Tài liệu Điện thoại di động mạng lưới Radio P15 ppt

15 UPT—Universal Personal Telecommunication ∗ People are becoming more mobile. At the same time they have a greater need to be reachable and to be able to reach others. A variety of different systems that address all the different categories of mobility already exist: • Employees can be reached through a DECT terminal anywhere in their company. • Tradesmen can be called over a Digital Communication System (DCS) within a city. • Business people can be reached over the same telephone number via GSM anywhere in Europe, wherever they are located. • Adventurous types are linked to civilization through the INMARSAT satellite system. For each of these communications systems, the user requires a special terminal. In contrast to these radio-based systems, wireline telecommunications sys- tems capable of reaching almost every household in the industrialized countries are available. Fixed networks do not offer users mobility. To be reached at another terminal, the user has to inform the caller of his new location area in the form of a telephone number. With Universal Personal Telecommunication (UPT) the telecommunications network assumes responsibility for establish- ing a user’s location through an interrogation of databases based on a personal telephone number. This provides mobility in telecommunications networks to a larger number of users without the need for special new terminals. 15.1 Classification of Telecommunications Services The services of a telecommunications network first allow users to exchange information over the network in order to communicate. A service is what is ∗ With the collab oration of Matthias Fr¨ohlich Mobile Radio Networks: Networking and Protocols. Bernhard H. Walke Copyright©1999 John Wiley & Sons Ltd ISBNs: 0-471-97595-8 (Hardback); 0-470-84193-1 (Electronic) 774 15 UPT—Universal Personal Telecommunication Figure 15.1: Classification of telecommunications services made available to users by telecommunications authorities and private service providers for communication over public and private networks. The ITU-T distinguishes [20] between two types of service: Bearer services, also called communications services, are used to transfer data between precisely defined user–network interfaces. According to the ISO/OSI reference model, a bearer service is provided by layers 1–3 (the Open Systems Interconnection reference model (OSI-RM, [6, 25]) of the ISO (International Organization for Standardization) describes communication between open systems as seven interrelated layers). An example of this is the socalled B-channel in ISDN with 64 kbit/s of transmission capacity. Teleservices offer users the possibility of communicating with one another over network terminals, and are provided by layers 1–7 of the OSI-RM. This also specifies the communications functions of the terminals. An example of this is the telephone service in ISDN. With both services a separate distinction is made between interactive ser- vices and distribution services, which are subdivided further as shown in Fig- ure 15.1. Services are described according to the service features offered to the user. A differentiation is made between general connection features, basic service features and extended service features (see Figure 15.2). Extended service features are only available in connection with a bearer or teleservice, and can be provided either outside of the network or within the network. Within the network they are subject to standardization and are specifically referred to as supplementary services (see Figure 15.3). Value-added services (VAS) are extended service features that are provided by service nodes outside the network in OSI layers 4–7. These services usually contain storage, call-up or conversion functions for interfaces, protocols and 15.2 Extended Service Features in ISDN and GSM 775 Subscriber service features Basic service features service features specific Information- Connection- specific Fast connection setup Special call completion Special lines Charge display Supplementary information Operations advice and dictionary Number identification Service- specific General connection features Barring Supplementary Figure 15.2: Breakdown of the service features of telecommunications services Provision inside the network defined by standards Additional services Provision outside the network non-standardized Value-added services Available only together with bearer services or teleservices Supplementary service features Figure 15.3: Separation of supplementary service features into additional and value-added services bit-rate adaptation. They require an interface to a bearer or teleservice of the network. Figure 15.4 presents a breakdown of the bearer services, teleservices, sup- plementary services and value-added services in a telecommunications net- work, with S representing the access interface of the user between terminal and network and Q the interface between value-added service and network. 15.2 Extended Service Features in ISDN and GSM The current worldwide success of GSM is due to a great extent to the sup- plementary and value-added services offered. Owing to the harmonization between ISDN and GSM, most of the extended service features of ISDN are also available in GSM. The following section describes the most important supplementary and value-added services of ISDN. The service features offered additionally by GSM will be described in Section 15.2.2. 