‘Small-cell technology, as we go through this data tornado, is absolutely essential.’
Future mobile phone networks are set to use intelligent miniature base stations to manage vast amounts of data transfer without central planning. Phone companies and academics are researching how to cope with the huge demands on radio bandwidth that will come with the next generation of mobile technology, dubbed 4G.
Internet-enabled devices that use the new standards will receive data at up to 50 times the rate of current 3G smartphones.
Researchers at the University of York are part of a €4.7m (£3.9m) EU-funded industry project known as BuNGee (Beyond Next Generation Mobile Broadband) that is developing network infrastructure to support these new devices.
This will include a hub system for the base stations that transmit data to mobile phones. Instead of one big mast for a location, lots of miniature access stations would provide coverage for much small areas connected to a hub.
‘If you want to significantly increase the capacity density you would have to put in many more mobile masts and increase the capacity of the backwall links [to the internet],’ said Dr David Grace, head of York’s communications research group.
‘The access base station is quite cheap so you can bring high-capacity density networks into the system very cost effectively and then you put more expense on the hub base station.’
Using smaller base-stations means they can be mounted on existing structures such as buildings or street lights, avoiding the constrution of masts. Because they are transmitting shorter distances they would also use less power.
But the BuNGee devices would also use software to manage the large data transfer without the need for centralised control by making use of unlicensed radio frequencies when they are needed.
‘In order to deliver the required amount of spectrum, it will have a dedicated amount of licensed spectrum with high quality of service and then use the unlicensed spectrum on an opportunistic basis to supplement the data rate when it’s available,’ said Grace.
The spectrum will be divided into frequency bands and time slots, and then the base stations will speak to each other to organise how capacity is divided up without interference.
‘One of the big things that 4G will require because it is relatively complex is to be a self-organising network,’ said Grace. ‘Artificial intelligence will be used to learn about the environment and change the behaviour of devices in a controlled way.’
Trials
BuNGee will provide one option for mobile network operators, which are already researching the best ways to provide a 4G network.
O2 has been running a trial network at its headquarters in Slough, Berkshire, since March 2010 and has studied what technology would be needed to provide capacity as 4G takes off.
‘Our conclusion is that small-cell technology, as we go through this data tornado, is absolutely essential,’ said Andrew Conway, O2’s head of radio engineering.
‘We’re talking about radiuses of 50m and below compared with the several kilometres that we have now with typical macro base-stations. I think we’re at an inflection point now where this new data coming along starts to dictate an architectural change.’
Much of the hardware O2 is installing now is 4G-ready, but it is also developing software that will make it easier to upgrade the network in the future and reduce the amount of central monitoring needed.
‘There are some real assets coming along called self-optimised networks, which are networks that looks after themselves and take care of a lot of the parameters for optimisation,’ said Conway.
‘When you add a new base-station to the network it will follow a plug-and-play model where all of the parameters are downloaded to it and all of the data is sent back to the network performance centre in a seamless way.’
Definitions
4G is officially defined by the UN’s International Telecommunication Union (ITU) as a mobile service with a peak transfer rate of at least 100Mb/s, although actual speeds are likely to be in the region of 10 to 50Mb/s. By comparison, 3G services typically run at 1 or 2Mb/s.
The engineer
