Paging or Mobile?

Ivan Nedvídek

At the beginning of the 1960s, the public in the United States, Japan and some developed European countries began to come into contact with a new phenomenon growth of interest in communications with mobile participants. In addition to the relatively awkward radio-telephone units of the time, services and products like paging and radio-contact services aimed at locating and contacting a person started coming into public use. New radio-contact services acquired larger and larger popularity, especially with the expansion of HW offers and their applications. By the beginning of the 90s, these services had achieved greater penetration outside of Europe than cellular telephone services.

Currently, however, the paging picture is somewhat more complicated and the future seems to be less clear than two or three years ago. What were originally clear prognoses for long-term, significant growth in user bases until at least the year 2000 were replaced by more conservative forecasts. These continue to attach relative importance to paging, but are more apt to take into consideration software systems and applications than simple demand for one-way communication, which is influenced more and more by the massive entrance of public digital systems for two-way mobile communication.

Radio-paging Principles and Methods

The ancient ancestor of contemporary radio-paging (which, incidentally, still lives) utilised simple methods in order to function. It made do with one person accepting messages who, in hotel receptions, halls, cafés or restaurants, posted or wrote the message (usually the name of the guest who then reported to reception) on a portable board which was carried by a waiter among tables so that all could notice it. We see a similar sysem in use at airports when expecting a guest we#ve never met. As is now generally known, paging aside from the basic principle of one-way transmission and the name of the service has little in common with its ancestors from an organisational and infrastructure point of view. See Figure 1.

This basic, simple schematic describes, in principle, the infrastructure of One-Way paging, which can be organised to satisfy the size demand of a network and its services. For our purposes, this means local, regional or widearea paging, providing a qualitatively defined type of service.

Local paging (public) is generally understood to be a service for a given area - e. g. part of a city or an entire city.

Regional paging (public) comes from a larger paging service covering a territorial unit which might be a city agglomerate or a specific geographically or administratively bounded area.

Widearea paging is characterised as covering important parts of a large territory (country). As a rule, this refers to places with a high population density or places otherwise commercially or economically significant. In the case of so-called nationwide paging, it#s possible to differentiate between the percent of "population covered" and the percent of "territory covered." The majority of operators of paging services in developed countries do not further specify the concept of paging-services coverage, and provide figures for the percent of a population which has a dependable paging signal in the place of its permanent residence.

The types of paging and additional services are expressed from a qualitative viewpoint and generally refer to the following:
  1. Acoustic paging services, i.e. "Tone only" or "Tone Voice". A message is announce a by a beeping and an illuminated LED indicates whom it necessary to phone or in some way attend to (e.g. red may mean call the office; yellow, call home; green, return to the worksite immediately.) With Tone Voice systems, the pager gives a brief spoken message.

  2. Numerical paging: The message is announced acoustically or by light or vibration, and the panel displays a series of numbers either a return telephone number or a coded notification.

  3. Alphanumerical paging: The message is announced acoustically, by light or vibration, and appears on the display. The maximum length of a message is usually between 40 and 80 characters, while some updated models allow for messages of up to 400 "characters." Currently, 80 "characters" is the standard.
All modern, commercial-use paging systems offer other services which either try to partly eliminate the disadvantages of one-way information transmission or to increase user comfort. Two of the more common services of this type are "Mail Box" and "Voice Mail."

Public radio-contact services must be organised in conjunction with demands for easy public access to this service and its use. This is why basic access is always made available through the public telephone network on a level corresponding to the territorial dimensions of the service.

Further access is made possible by public and non-public data networks, leased stationary channels, etc. See Figure 2.

A message generated by a paging centre within the proper protocol or format must be sent to the transmission site. This data transmission is ensured by a distribution-transmission network which can utilise all appropriate transmission systems for this purpose. Mostly satellite systems are now used to distribute paging data designated for transmission within given territorial bounds.

Transmitting paging data in the form of a message is carried out by means of a transmission network the most widely variable system of the paging infrastructure. Its composition is subordinate to the concrete demands of not only paging systems, but the morphology of the territory, the influence of other telecommunication structures, etc.

How does the transfer of paging information actually take place? We#ll assume that Person A is radio-contact service user who has with him a receiver (customarily called an operátor in this country), and is moving around somewhere in the Czech or Slovak Republics. Person B needs to contact Person A, either by transmitting some sort of message, or by sending his own telephone number so that Person A can immediately call this number. The simplest option for Person B is to use a normal telephone and call a long-series telephone number for a radio-contact centre either 0600111 or 0800000 where he is immediately put in touch with a switchboard operator. Person B informs the switchboard operator of the six-digit calling number of Person A#s receiving unit (operátor) and leaves the message he wants to send. The conversation lasts, on average, a few seconds, and after its completion, Person A receives the message, announced by a beeping, vibration or lights (or a combination of these), and it is displayed on his receiver (operátor).

