In: Press releases, Services 16 Sep 2014 Tags: , , , , , ,

From Land mobile

Brazil is planning to reuse its digital dividend 700 MHz frequencies for new 4G mobile services alongside planned digital television services. Overseen by ATDI, the company reports on the mitigation of potential interference issues

It’s the country with more World Cup successes than anywhere else but few spectrum resources.

So when Brazil began the process of making digital dividend frequencies available, mobile phone companies were first in the queue to lay claim to them. But television broadcasters, sensitive to the needs of providing both digital and analogue services across the vast country, resisted giving new allocations to mobile operators.

The phone companies, therefore, needed to demonstrate to spectrum regulator Anatel (Brazil’s national communications agency) that their proposed new services could coexist with existing TV transmissions. To do this, they – as represented by the GSM Association (GSMA) – approached UK-based planning and modelling company ATDI to complete a coexistence study.

ATDI lead engineer Paul Grant oversaw the project. He comments: “It was an interesting challenge because of the size of the country and the importance of terrestrial TV broadcasting. So any mobile broadband services introduced following a digital dividend must be able to coexist with television services.”

The newly liberated frequencies the GSMA members were hoping to use for their new LTE services were between 703 and 803 MHz.

Both analogue and digital television had to be considered, as there was to be a phased switch-off of the analogue signal.

Measurement data exists for ISDB-T (Integrated Services Digital Broadcasting) and IMT (International Mobile Telecommunications) systems and this, according to Grant, was useful for establishing coexistence rules. He adds: “It was also useful to determine the impact of interference, which is what ATDI’s study endeavoured to do. This was achieved by modelling the likely interference situation for sample areas and equating this in terms of a denial of service to a population.”

The modelling used a planning approach with figures based on ITU sources and data from Anatel. ATDI has successfully used this modelling approach in other countries to inform similar debates and the decision-making process.

In Brazil, the modelling used a number of scenarios to explore the potential interference between the broadcast and cellular services. Three study areas were used: São Paulo, Brasilia and Campinas. They were chosen as they are likely to be some of the most constrained areas and the potential problems were deemed to be less acute in other areas and so easier to mitigate.

Although the original dividend date was planned for 2016 there will be a staggered switch off between 2015 and 2018; the analogue transmitters continuing to operate will serve more rural population areas.

The modelling scenarios considered are:

LTE base station (BS) interferes with ISDB-T fixed rooftop receivers
LTE user equipment (UE) interferes with ISDB-T fixed rooftop receivers ISDB-T interferes with LTE UE
ISDB-T interferes with LTE BS
LTE BS interferes with analogue TV
LTE UE interferes with analogue TV
Analogue TV interferes with LTE BS
Analogue TV interferes with LTE UE

For each scenario the analysis considered two interference mechanisms; out of band interference and blocking interference.

The probability of interference has been categorised into either: high, medium, or low.

The number of people who experience interference is relatively low, with typically less than 50,000 for São Paulo and less than 10,000 for Brasilia and Campinas for out of band interference. With mitigation applied those numbers could be virtually eliminated.

For ISDB-T into LTE base station the separation distances required can be reduced from more than 10 km to less than 600 metres following mitigation.

For LTE base station into analogue TV the separation distance required is typically a few kilometres. For the uplink the separation distance required is generally less than 100 metres.

For analogue TV into LTE base station the separation distance required is greater than 10 km but reduces to below 10 km with mitigation. For the LTE mobile the separation distance required is of the order of 10 km.

Mitigation
A number of mitigation techniques were considered by ATDI to alleviate the potential interference issues:

Limit emission power in top TV broadcast channels
LTE filtering
Broadcast filtering
Use of orthogonal polarisation
Domestic TV receiver filtering
Improved domestic antenna
Good quality TV receivers

Of these options applying filters to the LTE and ISDB-T transmitters and limiting the emission power in the top TV broadcast channels were deemed to be the most beneficial by ATDI. But Grant notes: “Applying filters is likely to be the most costly option but does reduce the probability of interference.”

The probability of interference from analogue TV into LTE was classed as medium. Filtering on the analogue transmitters, which would reduce the out of band emissions, was not considered as the analogue transmitters are scheduled for switch off within the next few years and so wouldn’t have been a cost effective solution. A combination of frequency and geographic separation would be required to find an acceptable solution during the transition period from analogue to digital.

“The use of orthogonal polarisation was not considered viable due to the complexity and cost involved,” comments Grant. “The options for the domestic TV receiver should be used on a case by case basis where local interference issues are experienced.”

