6.42 Mobile base station relays

22.2613GPPRelease 18Service requirements for the 5G systemTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

6.42.1 Description

The requirements below refer to a “mobile base station relay”, which is a mobile base station acting as a relay between a UE and the 5G network, i.e. providing a NR access link to UEs and connected wirelessly (using NR) through a donor NG-RAN to the 5G Core. Such mobile base station relay is assumed to be mounted on a moving vehicle and serve UEs that can be located inside or outside the vehicle (or entering/leaving the vehicle).

NOTE: The radio link used between a mobile base station relay and served UEs, as well as between mobile base station relay and donor RAN, is assumed to be NR-Uu; in that regard, it should be clear that a mobile base station relay is different than a UE relay (which uses instead a PC5-based link to provide indirect connection to remote UEs).

Few main underlying assumptions are:

– requirements cover single-hop relay scenarios as baseline (multi-hop is not precluded);

– legacy UEs are supported;

– other stage-1 requirements (e.g. on wireless self-backhaul), as well as existing stage-2/3 functionalities and architecture options (e.g. IAB) do not assume or address full relay mobility (e.g. relays on board of moving vehicles), thus cannot cover the requirements below, which are intended to be specific to mobile base station relays;

– the identified requirements do not intend to imply or exclude specific network/relay architectures and topology solutions (e.g. could be IAB based, or others);

– the MNO managing mobile base station relays, and the RAN/5GC they connect to, can be a PLMN or an NPN operator.

6.42.2 Requirements

The 5G system shall support efficient operation of mobile base station relays.

The 5G system shall be able to support means, for a mobile network operator, to configure, provision and control the operation of a mobile base station relay, e.g. activation/deactivation, permitted location(s) or time of operation.

The 5G system shall be able to support provisioning and configuration mechanisms to control UEs’ selection and access to a mobile base station relay, e.g. based on UE’s authorization, geographic or temporary restrictions, relay’s load.

The 5G system shall be able to support RAN sharing between multiple PLMNs for UEs connected to the 5G network via mobile base station relays.

NOTE 1: the above requirement assumes both relay and (donor) RAN resources, including UE access link and relay backhaul link, are shared among operators.

The 5G system shall be able to configure and provision specific required QoS for traffic relayed via a mobile base station relay.

NOTE 2: QoS is end-to-end, i.e. from UE to 5GC.

Subject to regulatory requirements and based on operator policy, the 5G system shall support means to configure and expose monitoring information of a mobile base station relay to an MNO’s authorized third-party.

The 5G system shall be able to provide means to optimize network behaviour to efficiently deliver data based on the mobility information (e.g., itinerary), known or predicted, of mobile base station relays.

The 5G system shall be able to support communication from/to users of one MNO (MNO-A) via mobile base station relays, where the traffic between the relay and the MNO-A network is transported using 5G connectivity (RAN and 5GC) provided by a different MNO (MNO-B).

NOTE 3: The 5G connectivity provided to the MNO-A relays by the different MNO (MNO-B) assumes a generic wireless backhaul transport, independent from the mobile base station relay functionalities.

The 5G system shall be able to support UEs connectivity to RAN using simultaneously, a link without mobile base station relay and a link via a mobile base station relay, or simultaneous links via different mobile base station relays.

NOTE 4: The above requirements cover scenarios were the two links (to the RAN) could be connected to the same or different RAN node(s), and assuming both relay(s) and RAN belong to the same PLMN.

The 5G system shall be able to provide means to support efficient UE cell selection and cell reselection (between mobile base station relays or between relays and RAN) in the presence of mobile base station relays.

The 5G system shall be able to ensure end-to-end service continuity, in the presence of mobile base station relays.

NOTE 5: The above requirement intends to cover different scenarios of UE mobility (e.g. UE moving between two mobile base station relays, or between macro RAN and relay) and relay mobility (e.g. base station relay moving between different donor RAN nodes).

The 5G system shall be able to support mechanisms to optimize mobility and energy efficiency for UEs located in a vehicle equipped with a base station relay.

NOTE 6: The above requirements cover scenarios where mobile base station relays provide 5G access for both UEs in the vehicle and around the vehicle.

