Future of Wifi
Super Wifi or say TV White Space refers to the unused TV channels between the active ones in the VHF and UHF spectrum. These are typically referred to as the “buffer” channels. In the past, these buffers were placed between active TV channels to protect broadcasting interference. It has since been researched and proven that this unused spectrum can be used to provide broadband Internet access while operating harmoniously with surrounding TV channels.
In Electronics, referred by technical term as IEEE 802.11af, also referred to as White-Fi and Super Wi-Fi, is a wireless computer networking standard in the 802.11 family; that allows wireless local area network (WLAN) operation in TV white space spectrum in the VHF and UHF bands between 54 and 790 MHz. The standard was approved in February 2014. Cognitive radio technology is used to transmit on unused TV channels, with the standard taking measures to limit interference for primary users, such as analog TV, digital TV, and wireless microphones. In 2010, the FCC(US spectrum allocation authority ) made this highly effective yet underutilized spectrum available for unlicensed public use. With the use of a database manager and a White Space radio, these channels can be used to access broadband Internet connectivity.
White-Fi Concept
The basic concept behind White-Fi technology, IEEE 802.11af is that broadcast television coverage has to be organised so that space is left between the coverage area of different transmitters using the same channels so that interference does not occur.
Sufficient space has to be left so that even when tropospheric propagation conditions increase the distances over which signals can be received, interference does not normally occur.
This means that there are significant areas where these channels are unused and this leads to very poor spectrum use efficiency.
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| White-Fi Concept |
Salient Features
The table below gives a summary of the salient features of 802.11af technology.
| 802.11af Characteristics | Description |
|---|---|
| Operating frequency range | 470 - 710 MHz |
| Channel bandwidth | 6 MHz |
| Transmission power | 20 dBm |
| Modulation format | BPSK |
| Antenna gain | 0 dBi |
Benefits of IEEE 802.11af, White-Fi
There are many benefits for a system such as IEEE 802.11af from using TV white space. While the exact nature of the IEEE 802.11af system has not been fully defined, it is still possible to see many of the benefits that can be gained from White-Fi technology:
Better Coverage than Wi-Fi
While a traditional Wi-Fi router has a relatively limited range, around 100 meters under perfect conditions, and can be blocked by walls or other environmental barriers, TV White Space technology can cover an expanse of about 10 kilo-meters in diameter (100 times the distance)! This breakthrough technology was nicknamed “Super Wi-Fi” because of its superior range and ability to penetrate obstacles such as trees, buildings and rough terrain.
Non-Line-of-Sight (NLOS) Performance
Microwave links require line-of-sight (LOS) between the points being connected. In areas with rugged or forested terrain, the tall towers necessary to provide this line-of-sight connection make microwave an expensive and unfeasible solution. TV White Space technology provides an effective alternative to microwave by utilizing the lower-frequency UHF signals that can penetrate obstacles and cover uneven ground without requiring additional infrastructure.
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| NLOS Working |
Written by
Prince Hridayalankar
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