Objectives

Module 2 introduces some of the tools available for communication in emergency and disaster situations.  It looks at public networks, and at their characteristics, the operational implications of their use, as well as possible hindrances to their application in different phases of emergencies and disasters.

2.1       Introduction: Using what is available

In module 1 we have established the principle of using what is available. To follow this principle, we shall review the needs as well as the tools. There are various ways to categorize telecommunication equipment and networks: By range, by technology, by application and even by affordability. All these aspects determine their usefulness during the different phases and by the different actors in emergency preparedness and response. New developments in technology have added new dimensions even to conventional means of communication, and have given them multiple roles. The processing of the information transported by telecommunications has become increasingly complex. Consequently, we shall first of all have a look at the characteristics of the existing telecommunication networks, and only then consider their suitability for different tasks within emergency and disaster preparedness and response.

2.2       Public Networks

A public network is a service, provided to the public by a service provider. Operating a public network is a commercial activity.  In the past, public networks were in most cases operated by governments. More recently the government monopoly has in most countries been replaced by a licensing requirement, transferring the responsibility for the functioning of the networks to private enterprises while maintaining government supervision. The importance of public networks for society and the necessity of inter-operability between networks on national as well as international levels require an overall control by a central, usual national authority.

The infrastructure of public networks is vulnerable. In many cases, central elements of more than one telecommunication network are co-located, so that simultaneous disruption of different networks may result from an impact at one single location. [example 2.2.a]

Telephone networks, transmitting not only voice, but also various formats of data such as fax or text messages, and providing public access to other networks, such as the Internet, are the most extensive public networks. They include fixed as well as mobile services.

The conventional fixed telephone network comes to mind first, when a way to transmit an emergency message is needed. It is the common tool to alert emergency service providers. Advanced technology has enhanced its role, allowing the quick and efficient re-direction of emergency calls through one central emergency service (reachable by dialling 911 in the US, 112 in most of Europe) to the appropriate responder. The capability of providing caller identification facilitates the dispatch of assistance. The public telephone network can be expected to be available as long as the possible physical impact of an event does not prevent access to a telephone or disrupts its infrastructure.

Beyond the use as a tool for emergency alert, the value of the public telephone network diminishes rapidly. With the onset of a disaster, overload of the network will make it unavailable even in those cases where the actual physical impact of the event has not damaged or destructed the cable network. It is the nature of the telephone network that for each call a number of installations are involved to establish a link between two points. Failure or overload of any one element along the way, will lead to widespread disruption of traffic. [illustration 2.1]

Two accessories or parts of many fixed-line telephone installations are likely to affect the use of the system in an emergency or disaster situation:

Most of the "Cordless phones", providing mobility within a very short range, typically inside a building or in its immediate vicinity, will not work in case of power failure: The handset operates on batteries, but the base station (connected to the telephone line) usually depends on power from the power line.

A Private Branch Exchange or PBX is a common feature in many offices. When the power line is disrupted, the extensions of such an internal network will no longer work, unless a source of back-up power, such as properly maintained and continuously re-charged accumulators, are installed. At least one telephone set should permanently be connected to the fixed telephone line without passing through a PBX, and everybody should know its location; in case of a local power failure without disruption of the public telephone network, emergency access will be possible to the public telephone network from at least one point.

Priority status for urgent calls could be a way to overcome the overload problems of telephone networks. Giving such priority to subscribers expected to have key functions in case of emergency is technically possible, and has in fact been introduced in some cases. The solution might appear as logical; it has, however, certain drawbacks:

–          We have seen that institutional emergency services are not the only responders in an emergency, and the restrictions any priority scheme imposes on non-priority subscribers may well be counterproductive. Remember: First response is the task and duty of everyone who can help.

–          A priority scheme has to be universal, ensuring end-to-end priority for a call. When more than one network is involved, as this is the case in all international and even many national calls, the rules must be the same for all operators concerned. A priority call must be recognizable as such for all networks concerned.

–          In the attribution of priority status, all service providers must follow the same criteria. Given the tough competition between the commercial network operators, priority-attribution can become a sales-argument. The operator applying a more generous attribution policy is likely to get more clients than the one who has to tell his potential clients that in case of emergency, they will be "thrown off" the network.

