Seize white space TV spectrum to fire Super Wi-Fi

Huang Jianwei and Chen Minghua

Huang Jianwei and Chen Minghua Since the turn of the decade, explosive growth of smartphones and bandwidth-hungry applications has turned radio spectrum, which carries mobile data, into an increasingly scarce resource. With mobile data traffic in Hong Kong growing 108% per year, it is increasingly challenging for the current 3G/4G cellular networks to fully satisfy the city’s demand for mobile connectivity.

Exploring the use of Super Wi-Fi—an alternative of standard Wi-Fi that provides faster and greater geographical coverage—could effectively ease the existing network capacity crunch.

Wi-Fi VS Super Wi-Fi

Super Wi-Fi is carried through unused television broadcasting frequencies or "white spaces". As such, it operates in an entirely different radio frequency band from standard Wi-Fi. The technology is more powerful because it can travel farther and penetrate more obstacles.

As an example, while standard Wi-Fi can support a 5Mbps/MHz transmission rate over 35 meters in an indoor environment, Super Wi-Fi can achieve the same rate over several hundred meters and hence cover a much bigger area. It is particularly well-suited to serving remote islands and cargo ships around Hong Kong. Currently, access points (APs) of standard Wi-Fi at the seashore cannot provide connectivity to nearby vessels. It is also very expensive to provide connectivity in isolated areas using cables.
Another key advantage of Super Wi-Fi is the ease of adoption. User adoption requires only mobile devices that are compatible with Super Wi-Fi. The cost of building these devices is also comparable with today’s Wi-Fi, and could potentially be cheaper.

Recycling broadcast frequency
Existing Wi-Fi spectrum is crowded and additional investment on APs will not bring substantial improvements in performance. Investing in Super Wi-Fi is expected to significantly increase the performance of wireless data networks by utilizing sizeable white spaces originally reserved for television broadcasting.

Today, 50-70% of television white spaces in Hong Kong are not used as signals are changed from analog to digital. This represents a huge public resource that is lying idle and yet under-utilized.
Globally, Super Wi-Fi is gaining traction, but Hong Kong is lagging way behind from many countries to capture this growth opportunity. The UK, USA, Canada and Singapore have all approved the unlicensed use of television white spaces. The Philippines have also planned a trial in Super Wi-Fi. But the Hong Kong Government has simply expressed interest in the technology, without concrete plans for adoption.

Super Wi-Fi is the future, and it is an opportunity for local business growth. Support from the government is important. Simply by opening up unoccupied frequencies in the local radio spectrum, as well as authorizing one or two white space geo-location database operators to trial this service, are going to bring significant benefits to local citizens.

To ensure the service is stable and reliable, the authorities can also certify operators that are capable of providing accurate information about the availability and quality of white space channels to consumers.
Moving from outdoor to indoors

In Hong Kong, more than 70% of data demand comes from indoors, which is also where Hongkongers spend most of their time.

Until recently, research on Super Wi-Fi has been focused on its application in outdoor environment. The Chinese University of Hong Kong (CUHK) recently made a breakthrough by developing a way for Super Wi-Fi to work reliably indoors.

Although technical challenges have been solved, mainstream commercial Super Wi-Fi service requires viable business models and a supporting ecosystem.

As part of the ecosystem, CUHK research team proposed the development of an “information market.” This market provides network information in relation to the channels availability, their quality and interference level. This service can be directly applied to the current television white space technology framework, without requiring additional hardware investment.

This offering is expected to bring a significant profit to white space geo-location database operators, while enabling mobile users' premium wireless communication service.

Standard Wi-Fi has become inefficient, and the adoption of Super Wi-Fi technology is an opportunity that Hong Kong should actively pursue. If the government and local businesses can capture this opportunity, they can maximize mobile connectivity for Hong Kong.

Huang Jianwei and Chen Minghua are associate professors with the Department of Information Engineering at The Chinese University of Hong Kong. Their research areas focus on networking theory, internet and applications, as well as wireless communications and networking.


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