A report commissioned by communications regulator Ofcom is understood to recommend that UWB should only be permitted in Britain if service providers take measures to prevent interference with other wireless technologies.
"Ofcom has come to the conclusion that the economic benefits of Ultrawideband far outweigh the potential interference issues, but it plans to take a tougher stance on the technical specification under which UWB can operate," said a source familiar with the report.
It is believed that 3G operators have pushed for these tighter controls, claiming that their high-speed mobile networks could be disrupted by UWB.
The report, written by Mason Communications and DotEcon, is called Value of UWB Personal Area Networking Services to the United Kingdom.
It is expected to be made public later this month, at which point Ofcom will then seek comment from the industry. As it is a third-party report, Ofcom is under no obligation to accept its recommendations but a decision to reject such findings would be unusual.
Unlike Wi-Fi and Bluetooth, for example, UWB is not restricted to operating in a single small area of spectrum. Instead it spreads a low power transmission over spectrum used by other wireless technologies. This has led to concern that UWB could cause interference.
UWB regulators address this by specifying a mask - a graph showing how much power a UWB transmitter can radiate in each area of the radio spectrum. Most power is concentrated in the central part of the graph - the inband portion - with much stricter restrictions on radiation in the outband part on either side.
Two years ago the US regulatory authorities provisionally approved UWB with a mask that effectively restricted UWB transmissions to the same levels as ordinary non-transmitting consumer electronic equipment leak in normal operation. In particular, care was taken to prevent interference with the weak signals encountered in GPS satellite navigation services and other navigation systems. Although no UWB products are yet on the market in the US, manufacturers report that pre-production tests show no significant interference with any services.
Ofcom is likely to allow the same inband power levels, but with even lower levels in the outband -- which will include the bands used by 3G operators.
"Ofcom understands that UWB is a concern for some in the industry, and will take this into account when designing its own mask," said the informed source.
It's not yet clear whether these restrictions will hamper UWB deployment in any way, as manufacturers are likely to have to adapt their equipment to comply with Ofcom's mask -- should it indeed be implemented.
Early versions of the report seem to have been circulating in the industry ahead of its publication. Intel appeared to jump the gun last month when it issued a statement welcoming its publication, even though this isn't expected to take place until around 15 November.
"We agree with and support the conclusion that UWB has the potential to make substantial contributions to the UK economy, as it will in the US, over the next several years and Intel believes that similar benefits are possible for countries worldwide," said Kevin Kahn, co-director of the Intel's Communications Technology Lab.
"We also recognize that a great deal of additional work and evaluation will be required to make those worldwide benefits a reality."
Intel has been very active in UWB development, promotion and regulatory lobbying in the US, although entrenched disagreements between the two major industry groups involved in standardisation -- Intel and TI versus Motorola -- have effectively halted IEEE efforts to create a single standard.
Rupert Goodwins contributed to this report