Energy Harvesting for Wireless Sensor Networks

This assignment explores the concept of energy harvesting for powering wireless sensor networks. It discusses different mechanical-to-electrical conversion methods like electromagnetic induction and kinetic energy conversion. The text also highlights the use of energy harvesting in wireless communication technologies such as WiMAX, Bluetooth Low Energy, and ZigBee. Challenges associated with energy harvesting are addressed, along with future trends and advancements in this field.

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Wireless Communication Assessment

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Table of Contents
Task 1..........................................................................................................................................................3
Comparison of data encryption standards for WiMAX Networks............................................................3
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP):.............3
Triple Data Encryption Standard(3DES):..............................................................................................3
Advanced Encryption Standard (AES):.................................................................................................3
Task 2:.........................................................................................................................................................4
Security challenges for WPAN technologies............................................................................................4
Bluetooth:............................................................................................................................................4
ZigBee:.................................................................................................................................................4
Task 3:.........................................................................................................................................................5
Reflection on the topic of Energy Harvest...............................................................................................5
Introduction.........................................................................................................................................5
Discussion............................................................................................................................................5
Analysis................................................................................................................................................6
Explanation..........................................................................................................................................7

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Task 1
Comparison of data encryption standards for WiMAX Networks
Counter Mode with Cipher Block Chaining Message Authentication Code Protocol (CCMP):
It employs 128-bit keys and a 48-bit initialization vector which minimizes replay attacks
vulnerability (Syed A. Ahson, Ocober 2012). Counter Mode with Cipher Block Chaining
Message Authentication Code Protocol provides data privacy, authentication, and integrity.
CCMP encryption standard may need more advanced hardware since it requires extra processing
power.
Triple Data Encryption Standard(3DES):
Triple data encryption standard uses three keys that are different each with a length of 56-bit.
The three keys often cause the performance to be slow in most software, and therefore the Triple
Data Encryption Standard is getting obsolete with time.
Advanced Encryption Standard (AES):
Advanced Encryption Standard supports 128-bit, 192-bit and 256-bit encryption keys (Jeffrey G.
Andrews A. G., 2011). It is, therefore, faster than Triple Data Encryption Standard which uses
56-bit encryption keys. Advanced Encryption Standard uses less memory and is easily
implemented. However, Advanced Encryption Standard is not used by all end-user terminal
keeping Triple Data Encryption Standard still in use (Alejandro Aragn, September 5, 2017).

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Task 2:
Security challenges for WPAN technologies.
Bluetooth:
Bluetooth Wireless, Personal Area Networks, are vulnerable to eavesdropping (Kevin Townsend,
May 22, 2014). An attacker may make an independent connection with the involved victims and
send messages between the two in a way that makes them think they are only communicating
with each other on the private connection (Heydon, November 7, 2012).
ZigBee:
ZigBee’s security layer is built on the Residential mode security mode which uses a single key
for all the personal Area Network in all the connected applications (Faludi, January 3, 2011). The
main security vulnerability in this mode is the lack of a security protection of packets from a
suspected malicious node within the network.

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Task 3:
Reflection on the topic of Energy Harvest
Introduction
Wireless communication industry has massively continued to grow as more embrace the
technology and its elegance. However, the full functionality of wireless networks used to relay
the communicated information is primarily dependent on energy. It has been a challenge
providing energy to all the devices used to set up a working wireless communication system due
to the impossibilities of replacing batteries in some of the devices used and the cost of the
replacements when possible (Sheikh, 2017). Some devices may be placed in locations that
cannot be easily accessed when there is need to replace the battery while some locations may not
have electricity at all.
Discussion
Energy harvest is an excellent solution to the challenges stated above. Using energy from
the surrounding environments such as the wind and solar energy may solve all the energy
problems. Most devices will be placed in places where there is at least one environmental source
of energy that can be used and cater for all the energy-related problems that the device would
have heard (Ulukus, et al., 2015).
Even though there are some challenges that still need to be addressed to be able to
develop energy harvesting systems that are efficient, cost-effective, and reliable for the wireless
sensor network environment, the energy harvesting technique remains a great invention that
needs to be more researched and implemented.

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Analysis
Wireless sensor network devices that operate in the atmosphere will have a great benefit
not need electricity. It is naturally hard to get to the devices that have been set to operate from
the atmosphere. If energy harvesting is done, the device will minimize downtimes by having
enough power all the time without the need for anybody going there. Some of these networking
devices are managed remotely. For the devices managed remotely, there will be no need for
visiting the precise location of the device since the power may be sufficient for a long period.
Other wireless sensor network devices use electricity and will also benefit from the
energy harvesting. Devices that do not use batteries need electricity that flows without
disruptions. Most companies offering electricity to companies and organizations with these
devices do not guarantee electricity flow all the time of day all days (Alireza Khaligh, December
2010). At times, it happens that there are blackouts that will affect the working of the devices
and tamper with the communication services. The Energy from the harvest sources would not
guarantee full-time energy, but at least there would be no disconnection time when the source of
power is more than one. After advancements, the power would possibly be enough, and the
devices would only rely on the harvested energy.
Wireless networks have recently been the adopted by most systems that use networks to
communicate. The operation of the wireless network provides for efficient systems that are
independent of location barriers and structure of the buildings in the company. Recent
applications of the wireless network include networks used for environmental monitoring,
networks used for controlling and tracking animals and those used for Safety, security, and
military applications. Others are used to manage health applications and built environments.