The 5G system shall be able to support incremental deployment of connectivity by means of one or a series of mobile base station relays for use only in specific locations where UEs would receive no other 3GPP access (terrestrial or non-terrestrial) coverage, e.g., for public safety scenarios.

The 5G system shall be able to support mobile base station relays using 3GPP satellite NG-RAN (NR satellite access).

The 5G system shall be able to support mobile base station relays accessing to 5GC via NR satellite access and NR terrestrial access simultaneously.

The 5G system shall be able to support service continuity for mobile base station relays using at least one 3GPP satellite NG-RAN.

NOTE 7: This requirement applies to scenarios where there is a transition between two 3GPP NG-RAN, operated by the same MNO, involving at least one 3GPP satellite NG-RAN.

The 5G system shall be able to identify and differentiate UEs’ traffic carried via a mobile base station relay and collect charging information, including specific relay information (e.g. geographic location served by the relay).

The 5G system shall support means for a mobile base station relay to have a certain subscription with a HPLMN, used to get access and connectivity to the HPLMN network (via a donor RAN).

The 5G system shall support the ability of a base station relay to roam from its HPLMN into a VPLMN.

The 5G system shall support mechanisms, for the HPLMN controlling a mobile base station relay, to enable/disable mobile relay operation if the relay is roaming in a VPLMN.

The 5G system shall support mechanisms to disable mobile relay operation by a VPLMN where a mobile base station relay is roaming to.

The 5G system shall be able to fulfil necessary regulatory requirements (e.g. for support of emergency services) when UEs access the 3GPP network via a mobile base station relay.

The 5G system shall be able to support priority services (e.g. MPS) when UEs access the 3GPP network via a mobile base station relay.

The 5G system shall be able to support location services for the UEs accessing 5GS via a mobile base station relay.

The 5G system shall ensure that existing end-to-end 5G security between the UE and 3GPP network is unaffected when the UE accesses the 3GPP network via a mobile base station relay.

The 5G system shall be able to minimize radio interference possibly caused by mobile base station relays.

The 5G system shall minimize the impact of the presence of mobile base station relays on radio network management (e.g. through automatic neighbour cell list configuration).

6.43 Tactile and multi-modal communication service

6.43.1 Description

The tactile and multi-modal communication service can be applied in multiple fields, e.g. industry, robotics and telepresence, virtual reality, augmented reality, healthcare, road traffic, serious gaming, education, culture and smart grid [38]. These services support applications enabling input from more than one sources and/or output to more than one destinations to convey information more effectively. As figure 6.43.1-1 illustrates, the input and output can be different modalities including:

Video/Audio media;
Information received by sensors about the environment, e.g. brightness, temperature, humidity, etc.;
Haptic data: can be feelings when touching a surface (e.g., pressure, texture, vibration, temperature), or kinaesthetic senses (e.g. gravity, pull forces, sense of position awareness).

Figure 6.43.1-1. Multi-modal interactive system

For immersive multi-modal VR applications, synchronization between different media components is critical in order to avoid having a negative impact on the user experience (i.e. viewers detecting lack of synchronization), particularly when the synchronization threshold between two or more modalities is less than the latency KPI for the application. Example synchronization thresholds [41] [42] [43] [44] are summarised in table 6.43.1-1.

Table 6.43.1-1: Typical synchronization thresholds for immersive multi-modality VR applications

Media components	synchronization threshold (note 1)
audio-tactile	audio delay: 50 ms	tactile delay: 25 ms
visual-tactile	visual delay: 15 ms	tactile delay: 50 ms
NOTE 1: for each media component, “delay” refers to the case where that media component is delayed compared to the other.

6.43.2 Requirements

The 5G system shall enable an authorized 3rd party to provide policy(ies) for flows associated with an application. The policy may contain e.g. the set of UEs and data flows, the expected QoS handling and associated triggering events, other coordination information.

The 5G system shall support a means to apply 3rd party provided policy(ies) for flows associated with an application. The policy may contain e.g. the set of UEs and data flows, the expected QoS handling and associated triggering events, other coordination information.

NOTE: The policy can be used by a 3rd party application for coordination of the transmission of multiple UEs’ flows (e.g., haptic, audio and video) of a multi-modal communication session.