Yohannes Bishaw presented on wireless underground sensor networks (WUSN). WUSN consist of wireless sensors buried completely underground to monitor conditions like soil information. This differs from above-ground wireless networks due to the challenging underground communication medium. WUSN offer applications in intelligent irrigation and agriculture but face design challenges including power conservation, topology planning, antenna design for underground use, and operating in harsh underground environments. The presentation covered types of wireless sensor networks, applications of WUSN, current underground sensing technology, and communication architecture considerations for WUSN.

1. State of the Art Seminar
Presentation on
IOT-WUSN(Wireless Underground Sensor networks )
Presented by Yohannes Bishaw
EmailJohn.fhy@gmail.com

2. Contents Covered
Introduction
Types of WUSN
Current technology for WUSN
WUSN design challenges
Conclusion
Application of WUSN
Communication Architecture WUSN

3. Introduction
The Internet of things (IoT) is the inter-networking of physical
devices, vehicles (also referred to as "connected devices" and "smart
devices"), buildings, and other items—embedded with electronics,
software, sensors, actuators, and network connectivity that enable
these objects to collect and exchange data.

4. Introduction…
In WUSN the node is completely underground.
 WUSN consist of wireless devices that operate below the ground
surface. These devices are buried completely under dense soil. The
main difference between WUSN and the terrestrial wireless sensor
network is the communication medium.
 Wireless Underground Sensor Networks (WUSN) have the potential to
impact a wide variety of new applications including intelligent
irrigation, soil information monitoring, etc, the internet of tings for
water-saving agriculture.

5. Types of WSN
Terrestrial WSN  Distributed in given area either in ad-hoc manner
Under Ground WSN Sensors buried underground , agriculture or
in cave or mines that monitors underground conditions.
Under Water WSN  Sensors are located under water.
Multimedia WSN  sensors are equipped with cameras and
microphones.

6. Types of WSN

7. Application of wireless underground sensor
network
Environmental monitoring of the water-saving agriculture
Safety detection of mine
Quality monitoring of underground facilities
Navigation of ground vehicle
Intelligent mines

8. Current technology for underground sensing
The current system consists of a buried sensor and a data logger on the
surface
Very useful for a variety of applications
Suffer from several shortcomings when compared to wireless
underground sensor networks
Concealment
Ease of deployment
Timeliness of data
Reliability
Coverage density

9. Concealment
In current systems the data loggers are deployed on surface
Communication is easier as no underground communication is
involved
Above ground equipment is vulnerable to agricultural and landscaping
equipment or unacceptable for aesthetic reasons
In WUSN the equipment is underground secure from any theft and
protected from damage

10. Ease of deployment
Current technology uses wired system
Tough to add new sensors or data loggers
No scalability issues with WUSN as its fully wireless
Timeliness of data
Due to wireless nature the data from sensors is forwarded in real
time to sink
In data loggers the data may be stored for later retrieval

11. Reliability
Current systems are fully dependent on data loggers
Data logger failure means whole network failure
WUSN eliminate the need of data logger
Each sensor can forward sensor readings independently
WUSN’s are self healing

12. Coverage density
Current systems require the sensor to be deployed close to the data
logger.
It results in less coverage.
WUSN eliminate the need of data logger.
Sensors can be deployed anywhere , hence increasing the coverage area.

13. WUSN design challenges
Power Conservation
Topology design
Antenna design
Environmental extremes

14. Power conservation
Underground sensor nodes require more power as attenuation is more
Difficult to recharge or replace batteries
Solar or any alternate energy form also can’t be used
Power conservation is the key
Should be implemented by using power efficient hardware and
communication protocols

15. Topology design
Considerations
Application-The density of sensor deployment is dictated by the
application. Security application require dense whereas soil monitoring
less dense deployment.
Power usage minimization-Power usage can be minimized by designing
a topology with a large number of short-distance hops rather than a
smaller number of long-distance hops.
Cost-Deeper and Denser deployments result in more costs. Establish
trade offs.

16. Underground topology
All sensor devices underground
Sink may be underground or above it
Can be single depth or multi depth
Provides maximum concealment of network
Ground air ground path can be used

17. Hybrid topology
Mixture of underground and aboveground sensor devices
Power intensive underground hops can be traded for less expensive
hops in a terrestrial network.
Terrestrial devices can be easily recharger or replaced
Network is not fully concealed

18. Antenna design
Issues to be considered
Variable requirements-Devices near the surface air interface have
different requirements from those deeper inside as they suffer from
reflection.
Size-Lower frequencies require larger antennas, this is a challenge as
sensor device size should be small.
Directionality-The antennas should be oriented for both horizontal
and vertical communication.

19. Environmental extremes
Underground environment is not ideal for electronic devices
Protection from water, animals, insects etc. is needed.
Devices should be resistant to pressure of people or objects moving
overhead

20. Communication architecture of sensor networks

21. Physical layer
Lower frequencies are ideal for WUSN
They face less attenuation but the antenna size becomes large
Lower frequencies result in lesser bandwidth
Due to this the data rate in WUSN is very less

22. Data link layer
In WUSN the focus should be on less retransmissions
Traditional link layer protocols are contention based or TDMA
based
Collision avoidance using CTS/RTS involves too much overhead
In TDMA based scheme the synchronization may be lost between
nodes

23. Network layer
Ad hoc routing protocols may be proactive, reactive or geographical
Both proactive and reactive are not applicable to WUSN due to
signaling overhead and synchronization issues
Geographical routing can be helpful for WUSN only in some cases
Routing protocols should be dynamic as link costs change due to
soil conditions, water etc.

24. Transport layer
Performs function of flow control and congestion control
Congestion control can be done by routing data to terrestrial relays
which are capable of a higher data rate
Window based mechanism for flow control may not be applicable to
WUSN as retransmissions are more
In WUSN retransmission should be less to save energy

25. Conclusion
We introduced the concept of WUSNs in which sensor devices are
deployed completely below ground. There e are existing applications of
underground sensing, such as soil monitoring for agriculture.
Sensor Networks are emerging as a great aid in improving agricultural
productivity, quality and resource optimization.
Very application dependent and close interaction between agriculture
scientist and ICT researchers will help.
Several challenges like underground wireless channel, less bandwidth,
power conservation etc.