Cyber-Physical Systems

Cyber Physical Systems (CPS) can include smart grids, autonomous car systems, process control systems, robotics automatic avionics and more [1]. Cyber Physical Systems (CPS) can include smart grids, autonomous car systems, process control systems, robotics automatic avionics and more [1]. Wireless communication technologies can be compared using several factors including the following: Communication spectrum All wireless technologies used varied communication spectrums.

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Introduction
The design of cyber-physical systems is more and more dependent on wireless networks, sensors and
actuators that are connected together by IoT technology. Cyber Physical Systems (CPS) can include
smart grids, autonomous car systems, process control systems, robotics automatic avionics and more
[1]. Cyber Physical Systems (CPS) commonly contains both physical and a cyber-systems. The physical
system is controlled by a system of networks comprising of some device sensors with wireless,
computing and communicating abilities called a cyber-system. CPS focuses on physical systems, and
triggering actions to improve the behaviour of a physical environment so that it can work much more
correctly and better [2]. The success of CPS system largely depends on efficient latency, throughput,
range and low energy consumption of the connected devices. Wireless networking technologies are
used with CPS to provide the design and platform for CPS. Understanding wireless networks principles
and standards is thus important for effective CPS. This report compares several wireless communication
standards applied in the design of CPS in relation to specific measures. It also seeks to evaluate
examples of wireless communication standards for CPS and IoT. Additionally, it evaluates wireless
network performances and suggests the best wireless standard to implement CPS.
1. Comparison of wireless communication technologies
Wireless communication technologies can be compared using several factors including the following:
a) Communication spectrum
All wireless technologies used varied communication spectrums. They are widely implemented for the
infrared range (IR), radio frequencies (RF) and as transmission media. They operate in different wave
bands and hence have frequencies that cannot interfere with each other. Many wireless technologies
use radio spectrums of between 30MHz and 30 GHz because they are not affected by the curvature of
the earth and only require moderately sized antennas [3] . Communications spectrums for wireless
systems are assigned in licensed frequency bands and differ according to country and region.
b) Modulation techniques
Modulation refers to the process of converting data into transmission signals. Wireless signals originally
only had a single carrier frequency called Amplitude Modulation (AM), used for AM radio. They were
followed by Frequency Modulation (FM) and Digital Modulation for mobile systems. Other modulation
techniques for wireless include Multiple Input Multiple Output (MIMO). The type of modulation affect

the communication spectrum. Multicarrier modulation is currently being used by many wireless
standards. It divides transmitted bits into very many streams and send them over multiple sub channels
[3].
c) Medium access control mechanism
For medium access control, wireless standards use Time Divisions Multiple Access (TDMA) which assigns
time allocations to frequency between sender and receiver channels, Code Division Multiple Access
(CDMA) which sends wireless signals over a wide band, and Frequency Division Multiple Access (FDMA)
which allocates a frequency to a sender and receiver transmission channels.
d) Network topologies
A network topology refers to the physical arrangement of devices in a network. Different wireless
standards implement different topologies. Both ZigBee and Z-Wave implement Mesh network device
arrangement. Others including Bluetooth and Bluetooth low energy adopt a scattered device
arrangement. The arrangement is based on whether a network has a hub or is working in a peer to peer
fashion.
2. Cyber- physical systems and Internet of Things wireless communication standards
a) UHF RFID and NFC
Ultra High Frequency (UHF) Radio Frequency Identification (RFID) is a wireless communication protocol
which uses electromagnetic signals to pinpoint and track object tags that containing electronic
information [4]. This technology therefore allows items to be uniquely identified using radio waves. On
the other hand, Near Field Communication (NFC) is a technology that facilitates communication
between two electronic devices when they are close to each other. NFC is a specialized subcategory of
the RFID technology that operates at 13.56 MHz frequency. Both RFID can be used in cyber physical
systems with NFC designed enable a secure form of exchange of data [5]. Active RFID systems have
demonstrated great potential for connecting and building highly interrelated physical information
systems [6]. NFC technology is also used to facilitating peer-to-peer communication among devices in
cyber physical systems.

RFID NFC
Operating Distance Can transmit beyond several meters Limited 10cm(4 inches)
Frequency 13.5 MHz 13.5MHz
Use Wide range of use Needed when security is required
b) ZigBee and Z-Wave
Both ZigBee and Z-Wave are popular wireless technologies for smart devices home automation. Today,
ZigBee technology is used to serve as a sensing and control wireless standard for cyber physical systems
in residential, commercial, and industrial areas. ZigBee connects network devices in a mesh
arrangement so that information can be transmitted from one device to the other until it reaches the
network hub without the need for high-power transmitters. ZigBee requires very little power and
devices can last for a long time with one set of batteries or use no batteries at all.
Like ZigBee, Z-Wave is a wireless standard for home automation that is implemented for automated
heating, lighting, security, appliances, and smart devices. Its original use was to help users remotely
control and monitor their home smart devices. A Z-Wave network hub serves as the network home
controller and allows wireless communication between more 230 devices.
Both use mesh topologies to connect sensor devices that can communicate signal across each other and
back to the hub. Additionally, they use AES 128 encryption for security. However, ZigBee can handle
high data rates since it operates in 2.4 GHz range whereas Z-Wave uses 908 MHz’s ZigBee can only
transmit 35 feet compared to Z-wave 100 feet [7]. Below is the summary of the comparison between
ZigBee and Z-Wave.
ZigBee Z-Wave
Operating Distance 35 feet 100 feet
Hub Requires hub Requires Hub
Topology Mesh Mesh
Data Rate 40- 250 kbps 9.6 – 100 kbps
Max Network Devices 65,000 232
Frequency 915MHz/ 2.4 908/ 916 MHz
Security AES-128 symmetric encryption AES-128 symmetric encryption

