TETRA FactsheetVersion 2.2: 1 November 2005 Digital trunked radio systems are modern radio systems for private and public professional radio applications and for emergency radio applications (PMR/PAMR1). TETRA will allow more economical solutions than to date due to its uniform technical basis and large unit quantities. energy companies and the emergency services (e. In addition. including ASTRO and iDEN (both by Motorola). The number of potential users in Europe is estimated to be 10 million2.6 billion euros per year. initial attempts were being made to seek appropriate solutions for digital PMR systems.3% per year is being forecast from various sides. the frontier police. Of this. However. Trunked radio systems differ from public mobile radio systems such as GSM or UMTS primarily in terms of their faster call set-up. All these user groups either have their own private trunked radio system or use the services of a trunked radio systems operator. etc. A growth rate of 2% . etc. the quality and security of radio systems could be considerably improved using digital technology. 80 ff. Since then. in addition to offering a high degree of flexibility. . Swiss Federal Railways. Unlike earlier conventional analogue fixed-channel systems (a specific radio channel was allocated to each service and each user for the whole time). Potential users of trunked radio systems include closed user groups such as transport services (taxis. designated TETRA. haulage companies. in the case of trunked radio systems frequencies are allocated dynamically to individual users and services. It is therefore possible to fully utilise so-called trunk gain and to increase spectrum efficiency. 2 1 Funkschau 5/98. airports. PAMR operators also generally offer access to the fixed network. probably relates to Europe − with approx.g. comparable only to the successful GSM standard for mobile radio systems. priority calls. about one third. with PAMR the trunked radio services are obtained from an independent network operator. or almost CHF 7 billion. end-to-end encryption and the possibility of direct calls from mobile station to mobile station without a connection via a base station (this is known as direct mode). SR 440 (Bosch/Ascom) and Tetrapol (Matra Communication). cellular trunked radio system for voice and data communication. ambulance services. police. TETRA has become one of the most comprehensive standards ever developed by ETSI. approximately 90% of professional radio systems are still based on analogue technology.5 billion euros. 2 Development in Europe The market for professional mobile radio systems world-wide is approximately 4. or 1.). the establishment of a uniform standard for digital PMR systems began only when manufacturers. 6 million users. civil defence. penetration is already up to The market for professional mobile radio is designated PMR (Private Mobile Radio) or PAMR (Public Access Mobile Radio). Today. In the case of PMR the radio system is operated by the user himself. This step was essential in order to increase spectrum efficiency. p. there. administrations and user groups decided within ETSI in 1989 to draw up such a standard. the army. group calls. It was at this time that the first proprietary digital PMR systems appeared. improve technical reliability and facilitate encryption of the connection.).TETRA Factsheet 2/14 1 Introduction TETRA is a digital. EDACS (Ericsson). This growth is expected because market penetration of PMR systems in Europe amounts to only 2%. It is expected that in spite of its considerable complexity. As early as the first half of the 'eighties. Compared with the USA this is low. the fire brigade. 430 MHz band. Booth Drive. approximately 90% of the PMR systems in Europe today are still based on outmoded analogue technology. The licensing of regional networks is now being examined. 5 6 TETRA Swiss News. Wellingborough. At the same time interest was shown in regional networks. In the lower frequency range the available channels were not sufficient to set up a viable trunked radio network. The market trend in PMR and in emergency radio applications in particular clearly points in the direction of large. A total of 1. Of these. NN8 6GR. Email: sales@imsresearch. Part 1. ComCom reacted to this trend as early as 1999 by commissioning OFCOM to undertake a clarification of demand in the 870 876 MHz / 915 . Issue 5. In spring 2000 OFCOM was again asked to undertake a study of demand (in the 410 . the possible introduction of digital trunked radio applications for special communications purposes has emerged. however. Estimates indicate that by 2003 approximately 80% of the digital PMR market in Europe will be operating using TETRA technology. Intex Management Services Ltd. it is much more important to know what services can be provided by TETRA. 