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Inside ‘white space’ broadband

“White spaces”” used for broadband Internet are still shrouded in mystery. This FAQ delves into what it is and how it can change Internet access.

Frequently Asked Questions (FAQ) on “”White Spaces””.

Q: What is spectrum?

Spectrum is the range of frequencies, which wireless devices can use to transmit or broadcast information. Spectrum is broken up into bands of different frequencies that are used for different types of devices and information. Some bands of spectrum are licensed by government regulators and set aside for military and public safety purposes as well as commercial applications such as radio, television and broadband Internet. In certain countries, other bands are set aside for unlicensed or license-exempt use. Common uses of unlicensed spectrum are WiFi networks and Bluetooth devices.

Q: What is white spaces technology and how does it work?

The term TV white space spectrum refers to unused frequencies in television broadcast bands. Television broadcasts occupy designated channels in the VHF and UHF bands, but not all the designated channels are in use for broadcast, giving rise to ‚””white spaces‚”” in which a channel that is not used for broadcast may be available for other purposes, like delivering low-cost, high-speed broadband access to unserved areas.

Q: Has this technology been tested?

Microsoft has conducted trials and commercial pilots in Singapore, the U.S. and the U.K. have proved that this technology works and that its use can have a dramatic impact on broadband access.

Notable TVWS case studies include networks launched in North Carolina and Virginia. Similarly, the commercial pilot in Singapore seeks to bring broadband and connectivity to areas where networks often fail from penetrating dense vegetation and challenging terrain to providing long-range wireless Internet coverage across the waters at the Singapore harbor.

Q: How far out in the future is commercial implementation of this technology?

This depends to a great extent on policymakers, who recommend laws and regulations. Assuming appropriate regulations are put in place, consumers will in due course notice the introduction of devices, applications and services which will make use of white spaces to deliver faster and better internet connections in many more places than they currently experience.

How does connectivity through white space technology compare with that of traditional internet delivery systems?

Operating at the same power levels afforded to current Wi-Fi devices (40 or 100 milliwats), a simple calculation shows about 16X fewer access points are needed in the UHF part of TVWS (600 MHz) to deliver the same coverage as Wi-Fi in 2.4 GHz. With the same number of access points offering four times the range, one can achieve sixteen times the coverage.

Fixed TV white space devices operating at higher power can provide multi-kilometer wide area connectivity akin to current 3G/4G wireless networks. For example, field trials in Cambridge, England confirmed that up to 8 Mbps net speed can be achieved over 5.5 km links, within an 8 MHz bandwidth TV channel. Better throughput was achieved closer to the base station. With non-contiguous and contiguous channel bonding an expected feature of second generation TV white space devices for example, taking advantage of the emerging 802.11af/ac Wi-Fi standard even better throughput can be expected.

Another key difference from traditional Wi-Fi is that white spaces devices will gain managed access to unused TV channels by providing their precise locations to a database which in turn provides channel lists along with other operating parameters, such as power, duration, and geographic boundaries. White space devices will only use those channels provided by an authorized white space database. If no channels are returned, a white spaces device will not transmit on TV band spectrum. With the ability to exchange information on channel utilization, throughput, packet loss, and other measures of quality, white space devices and databases will use this spectrum more intelligently over time.

Q: What infrastructure would the technology require?

The one essential infrastructure piece needed to deploy a TV white spaces network is a database. The database lets devices in the area know which spectrum is available for access in that location. Users will be able to purchase, install and operate their own networks. If a user would like to use TV white spaces access points in a home or retail environment (e.g., to create a hot spot), a broadband connection is needed to access the network (either wireless or wired). To use TV white spaces as a base-station complement, backhaul is needed (a high-capacity wire or wireless connection).

Q: Are white spaces entirely wireless or do users need to connect to a fixed line broadband network at some stage?

All TV white spaces infrastructure much connect to a fixed line at some point. However, TV white spaces provide enhanced flexibility over Wi-Fi. The user has increased options as to where to connect to a fixed line because of the propagation characteristics of TV white spaces: a user can connect at home, at a base station or the backbone of the network.

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