TV white space is a general term for the geograph ical redundancies in the TV broadcast bands. The re-use of TV white space is of current interest due to the change to digital transmission in many parts of the world. This has led to the biggest re-structuring of the TV bands since their creation. The bands represent a prime section of spectrum, which currently has some geographical white space.This paper attempts to quantify the number of bands available in the south-west of the UK where digital switch over is now complete. It is shown that, in high and flat terrain, there is little spectrum free. This suggests that limiting access to this spectrum to large scale protocols, such as IEEE 802.22, would be inefficient in the UK. In areas of more complex terrain the number of bands increases significantly allowing short-range, local links.

Availability of television white space is of interest for developing new data networks which operate between licensed users. The practical sensing and computational modelling of this band has been the focus of study in this and a preceding paper [1]. In this paper a high spatial resolution was used to look at the areas that a single channel was available in moderately rough terrain in the UK. The size of areas which shared available frequencies was found to be small and potential problems with spot measurements were highlighted. The practical validation of the software model with a measurement campaign has been started, the early results of this show the model to be reasonably accurate in exposed areas with little building but at portable equipment heights in streets the model shows significant variation from measured results.

White space radio networks have achieved acceptance in principal by radio regulators across the world. The challenges associated with accurately sensing the availability of the channel without knowing the details of the current shadowing environment have lead to a tendency toward requiring a geolocation database approach for determining available bands as was required by Ofcom [1]. This provides regulators with a central point of control from which they can ensure primary users are protected. However to provide the initial database a reliable and verifiable dataset for an entire country is required, at a high resolution (100 m cells is recommended in the UK [1]).In this paper such a model, based on the Parabolic Equation Model, is presented and the results of field trials to confirm the model validity are discussed.

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