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INTERNATIONAL TELECOMMUNICATION UNION

By Patricia Wagner,2014-03-26 18:35
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is not affected by the new liberalized legal framework for the operation of these networks. These techniques introduce a new family of EMC issues.

    List of Questions to be studied by ITU-T Study Group 5

    during the 2001 2004 Study Period

    Question Question title Status number

    1/5 Resistibility, EMC and safety aspects of unbundling and New

    interoperability in telecommunications networks

    2/5 EMC related to broadband access systems Continuation of Q.11/5

    and part of Q.7/5 3/5 Radio-frequency environmental characterization and Continuation of Q.10/5

    health effects related to mobile equipment and radio

    systems

    4/5 Resistibility of new types of communication equipment New

    and access networks

    5/5 Lightning protection of fixed, mobile and wireless Continuation of Q.3/5

    systems

    6/5 Bonding configurations and earthing of Continuation of Q.4/5

    telecommunication systems in the global environment

    7/5 EMC prediction through mathematical modelling New 8/5 Quality processes using electromagnetic compatibility New 9/5 Interference produced by power lines and electrified Continuation of Q.12/5

    railway lines into telecommunications networks

    10/5 Methodology for solving electromagnetic problems in New

    telecommunications installations

    11/5 Maintenance and enhancement of existing Continuation of Q.5/5

    recommendations related to human safety in the

    telecommunications environment

    12/5 Maintenance and enhancement of existing EMC Continuation of Qs.6, 8,

    recommendations 9/5 and part of Q.7/5 13/5 Maintenance and enhancement of existing resistibility Continuation of Qs.1 and

    recommendations 2/5 14/5 Terminology New

    - 2 -

    2 Wording of questions

    2.1 Question 1/5 - Resistibility, EMC and safety aspects related to unbundling and

    interoperability in telecommunications networks

     New question

    Type of question

    Task-oriented.

    Reason for question

    With the ever-increasing liberalization in telecommunications networks, unbundling and interoperability grow ever more important. This area needs some technical study so that the telecommunications industry has the ability to ensure that requirements for EMC and safety can be met in an appropriate way with new interfaces between licensed operators.

    Text of question

    This question will study the impact of the liberalization of telecommunication services on the EMC, safety and resistibility of these networks. The question will describe how to ensure that the network telecommunication protection and performance is not affected by the new liberalized legal framework for the operation of these networks. Unbalance and crosstalk are essential factors to be studied in this question.

    Specific objective and time-frame

    One or more recommendations specifying the steps necessary to ensure safe and problem-free operation in the multiple licensed operator environments shall be produced within the study period.

    Relationship to other

     Recommendations

     K-series Questions

     5, 9, 10, 12 and 13/5 Study Groups

     Groups dealing with unbundling

     Standardization bodies

     ETSI 2.2 Question 2/5 - EMC related to broadband access networks

     Enlarged continuation of Question 11/5 and part of Question 7/5 studied in 1997-2000 Type of question

    Task-oriented

    Reason for question

    The growth in demand for data services in small businesses and the home is driving telecommunications operators to provide high bandwidth connections to these customers. Because of the desire to reuse existing access systems and hardware (on cost grounds) new technical approaches generally involving spread spectrum techniques are being developed and implemented. These techniques introduce a new family of EMC issues.

    - 3 -

    Text of question

    This question will study the impact of spread spectrum techniques and other modulation techniques on the electromagnetic environment. This question will produce one or more recommendations which will allow telecommunication network operators to minimize the risk of interference to the user of the radio spectrum from these new access systems. In particular the question will study whether the increase in the probability of the existence of interfering signals generated by the spread spectrum nature of these systems is balanced by the reduction in the signal level at any specific frequency. Work will also review whether the dominant mechanisms of interference remain the same for these new systems. Topics such as dithered clocks and frequency may also be covered by this work.

    As a second stream under the same question the validity of current immunity techniques (especially the need for broadband radiated and conducted tests) for these new systems will also be studied. Specific objective and time-frame

    One or more recommendations detailing appropriate EMC requirements for broadband access systems (including the consideration of the need for a separate broadband test method and emission level) shall be produced within the study period.

