This online demo showcases the combination of a spectrum geolocation database with a spectrum-sensing network. This work is part of an external experiment carried out under the EU research project FP7 CREW.

A challenging aspect of TV White Space (TVWS) use in Europe is that TV spectrum is not only occupied by fixed TV broadcasting signals. In addition to the TV broadcasts the spectrum is used by licensed Programme Making Special Event (PMSE) devices, e.g., wireless microphones.

In this CREW experiment we assume that PMSEs are not registered in the database (a common scenario in many EU countries) and therefore its protection completely relies on local sensing. Once the PMSEs transmitter are detected by a distributed sensing algorithm, the geo-location database is informed and automatically removes from the TV white space maps an exclusion region around the PMSEs location. In this exclusion area, transmission of cognitive users of the TV spectrum is temporarily not allowed.

The TV white space maps for Slovenia (Show white spaces) were computed according to the algorithm and procedure described in ECC Report 186, with a 200 m resolution grid. For a selected area, the white spaces availability data can be exportable to a log file and used in subsequent experiments by users of the CREW federation.

The sensor network used in the trial is operated by the Jozef Stefan Institute (JSI) and is available as part of the FP7 CREW federation (link). The core of the JSI testbed consists of a sensor network containing approximately 50 low cost nodes mounted on public lighting infrastructure in the Logatec city. The sensor nodes on light poles are equipped with different spectrum sensing and signal generation capabilities, including the VHF/UHF frequency bands. The nodes have IP connectivity and can be remotely reprogrammed according to the needs of the investigated use case.

The communication with the geo-location database is implemented by a draft version of IETF PAWS (Protocol to Access White Spaces). The main objective of this protocol is to allow a WSDs to request spectrum access to the geo-location database, and retrieve a list of available TV channel to operate as a secondary user. This demo includes a graphical user interface visualising the message flow between the database and the WSD (Demo PAWS).

A trial was carry out in the Logatec city (Slovenia) to assess the benefits of combining a white spaces database with a distributed sensing network in the coexistence between WSDs and incumbent systems. An important result is the ability of the geo-location database to automatically create protection areas around detected wireless microphones devices using real-time information from the sensing network (Demo Sensing+WSDB).

This experiment highlights the benefits and showcase the technical feasibility of dynamic spectrum databases, i.e., the combination of a pre-computed white spaces maps with real-time information from a distributed sensing network.

At regulatory level, the research results from this trial will help administrations to recognize the value of spectrum monitoring as part of the progressive approach to managing spectrum more efficiently.

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