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Concept Paper on
Emergency Communications during Natural Disasters:Infrastructure and Technology
To be carried out by: Broadband Mobile Communications Research Lab (BMCRL),
Asian Institute of Technology, Bangkok, Thailand
Overview of Research Conducted at Present/Expertise: Carrying out research for the
next generation Mobile Communications covering the physical layer aspects, especiallymultiple access techniques, high spectral transmission methods and advanced error
control techniques. The data rates in new mobile networks are expected to be in the range
of 100 Mbps - 1 Gbps. Given the unreliable nature of the mobile channel and different
propagation environments that depend on the carrier frequency, cellular architecture anda host of other factors, there is a strong demand for new methodologies needed in the
physical/Radio layer.
The research conducted is expected to provide detailed analysis of performance for newmultiple access techniques, capacity of multi-user systems, and new transmitter/receiver
configurations for a variety of channels. Multimedia research will look in to new methods
of image/video compression. Transmission of multimedia content over mobile channels
is a challenging task with increased data rates and hostile channel conditions.
In addition, aspects of data security are expected to be addressed as security plays an
increasingly important role. There is a need to investigate new encryption algorithmsgiven the computational powers of present day computers which may lead to attacks oncritical data. More importantly, the development of these algorithms would make sure
that there is sufficient know how is available given the proprietary nature of developed
algorithms.
Context in Disaster Communications:
Disaster Warning:
Here the main principle is to have sufficient lead time so that people can take measure to
prevent or minimize damage. The warning could be provided in terms of a signalappropriately channeled to provide either some visual indication of the impending
disaster or in audible form like sirens. The signal has to come from or generated from
detection equipment (sensors for earth quake, storm, flood, tidal wave or Tsunami). This
then can be picked up by some satellite networks in some dedicated emergency channeland/or through the mobile telephone networks (Base Stations), provided it is sent in the
proper format and then broadcast in an emergency channel. At the signal receiver end,
there should be sufficient identification to differentiate the warning signal. Once
identified, the receiver will then generate the required alarm. The receivers can bedistributed over the warning area (here, the idea is automation. No delay in decision
making or no answer due to holidays etc.).
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In some cases, detection equipment is distributed over different geographic areas. In suchcases, the signals from different areas can be collected using the same transmission
method described above, e.g. the telephone network, to a common receiver who interprets
the data and makes a decision whether or not to generate and broadcast a warning alarm.
The objective here is to identify the modifications needed in the existing communications
architecture and protocols to obtain and transmit the warning signals and the design of thereceivers capable of picking up the signal.
A. Disaster Warning
Proposed Actions
1. Signal generation from detection equipment2. Establishment of methodology for the satellite network to pick up signal3. Set up a procedure for Terrestrial/mobile networks to obtain the signal4. Broadcasting the signal5. Distribution of receivers geographically to obtain the Alarm6. Identification of the warning signal and Alarm generation
After the Disaster:
Disasters can not be prevented. But through proper warnings and disaster-after recoveryprocedures, the effects can be minimized. The collapse of communications infrastructure
is the usual effect of disaster, due to the collapse of antennas, buildings, power etc. But,
immediately after the disaster, due to emergency, communications are vital. There are
two aspects in this scenario. One is to immediately locate the affected persons andprovide emergency assistance. The other is to provide disaster relief during and after the
disaster.
In both scenarios we have to assume that most of the local communication infrastructure
would be unavailable. For example, some base stations may be destroyed.
Therefore the main idea is to look into the following issues in detail and to come up withdetails for suitable implementations.
Tracing of survivors- This can possibly be done assuming the availability of a mobilephone with the person(s) affected. In this case, it may be possible to establish a
communication link using
a) Base stations which are not destroyed - Here the surrounding base stations can beasked to interrogate the mobile stations that they see and provide that information to a
central monitoring station.
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b) In the absence of active base stations, it might be possible to devise a scheme totransfer the local cellular layer to a higher layer, possibly consisting of a satellite.
For this scheme to be possible, layered architectures should be considered. In addition,most important aspect would be how a regular mobile phone could be detected by a
satellite. It is proposed that methodologies for this must be investigated. This may include
having high power emergency channels available in the satellite, add-on extendableantennas for the mobile phone, hardware/software reconfiguration in the mobile etc.
In the cases where adding the satellite feature to each regular mobile phone is tooexpensive, we can consider an alternative network architecture. In this architecture, a
small subset of local users, e.g. police and town officials, carry mobile phones that are
satellite capable. The other mobile phones are modified so that they can communicate
with these satellite capable phones, forming an ad-hoc network when the base stations areall destroyed. This alternative architecture enables cost sharing of the satellite
communication links among multiple users in the same area. In addition, the cost of
modifying a mobile phone to be ad-hoc network capable is expected to be less than the
cost of modifying a phone to be satellite capable.
