One company at the forefront of this market is Axell Wireless, which has provided systems and products to address challenges for 30 years.
The company's equipment is used to support the police network in the UK, with Airwave, and it has provided systems to the governments of Vietnam and Malaysia. It also counts numerous rail and tunnel operators, Heathrow Airport's Terminal 5 and a variety of large site operators such as power stations, coalmines and office blocks, among its customer base.
'There has been big growth in public safety networks over the last 10 years,' says Ian Brown, chief executive of Axell Wireless. 'In contrast to our competitors, we play in both the public safety and the cellular markets so we have the complete portfolio and I see customer need converging on both. For instance, a tunnel operator in Spain or Italy obviously wants to, and is legally mandated to, provide emergency services coverage within their tunnel. However, they now also want to provide additional services such as FM radio or deal with local mobile operators so the tunnel's users can take advantage of those services. Addressing both types of applications is a differentiator for us.'
Axell Wireless provides either standard, off-the-shelf systems or a customised range that is particularly useful in situations with specific requirements. Typical usage scenarios include situations in which coverage needs to be retrofitted to existing buildings that have not been designed with coverage requirements in mind. Brown gives further examples: 'Some tunnels require systems that operate using a 48 volt power supply because there is no mains electricity, while others might require their equipment to be bombproof or to operate in situations where there are temperature extremes to deal with. One customer operates our equipment in a situation where there is a 40Â°C variance in temperature during one day.'
Aside from these unique and challenging environments, there is a core public safety market that Axell Wireless addresses. 'There are the obvious first responder services and government agencies that form one part of the public safety market,' says Brown. 'As the price of wireless networks, especially TETRA, has reduced, the technology has become applicable to smaller sites and the newer private public safety market has emerged. Companies that run power plants, electricity generation facilities or coalmines, which are spread over large areas and have their own security teams, are typical private customers for these sorts of solutions. We have completed deployments at nuclear power stations in Germany, for example.'
Axell Wireless also has many clients in the rail sector that use its equipment for several applications. European railways, for example, use GSM-R to track trains and Axell Wireless provides GSM-R repeaters to ensure these critical systems operate effectively. The company is currently working with a railway operator in China to enable use of GSM-R to support traffic light signals to drivers on high-speed trains that reach a velocity of 350km/h. The issue at that speed is that traditional trackside traffic lights are not visible to the driver so the GSM-R system is used to support the driver's dashboard traffic lights.
Another element to the rail business is providing solutions that go on-board trains to provide train coverage for users. 'A good example is a Swedish rail operator that runs high-speed links between cities,' says Brown. 'Their competition is the airlines so they're trying to provide reasons for travellers to choose the train over air transport and providing high quality connections to users is a means to do that.'
Brown is also positioning Axell Wireless to address international rail journeys and is launching a product at the Mobile World Congress, which will allow the train operator's system to retune itself to local network operators when it crosses a border. The system would also enable the train operator to turn off the service if it enters a territory in which it has no agreement in place with a mobile provider.
Axell Wireless also has a strong business among the traditional cellular providers. Currently engaged with 120 providers across the world, its customer base ranges from giant players such as Vodafone and Verizon to smaller operators in countries such as the Maldives. 'For providers at the small end, there may be only 300,000 people in a large geographic area, so it's not cost effective to put base stations everywhere,' explains Brown. 'We provide operators in these locations with frequency shifting repeaters and extend their reach out to remote, rural areas.'
Repeaters are not just applicable to sparsely populated areas. 'In the fiercely competitive Indian market, we provide not only in-building solutions but also external macro coverage,' says Brown.
There are further applications for repeaters in fully matured markets. 'LTE base stations are very expensive to operate because of the cost of backhaul and operators have been looking at extending their reach by using repeaters,' Brown adds.
Axell Wireless is launching a new digital multiband repeater at Mobile World Congress that addresses GSM 900, 3G, DCS1800 and LTE in a single box. 'Operators could have subscribers for all different network types in the same building and previously would have had to deploy a number of different devices to serve them,' says Brown. 'The significant benefit of being digital is that it allows very specific filtering of channels. We expect multiband repeaters to be used for in-building applications from small office blocks, to underground transport networks and tunnels.'
Solutions for in-building coverage are very much in demand as LTE rolls out. '3G operates at higher frequencies so the higher the frequency, the harder it is to propagate into the building,' says Brown. '3G services tend to be more sensitive because they are typically supporting data that requires reliable connectivity. The in-building market has seen the most explosive growth in demand for our solutions and I think that's going to continue with LTE as well. In most European deployments, LTE will probably operate at 2.6GHz which is a very challenging frequency to manage indoors.'