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Ofcom studies ways to advance license exempt spectrum

UK regulator Ofcom has launched a series of technical studies aimed at enhancing license-free access to the radio spectrum.

According to Ofcom's website, their "review will include examining the possibility of raising the allowable power levels" in the 2.4 and 5 GHz bands, estimating the economic gains produced by license exemption, and analyzing whether license exemption can be the default policy above a certain frequency.

"Changing the regulation of these applications could bring about greater flexibility in their use, and therefore improved spectrum efficiency. The most obvious and immediate potential applications could be in the provision of wideband to rural areas of the UK," notes Ofcom.

Contracts have already been signed for the following research projects:

• Licence Exempt Application Specific Bands: "The purpose of this study is to investigate the pros and cons of having dedicated bands for specific [licence exempt applications]... End date: December 2006
• Economic Assessment of the value of LE Bands: "...very little is known about the economic value of LE spectrum. So Ofcom has decided to commission a study to estimate this value... Step 1: assess global trends in use of LE spectrum. Step 2: predict demand for key LE bands and applications to 2020 in the UK. Step 3: quantify the current economic value of LE spectrum in the UK. Step 4: predict the future economic value of the LE bands over the next 15 years. Step 5: assess the costs and benefits which different levels of harmonisation of LE spectrum might bring to the UK in future... [The] project is expected to conclude in October 2006."
• An Investigation of the Use of Wireless for Last Mile Communications: "The purpose of this study is to investigate the use of wireless technology as an alternative for the provision of the last mile communications to the home. In particular, this might focus on technologies such as mesh in a mix of licensed and unlicensed bands... End date: December 2006."
• Permitted Interference and EMC Limits Above 1 GHz: "Electronic equipment is continuing to operate at faster clock speeds with PCs now operating at speeds exceeding 3 GHz.... Ultra-Wide Band (UWB) and increased use of Short Range Devices (SRDs) will also add to the need to define and control the quality of the spectrum above 1 GHz... There are currently no agreed standards for unintentional electromagnetic (EM) emissions from ITE equipment above 1 GHz in Europe... This project is expected to conclude in August 2006."
• Higher Frequency bands for Licence Exempt Applications: "A key outcome from this study is to answer the question as to whether all spectrum above a particular frequency should be licence-exempt and if so, what this frequency should be... End date: December 2006."
• Understanding the Scope for a Power Increase for Wireless Broadband Access at 2.4GHz & 5.xGHz: "The primary objective... is to assess the options for revising the regulation of license exempt applications (including power levels) to promote use particularly where spectrum is currently under used. The secondary objective of the work programme is to explore the use of higher powers in licence exempt applications in order to provide wireless broadband in rural areas..."

This last study has already generated a report by Scientific Generics Ltd., which was released on 10 May. Some of its findings:

• it would be advantageous to depart from the European practice of defining power allowances in terms of EIRP (effective isotropic radiated power). Instead, the report suggests defining the antenna gain and allowed transmitter output separately. The aim is to encourage more flexible use of sophisticated directional and sectorized antenna systems (e.g. MIMO).
• In the 2.4 GHz, band, the current power allowance of 100mW EIRP would be equivalent, in the new definition scheme, to a transmitter output of 50 mW conducted into an antenna with 3dB gain. The study recommends increasing this allowance in rural areas to a transmitter power output of 500mW and a maximum antenna gain of 20dBi (= 50W EIRP).
• However, the UK Ministry of Defense is said to use the 2.400 - 2.450 GHz band in many rural areas. No economic analysis was made of the cost to MoD of dealing with interference from higher power WLANs. But the study recommends limiting any power increase to the 2.450 - 2.4835 GHz band, which MoD does not use.
• The report also suggests requiring either registration or the inclusion of a GPS receiver to ensure that higher power systems operate in the 2.450 - 2.4835 GHz band only in rural areas.
• In the 5.725 - 5.875 GHz band, "light licensing" of broadband access systems would be replaced by license exemption.

We understand that Ofcom will launch a public consultation in a few weeks based on these recommendations.

[Wireless: 31 May 2006]