TV White Space (TVWS) frequencies are becoming a real world test laboratory of dynamic spectrum sharing. A challenging aspect of 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.
TV White Space cognitive device operation may be permitted if (and only if) it does not interfere with incumbent services such as digital TV and PMSEs (e.g. Wireless microphones). White Space devices should either sense the presence of incumbent systems or make use of a geo-location database to determine which spectrum is unused in the vicinity. Current regulation in the US and UK are supporting the solo use of the geo-location database. However it is increasingly recognized that a solution based on exploiting spectral sensing coupled with geo-location databases allows a more effective use of TVWS. In particular, a geo-location database assisted by a low-cost and densely deployed spectrum monitoring infrastructure is a promising approach to protect dynamic incumbent systems, such as wireless microphones that are not registered in the database.
CMSF-SI work was to design and demonstrate the combination of geo-location spectrum database access with a spectrum-monitoring network made available by third parties. The core of the 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. A TVWS database was computed according to the algorithm and procedure describe in ECC Report 186, with a 200 m resolution grid. The communication with the geo-location database was implemented by a draft version of the IETF PAWS (Protocol to Access White Spaces).
The work assumed that PMSEs are not registered in the database (a common scenario in many EU countries) and therefore its protection completely relies on sensing. Once the PMSEs transmitter are detected by a distributed sensing algorithm, the TVWS geo-location database is informed and automatically removes from the 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.
Despite 5G emergence, deployment of Long Term Evolution (LTE and LTE-A) continues to increase globally, to meet the unprecedented demand for mobile broadband services. It incorporates innovations such as advanced Radio Resource Management (RRM), Self Organizing Networks (SON), small cell solutions, and many others which, collectively, provide increased capacity and data speed while reducing the cost per byte and overall expense of operating these networks. However, the development and deployment of LTE solutions present some unique challenges for the telecom equipment manufacturers and service providers, who need to address the increased complexity of these networks.
Thus, network operators, need to make performance tests and feasibility studies, before deploying the system in the field or before the release of new services. CMSF-SI has developed a software tool capable of simulating the operation conditions in a wide variety of scenarios related to the performance of the radio connection. This is a valuable tool to our customer, who uses it to test and optimize radio related algorithms and procedures, mainly carried out on the physical layer (link level) and in the network (system level) context.
Most available LTE simulation tools don’t take into consideration the Quality of Experience (QoE) that a certain service has, which in fact directly affects consumer expectations. With this in mind, our solution includes an LTE emulator, composed by the System Level Simulator (SLS) and the Real Time Link Emulator (RTLE) that can be used for testing the performance of several services under the conditions of a real LTE mobile network.
CMSF-SI has been researching Software Defined Radio (SDR) and Cognitive Radio (CR) technologies for the commercial and public safety sectors. CMSF-SI believes Reconfigurable Radio Systems (RRS) would be the drivers for the next step in the evolution of wireless communications. These technologies are seen by us as an enabler for the introduction of new users and applications in co-existence with incumbent uses in some frequency bands, such as, for example, TV White Spaces in the UHF band.
Even though there currently are substantial uncertainties relating to spectrum regulation and to the attractiveness for different stakeholders of associated business models, CMSF-SI intends to be at the forefront of experimentation with RRS technologies in the area of pre-commercial and commercial applications.
In a commitment towards the reseach community from who we have benefit so much, the majority of our software packages are released under GNU General Public License (GPL) , meaning the research community will have the freedom to run, copy, distribute, study, change and improve our software.