Operators may want to migrate towards an IP based network architecture. Since the transition to an All IP networkwill not happen overnight, both traditional mobile circuit switched telephony and IP based services need be supported by a single network simultaneously. It is believed that circuit switching will live for many years together with IP services. Also there will be a large number oflegacy terminals to be supported. Also, because of real-life limitations on how quickly change occurs in networks and the mix of terminals in the network, operators may find that they must have an architecture to support different kinds of terminals and roaming between networks. It is unlikely that all networks will develop at the same speed. Hybrid architecture may be best for the majority of the operators because it allows low-risk evolution from the current networks, while enabling a full service offering.Release 2000 shall support service offerings being independent from transport technology.
The 3GPP release 2000 shall be based on an evolved Release 1999.
GSM (and UMTS) succeed in a competitive marketplace due to the consistent provision of a rich diversity of high quality services. The enabling mechanisms which allow deployment of these services is transparent to the user. This is shown in Figure 1 below.
Figure 1. Transparent provision of services
Services may be categorized as basic, supplementary, operator specific, or multimedia. These categories of services may be transparent to users. Different enabling mechanisms may be used to provide services. This is shown in figure 2.
Figure 2: Different types of services and enabling domains
With succeeding releases, new and improved services and enabling mechanisms are developed and deployed. In general, most users not experience a reduction in the available service set, or degradation in the quality of the offered services. This is depicted in Figure 3.
Figure 3: Succeeding releases provide new and improved services and enabling mechanisms
In Release 2000, new and improved enabling mechanisms and services will be made available. Additionally, a network option will enable the provision of services without using circuit switched enablers (the All-IP network option). In this case, the set of services available to the user, and the quality of the offered services will be no less than that available in Release 2000 networks which use circuit switched enablers. This is shown in figure 4.
Editor's note: some operators prefer identification of a minimum set of CS services in the PS domain, whereas others preferred support of all Release 99 services. Requires agreement and consensus.
Figure 4: All-IP network option
4.4 Teleservices and multimedia services
A Release 2000 network may have both a circuit domain and packet domain, or a hybrid circuit domain and packet domain network infrastructure. In addition to teleservices available from Release 99 new services, termed multimedia services, will the available as part of Release 2000. Multimedia services may also enable enhanced usage and management of teleservices. The relationship between these tele/multimedia services, and the circuit/packet transport domains may be logically depicted as shown in Figure 5.
Figure 5: Teleservices and multimedia services
The logical relationship between the teleservices and multimedia services to the circuit and packet domains is subsequently described.
The “A” relationship refers to the existing relationship between the teleservices and the circuit switched based domains.
The “B” relationship refers to the support of teleservices in a packet domain. The same set of end user services may be provided across both the “A” and the “B” relationships. The existence of “B” relationship would be transparent to the end user from both a service capability and a user interface perspective. The “B” relationship could be a path for the evolution of GSM to packet based (IP) networks.
Editor's note: to verify from S2 that circuit services may be provided by the PS domain (e.g. offered by MSC servers)
The “C” relationship refers to the relationship between the multimedia services and packet domain. The “C” relationship is not merely the evolution of the 2G services and mobile terminals to the 3G environment, but also represents a new category of services, mobile terminals, services capabilities, and user expectations. Service Providers are not required to provide the existing supplementary services of the “A” and “B” relationships across the “C” relationship, although some comparable services (e.g. emergency services) may be required. Any new multimedia service which may have a similar name or functionality to a comparable standardised service, does not necessarily have to have the same look and feel from the user's perspective of the standardised service. However, the “C” relationship should provide sufficient capabilities to allow a Service Provider to develop and implement Release 2000 versions of these services that would have the same user inteface and quality of service to the end user. Voice communications is one, but not the only, real-time multimedia service that would be provided across the “C” relationship.
The “D” relationship refers to the relationship between the multimedia services and circuit domain (e.g. H.324 supported in Release 99).