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Results of the LTE@800 MHz
trial in France
On 2 April 2013, a large-scale trial of mobile telecom (LTE) services operating in the 800 MHz band began in the region of St Etienne in France. It is the largest LTE trial in the 800 MHz band operating in France and the only one which includes the participation from the three telecom operators with LTE licenses in this frequency band - SFR, Bouygues, and Orange.
A total of 70 LTE base stations have been put into operation as part of the trial. These base stations are existing ones that are already used for 2G and 3G services and no new base stations have been built. The switch on of LTE services has taken place progressively so as to test and refine the methods used to handle DTT reception problems.
One of the key reasons for the selection of St Etienne as a site for the trial has been the proximity between the 800 MHz band and the frequencies used by the DTT platform thereby increasing the risk of potential interference with DTT reception. In addition, St Etienne has both an urban as well as suburban population living in different types of housing (i.e. single unit homes, apartment buildings, etc) using various means for accessing televison services.
The trial has been overseen by the frequency regulator ANFR and includes the participation of the broadcast regulator CSA, local authorities, the telecom operator ARCEP, as well as the three leading telecom operators.
Initial trial results
Based on the initial findings, nearly 99% of DTT reception problems have been the result of antenna amplifier overload. In St Etienne, there were less than 500 interference cases confirmed from the 70 LTE base stations as of the end of August. However, because of the use of collective antennas, one interference case reported could impact several households. Nearly all cases have been resolved through the use of filters. So far, no interference has been reported at the DTT gap filler sites located near LTE base stations.
The impact to DTT households has been lower than anticipated and appears to be manageable through the installation of filters.
To help viewers that may suffer from interference problems to their DTT reception, tools were put in place to provide support.
Information was made available to viewers in the local media so that viewers were aware of the LTE trial in the 800 MHz band. In addition, information was posted in residential buildings and, in homes located near LTE base stations, brochures were placed in mailboxes. In addition, a website has been set up with information on the trial at www.recevoirlatnt.fr
Local authorities as well as antenna installers and property managers were directly informed of the trial and the potential reception issues that could arise during meetings held across the region.
A call centre was also put into operation. When viewers called to report problems, the call centre first needed to determine whether the reception problems were the result of the interference from the LTE signal. If so, a filter was installed by a professional and the cost borne by the telecom operators.
Between 2 April and 2 August, a total of 1833 calls were made to the call centre to report problems with DTT reception. Of these, 776 distinct addresses were affected. A total of 90% of these could be resolved with the installation of a filter by a professional antenna installer. The remaining 10% could not benefit from this support since the household was unable to provide sufficient information to allow for the installation of a filter.
A total of 486 cases of reception issues were directly linked to the launch of LTE services in the 800 MHz band. Of these 371 were in collective homes and 115 in individual homes. All reception issues were resolved within 9 days of which 85% of reported problems were resolved within 3 days. Each base station switched on resulted in the need to install an average of 7 filters.
Other LTE trials in 800 MHz band
Licenses to trial LTE services in the 800 MHz band were issued to SFR, Orange and Bouygues in December 2011. A first trial was carried out in the region of Laval in 2011 using the frequency channel 60. This trial was managed by the broadcast network operator TDF in conjunction with the three telecom operators and the ANFR. Other trials have since taken place in the cities of Lyon, Montpellier, Toulouse and Bordeaux. However, each of these trials involves a single telecom operator.
Following the results of the LTE pilots in the 800 MHz band, telecom operators have begun to roll out their services across the country. As of 1 September, 285 base stations with LTE services have been put into operation. According to the ANFR, it has issued 1805 authorizations for the operation of LTE services in the 800 MHz band as of 1 October. However, the rollout of LTE services in the 800 MHz band has only begun and it is still too early to determine the full impact on the DTT platform.
The allocation of the 700 MHz band for the provision of mobile telecom services has also been addressed in France. Last June, the Prime Minister and the Ministry of Finance confirmed the allocation of this band to telecom services despite their current usage by the DTT platform. Discussions are currently underway to determine when the 700 MHz band will be cleared of DTT services and how a potential migration to the DVB-T2 standard could take place. The provision of telecom services using the 700 Mhz band will result in many of the same interference issues to the DTT platform as those caused by services operating in the 800 MHz band. However, there is the additional risk of interference caused by mobile uplink signals.
Importance of the DTT platform
Despite the interference issues that the introduction of LTE services in frequency bands near the DTT platform may cause, the government has pushed forward with the allocation of the 800 MHz band and, eventually the 700 MHz band to telecom operators. Ironically, the DTT platform is the leading television delivery platform in France, used by more than 60% of households.
Currently, the DTT platform provides access to 33 television programme services of which 11 services are provided in high-definition using the DVB-T standard. Viewers can also access ancillary services using the HbbTV standard. A total of 6 DTT multiplexes are available to 97% of the population with a further two multiplexes in the process of nationwide rollout.
Source: Natalie Mouyal, on behalf of the DigiTAG Project Office
DigiTAG is an association of stakeholders in the digital terrestrial TV industry and has members from broadcasting, network operators, regulatory, and professional equipment and consumer electronics manufacturing organisations throughout the world. DigiTAG has recently re-launched with new Statutes and the mission of defending and promoting digital terrestrial television on a worldwide basis, and, notably, will work tirelessly to protect spectrum for broadcasting, regardless of the technical standard used on the DTT platform.
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