1 August 2000. however. since the essential continuous frequency ranges were not available. "Methodology for Assessment of PMR Systems in terms of Spectrum Efficiency. Explanatory report.430 MHz frequency range). In addition. Fax: +44 (0)1933 40 22 66. The introduction of a digital trunked radio network was excluded. When the deadline for submissions expired on 22.921 MHz band and to organise an invitation to tender in the 410 . Operation and Implementation". 3 4 Tetrapol PAS Conversion by ETSI.4 Today (in 2001). See also: ERC Report 52. despite the restitution of the Modacom company's frequencies. in addition to the increasing penetration of GSM. The results of this work showed that there was no great interest in the upper frequency range. England.22 million participants are forecast in 2003 in the digital PMR market in Europe. around 80% will be using TETRA technology6. this frequency band was still heavily occupied by the Swisscom analogue trunked radio network (Speedcom) and by individual professional radio applications. jointly used networks. no candidature dossiers for a national licence had been received. more than 40 regional or national organisations and services in Europe are equipped with TETRA systems5. 6 Dencora Business Park.TETRA Factsheet 3/14 8%3. The results of the study showed that the number of interested parties had grown fundamentally and that today a viable network could be set up with the additional frequencies.2000.com .12. 3 Licences in Switzerland In the international environment within the mobile radio applications sector. Tel: +44 (0)1933 40 22 55. ComCom commissioned OFCOM to organise an invitation to tender with regard to auctioning a national licence. gas and water supply) as well as the transport industry are outsourcing their radio activities more and more to specialist trunked radio operators. it is mainly the characteristics of the radio channel and the structure of TETRA channels at the physical level of the air interface which have been considered. At that time. This decision led ComCom to reassess the situation. In the year 2000 Swisscom officially announced that it would be withdrawing from the Speedcom business as of 30 September 2000. 4 Services Thus far. Traditional users of PMR systems such as public utility companies (electricity. which will be replaced sooner or later by more modern digital systems. For the user. The list below is not exhaustive and contains merely a small selection of services which can be provided by TETRA.TETRA Factsheet 4/14 In simple terms it can be said that TETRA can provide almost everything which has been possible to date with conventional PMR systems. Short Data Service: predefined messages can be sent to individual subscribers or to a group.8 kbit/s n x 2. The group call can be set up so that the individual members have to acknowledge or not. 2. however. Teleservices: Individual Call: This service corresponds to a call in a public mobile radio system (GSM. two or more mobile stations communicate with each other. plus a wide range of possibilities on the ever more important data communications side. Pre-emptive Priority Call and Call Retention) (see ETR 120). without involving a base station (walkie-talkie). Within the group. 3 or 4) . Many of these services are not yet available in the public mobile radio systems. A group can be modified dynamically. this type of call makes it possible to ring one or more additional users and include them in the call. i. Carrier services (data services): Status Transmission: very short.g. Group Call: One user calls a predefined group. members can be added or removed. 2. Open Channel: A group of users can converse with each other on a specific channel for a specific period. UMTS). all participants can hear each other and can speak at any time. Include Call: During a call.2 kbit/s n x 4. In TETRA this service is not explicitly standardised. 2. Direct Mode: In direct mode.e.4 kbit/s (n = 1. 3 or 4) (n = 1. it can be installed with the aid of a broad range of extra services (e. To illustrate this. However. Emergency Call: An emergency call button sets up a high-priority call to a dispatcher or a predefined group of users. predefined messages can be transferred from the dispatcher to the mobile stations and vice versa or between mobile stations. including IP telephony. Estimates indicate that by 2004 more than 50% of all radio communications will consists of packet data traffic. Each member of the group can hear everything and can speak. Broadcast Call: This is a unidirectional point-to-multipoint call within a specified area. The individual users do not acknowledge the call and therefore the caller is unable to verify who has and who has not received the call. One user calls another individual user and is connected with the latter. 3 or 4) (n = 1. we have sub-divided the services into different groups: teleservices. Circuit-switched data services: non-protected data transmission: protected data transmission: highly protected data transmission: n x 7. The area and the users are defined in advance. carrier services (or data services) and supplementary services. TETRA's flexible system and interface structure offers even more opportunities. In addition. TETRA Factsheet 5/14 (n = number of time slots which are used on a carrier frequency). 