Tracking: It would be extremely helpful, if the position of the affected persons can be
located. Possibility of location by GPS should be investigated. The underlying
assumption is that the power available in the mobile phone is limited and how thecommunication must be established under adverse conditions.
B. Post-Disaster Communications
Tracing of Survivors
Proposed actions (availability of a mobile)
1. Establishment of a procedure for the surviving Base stations to interrogate mobilestations in the vicinity
2. Collection of those information in a central station3. In the absence of Base stations
Establishment of a procedure for the mobile to be detected by a satelliteOR
Integration of the mobile to a network with satellite capable equipment Ad Hoc Net work
4. Location Identification
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Communications for Emergency Management:
This would be to investigate a last mile wireless high-speed communications system to
support emergency management. The system will utilize surviving network infrastructureto provide network connectivity to emergency management field workers for applications
such as Geographic Information System (GIS) access and audio/video conferencing.
The issues to be looked at are designing the system architecture, developing and/or
integrating radio, link, network, and application-level hardware and software, and
exploring GIS applications. An important element of the work is rapid deployment, so
equipment must be portable, easily configured, and able to access remote databases andGIS engines.
It may be also an opportunity for Radio Local Area Network (RLAN) technology. Lowpower requirements, low cost, portability, point- to-point, point-to-multipoint and
multicast capabilities, coupled with high bandwidth, make RLANs an excellenttechnology for "on- the-spot" emergency communications.
C. Communications for Emergency
Proposed actions
1. Design of a system architecture for integrating surviving infrastructure2. Establishment of a broadband wireless communication system3. Provision of services required for the field workers
Sustainability:
It is expected that this project will generate interest among the authorities dealing in
disaster situations through dissemination of information through website, publications
etc. The lab will therefore can work in long term expertise development in this areawhich can provide the required knowledge to local scenarios.
This will help in attracting good quality students to work in this crucial area as there have
been several large scale disasters recently. The ability to manage communications wouldbe a great advantage to the South/South East Asian Region.
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System Illustrations of Emergency Communications
Pre-Disaster Communications: Disaster Warning
Prior to a disaster, the main function of emergency communications is disaster warning.We outline the main steps in the disaster warning process below.
1. Sensors employed in the field transmit local environmental information at regularintervals to the data processing center. For example, seismic sensors transmit
earthquake related information that can be used for warnings about earthquakes
and/or tsunamis. The communications can be done via wireline, wireless, or satellite
transmission. Fig. 1 illustrates communications from sensors to the data processing
center.
sensor data
processing center
(24-hr monitored)
sensorsin the field
satellite
wireless satellitereceiver
wireline
sensor data
processing center
(24-hr monitored)
sensorsin the field
satellite
wireless satellitereceiver
wireline
Fig. 1: Data transmission from sensors to the processing center
2. The sensor data processing center, which we assume to be monitored by humans 24hours a day, analyzes the sensor data and makes a decision whether or not disaster
warnings should be issued. Note that this decision is done by humans and notautomated.
3. If the decision is to issue warnings, then the warning information will be distributedwith no human involvement beyond the data processing center. The warnings can
reach the individuals in the disaster area via wireless or wireline transmission, or bythe use of visual/sound alarms. Fig. 2 illustrates communications from the data
processing enter to individuals in disaster related areas
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sensor data
processing center
(24-hr monitored)
individuals
wireless(radio,
SMS, etc.)
wireline (cable TV,
Internet, etc.)
visual/soundalarms
relateddisaster
area
satellites
disasterarea
sensor data
processing center
(24-hr monitored)
individuals
wireless(radio,
SMS, etc.)
wireline (cable TV,
Internet, etc.)
visual/soundalarms
relateddisaster
area
satellites
disasterarea
Fig. 2: Transmission of disaster warnings
Our technical contributions will involve how the warnings can be distributed throughexisting communication infrastructure with only slight modifications of the existing
systems, and with no human intervention required. For example, if the warnings are
distributed using SMS messages in cellular systems, we may be able to use the control
channels as communication channels in case of emergency. A part of our study is toinvestigate in detail how to do so.
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Post-Disaster Communications: Disaster Recovery
After the disaster such as an earthquake or tsunamis, we expect that some or all
communication infrastructure in the disaster related areas are destroyed. The main
function of emergency communications is to set up communication networks so thatsurvivors can establish a contact or can be located by the rescue teams through common
electronic devices such as cellular phones.
