Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- About the author
- 1 The world of machine communications
- 2 The need for a new standard
- 3 Working in white space spectrum
- 4 Weightless in overview
- 5 The network
- 6 The MAC layer
- 7 The physical layer
- 8 Further functionality
- 9 Network design and capacity
- 10 Application support
- 11 In closing
- Glossary
- Index
- References
3 - Working in white space spectrum
Published online by Cambridge University Press: 05 April 2012
- Frontmatter
- Contents
- Preface
- Acknowledgements
- About the author
- 1 The world of machine communications
- 2 The need for a new standard
- 3 Working in white space spectrum
- 4 Weightless in overview
- 5 The network
- 6 The MAC layer
- 7 The physical layer
- 8 Further functionality
- 9 Network design and capacity
- 10 Application support
- 11 In closing
- Glossary
- Index
- References
Summary
Defining white space
Most of the spectrum below 10GHz across most of the world is allocated for particular applications and assigned to certain users. These include broadcasters, mobile phone network operators, defence departments and many, many more. The net result is that there is little obviously spare spectrum, particularly in the preferred frequency bands between around 300MHz and 3GHz where propagation is favourable but antennas are conveniently small. However, measurements of the actual utilisation of this assigned spectrum suggest that it is typically only used in around 20% of the locations. Such measurements undoubtedly underestimate usage but nevertheless it is clear that there is some potential for more efficient use of the spectrum.
One way to visualise where there might be underused spectrum is to plot on a map the strength of signal from the licensed user of that band. If colours are used to represent signal strength then those parts with no coverage at a given frequency will be uncoloured and appear white on a black and white map. Hence the term ‘white space’ for areas where there is potential for others to use the spectrum.
- Type
- Chapter
- Information
- Understanding WeightlessTechnology, Equipment, and Network Deployment for M2M Communications in White Space, pp. 20 - 47Publisher: Cambridge University PressPrint publication year: 2012