Japan’s National Institute of Information and Communications Technology (NICT) has successfully deployed a 3.7km link, and achieved downlink data rates of more than 40Mbps between a base station and a device, using TV White Space spectrum in London.
NICT said that an antenna deployed on a rooftop in Denmark Hill in South London established a 3.7 km “backhaul” connection to a second site near London Bridge.
A second trial, using an LTE-based system developed by NICT, provided throughput at more than 40 Mbps between a base station and a specially designed mobile terminal in central London.
The LTE-based system operated in TDD mode using one channel and in FDD mode using two separate channels, and achieved that 40 Mbps throughput (downlink) when operated in FDD mode by using 20 MHz bandwidth of three consecutive channels.
The backhaul communications system (between the two fixed points located separated by 3.7 km) achieved more than 2 Mbps throughput at maximum transmission power 36 dBm (EIRP) based on the operational parameters provided by the database.
The trial was within the framework of Ofcom’s TV White Spaces pilot, and used a database of available frequency compiled by NICT. That database has now passed the qualification tests to be included in Ofcom’s databases list.
Ofcom’s TV White Spaces Pilot provides an opportunity for stakeholders to conduct tests with their systems and to provide feedback to the development of white space communications regulation.
NICT joined Ofcom’s pilot as both device developer and database developer. Because of the intensive and dynamic use of the spectrum in a large city such as London, the database must use the most up to date information on broadcasters’ spectrum use to calculate operational parameters for the devices in real-time. That means the devices regularly communicate with the database to exchange information on locations, occupied channels, transmission power and transmission.
NICT said in a press release:
“It should be noted that in central London there is a very high power TV tower nearby. There are also many PMSE (Programme Making and Special Events) users who operate at different locations, channels and schedules. It was a big challenge for us to operate the TV white space communications systems in such environment by looking for suitable channels and suitable transmission power.
“The trials reminded us about the unique characteristics of spectrum usage in the TV bands in large and crowded cities, and clarified the performance requirements to TV white space communications systems operating in this environment. It is expected that the experiences and the results obtained from the trials will contribute to the R&D of TV white space communications systems, and to the development of regulations regarding TV white space communications.”
NCIT’s TV White Space database holds values for antenna location, antenna height, device type and device class etc. Based on these values the database calculates maximum transmission power in each channel and the validity time then provides these operational parameters to the devices. The database has to update within a specified time after receiving power adjustment requests or scheduled/unscheduled updates of PMSE information. This means the maximum transmission power in each channel varies from time to time and channel availability can change after a short time. NCIT said this functionality was also verified during the London trials.
