M2M communications over TV white spaces

Elena García Couto | Researcher

Nowadays, it seems almost impossible to live without our cell phone. Therefore, it is not surprising that even machines could communicate between them without any human interaction. And this, rather than a science fiction story, is real thanks to M2M or “Machine to Machine” technology.

With M2M we refer to those automatic communications that happen between devices in order to exchange information. Those communications involve an efficient exchange of a big amount of short messages. Besides this, they must satisfy some requirements: they must demand low cost and power, cover a big coverage area and must be able to handle lots of terminals and messages in a reliable and secure way.

There are many ways in order to deliver these messages, like the traditional mobile networks (GSM, GPRS, UMTS…) but there are also other choices like using free spectrum portions located in other frequency bands in order to not saturate that crowded networks. Cognitive devices are able to evaluate the electromagnetic spectrum availability, finding the unused regions of this spectrum (known as “white spaces“) and make use of them in an efficient way when they have information to transmit. Those portions vary in number and frequency depending on the location, and in recent years TV white spaces, arisen from the analogue switch-off, have become more well-known. There are many benefits of working at those frequencies, because signals at TV band have a very good propagation characteristics and, therefore, it is possible to increase the quality of the communications in rural areas with specific orographic conditions or even inside buildings. Besides this, these systems are more tolerant to obstacles between transmitter and receiver.

The advantages of using M2M communications over white spaces are borne out by the trials developed in Cambridge by the White Spaces Consortium (in which take part different companies including Microsoft, Nokia or BBC, among others). One of the experiments presented in those trials consisted in a successful prototype of sensorized waste containers around the city which used those frequencies in order to transmit their data. Cambridge is also the birthplace of the first standard for M2M communications over TV white spaces, named Weightless, in which Gradiant has participated as a part of the definition process.

For all these reasons, and given its experience in this kind of topics, Gradiant is currently working in this research line in order to develop low cost high-performance solutions to be used in the future smart city for different applications.

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