c) Bluetooth and Bluetooth Low Energy (BLE)
Both classic Bluetooth and Bluetooth Low Energy (BLE) are wireless networking protocols designed to
transmit data among devices that are near each other through radio transmissions with frequencies of
2. 4 – 2. 48 GHz but use separate channels [8]. The technologies are used in stationary and mobile
devices for connecting devices high security. Bluetooth Low Energy is an improved version of Bluetooth
and has very low energy consumption, low cost and enhanced range [9]. BLE can be very effective for
cyber physical systems since applications can run on battery for close to 5 years and is always inactive
until a connection is initiated. Both are good for sensors that require to exchange small amounts of data
frequently. Below are summarized features for Bluetooth and BLE.
Bluetooth Bluetooth Low Energy (BLE)
Frequency 2400–2480 MHz 2400 MHz
Frequency Channel 79 1-MHz 40 2-MHz
Energy Consumption High energy consumption
(1 Watt)
Low energy consumption (0.01–
0.50 Watt)
Security 56 to 128 bit security layer 128 bit Advanced Encryption
Standard
Operation distance 100m 100m
Topology Scatternet Scatternet
d) Cellular Systems
Cellular systems represent a wireless communication technology where strategically located cells with
low-power radio antennas exchange data over a wide area. Cells are interconnected through a central
exchange and their identity, location and frequency is managed by several cells without interrupting

transmission. Cellular systems are becoming an integral part for cyber physical systems [10]. They
provide network coverage for devices and sensors on the move, support more connections, and reduce
power consumption. They can be used for personal, public, industrial, and home automation including
smart metering, lighting, livestock breeding, waste management, environment monitoring, irrigation
and more.
e) IEEE 802.11P
IEEE 802.11p is a wireless communication technology and a modified version of IEEE 802.11. It is used to
provide wireless access for vehicular communication systems [11]. The standard included 802.11
enhancements that are needed to sustain Transportation Systems and applications. It facilitates data
transmission amongst vehicles and roadside infrastructures and uses a frequency band of 5.9 GHz.
f) Low-Power Wide Area Networks
LP-WANs are low-cost networks designed for applications that require limited data exchange. They
implement long-lasting battery-powered sensors. Unlike the wireless standards discussed above which
are costly to design and maintain, LP-WANs include low cost hardware and installation, long-lifetime
battery life, provide secure communications, and offer interoperability, and easy deployment [12].
3. Wireless Network Performance
In my opinion, Low Powered Area Network wireless standard will be a major standard for cyber physical
systems across the globe. They provide low cost hardware and network installation. LPWA consume the
lowest energy compared to other standards. Other wireless technologies are therefore limited in terms
of energy consumption. Additionally, cyber physical systems will be required to serve a diverse range of
industries from health, manufacturing to automotive, and increasingly cover a wide range of
applications and deployment scenarios. Short range wireless technologies including Bluetooth, ZigBee,
BLE, Z-Wave and the rest cannot work effectively and hence cannot ensure good connectivity.
Benefits of LPWANs over other wireless standards
 Low energy consumption with devices lasting over 10 years after system charge
 Sends small amounts of optimized data

 Low device costs
 Requires only a few stations/bases to operate
 Easy to install
 Covers both long and short distances
 Provides authentic networks
 Sufficient network coverage and penetration
Conclusion
Technology is growing tremendously. There’s increased growth of Cyber Physical systems and
technologies such as IoT are progressively growing. More and more devices need to be connected to
others for easy and fast data migration. As a result, it is important to seek and understand available
wireless connecting options necessary for such systems for successful designs, operations, maintenance
and sustainability. From the report, it is clear that there are many wireless communication standards
that can be used to accommodate growing technology innovations including computer networks.
Wireless technologies is one of the fastest growing sectors of the communication industry. Cellular
systems have expanded significantly in the last decade with cellular devices becoming an integral tool
for both personal and business related operations. Additionally, wireless local area networks have
replaced cabled networks at home and for businesses. Many new applications such as Low Powered
Wide Area Networks (LPWA) have developed in order to enable low cost network installation and low
cost power consumption. Many innovations including wireless sensor networks, automated factories,
smart devices, smart home, smart farming, and telemedicine all require wireless communication for
growth and sustainability. Internet of Things and cyber Physical Systems will continue to require stable
and low power consumption wireless technologies as wireless communications will increasingly be
required to support information exchange between devices and people in the coming decades. Since
there are many wireless standards, and each has varying frequency bands, communication spectrum,
modulation frequency and each may support a different topology, it is important to first understand the
cyber system and physical system architecture in order to design, install and implement a suitable
wireless technology to achieve maximum network performance optimality.

References
[1] S. K. Gehrig and F. J. Stein, "IEEE/RSJ International Conference on Intelligent Robots and Systems.,"
in Dead reckoning and cartography using stereo vision for an autonomous car, Kyongju, 1999, pp.
1507 -1512.
[2] Y. Y. X. K. C. Eric Ke Wang, "2010 IEEE/ACM International Conference on Green Computing and
Communications & 2010 IEEE/ACM International Conference," Security Issues and Challenges for
Cyber Physical System, vol. 1, no. 1, p. 733, 2010.
[3] G. Andrea, "Spectrum Allocations for Existing Systems," in Wireless Communications, 2005, pp. 24-
25.
[4] A. Butters, Radio Frequency Identification: An Introduction for Library Professionals, Australasian