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All the wireless sensor networks have nodes with a structure that has a memory module,
communication module and the processor. Each module requires power to work. It will be easy
to work with the system when the power comes from a system within the wireless sensor
network device. The implementation of the energy harvester involves adding a module that
harvests the ambient energy and another one that manages the generated energy. Some energy is
kept in the store while some are directly used.
When the energy source is not available, for instance, the wind is not flowing, and the
energy harvester was using the wind, the system will use the stored power. The power works
sufficiently since no power is consumed from the store when the harvester can harvest. This
makes the system work at all time provided the environmental factor used to generate the energy
will be available at some time before the energy in the store is exhausted.
It is easy to manage the energy harvested since it is possible to improve the amount
harvested by a given harvester and store the energy in bigger stores that will carry enough power
to use for all the period the environmental resource being used to generate the energy may be
unavailable. This will help increase the efficiency and availability of the system.
Explanation
Most of the WSN devices that support energy harvesting work based on the piezoelectric,
electrostatic effects and electromagnetic effects. The systems basically try to convert vibrations
into electric energy. One system uses a mass-spring while the other is mechanical to electrical
converter. The mass-spring system is responsible for transforming vibration received from the
environmental resource in use to generate motion between two elements that are connected to a
single axis. On the other hand, the mechanical to electrical converter takes in the relative motion

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generated and transforms it into electrical energy. The system does this by exploiting one of the
three effects stated above.
The mechanical to electrical converter working by exploitation of the Piezoelectric effect
generate electric potential after twisting, compressing or distorting some piezoelectric crystals.
The piezoelectric material causes deforms the internal structure of the molecules shifting charge
centers from positive to negative and vice versa when put under external forces such as
compression or twisting (Lu, 2015). The shift produces some microscopic polarization to the
material. The polarization produced is normally directly proportional to the applied force.
The polarization results into a potential difference across the material that generates an
Alternating Current. The Alternating current generated is converted to the required Direct
Current through the use of a diode rectifier.
The mechanical to electrical converter working by electromagnetic effect is ruled by
Lenz’s law such that any change in the magnetic condition of the involved coils outputs an
electromotive force. The electromotive force generated induces some voltage to the coil in use.
Relating to the system above, the magnet acts as the mass in the spring system producing some
parallel movement to the coil axis (Mathna, 2012). The parallel movement induces an
Alternating Current in the secondary coil which produces the required energy for powering our
device.
The mechanical to electrical converter working by kinetic energy also operates just like
the previous systems working by vibrations. The turbine in use normally converts the flow of the
wind or the water being used for rotational movements working on the windmill or turbine in use

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(Chetwynd, 2010). The movement of the turbine or the windmill is used to drive an
electromagnetic generator that generates the energy required as explained in the systems above.

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References
Alejandro Aragn, A. Z. (September 5, 2017). Indoor Wireless Communications: From Theory to
Implementation 1st Edition. Wiley;.
Alireza Khaligh, O. C. (December 2010). Energy Harvesting: Solar, Wind, and Ocean Energy
Conversion Systems (Energy, Power Electronics, and Machines) 1st Edition. CRC Press.
Chetwynd, M. M. (2010). Investigation of a resonance microgenerator. Journal of
Micromechanics and Microengineering, 12-17.
Faludi, R. (January 3, 2011). Building Wireless Sensor Networks: with ZigBee, XBee, Arduino,
and Processing 1st Edition. O'Reilly Media.
Heydon, R. (November 7, 2012). Bluetooth Low Energy: The Developer's Handbook 1st Edition.
Prentice Hall; 1 edition .
Jeffrey G. Andrews, A. G. (2011). Fundamentals of WiMAX: Understanding Broadband
Wireless Networking 3rd Edition. Prentice Hall.
Kevin Townsend, C. C. (May 22, 2014). Getting Started with Bluetooth Low Energy: Tools and
Techniques for Low-Power Networking 1st Edition. O'Reilly Media.
Lu, X. (2015). Wireless Networks With RF Energy Harvesting: A Contemporary Survey.
Communications Surveys Tutorials, 33-37.
Mathna, C. (2012). Energy scavenging for long-term deployable wireless sensor networks.
Talanta .
Sheikh, F. K. (2017, 02 25). Econpapers. Retrieved from Energy harvesting in wireless sensor
networks: A comprehensive review:
http://econpapers.repec.org/article/eeerensus/v_3a55_3ay_3a2016_3ai_3ac_3ap_3a1041-
1054.htm
Syed A. Ahson, M. I. (Ocober 2012). WiMAX: Technologies, Performance Analysis, and QoS
(WiMAX Handbook) 2nd Edition. CRC Press;.

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Ulukus, S., Yener, A., Erkip, E., Simeone, O., Zorzi, M., Grover, P., & Huang, K. (2015, January
15). Energy Harvesting Wireless Communications: A Review of Recent Advances.
Retrieved from IEEE Xplore Digital library:
http://ieeexplore.ieee.org/document/7010878/