Over-the-Air Television Channels

TV Channels - VHF and UHF --> ~300 MHz
Each channels use 6-8 MHz (depending on country)
- Analogue channels need to be separated by at least one channel width as to avoid interference

Digital Television

White-Fi uses the free/whitespace of the 700 MHz spectrum for WiFi usage

Radios that can digitally reproduce different modes of radio.

Uses a DSP or FPGA.

Flexible, upgradable, cheaper, lower power consumption

Software Defined Antenna - small pixel elements configurable by software for the desired band
Universal Software Radio Peripheral (USRP)
- These chips / circuit boards exist but are not widely available

(The free/unused channels)

10 companies are authorised by the FCC to administer the TVWS database.

These companies can fetch data, register devices, synchronise databases and ultimately provide channel availability to devices

GDB - Geolocation Database
RLSS - Registered Location Secure Service
- Provides faster response to access points locally in a campus
- May be owned by the ISP
GDD - Geolocation Data Dependent
- GDD Enabling - Access points
- GDD Dependent - Other stations
PAWS protocol to access

700 MHz

Basic Channel Unit (BCU) - BCU - One TV Channel

Max 256-QAM
Max 5/6 Coding
OFDM similar to 40 MHz in 802.11 but downclocked by 7.5x
- 0.4μs GI in 802.11n -> 3μs in 802.11af (0.4x7.5=3)
- 3.2μs data interval -> 3.2x7.5 = 24μs
- Total symbol interval = 24 + 3 = 27μs
6MHz channel: 144 total subcarriers
- 108 Data
- 3 DC
- 6 pilots
- 36 guard
Data rate (single stream single channel) - 26.67 Mbps
Max data rate (4 streams, 4 channels) - 26.67 * 4 * 4 = 426.7 Mbps