Gaode Uninhabited Area Project: Satellite Rescue and Offline Navigation Technologies

In China, more than 300 million explorers are curious about uncharted routes, with 70% of the territory still unmapped and over 1,200 rescue teams ready to protect lives.

On August 28, 2024, Gaode launched the Uninhabited Area project, introducing two core features: “Satellite Rescue” and “Offline Navigation”.

Satellite Rescue enables emergency signals to be sent from the Gaode app to satellites, even when no terrestrial network is available. Gaode integrates satellite‑capability SDKs from major phone manufacturers, standardizes the interface, and builds a unified two‑way satellite communication solution. User‑generated natural‑language rescue messages are encoded into a 36‑bit payload using bit‑wise separation, bit‑operations, and Base64 encoding, allowing the full rescue request to fit within the limited bandwidth.

The system also provides real‑time network switching among cellular, Wi‑Fi, and satellite links (including Tiantong and Beidou), handling protocol compatibility, interruption detection, and automatic recovery. End‑to‑end encryption and intelligent anomaly detection ensure communication security, while map data and satellite status are fused to offer comprehensive decision support (coordinates, altitude, optimal routes).

A “Rescue Chatroom” aggregates nearby rescuers and volunteers, sharing precise location and movement routes, which has been shown to improve rescue efficiency by 50%.

Offline Navigation tackles two scenarios: no network signal and no road‑network coverage. The team uses a quadtree spatial index to dynamically partition unmapped areas, achieving over 70% storage compression and reducing query complexity from O(n) to O(log n). By analyzing failed network requests from many users, the system predicts “no‑network zones” and pre‑caches navigation data in the background.

Two caching strategies are employed: scheduled Wi‑Fi downloads for planned trips, and on‑the‑fly caching when a user leaves Wi‑Fi but is about to enter a no‑network zone. Frequently used data (home, common routes) are retained, while least‑used data are evicted to balance memory usage.

Seamless switching among online, weak‑network, and offline modes is achieved by either offline route calculation using big‑data pre‑processing or by reusing cached routes when the user’s position is close to a previously computed path.

The technologies were field‑tested in four extreme regions of Inner Mongolia (Kubuqi Desert, Jiufeng Mountain, Yinshan, and Siziwang Banner), validating both satellite rescue and offline navigation in real‑world harsh environments.