5 5. No virtual circuit is established. For an individual mobile radio transmitter installation. Packet-switched data services: call-oriented packet data services: transmission of X.25 packets from a source node to a destination node. This service is important above all for the police or other security services. Ambience Listening: This supplementary service allows the dispatcher to listen in unnoticed to a vehicle in unclear and dangerous situations. The call is then processed before all other calls which have a lower priority. Supplementary services: Discreet Listening: an authorised person can monitor radio communications without the subscribers concerned being aware of this. Such . the necessary resources can be released by means of the so-called Pre-emptive Priority Call. On the one hand the decree contains requirements for individual items of equipment. Late Entry: This supplementary service allows a user to connect at a later time to a group call. Priority Call: This supplementary service allows a user to allocate a priority to the call. WAP is also now offered in TETRA networks. on the other hand. for example if he was engaged at the time of the call or if he had not yet switched his equipment on.g. the same requirements as in the EU are applicable for Switzerland: The recommendations of ICNIRP (International Commission on Non-Ionizing Radiation Protection) have to be implemented in the context of the applicable technical norms. If no more network resources are available (e. TCP/IP Access: this data service allows the mobile stations to access the Internet or servers which support the TCP/IP protocol.1 Environmental provisions Protection from non-ionising radiation Both the base station transmitter antennas and the TETRA mobile sets will emit additional non-ionising radiation into the environment. The radiation from the base stations. non-call packet data services: a single data packet is transferred from a source node to a destination mode (or multiple destination nodes). indirectly. all channels are busy). The calls with the lowest priority are consequently aborted in this case. the use of the frequency spectrum as a whole. is limited by the Decree on NonIonising Radiation (Verordnung über den Schutz vor nichtionisierender Strahlung . A logical or virtual circuit is established between the two nodes. and on the other hand it limits total high-frequency radiation and therefore. the decree states that its radiation in locations subject to sensitive use may not exceed the limit value for the equipment. With regard to the intensity of the radiation from mobile stations.NISV). ch/buwal/de/fachgebiete/fg_nis/index. In the case of mobile radio equipment. The size of this separation depends very greatly on the transmitter power and direction of radiation of the equipment.10. In order to balance the interests of the construction of telecommunications networks and the associated offering of telecommunication services against the interests of environmental protection and area planning in practice.bakom. Details for the implementation of the NISV can be taken from the recommendations of BUWAL under: www. . For the total high-frequency radiation. has been considering questions of coordinating the planning and approval procedures for radio infrastructures. obligations are stipulated according to which antenna sites outside construction zones are to be used jointly. To this end. The recommendations have been published on OFCOM's homepage (www. Compliance with the equipment limit value is checked by the competent planning authority of the community or canton. The equipment includes all contiguous transmitter antennas for mobile radio and wireless subscriber connections. the licensee provides proof that the immission limits will not be exceeded by the radiation additionally generated by the planned installation.TETRA Factsheet 6/14 locations include rooms in buildings in which people regularly spend prolonged periods of time. the Federal Office for the Environment. a certain separation is essential between the transmitter equipment and locations subject to sensitive use. children's playgrounds as designated by planning law. protection of nature and the national heritage and the provisions of the decree on protection from non-ionising radiation must be complied with. such potentially critical situations occur almost exclusively on accessible flat roofs on which a transmitter installation is mounted. lay or modify. and on topographical conditions. professional radio and amateur radio equipment. as part of the granting of the operators' licences. and then mostly in the immediate vicinity of a transmitter installation. Landscape Department) published a notice concerning the requirements for the protection of nature and the landscape and for forest conservation with regard to the construction of mobile radio antennas. In