“This was a great project to be involved in as Brazil is one of the world’s fastest-growing economies,” he adds. “This work is helping the country to adopt world-class mobile data and voice communication systems while ensuring that TV services are not adversely affected.”

In: Resources 29 Aug 2014 Tags: , , , ,

Definitions:

Mechanical Tilt
● The downtilt angle varies over the horizontal beamwidth. Patterns
measured ±90° from the center of the beam have decreasing
tilt angle until there is no tilt 90° from the main beam.
● The horizontal half-power beam width increases with greater
downtilt angle.
● The resulting gain reduction depends on azimuth direction.

TiltM

Electrical Tilt
● There is uniform downtilt over the whole azimuth range.
● The horizontal half-power beamwidth is independent of the
downtilt angle.
● There is identical gain reduction in all azimuth directions.

TiltE

 

TiltEM

In: Products 07 Jul 2014 Tags: , , , , , , , , , ,

WSDonline4

What are the TV white-spaces?

TV White Spaces (TVWS) are vacant frequencies made available for unlicensed use at locations where spectrum is not being used by licensed services. This band is currently used by Digital Terrestrial Television (DTT) and Program Making and Special Events (PMSE) users.

WSD

“White Space technology will work in a similar way to Wi-Fi, which uses a wireless router to send and receive information to other wireless devices. The main difference is that the White Space router – or “master” device as it is known technically – will first need to consult a list of databases hosted online. It will notify one of these databases of its location and update it on a regular basis. The database will then return details of the radio-frequencies and power levels it is allowed to use. This will ensure that the devices do not interfere with existing licensed users of the spectrum, which include Digital Terrestrial Television and wireless microphone users.”

Applications:

Enhanced Wi-Fi: The majority of current Wi-Fi devices operate in spectrum at 2.4GHz. White Spaces could provide new capacity, while boosting the range of devices, potentially enabling Wi-Fi networks that stretch across towns and cities. This is thanks to the lower frequency of TV White Spaces (typically between 470 and 790MHz).

Rural broadband: White Spaces could be used to provide rural locations with broadband services. In practice, this could be achieved by building a network of transmitters that use White Spaces to link remote houses and villages to larger towns that are already connected to the internet. Trials are currently being undertaken by industry to test this on the island of Bute, Scotland.

Machine-to-Machine Communications (M2M): A relatively new area of innovation called Machine-to-Machine Communications allows information to be exchanged between devices. Many experts believe that in the coming years billions of devices will be able to connect wirelessly and via the internet for a range of applications. White spaces could be used to wirelessly transmit this information, using its additional range to reach deep inside buildings. This could be especially useful for wirelessly measuring utility meters in consumers’ homes – just one of a wide number of potential applications. Other examples include using White Spaces to keep an inventory of stock owned by a business, or making it easier for scientists to conduct research by automating the measurement of different readings.

WSDspectrum

The UHF TV band (470-790 MHz) and its users

 

ATDI announces new White-space features in ICS suite.

Since 1997, ATDI supports White-Spaces in ICS telecom (3.5 GHz band, Teledesic and Skybridge projects…). Now, ICS suite allows you to process the complete workflow and publish the data Online.

WSDTVWScalc

TVWS calculations and Management with ATDI tools

Calculation method and WSD management (pdf)

 

 

ICS suite white-space features:

. DTT coverage
. Reserved channels
. Allotments, Assignments, PSME, International coordination, Protected areas (polygons)
. DTT white-space calculation
. TVWS availability calculation
. Available Spectrum maps
. WSD channel assignment
. WSD to DTT interference calculation
. Data storage:
. Location
. Channel
. WSD class
. Permitted power level
. Online access
White-spaces are managed both locally and in the Cloud thanks to ICS Manager

WSDcalc

 

Backoffice:

. DTT protected area calculation

. WSD availability map calculation

. Interference WSDs vs WSDs and WSDs vs DTT

. Import TVWSD availability maps and tiling

. Web service validations

. WSD checking

. Statistics

. Status of data in the Cloud

Cloud service:

. Map tiles (WMTS server)

. Web services to communicate with WSD (location, QoS, Traffic)

. Import WSDs from Cloud (scenarios)

WSDonlineCH


White space map calculation (multi-technologies):

. Devices or Routers vs Licensed service areas (C/I mode)
. Licensed services vs Devices or Routers (IRF and C/I modes)
. Licensed services vs earth Satellite Rx (GSO, NGSO, Constellations)
. Devices vs Devices or Routers vs Routers or Devices vs Routers (IRF mode)
. Devices or Routers vs Polygons or Routes (PFD)

From UKPM files (from 0.01 m to 100 m resolution)

