5G • 5G-Advanced (Rel-18)
Sidelink Relay Phase 2
Multi-Hop and Remote Terminal Sidelink Relaying
Allows a device outside network coverage to relay its cellular connection through an intermediate vehicle or smartphone to reach the cell tower.
Technical Explanation
When a firefighter enters a reinforced concrete basement, cellular signal drops completely. Rel-18 Sidelink Relay Phase 2 enables the firefighter's device to discover a nearby vehicle parked on the street and relay data over PC5; the vehicle then forwards the traffic over its standard 5G Uu connection, maintaining seamless two-way connectivity.
Key Functions
- Extends cellular network coverage into underground basements, tunnels, and disaster ruins
- Utilizes intermediate vehicles or handheld devices as mobile relay proxies
- Supports seamless Layer-2 and Layer-3 relay discovery, authentication, and forwarding
- Provides vital lifeline communication for emergency search and rescue teams
Specifications
3GPP TS 38.300, TS 23.304 (Rel-18)
Interfaces
PC5 (Relay)Uu
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