By Dr Sebastian Robitzsch, InterDigital Europe Ltd
It is anticipated that 6G standardisation will start in 2025 and the industry is already sharpening their tools, noticeable in the various 6G-related themes at exhibitions, panels and conferences to kickstart the conversation what 6G is all about. In particular, the pre-standardisation work is already running at full steam in bodies such as ETSI and NGMN, focusing on technologies and requirements. With the first phase of 6GIA’s SNS projects kicked off earlier this year, such as PREDICT-6G, the European community is contributing to the global 6G technology and standardisation process.
Any conversation around the “next G” is rooted in its requirements and use cases, followed by Key Performance Indicators (KPIs) to quantify any “next G” technology against the promises made. 6G is no different in that approach and 3GPP has already seen numerous technical reports which study services that can be categorised as 6G, when looking at the 2025 timeframe.
One of the dominant use cases in that regard is one or a mix of augmented, virtual, extended reality (AR/VR/XR) services, which demand the typical KPIs around throughput, latency, jitter, reliability, etc. to be further pushed to new limits. 3GPP is working on a feasibility study for these services [1] and Table 1 provides a summary assessment for KPIs. In addition to the work in 3GPP, the IETF MOPS WG [2] also provides additional values which have been folded into the KPIs in Table 1. As can be seen, three service types have been identified, i.e. video, audio and haptic, and a set of KPIs with detailed upper bound numbers for each of them.
Table 1: Key Performance Indicators for Remote Collaboration [1,2].
| KPI | Video | Audio | Haptics |
| Throughput [kbit/s] | 2500 – 200000 | 64 – 512 | 512 – 1024 |
| Jitter [ms] | ≤ 30 | ≤ 30 | ≤ 2 |
| Latency [ms] | ≤ 100 (lip sync limit)
≤ 150 (preferred) ≤ 400 (limit) |
≤ 150 | ≤ 50 |
| Packet Loss [%] | ≤ 1 | ≤ 1 | ≤ 10 |
| Update Rate [Hz] | ≥ 30 | ≥ 50 | ≥ 1000 |
| Packet Size [bytes] | ≤ MTU | 160 – 320 | 64 – 128 |
| Reliability [%] | 99.9 | 99.99999 | 99.999999 |
However, one can certainly argue that 5G is capable to deliver on these KPIs from a technology perspective, considering the option of private network deployments (aka Non-Public Networks), which enable fine-tuned network deployments towards service-specific packet deliveries [3]. That is why the added KPIs in [1], around inter-service-type delay numbers defining upper bound numbers of how much later a service type can arrive after another one, can be considered as impossible to request and deliver in 5G systems. Additionally, pre-standardisation bodies such as NGMN and 5G-PPP share a common understanding beyond a purely KPI-driven conversation on 6G requirements via added Key Value Indicators (KVIs)[4,5]. The rational here is to allow a value-driven conversation around innovations in 6G instead of a KPI one. And PREDICT-6G is not different in that regard by focusing on the three pillars of deterministic communications, i.e. predictability, reliability and time sensitivity; these three pillars are considered in a multi-domain scenario and in an end-to-end fashion.
When considering the KPIs provided in Table 1 and adding the ability to deterministically control the communication on the User Plane, the KVI conversation around the “added value” to 6G becomes the centre argument and a key differentiator to 5G. Thus, AR/VR/XR use cases provide an ideal narrative for the importance of deterministic communications in PREDICT-6G and the wider pre-standardisation community.
| [1] | 3GPP, “Technical Report 23.856: Feasibility Study on Localized Mobile Metaverse Services (Release 19)”, Nov 2022. |
| [2] | R. Krishna and A. Rahman, “Media Operations Use Case for an Extended Reality Application on Edge Computing Infrastructure”, Online: https://datatracker.ietf.org/doc/draft-ietf-mops-ar-use-case/ |
| [3] | 5G-PPP Technology Board, “Non-Public-Networks – State of the art and way forward”, Nov 2022. Online: https://5g-ppp.eu/wp-content/uploads/2022/11/WhitePaperNPN_MasterCopy_V1.pdf |
| [4] | NGMN, “6G Requirements and Design Considerations”, Feb 2023. Online: https://www.ngmn.org/wp-content/uploads/NGMN_6G_Requirements_and_Design_Considerations.pdf |
| [5] | 5G-PPP, “Beyond 5G/6G KPIs and Target Values”, Jun 2022. Online: https://5g-ppp.eu/wp-content/uploads/2022/06/white_paper_b5g-6g-kpis-camera-ready.pdf |
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