The mobile telephone network is based on the same concept of a point-to-point connection between two subscribers. A mobile telephone is nothing more than a wireless extension of the fixed telephone networks. While additional technological factors such as the use of digital rather than analogue modes enhance the functions of a mobile phone, it is still part of the conventional telephone network. In the following we shall consider the most common form of public mobile telephone network, the cellular system. [illustration 2.2]

In a cellular system, radio base stations ensure the link with the subscriber. The range of such a station, and therefore the size of each "cell", depends on topographical conditions. In an open landscape a cell might have a radius of several kilometres, in a dense urban environment one of less than 100 metres. Users can move from one cell to another; calls are handed over automatically whenever a subscriber enters the range of a new cell. Each cell can handle a limited number of simultaneous calls; depending on the expected user density this number is typically between 5 and 50. Each cell needs not only a connection to its access point into the public fixed-line telephone network, but also a supply of electric power. Depending on the location of a base station, the first connection might be provided by fixed line or by a microwave link, and the power might be provided over a cable or by independent means such as batteries charged by solar panels. Agreements among network operators allow the use of mobile phones registered in one network to also function in those of other operators in the same or in another country. In emergency situations, this capability can be of particular value; the cost of calls made or even those received under such "roaming" conditions can however be very high.

Where available, and as long as it is not affected by the impact of an event, the mobile telephone service is an extremely valuable addition to what is available in emergency communications. However: The high investment involved in a wireless infrastructure limits mobile services to locations, in which demand can be expected to be high enough to ensure economical operation. Their dependence on additional infrastructure furthermore adds to the vulnerability of mobile telephones. The number of simultaneous calls in any one location, within the range of any one cell, is in any case limited to the number of calls the operator of the system expects at "normal" times.  [example 2.2.b]

The resistance of cellular telephone networks against the impact of a disaster can often be higher than that of fixed line networks, provided that the relevant issues are taken into consideration when the network is being built. One critical factor is the need for electrical power: Base stations should be equipped with batteries of a capacity sufficient to guarantee longest possible functioning in case of failure of the electricity network.  Individual users should keep batteries and spare batteries for their handsets charged at all time, in order to maintain communication in case of power failure.

A temporary extension of existing or a replacement of damaged networks is often possible by the rapid deployment of so called "cells on wheels (cow)", mobile radio base stations. Depending on its size, such a "cow" can handle a certain number of simultaneous calls. If connection to the public telephone network is not possible locally, a "cow" can even be equipped with its own link or "backhaul", possibly via satellite, to a connection point into the public telephone network. The operators of cellular networks should be involved in the development of emergency communication plans; they have the necessary expertise and they will need to have the necessary equipment ready for rapid deployment.

Early Warning by Mobile Telephone is possible thanks to the unique capability of the cellular system to simultaneously reach all subscribers located within the range of one or more cells. A "cellular alert" text message can be broadcast simultaneously to all mobile phones logged in on a cell, independently of the network they are initially subscribed to. Large numbers of such "roaming" users of mobile phones can be expected in places such as airports or tourist resorts. Individuals receiving such an alert will not only be able to take appropriate action, but they will be able to alert others in turn.

Cellular alerts are a built-in capability of most cellular networks, and all mobile phones have the capability of receiving the messages. Once there is a decision to issue an alert, a computer identifies and the cells covering the area to be alerted. Messages for various situations can be pre-programmed, and will be distributed instantaneously. Cellular alert systems are overload proof, as they use separate data channels existing in all networks, which are not used for actual communications.

