---

An alarm transmission system shall be selected from one of ten categories described by this European Standard. An ATS shall be allocated a category which will determine its performance and resilience.

Categories SP1 to SP6 are based on single ATP ATSs.

Categories DP1 to DP4 add resilience by requiring alternate ATPs.Table 1 —ATS configuration

Where an application cannot be satisfied by any of the categories of this standard a new custom category, category C, shall be defined within an application specific standard using parameters from the classes defined in Annex D.

Where a custom category is used reference shall be made to the tables in Annex D instead of the category tables, Table 1 to Table 9. All other requirements of this standard shall apply.

Where there is a requirement for a custom category C, it shall include the rationale for the choice of a custom category and there shall be sufficient documentation for the verification of performance.

A statement shall be made referring to the requirements listed in Tables 1,4, 5 and 6.

Equipment and systems shall meet local, national and European requirements and regulations for attachment to, establishment and termination of connection and transmission via public telephone and data networks and/or the regulations for transmission via the use of radio, power distribution systems or cable TV distribution systems.

6. System requirements

   1. General

The ATS shall provide communication between one or more ASs at one supervised premises and one or more AEs of one or more ARCs.

An ATP may include permanent dedicated links, permanent virtual links or switched links which may use equipment that is not covered by the requirements of EN 50136-2 and EN 50136-3 or may be affected by other applications sharing the transmission links.

An ATP may include:

• a transmission link that is shared with non-alarm data applications,

• a transmission link that carries other ATPs,

• equipment from a third party transmission network provider, which is not located at either the supervised premises or the alarm receiving centre and is not classified as ATE,

• equipment from a third party which is located at the supervised premises but is not classified as ATE.

The performance (reliability) of an ATS may be affected by:

• unwanted, malformed or otherwise malicious incoming data at the interfaces of the SPT or RCT,

• transmission network congestion as a result of transmission link sharing,

• transmission network unavailability due to equipment failure and/or maintenance.

Transmission links shared with other applications shall be arranged such that operation and maintenance does not prevent the ATS from meeting the requirements of this European Standard.

Transmission equipment that is connected between the transmission network interface of the SPT and the transmission network interface of the RCT and/or MCT is not subject to the requirements of EN 50136-2 and EN 50136-3.

NOTE 1 Examples of SPT integrated network interfaces include analogue modems, DTMF transceivers, ISDN terminal adapters, Ethernet modules, and GSM radio modules. No technologies are excluded.

NOTE 2 Equipment at the supervised premises will be subject to the application guidelines provided within CLC/TS 50136-7.

NOTE 3 Local network interface failures may be detected and reported by the SPT to the RCT using the remaining operational transmission path; however interface monitoring cannot be used to provide confirmation that a transmission path is operational.

The ATSP shall provide a statement regarding the number of ASs that can be connected to the ATSN that will ensure compliance with the requirements of Table 2.

Any single ATP shall continue to meet the requirements of the appropriate transmission time and the maximum transmission time of Table 2:

1. at a rate equivalent to one such message per minute from each of a number of ASs representing at least 0,1 % of the system capacity, and

2. at a rate of at least 2 alarms per minute at the RCT interface to the AE.

The evaluation shall be done when the ATSN is in a normal condition with the stipulated rate of messages.

The ATS shall protect itself against Denial of Service (DoS) attacks from the transmission network.

Any form of incoming data or signal received from a transmission network shall not prevent the ATP from performing as specified, unless the amount of incoming data leads to congestion of the transmission link. ATP performance deterioration is not allowed when there is enough remaining network capacity to carry ATP signalling.

Any malicious data received by a transmission network interface, shall not affect the operation of the ATE (SPT, RCT or MCT) or the operation of any other transmission network interface. This applies even if the malicious data rate reaches the capacity of a single interface, rendering the interface itself inoperable.

If the performance of the ATS is affected by a DoS attack, a fault signal shall be generated according to the monitoring and fault reporting requirements of applicable category.

NOTE 1 This requirement is intended to emphasize the need to protect against attacks where malicious data or signalling is used to interfere with the operation of the ATE. These attacks can be performed either by malicious signalling designed to impair the ATE or by overloading the communications with large amounts of data.

NOTE 2 DoS attacks may be present in any network, e g. IP networks, PSTN networks. Examples of such attacks are: devices deliberately overloading the IP network, automatic dialling facilities to overload parts of PSTN networks, jamming devices to interfere with radio communications, etc.

For the categorisation of the ATS the following parameters are used:

• transmission time; average, 95th percentile and maximum;

• reporting time;

• monitoring of interconnections;

• ATSN availability.

The arithmetic mean of the alarm transmission time and 95th percentile of the measurements of the transmission time shall not exceed the values specified in Table 2 for the appropriate category.

Any transmission time exceeding the maximum acceptable transmission time of Table 2 for a specific system shall, for each incident, be classified as a transmission system fault in accordance with NOTE 7.

