Circular No. 28/2017/TT-BTTTT Issuing the "National Technical Regulation on Electromagnetic Compatibility for Fixed Radio Transmission Equipment and Related Auxiliary Equipment"

 

CIRCULAR

ISSUING THE NATIONAL TECHNICAL REGULATION ON ELECTROMAGNETIC COMPATIBILITY FOR FIXED RADIO LINKS AND ANCILLARY EQUIPMENT

REGARDING THE FIXED RADIO TRANSMISSION DEVICES AND ASSOCIATED EQUIPMENT

Pursuant to the Law on Standards and Technical Regulations dated June 29, 2006;

Pursuant to the Law on Telecommunications dated November 23, 2009;

WHEREAS, the Law on Radio Frequency Spectrum dated November 23, 2009;

WHEREAS, Decree No. 127/2007/NĐ-CP dated August 1, 2007 of the Government detailing and guiding the implementation of certain provisions of the Law on Technical Standards and Regulations;

Pursuant to Decree No. 17/2017/NĐ-CP dated February 17, 2017, issued by the Government, on the functions, tasks, powers, and organizational structure of the Ministry of Information and Communications;

Pursuant to the proposal of the Director of the Science and Technology Department,

The Minister of Information and Communications issues this Circular to stipulate the national technical regulation on electromagnetic compatibility for fixed radio transmission devices and associated equipment.

Article 1. Attached to this Circular is the national technical regulation on electromagnetic compatibility for fixed radio transmission devices and associated equipment (QCVN 114:2017/BTTTT).

Article 2. This Circular takes effect from July 1, 2018.

Article 3. The Heads of the Office, the Department of Science and Technology, the Heads of agencies and units under the Ministry of Information and Communications, the Directors of Provincial Departments of Information and Communications, and relevant organizations and individuals are responsible for implementing this Circular./.

 

 

QCVN 114:2017/BTTTT

NATIONAL TECHNICAL REGULATION ON ELECTROMAGNETIC COMPATIBILITY FOR FIXED RADIO LINKS AND ANCILLARY EQUIPMENT

National technical regulation on ElectroMagnetic Compatibility (EMC) for fixed radio links and ancillary equipment

Foreword

QCVN 114:2017/BTTTT is based on the European Telecommunications Standards Institute (ETSI) standard ETSI EN 301 489-4 V2.2.1 (2015-05).

QCVN 114:2017/BTTTT was compiled by the Post and Telecommunications Engineering Institute, reviewed and approved by the Department of Science and Technology, and issued together with Circular No. 28/2017/TT-BTTTT dated November 7, 2017.

 

NATIONAL TECHNICAL REGULATION ON ELECTROMAGNETIC COMPATIBILITY FOR FIXED RADIO LINKS AND ANCILLARY EQUIPMENTYes FOR FIXED RADIO TRANSMISSION DEVICES ANDẪASSOCIATED EQUIPMENTO This regulation specifies the requirements for electromagnetic compatibility (EMC) for fixed radio transmission devices and associated equipment in fixed service operations.

National technical regulation on ElectroMagnetic Compatibility (EMC) for fixed radio links and ancillary equipment

Chapter 1. GENERAL PROVISIONS

1.1. Scope of Application

Technical specifications related to the antenna ports of radio devices are not within the scope of this regulation. These specifications are defined in corresponding product standards for effective frequency spectrum utilization.

This regulation sets out the measurement conditions, evaluation criteria, and quality standards for fixed radio transmission devices and associated equipment similar to and digital point-to-point and point-to-multipoint fixed systems.

This technical regulation applies to domestic and foreign agencies, organizations, and individuals engaged in production, business, and operation of devices within the scope of this regulation on the territory of Vietnam.

1.2. Applicability

QCVN 18:2014/BTTTT, National technical regulation on electromagnetic compatibility for wireless telecommunications equipment.

1.3. Referenced Documents

ITU-R Recommendation F.746-3: "Radio-frequency channel arrangements for radio-relay systems".

ITU-R Recommendation F.1191-1: "Bandwidths and unwanted emissions of digital radio-relay systems".

ETSI EN 302 217-2-2: "Fixed Radio Systems; Characteristics and requirements for point-to-point equipment and antennas; Part 2-2: Digital systems operating in frequency bands where frequency coordination is applied; Harmonized EN covering the essential requirements of Article 3.2 of the R&TTE Directive".

