You may have seen the recent news that Ofcom has recommended to change the licence conditions in the “DECT guard band” after TalkTalk submitted a variation request. TalkTalk submitted the request because the company wants to deploy low-powered 4G technology in the UK in the 1781.7–1785 MHz frequencies, paired with 1876.7–1880 MHz.
This band is already allocated for mobile operators to provide 4G services within the EU, however, in the UK, this spectrum forms part of a ‘guard band’ between spectrum used by mobile networks and that used by cordless home phones. Within the UK this has been left unused to prevent interference between the two groups of users.
This variation would permit TalkTalk to deploy compliant 4G apparatus in the band, which it has owned for a number of years now, enabling it to deploy new broadband routers that feature a 4G mobile femtocell — without the need for (expensive) additional filtering.
Earlier this month, Ofcom consulted on plans to vary concurrent spectrum access licences in this band, and expressing its preliminary view that allowing low power 4G devices in this band would be acceptable and the benefits of this use would outweigh any small additional interference impact. Ofcom’s preliminary view cited three Real Wireless reports that were commissioned by TalkTalk to conduct an independent technical study into the potential interference with uses in adjacent bands.
Evidence of the impact of a potential interference was based on a measurement campaign and co-existence analysis based on Real Wireless’s extensive modelling capability. The test scenarios also spanned from small cell spectrum emissions; to impact on voice quality, dropped call rate and call hold times comparisons of a dense DECT network; and interference with a DECT-based baby monitor.
Based on these results, Real Wireless was able to propose to TalkTalk the changes to the licence conditions that were likely to be considered acceptable to Ofcom, and formed the basis of Ofcom’s recommendation.