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Cellular radio
THE C O M P U T E R L A W A N D S E C U R I T Y REPORT
5 CLSR
calculations. The standing order clerk would find it much more satisfactory to be able to 'set-up' new standing orders on the screen, instead of by filling in forms so that someone else can key in the data. The securities staff would find their lives easier if they were able to obtain up-to-date valuations of share portfolios on the screen, or enquire as to what property was charged to the bank as security for an advance. The foreign department would find they could provide a more efficient service if they were able to obtain current foreign exchange market rates without having to make a telephone call. All departments would benefit if transations were to be entered on the computer as they arise. These are the sorts of developments at branch level in banks' computer systems which are being and will be considered by the banking industry, all of which are aimed at providing a better service for customers. The next logical stage would be for enquiry
terminals to be made available in banking halls for the Use of customers to enable them to check the status of their accounts, and to initiate some types of transaction. But that step is probably still some way off. The next two articles in this series are concerned with the exploitation of technological advance in ways which are largely transparent to customers: the automation of the paper Town Clearing in the City of London by the introduction of CHAPS (Clearing House Automated Payments System); and the concepts of cheque truncation. The final two articles deal with services which will impact banks' customers much more directly; Point-of-Sale payment serices; and Home Banking,
John Reilton Adviser, The Committee of London and Scottish Bankers
TECHNOLOGY UPDATE CELLULAR RADIO 'Technology Update' is a new series designed to give an overview of the underlying technology used in the Information Technology field and the services that are based upon them. It will focus on those technotogies which give rise to legal and security issues resulting from their use. The first articles in the.series will concentrate on the area of data communications and the various methods that are currently and potentially available along with the accompanying problems of transborder data flow and the means of keeping data communications secure. Later, areas such as chip fabrication will be explored and the problems that arise in the protection of the design.
by international convention, a 'frequency famine' has developed. This has been a considerable impediment to the development of the mobile communications market place. Successive technological developments have reduced the band of frequencies required to carry a conversation by almost two thirds, but this has been rapidly overtaken each time by demand. A second problem facing the mobile communications user is the power of transmitters and receivers. To achieve communications over a long distance the transmitters need to be powerful, which in turn means that they are expensive to run - especially given their energy demands. Equally, they are still subject to the interference caused by the natural contours of the land.
UNSATISFIED NEEDS
THE DEVELOPMENT OF CELLULAR RADIO
The concept of cellular radio arises out of a growing demand to provide communications with a moving location. Whilst, at one time, this was almost exclusively restricted to the emergency services it now has a strong base in the commercial world. The basic technique is to use radio communication. Mobile radio has been in use for many years and its integration with the telephone system through the use of mobile telephones has been long established. Unfortunately the systems are expensive to run and are limited in their capability, but despite this the demand for such services has grown substantially. The speed with which Citizens Band Radio (CB) has been adopted in this country is evidence of this large, unsatisfied demand. However, CB illustrates some of the basic problems associated with the use of radio as a medium for private two-way communications. It is inherently insecure and poses the greatest difficulty in preventing eavesdropping on conversations or their unwanted interruption by a third party. This arises from the broadcast nature of the transmission, the need to use known frequencies and the limited number of frequencies available. With the growth in demand and the limited number of frequencies, whose allocation is governed
One approach to overcome some of these drawbacks that has recently come into the UK marketplace is the concept of cellular radio - a technology developed by AT Et T's Bell Laboratories in the USA. It looks at one nationwide approach to the problem instead of a multitude of local solutions. The whole country is divided into cells, rather like a honeycombe on a geographical/population density basis. Each cell has its own transmitter/receiver (transceiver) which operates on a specific set of frequencies for the communications being made within the cell. Adjoining cells operate on different frequencies thus avoiding interference between cells. As a user moves from one cell to the next the frequencies are automatically changed under the control of a computeL Transceivers are linked into the public switched telephone network (PSTN) and are linked to one another through land-lines. Thus, one caller using cellular radio can call another user anywhere within the cellular network or any telephone user. The User is unaware of the cells changing as they are traversed. Each cell covers an area from about half a mile across in the centre of an urban area to possibly ten miles across in a rural area. One major attraction of this approach is
18
THE COMPUTER L A W AND SECURITY REPORT
J A N U A R Y - FEBRUARY
that frequencies can be re-used across the country provided the buffer cells, operating at differing frequencies, separate the cells operating at the same frequencies. With this'honeycombe' structure the cell can be thought of as roughly hexagonal in shape. Each cell is surrounded by six or seven neighbours and this pattern can be repeated. Thus only seven or eight sets of frequencies are required for the pattern to be repeated over a large area. To begin with there are 400 separate frequencies being used by cellular radio split equally between two operators. Given the need to define six or seven bands of frequencies, to avoid clashes between neighbouring cells, this gives 30 frequencies and hence 30 simultaneous calls in each cell. This communications infrastructure is closely linked to the public telephone network and opens up all the services that are available over the PSTN. Thus, an added attraction of cellular radio is its integration with existing wide area communications facilities.