The mobile telephone network via satellite is only a further extension of the conventional telephone network. To put it very simply: The "cells" of the mobile network are located on satellites, and their reach is much greater. Consequently, mobile satellite phones can cover the entire globe. And while the number of simultaneous calls each "cell" can handle is of course limited, satellite phones bypass the damaged or overloaded network infrastructure in the vicinity of an event by relaying the calls from a subscriber to an exchange at a ground station far away from the affected location. Different systems of satellite telephones have very different characteristics, and we shall have to come back to the subject in a later module of this course. [illustration 2.3]

Fax and data transmission are additional capabilities offered by the public telephone networks. The equipment used in those modes is by its nature digital. Converting the content of a message into digital signals, into pulses, can greatly increase the amount of information carried over a telecommunication link. The conventional telephone network however is based on the analogue transmission and reception of sound waves, and the advantages of the digital technology are not fully available when additional conversions between digital and analogue signals have to be performed at the transmitting as well as at the receiving end. The functioning of a fax communication depends on the functioning of the public telephone network; the fax is therefore no alternative if in an emergency situation the telephone network becomes unavailable.  The same applies wherever local access to an actual data network, such as the Internet, is provided through a telephone line. [example 2.2.c]

Public Telegraph networks in many countries no longer exist. With the increasing availability of personal access to telecommunications networks, the need for this service has diminished to a point where the maintenance of this separate and very labour-intensive network is often no longer economically feasible. With their disappearance, however, an independent and relatively overload proof telecommunications tool has been lost. Where a telegraph network still exists, its capability to handle emergency traffic should not be overlooked.

The Public Telex network, once a mainstay of international public data communication, has in large parts of the globe gone the same way. The limited speed and the equally limited format of messages transmitted by telex machines restrict the use of this communication mode to special applications, mostly in non-public networks. Once more, a possible alternative to the public telephone network has been lost, but in the same way as the telegraph service, a possibly still available telex service should not be overlooked when it comes to use all means available in an emergency situation.

The Internet has a structure, which is entirely different from that of telephone, telegraph or telex networks. Over the Internet, information is not sent through a single "channel" established between the communicating terminals. Reliability and resistance against disruptions were main purposes the developers had in mind when developing the network we today know as the Internet.  These characteristics were achieved by dividing each message into small pieces, so called "packets", which are being forwarded through computers, called "servers" and "routers", which automatically search for the best available route between the communicating terminals. Doing so continuously, the system also overcomes congestion at least to a large extent: A telephone link is busy also when neither subscriber says a word; the Internet transports only the packets with the actual information. [illustration 2.4] [illustration 2.5]

For more on the structure of the Internet, go to http://www.cybergeography.org/atlas/atlas.html>

The advantages of the Internet as a separate network, and thus as an alternative to other public networks, are of course ensured only for users benefiting of a direct access to it. This is mostly the case for large administrations, enterprises or other institutions. Most private citizens depend on their personal telephone line or on access through the mobile telephone system. The vulnerabilities of these networks will therefore in many cases also affect the public access to the Internet. In a "dial-up" connection, the terminal actually dials the number of the computer serving as the gateway into the Internet. Some protection against overload or disruption of network elements other than the actual subscriber line is provided by technologies using only the subscriber's telephone line as a carrier for the data, linking the user's PC to the nearest access point to the Internet system. Such technologies include DSL and ADSL connections; the actual telephone wire or cable carries the information only to a nearby access point and in a mode that does not interfere with the normal analogue audio signals used in the telephone service. We will have to look at more details of the technologies when we consider the technical aspects of various emergency telecommunication modes in a later module.

The Internet also allows communication by voice ("Voice over IP" or VOIP). A VOIP link works like a telephone call, and some service providers even provide the possibility of connections into the public telephone network. VOIP can be useful in situations where the telephone network is disrupted or overloaded, provided the link from subscriber to service provider still functions. Concerning the use of VOIP for emergency calls however, it is important to know, that certain capabilities of the telephone network are not available via the Internet; this includes the caller identification providing emergency responders with automatic information about the origin of an emergency call.

Pagers or "Beepers" are one-way communication tools. They can transmit an alert, but the amount of information they can handle is very limited. These characteristics make them overload proof, but limit their application in emergency telecommunications to the alert phase - pagers can transmit a "cry for help" or issue an alert, but they can not provide the dialogue necessary in all later phases of an emergency operation. Some pager systems have public access; others are operated for specific purposes of a closed group of people.

