Inductive Latent Context Persistence: Closing the Post-Handover Cold Start in 6G Radio Access Networks

TL;DR

This paper introduces ILCP, a method that preserves mobility context across handovers in 6G RANs, significantly reducing ping-pong handovers and improving decision accuracy by transmitting compressed state information.

Contribution

ILCP models RAN as a dynamic graph, compresses and transports user state to address post-HO cold start, and demonstrates substantial improvements over measurement-only and baseline models.

Findings

ILCP achieves 0.0% ping-pong HOs versus 6.5% baseline.

Post-HO accuracy improves by +5.1 percentage points.

ILCP runs at 7.7 ms per handover decision on a GTX 1080.

Abstract

In modern radio access networks (RANs), rule-based handover (HO) decisions (e.g., A3/A5) depend on user equipment (UE) measurements only, so UEs at the same location can receive inconsistent HO outcomes. GNN-based methods improve HO KPIs using richer context than measurements alone. However, recurrent or graph models discard the per-UE recurrent state at HO and reinitialize at the target next-generation Node B (gNB), losing mobility history and forcing the target model to rebuild from post-HO measurements only. We address this post-HO cold start with Inductive Latent Context Persistence (ILCP), compressing the source recurrent state, transporting it on the 3GPP Xn as a 128-byte payload, and adapting it at the target gNB. We model the RAN as a dynamic heterogeneous graph over UE nodes, gNB nodes, measurement edges, and Xn edges. On a Vienna 4G/5G drive-test, ILCP achieves 0.0% ping-pong HOs versus 6.5% for an identical no-transfer baseline and 22.6% for a Transformer baseline; post-HO accuracy improves by +5.1 pp on average (peak +13.3 pp) in the 50-250 ms window. On one NVIDIA GTX 1080 (8 GB), ILCP runs end-to-end at 7.7 ms p99 per handover decision. Under perturbations (shadow fading, NLOS blockage, SSB-burst sparsity), robustly trained ILCP keeps handover failure (HOF) in the 10-13% range. Under the same fixed-reference-label setting, A3/A5 rises from 1.1% to 57-65% HOF when measurements are perturbed, exposing limits of measurement-only rules.