ETSI EN 302 217-3: "Fixed Radio Systems; Characteristics and requirements for point-to-point equipment and antennas; Part 3: Equipment operating in frequency bands where both frequency coordinated or uncoordinated deployment might be applied; Harmonized EN covering the essential requirements of Article 3.2 of the R&TTE Directive".

ETSI EN 302 326-2: "Fixed Radio Systems; Multipoint Equipment and Antennas; Part 2: Harmonized EN covering the essential requirements of Article 3.2 of the R&TTE Directive for Digital Multipoint Radio Equipment".

ETSI EN 301 460-1: "Fixed Radio Systems; Point-to-multipoint equipment; Part 1: Point-to-multipoint digital radio systems below 1 GHz - Common parameters".

ETSI EN 301 997-1: "Transmission and Multiplexing (TM); Multipoint equipment; Radio Equipment for use in Multimedia Wireless Systems (MWS) in the frequency band 40.5 GHz to 43.5 GHz; Part 1: General requirements".

1.4.1 Base Station (BS)

1.4. Terms and Definitions

Alternative name for the Central Station (CS). 1.4.2 Central Station (CS)

The Central Station may be divided into two systems:

• Conversion system also known as the Central Control Station (CCS) - (internal interface for conversion); and • Radio system also known as the Central Radio Station (CRS) - (central center frequency band/radio transceiver)

NOTE: When deployed, the term Base Station is also used instead of Central Station. In this regulation, Base Station and Central Station can be interchanged.

1.4.3 Channel Separation (CHS)

Channel separation is equal to XS/2 with frequency interleaved channel arrangement according to ITU-R F.1191 recommendation and equal to XS with co-channel and interleaved frequency channel arrangement according to ITU-R F.746 recommendation, XS being the radio frequency spacing between the center frequencies of adjacent radio frequency channels when the polarizations are the same and in the same direction.

1.4.4 Operating Frequency Range

The range of radio frequency bands that the Equipment Under Test (EUT) operates in. 1.4.5 Repeater Station (RS)

Outdoor radio transceivers tasked with amplifying radio signals, with or without subscriber interfaces.

1.4.6 Terminal Station (TS) Outdoor radio transceivers with subscriber interfaces.

Alternating Current

AC Bit Error Rate

CCS

Central Control Station CHS

Channel Separation

1.5. Abbreviations

Chapter 2. TECHNICAL PROVISIONS

2.1. Electromagnetic Compatibility Emission

2.1.1. General Requirements

The requirements for electromagnetic compatibility emission at the ports of radio equipment and/or related ancillary equipment are specified in Table 1 of QCVN 18:2014/BTTTT.

For fixed service radio transmission equipment, only the requirements for radio equipment and fixed-use auxiliary equipment listed in Table 1 shall be applied.

2.1.2. Specific Conditions

The specific conditions specified in Table 1 below relate to EMC emission measurement requirements as stipulated in Article 2.1 of QCVN 18:2014/BTTTT and Articles 2.3 and 2.4 of this standard.

Table 1 - Specific Conditions for Emission Measurementperiod EMC

2.2. Immunity

2.2.1. General Requirements

The immunity EMC requirements on the ports of radio equipment and/or auxiliary equipment are specified in Table 4 of QCVN 18:2014/BTTTT.

For fixed service radio transmission equipment, only the sections with requirements for radio equipment and fixed-use auxiliary equipment in Table 4 of QCVN 18:2014/BTTTT shall be applied.

2.2.2. Specific Conditions

The specific conditions specified in Table 2 below relate to the testing methods and quality criteria as stipulated in Article 2.2 of QCVN 18:2014/BTTTT and Articles 2.3 and 2.5 of this standard.

Table 2 - Specific Conditions for Immunity Testingện for measuring immunity EMCn l n for measuring

2.3.1. General Provisions

For the purposes of this standard, test conditions in Appendix A of QCVN 18:2014/BTTTT may be applied when appropriate. This standard supplements additional provisions regarding test conditions for fixed radio transmission equipment and auxiliary equipment in fixed services.

