NI LabVIEW and NI USRP Hardware Accelerate Cognitive Radio Research

Demonstrate that limited sources of radio spectrum can be successfully and cost-effectively utilized by both primary and secondary users.

solution:

Using NI Labview software and NI USRP™ (Universal Software Radio Peripheral) hardware to create a flexible real-time test platform, a cross-platform cognitive radio demonstrator was developed that combines spectrum sensing with a geolocation database to demonstrate efficient spectrum reuse.

"The seamless integration between NI USRP devices and LabVIEW software, as well as the creation of an intuitive user interface to present this research, will help other engineers and policymakers gain a deeper and more comprehensive understanding of this project."

——Paulo Marques, COGEU

Meeting today’s data consumption needs

As part of the European Commission's Seventh Framework Program, researchers from eight EU countries formed the COGEU project team to study cognitive radio systems to enable effective sharing of TV white spaces (TVWS) across Europe. Ultimately, spectrum reuse will reduce the cost of wireless connections and meet the growing demand for high-data-rate wireless devices. The COGEU team is working to transition the concept of spectrum reuse from concept to simulation and then to real prototypes, ultimately achieving the goal of influencing public policy from an economic perspective.

Figure 1: Graphical User Interface in Run Mode

Actual algorithm prototype

For the TV spectrum, there are two types of primary user transmissions: broadcast TV and Programming and Special Events (PMSE) equipment. The location of the broadcast towers is known and covers a certain geographical area (called the exclusion zone) near the TV transmission towers (multiplexers). COGEU, in cooperation with the German broadcasters, has developed and promoted a TVWS geolocation database for the Munich area, where real protection standards are in place for commercial digital TV receivers. The geolocation database stores a list of empty TV channels for each geographic pixel; however, many PESE applications (such as wireless microphones) occupy these TV channels, and the time, frequency and location of these applications cannot be predicted. This behavior increases the difficulty of exploring valuable TV bands that can be used for other applications. This is because PMSE systems do not have a standard waveform, so blind detection techniques are needed to determine the presence of PMSE devices without knowing any signal information in advance.

The COGEU platform demonstrator uses local PMSE sensing to cross-check information from the TVWS geolocation database. Next, the researchers determined through simulation that two methods, covariance absolute value (CAV) and blindly combined energy detection (BCED), outperform other forms of PMSE detection. PMSE sensing algorithms are integrated into the COGEU prototype. Real-world experiments show that CAV and BCED algorithms perform better than standard energy detection (ED) algorithms in evaluating the gain from more advanced detection algorithms. This method can sense PMSE signals with a signal-to-noise ratio of -17 dB in a Rayleigh channel with a sensing time of 100 milliseconds, a detection rate of 90%, and a false alarm rate of 10%.

System installation

We used a graphical system design approach in this project, integrating the GPS geolocation receiver, the NI USRP device that handles cognitive radio, an Internet connection to the geolocation database, and a GUI (Graphical User Interface) through LabVIEW system design software. The seamless integration between the NI USRP device and LabVIEW software, as well as the creation of an intuitive UI to showcase this research, can help other engineers and policymakers understand the project more deeply and comprehensively.

Until now, cognitive radio sensing based on USRP software defined radios has been implemented using GNU Radio open source software. The need to integrate different technologies and protocols, such as online access to the TVWS geolocation database, made LabVIEW an ideal platform for prototyping and proof-of-concept demonstrations of the COGEU system. In this project, we used many features of LabVIEW, including math operations, signal processing, NI USRP software drivers, and connectivity and data communication tools. The sensing platform consists of an NI USRP, a GPS receiver, and a host computer with LabVIEW installed. The NI USRP-2920 configuration provides a tunable radio frequency from 50 MHz to 2.2 GHz. The host computer is a laptop computer with Windows operating system and wireless access to the network, connected to the NI USRP radio via Gigabit Ethernet. The GPS device is connected to the host computer via Bluetooth. A commercial tunable FM wireless microphone is also used.

in conclusion

LabVIEW and the NI USRP hardware platform were key tools in this research project, helping the team quickly develop the first testbed of its kind.