PPS 10: Telecommunications
Annex C: Telecommunications Systems
C1 The following paragraphs describe the principal telecommunications systems and the physical developments associated with them. Each system has different antenna types, siting needs and other characteristics which need to be taken into account in assessing proposals.
C2 Fixed-link systems operate through cable connections (copper wire or optical fibre), and radio signals transmitted through line-of-sight antennas or satellites.
C3 The trunk networks may use fixed radio links as well as underground or above ground cables. These radio links require the provision of radio relay stations. A station usually consists of a small building to accommodate the radio equipment and a tower normally of up to 60 metres in height supporting a number of antennas. Antennas can also be located on buildings or other structures. Fixed radio link antennas are round ‘dishes’, with typical diameters of 0.3, 0.6 and 1.2 metres, although reflectors may be of other shapes and sizes.
C4 Fixed radio links operate at frequencies which require direct line of site, with range diminishing as frequency increases. The radio links must be free from obstruction, such as hills, buildings, trees or large moving objects. These factors, together with the need to take account of the curvature of the earth and differing atmospheric conditions, affect the siting and height requirements of antennas. To cover long distances, or to circumvent obstacles, intermediate repeater radio stations are often necessary. They require at least two antennas, one to receive and the other to relay the signal; other antennas may be required for additional capacity or for fall-back use.
C5 Radio links via satellites are also a form of fixed-link communication. A single antenna points towards a satellite in orbit over the earth, or, in the case of a ‘satellite earth station’, a number of antennas point at a number of satellites
C6 The antennas used for transmitting and receiving radio signals via satellite should not be confused with satellite television antennas. Whilst these use the same principles for receiving radio signals from satellites, and look similar, they provide a different function.
C7 Television broadcasters use fixed links to distribute programmes and to link to studios and some businesses also use them for private commercial networks. Another example of a fixed-link system is the local cable network, which can supply subscribers with a multi-channel service of national and local television material, films, information, inter-active data and voice telephony. The cable is installed underground and requires the erection of usually small junction boxes at intervals, while a large satellite dish is used for television reception for cable ‘head-ends’.
Fixed Radio Access (FRA)
C8 Fixed Radio Access (FRA) provides a different sort of wireless distribution., This is comes in 2 forms ofthe point to multipoint distribution of information. Instead of connecting residential and commercial properties to the public switched network by wires, like copper cable, it is possible to use radio. New networks for ‘Broadband Fixed Wireless Access’ (BFWA) services are currently being auctioneddeployed in parts of the UK with further spectrum licences to be offered later this year, and are aimed at conveying large volumes of information (e.g. high data rate services) over short distances. Narrowband FRA services are used for local telephony and other services. . Instead of connecting residential and commercial properties to the public switched network by wires, like copper cable, it is possible to use radio.. FRA operators can provide important additional competition in the local loop. They generally need to have line of sight to the served premises and hence there may be less flexibility in choice of location than for mobile services. A typical pattern would be to have a multipoint antenna on a central tall point with a circle of point radios antennas facing the central point. Such transmitters/ receivers do not need large antennnas and most are likely to be very discreet.
First Generation Mobile (Analogue)
C9 The original analogue cellular networks have now closed down, and have been replaced by GSM (see below). They are therefore not described in this Statement. However, with the closure of the analogue network, the Department would encourage operators to re-use existing sites, wherever practicable, in order to minimise the need for new second and third generation base station sites.
Second Generation Mobile (‘GSM’ Global System for Mobile)
C10 Digital Cellular GSM systems are the current generation of mobile networks, introduced in the UK in the early 1990’s. They cater for mobile telephone users, and now cover an area encompassing over 98% of the population of the UK. Whilst the operators have met their initial second generation coverage targets required by the conditions of their licence, they are still required to provide a high quality service which includes the need to meet reasonable customer demand.
C11 Coverage for each cellular system is provided by a network of radio base stations. A base station is a facility that provides transmission and reception for radio systems and each covers a certain area known as a cell.
- Macrocells provide the main structure for the base station network. The base stations for macrocells have power outputs of tens of watts and communicate with phones up to about 35 kilometres (22 miles) distant.
- Microcells are used to infill and improve the main network, especially where the volume of calls is high. They are sited in places such as airports, railway stations and shopping malls. The microcell base stations emit less power than those for macrocells and their range is a few hundred metres.
- Picocell base stations have a lower power output than those of microcells (a few watts) and are generally sited inside buildings.
C12 These systems are demand-led. Increase in the use of mobile phones has meant that operators are continually expanding their networks to accommodate customer requirements of service and quality. The greatest need for base station sites is usually in built-up areas where there is the greatest density of mobile users, and within a mile or two of the main roads, where the demands on network capacity are greatest.
