In Home Propagation
The primary aim of this study was to determine the usefulness of a range of different frequencies between 500 MHz and 5 GHz for providing in-home wireless coverage. The study was intended to be application-neutral (e.g. the network might be used for audio/video distribution, or for computer networking), but used the 802.11n wireless networking standard as a representative example.
The study only covered cases in which both the transmitter and receiver (e.g. the access point and computer in a Wi-Fi network) were in the same building. It did not assess in-home coverage of transmitters situated outside of the building.
Within the home, media is often distributed across a number of devices, such as computers and set-top boxes, and consumed on anything from high definition TVs to tablets and smartphones. There is, therefore, an increasing requirement for higher speed wireless connectivity within the home.
Wi-Fi is integrated into many consumer devices already. The most common frequency band used by Wi-Fi equipment is 2.4GHz, a licence exempt band shared with a number of other technologies and devices, including Bluetooth. Given the proliferation of Wi-Fi equipment and the relatively limited amount of spectrum available in this band, there is the potential for congestion and interference to occur. However, the Wi-Fi family of standards also provides for operation in a range of relatively unused frequencies around 5GHz and newer devices are now available that support operation in both the 5GHz and 2.4GHz bands.
Looking ahead, standards are being developed that will lead to Wi-Fi devices using spectrum in UHF bands IV and V, i.e. spectrum between 470 and 790MHz made available by the move from analogue TV to more efficient digital TV standards. Access to these so-called white space frequencies will be contingent on not causing harmful interference to existing services, but has the potential to further increase the amount of spectrum available to Wi-Fi devices.
Given the potential for Wi-Fi devices to operate across a range of frequencies, we commissioned a study to investigate the relative suitability of the bands.
The study measured both path loss using continuous wave (CW) transmissions at all four frequencies and throughput obtained using representative 802.11 equipment at 2.4 and 5.7 GHz. The latter were extrapolated to provide estimates of throughput of equipment operating at 500 and 800MHz.
Measurements were carried out in the winter of 2010/2011, in a selection of houses broadly representative of the UK housing stock. The CW measurements were made simultaneously at four frequencies, with continuous logging of signals received at a 'hub location' from a transmitter carried around each room of interest. Measurements of throughput were made using standard 802.11n equipment.
In the course of the measurements, the following observations were made:
- Coverage, defined either in terms of 'points where connection was possible' or 'throughput speed attained' was invariably better at 2.4 GHz than at 5.7 GHz.
- The statistics of CW signal variation within rooms were similar at all four frequencies.
- No statistical difference was observed between the coverage to points around the room perimeter and the coverage within the entire room.
- In general, there was no significant difference in coverage with interior doors open or closed, although one house did exhibit a slight excess loss at 5 GHz with doors closed.
- Coverage at 500 and 800MHz was broadly better than at the higher frequencies
Ofcom's technical programme enables us to keep up to date with technologies and trends, so that we can be in the best possible position to execute our regulatory duties. In many cases, we do not conduct investigations in-house but make use of external resources, such as private commercial organisations, university departments and government funded research institutions. These reports present the findings of technical work conducted on Ofcom's behalf. The opinions and conclusions stated within these reports are those of the organisations who conducted the work and may not reflect the view of Ofcom or imply any future policy work in related areas. Ofcom is not responsible for the content or accuracy of these reports.