We outline three possible strategies for setting up emergency communication networks
below.
1. In the case that some base stations of cellular networks remain after the disaster, wecan utilize the remaining base stations. However, for emergency communications, wewill need to change the transmission scheme (e.g. different frequency band, higher
power, etc.) for larger coverage areas. In addition, a local police station may beequipped with a radio base station that can also be used to set up the emergency
network. For emergency communications, the mobile phone units must be able tooperate in the emergency mode with a compatible transmission scheme. Fig. 3
illustrates emergency communications based on surviving base stations from the
cellular phone systems.
(a) before the disaster
basestation
coveragearea
indi-vidual
(a) before the disaster
basestation
coveragearea
indi-vidual
(b) after the disaster
remainingbase station destroyed
basestation
indi-vidual
(b) after the disaster
remainingbase station destroyed
basestation
indi-vidual
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(c) after the disaster with police base station
remaining
basestation
destroyedbasestation
policebase station
indi-vidual
(c) after the disaster with police base station
remaining
basestation
destroyedbasestation
policebase station
indi-vidual
Fig. 3: Emergency network based on the remaining cellular base stations as well as
police base stations, if any.
2. The above strategy based on using the remaining base stations may not be applicablewhen all base stations are destroyed. In this case, one possibility is to use satellitecommunications for each survivor. For this scheme to be possible, a regular mobile
phone needs to be able to communicate with a satellite. The modifications of existing
systems may include having high power emergency channels available in the satellite,
add-on extendable antennas for the mobile phone, and hardware/softwarereconfiguration in the mobile units, and so on. Fig. 4 illustrates emergency
communications based on a direct contact between each survivor and a satellite.
(a) before the disaster
basestation
coveragearea
indi-vidual
(b) after the disaster
destroyedbasestation
indi-vidual
satellite
(a) before the disaster
basestation
coveragearea
indi-vidual
(a) before the disaster
basestation
coveragearea
indi-vidual
(b) after the disaster
destroyedbasestation
indi-vidual
satellite
(b) after the disaster
destroyedbasestation
indi-vidual
satellite
Fig. 4: Emergency network based on direct satellite communications.
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3. In the cases where adding the satellite feature to each regular mobile phone accordingto Fig. 4 is too expensive, we can consider an alternative network architecture. In thisarchitecture, a small subset of local users, e.g. police and rescue officers, carry mobile
phones that are satellite capable. The other mobile phones are modified so that they
can communicate with these satellite capable phones, forming an ad-hoc networkwhen the base stations are all destroyed. Fig. 5 illustrates emergency
communications based on the use of ad-hoc networks.
(a) before the disaster
basestation
coveragearea
indi-vidual
(b) after the disaster
destroyed
basestation
indi-vidual
satellite
satellitelink
ad-hocnetwork
link
(a) before the disaster
basestation
coveragearea
indi-vidual
(b) after the disaster
destroyed
basestation
indi-vidual
satellite
satellitelink
ad-hocnetwork
link
Fig 5: Emergency network based on an ad-hoc network
We note that the above three strategies can be used in conjunction. Below are the lists of
various technical issues as well as their relationships in a flow chart diagram.
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Emergency
Communications
Pre-Disaster (A)Post-Disaster (B)
Warning
Existing System
GPRS
Send MMS, SMS
NewArchitecture
Automated
Methodology for
Connection to Satellite
or Terrestrial Mobile
Warning Signal
Generation
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Format for
Broadcasting
Geographical Distribution of
Receivers
In remote areas existing
sophisticated network cannot
be guaranteed (GPRS,
Computer access)
Identification of the warning
signal and Alarm generation
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Issues under consideration for (A):
Physical/Network Components
Sensors Communication Link establishment under adverse weather
conditions
- typical network connections could become unreliableeasily
Network Architecture of the system Satellite coverage/ Terrestrial coverage Alarm format Channel configuration in Satellites/ mobiles Requirement
of emergency channel
Classification of warning depending on the receiver type Alarm activation
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Post_Disaster
(B)
Use of surviving
Base Stations
Collection of
Information
Detection of
Mobile by satellite
Integration of the
mobile to Ad Hoc
Network
Location
Identification
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Issues under consideration for (B):
Physical/Network Components
Architecture options Hierarchical Organization of Cellular Layers Organization of surviving network in a dynamic situation Mobile Ad Hoc networks Low Power Coding & Modulation Techniques Establishment of Basic Communication Links Establishment of High Speed Communication Links for
Management
Propagation Conditions under adverse conditions Cooperative Network Components (Mobile Stations)
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