Spectrum allocations: a matter of balance

Janette Stewart/Analysys Mason
08 Jul 2011

It is likely that a combination of wired and wireless technologies will be required to meet ‘broadband for all’ ambitions. There is an expectation that further spectrum will be needed for mobile broadband systems, over and above that already allocated and in use.

A number of governments have published their views on how much additional spectrum might be needed – for example, the US government announced in its National Broadband Plan that in the next decade it intended to find another 500MHz of spectrum for mobile services. It has been estimated that the UK will require a similar amount of extra spectrum.

At an international level, the ITU Radiocommunication Sector (ITU-R) is responsible for reviewing frequency allocations every few years at World Radiocommunication Conferences (WRCs). Additional spectrum for mobile services is not on the agenda for the forthcoming WRC in 2012 (WRC-12), but it is expected that it will be considered at the following one (WRC-15).

Estimating the future spectrum requirements for mobile services is a complex issue, requiring consideration not only of the expected growth in use of mobile data services during the next decade, but also of various economic and market factors to determine the peak traffic load that mobile networks might need to accommodate.

International Mobile Telecommunications (IMT) is the name given to the family of 3G and 4G mobile standards defined by the ITU-R. IMT-Advanced describes the evolution of the original 3G standards towards 4G. Spectrum requirements for IMT systems were last considered by the ITU at the World Radio Conference in 2007 (WRC-07), with estimates of spectrum requirements based on a methodology defined by ITU-R Working Party 5D, which is part of ITU-R Study Group 5. But the significant increase in use of mobile broadband services means that forthcoming WRCs may need to revisit spectrum requirements. Another new methodology will likely need to be found to estimate future spectrum requirements.

Around 10 years ago, the ITU-R developed a spectrum calculation methodology (ITU-R M.1390) to estimate the amount of spectrum that IMT systems required, both then and in the future. The methodology was based on estimating system capacity, assuming traffic was carried over circuit-switched networks – typical of 2G mobile systems.

For WRC-07, a new recommendation was made (ITU-R M.1768), which defined a methodology for calculating spectrum requirements for voice and data services. This methodology is applicable to both circuit-switched and packet-switched traffic, and still provides a valid means of estimating total spectrum requirements.

However, we believe that future estimation models need to take account of various interrelated market and economic factors relating to 3G and 4G traffic types and loading which, taken together, will ultimately determine the economic traffic load per mobile network.

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