Workshop: Coexistence challenges of LTE deployment the readiness of equipment standards and related issues

Transcription

1 Workshop: Coexistence challenges of LTE deployment the readiness of equipment standards and related issues The R&TTE Directive (99/5) and the Standardization of radio equipment. Presenter Georges de Brito Chairman ETSI WG RM / Vice-Chairman ETSI TC-ERM Brussels, 18th October 2012

2 Introduction (1/2) World Class Standards Essential requirements of the R&TTE Directive (99/5 : Article 3) Essential requirements can be found in Articles 3.1, 3.2 and 3.3 In an endeavour to publish Standards which are practical and user friendly, it often happens that different standards cover the different essential requirements found in the Directive. EMC is explicitly quoted among those Essential Requirements (3.1) For historical reasons, basic standards and other reference documents have been developed by different organizations, in time frames and life-cycles possibly totally independent It can also be anticipated that radio standards (e.g. those supporting Art 3.2 of the R&TTE Directive, and frequency management) may have to be updated (to take into account changes in technologies and radio environment) more often than standards which are of a more general in nature. 2

3 Introduction (2/2) Scope of The R&TTE Directive (99/5) World Class Standards Annex 1 of the R&TTE Directive excludes explicitly Receive only radio equipment intended to be used solely for the reception of sound and TV broadcasting services (so, TV broadcast receivers ) from the scope of the Directive Installations and the R&TTE Directive (99/5) Installations are covered by the Directive It is to be noted that many TV sets in Europe receive their input signal through installations that can be more or less complex and would typically include small [wide band] amplifiers. Harmonized Standards (HSs) under the R&TTE Directive (99/5) Compliance with an HS provides presumption of conformity to the ES HSs appear in the Directive in recitals 26, 27, 29, 30, 31, 34, 37 and 39 Harmonized Standards defined in Art 2 h). Harmonized Standards are the topic of Art 5 3

4 The R&TTE Directive (99/5) in one image 4

5 How has radio equipment been standardized? Standards for Telecommunication (Radio) Equipment Many Standards for radio transmitters and/or receivers used for telecommunication purposes have been published by ETSI. These, so called radio standards often include the characteristics of the parameters related to RF operations, for example frequency (or frequency range), modulation type, output power, adjacent channel and intermodulation performance, receiver blocking, etc. For such equipment, ETSI has also published EMC Standards addressing both immunity and emissions ; initially, these standards were stand alone (e.g. EN ) ; at a later stage an effort of consolidation was made, leading to the EN series, where a whole range of parts address particular families of equipment. TV Broadcast receivers TV Broadcast receivers are excluded from the scope of the R&TTE Directive (see its Annex 1 and slide 3) EMC Standards for such receivers have been published by CENELEC. 5 No radio standards known for TV Broadcast receivers (so far).

6 Evolution of Radio environment and adapting to it Just as for Cognitive Radio, Spectrum Management is based on some fast learning scheme and adaptive processes. Not exactly the same case for EMC.The number of versions of some radio standards shows it clearly. The general Cognitive Radio idea was originally introduced by Joseph Mitola III in 2000

7 How might broadcast network(s) have evolved in time? TV Coverage in day 1 High towers, high powers The problem was to cover complete countries (at minimum cost?) Receiver sensitivity was complemented by antenna gain Antenna gain IMPLIES DIRECTIVITY of the antennas. Radio Broadcast Receivers in Day 1 Radio Broadcast receivers did not need that much selectivity, as there was not that much competition in the TV frequency bands (which were dedicated) and the directivity of the antennas was supportive Frequency planning was another tool allowing for TV receivers with poor selectivity. These characteristics can be compared with those of PMR where adjacent channel selectivities may have been required to be in the range of 60 or 70 dbs. 7

8 How might installations for broadcast receivers have been thought of in Day 1? Installations to support TV Coverage in day 1 In remote areas, etc the signal might have to be amplified for minimum cost one could add a small amplifier after the antenna such cheap amplifiers ( just for receivers ) had possibly minimal specifications possibly no standards to support them Installations where usually made by professionals, possibly with a limited vision of what the future could be looking like... Leaving possibly no schematics or calculations behind them. Empirically the installation reached customer satisfaction end of story. 8

9 How might broadcast receivers and networks have evolved in Day 2 Day n? Radio Broadcast Receivers in Day 2, etc. Should other networks be set up, the frequency separation would typically be sufficient, the towers might be in different positions, so possibly another antenna would be used, pointing somewhere else. To be kept in mind that high gain antennas can be very frequency selective (which can also be helpful ) A poor selectivity of TV Broadcast receivers (helped by the characteristics of the antennas) could be sufficient to support the new network(s) So, the same basic principles allowed the usage in Day 2 Day 3, etc of installations and TV Broadcast receivers with poor blocking and selective performance! 9