must be bought exclusively for one or other of the systems, but users on different networks can talk to each other via the telephone network, Under the terms of the licences, the two networks are supposed to move towards complete compatibility with one another. The investment has been substantial for the two consortia involved with estimates as hioh as £100m for the final figure for each of them. Usage costs reflect this with the costs for CELLNET typically being £60 per month registration fee, £25 per quarter rental and 25p per quarter rental and 25p per minute for calls at peak time. Mobile phones cost between £ 1 0 0 0 - £ 2 0 0 0 to buy. It is expected that the cost will fall dramatically as the number of subscribers increases.
FUTURE PLANS There appears to be some excitement in what the future holds for the transmission of data over cellular radio. Given this sort of facility the user wil! be given access to such services as PRESTEL or other Value Added Network Services that are introduced via the PSTN. Many suppliers are developing products, such as modems and data terminals, which will work to cellular radio standards and these open up the prospect of connecting Cellular radio to personal computers. There are some problems in the transmission of data in this way. One problem occurs as the user is transferred from one cell to another. This causes a break in communications for a short space of time, typically a quarter of a second. Although in a voice transmission this is not noticeable, in data transmission this could mean a significant loss of data, Thus, special protocols need to be devised to overcome this sort of problem. RACAL VODAFON E have already announced just such a protocol - Cellular Data Link Control. Given this sort of development there seems to be no mason why the cellular radio market should not explode. Taxis are being evaluated as possible providers of cellular radio communications for their customers and a recent announcement by BT that the Telecom Gold electronic mail service is now available over CELLNET means that the services are being marketed in a very vigorous way by all concerned. It seems likely that before long, the rather arbitrary distinction between mobile and home/office telephone will be a thing of the past.
RAPID EXPANSION The development of cellular radio has been dramatic. Well etablished services have existed in the United States of America and in Scandinavia for a number of years. The first moves in the UK to establish a cellular radio service were made in 1982 when the Department of Industry announced the award of licences to run commercial cellular radio services after long discussions with the communications industry. Licences were granted to two consortia - one to British Telecorn/ Securicor called CELLNET (previously known as SECTEL) and the other to Racal/Millicom known as RACAL VODAFONE. The licences stipulated a start date of January 1984 and required 90% of the pol~Jlation to be covered by cellular radio by the end of the decade. Both Licences opted to use TACS (Total Access Communications System) which is a development of the AMPS system used in the USA, instead of NMT (Nordic Mobile Telephone) used by Denmark, Finland, Norway and Sweden (and also committed to by Spain, Austria," Belgium, Ireland and the Netherlands). The service has a grown apace since its January start date. By November 1985 both licencees were claiming faster than expected market penetration. The licenceas themselves are not permitted to sell products to the user directly but asociated companies have been set up which sell the equipment either directly or through appointed retailers. At the moment the equipment
Andrew Schulkins
i
NEWS HIGHLIGHTS ill
ill
_
i
i
SPECIAL REPORT ON A T M FRAUD D O W N UNDER
i
ATM fraud poses no significant problem because, in any event, the system also imposes a modest daily withdrawal limit, and an overdrawn account would be closed down within a very short space of time. In Australia the false assumptions present in this chain of logic have been aptly demonstrated in a case in which charges have been made against a 16 year old youth who allegedly defrauded one particular building society, the Hotham, of A$ 40,000 last July.
