Challenges for Industrial Development

 

 

1. Spectrum Planning in Each Country

Differences in local conditions and spectrum usage mean that each country has taken a different approach to White Space adoption. UK and the US, for example, have decided to make White Space available for unlicensed use after extensive research and testing. Japan however, is leaning towards a secondary spectrum transaction approach that the spectrum owners such as broadcaster can resell or lease their vacant spectrum to users. Differences in how the license is issued will decide the entry threshold for the industry. While an unlicensed approach will help industry development, it may also lead to chaos without effective management and industry self-regulation. Adopting a secondary spectrum transaction model will generate new spectrum brokering and transaction opportunities from both long/short-term leasing and resale as well as boost the utilization of vacant spectrum.

2. Geolocation System

Geolocation (e.g. GPS) is one of the key functions of White Space terminal devices. The device must identify and report its location to the back-end database, so the database can notify the device what channels are available at its location. One of the inherent limitations of GPS is the poor in-door or obstacle crossing reception. This greatly hampers the accuracy of current location interpretation and will be particularly acute for personal mobile/portable devices. Integrating a spectrum sensing function may alleviate the geolocation problem but will greatly increase the manufacturing cost and then hamper service adoption. Hence, a simple and cost effective auxiliary geolocation  solution is what the industry urgently needs to provide today.

 

3. Spectrum and Geolocation Database

The preferred approach to White Space detection and application for spectrum regulators and the industry has switched from spectrum sensing to the database model. Once a unified national spectrum and geolocation database is established, it can be made available to fixed and personal mobile/portable devices. It can also be used for other fields such as radar spectrum sharing, femtocell operation and even temporary sharing of 3G/4G spectrum among mobile operators, for example, telecommunication companies may reuse their vacant3G/4G spectrum in remote area by leasing or resale as the White Space approach, creating new business models and opportunities. The construction of spectrum and geolocation databases has therefore become an important issue.The content of the database will mainly consist of local spectrum usage and geolocation information. Apart from information on local broadcast spectrum usage, most data will need to be provided by the terminal equipment. The available spectrum and recommended power output is sent back to the terminal device. As the terminal device must periodically update geolocational data to avoid interference,the setting of the refresh frequency becomes extremely important. Data security and authentication are other key areas of development. The industry still needs to devise a way to prevent fake database and geolocation data from undermining information integrity. The US and UK governments both plan to transfer the responsibility of database setup and management to the private sector and this is a sought-after role for major international vendors. While not requiring a license indicates the government and operators may not collect fees from releasing or leasing the spectrum, the establishment of database by private sector may offer a source of revenue and create promising business opportunities in future White Space applications. 

 

4. Competing Technologies

Before White Space deregulation brings new possibilities for the communications industry, the relevant technical standards must be established first. Careful thought must also be given to guaranteeing the interoperability and co-existence with different technologies. A plethora of different standards based on cognitive radio technology including IEEE 802.22, IEEE 802.11af, IEEE 802.16h, IEEE 802.19, IEEEP1900/SCC41, ECMA-392 and ETSI RSS (Reconfigurable Radio Systems) has presented an immense market potential of different applications. Most of these standards have now been formally adopted.When compared to other standards, 802.22 is developed specifically for the TV spectrum and makes more effective use by taking advantage of the UHF/VHF spectrum. The approval of the standard does not necessarily mean that802.22 will dominate the White Space market however. The standard has been in development since 2004, and such along gestation process raises doubts about the marketability and future potential. As no alliance or forum has been formed to back this standard to date, many obstacles remain to overcome. The latest entry to the field is the IEEE 802.11af standard supported by the Wi-Fi Alliance that is still under development. Wi-Fi 802.11x wireless transmission technology is finding an increasing range of applications and the jump in demand for network connectivity from terminal devices represents it has gradually become an influential standard feature of consumer electronic devices in the industry. A White Space standard derived from this approach can generate synergies from integration with existing 802.11x standards and may well become the greatest competitor of802.22 standard in the future.

References:
1. "Overview of 802.22 WRAN Standard and Research Challenges", Zaw Htike and Choong Seon Hong
2. "Coexistence Problem in IEEE 802.22 Wireless Regional Area Networks", Raed Al-Zubi, Mohammad Z. Siam, and Marwan Krunz
3. IEEE 802.22 Wireless Regional Area Networks - Enabling Rural Broadband Wireless Access Using Cognitive Radio Technology - IEEE P802.22 Wireless RANs
4. "IEEE 802.22 Standard Approved for White Space Development", Hsien-Tang Ko, Chien-Hsun Lee, and Nan-Shiun Chu