1、CEPT T/SF*54*E 87 W 232b434 0009443 1i W TISF 54 E Page 1 Recommendation T/SF 54 (Copenhagen 1987) QUALITY OF SERVICE CATEGORIES FOR TELECOMMUNICATION SERVICES Recommendation proposed by Working Group T/WG 7 “Services and facilities“ (SF) Text of the Recommendation adopted by “Teleconmimications” Co
2、rnmission : Preamble In the past Quality of Service has tended to be the result of chosen technical realizations. In future it is desirable that Quality of Service requirements should be based upon considerations of user expectations, technical feasibility and cost. This Recommendation proposes Qual
3、ity of Service Categories for use in such studies. “The European Conference of Posts and Telecommunications Administrations, considering 1. that users of Telecommunication services are interested in the quality of service irrespective of how that service 2. that two related features have been identi
4、fied: Quality of Service (QOS) and Network Performance (NP), 3. that QOS is a statement of the performance of the service offered to the user, 4. that NP parameters describe the performance attributes of the network and its component parts and are independent of terminal performance and user actions
5、. NP parameters should be regarded as tools for the Administration and are set for the purposes of system design, configuration, management and operation and maintenance, Note. The specification of NP parameters is not the subject of this Recommendation. 5. that for some QOS parameters there can be
6、a mapping against one or more NP parameters. Where there is a one to one mapping the corresponding parameter values may not necessarily be equivalent. In some other cases, the QOS parameters will need to be mapped to a combination of the performance of the terminal equipment and the network, 6. othe
7、r QOS parameters indicate the performance and efficiency of the service providers organisation rather than the performance of its networks, and these may be difficult to harmonise, is provided or of the systems architecture, secommends 1. that a set of Generic QOS Categories for all Telecommunicatio
8、n services should be identified: Such a set of Categories is given in Annex 1. This set should form the basis for the continuing study of QOS of all services, O 2. that for each service specific QOS parameters should be derived from the Generic Categories, as appropriate for that service. The parame
9、ters should be user perceivable and defined in user oriented terms. Because the quality perceived by users is affected by human factors, the parameters which depend on human factors should be indicated. However, other parameters should also be defined which depend only on technical aspects. Those pa
10、rameters for which values are likely to be harmonised should be measurable at the service access point. It is recognised that for some services not all of the Categories will be applicable, 3. that the quantification of QOS parameters should take account of the commercial and regulatory framework ex
11、isting in individual countries, 4. that QOS parameters and their values for existing services should be taken into account when dening similar new services. In general an improvement in quality is desirable and for some parameters a large improvement is desirable and possible. Nevertheless, economic
12、 aspects must also be applied.” Edition of January 15, 1988 CEPT T/SF*54*E 87 m 232b4l14 00094Y4 3 m T/SF 54 E Page 2 GENERIC QOS CATEGORTES Users of Telecommunication services are interested in the quality of service irrespective of how that service is provided or of the systems architecture. Conse
13、quently QOS parameters should be specified in system independent terms appropriate to the service concerned. As a common base for all telecommunication services, a set of “Generic QOS Categories” has been recommended. These categories relate to the different aspects of a particular service are descr
14、ibed below and listed in the order as perceived by the user: 1, PROVISION, ALTERATION, CESSATION AND RECOVERY OF SERVICE (Note 2) Statements or parameters under this category refer to the speed of response in meeting a request by a potential customer/existing customer for the provision/alteration/ce
15、ssation/recovery of service. 2. LOSS OF SERVICE This category refers to the probability, over a specified period of time, of loss of service when usage is requested. Parameters under this category should take account of the fact that terminal equipment may not necessarily be supplied by the service
16、provider. It will be necessary to state the different conditions which qualify as lo of service. 3. CALL ESTABLISHMENT PHASE This category refers to the period commencing with the user indicating his requirement to establish a call, and ending with the system indicating that the call has been establ
17、ished, or cannot be etablished. Parameters under this category will refer to particular segments of the period as appropriate. 4. INFORMATION TRANSFER PHASE Parameters under this category will refer to the: i) Retention of the call and its preservation against unauthorised intrusion until the system
18、 is requested to break it down, or until certain criteria are satisfied that require the system to break-down the call. ii) Capability of the service to transfer information, and the variations that may occur within that capability. 5. CALL RELEASE PHASE This category refers to the period, either fr
19、om a users indication to the system that the call is no longer required, or from the systems determination that the call should no longer be retained, until another call can be initiated or received. Parameters under this category will refer to the speed and correctness of call release. 6. BILLING I
20、NTEGRITY (Note 2) Statements or parameters under this category refer to the certainty that charges in respect of provision, rental, alteration and usage of a service are correct. Note 1. It is recognised that the quality of some aspects of services (e.g. Operator Assistance, Directory Inquiries, etc
21、.) influence the users perception of overal quality of those services. Categories for such aspects have not been included in this Recommenda- tion for the following reasons: - These aspects may be included within the service definition of a specific telecommunications service and/or be common to - T
22、he parameter values for such categories are likely to be difficult to harmonise internationally since they are largely Note 2. Values for parameters in the provision, alteration, cessation and recovery and billing integrity categories are also likely to be difficult to harmonise because they are also dependant on organisational aspects. It may only be possible to adopt harmonised statements under these categories. a number of them. dependent on “human factors” and organisational aspects. Edition of January 15, 1988