The time is measured from the time when a change of state occurs or alarm message is presented for transmission at the SPT interface to the AS until the time that the new state or message is reported at the RCT interface to the AE.

The transmission time applies to all changes of state or message that are transmitted from the AS through the SPT interface to the ATS.

NOTE 1 Where the SPT interface to the AS is not accessible the measurement may be made from a more accessible point before the SPT interface to the AS and an appropriate correction applied to the result.

NOTE 2 Where the RCT interface to the AE is not accessible, or where it is more convenient, the measurement may be made to a point after the RCT interface to the AE and an appropriate correction applied to the result.

NOTE 3 Times within the AS and within the AE will be specified in other standards.

NOTE 4 For most ATS(s) there exists a direct relation between the classification of Tables 2 and 3.

NOTE 5 The transmission time includes the time to establish a connection.

Table 2 — Transmission time

Where the transmission time cannot be measured directly then it is acceptable that the round-trip time may be measured. In this case the round-trip time shall meet the same requirements as the transmission time for the appropriate category in Tables 2 and 3.

NOTE 6 The transmission time may not be equal to half the round-trip time.

NOTE 7 The round-trip time is the time measured from when a change of state occurs or alarm message is presented for transmission at the SPT interface to the AS until the time that the positive acknowledge signal or message is presented to the AS (at the SPT interface to the AS).

All of the following links and interconnections of the ATS shall be monitored and faults shall be detected, reported and logged:

• AS to SPT interconnection monitoring this also applies for integrated AS and SPT solutions;

• ATP end-to-end monitoring;

• ROT to AE interconnection monitoring.

In the event of a fault on the interconnection between the AS and the SPT a fault or alarm signal shall be generated and transmitted to relevant AE and if applicable the MCT(s) within the times specified in Table 2 for the appropriate category.

NOTE Where the interconnection used for alarm transmission between the AS and SPT is not available, an independent connection between the AS and SPT can be used to signal that interconnection fault to the AS

The reporting time shall not exceed the values specified in Table 3 for the appropriate ATS category.

Transmission faults shall be presented to the AE and AS as described in Table 4 and Table 5.

All transmission faults shall be presented to the ATSP for appropriate action.

All ATPs shall be monitored in line with the requirements listed in Table 3.

NOTE 1 The frequency of the exchange of status messages should be greater than the reporting times in Table 3 to minimise the generation of false alarms. Where required by the ATS Category, status messages should be encrypted and substitution protected.

NOTE 2 Local network interface failures may be detected and reported by the SPT to the RCT using the remaining operational transmission path; however interface monitoring cannot be used to provide confirmation that a transmission path is operational.

Table 3 — Maximum reporting time

Where an ATS category requires more than one ATP, the ATPs shall use diverse interfaces to connect the SPT to the transmission networks in such a way that a single tamper action on the transmission network cannot cause all ATPs to fail simultaneously.

NOTE 1 For example fixed line alarm transmission path and a radio transmission path using a mobile service provider network.

NOTE 2 Dual path ATS requirements apply to all 'D' categories as defined throughout this standard.

One of the ATPs, of a dual path system, shall be identified as the primary ATP and include a primary ATP reporting time as specified in Table 3.

Whilst the primary ATP is known to be operational the alternative ATP shall not exceed a maximum reporting time as specified in Table 3.

The alternative ATP shall have a maximum reporting time as specified in Table 3 when the primary ATP is failed to make sure the ATS maximum reporting time is not exceeded.

The reporting time for the loss of both ATPs shall not exceed the ATS reporting time defined in Table 3 for the appropriate category.

NOTE 3 As long as service is not lost a single path line fault should be presented to the ATSP, but can be delayed presenting it to the AE where it is agreed between the interested parties (see 6.7.2).

NOTE 4 It is permitted to have more than two paths.

The interconnection between the RCT and the AE shall be monitored. In the event of failure of the interconnection a fault signal shall be recorded and presented to relevant AE and RCT or monitoring centre. The reporting time of the fault signal shall meet the shortest reporting time requirement of any associated ATP.

Messages shall not be lost in the event of power failure or any other event generated internally by the SPT or RCT as for example software reset.

A means shall be provided to confirm that each alarm received at the SPT from the AS, and each alarm generated by the ATS, is delivered correctly to the AE. This may be delivered as either a positive acknowledgement of alarm delivered or a fault message on failure of delivery shall be send to the AS by the SPT.

The ATS is required to report all alarms and path failures as specified in Table 4 for each category to the AE.

In the event of an ATS failure a fault or alarm signal shall be generated and transmitted to relevant AE and if applicable the MCT(s) within the times specified in Table 2 for the appropriate category.

All ATS faults shall be presented to the ATSP for appropriate action.

Table 4 — RCT to AE alarm reporting

Table 5 — SPT to AS alarm reporting

The ATS is required to report all alarms and path failures as for each category specified in Table 5 to the AS.