According to the anonymous author of 'The Hackers Handbook" the only frauds that have been perpetrated on Automated Teller Machines have consisted of overriding the restrictions built into the ATMs software to prevent the customer overdrawing his account. (There may have been other types of fraud, but if there have they have been well concealed from the press.) The conclusion to be drawn from that information is that 19
5 CLSR
calculations. The standing order clerk would find it much more satisfactory to be able to 'set-up' new standing orders on the screen, instead of by filling in forms so that someone else can key in the data. The securities staff would find their lives easier if they were able to obtain up-to-date valuations of share portfolios on the screen, or enquire as to what property was charged to the bank as security for an advance. The foreign department would find they could provide a more efficient service if they were able to obtain current foreign exchange market rates without having to make a telephone call. All departments would benefit if transations were to be entered on the computer as they arise. These are the sorts of developments at branch level in banks' computer systems which are being and will be considered by the banking industry, all of which are aimed at providing a better service for customers. The next logical stage would be for enquiry
terminals to be made available in banking halls for the Use of customers to enable them to check the status of their accounts, and to initiate some types of transaction. But that step is probably still some way off. The next two articles in this series are concerned with the exploitation of technological advance in ways which are largely transparent to customers: the automation of the paper Town Clearing in the City of London by the introduction of CHAPS (Clearing House Automated Payments System); and the concepts of cheque truncation. The final two articles deal with services which will impact banks' customers much more directly; Point-of-Sale payment serices; and Home Banking,
John Reilton Adviser, The Committee of London and Scottish Bankers
TECHNOLOGY UPDATE CELLULAR RADIO 'Technology Update' is a new series designed to give an overview of the underlying technology used in the Information Technology field and the services that are based upon them. It will focus on those technotogies which give rise to legal and security issues resulting from their use. The first articles in the.series will concentrate on the area of data communications and the various methods that are currently and potentially available along with the accompanying problems of transborder data flow and the means of keeping data communications secure. Later, areas such as chip fabrication will be explored and the problems that arise in the protection of the design.
by international convention, a 'frequency famine' has developed. This has been a considerable impediment to the development of the mobile communications market place. Successive technological developments have reduced the band of frequencies required to carry a conversation by almost two thirds, but this has been rapidly overtaken each time by demand. A second problem facing the mobile communications user is the power of transmitters and receivers. To achieve communications over a long distance the transmitters need to be powerful, which in turn means that they are expensive to run - especially given their energy demands. Equally, they are still subject to the interference caused by the natural contours of the land.
UNSATISFIED NEEDS
THE DEVELOPMENT OF CELLULAR RADIO
The concept of cellular radio arises out of a growing demand to provide communications with a moving location. Whilst, at one time, this was almost exclusively restricted to the emergency services it now has a strong base in the commercial world. The basic technique is to use radio communication. Mobile radio has been in use for many years and its integration with the telephone system through the use of mobile telephones has been long established. Unfortunately the systems are expensive to run and are limited in their capability, but despite this the demand for such services has grown substantially. The speed with which Citizens Band Radio (CB) has been adopted in this country is evidence of this large, unsatisfied demand. However, CB illustrates some of the basic problems associated with the use of radio as a medium for private two-way communications. It is inherently insecure and poses the greatest difficulty in preventing eavesdropping on conversations or their unwanted interruption by a third party. This arises from the broadcast nature of the transmission, the need to use known frequencies and the limited number of frequencies available. With the growth in demand and the limited number of frequencies, whose allocation is governed
One approach to overcome some of these drawbacks that has recently come into the UK marketplace is the concept of cellular radio - a technology developed by AT Et T's Bell Laboratories in the USA. It looks at one nationwide approach to the problem instead of a multitude of local solutions. The whole country is divided into cells, rather like a honeycombe on a geographical/population density basis. Each cell has its own transmitter/receiver (transceiver) which operates on a specific set of frequencies for the communications being made within the cell. Adjoining cells operate on different frequencies thus avoiding interference between cells. As a user moves from one cell to the next the frequencies are automatically changed under the control of a computeL Transceivers are linked into the public switched telephone network (PSTN) and are linked to one another through land-lines. Thus, one caller using cellular radio can call another user anywhere within the cellular network or any telephone user. The User is unaware of the cells changing as they are traversed. Each cell covers an area from about half a mile across in the centre of an urban area to possibly ten miles across in a rural area. One major attraction of this approach is
18
THE COMPUTER L A W AND SECURITY REPORT
J A N U A R Y - FEBRUARY
that frequencies can be re-used across the country provided the buffer cells, operating at differing frequencies, separate the cells operating at the same frequencies. With this'honeycombe' structure the cell can be thought of as roughly hexagonal in shape. Each cell is surrounded by six or seven neighbours and this pattern can be repeated. Thus only seven or eight sets of frequencies are required for the pattern to be repeated over a large area. To begin with there are 400 separate frequencies being used by cellular radio split equally between two operators. Given the need to define six or seven bands of frequencies, to avoid clashes between neighbouring cells, this gives 30 frequencies and hence 30 simultaneous calls in each cell. This communications infrastructure is closely linked to the public telephone network and opens up all the services that are available over the PSTN. Thus, an added attraction of cellular radio is its integration with existing wide area communications facilities.