776 15 UPT—Universal Personal Telecommunication Q Value-added Service S S Ter- minal Transport Network, e.g., ISDN Function for Supplementary minal Ter- Service Module Supplementary Service Teleservice Bearer Service Service Figure 15.4: Breakdown of bearer services, teleservices, supplementary services and value-added services 15.2.1 Supplementary and Value-Added Services in ISDN Because of full digitalization of its network, ISDN offers a variety of supple- mentary services compared with the analogue telephone network, the most important of which can be summarized into seven groups: Number identification displays the telephone number of the party calling or of the party being called. The latter is of interest, for example, when call diversion is being activated. There are ways of keeping these supplementary services secret. In addition, more than one telephone number can be supported on one connection. Call diversion allows an incoming call to be diverted immediately to another number after a brief wait or if a number is busy. Special call completion includes supplementary service features such as call holding for enquiries as well as automatic callback or call-waiting if the number called is busy. Group connections include conference and three-party calls as well as calls for closed user groups. Charge functions allow to bill all or some incoming calls to the called sub- scribers account and to display the charges for these calls. Supplementary information can be exchanged between the terminals using transparent user signalling. Barring functions can be used for suppressing unwanted incoming calls, as well as for restricting specific or all outgoing calls. For the first time, some of the supplementary and value-added services of ISDN are supporting the mobility of users, or, in other words, a person- alization of the services is offered. Thus, for example, call diversion allows 15.2 Extended Service Features in ISDN and GSM 777 incoming calls to be routed to another location, thereby supporting the user’s mobility. Personalization is provided to a limited degree through the exclusive assignment of multiple-access telephone numbers to specific groups of people or the barring of certain telephone numbers for incoming calls. 15.2.2 Supplementary and Value-Added Services in GSM Depending on the system, GSM offers several extended service features that are not supported by ISDN. In particular, these are services that support mobility and personalization directly through the system. The main ones include the following: Device mobility, i.e., the ability to move freely within the radio coverage area of a base station during a call. Because the radio connection is switched automatically (handover), it is even possible to change between any number of adjacent base stations without causing an existing connection to be broken off. Authentication of the user, i.e., establishing and checking the identity in- dependently of the terminal used. A Personal Identification Module (PIM), usually in the form of a smart card, is used along with a Per- sonal Identification Number (PIN). Localization describes the automatic identification and storage of a user’s location area in the network. This allows the user to be reached under his GSM telephone number irrespective of his location. Registration means making available the services subscribed to within the framework of the contract agreed between operator and user (service profile). The costs that are incurred are charged at the same time to the user in accordance with the terms of the agreement. The subscriber’s identity must be clearly established through the authentication process in order to prevent fraudulent use. Personalization of the service profile allows the user to configure certain ser- vice features individually within the framework of the agreed service agreement. Thus, for example, the user could activate or deactivate a voice mail service (automatic answering service in the network) or re- strict his own accessibility by blocking incoming calls because of the extra cost these would occur or to avoid being disturbed. The large number of users subscribing to the GSM network underline the demand for these extended service features, so an effort is being made to support them also in the fixed network—wherever this would be technically feasible. The first step in this direction is the service referred to as Universal Personal Telecommunication (UPT), which is introduced below. 778 15 UPT—Universal Personal Telecommunication 15.3 The UPT Service for Universal Personal Telecommunication The UPT service has been under development since the early 1990s, and was standardized in its outline form through international recommendations [21, 24] of the ITU in 1993. The introduction of the UPT service will take place in several stages, and to date only the first (Capability Set 1 ) has been standardized [26]. In wireline telecommunications networks such as ISDN the telephone num- ber of a user is firmly linked to the network connection of the terminal. All services of the network accessed from this network connection are charged to the user. This fixed relationship between network connection and telephone number of the user will be eliminated with the UPT service. Identification of UPT users is carried out independently of the terminal addressing and the access points of the network. A unique UPT number allows a user to make and receive calls at any access point and from any terminal in the network. A telecommunications network must offer different supplementary services in order to support the UPT service: Personal mobility, which allows a UPT user to make and receive calls us- ing different terminals in accordance with his service agreement (UPT User’s Service Profile). Identification of UPT users on the basis of network-independent UPT num- bers. Charging and billing, which is based on the UPT number independently of the terminal. Uniform access and authentication functions for UPT services in different networks. Security functions for protecting the personal data of UPT users. Configuration functions, which are used by the UPT user and the UPT sub- scriber to tailor the subscribed services to meet individual requirements. The UPT service of the first phase offers these supplementary services in a lim- ited form, and only supports the telephone service in the analogue telephone network, in ISDN and in mobile radio networks. Other restrictions affect the scope of the security functions as well as the access and authentication functions. These supplementary services will be available during the second phase in a less restricted form and, e.g., data services will be supported. However, this phase has not yet been standardized. 