Open problems in harmonized terrestrial–non-terrestrial 6G integration

Investigate multi-orbit mobility, cross-domain synchronization, and migration from terrestrial and non-terrestrial assets already in orbit within a harmonized 6G terrestrial–non-terrestrial network architecture.

Background

The paper presents non-terrestrial networks as a native component of 6G rather than as a supplementary 5G overlay. A unified design must coordinate heterogeneous propagation conditions, device types, and multiple orbital regimes while remaining compatible with existing deployed satellite assets. The authors explicitly characterize multi-orbit mobility, cross-domain synchronization, and migration from assets already in orbit as the open problems that remain after the basic feasibility of terrestrial–non-terrestrial integration has been established.

References

Terrestrial-only system models therefore look increasingly like the special case, and the open problems have moved past feasibility to multi-orbit mobility, cross-domain synchronization, and migration from assets already in orbit.

— 6G as It Is Actually Being Built: Insights from Early 3GPP Standardization  (2610.05694 - Tu et al., 5 Oct 2026) in Section 5, “New 6G Capabilities: Integrated Sensing and Non-Terrestrial Networks”