    Relationship to other

     Recommendations

     K-series Standardization bodies

     CISPR, IEC, ETSI, ANSI 2.3 Question 3/5 - Radio-frequency environmental characterization and health effects

    related to mobile equipment and radio systems

     Continuation of Question 10/5 studied in 1997-2000

    Type of question

    Task-oriented

    Reason for question

    The growth of mobile and radio systems has increased the attention of the public on the level of the electromagnetic fields in the environment. This growth is driving telecommunication operators to control, to measure and to calculate the electromagnetic field radiated into the environment by telecommunication systems and radio terminals in order to comply with the electromagnetic field limits proposed by international bodies (such as the International Conference on Non-Ionizing Radiation Protection, ICNIRP) or national authorities.

    Text of question

    The purpose of this question is to study measuring techniques, procedures and calculation techniques for evaluating the electromagnetic field due to telecommunication systems and radio terminals.

    - 4 -

    The study will review the use of:

     broadband probe for site measurements: accuracy uncertainty, influence of the human body

    on the measurement results, etc.; use of different antennas: broadband antennas, dipoles, etc.;

     approximation associated to various algorithms for validity of electromagnetic field

    predictions. Specific objective and time-frame

    One or more recommendations, revision of Recommendation K.52, containing the measuring techniques and procedures for evaluating the electromagnetic field due to telecommunication plants and radio terminals with regard to possible working practices against human exposure.

    Relationship to other

     Recommendations

     K-series Standardization bodies

     World Health Organization, ICNIRP, IEEE, CENELEC

    2.4 Question 4/5 - Resistibility of new types of communication equipment and access

    networks

     New question

    Type of question

    Task-oriented

    Reason for question

    New types of equipment (examples are routers, set-top units and cable modems) are appearing in the network. Also, different types of equipment are being interconnected at a customers' premises and the requirements for the internal interfaces and the effects of these interconnections need to be considered. As an example GDTs are specified in K.12 but there is no recommendation for GDT holders. The holder is as important as the GDT and its requirements need to be specified. Text of question

    The objective of this question is to produce new resistibility recommendations for telecommunication equipment interfaces such as switching equipment, transmission equipment, repeaters, regenerators and routers, etc. and for protection systems and components such as SPDs and protection frames. The equipment may be located in telecommunication centres, customer premise buildings and outdoor enclosures. The sources of overvoltages and overcurrents that may cause damage to this equipment include lightning, power induction and mains power contacts. The types of interfaces include symmetric pair, coaxial, dedicated power feeds and mains power ports. The following issues should be particularly studied:

    a) study the resistibility requirements for STUs and cable modems and write a

    recommendation; b) study the requirements for internal interfaces in customer premises and write a

    recommendation. Consider incorporating the requirements of K.22;

    c) study the requirements for protection holders/MDFs and write a recommendation.

    - 5 -

    Specific objective and time-frame

    The outcome of these studies should be new recommendations for protection holders/MDFs, set-top units and customer premise internal interfaces within the study period.

    Relationship to other

     Recommendations

     K-series Questions

     1, 2, 6, 9, 12 and 13/5 Study Groups

     Not known at this stage Standardization bodies

     IEC and ETSI 2.5 Question 5/5 - Lightning protection of fixed, mobile and wireless systems

     Continuation of Question 3/5 studied in 1997-2000

    Type of question

    Task-oriented

    Reason for question

    In recent years, modern society has experienced a high and steady growing dependency on telecommunications. In this context, the reliability of telecommunication services has become an issue of high priority. Operators all over the world are driving their efforts in order to assure the reliability of the entire telecommunication system, comprising the key stations of the network backbone (such as the gateways and synchronism stations) up to the access network. Therefore, the protection against the dangerous effects produced by lightning discharges (high currents and associated strong electromagnetic fields) is a matter of prime concern. This question aims to establish cost-effective engineering procedures in order to allow the telecommunication operators to achieve the desired reliability in their networks.