15.3 The UPT Service for Universal Personal Telecommunication 779 15.3.1 Existing Studies of the UPT Service The mobile radio system UMTS (Universal Mobile Telecommunications Sys- tem) [2, 29] is being designed to support standardized personalized worldwide user telephone numbers and supplementary services similar to those of the UPT service. Concepts for user administration in UMTS using a distributed database are being developed [28] and quantitively evaluated on the basis of models. Flat directory hierarchies used in connection with the interrogation technique passing are proving to be particularly favourable. The extended service features of ISDN such as call diversion and num- ber identification enable services similar to those of UPT to be implemented through a PC connected to the network access interface of the user. This kind of system is being developed [27] and evaluated on a simulated basis. For comparison purposes, several alternatives to UPT implementations are being simulated and studied in the Deutsche Telekom network. The imple- mentation with a PC at the network access interface of the user is showing clear advantages in terms of waiting times for requested services. However, this does not offer a complete UPT service, because the system does not sup- port UPT calls from non-UPT terminals. 15.3.2 Further Development of UPT The introduction of UPT into existing telecommunications networks is a dy- namic development process. The fundamental objectives mentioned in Sec- tion 15.3 are to be seen as guidelines that should be considered in any further development of UPT [30]. Figure 15.5 shows the phases projected in the development of UPT. These show a differentiation between essential and optional service features. Es- sential service features must be available at the outset of the corresponding development phase, whereas the offering of optional service features depends on the decisions made by the UPT provider. A certain proportion of the ser- vice features in both groups have already been standardized. The others have already been developed to a degree and are awaiting future standardization. 15.3.3 Phase 1—Scenario with Limited UPT Functionality During the introductory phase, UPT is limiting itself to PSTN (Public Switched Telephone Network), ISDN (Integrated Services Digital Network) and possibly the Public Mobile Telephone Service. Only voice telephone ser- vices are being offered. UPT phase 1 does offer limited service features for security and user-friendliness. According to the projected plan, the first phase has been completed at the end of 1993. UPT phase 1 functions are already available in the IN operating tests being conducted worldwide. Phase 1 is to be carried out without any intervention in existing networks, if possible. 780 15 UPT—Universal Personal Telecommunication Figure 15.5: Timetable for the development and standardization of UPT service features 15.3.4 Phase 2—Scenario with UPT Basic Functionality Phase 2 does offer UPT subscribers additional service features and supports a larger number of networks. During this phase, UPT also linked up with GSM networks and connection-oriented data networks. Smart cards and card read- ers offer users improved security against fraudulent use by outsiders. Phase 2, which was completed in 1995, is using the technology of intelligent networks. 15.3.5 Phase 3—Scenario with Extended UPT Functionality Phase 3 is offering extended UPT functionality. This phase was not specified in detail, but only regarded as a target for UPT to allow a more effective integration of new technological developments and an opportunity to respond to the economic developments of UPT services. Phase 3 results were projected for late 1997, and are available since then. 15.3.6 Service Features of UPT in Phase 1 of its Introduction As already explained, the ITU-T is considering some of the service features are being essential and others as being optional. Four service features in phase 1 are essential for the implementation of UPT [21]: 15.4 Business Relationship between UPT Users and Providers 781 Figure 15.6: Business relationshipment between conventional telephone subscriber and system provider • Authentication of a UPT user’s identity protects both the UPT provider and the user from unauthorized use of the UPT service. • In-call registration enables a UPT user to notify the network of the location area where he can be reached through a terminal. This regis- tration can be restricted to a specific period of time or revoked through an explicit deregistration or new registration. It is possible for several subscribers to be registered at the same terminal. • An outgoing UPT call allows a UPT user to use a terminal and have the call charged to his bill. So long as no follow-on service feature is avail- able, an authentication must be carried out for each UPT call in order to prevent fraudulent use. The service feature follow indicates to the network that other calls are following the outcalls. New authentication is then not necessary. • In-call delivery refers to the call forwarding service. The UPT subscriber makes his location known to the network beforehand through an in-call registration. The incoming call is then forwarded to this terminal. The subscriber to the network connection must be able to prevent registra- tion and call forwarding at his terminal. Access to UPT functions using registration is shown in Section 15.4.2. 