2.3.1.1. Test Conditions and Configurations

This section specifies the test conditions and configurations for emission and immunity tests as follows:

• The transmitter must include at least the components between points E’ and A' as shown in Figure 1. Additionally, the transmitter may include any other components as shown in Figure 1. If these additional components are part of the transmitter or the transmission system, they must also comply with the requirements of this standard;

NOTE 1: For the purpose of determining reference points, the branch network (from point B' to point C') does not hybridize.

NOTE 2: Points B' and C' may coincide depending on the equipment configuration.

Figure 1 - Components of a Transmitter

• The receiver must include at least the components between points E and A as shown in Figure 2. Additionally, the receiver may include any other components as shown in Figure 2. If these additional components are part of the receiver or the reception system, they must also comply with the requirements of this standard;

• The transceiver must include at least the components within the range from point E' to point A' and from point A to point E as shown in Figures 1 and 2, and it may combine with any other components. If these additional components are part of the transceiver, they must also comply with the requirements of this standard;

NOTE 1: For the purpose of determining reference points, the branch network (from point B to point C) does not hybridize.

NOTE 2: Points B and C may coincide depending on the equipment configuration.

Figure 2 - Components of a Receiver

• The equipment under test must be tested under the environmental conditions declared by the manufacturer regarding humidity, temperature, and supply voltage;

• The test configuration must be as close as possible to normal usage;

• If the equipment is part of a system or can be connected to auxiliary equipment, it must be tested when connected to the minimum configuration of auxiliary equipment necessary to use the ports;

• Normally operating ports connected to auxiliary equipment or other devices must either be connected to those devices or terminated with dummy loads that simulate the input/output characteristics of the auxiliary equipment or other devices. RF input/output ports must be properly connected;

• If the equipment has a large number of ports, only enough ports must be selected to simulate actual operating conditions and ensure that all different types of terminations are tested;

• Ports that are not connected to cables during expected operation, such as service connections, programming connections, temporary connections, etc., must not be connected to any type of cable for EMC compatibility testing. At the location where cables are connected to these ports or extended for lengthening during EUT testing, preventive measures must be taken to ensure that the evaluation of the EUT is not affected by the addition or extension of these cables;

• Test conditions, test configurations, and operational modes must be recorded in the test report.

2.3.1.2. Emission Testing

Apply Article 2.1 of QCVN 18:2014/BTTTT with the following modifications.

The information connection of point-to-multipoint systems must be established, including a central station and at least one terminal station. These stations must be tested separately.

2.3.1.3. Immunity Testing

Apply Section 2.2.2 of QCVN 18:2014/BTTTT with the following modifications.

Figure 3 - Test Configuration for Transmitters

The test configuration for transmitters must be carried out according to the principle illustrated in Figure 3, and for receivers according to the principle illustrated in Figure 4, and for transceivers according to the principle illustrated in Figure 5.

Measuring instruments must be placed outside the test environment. Appropriate measures must be taken to prevent any effect of unwanted signals on the measuring instruments.

Measurement devices must be located outside the test environment. Appropriate measures shall be taken to prevent any effect of unwanted signals on the measurement devices.

When measuring immunity capability, the generator must operate at its rated output power. The generator's input must comply with the provisions set forth in 2.3.2.1 (see Figure 3). Information connection must be established at the start of measurement and maintained throughout the measurement period.

Figure 4 - Test configuration for receiversìMeasurement and testing equipment for receivers

When measuring immunity capability for receivers, the desired RF input signal of the receiver must comply with the provisions set forth in 2.3.2.3 (see Figure 4). Information connection must be established at the start of measurement and maintained throughout the measurement period.

Figure 5 - Test configuration for transceivers

In cases where transceivers cannot operate at the same frequency between the transmitter and the receiver, the desired input signal of the receiver must comply with the provisions set forth in 2.3.2.3. The transmitter must operate at its rated output power, and its input must be the output of the receiver (repeat mode) (see Figure 5).

Similar test configurations also apply when the transmitter and receiver operate at the same radio frequency.

Measurements must be conducted according to the operating modes specified herein.

Information connection must be established at the start of measurement and maintained throughout the entire measurement period.

For immunity tests of auxiliary equipment that does not separate pass/fail criteria, the receiver, transmitter, or transceiver together with auxiliary equipment must be used to evaluate whether the auxiliary equipment passes or fails.

The minimum configuration of point-to-multipoint systems must include a central station and an end station, unless more end stations are required to establish a representative test configuration.