addition.umwelt-schweiz. and non-built-up construction areas. including that of broadcasting.ch). which works in the frequency range between 400 and 500 MHz. In order that the equipment limit value can be complied with. In the site data sheet. On 30. for each transmission installation which the licensee wishes to construct. The equipment limit value is laid down for the electrical field intensity and is generally 3 V/m for TETRA equipment.2 Consideration of environmental concerns The construction of new telecommunications networks necessarily leads to the erection of new infrastructures such as antenna installations. if possible. In the case of construction of new sites.1998. This site data sheet is a component of the planning application and may be made accessible to the public by the planning authority. Forests and the Landscape (BUWAL. a working group of the Confederation and the cantons (UVEK/BPUK). The relevant limits – termed the immission limits – are seldom achieved or exceeded.html 5. with the co-operation of radio network operators. the licensee completes a site data sheet which must contain technical information on the equipment and a prognosis of the radiation intensity in adjacent areas where people may be present. the legal provisions concerning area planning. the decree imposes a limit at all locations where people may be present – even for a short time. 167 ms) Transmitter sampling for channel 1 Channel 1 Channel 2 Channel 3 Channel 4 Channel 1 Figure 1: TETRA's TDMA channel access procedure As for GSM. the radio channel can be used by other users. This control channel is used to transfer the network's system data to the handsets and to allow synchronisation between handsets and the base station. however. The transmitting power of the mobile equipment is continuously regulated by commands from the base station to the respective minimum which the base station needs to detect the data from the mobile equipment (power control). 1 TDMA frame (56. is not regulated in TETRA. During the remaining period. Though this linear modulation method is extremely spectrum-efficient. The modulation method used is π/4-DQPSK (Differential Quaternary Phase Shift Keying). however. Direct Mode. it requires very linear and therefore expensive transmitter final stages in order to generate low out-of-band transmissions which are undesirable. If necessary for high transmission capacity. on the other hand. One individual channel is occupied only for one quarter of the time for the duration of a time slot. The principle of the procedure is shown in figure 1. the transmitter is therefore switched on and off approximately 18 times per second. In principle. The transmitting power of the base station. TETRA can be used on all frequencies below 1 GHz. In practice. This relatively high data rate makes TETRA especially suitable for use in mobile data transmission. Packet Data Optimised (PDO). TETRA's maximum data rate is up to 28. Both voice and data can be transmitted simultaneously by a single user. only the typical frequencies authorised for PMR in the 160. TETRA provides four independent communication channels within one 25 kHz radio channel.TETRA Factsheet 7/14 6 Technology The channel access procedure used for TETRA is the TDMA (Time Division Multiple Access) method. in the TETRA system the control channel is also transmitted on a specific carrier in the first slot in each frame. The TETRA specifications cover three quite different areas of application. one individual user can also occupy multiple time slots (up to four).8 kbit/s (non-protected) for a 25 kHz channel bandwidth. 400 and 870 MHz band are used (see chapter 0). By means of this power control.67 ms) 1 time slot (14. namely: Voice plus Data (V+D). . On a call. on the one hand interference can be minimised and on the other hand the battery life of the mobile equipment can be maximised. . Direct mode allows a direct link from mobile station to mobile station without involving a base station. the air interface of PDO is more suitable for the transmission of packet-based data.g. This mode is used when users are outside the coverage area. TETRA also uses the frequency duplex method (apart from Direct Mode.e. these are based on the same physical radio platform (modulation. As with most radio systems. frequencies. which are separated from each other by so-called duplex separation. up to two independent simplex calls can be maintained simultaneously on one carrier.public mobile systems and fixed telephony . Equipment complying with the V+D specification offers a wide range of carrier services. A brief comparison of these two systems is therefore appropriate and is shown in Table 1 (a separate factsheet is available for Tetrapol). however this mode is not used very frequently in TETRA systems. TETRA terminals (like those of most PMR systems) generally work in half-duplex mode. The size of this duplex separation depends on the frequency band in which the system is operated.TETRA Factsheet 8/14 Different