What is TVWS?
1What is TV Whitespace communications?
It is a bi-directional wireless data communications standard that uses the vacant/unused spectrum (50 – 862 MHz) between broadcast TV bands. It is most suitable for providing last mile/hop wireless network connectivity.
2Which countries have regulations in place and have deployed TVWS communications?
USA, UK, Singapore and most African Countries
3Is TVWS suitable for mobile broadband?
TVWS is most suitable for fixed wireless broadband due to the CPE antenna size.
1How much spectrum is available for TVWS communications?
Availability of free spectrum is dependent on the region in which you are operating. For example in the city of London over 200 MHz in UHF band is available for TVWS communications (Source: Ofcom, 2015).
2What is the status of TVWS communications in India?
TRAI (regulator in India) has proposed the use of 470-585 MHz (115 MHz) for TVWS communications. Entire band is expected to be available for TVWS communications.
3My area is in a tropical belt with trees and heavy wind/rains during monsoons. I have tried 2.4/5.8 GHz LOS WiFi connections and my customers complained about spotty connections. How will TVWS improve?
TVWS uses UHF band and hence, the penetration and coverage through dense foliage is better than 2.4/5.8GHz ISM bands. Further, TVWS does not require line of sight connection and hence, it is easier to install and maintain.
4What is the recommended antenna for TVWS communications? At what height should the base station and CPE antennas be placed?
We recommend Yagi Antenna from Pro-cell. For good coverage, the base station antenna must be at a height of 30 meters from the ground. It is recommended that the CPE antenna be mounted on the roof top of the customer’s premises.
5What are the regulations governing license free wireless bands in India?
|Band (MHz)||STD||Bandwidth||EIRP||Ant. Height|
|2400-2483.5||ISM||Gazette||10/20 MHz||26 dBm||Indoor only|
|2400-2483.5||ISM||Gazette||10/20 MHz||36 dBm||Roof top + 5m||Outdoor|
|5150-5350||U-NII-1,2||20/40 MHz||23 dBm||Indoor only|
|5725-5875||ISM||20/40 MHz||23 dBm||Indoor only|
|5825-5875||ISM||GR38||20 MHz||36 dBm||Outdoor|
6Which are the two standards for TVWS communications?
TVWS communications protocol is specified in IEEE 802.22 and 802.11af standards. Saankhya Software defined Radio (SDR) platforms can be remote configured to work in either standards.
7As a WISP, which TVWS standard should I choose?
If your coverage area is over 2km, we recommend you go with IEEE802.22. IEEE802.11af standard is similar to WiFi standard except that it provides coverage over a longer distance (1 km) compared to traditional wifi (802.11bgn).
8What are the key features of 802.22 standards
Key features of 802.22 include
- Modulation: TDD-OFDMA (BPSK to 64QAM)
- Bandwidth: 6/7/8 MHz (can be extended to 10 MHz outside the standard)
- Max Data Rate: 30 Mbps/8 MHz
- Distance Covered: >15km Non Line of Sight (NLOS)
- Topology: supports Point to Point (P2P) and Point to Multi-Point (P2MP)
1How many subscribers can I support with one 8 MHz base station?
Assuming a data rate of 4Mbps to the end subscriber and contention ratio of 1:10, 75 households can be served by one base station.
2I need to scale up my infrastructure to support more households. How can I achieve it?
Please check the availability of unused spectrum in your region. An additional 20 more households can be supported with the existing base station (Thanks to Saankhya’s SDR architecture!) by increasing the bandwidth of the channel to 10 MHz. For supporting more than 100 households, you will need to add additional base stations (same tower if possible). Please talk to Saankhya representative for frequency planning (less interference).
3What is the infrastructure that I need to start a TVWS WISP?
- TVWS base station with Network Management Software (provisioning, billing, frequency planning, remote monitoring), Tower, Antenna and CPE from Saankhya Labs and its partners
- ONT, Router, Ethernet Switch – Cisco/Microtik or similar
- Power Supply
4What is the Capex required as a WISP to provide data services to 75 households?
Roughly, it will cost under $100/subscriber (Rs.6K) plus the CPE cost/subscriber. The cost will drop with more installations.
5How does WiFi capex compare with TVWS?
While a traditional Wi-Fi router has a relatively limited range, around 50 meters, and can be blocked by walls or other environmental barriers, TV White Space technology can cover an expanse of over 10 kilometers in diameter (200 times the distance)! Hence, to support 75 households spread over an area of 5km radius, the cost of WiFi infrastructure will be at least 100x more than that required for TVWS. Majority of the cost will be either from setting up the LOS Wireless links or from the cost of laying fiber in the neighborhood. TVWS operating in the TV band and in dynamic spectrum allocation mode is also robust compared to the crowded wifi spectrum.
6Can I get a platform for evaluation? And, how much does it cost?
TVWS platform is available now. The kit contains one base station and two CPEs. Please contact your Saankhya Labs sales representative for pricing details.
1Using a realistic 802.22 base station, antenna, what is the achievable bandwidth for 8MHz at 15km, 10km and 5 km?
The distance and throughput are a function of the bandwidth, Antenna height, cable losses and the emitted RF power. Typically with a TVWS max. emitted power of 36dbm we can achieve 30Mbps up to 10km. Beyond 10km, the throughput will drop with distance.
2Can I use TVWS as a backhaul or for extending the range?
Yes, Saankhya platform can be configured for P2P operation and used as a backhaul or as a relay to extend the network coverage.