Information connection must be established at the start of measurement and maintained during the measurement period between the central station and (the) end station(s).

These stations must be measured separately.

2.3.2. SNo. ignal test arrangement

Apply Appendix A.2 of QCVN 18:2014/BTTTT.

2.3.2.1 Signal test arrangement at the input of the transmitter

Apply Appendix A.2.1 of QCVN 18:2014/BTTTT with the following adjustments.

The transmitter's input must be connected through the corresponding input to the signal source as shown in Figures 3 and 5.

The desired signals must represent the corresponding original band input signals when the transmitter operates normally.

2.3.2.2 Signal test arrangement at the output of the transmitter

Apply Appendix A.2.2 of QCVN 18:2014/BTTTT with the following adjustments.

To establish information connection for the desired output signal, the signal must be sent from the transmitter's RF output through an appropriate attenuator via coaxial cable or waveguide. Appropriate measures must be taken to minimize the effects of unwanted currents on the outer conductors of the coaxial cable or waveguide at the time the EUT is set up. Incorrect results can be avoided by placing attenuators close to the EUT.

If the transmitter's RF output cannot be recovered through connection with another similar antenna, the desired output signal can be obtained from the transmitter.

2.3.2.3 SNo. ignal test arrangement at the input of the receiver

Apply Appendix A.2.3 of QCVN 18:2014/BTTTT with the following adjustments.

The desired signal must represent the corresponding normally modulated RF input signal when the receiver operates normally.

To establish an information connection for the desired input signal, it must be applied to the receiver's RF inputs through coaxial cable or waveguide. Appropriate measures must be taken to minimize the effects of unwanted currents on the outer conductors of the coaxial cable or waveguide at the time the EUT is set up. Incorrect results can be avoided by placing attenuators close to the EUT.

If the receiver's RF input cannot be applied through connection with another similar antenna, the desired input signal of the receiver can be obtained. The source of the desired input signal must be placed outside the test environment.

For digital devices, including point-to-multipoint devices, the input signal level must be set at a nominal value of 15 dB above the receiver input level with a bit error rate (BER) of 1 x 10^-5.

The input signal level for analog devices must be set at 15 dB above the reference signal-to-noise ratio input level. If the reference signal-to-noise ratio is not specified in the relevant product standard, the manufacturer's specifications must be used.

These levels are close to normal operating levels and sufficient to avoid wideband noise from power amplifiers that could cause electromagnetic interference affecting the measurements.

2.3.2.4 Signal test arrangement at the output of the receiver

Apply Appendix A.2.4 of QCVN 18:2014/BTTTT.

2.3.3 Excluded bands

Apply Appendix A.3 of QCVN 18:2014/BTTTT.

2.3.3.1 Excluded bands for receivers

The excluded band is the operational band extended by ±5% at each end of the center frequency.

2.3.3.2 Excluded bands for transmitters

Excluded bands shall not be applied when measuring transmitters in standby mode.

For this Standard, the excluded bands need to extend to both ends of the basic transmission frequency but separated from the central emission frequency by 250% of the channel spacing (CHS) related to the agreed radio frequency channel when the system is in operation. When CHS is not determined, the excluded bands need to extend to both ends of the basic transmission frequency but separated from the central emission frequency by 250% of the necessary bandwidth.

2.4 Evaluation无效 Technical requirements

2.4.1 General

Apply Appendix B.1 of QCVN 18:2014/BTTTT.

2.4.2 Equipment capable of providing information connection

The evaluation and test signals as specified in 2.3 apply to radio equipment or radio equipment combined with auxiliary equipment that allows establishing an information connection.

2.4.3 Equipment incapable of providing information connection

If the equipment has specialized characteristics (see 2.5) that do not allow for the establishment of information connections, such as protective switching devices, or independent testing auxiliary equipment (i.e., not connected to radio equipment), the manufacturer must clearly specify the testing methods to determine the level of quality or acceptable quality degradation during and/or after the testing process. The manufacturer must provide a method to assess the quality degradation of the equipment.

The assessment criteria when implemented must be simple but must also provide sufficient evidence that the main functions of the equipment are operating.

2.4.4. Auxiliary Equipment

Apply Appendix B.4 of QCVN 18:2014/BTTTT.