. LTE vs DTT
. WSD vs DTT
. Multiple log-normal signal calculator (Schwartz & Yeh / Fenton-Wilkinson)
. UKPM household automatic update
. Up to 100 000 interferers (base stations) by DTT channel
. Up to 2 000 000 interferers (WSDs) by DTT channels

WSD vs DTT features:

. Large choice of propagation models (outdoor, indoor, mixed outdoor/indoor, Full 3D)
. Multiple resolution maps (from 0.01 m to 1000 m)
. White-space devices: Class 1, 2, 3, 4, 5
. Rejection: ETSI EN 301 598 or user defined
. Household distribution and filter
. WSD distribution
. ATPC
. Bandwidth ratio
. User defined C/I required and NFD matrices
. DTT white-space maps
. TVWS availability maps (C/I, permitted power levels)
. WSD interference (WSDs vs DTT receivers and DTT transmitters vs WSDs)
. Spurious emissions
. Interference analysis: Multiple scenarios
. Rx antenna discrimination (ITU-R 419, OET69, User defined) (DTT receivers)
. Automatic DTT selection (up to N+- 15)
. Foreign DTT transmitters are taken into account (BRIFIC online access)
. Offline and Online Worldwide database (Location, Channels, Power levels, WSD classes)
. WSD location by coordinates or addresses
. Export WMAS (Google map, Bing Map, OSM), EPSG:4326…
. Web services

Export data formats:
. Matrices (form 0.01 m to 1000 m resolution)
. XML
. SQL
. SHP
. WKT
. Google Earth
. Cloud SQL Azure

Queries:
- For a given location (address, coordinates, click on map…)
. List of available channels and max power level by channel
- Coverage maps per channel
- Protected maps per channel
- Tx per channels

Cloud Map Storage (Windows Azure):
- For each point:
. List of available channel(s)
- For each channel
. Max power level by WSD class

WSDpplatform

Platform overview for WSD management

 

Diapositive2

Diapositive3

Diapositive4

Diapositive5

 

wsdICSonline

wsdreport

ICS suite:

ICS telecom

ICS manager (+ SQL server)

ICS online (Windows Azure platform)

 

Map comparison (Spectrum bridge vs ATDI)

DTT protected area:
SpectrumBridge

Spectrum Bridge map (Channel 32 Singapore)

Map comparison (Google vs ATDI)

GoogleWSD

Google Spectrum TVWS availability map (USA)

 

DTTWSmap

ATDI protected area map (Channel 28 Oman – WSD 0.22 W EIRP – 100 m resolution)

 

White-Space calculation example: Oman Channel 39:

WSD maps (Channel 39 – Oman – 100 143 225 WSD locations from 13 to 23 dBm and from Class 1 to 5  – 3 602 600 DTT receivers - map resolution: 100 m

Scenario: WSD 0.22 W max outdoor, Dynamic 10 dB (from 23 dBm to 13 dBm), Classes 1 to 5, DTT map: all servers, Rejection up to N +/-3 .

OMAN_DTT

DTT map (all channels)

Oman_ProtectedAreaC39

Channel 39 – Protected area (servers)

 

Oman_CImapC39D

WSD availability map (channel 39) – ITU-R 452:

Blue area = exclusion zone

Green areas = restricted zones (plus Power level constraints)

Brown area = OK

 

OmanCx

Available Spectrum Map

 WSDquery

Query

ICSoDevices

WSDonline2

Process:

DTT protected area maps and WSD availability maps are calculated in ICS telecom.

The WSDB is managed by ICS manager and accessible via Web service.

ICS manager hosts the TVWS availability tile maps (WMTS) and perform real-time checking.

WSD interference are performed every time a new WSD is ON (power sum, log-normal sum).

Start and End “switch ON” periods are managed by the system.

ICS online allows you to display DTT protected area maps, TVWS availability maps, WSD locations (including channels and power levels + info), provides a form to enter new WSD (technical parameters, Class, location…).

DTT maps for all countries using BRIFIC or more accurate data if available (or both: i.e. Brific for borders and operator/regulator data for the target country)…

BRIFIC is accessible online thanks to ICS online and is updated twice a month.

WSD application form

WSDs transactions (IN/OUT): Location, QoS, Traffic, Power levels, Channels…

WSDs storage

 

 

Brochure

Brochure (pdf)

ATDI Presentation – TV White Space Calculation and Database

WhiteSpaces: newsletter

 

Related ICS telecom functions:
. LTE vs DTT (UKPM and P2MP methods)
. Coordination with aeronautical radionavigation radar in the 2.7 GHz band