TVWS: Leveraging unused TV broadcasting spectrum for two way communications. Ermanno Pietrosemoli

Transcription

1 TVWS: Leveraging unused TV broadcasting spectrum for two way communications Ermanno Pietrosemoli

2 Agenda Spectrum Allocation What are T V White Spaces TVWS Standards T/ICT4D model Deployment in Malawi Deployment in Mozambique 2

3 Evolution of Spectrum allocation Fixed allocation 1) Government assigned 2) Auction 3) Beauty Contest Dynamic Spectrum allocation Best, but regulatory and technology hurdles must be overcome 3

4 Spectrum Availability Assessment Two methods to determine availability: a) Spectrum sensing b) Geo-location Database The two methods have drawbacks, but both the FCC and Ofcom favor the database approach at this time. Cognitive radios can implement both. 4

5 Analog Television White Spaces 5

6 White Spaces Need for more spectrum to satisfy the growing demand. Plenty of spectrum allocated to TV broadcasting is currently idle, specially in rural areas of developing countries. Spectrum re-farming: opportunistic spectrum usage. Many standard efforts and pilots with temporary spectrum access permits. Regulations in place in US, UK, Finland and Singapore. 6

7 Television White Spaces: definition a) The spectrum that has been assigned to TV broadcasting but it is not currently being used. This applies particularly to developing countries, in which there has been no economic incentive for broadcaster to use every available TV channel. b) The spectrum that must be left free in between two analogous TV channels to prevent interference. c) The spectrum that has been reclaimed as a consequence of the transition to digital terrestrial TV, which is more spectrum efficient. See: On the relevance of using affordable tools for white spaces identification at 7

8 TV Band Devices Standards IEEE for long range transmission Wireless Regional Area Networks (WRAN) IEEE af for short range, OFDM PHYs with 5, 10 and 20 MHz channel widths IEEE m for device control and command applications IEEE for coexistence among multiple TV white space networks IEEE DySPAN aimed at Dynamic Spectrum Access Networks IEEE h originally meant for the MHz contention band but now also specified for the TV bands ECMA 392 directed at personal and portable wireless devices, Weightless mainly focused at Machine-to-Machine interactions IETF PAWS covering the specification of the mechanism for discovering a white spaces database and method for its access. 8

9 Propagation advantages of TV bands The superior propagation features of the lower frequencies is due to three factors: a) Lower free space loss b) Better diffraction efficiency c) Lower building attenuation 9

10 Updated January

11 T/ICT4D model Training Research Deployment 11

12 Spectrum in Nairobi 12

13 13

14 Percentage of measurements below -85 dbm 14

15 209 reports RfTrack spectrum monitoring measurements and visualization 15

16 Pilot TVWS installations Malawi 2014 Mozambique

17 Malawi 17!X

18 St.Mary School (2.4 km) AirWing (7 km) Seismology Dpt (1 km) Pirimiti Hostpital (19 km) 18

19 Omnidirectional 6 dbi Base Station antenna for TVWS in Malawi 19

20 11 dbi client antenna for TVWS in Malawi 20

21 TVWS CPE in Malawi 21

22 22

23 TVWS Network in Maputo, Mozambique 15 km 23

24 Base Station with Sectorial 11 dbi Antenna at ISTEG Mozambique September

25 Measuring TVWS received signal 25

26 Conclusions TVWS offer an opportunity to provide Internet access in rural areas of developing countries. Regulator approval is the main requirement, since hardware is already available and newer manufacturers are coming up. Developing countries could leapfrog in deployment, since fewer TV channels are currently exploited there. Future is in dynamic spectrum access.!x 26