This paper won the III Prize in an IEEE conference (Uudaan \'07), organised by SRM University, Chennai.

1. By
Sharad Saurabh
3rd year, Dept. of Instrumentation & Control
SRM University
&
Sayan Chakrabarty
3rd year, Dept. of Instrumentation & Control
SRM University
1

2.  Ad-hoc literally means Something ‘created or done for a
specific purpose only’.
 Ad-hoc network is a dynamic network which can be
created anywhere with just two basic nodes and does
not require any centralized infrastructure.
 Each node has a certain range of communication in
which it can transmit or receive data.
 If it needs to communicate to a node which is outside
its range, it may do so by sending the data to a node
which is within its range. That node will transmit to
the next and so on till it reaches its designated
destination.
 Data is transmitted in the form of small packets.
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3. Devices such as laptops, PDAs, mobile phones, MP3 players etc,
can be made to interact using Ad-hoc networking
In fact this is being used in technologies such as Bluetooth and Wi-Fi
to connect various devices. Now-a-days, most of the above
mentioned devices come with in built facilities to support ad hoc
networking.
3

4. Contemporary communication means in aircrafts include :
 Radio Communication from ground (TIS-B)
 RADAR (Radio Detection and Ranging):
Air Traffic Control (ATC) Radars
Secondary Surveillance Radar (SSR) (Airport Surveillance Radar)
Ground Control Approach (GCA) Radars
PAR Systems
Distance Measuring Equipment (DME)
Radio Beacons
Identification Friend or Foe (IFF) Systems
IFF Interrogator
IFF Transponder
•Altimeter (AL) Radar Systems
•Terrain-Following Radar (TFR) Systems
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6. Automatic Dependent Surveillance-Broadcast (ADS-B)
 Data is broadcast in the form of discrete packets.
 Since the mid-1990s, FAA has focused on two different ADS-B
frequencies-
1. 978 MHz Universal Access Transceiver – used by the General
Aviation (GA).
2. 1090 MHz Extended Squitter (ES) – used by airliners and
other large aircraft.
 The 1090ES is selected for its international interoperability, whereas
the UAT link is for its weather graphics up-link capacity and low cost.
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8. • Accuracy does not seriously degrade with range, atmospheric
conditions, or target altitude.
• Update intervals do not depend on the rotational speed or
reliability of mechanical antennas.
• Accuracy is unaffected by the range to the aircraft.
• Also operable in lower altitudes and mountainous regions.
• Relatively inexpensive technology, with costs for equivalent
radar coverage running in the 0.1 to 0.05 range.
• A single Mode S 1090ES ADS-B ground station can cost
anywhere from $150,000 - $300,000 USD, including
installation.
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9. Mode S 1090ES ADSB Sample Mode S Multilateration and 1090ES ADS-B Ground
and Multilateration Ground Station Installation for FAA ASDE-X Program.
Stations Deployed On Oil
Platforms In Gulf of Mexico For
Helicopter and En Route Tracking 9

10.  Airbus has stated its intent to
begin equipping all new
transport class aircraft it
produces with Mode S 1090ES as
a standard feature.
 UPS, a US freight carrier, is in
the process of installing Mode S
1090ES ADS-B avionics on all
107 Boeing 757s and 767s it
operates.
 Australia, Japan, China and
some parts of Europe & Africa
have also opted for ADS-B and
plan to implement it soon. # Map showing European airports
with ADS-B compatibility
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11.  Essentially a single-node operation scheme.
 Range is limited to the direct transmission range of the airborne Antenna.
 The 1090ES is likely to support ADS-B applications that do not require
air-to-air ranges exceeding 80km when used in the highest density airspace
and will provide ranges of 180 km in lower traffic density airspace. This is
too short for longer range applications and flight-path-conflict resolutions.
 Research is on to implement an airborne ADS-B architecture that will
readily accommodate a second ADS-B link in addition to the 1090ES.
 However, these additions can be too expensive and problematic, especially
when in India, we are yet to realise the full potential benefits of even one
digital link of the single-node system.
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12. Fig illustrates the main drawback of ADS-B
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14.  Multiple-hop means an ad hoc network where the data
exchange is not limited to just a single pair but it includes a
number of nodes.
 The nodes not only transmit their own data but also those
received from neighbouring nodes.
 One aircraft can be made to broadcast not only its own state
information periodically, but also the state information it
receives about neighbouring aircrafts.
 Clusters can be disjoint from, or overlapped with each other.
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15. Fig. shows a cluster of planes forming a multiple hop network
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16.  Possible to select more useful
information over a larger area
for cockpit display and
onboard automation systems.
 Pilot can virtually see other
aircrafts beyond its
transmission range.
 Live data can be sent in a
reliable and timely manner.
 Can provide a collision-free
and extended traffic coverage.
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18.  The transmitted Protocol specifies
The maximum number of hops the state information
will be relayed
How often the state information is broadcast
What state information to broadcast
The mix of own aircraft information vs. information
of other aircraft, etc.
 The protocol should also specify a transmission rate
such that it is ample to handle the data that it receives
and transmits, i.e. the processing rate of the information
should be synchronised with frequency with which data
is received.
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19. Fig shows an example of five node network with link delivery probabilities.
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20. Future Achievability
Extensive research on the following issues is required for future usage :
 Security needs to be dealt with, as the data is open to all receivers.
 A proper protocol needs to be devised which will address the points
mentioned before.
 Testing needs to be done using real-time simulations to test the
effectiveness.
 Issues such as information reachability and effect of signal interference
need testing.
 Priority should also be specified, so that information about the nearest
aircraft is processed first before moving to data from farther aircrafts.
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21. • www.ads-b.com
• www.faa.gov
• www.wikipedia.com
• www.howstuffworks.com
• www.springerlink.com
• www.sciencedirect.com
• M. S. Nolan, “Fundamentals of Air Traffic Control”, 2nd Edition, Wadsworth
Publishing Company.
• J. D. Anderson, “Introduction to Flight”, 4th Edition, McGraw-Hill.
• Charles E. Perkins, “Ad-Hoc Networking”, 1st Edition, Addison and Wesley
Publishing Company.
• “Aviation Today” Magazines.
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