If Person B has a telephone unit at his disposal that is tone-selection capable and wants to send only a numbered message (e.g. his telephone number), it is not necessary to send out this message through a switchboard operator. The message is sent out by using so-called automatic access. Person B calls telephone number 0600112 or 0800001 and is greeted by a pleasant woman#s voice which asks him to select the number of the party he is calling (Person A) and then to select the following message (by using buttons on the telephone unit). After the message#s accuracy is confirmed, it is immediately sent out.

For those who use the OPERATOR system a lot, especially for dispatching purposes, the "paging by modem" system is advantageous. Access to this service is again provided by a converted public telephone system through a PC and a suitable TAP type modem. This type of modem enables the actual PC to be used as a paging centre departmental terminal for sending out alphanumeric messages manually. It can also be used to automatically transfer paging information for various applications (warning, regulatory, etc.).

Radio-contact Systems and the Most Widespread Protocols.

With the expansion of radio-contact services as a commercial system for one-way communication, it was necessary to establish a system of technical rules which would enable manufacturers and operators to effectively control the form, format and data content of information flow among individual systems. The ultimate goal of this was to produce, offer and operate in the least expensive way possible.

For this reason and also because of standardisation pressures, several systems and standards were established that currently govern the world radio-contact services market. In the United States, those systems are GOLAY, POCSAG and RDS or RDBS. In the Asian Pacific area, POCSAG; in Europe, POCSAG, RDS and MBS; in Latin America POCSAG and RDS (RDBS). The growing popularity of these systems and the demands placed on size, quality and capacity of networks and services provided, however, are leading to further system consolidation and orientation toward higher transmission speeds. In the United States, the FLEX and APOC systems are beginning to come into use, while Europe is already building a national network for the future pan-European ERMES system. This system will be a parallel to the GSM pan-European mobile telephone system.

These "quick digital systems" could even be upgraded to "two-way versions", i.e. they would offer prompt reaction to news or messages sent. This would represent another qualitative step, making radio-contact services which will always be cheaper than radio-telephone services an even more attractive offer.

We will now shrink our scope from the wide offering of systems operating to focus our attention, from a technical standpoint, on the formats which will most likely be dominant in Europe in the immediate and long-term future.

ERMES Format
(European Radio Message Standard)

This new European paging standard is the result of the efforts of ETSI (European Telecommunications Standards Institute) and offers European users (among others) new possibilities that present standards don#t provide. It will spur further interest in paging which, with "ERMES realisation" will bring not only standardisation and simplified technology, but most likely lower prices and simple international use, assuming that the system is widely accepted across all of Europe.

When the system is installed in accordance with its original aims, it will cover more than 320 million residents from all developed European countries; it is assumed that future growth will occur.

In January of 1990, 26 operators from 16 European countries signed the Memorandum of Understanding (MoU) expressing agreement with the creation of new Europe-wide paging services founded on use of the ERMES standard. All signatories agreed to reserve a frequency range between 169.4 and 169.8 MHz for this purpose and to co-ordinate the appropriate frequency channels for all participants of a given country. ERMES is a system which should include not only paging operators, but also manufacturers of receivers. This means that a completely new operating-production standard in the area of paging services would be created.

This paging format with a transmission speed of 6,250 bit/sec. uses a 4 PAM/FM modulation mechanism (Four Level Pulse Amplitude Modulated/FM) which makes up the basic technical parameters for the desired high-participant capacity of the system. The ERMES standard model is more complicated than older coded formats and includes a "scanning" system stretching across all 16 frequency channels reserved for operating in the 169.4 - 169.8 MHz belt.

The ERMES model divides each hour into 60 cycles, each of which is further divided into 5 subsequences of 12 seconds each. This 12-second period of one subsequence contains 16 doses (groups; the original term is batch).

These doses and the corresponding subsequences and cycles of each transmission are coded into the system information parts of the dose, which is an important element of an internationally used system (roaming). The 16 doses, labelled A through P, are progressively sent across the 16 channels of the system in the following manner: dose A is the first dose on channel no. 1, while at the same time, the 16th dose is sent on channel 2. The second dose goes to channel no. 3 while the 15th dose goes to channel no. 4, and so on. This methodology allows the receiver to progress across all frequency channels without losing the message.