standards have been developed for these three applications. i.). etc. Full-duplex operation corresponds to the mode with which we are familiar . only simplex operation is possible.and would be easy to implement in TETRA. Although packet-based data services can also be transmitted from V+D equipment. This is of particular interest in that in the near future data services − especially packet-switched data services (e. RF channel spacing. see below). The uplink and downlink are handled on two different frequencies. In the case of direct mode. Internet access) − will become more and more significant. Equipment complying with the PDO specification supports only packet-switched data services. The mobile stations involved in a call work on the same frequency. However. Tetrapol and TETRA are the most well-known digital trunked radio systems in Europe. teleservices and supplementary services for hybrid voice and data transmission. it is not possible to send and receive simultaneously. In the case of direct mode. TETRA therefore needs about Voice and data can be transferred simultaneously with twice as many base stations as Tetrapol to cover a specific TETRA. whole frequency blocks must be allocated. TETRA's spectrum efficiency is greater than that of With TETRA. 30% smaller than those of Tetrapol (assuming the same peak transmission powers). since TDMA (time-division multiple access) means that 4 channels are available for each carrier frequency. A less expensive antenna network is required in the base station. Devices with TDMA channel access tend to have greater whereas Tetrapol has not yet been accepted as an ETSI peak transmission powers and may induce audible lowstandard. area. powerful equaliser (MS Class E).TETRA Factsheet 9/14 Table 1: Advantages and disadvantages of TETRA compared with Tetrapol Advantages of TETRA compared with Tetrapol Disadvantages of TETRA compared with Tetrapol TETRA's data rates are clearly higher than those of The maximum cell radii of TETRA are approximately Tetrapol (up to a factor of 4 depending on trunking). With TETRA the transmitting output of the mobile station is regulated by the base station and adapted to current conditions. Table 2 below summarises the most important radio parameters of TETRA. Duplex mode is possible with TETRA without an With TETRA. Frequency allocation is more difficult. common-frequency transmissions are Tetrapol (by a factor of 1. out-of-band emissions are greater than antenna splitter thanks to the TDMA channel access with Tetrapol. possible.16 to 2. . the battery life of the mobile station is increased and interference in the network is reduced.0 depending on the more difficult to implement and require terminals with a environment). TETRA is an extremely flexible system and can be used for all PMR applications as well as for emergency radio and conventional PMR/PAMR. TETRA is an acknowledged European standard. As a result. frequency interference in electro-acoustic equipment. If method and is therefore simple to implement. 921 MHz). 870 .470 MHz). propagation model SE21. antenna height MS = 1. 10 W MS: -113 dBm BTS: -115 dBm MS: -104 dBm BTS: -106 dBm Semi-duplex.430 MHz. N = 4) Receiver sensitivity.2 kbit/s Low-protected: n x 4. antenna gains and feed losses = 0 dB. reliability of coverage at edge of cell = 90%.5 km ETS 300 392 ETS 300 393 ETS 300 396 ETS 300 394 Speech coding Spectrum efficiency in interference-limited environment (high traffic. 7 Frequencies Basically.8 kbit/s High-protected: n x 2.876 MHz paired with 915 . σS (shadowing) = 6 dB.2%. The 385 .390 MHz paired with 395 – 399. BER = 1.470 MHz. 4. 4. 14 km ca. duplex TDMA π/4-DQPSK 36 kbit/s 28.567 kbit/s 50 bit/(s*kHz*cell) 384 bit/(s*kHz) Rural: Suburban: ca. 3 or 4) A-CELP. In Switzerland it is envisaged to make available a total of 1.8 kbit/s Non-protected: n x 7. 4. f = 400 MHz. 385 . antenna height BTS = 30 m. interference margin = 1 dB. static (BER = 1.876 MHz paired with 915 . In Switzerland.5 MHz of spectrum (in three subranges) from the 410 – 430 MHz range for several fairly large regional or one national digital .5 m. since all other ranges are either heavily occupied by other applications (450 . non-protected (gross bit rate) Net data rate a) Value 25 kHz 25 W ERP 1 W. Dynamic. 3 W. PMS = 3 W (peak power).9 MHz cannot be used for civilian applications in Switzerland.9 MHz. or no equipment is currently available (870 . 450 .430 MHz range can be considered for the introduction of larger regional or national TETRA systems. 4.8 kbit/s. at present only the 410 .TETRA Factsheet 10/14 Table 2: Major radio parameters of TETRA Parameter Channel spacing Transmission power of base station per carrier frequency (typical) Transmission power of mobile equipment Receiver sensitivity. the following frequency ranges are available in Europe for digital trunked radio (ERC/DEC(96)04): 410 . 