Negotiating antenna locations - wireless networks Print this article
The proliferation of antenna structures is a modern phenomenon and, at one time or another, most people on viewing them on a hilltop or a hotel roof must have asked themselves, why there? Diarmuid Moran provides a detailed insight into a little-known process which has such a great influence on our day-to-day surroundings, as well as playing a vital role in our modern communications infrastructure
The locations of telecom base stations and associated antennas are dictated by supply and demand, combined with various other factors. Engineers design them, engineers plan their coverage potential, site providers make locations available, town planners and acquisition experts deal with the finer aspects of location and design.
The base stations generally need to combine into a large network for economic and mobile coverage reasons. Most wireless rollout projects entail the development of hundreds of base station sites requiring regional or nationwide coordination and programme management of the various disciplines to ensure project success.
Antennas are generally owned by service providers/wireless network operators who have procured a COMREG licence to utilise radio spectrum (www.comreg.ie) using their chosen technology. Such technologies include GSM, UMTS (3G), Tetra, WiMax and related IEEE/ISO/IEC proprietary wireless protocols (www.ieee.org ) and various UHF, VHF, microwave and broadcast technologies up to the latest Digital Terrestrial TV (DTTV standards www.cenelec.eu and www.etsi.org ). Given the licence or the investment approvals to build or upgrade technology on a network, the ‘roll-out’ commences based on the following planning and negotiation activity.
Radio and transmission/network planning
This activity is a technical and topographical discipline that matches the desired user coverage level (measured in dB for the handset, in-car or building), and capacity to proposed base stations locations and, in turn, linkages to the large networks. There is great variability associated with topography, which makes some sites better than others. The best sites are overlooking the desired user population with suitable infrastructure, for example, Three Rock Mountain in Dublin or Churchfield in Cork City.
Distance or height can increase potential user numbers, but decrease signal levels and performance, so this has to be considered based on the technology, power and frequency characteristics.
Radio engineers use their knowledge, skills and various software packages to match the topography and variables. The variables can include user types and numbers, frequency, technology, landscape factors such as obstacles (clutter), weather, contingency, capacity and criticality. When the budget is considered, the key costs are based on the number of base stations required (density), considering that some ideal sites may not be available for budgetary, planning, competition or other reasons.
The second engineering discipline associated with the planning of networks relates to capacity and network connectivity. This is called the transmission network and it is what brings the radio base stations together into a core network, or onto a backbone-trunked system, such as a metropolitan area network (MAN). The transmission network is based on an aggregation of the end-users who are channelled to various switching, data management and value added gateways.
Fibre is the preferable high-capacity channel from the base stations to the core network; however, microwave radio links, copper and sometimes trunking of base stations together is necessary.
An element of service quality comes into play in the networking and overlapping of the base stations. The desired solution is base stations matched to users and transmission capacity, with 100 per cent uptime/contingency at the cheapest cost with expandability and ease of access. Unfortunately this perfect optimisation is rarely achieved.
The challenge is based on knowledge of site capacity, inter-site distances, signal ‘hand-over/pairing’ and connectivity options.
Generally the transmission hierarchy will favour fibre, copper land-lines, high capacity microwave, laser or lower capacity microwave point to point links in that order. A well-planned network topology will save an operator significant trouble and expense.
Obviously, existing communications infrastructure is considered, and planning must also take account of existing nodes and services such as, telephone exchanges, accessible MANs or other available ‘core’ networks. Certain clients will require the use of existing sites they control or use, which can add to complexity but reduce costs.
Site acquisition
The acquisition discipline has the objective of getting sites in the designated area that provide the required coverage at the appropriate price. As mentioned there are a variety of sites available: ‘the good, the bad and the ugly’. Add to this the ‘expensive and the sensitive’. A new network can lease or buy new sites and an existing network may just need to upgrade or add to site equipment.
A key acquisition skill, certainly for new sites, is negotiation. In this respect the major financial aspects are site rental and construction costs, bearing in mind the transmission and planning factors. Planning permissions and frequent appeals to An Bord Pleanála can obviously delay network roll-outs.
There is a system of planning exemptions that can be applied under the 2001 Planning and Development Regulations (S.I. No. 600 of 2001) subject to location, notification and design requirements applicable on certain site types.
Generally sites are grouped in the following manner:
- Greenfield (usually a new pole, mast or tower);
- Rooftop; and,
- Co-location on an existing structure.
There are a number of nationwide site providers in Ireland that include TowerCom, ESB, RTÉ, CIÉ and the OPW. The main operators also share their owned or leased sites often on a reciprocal basis.
Electrical management
The base stations present an interesting range of options for the provision of electricity. Urban rooftops and co-locations can utilise new ESB connections, or the preferred but relatively expensive multi-metering solutions. Greenfield and hilltop locations often require new or upgraded ESB connections with associated project management issues such as routing, timing, ducting and costs.
Lightning protection is also an evolving and sometimes a contended requirement. Green energy is a viable option, as battery stand-by power is an existing feature and power generators are also available on many base stations. A number of ~ 5kW wind turbines have been successfully deployed at base station sites. There are undoubtedly a number of economic and smart solutions to energy and resource sharing particularly on the remoter exposed sites. The broader site design, programme roll-out and construction management activities present a range of challenges not addressed in this article.
New developments
The National Digital Radio Service is an example of a new ultra-secure, shared network for the Gardaí, ambulance, fire, customs and other agencies. This very successful system was recently switched-on by Tetra Ireland. Much of the site acquisition, design, customised engineering solutions and build project-management processes were provided by Threefold Project Management Ltd.
Other developments with 3G and WiMax technology, fibre-optic integration, GPS timing, energy, economics and safety management continue to create changes and challenges. Further sharing of both user-access and core backbone infrastructure is emerging with the likes of the recently ratified (November 24, 2009) EU Telecommunications Directive set to force more efficient technical solutions and greater market competition. Much of the evolution and innovation in wireless infrastructure has been progressed by engineers and visionaries.
There has been an evolving partnership model at the OEM and network roll-out level with clients seeking turnkey networks from equipment manufacturers/suppliers. The developments have been expansionary with newer technology, markets and wireless-user expectations since the pioneering ‘088’ analogue service of the 80s and 90s.
Dr Diarmuid Moran is the risk, safety and fleet manager with Threefold Project Management Ltd and also the owner of Bowline Risk Management Ltd. Diarmuid is a MIEI and holds a BSc from DIT and a PhD from Trinity College. His experience includes employment with Seagate Technology (NI) and Wyeth Medica, as well as more recently five years with Eircell/Vodafone Ireland and six years with Threefold,which specialises in the coordination and management of the various engineering and professional services required to develop wireless networks.
Threefold is an Irish company that undertakes these projects for clients such as Meteor, O2, Eircom, 3 Ireland and other broadband providers. Threefold coordinates and manages the following various disciplines: radio/transmission planning, site acquisition negotiations, town and country planning, site design, construction works including civil, electrical, rigging, equipment installation/commissioning.