Researchers from Microsoft (NASDAQ:MSFT) and the Chinese University of Hong Kong (CUHK) are touting an alternative to geo-location technology for detecting available TV white space (TVWS) spectrum within indoor spaces.
"The geo-location approach has been studied extensively. While it does work, it has severe limitations," said Minghua Chen, a CUHK professor in the department of information engineering. "As an alternative, we have developed a new system, WISER, that uses sensing technology in a more efficient and cost-effective way than ever before."
WISER, is a somewhat creative acronym for White-space Indoor Spectrum EnhanceR. It is designed to identify and track as much TVWS spectrum as possible within urban, indoor locations without causing interference to spectrum that is in use.
TVWS--the unused portions of TV spectrum--can be used for unlicensed wireless communications. But TV band devices (TVBDs) are often required to use dynamic spectrum access (DSA) technologies, which query a geo-location database to determine available frequencies in particular location. Google (NASDAQ:GOOG) is among companies operating such a TVWS database system in the United States, having won approval for operation from the FCC's Office of Engineering and Technology earlier this year.
Microsoft contends that approach can be expensive and difficult to implement. Further, the company argues that there is often more spectrum available for use than indicated by a geo-location database, "especially in metropolitan cities such as Hong Kong where the wireless environment is complex."
This is especially true indoors, which is a critical shortcoming given that 70 percent of the demand for spectrum comes from indoor environments.
According to Chen, CUHK and Microsoft first identified the indoor TVWS availability issue three years ago and have been studying the issue since. "On average we found 40 percent more TV spectrum to be available indoors," Chen said.
WISER is designed to make use of this additional spectrum, and a prototype has already been built and tested in the Ho Sin Hang Engineering Building on the CUHK campus.
According to a blog post by Ranveer Chandra, senior researcher at Microsoft, WISER differs from other spectrum sensing technologies in that it "optimizes the position of a limited number of sensors," allowing researchers to "control costs and maximize effectiveness, without losing out on accuracy."
"Our results show that WISER can identify 30 to 50 percent more indoor white spaces than other approaches," Chen said. "With proper regulation in place, any interested building could adopt WISER to optimize wireless communications using TV white spaces."
Chandra noted that WISER techniques can be applied beyond TVWS for dynamic spectrum access in other spectrum as well.
TVWS is available for unlicensed access in the United States and Finland. Further, Singapore's Infocomm Development Authority recently wrapped up a consultation on white spaces, and UK regulator Ofcom is preparing to conduct TV white spaces pilots and has said the technology could be fully rolled out during 2014.
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