2.8 kbit/s. many cells) Spectrum efficiency in noise-limited environment (an isolated cell) Range b) ETSI standard TETRA V+D: TETRA PDO: TETRA DMO: Testing: Notes: a) b) Class A equipment (optimised for hilly or mountainous terrain). dynamic (TU50.2%.921 MHz. N = 4) Mode Channel access method Modulation Channel bit rate Maximum data rate.4 kbit/s (n = 1.390 MHz frequency range paired with 395 – 399. e. There is also a possibility of making available a limited number of frequencies in the 450 . simulcast). In this case. The air interface. are typically installed in one cell. Both the high-frequency signal and the temporal position of the . No special type of network implementation for building a network is laid down in the standard. If traffic is low and coverage is ample.TETRA Factsheet 11/14 trunked radio network (see chapter 3). The spectrum efficiency is heavily dependent on these parameters (see Table 2). interworking and network management can be guaranteed between the individual network elements. TETRA can also make use of common-channel technology (co-channel radio. at airports). The TETRA standard may be considered as a "tool kit" and offers system designers many opportunities to adapt the network optimally to users' needs. Consequently traffic is low and in general large cells can be built. if necessary. volume of traffic and services provided.470 MHz range for local TETRA networks (e. 8 Networks Digital trunked radio systems for PMR − compared with public mobile radio systems such as GSM or UMTS − generally have small numbers of users with short call durations.e. The different PMR systems differ very greatly in terms of the number of users. The radiated transmission power per base station carrier frequency is of the order of 25 W ERP. the interface between the infrastructure (SwMI) and the mobile equipment. all base stations transmit on exactly the same frequency.g. i. for example. I6 (DMO) I1 SwMI Transit network MS MS BTS Gateways LSC MSC TETRA 1 I3 (connects two TETRA networks) I3 TETRA 2 PSTN ISDN I2 LS BTS DMO ISDN LSC LS MS MSC PSTN SwMI Base Transceiver Station Direct Mode Operation Integrated Services Digital Network Local Switching Centre Line Station Mobilstation Main Switching Centre Public Switched Telecommunication Network Switching and Management Infrastructure Major Interfaces: I1 Air Interface I2 Line Station Interface I3 Inter-system Interface (ISI) I6 Direct Mode Radio Air Interface Figure 2: Network configuration with the most important TETRA interfaces Connection of a TETRA network to other telecommunications networks such as PSTN or ISDN is guaranteed via standardised gateways. The specifications merely define the interfaces which are essential so that interoperability. In TETRA. Some systems are noise-limited (system limits are determined by the receiver noise) or interference-limited (high common-channel interference from adjacent channels is present). the coverage area. i. is one of these interfaces (see Figure 2). 16 to 20 logical channels. 4 to 5 carriers. With this procedure. the terminals must be equipped with a special filter (an equaliser) so that they can be used for co-channel technology. which is fed by multiple base stations. . The network can be considered as a single giant macrocell. it is possible to achieve excellent coverage of a large but low-traffic location.TETRA Factsheet 12/14 modulation signal are sent synchronously from the base stations. Because of TETRA's high bit rate. with simultaneous high frequency economy. Transport. Energy and TETRA V+D system (Voice plus Data) Wireless Application Protocol .TETRA Factsheet 13/14 Abbreviations A-CELP OFCOM BER BPUK BT BTS BUWAL DMO DQPSK ERC ERP ETR ETS ETSI FDMA GSM ISDN ITU-R MS NISV PAMR PAS PDO PMR PSTN PUEM SBB SE21 SwMI TDMA TETRA TU50 UMTS UVEK V+D WAP Algebraic . Forest and the Landscape Direct Mode Operation Differential Quaternary Phase Shift Keying European Radiocommunications Committee Effective Radiated Power ETSI Technical Report European Telecommunication Standard European Telecommunications Standards Institute Frequency Division Multiple Access Global System for Mobile communications Integrated Services Digital Network International Telecommunications Union. Radiocommunication Sector Mobile station Decree on protection from non-ionising radiation Public Access Mobile Radio Publicly Available Specifications TETRA PDO System (Packet Data Optimised) Private Mobile Radio (or Business Private Radio) Public Switched Telephone Network Probability of Undetected Erroneous Message Schweizerische Bundesbahnen (Swiss Federal Railways) ERC Working Group Spectrum Engineering. 50 kph Universal Mobile Telecommunications System Federal Department Communications for the Environment. Project Team 21 Switching and Management Infrastructure Time Division Multiple Access Trans-European Trunked Radio Typical Urban.Code Excited Linear Predictive Federal Office of Communications Bit Error Rate Swiss Conference of Directors of Planning and Environmental Protection Relative filter bandwidth Base Transceiver Station (base station) Federal Office for the Environment. TETRA Factsheet 14/14 .