2.4.5. Classification of EquipmentâRadio connection equipment under this standard is only used in fixed installations and powered by AC or DC power sources. Therefore, emission testing and immunity testing requirements apply only to radio equipment and auxiliary equipment used in fixed installations (see QCVN 18:2014/BTTTT, Article 2.1 and Article 2.2, Table 1 and Table 4).

2.5. Quality Criteria

2.5.1. Quality Criteria for Continuous Phenomena applicable to Transmitters (CT) and Receivers (CR)

Apply Appendix C.1 of QCVN 18:2014/BTTTT with the following adjustments: Information connections must be maintained during and after testing."b) In addition to the lists of public services issued according to the provisions of Clause 2, Article 4 of this Decree, specialized agencies under provincial People's Committees shall report to the provincial People's Committee for decision-making on amending, supplementing, or issuing the list of public services funded by the state budget within their jurisdiction and consistent with the local budget capacity within the approved budget by the Provincial People's Assembly, and send it to the Ministry of Finance and relevant ministries and sectors for supervision during implementation." Specific quality criteria for continuous phenomena must apply 2.5.3.

2.5.2. Quality Criteria for Impulse Phenomena applicable to Transmitters (TT) and Receivers (TR)

Apply Appendix C.2 of QCVN 18:2014/BTTTT with the following adjustments: Information connections must be maintained after testing.

Specific quality criteria for impulse phenomena must apply 2.5.3.

2.5.3. Specific Quality Criteria

2.5.3.1 Signal Port Quality

The quality of the equipment must be confirmed for signal ports:"b) In addition to the lists of public services issued according to the provisions of Clause 2, Article 4 of this Decree, specialized agencies under provincial People's Committees shall report to the provincial People's Committee for decision-making on amending, supplementing, or issuing the list of public services funded by the state budget within their jurisdiction and consistent with the local budget capacity within the approved budget by the Provincial People's Assembly, and send it to the Ministry of Finance and relevant ministries and sectors for supervision during implementation." • By measuring the number of error bits caused on the main signal port during all exposures:

• By testing the functionality of the main signal port and other signal ports after exposure;

• By confirming that software and data stored in memory have not changed.

Permitted background errors may occur at any time, testing may be repeated up to three times to determine any correlation between random errors and electromagnetic compatibility phenomena.

2.5.3.1.1 Quality Criteria for Continuous Phenomena

The number of error bits at each individual exposure must not exceed the maximum number of errors specified by the manufacturer for expected operation.

The number of errors is calculated as follows:

(maximum error rate specified by the manufacturer) x (bit rate) x (test duration)

During testing, there must be rest periods between each exposure frequency.

2.5.3.1.2 Quality Criteria for Impulse Phenomena

Frame loss or desynchronization must not occur during individual exposures. The result of electromagnetic stress must be no warning signals generated.

Overvoltage surge testing is not applied where frame loss may occur. For this test, the EUT must operate as intended after stopping the exposure measurement.

2.5.3.2 Analog Voice Frequency Signal Ports

The quality of the equipment must be confirmed for analog voice frequency signal ports:

• By measuring sound signal spikes (demodulated 1 kHz) on the signal port during continuous exposure in both directions of signal flow from analog to digital and from digital to analog;

• By testing the functionality of the main signal port and other signal ports after exposure;

2.5.3.2.1 Quality Criteria for Continuous Phenomena

The noise signal level obtained from the EUT measured with a 600 Ω impedance must not exceed -40 dBm.

2.5.3.2.2 Quality Criteria for Impulse Phenomena

The number of error bits at each individual exposure must not exceed the maximum number of errors specified by the manufacturer for expected operation.

The EUT must automatically return to normal operational state after stopping the exposure measurement.

2.5.3.3 Ethernet Interfaces and Packet Data

The interface operates in packet mode with the following criteria.

2.5.3.3.1 Quality Criteria for Continuous Phenomena

For interfaces designed to transmit third-party data traffic, the selected port must be connected to the testing equipment (such as a data information analyzer) as the sole point-to-point data connection. This will avoid excessive transmission errors caused by data collisions and bus connection issues.

The interface must be implemented correctly and monitored throughout the testing period for frame errors.

During exposure, frame errors must not exceed 5% above the permitted static current threshold.

2.5.3.3.2 Quality Criteria for Impulse Phenomena

Data link connections must be maintained.