Broadcast is another example of a public one-way communication. The volume of information a broadcast system can distribute is limited only by the speed in which information can be obtained and absorbed. In the alert phase, broadcast is a most valuable tool. To the degree that receiving equipment and the power needed for the operation of such equipment remain available, all forms of broadcast maintain this role even in the aftermath of the impact of a disaster.  The most common forms of broadcast are of course radio and television, but also other systems have broadcasting capabilities, which can be used in emergency telecommunications. We shall come back to one such option when we talk about communication modes in a later module of this course.

2.3       Some Common Aspects of Public Networks

We shall have to consider the regulatory environment of telecommunications in more detail in the fifth module of this course. Looking at the use of public networks in emergency telecommunication, we nevertheless need to be aware of some implications already at this time.

In all countries, the provision of a public telecommunication service is subject to government regulation. Public networks are not under the direct control of the actual users. In an emergency situation, the usefulness of telecommunication networks with direct access for the public is thus determined by the network operators and ultimately by government authorities.

Telecommunication costs can easily become a very heavy burden for the providers of disaster relief. While cost might be considered as a secondary issue during initial, life-saving operations, it can, even within a few days, go well beyond the budget, in particular that of non-governmental, voluntary organizations. On top of the list are here of course satellite links, where the fees even for short calls can be prohibitive in particular for calls between two satellite phones. In most systems, such a call is being billed as two calls; for technical reasons it is routed from the caller to the satellite, from there to the ground station, and then again up to the satellite and down to the other satellite phone.

There have been several attempts to obtain a general reduction in telecommunication fees during the acute phase of disaster relief operations. An international treaty, the "Tampere Convention", about which we will learn more in a later module, stipulates that fees should be reduced in such situations. So far, mostly the multitude of network operators and the complexity of the international billing systems have been given as the reasons for the lack of implementation of the respective article of this international treaty.

To an increasing degree, providers of public telecommunication services give consideration to the disaster-resistance of their networks. However, it has also occurred that in a disaster situation public access was intentionally restricted. In the past there have been two reasons for such non-technical restrictions: Pre-emptive priority schemes, allowing only communication between pre-defined subscribers such as authorities and emergency services, and intentional disconnection of communication links in case of crises with political or military implications [example 2.3].

The fact, that even the infrastructure of telecommunication within one country is not necessarily under the full control of its national authorities, adds to the risk of "administrative disruptions" of services.  This applies in particular to satellite links, as even a call from one satellite hone or terminal to a counterpart under the same national jurisdiction has to pass through a satellite and usually also involves a ground station in a foreign country. The operator of the satellite network or the owner of the infrastructure may, at any time, discontinue access for certain regions or individual subscribers.

Very few cases of intentional, administrative disruption of services have occurred so far. Restrictions, or even prohibition of the use of satellite phones and terminals, however, have occurred in conflict situations. In comparison to terrestrial telecommunication links, satellite services have in any case additional vulnerabilities and can therefore not be relied on as a universal solution for emergency telecommunications.

Broadcasting is the most public form of telecommunication over a public network. It is a very powerful tool of public information, and many countries therefore exercise strict control over it. Such control commonly involves not only the telecommunication authorities, but also other government entities dealing with public information, the media, as well as public safety and security.

Broadcasting information through any medium, radio, television, cellular phones or even loudspeakers can have a very massive impact on the behaviour of the recipients. In an emergency situation it is therefore most important, that information is reliable. Establishing clear rules for the authorization of emergency messages can ensure this. Guidelines and rules for the processing of warnings or other advice to the public must be part of any disaster preparedness plan. At the same time it can be vital, that warnings will not suffer delay by the need for authorization by an authority, which might just in a time-critical situation not be immediately available.

2.4       Some Conclusions

Public networks are in most cases the first emergency telecommunication tools available. Their resistance to infrastructure damage and in particular to overload is however very limited. They are not under the full control of the users, and subject to a number of outside, possibly foreign, influences. Beyond the immediate, most acute and life-saving phase of disaster response, their use, in particular for international communication, can be prohibitive.

Response to an emergency will therefore always require the use of additional, specialized means of communications. These "private networks" shall be the topic of the next module of this course.