15.4 Business Relationship between UPT Users and Providers To be able to use the telecommunications services, users must enter into a business relationship with the provider. Three different market participants can be identified in the conventional monopolistic telecommunications market. Figure 15.6 identifies these three business partners as: 782 15 UPT—Universal Personal Telecommunication UPT Service Provider (UPT + Framework Service) Network Operator (Bearer Services) Service Provider Services) (Tele-, Supplementary, Value-added Subscriber User Access Provider Figure 15.7: UPT business relationships • The network operator who provides network access and the communi- cations network • The subscriber to the service • The service provider of the applications who contributes to the value- added service in the network The user has a direct business relationship with the network operator. With UPT there is a complicated situation from the view of the user (see Figure 15.7). In addition to • a network operator, a user and an applications service provider, there are also • a UPT service provider, a network access provider and a subscriber to the UPT services who are involved in the UPT service arrangements. A business relationship no longer exists between subscriber and network operator. Instead, a subscriber can order the UPT services from a UPT service provider. In the case of private individuals, this subscriber will be the user himself. With companies, the organization appears as the subscriber to the UPT services that it makes available to its employees through proper registration in the user service profile. Since users usually do not use their own terminals (mobility), it is important that a relationship exists with a network access provider who can provide access to the network. A deregulation of the telecommunications market is necessary in order to enable the relationship between user and network operator to be split up. A similar situation was observed with the mobile radio networks in Europe, where users acquire mobile radio services from a service provider. The service provider is not automatically also the network operator. [...]... telephone number can provide a direct indication of where user B is located with a direct dialling system A telephone number therefore has a direct relationship to the location of user B, and also determines how a call is routed through the network Because of the individual numbers that make up the telephone number, the switching centre is able to route the call to user B In addition to addressing users,... determining the cost of a call According to newer tariffing models there will be probably only two national tarif zones in the future: local and long distance Then there will be no more advantage for the user to di erentiate from the destination code where the long-distance call party is located, and the acceptance of the indirect dialling system will grow Numbering and Dialling 791 CIPHB G FDB E C ¢)¤@... 15-digit combination of numbers without any discernible structure as a personal telephone number for UPT For example, whereas until now user A has been able to reach eight di erent users in the same local network using a six-digit telephone number and five di erent users in other local networks but with possibly the identical national destination code, this same user will now have to remember 13 di erent... agreement on how the same UPT indication numbers are used According to the scenarios discussed, the UPT number would also have to be changed if there is a change in UPT service provider because the UPT indicator for the service provider would be di erent There is a strong commitment to remaining with a provider because of the costs involved in making 15.8 Numbering and Dialling 795 a number change This... Instead, as mentioned above, GSM networks are di erentiated from the PSTN through separate dialling codes which function as a traffic discrimination feature 15.8.3 UPT The ITU presents proposals for UPT numbering in Rec E.168 [13] In these proposals a UPT number is defined as a user’s unique identification, and is dialled by a caller to reach the user The UPT indicator is the part of the UPT number that identifies... call and therefore will be handled and charged in a special way • A UPT number must be as short as possible to minimize the number of digits to be dialled • It must be possible to dial the UPT number from any terminal in the PSTN Therefore digits have already been reserved (digits 0 9 and possibly the characters # and *) • UPT users should be able to retain their UPT numbers if they change service provider... service provider instead of the local network This concept has already be applied in the integration of GSM mobile radio networks For example, the first NDC digit can select the UPT service while the other digits would be responsible for the selection of the UPT service provider Numbering and Dialling 793 6 @¥ 9 7 ¦86 ¦¥ ¡ 15.8 89 9 £¡ ¤¢  %&$" $ ' 0  52%¨ 0 "21' )( 43' 0  "$2%¨ 0 "21' )( )¨ (... length of the telephone number to be dialled therefore depends on the distance between the two communicating parties Special services can be selected by dialling special prefixes before the actual telephone number of the person being called A 1 is reserved as the first digit for this purpose For example, the GSM networks in Germany are accessed from the fixed network through dialling a 17x Telecommunications... telecommunications services This gives the telephone number economic significance along with its technical importance This direct control has now been replaced by indirect dialling systems, which is why it is necessary to establish an association between telephone number and location of user B In an indirect dialling system the routing of a call is largely separate from the telephone number A path established from... functions Distributed functional plane (DFP) A service-independent building block (SIB) is implemented by one or several functional entities (FE) in the distributed functional plane [17] The interaction between two functional entities takes place through information flow (IF) Figure 15.22 shows the functional entities of the distributed functional plane and how they are linked Functional entities are divided . telephone number can provide a direct indication of where user B is located with a direct dialling system. A telephone number therefore has a direct relationship to. number of digits to be dialled. • It must be possible to dial the UPT number from any terminal in the PSTN. Therefore digits have already been reserved (digits