must be bought exclusively for one or other of the systems, but users on different networks can talk to each other via the telephone network, Under the terms of the licences, the two networks are supposed to move towards complete compatibility with one another. The investment has been substantial for the two consortia involved with estimates as hioh as £100m for the final figure for each of them. Usage costs reflect this with the costs for CELLNET typically being £60 per month registration fee, £25 per quarter rental and 25p per quarter rental and 25p per minute for calls at peak time. Mobile phones cost between £ 1 0 0 0 - £ 2 0 0 0 to buy. It is expected that the cost will fall dramatically as the number of subscribers increases.
FUTURE PLANS There appears to be some excitement in what the future holds for the transmission of data over cellular radio. Given this sort of facility the user wil! be given access to such services as PRESTEL or other Value Added Network Services that are introduced via the PSTN. Many suppliers are developing products, such as modems and data terminals, which will work to cellular radio standards and these open up the prospect of connecting Cellular radio to personal computers. There are some problems in the transmission of data in this way. One problem occurs as the user is transferred from one cell to another. This causes a break in communications for a short space of time, typically a quarter of a second. Although in a voice transmission this is not noticeable, in data transmission this could mean a significant loss of data, Thus, special protocols need to be devised to overcome this sort of problem. RACAL VODAFON E have already announced just such a protocol - Cellular Data Link Control. Given this sort of development there seems to be no mason why the cellular radio market should not explode. Taxis are being evaluated as possible providers of cellular radio communications for their customers and a recent announcement by BT that the Telecom Gold electronic mail service is now available over CELLNET means that the services are being marketed in a very vigorous way by all concerned. It seems likely that before long, the rather arbitrary distinction between mobile and home/office telephone will be a thing of the past.
RAPID EXPANSION The development of cellular radio has been dramatic. Well etablished services have existed in the United States of America and in Scandinavia for a number of years. The first moves in the UK to establish a cellular radio service were made in 1982 when the Department of Industry announced the award of licences to run commercial cellular radio services after long discussions with the communications industry. Licences were granted to two consortia - one to British Telecorn/ Securicor called CELLNET (previously known as SECTEL) and the other to Racal/Millicom known as RACAL VODAFONE. The licences stipulated a start date of January 1984 and required 90% of the pol~Jlation to be covered by cellular radio by the end of the decade. Both Licences opted to use TACS (Total Access Communications System) which is a development of the AMPS system used in the USA, instead of NMT (Nordic Mobile Telephone) used by Denmark, Finland, Norway and Sweden (and also committed to by Spain, Austria," Belgium, Ireland and the Netherlands). The service has a grown apace since its January start date. By November 1985 both licencees were claiming faster than expected market penetration. The licenceas themselves are not permitted to sell products to the user directly but asociated companies have been set up which sell the equipment either directly or through appointed retailers. At the moment the equipment
Andrew Schulkins
i
NEWS HIGHLIGHTS ill
ill
_
i
i
SPECIAL REPORT ON A T M FRAUD D O W N UNDER
i
ATM fraud poses no significant problem because, in any event, the system also imposes a modest daily withdrawal limit, and an overdrawn account would be closed down within a very short space of time. In Australia the false assumptions present in this chain of logic have been aptly demonstrated in a case in which charges have been made against a 16 year old youth who allegedly defrauded one particular building society, the Hotham, of A$ 40,000 last July.
According to the anonymous author of 'The Hackers Handbook" the only frauds that have been perpetrated on Automated Teller Machines have consisted of overriding the restrictions built into the ATMs software to prevent the customer overdrawing his account. (There may have been other types of fraud, but if there have they have been well concealed from the press.) The conclusion to be drawn from that information is that 19