As wireless technology becomes more pervasive in the lives of everyday citizens, the electro-magnetic spectrum becomes increasingly over-crowded. Driven by escalating demand for mobile data capability, experts in the wireless industry are scrambling to find techniques to satisfy these needs with the limited RF. It is clear that technology must evolve to use this spectrum more efficiently. This topic was discussed in a recent blog by the New York Times, which features Martin Cooper, former VP of Motorola and co-designer of the first cell phone.
In this blog, the expert discusses several technical strategies that would allow more efficient use of spectrum. A few of the leading methods considered are femtocell basestations, cognitive radios, and smart antenna technology. Femtocell basestations are small, low-power basestations that might use an individual's internet connection for backhaul. Use of femtocells essentially reduces the geographic footprint for a given cell phone channel, thereby allowing more cells to exist in a given region. Cognitive radios observe the spectrum and make informed decisions on what frequencies to use for operation. This allows users to exploit unused spectrum when it is available, without necessitating complete consumption of that spectrum at all times. Finally, smart antenna technology can be used to perform adaptive beamforming or cancellation, allowing co-channel operation of more users in one geographic area.
So, with this topic receiving attention from people like President Barack Obama and coverage by notable publications like The New York Times, this is a good time to ask the question – how has the USRP product family contributed to all of these technologies? A few good search terms in Google yield hundreds of answers
Search: usrp cognitive radio
Search: usrp femtocell
Search: usrp antenna array
Just in case you don't want to read through a bunch of search results, I've summarized how the USRP product family has contributed to these technologies:
First, USRP devices have been the platform of choice for the experimenters and developers of the OpenBTS project. OpenBTS is an open-source GSM base station implementation. The USRP platform has been deployed as a real-world cell phone base station at events like Burning Man and in developing states such as Niue. There are also a number of developers using the USRP software defined radio to implement various portions of UMTS, LTE, and other cell phone standards. Recently, the USRP B100 has become a popular selection for these applications.
You may have seen some of our recent announcements that are related to cognitive radio development with the USRP platform. Shared Spectrum Corporation recently released the Spectrum Sensing Toolbox for use with theUSRP Embedded Series. This software leverages the embedded processor and DSP of the USRP E110 to detect various signal types including narrow-band interferes and broadcast television stations. Of course, many developers have implemented a variety of cognitive radio algorithms with the USRP platform.
Last but not least, the MIMO capability of the USRP Networked Series offers an easy and low-cost way to develop multi-element antennas systems - smart antennas. With plug-and-play 2x2 MIMO capability, and NxM MIMO expandability, the USRP N200/N210 is used to create very large antenna arrays. We know of a few applications that used systems larger than 12x12. The arrays have been used for adaptive beamforming and notching, as well as angle-of-arrival estimation.
In short, the USRP product family has, and will continue to be, a platform that leading contributors use to develop the technologies that improve the spectral effeciency of our wireless devices. This is an important matter for the future of wireless communications, and we are very happy that we can play our small part as we supply quality products for developers.