2.5.3.4 Service and Maintenance Interfaces

These types of ports are not for permanent connections, and therefore immunity testing is not required. After completing the immunity testing, it must be confirmed that the quality of the ports meets the manufacturer's specifications.

2.5.3.5 Synchronization Interfaces

The quality of subordinate clock ports must be tested with synchronization equipment together with an external source.

2.5.3.5.1 Quality Criteria for Continuous Phenomena

During exposure, synchronization must not be lost.

2.5.3.5.2 Quality Criteria for Impulse Phenomena

No false warning signals should appear after exposure.

Functional quality according to the manufacturer's specifications must be confirmed after exposure.

2.5.3.6 Remote Alarm Interfaces

These interfaces are defined by the manufacturer.

2.5.3.6.1 Quality Criteria for Continuous Phenomena

No false alarm signals should appear during continuous exposure.n l2.5.3.6.2 Quality Criteria for Impulse Phenomena

No false alarm signals should appear after exposure.

2.5.4 Quality Criteria for Independent Testing Auxiliary Equipment

Apply Appendix C.4 of QCVN 18:2014/BTTTT.

Radio transmission equipment in fixed operations and related auxiliary equipment within the scope of regulation stipulated in Article 1.1 must comply with technical regulations in this Standard. đFor sudden phenomena

No false warning signals appear after exposure.

2.5.4. Quality criteria for ancillary equipment đIndependently tested

Apply Appendix C, C.4 of QCVN 18:2014/BTTTT.

3. MANAGEMENT PROVISIONS

Radio transmission equipment in fixed service and related ancillary equipment within the scope of regulation as stipulated in Article 1.1 shall comply with the technical provisions set forth in this standard.

4. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

Relevant organizations and individuals are responsible for implementing the provisions on certification and declaration of conformity for related radio communication devices and shall be subject to inspection by state management agencies in accordance with current regulations.

Chapter 5. ORGANIZATION OF IMPLEMENTATION

5.1. The Telecommunications Administration and Provincial Departments of Information and Communications are responsible for organizing guidance on the implementation of management of radio communication devices in accordance with this Standard.

5.2. In cases where the provisions set forth in this Standard are changed, supplemented, or replaced, they shall be implemented according to the new document.

5.6. During the process of implementing this standard, if any issues arise or difficulties occur, relevant organizations and individuals shall reflect them in writing to the Ministry of Information and Communications (Science and Technology Department) for guidance and resolution.

 

LIST OF REFERENCES

[1] ETSI EN 301 489-4 (V2.2.1): "Electromagnetic compatibility and Radio spectrum Matters (ERM); ElectroMagnetic Compatibility (EMC) standard for radio equipment and services; Part 4: Specific conditions for fixed radio links and ancillary equipment".

 

TABLE OF CONTENTS

Chapter 1. GENERAL PROVISIONS

1.1. Scope of Application

1.2. Applicability

1.3. Referenced Documents

1.4. Terms and Definitions

Chapter 2. TECHNICAL PROVISIONS

2.1. Electromagnetic Compatibility Emission

2.2. Immunity

2.3.1. General Provisions

For the purposes of this standard, test conditions in Appendix A of QCVN 18:2014/BTTTT may be applied when appropriate. This standard supplements additional provisions regarding test conditions for fixed radio transmission equipment and auxiliary equipment in fixed services.

2.3.2. Signal measurement arrangement

2.3.3 Excluded bands

2.4. Evaluation criteria

2.4.1 General

2.4.2 Equipment capable of providing information connection

2.4.3 Equipment incapable of providing information connection

2.4.4. Auxiliary Equipment

2.4.5. Equipment classification

2.5.1. Quality Criteria for Continuous Phenomena applicable to Transmitters (CT) and Receivers (CR)

2.5.1. Quality criteria applicable to continuous phenomena for transmitters (TX) and receivers (RX)

Specific quality criteria for impulse phenomena must apply 2.5.3.

2.5.3. Specific quality criteria

2.5.4. Quality criteria for auxiliary equipment tested independently

3. PROVISIONS VỀ MANAGEMENT

4. RESPONSIBILITIES OF ORGANIZATIONS AND INDIVIDUALS

Chapter 5. ORGANIZATION OF IMPLEMENTATION

LIST OF REFERENCES