    Text of question

    The purpose of this question is to produce new recommendations and to revise the existing ones regarding the protection of fixed, mobile and wireless telecommunications systems against the dangerous effects of lightning discharges. The study should include protection against lightning effects on:

    a) fixed telecommunication lines, including the lines made of metallic symmetric conductors,

    coaxial cables and non-metal-free fibre-optic cables; b) mobile and wireless telecommunication systems, in particular the radio base stations which

    very often have their antennas installed in high structures exposed to lightning discharges;

    c) telecommunication stations that make part of the network's backbone and, therefore, require

    a high reliability from the protection point of view.

    - 6 -

    Specific objective and time-frame

    The outcome of this question, within the study period, should result in:

    a) updated Recommendation K.25;

    b) updated Recommendation K.40, including protection against all dangerous effects that

    lightning can cause in telecommunication stations;

    c) updated Recommendation K.46;

    d) updated Recommendation K.47;

    e) a new recommendation on protection against lightning effects on lines made of coaxial

    cables;

    f) a new Recommendation on the protection against lightning effects on radio base stations of

    mobile and wireless telecommunication systems. NOTE - The revision and the editing of additional chapters of the Handbook "Protection of telecommunication lines and equipment against lightning discharges" may be accomplished. Relationship to other

     Recommendations

     K-series Questions

     6, 10, 12 and 13/5 Study Groups

     Not known at this stage. Standardization bodies

     IEC TC 81, CENELEC TC 81X 2.6 Question 6/5 - Bonding configurations and earthing of telecommunication systems in

    the global environment

     Continuation of Question 4/5 studied in 1997-2000

    Type of question

    Task-oriented

    Reason for question

    In recent years, modern society has experienced a high and steady growth of dependency on telecommunications. In this context, the reliability of telecommunication services has become an issue of high priority. Bonding and earthing of electronic equipment inside telecommunications buildings and subscriber premises is one way to achieve this reliability.

    Furthermore, the evolution of the power architecture of present and future Telecom and Datacom systems leads to the need to study the impact of the new power architecture, operated by direct voltage current (DC) or rectified current sources, on the bonding and earthing of the equipment. Text of question

    The purpose of this question is to produce new recommendations and to revise the existing ones regarding the bonding configurations and earthing of electronic equipment inside telecommunication buildings and subscriber premises as well as remote electronic sites.

    - 7 -

    The study of this question should include:

    a) implementation methods of bonding configurations and earthing to new and existing

    buildings;

    b) measuring techniques and evaluation methods of EMC performance of each bonding

    configuration; c) maintenance methods of bonding configurations and earthing;

    d) damages and malfunctions caused by lightning and conducted disturbances in imperfect

    bonding and earthing conditions (e.g. TN-S, TT, IT power system);

    e) measuring method of earthing resistance;

    f) effectiveness of earthing electrode treated with salts or colloids;

    g) method of calculation for long-rod electrodes;

    h) experience obtained with concrete-covered electrodes;

    i) earth electrodes for submarine cable telecommunication systems that use the ground as a

    conductor for remote feeding of line repeaters. Specific objective and time-frame

    The outcome of these studies should be:

    a) updated Recommendations K.27, K.31 and K.35 with better linkage and coordination

    between these recommendations and other recommendations within the K-series within the

    study period; b) a new Handbook "Earthing of telecommunication installations".

    Relationship to other

     Recommendations

     K-series Questions

     4, 5 and 13/5 Study Groups

     Not known at this stage Standardization bodies

     ETSI and IEC 2.7 Question 7/5 - EMC prediction through mathematical modelling

     New question

    Type of question

    Task-oriented

    Reason for question

    The telecommunications industry normally fulfils its EMC requirements by a combination of modular and in situ testing. This has the tendency to be expensive, have high experimental

    uncertainty (i.e. limited confidence in the results) and leave the operator with little option where

    - 8 -

    in situ testing produces adverse results. This question seeks to offer a mathematically based

    technique for minimizing the cost and maximizing the confidence of EMC compliance at the system level.

    Text of question

    This question will study mathematical techniques for assessing the EMC compliance of large systems. The question will review the suitability of techniques such as:

     probabilistic analysis,

     stochastic evaluation, and

     Monte Carlo simulation

    for inclusion in mathematical models for telecommunications EMC.

    The study will also review the use and limitations of:

     test site measurements,

     near field measurements, and

     predictions (e.g. from PCB analysis)

    as input data to the models produced.