C13 The size of each cell is planned by the network operators. It is determined by a number of factors, but particularly the number of subscribers expected to require access to the system during the peak usage period. In areas where usage exceeds the limits of the network, capacity can be expanded either by introducing new base stations (macrocells or microcells), or by splitting existing cells, thus effectively doubling capacity. Cell splitting requires the erection of additional antennas at an existing base station.
C14 The location of transmitter antennas is important, as signals from one cell will interfere with nearby cells on the same frequency. To avoid blind spots from buildings and hills, antennas must usually be placed high up. In urban areas antennas are often best placed on existing buildings.
C15 Cellular operators typically use vertical multiple pole type antennas about 1-3m in length, some with reflectors attached, mounted on a mast or other supporting structure. In addition, a number of small terrestrial microwave antennas (0.3m-1.2m) may be required, for example to provide links from the base station to the exchange. Associated equipment housing is usually between 4 and 35 cubic metres in volume.
C16 There are four national networks, all four operating at 1800 MHz, with two also using 900 MHz.
Third Generation Mobile (‘3G’ or ‘UMTS’ Universal Mobile Telecommunications System)
C17 3G describes a set of digital standards for future mobile telecommunications. UMTS is one of the 3G standards. These standards will enable mobile users to have access to enhanced services via higher data rates than GSM. In April 2000 the Government auctioned five new licences to third generation mobile operators. Each operator is licensed to operate a national 3G network. All 5 operators have a requirement in their licenses to build out a network covering 80% of the population by 2007.
C18 Four of the 3G operators are the UK GSM operators and it is expected that they will be able to re-use their current infrastructure in many cases to accommodate some of their new 3G network requirements. The fifth operator needs to build their 3G network from scratch. They are expected to use existing structures wherever practicable (including those owned by other operators and radio site management organisations) though they will likely also need to develop a substantial number of new sites especially in urban areas.
Terrestrial Trunk Radio System (TETRA)
C19 TETRA is an advanced digital technology standard, promoted by Europe. It is a digital standard ideal for Public Access Mobile Radio or for private network users needing multichannel operation (such as road breakdown services, use at airports or for large construction sites). Two national TETRA systems were licensed for public use in the UK, but these merged into one, which has been in operation for around two years. The UK Emergency Services new network being rolled out is a TETRA standard too and there are a few private services now in operation. TETRA base stations operate in a similar way to mobile phone base stations, in that they can be configured in cellular patterns and operate with similar powers and calling patterns. TETRA has added special features to allow local networking and override features for safety calling.
Other National and Local Networks
C20 In addition to those mentioned above there are national public networks for data and paging, national networks for maritime, aeronautical, defence, police and a number of other official services. There are also public interest national networks for rail, road breakdown, utility support, and regional networks for local health authorities, local government and many private networks (e.g. for road haulage, retail, security, taxis and couriers, agriculture and so on). These services use a variety of both analogue and digital services. Frequency bands range widely, with mobile services needing lower frequencies and fixed services needing higher bands.
C21 Radio is also used for hobby and leisure purposes. Many UK industry participants have learnt about radio through being licensed amateurs, and the Government encourages this interest. Amateurs have to pass examinations to be licensed to operate, but may then install fixed antenna subject to planning rules. Because many want to use low short-wave frequencies, these need long wire type antenna.
Satellite Television Broadcasting
C22 In the field of broadcasting, there has been significant growth in the range and use of satellite television. Satellite television is a multinational activity in view of the very high infrastructure costs. Several broadcasters transmit signals from the UK or other European countries. Television signals are beamed direct-to-home from the satellite to individual receiving antennas, the more common ones known as satellite dishes. Antennas have to be in direct line-of-sight of the geostationary satellite, and almost always have to be mounted outdoors. The satellites for the various services are in different orbital positions, and have to be received by separate antennas, unless steerable or other specialist antennas are used.
C23 The location of a satellite dish on a building will therefore depend on the direction of the satellite. The size of the dish will depend on the technology used, the strength of the signal and the possibility of interference from transmissions from other satellites that may be located nearby. New developments in antenna technology are bringing to the market new kinds of antennas with different visual characteristics.
C24 Antennas for reception of digital satellite broadcasting signals are generally much smaller and more discrete than their analogue predecessors.
C25 Digital terrestrial broadcasting uses existing TV rooftop aerials for domestic reception.
Reception of Signals
C26 Licensees providing broadcasting and other telecommunications services generally depend upon good radio signal access to their intended receivers. For example, good television reception needs to be in good range from transmitter to receiving aerial, within the intended service area of a transmitter. While the broadcasters cannot guarantee good reception for everyone, they are required by their licence conditions to provide a high quality of service; they must ensure and maintain a satisfactory signal across each area for reception on recommended equipment. The construction of new buildings or other structures, such as wind turbines, can interfere with broadcast and other telecommunications services, and the possibility of such interference can be a material planning consideration (see Policy TEL 2).