A MANET Emergency Communication for Catastrophic Natural Disasters

 

When stricken by a catastrophic natural disaster, emergency rescue operation is very critical to many lives. Many people trapped in the disastrous areas under collapsed buildings or landslides may have a large chance to survive if they are rescued in "Golden 72 Hours". People evacuated from their home jammed in highways or dome shelters need to communicate to each other for various reasons. However, communication systems were usually down due to various reasons. The loss of communication systems made the rescue operation extremely difficult. Many people died before they got a chance to be rescued. This paper analyzes the causes that paralyzed the entire communication systems in Jiji Earthquake and proposes a MANET based emergency communication and information system that can support a large number of rescue volunteers under catastrophic natural disasters.

CHALLENGES AND SYSTEM

Impact of Communication System Crash

 

The impact of communication system crash to the Jiji Earthquake will be presented in this section. Many people trapped in the disastrous areas under collapsed buildings or landslides may have large  chance to survive if they are rescued in 72 hours, called Golden 72 Hour. The loss of communication systems and information system created a big impact to the efficiency of rescue operation.

•  In a catastrophic disaster, regular rescue teams including trained professional rescue squads, police, army, and fire fighters were far from sufficient for the emergency rescue mission.

• Transportation system was paralyzed not only by broken bridges and roads, but also by a large number of disorganized voluntary rescue vehicles

• A large volume of rescue and relief resources were misplaced because the assessment of disasters distribution is virtually blind and inaccurate in the early hours even days after a big quake.

•  Trained and skill-specific professional rescue squads were misplaced to wrong spots

Causes that Crashed Communication

Systems

To many people's surprise, cellular mobile communication systems that were thought highly dependable in emergency were completely wiped out in many cases. Followings are parts of causes we found in Jiji Earthquake:  

• Base stations were crashed.

• Trunks connecting base stations to MSCs were broken almost everywhere, especially broken roads and bridges

•  Backup power generators were out because of fuel exhausted.

•   Critical hardware equipments were down because cooling tower fell down or cooling pipes were broken.

Environmental Constraints and System

Requirements

Following are the constraints and requirements for an emergency communication system that can support a voluntary rescue operation for a catastrophic disaster.

• Outgoing link is either not available or very limited.

• Server is probably not available.

• All Internet based services, such as Skype, are not available, because of no Internet access.

• There is a very stringent time constraint that volunteers are not able to use those devices that have a complicated user interface. In other words, user interface must be very simple.

Available Options of Emergency

Communication Systems

There are few options for emergency communication systems

• Walkie-Talkie Perhaps Walkie-Talkie is the most convenient and reliable communication system for emergency. However, the popularity of Walkie-Talkie in many countries is far less than notebook PCs.

•    Emergency Mobile Communication Systems Various equipment vendors are offering emergency mobile communication systems to stop its momentum yet.

MANET based P2Pnet

To construct a MANET based group communication system to support emergency communication and information network, called P2Pnet. Using P2P communication technologies, a P2Pnet is able to support Walkie-Talkie-like communication, Push-to-Talk, VoIP, and network information systems for emergency usage. Compared with other options, no extra hardware cost is needed.

MANET Based P2Pnet

System Architecture

P2Pnet is a server less peer-to-peer communication network based on MANET to support temporary group communication and information network.  P2Pnet is a serverless peer-to-peer communication network based on MANET to support temporary group communication and information network. As depicted in Fig, some nodes may have satellite communication capability performing gatewayfunctions so that all other nodes can access Internet through gateways if they are available. On top of MANET, there is a layer of peer-to-peer communication service to support higher level services such as Walkie-Talkie, Push-to-Talk, and VoIP communications.

  

Three basic communication modes are supported as followings:

• Uncontrolled Single-Hop Group Communication Network (U1Net) Each node can broadcast data to neighboring nodes in one-hop distance.

•  Uncontrolled K-Hop Group Communication Network Each node can broadcast data to neighboring nodes in K-hop distance. No authorization will be enforced. This mode can support long range Walkie-Talkie-like communications.

• Controlled K-Hop Group Communication Network  This is a more advanced mode and can support unicast type services such as VoIP. 

The most important lessons we learned from numerous disasters are that mobile communication system is vulnerable and the loss of communication system may have a catastrophic consequence. This paper analyzes the causes that paralyzed the entire communication systems in Jiji Earthquake and proposes a P2Pnet that uses notebook PCs to construct a MANET based emergency communication and information system. Brief system requirements and system design are presented. A prototype of Disastrous Earthquake Rescue Information System is presented. Finally, a P2Pnet prototype was tested in and English mobile learning class. The technical aspects of experiment results are presented.

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