From an energy conservation viewpoint, the receiver is constructed so that is becomes activated by one specific dose. The receiver may also be programmed to be activated only by messages in an appropriate subfrequency or even in a specific cycle. Characteristic Features of the System
RDS Format
(Radio Data System)

RDS format, like its predecessor, MBS format, was developed for use in FM VKV radio networks with the goal of ensuring data-information transmission by using subcarrier airwaves in a format which will become a European standard. As opposed to MBS, RDS format wasn#t established only for paging services, but also for transmitting other information which is normally accompanied by specific broadcast programs. Paging is only one of the RDS-format services, though, from a user standpoint, definitely one of the most interesting. The RDS format enables all main types of paging services to be offered: RDS data transmission works at a transmission speed of 1187.5 bit/sec. in the FM VKV II belt, i.e. 87.5 to 108 MHz. Data information is transferred by means of so-called "groups," each of which contains 4 blocks of 26 bits. 16 bits make up an information word; 10 bits a control figure. According to the contents of individual parts of individual blocks, the appropriate groups of which there are two versions (A and B) are defined. The current effective standard CENELEC has 11 groups, of which 6 are defined in versions A and B. For RDS paging, only groups 1A, 4A and 7A are in current use, while 7A transfers its own paging information. If RDS-format paging is located in the FM VKV network broadcasting nationwide radio programs, it can, by relatively simple means, achieve a level of coverage which other paging systems have difficulty in attaining. The main advantage of RDS paging is the possibility for widearea coverage which, given certain conditions, may approach absolute coverage (100% territorial, 100% population).

Characteristic Features: In view of its characteristic properties, this system is destined mainly for the professional market, to which it can provide exactly that which it is missing absolute coverage and sufficient dependability.

What will European paging look like in the near future? Above all, radio-contact services will not be in the position of competitor to GSM and PCN operators. Rather, they will be a useful and hassle-free addition to the basic system of mobile telephone communication. Aside from normal person-contact and delivery of messages and codes, it will offer its users various information services important for their professions and hobbies. Stock information, world currency rates, entrepreneurial information and Internet and E-mail are just a few of the new types of services that paging-services operators will routinely provide. Participants can also have the results of their favourite club, weather forecasts, important political information, betting information, etc., at their prompt disposal. All of this will be in a form which, during reception of news, doesn#t require any active participation or hassle, and which actually enables processing of this data at the most suitable time. The larger volume of this data requires larger system capacity founded on "quicker" formats and protocols.

News and information should be at participants# disposable practically everywhere. This means that, as opposed to the originally expanded and routine regional or city coverage, this offer will be directed toward nationwide services, or on an international level (roaming).

Popular, but limited in possibilities by its format, POCSAG will gradually be replaced in Europe by the ERMES system, which will create the technological base for paging communication and related services at national and international operating levels. If we assume the gradual integration process of European countries and suitable pricing policies which react to the needs and expectations of customers, the Europe-wide system will surely play a dominant role in telecommunications. GSM is such a system in the area of telephone communication, as is the general Europe-wide ERMES system in the area of radio-contact services and RDS for the related needs of professionals.

The Czech Radio-contact Market

At the present time, there is only one operator on the paging market in the Czech and Slovak Republics Radiokontact OPERATOR a.s., which operates a public paging network. It offers complete comprehensive paging and supplementary services, provided with a view toward the offerings and quality of a telecommunications (primarily the PSTN) network.

Participants and callers have at their disposal:

All of these are provided at a regional, republic-wide and international (former CSFR) level.

The OPERATOR service currently serves more than 16,000 OPERATOR receivers which enable owners to be reached on more than 94% of the territory of the Czech Republic. This means that more than 99% of the population of the Czech Republic has the opportunity to receive OPERATOR signals in its place of permanent residence. Coverage expansion will continue ­ its goal is to cover nearly 100% of the country#s territory for more than 99.7% of the population.

In accordance with the trends in developing countries and with the foreseeable and expected development of the national economy, the ERMES radio-contact service is aiming for the consumer market. Here, like GSM in the mobile telephone sector, it could play the role of a universal paging system. The Czech radio-contact market will then become compatible with the European market and will be able to provide its clients and customers with all services routine in Western European countries. This means quality RDS paging for the professional market and the high-capacity universal ERMES system for all-purpose use. Let#s hope it#ll be soon.

© 1996 United Communication