TV White Spaces offers two potential benefits: immediate use of unused spectrum for rural area deployment and better overall use of existing spectrum. Africa currently has two active trials, one in Kenya (sponsored by Microsoft) and a second in South Africa (sponsored by Google). This week Russell Southwood looks at the second of these two trials to see why it is different from the first one and the potentially revolutionary implications of managed spectrum.
The TV White Spaces trial in South Africa started at the end of March this year and has three partners, Google, the Wireless Access Providers Association and university network organization, TENET, which is providing the implementation. The latter already provides the backhaul to a not-for-profit schools network in South Africa that are also partners in the trial. This consortium bulk-buys and resells ISP connectivity to these schools. The holders of the conditional spectrum licence for the trial are Government research institute CSIR, which will also monitor for interference during the trial. WAPA member Comsol Wireless Solutions is responsible for the installation, configuration and maintenance of the project.
The trial is connecting 10 schools in Cape Town with 3 base stations located on top of Stellenbosch University Medical School. As Arno Hart, Whitespace Manager, TENET explains, Cape Town is a good place for a trial. It has the combination of being a busy broadcast market and a fairly challenging topography which means that there are lots of TV transmitters.
The trial has two main objectives: to demonstrate that the managed spectrum technology can operate in this kind of environment without interfering with TV broadcasts and to encourage the regulator, ICASA, to accelerate access to managed spectrum.
The majority of WAPA members currently make use of licence exempt frequencies in accordance with the ICASA Frequency Licence Exemption Regulations 2008. It is however recognised that this is not a sustainable solution, given the pressure under which these bands are coming.
WAPA is promoting the development of a sustainable frequency-sharing model in South Africa and believes that this is a key intervention in raising spectrum efficiency and providing opportunities for new entrants. This trial is set to demonstrate that TVWS spectrum represents an immediate win that can be taken advantage of by the regulators. Says Geerdts, “WAPA looks forward to a greatly improved frequency regime which we can be proud that we contributed towards improving.”
The three base stations in the trial are connected through a 10 GB fibre backbone that connects to one of TENET’s clients. The base stations used are pre-production models from Carlson that has software that uses an FCC-type database of spectrum provided by Google. The software looks for what spectrum is available and chooses it. One of the things about even legally allocated spectrum is that it is only used for a relatively small proportion of the day.
The trial is operating in the UHF 490-550 MHz range. There are 10 channels in this range and the trial is using the odd numbered channels and the TV broadcasters are using the even numbered channels.
There are 3-4 schools per base station, giving download speeds of 1-10 mbps. According to Hart, a speed test conducted at the launch showed that 4 schools were getting 5 mbps download speeds. Some of the trial schools already have ADSL lines and the trial is therefore delivering a supplementary service. All the schools are primary and secondary Government schools and the service is being provided for free to the schools.
The trial will last for 6 months but the intention is to keep the network alive and make the business case for future roll-outs. Hart believes that it could contribute to the creation of a “Wi-Fi city”:”I hope the chip-makers will get into this space so that managed spectrum can function in urban areas.” One aspect of its importance lies in its ability to redeploy unused spectrum for the user almost in real time.
The really revolutionary possibility for TV White Spaces and managed spectrum falls beyond the remit of either trial. There is equipment that has the ability to measure the time used by different operators in each of the different spectrum channels.
So imagine if you will a world in which operators hire spectrum on a time basis for a fee to be established. The charging framework for this would be complicated but not impossible. It would need to balance between not punishing the big users but also offering the minimum entry barriers to new operators. So every operator would be “pay-as-you-go” and there would be a much higher usage of spectrum. It would also ensure that there was no strategic purchase of spectrum to keep out competitors or for onward sale.
The obstacle to this rather different world is that Governments everywhere and African Governments are no exception, see spectrum sales (particularly through auctions) as a tax cash cow. Unfortunately what you extract in tax from operators will be passed on in some way to the individual and corporate users to whom the bandwidth is delivered. If you want low cost broadband – both in rural and urban areas – then Governments will have to start seeing that charging large amounts of money may simply entrench large players with deep pockets and act as a barrier to this objective.