    Specific objective and time-frame

    One or more recommendations providing guidance on whether and how mathematical techniques can be used to show EMC compliance of telecommunication systems will be produced. The recommendation may also include detail on specific models, which can be shown to have validity, and on the limitations (e.g. prediction uncertainty) of these models.

    Relationship to other

     Recommendations

     K-series Questions

     10, 12 and 13/5 Standardization bodies

     CISPR, IEC, ETSI, ANSI 2.8 Question 8/5 - Quality processes using electromagnetic compatibility

     New question

    Type of question

    Task-oriented

    Reason for question

    The telecommunications industry normally fulfils its EMC requirements and normally declares the conformity to these requirements. Moreover some EMC requirements could be an effective tool for checking telecommunication equipment quality. This question seeks to define an appropriate quality process using electromagnetic compatibility.

    - 9 -

    Text of question

    This question will study appropriate quality processes for telecommunication equipment and/or systems relating to its EMC performances.

    The question will review the suitability of techniques such as:

     quality processes and probabilistic analysis,

     selection of EMC tests, and

     EMC test procedures.

    The study will also consider the use of:

     requirements related to selected EMC measurements,

     quality indices, and

     cost analysis

    as input/output data to the defined processes.

    Specific objective and time-frame

    One or more recommendations providing guidance on whether and how these processes can be used to evaluate telecommunication apparatus/systems relating to its EMC performances. The recommendation may also include detail on specific quality indices, which can be shown to have validity, and on the limitations of these processes.

    Relationship to other

     Recommendations

     K-series Questions

     10, 11, 12 and 13/5 2.9 Question 9/5 - Interference produced by power lines and electrified railway lines into

    telecommunication networks

     Continuation of Question 12/5 studied in 1997-2000

    Type of question

    Task-oriented

    Reason for question

    The electromagnetic interference between telecommunications lines and power and electrified railway lines have been studied by ITU and the results of these studies are reported in the nine volumes of the Directives and in Recommendations K.33, K.53 and K.54. There is a need to maintain these documents and to ensure good coordination between them.

    Text of question

    This question will revise Volume VI of the Directives considering Recommendations K.33 and K.53.

    The question will also review the suitability of techniques for testing the immunity of telecommunication equipment against induced voltages by a.c. power and electrified railway lines (revision of Recommendation K.54)

    - 10 -

    Specific objective and time-frame

    A new edition of Volume VI of the Directives providing guidance on limits concerning permissible levels of induced voltages and currents and on responsibility of different network (telecommunications and power/railway) operators (2002).

    A revision of the recommendation on immunity test methods and procedures of telecommunication equipment (2004).

    NOTE - The revision of the Directives should be done in collaboration with CIGRE and UIC. Relationship to other

     Recommendations

     K-series Questions

     11, 12 and 13/5 International bodies

     CIGRE, UIC 2.10 Question 10/5 - Methodology for solving electromagnetic problems in

    telecommunications installations

     New question

    Type of question

    Task-oriented

    Reason for question

    Telecommunications equipment and systems fulfil emission, immunity and resistibility requirements requested by K-series Recommendations and are normally installed on plants and connected to networks following installation practices suggested by the K-series. The objective of these K-series Recommendations is to reduce the risk of damages and malfunctions to telecommunication systems below a tolerable level. However damages and disturbances cannot be avoided, as confirmed by field experience. This question seeks to define an appropriate approach to solve emission, immunity and resistibility problems, i.e. electromagnetic problems in telecommunication installations.

    Text of question

    This question will provide the route for solving electromagnetic problems in telecommunication installations emerging during the field service, even when the telecommunication equipment or system complies with the requested electromagnetic requirements and is properly installed. The question will collect and categorize the problems already faced by the network operator, will describe how they have been solved and will study new problems coming from the field. This question will also study possible techniques to be used in order to minimize the risk of damages and disturbances.

    The results of the collected information and studies could ultimately provide guidance to amend existing specifications, to issue new specifications and on how to build an expert system to minimize and solve electromagnetic problems which could appear in telecommunication installations during their service and could be an input for new EMC and resistibility recommendations or for amending existing ones.

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