As the number of wireless applications and technologies increases, it is getting harder to allocate available spectrum to accommodate them all. The quality of users’ experience of wireless service is also affected by crowding more devices into the same spectrum, leading to slow transfers or even failure. For example, a sensor network for an automated home could be interfered with by a Wi-Fi network in the same building. And as different countries allocate different spectrum to devices type, these need to be able to work with more than one system so that they can operate across borders.
A solution could be ‘cognitive radio’, ‘cognitive networks’ or ‘software defined radio’ – advanced technologies that allow a wireless link or a wireless network adapt itself to different device applications and to changeable wireless environments.
By including a cognitive radio card, devices can work with varying standards at the physical level of wireless communication, adapting to different protocols for medium sharing, advanced spectrum sensing and other changing conditions. These abilities make it possible for devices to adopt different parts of the spectrum according to availability.
But there’s a catch. Developing and testing new cognitive wireless solutions requires a lot of specific, and often expensive, equipment, putting this process out of the reach of smaller-scale developers.
What if this equipment was available for every interested researcher? Thanks to the EU-funded CREW project, a set of cognitive radio and cognitive network testing facilities have been opened up to academia and industry.
STRENGTH IN NUMBERS
CREW creates a federation of wireless test bed facilities and experimentation tools from five institutions:
- iMinds, Belgium (w-iLab.t, a heterogeneous ISM test environment)
- Technische Universität Berlin (TWIST, a sensor network test environment for indoor wireless)
- Technische Universität Dresden (an LTE cellular test bed)
- the Jožef Stefan Institute, Slovenia (LOG-a-TEC, a sensor network test environment for outdoor wireless)
- Trinity College Dublin (the CCVTR’s IRIS, a cognitive radio test bed for licensed bandwidth, including TV bands).
From the commercial sector, the project also includes Thales, France (providing a transceiver API), IMEC, Belgium (with a state-of-the art sensing engine) and EADS, Germany (managing applications testing).
Users can access all of the federation’s software and hardware facilities through a single portal. There are three levels of testing: single test bed testing, testing across two linked parts of CREW, and testing across multiple parts of the federation.
Each or a combination of these levels allow users to develop products to work across different scenarios. CREW also provides benchmarks, realistic training data and controlled testing conditions, to help users evaluate results from reproducible experiments and performance testing.
Feedback from experimenters has been very positive. Researchers have welcomed access to state-of-the art equipment and the opportunity to test and validate advanced cognitive radio technical developments. They said that overall, access to the federation helped them learn a lot about using test beds.
Started in 2010, the project has carried out several of its own experiments, such as work on wireless communication in airplane cabins by consortium member EADS. It has also organised three open calls, attracting researchers from academia as well as industry.
The first open call attracted three experiments:
- sensitivity of spectrum sensing devices and wireless environment measurements (Durham University, United Kingdom)
- clear channel assessment agent in a CSMA MAC using IRIS modular software platform (Technische Universität Ilmenau (Germany)
- collaborative spectrum sensing (Tecnalia, Spain).
The second open call was organised in 2012 and resulted in four testing and validation projects:
- power consumption and latency measurements of spectrum sensing devices (University of Thessaly, Greece and National ICT Australia)
- optimal usage of TV white spaces with a geolocation database (CMSF-Sistemas de Informação and Instituto de Telecomunicações, Portugal)
- fast switching (on the fly changing) of MAC protocols and cognitive radio control signalling (Consorzio Nazionale Interuniversitario per le Telecomunicazioni, Italy)
- on-the-fly changing of cognitive radio control signalling (WINGS ICT Solutions, Greece).
More recently, the third open call, from 2013 to mid-2014 allowed smaller experiments. Seven of these, from academic and industrial research teams throughout Europe, have been accepted by CREW.
IT’S A RESULT
Overall, CREW allowed researchers to calibrate diverse spectrum sensing hardware in different physical environments provided by the different individual test facilities of the federation.
The project shared data from the experiments, benefiting other researchers. For example, the measurements performed by the University of Durham improved understanding of the wireless propagation properties of different physical environments.
Researchers also found the facilities extremely useful. In particular, they said that the interface for controlling softwaredefined radio hardware platforms provided better performance than previous radio drivers they used and that CREW’s modular software architecture for building highly reconfigurable radio networks (IRIS) was extremely easy to use, well documented and resulted in stable, bug-free software.
They also found that the framework for controlling wireless test infrastructure is very powerful. As well as describing and running experiments, it could be used for radio and network control as part of the solutions under test.
In the future, external experimenters will play a more important role, as the CREW facilities are now entering into an open access phase. Different access rights, permissions and tariffs could be introduced for different types of users (CREW core and open call partners; best effort external experimenters; premium external experimenters).
In its final year, the project – from October 2014 to September 2015 – will focus on ensuring the sustainability of the CREW solution. This year will be used to assess its long-term future and ensuring access to its facilities. Policy makers, funding bodies, other research projects, and other FIRE facility projects like Fed4FIRE will all have a role in sustaining the CREW facilities.
But whether the project continues, moves to the Fed4FIRE project or dissolves, one thing is sure – bringing together Europe’s best minds to work together on a solution is helping wireless technologies get along.