10 Evolution of installations from Day 2 Day n Installations from Day 1 to Day n Observations made in the field recently showed that some of the installations had a hard time to follow the evolution of the TV World in the last 30 or 40 years. As a result, some 20 or 30 years installation STILL IN USE look like patch-work where a number of circuits of different generations and technologies may be found, including amplifiers and attenuators together in the same installation. Observations in Day 1 and Day n The eco-system, with its EMC Standards for TV Broadcast receivers, seemed to be operating as expected To be noted that concepts such as the market will decide can only become a reality if the eco-system is static : how could the market make wise decisions based on future events, unknown at the time of when decisions have to be made. 10

11 What changes when LTE equipment is in operation in the neighbourhood Antennas and directivity As LTE equipment may be operating anywhere, the directivity of TV receiver antennas does not necessarily help on the contrary : separation distances may become ellipses Seen from the Installation or from the TV set Some LTE equipment may be seen as operating in the TV Band (i.e. in the TV Band defined prior to the Digital Dividend). For that installation and/or TV set to operate as expected, in the presence of LTE operation, then a good adjacent channel performance and/or blocking performance is needed. Implication on the Installation and on the TV set Therefore, both Installations and/or TV sets are now expected to operate as intended in conditions similar to that of many other radio telecommunication equipment PMR standards could, therefore become some kind of reference 11

12 What may be the implications of having LTE equipment in operation in the neighbourhood Legal Background As TV broadcast receivers had been excluded from the scope of the R&TTE Directive, a critical question is to know what will be the situation with the revision of the R&TTE equipment (on going). Case when the installation and broadcast receivers are under the R&TTE Directive as revised (in 2012) Then, it could be tempting to use for TV broadcast receivers, a framework similar to that used in situations that seem to be working with success (for the satisfaction of its users) like PMR or SRDs. Under such a framework, one could think of standards both for the installations (and their components) and for the associated TV broadcast receivers 12

13 EMC, Radio (co-existence) Standards and measurement uncertainties (1/2) EMC Immunity Immunity is a typical test in EMC : The Equipment Under Test (EUT) is operated under a specified level of stress (think of 3 V/m). The output of the test is pass/fail, depending on the fact the EUT has survived the test or not! (binary outcome). Radio MEASUREMENTS receivers : Very often in ETSI Standards, for the purpose of measurements of receiver performance, the Equipment Under Test (EUT) is operated with a reasonable wanted signal level and under an increasing level of the unwanted signal level (stress level). The level of the unwanted signal (absolute or relative to the wanted signal or to an appropriate reference) at the moment when the performance of the receiver is no longer satisfactory provides the result of the measurement (think, for example of a level of 60 db). 13

14 EMC, Radio (co-existence) Standards and measurement uncertainties (2/2) Radio MEASUREMENTS measurement uncertainty : in most ETSI Harmonized Standards the maximum acceptable uncertainty is stated. The measurement uncertainty associated with a measurement can be obtained from the analysis of the measurement set up knowing the performance of the measuring equipment used. TR (v 1.4.1) provides the basics of measurement uncertainty ; many other TRs more focused on specific aspects have also been published by ETSI. Together with TR v 1.4.1, there is a.ppt presentation. Radio MEASUREMENTS and EMC exclusion bands : Clearly, 3 V/m if far more than 60 db/µv and more than what a usual receiver can stand in its operating band. Therefore, in most ETSI EMC Harmonized Standards (see EN ), an exclusion band is stated. EMC tests are not to be performed in the frequencies of the exclusion band... (Where radio measurements are expected to be performed ) 14

15 Further considerations World Class Standards Consequence of not having a radio harmonized standard in the absence of a radio harmonized standard, TV receiver selectivity and blocking performance is a question of design (tuner type, etc ) measurement results done on Digital TV receivers available in the market, show differences between TV models of more than 30 db Short term fixes and long term solutions interference problems caused by LTE 800 equipment to legacy TV receivers could be solved by installing external filters during LTE network deployment. those buying a new TV set after the LTE network(s) has been deployed may suffer interference if the TV receiver standard does not have to comply with minimum requirements for the TV receivers. Similar situation in relation to the associated amplifiers When the associated amplifier(s) do not have sufficient blocking performance, they can hide good performance of the TV receiver itself! 15

16 Towards practical proposals Implication on the standards Therefore, there could be both EMC and radio standards for both pieces of equipment (i.e. TV equipment and the associated amplifiers, etc ) And radio (receiver) characteristics such as adjacent channel selectivity and blocking (in particular of the associated amplifiers) should be included (as it has been done, for example in PMR Harmonized Standards) 16

17 Bibliography World Class Standards Example of EMC standards EN (for TV equipment) ; EN (generic) EN (for PMR) EN (e.g. part 5 for PMR, etc for 3G equipment) Example of DVB standards EN (system aspects not harmonized) EN (EN part 2) and EN (harmonized) Example of radio standards EN and EN (PMR) Other documents ECC report 138, 148, and ITU-R Recommendation BT

18 Thank you for your attention! any questions? Georges de Brito :