ence caused by any of wireless communication system (IEEE 802.11) that is
working in the same frequency band. The IEEE 802.11s is an improved version
of IEEE 802.11, and it enhances the RF parameters at MAC layer since better
packet delivery ratio and route selection for multi-hop networks are possible in
this standard. It also provides the features of on-demand routing protocol and
tree-based proactive routing protocol. Highly secure and high-speed data trans-
mission with better routing for wireless NAN applications can be achieved
by IEEE 802.11s [17].
Topology of the network should be designed carefully so that it can support
the routing algorithms which are very efficient in nature, therefore routing pro-
tocols for SG NANs needs to be developed in a well-designed way. Obviously,
the requirements of SG communications may be addressed by well-designed
routing algorithms. Since the NANs utilize mesh topology schemes as commu-
nication network in the SG, the characteristics of these networks schemes
should also be taken into account while designing the routing algorithms. A
mesh network which is compatible with IEEE 802.15.4g is known as a Low
Power and Lossy Network (LLN) [18, 19]. Network devices work with con-
strained processing power and memory whereas low data rates are required
for operation of communication connections in LLNs. Internet Engineering
Task Force (IETF) Routing over LLNs (ROLL) working group has designed
Routing Protocol for LLNs (RPL) that can be employed as a routing protocol
in SG NANs. Nonetheless, certain revisions may be needed to address the needs
of the SG operation. Since revised version of hybrid wireless mesh protocol
(HWMP) of IEEE 802.11s provides stable, high-speed and secure data trans-
mission, many researchers have proposed to employ it as a candidate routing
algorithm for SG NANs [17].
A special type of tree-based routing protocols [18] is the RPL that uses
destination-oriented directed acyclic graphs (DAGs) as the abstractions of
one network topology, where every node is allotted with a private index