Since the industrial age, engineering design has become an extremely demanding activity. Collaborative and concurrent engineering occur as a concept and methodology at the end of the last century and was defined as a systematic approach to integrated and co-design of products and their related processes. The diversity and complexity of actual products, requires collaboration of engineers from different geographic locations to share the ideas and solutions with customer and to evaluate products development. VR and AR technologies have found their ways into critical applications in industrial sectors such as aerospace engineering, automotive engineering, medical engineering, and also in the fields of education and entertainment. The range of technologies include Cave Automatic Virtual Environment (better known by the recursive acronym CAVE) environments, reality theatres, power walls, holographic workbenches, individual immersive systems, head mounted displays, tactile sensing interfaces, haptic feedback devices, multi-sensational devices, speech interfaces, and mixed reality systems 
One of the key challenges is to how to enable a distributed virtual environment (DVE) allowing multiple users from different geographical locations (some of them are present at the same location) to interact over a network. A DVEs is defined as multi-user virtual reality that actively support communication, collaboration, and coordination , 3D place-like environment in which participants are provided with graphical embodiments called avatars that convey their identity, presence, location, and activities to others . A DVE is the simultaneous existence of multiple users in the same virtual space represented as avatars, their communication, the shared exploration of 3D visualizations, and the collaborative construction of new content. This avatar representation is essential for every user knows about the actual perceptions of other users. The users can communicate with each other. They can interact with other users and with the virtual environment. A DVE in the terms of this study is a location agnostic service experience.
To support DVEs for collaborative and concurrent engineering, the 5G system needs to fulfil certain KPIs, such as latency, data rate, reliability. Moreover the 5G system (with mobile metaverse services) is expected to support the fundamental features including:
mobile metaverse media support among multiple users;
User Identity management;
Novitas, an innovative start-up company, has set up a distributed virtual environment (with the corresponding 5G communication subscriptions provided by GreenMobile) for collaborative and concurrent engineering in their product design with engineers participating locally and remotely. They have been granted a contract to work together with several partner companies to design and produce a new model of aeroplane engine.
In the current phase, Novitas need to collaborate closely with Nyhet, a partner company, to design the key parts of the engine. As part of the agreement, they use the distributed virtual environment to carry out some of the design that requires interaction among engineers. Some engineers use mobile phones or computers (as well as the necessary XR devices), with the corresponding 5G communication subscriptions, to attend such engineering meetings. To protect the sensitive business information, strict security requirements for user identity management and data security are crucial.
The service flows below illustrate how engineers interact with each other using services provided by 5G system.
Archimedes, Isambard, Leonardo and George have scheduled an XR design meeting, and Archimedes, Isambard, Leonardo attend from offices while George attends from the factory. Each participant needs to be authenticated before being admitted to the meeting. Due to the strict security requirements, typically participants need to be authenticated using bio information (e.g. finger print, facial image) at the terminal side. The result (not the original bio information) of the terminal side authentication can be forwarded to the corresponding application server of the enterprise. The final result of the network level authentication (can also include the context information, e.g. location information of the participants) is also forwarded to the corresponding application server of the enterprise. Such information helps the enterprise to decide what information (e.g. levels of confidentiality) can be disclosed to which participants during the meeting.
Having completed the authentication of the participants, the multimedia communication session/sessions are set up among multiple users as well as the associated devices in the mixed reality systems (e.g. head mounted displays, tactile sensing interfaces, haptic feedback devices, multi-sensational devices). This can be done by means of the IMS (including IMS CN with Data Channel capability) or via OTT applications.
When a session starts, multiple streams are established over the 5G network between the corresponding devices that carry multiple modalities data. Table 5.3.3-1 depicts the typical QoS requirements that have to be fulfilled in order for the users' QoE to be satisfactory.
The haptic information, video and voice are generated at one party and distributed to all other parties continuously. Note that based on the company security policy, some information is shielded before being distributed to certain participants. For example, George joins the meeting from the factory, which is considered less secure according to the company policy. Consequently some sensitive information is filtered before being distributed to George. Information filtering is typically done at the conference centre (i.e. conference focus).
George travels back to office while staying connected on the conference. The connection quality of George's devices has deteriorated sharply, and the 5G network triggers the codec re-negotiation to maintain the reasonable quality of experience for all participants.
The 5G system enables efficient communication, with enhanced security and identity management, in support of DVEs for the collaborative and concurrent engineering.
The service requirements on the support of multimedia communication among multiple users have been captured in TS 22.228
with the following key definitions:
An IP multimedia session with two or more participants. Each conference has a "conference focus". A conference can be uniquely identified by a user. Examples for a conference could be a Telepresence or a multimedia game, in which the conference focus is located in a game server.
A conference with interactive audio-visual communications experience between remote locations, where the users enjoy a strong sense of realism and presence between all participants by optimizing a variety of attributes such as audio and video quality, eye contact, body language, spatial audio, coordinated environments and natural image size.
A set of functions, devices and network elements which are able to capture, deliver, manage and render multiple high quality interactive audio and video signals in a Telepresence conference. An appropriate number of devices (e.g. cameras, screens, loudspeakers, microphones, codecs) and environmental characteristics are used to establish Telepresence.
The conference focus is an entity which has abilities to host conferences including their creation, maintenance, and manipulation of the media. A conference focus implements the conference policy (e.g. rules for talk burst control, assign priorities and participant's rights).
Support of Multi-device and Multi-Identity in IMS MMTEL service is captured in clause 4.6 of TS 22.173
The support of multiple devices is inherent in IMS. In addition, a service provider may allow a user to use any public user identities for its outgoing and incoming calls. The added identities can but do not have to belong to the served user. Identities may be part of different subscriptions and different operators.
In addition, TS 22.101
has specified in clause 26a
a set of service requirements on User Identity:
Identifying distinguished user identities of the user (provided by some external party or by the operator) in the operator network enables an operator to provide an enhanced user experience and optimized performance as well as to offer services to devices that are not part of a 3GPP network. The user to be identified could be an individual human user, using a UE with a certain subscription, or an application running on or connecting via a UE, or a device ("thing") behind a gateway UE.
Network settings can be adapted and services offered to users according to their needs, independent of the subscription that is used to establish the connection. By acting as an identity provider, the operator can take additional information from the network into account to provide a higher level of security for the authentication of a user.
The 3GPP System shall support to authenticate a User Identity to a service with a User Identifier.
The functional requirement and performance KPIs in support of XR applications are mainly captured in TS 22.261
Clause 8 of TS 22.261
specifies the security related requirements covering aspects such as authentication and authorization, identity management, and data security and privacy.
Additional consideration need to be given to allow multiple users from different geographical locations to interact using XR techniques.
The 5G system is able to collect charging information per UE or per application for the use of IMS based conferencing services.