Axell Wireless has provided equipment to upgrade Singapore’s public safety network to support TETRA. The project covers every major iconic and government building in the country, as well as the entire metro network.
The decision was made to upgrade the system to support the needs of Singapore’s emergency services and Axell was selected to supply the equipment due to the company’s expertise in similar high-profile TETRA deployments around the world, and its market leading digital technology. The new system provides the country with a flexible, future-proof network with scope for further enhancements should they be required.
To meet the challenging specifications, Axell supplied a network of digital channel selective off-air systems for in-building coverage and selected outdoor areas of Singapore. Axell’s fibre DAS (Distributed Antenna System) solutions were chosen to provide coverage inside the metro, which currently consists of 180km of lines and plans are in place for it to double in size by 2030.
The limited amount of existing fibre at a number of Singapore Metro stations presented additional challenges to the deployment. Axell’s engineering experts enabled a fibre optimisation strategy, providing public safety coverage at all metro stations without the need for the additional costs associated with further fibre deployment.
The entire public safety network is monitored using Axell’s remote monitoring system, AEM (Axell Element Manager). The system allows the support teams to manage equipment from multiple sites, closely monitoring the network and identifying the need for changes as and when they arise, keeping them in full control at all times.
Speaking to Wireless at Critical Communications World 2014 in Singapore (20-22 May), Sameer Kaul, VP Sales for APAC at Axell Wireless, said: “We did a similar network in Hong Kong where we supplied nationwide TETRA coverage, although we used a 7MHz bandwidth there, whereas TETRA is normally in a 5MHz bandwidth.
“For the Singapore system we used fibre optic systems predominately for the underground metro and off-air systems for small to medium government buildings. TETRA doesn’t need much capacity, it’s more about ensuring coverage. We have installed hundreds of remotes in the tunnels and are using leaky feeders for the connectivity,” says Kaul.
Singapore is building a new metro line, known as the Downtown Line. Kaul says that Phase 1, which includes 44 stations, is complete. “We’ve already received orders for cellular coverage too and a couple of days ago we received an order for LTE as well, so there will be TETRA, which is a separate network to ensure resiliency, and 2G/3G cellular and 4G LTE. They had already ordered the 2G and 3G coverage, so we now need to add an LTE box to remote sites.”
However, he notes: “It is lucky that only Phase 1 is completed as Phase 2 and 3 are the major phases with tunnels. We can install single quad-band boxes, so that has the advantage of a smaller footprint. Space is the big constraint in tunnels, so if we’d used a standard off-the-shelf box it probably wouldn’t have worked, as there isn’t enough space.
“We had to create a thinner, longer box instead, as depth is the issue. We redesigned the box with heat synchs at the sides and back and redesigned the power supply units (PSUs),” explains Kaul.
When it comes to installing coverage in tunnels, Kaul says ensuring reliability is the number one pre-requisite. “You don’t want to have to halt the trains to do repairs.” The second major pre-requisite is having the ability to customise your solution – increasing the power requirement, for example.
Singapore Sports Hub
Elsewhere is Singapore, Axell is involved in supplying coverage to the massive S$1.3bn Singapore Sports Hub project (pictured below), as 35ha complex currently under construction in Kallang, which includes a 55,000 capacity stadium, aquatics centre, 3,000-seater sports arena and other facilities.
“Local firm Consistel is our system integrator partners for this,” says Kaul. “The same TETRA systems used by the emergency services elsewhere will be used there too. It’s a similar system and DAS solution, so that makes provision of spare parts and so on much easier. Comsistel will run build, maintain and operate the system under a neutral hosting model.
“The client chose our DAS system, because they wanted a leading vendor with a reputation for reliable equipment. Our equipment is the standard as far as public communications are concerned. Customers know it works and they don’t want to take a risk.”
Kaul reports that Axell has seen good success in Australia for TETRA recently. Australia has strict regulations over the way users can transmit and receive wireless signals overground using repeaters. Signals have to be limited to very narrow channels (very difficult to do with analogue signals, but easier with digital) and must not cause any interference with other private wireless LANs.
Axell has made a breakthrough by becoming the only company so far to be approved by the Australian Communications and Media Authority (ACMA) to transmit signals using repeaters overground.
Kaul says: “Before you would have had to use base stations, which are much more expensive than repeaters, of course. Now customers can use repeaters with our equipment that lowers their power consumption, heating costs and so on, which reduces the total operating costs for both capex and opex.
“Customers, such as mining companies in Australia, had not thought of using TETRA systems before, but now they can expand their communication systems. So far, it has been deployed for both underground and above ground mining, but we are also looking at rail links too. We can use frequencing shifting equipment to go long distance on railways, so that can extend the signal quite a bit,’ says Kaul.
Axell has been using frequencing shifting for cellular operators to provide coverage along railway lines for some time. It does not help increase capacity, but it does extend coverage.
It has also used the technique in places like the Maldives where a lot of the islands are either uninhabited or only sparsely so, but coverage is still needed. But putting in a base station would be prohibitively expensive, so the problem is solved by extending the signal using repeaters.