Decentralized Networking in White-space

White-spaces are frequencies that have been used, until the recent digital switchover, by analogue TV broadcasters. These frequencies are now available and large parts have been released (e.g. in US) for unlicensed spectrum access. White spaces are prime frequencies because they are low in spectrum and signals propagate far (unlike in ISM bands). Unlicensed and decentralized access has proven to be very successful and WiFi connections currently carry most of the world’s wireless data traffic. Thus unlicensed and decentralized White-space networking presents a unique opportunity that could potentially provide ubiquitous and cheap Internet access for everyone.

However, there are several design challenges to make a decentralized White-space wireless network work. Excellent signal propagation is both a bless and a curse. Since white-space signals propagate far, they will cause interference to a number of other White-space. The same issue in WiFi networking is much less pronounced because the signal propagation shorter. Dealing with the interference in an uncoordinated way on large scales is a major challenge. Another challenge is that the White-space spectrum is fragmented. White-space devices are secondary citizens and can use only chunks of spectrum that are not used by primary, registered users. These chunks are all around, a quality of each chunk is different at different times and for different users. It is not clear how to distribute available chunks to contending White-space nodes in an efficient and fair way.

The above mentioned problems are just illustrations of challenges lying ahead on the road towards ubiquitous White-space networking. The goal of this project is to deal with them and come up with technological solutions that would overcome the challenges.

Press Coverage
Tools for rapid prototyping of SDR MAC
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MSR People involved in the project
Alexandre Proutiere
Alexandre Proutiere

Dinan Gunawardena
Dinan Gunawardena