Airwave, the operator for Great Britain’s TETRA emergency service network, and Axell Wireless have teamed up to produce an enhanced TETRA repeater, which provides extra capacity, wider coverage and lower costs, especially during Network rollout or technology refresh. The new product was announced at TETRA World Congress 2012 in Dubai last week (16 May).
Axell has supplied the core technology for the enhanced repeater, while Airwave has brought its design and network operational experience to the product.
Axell Wireless CEO Ian Brown told Wireless the thinking behind the product. ‘We are looking at how we can help lower the operating costs of PMR networks. One way to do that is to have fewer base stations. But to do that you need to find a way to extend the coverage of your existing technology.’
A network generally has central base stations with a number of other base stations clustered around it. But to avoid interfering with each other they have to transmit on different frequencies. If they are on the same frequency inter symbol interference (ISI) is created, which causes problems for radio users.
What Airwave and Axell have done is to find a way to allow the base stations to transmit on the same frequency, but avoid ISI.
‘You beef up the central base station to provide a higher throughput and more horsepower,’ said Brown. ‘But if you have other base stations around the central one they have to be on a different frequency to avoid interference. So, if you get rid of those base stations and replace them with repeaters, they can all operate on one frequency and that frees up spectrum.’
The central base station and the enhanced repeaters can transmit on the same frequency by imposing micro-second delays to the signals at the base station to ensure the signals reach the radios at the same time through variable delay. By providing these signal ‘hops’ the coverage is extended via the enhanced repeaters and so fewer base stations are required.
Network operators will be able to significantly reduce their operating costs as a result. Brown said: ‘The cost of running base stations is very expensive in terms of power consumption – around 650W is dissipated. With the enhanced repeaters 180W is dissipated.
‘In addition, it is sometimes tricky to get power to isolated base stations. You cannot use solar or wind technology to generate enough power to run a base station, but you can use them to run an enhanced repeater, so there are more cost savings to be had there. And if you have fewer base stations in your network, your maintenance costs go down too,’ said Brown.
Airwave CEO Richard Bobbett told Wireless: ‘The new product provides a great opportunity to extend network coverage at a lower price point than we have ever seen before. It takes fairly basic technology that has been around for a while and uses it to solve the problem of intersymbol interference. You can get more cover for the same price or the same coverage at a lower cost. You can also use it to extend in-building coverage.’
Bobbett continued: ‘For new build networks it is a no brainer, but in the long term it will also reduce the cost of operating existing networks. But for those you first have to resolve the cost of change issue, which is the challenge for existing networks.’
The enhanced repeater is vendor agnostic so it can be used with any network suppliers’ equipment and it is ready to go to market now. Airwave and Axell will be taking the product to market in partnership with one or other company in the lead depending on how well they are established in particular countries.