Mesh Time and State Synchronization
Distributed TDMA Slot Sync and Routing State Replication
Distributes time reference and synchronizes network state (neighbor tables, routing tables, contact plans) across all mesh nodes to coordinate TDMA slot timing, avoid collisions, and maintain consistent routing decisions.
Purpose
Maintain microsecond-level slot timing alignment across the mesh and eventual-consistency of routing/cluster state so that nodes operate cooperatively despite asynchronous startup, sleep cycles, and link interruptions.
Context
Pulls master time from L3-COM-TIME-DIST and propagates via beacon timestamps; reconciles state using gossip protocols. Supports L3-COM-MESH-NODE (TDMA framing) and L3-COM-MESH-ROUT (consistent routing decisions).
Principles
- ▸Time synchronization across mesh uses periodic beacon with timestamp; nodes apply offset and frequency drift correction (NTP-style algorithm)
- ▸PTP (IEEE 1588-2019) with White Rabbit High Accuracy profile achieves sub-nanosecond sync over fiber; RF link reaches ~1 µs typically
- ▸Gossip protocols (e.g., epidemic dissemination) provide eventually-consistent state replication tolerant to network partitions
- ▸TDMA requires slot alignment within ~10% of slot duration; for 10 ms slot, ~1 ms tolerance — easily met by RF beacon sync
- ▸Byzantine-fault-tolerant consensus (e.g., HotStuff, PBFT) used when state correctness must be guaranteed against arbitrary node failures
- ▸Lamport/vector clocks track logical event ordering when wall-clock sync is degraded
Typical implementations
- ▸PTPd, LinuxPTP — open implementations of IEEE 1588
- ▸White Rabbit Project (CERN) — IEEE 1588-2019 High Accuracy profile, used at LHC, GSI, financial sector
- ▸Software Defined Synchronization in CCSDS Proximity-1 mesh
- ▸Apache Cassandra / Akka cluster gossip — examples of eventually-consistent state
- ▸DTN routing tables refreshed via Bundle-in-Bundle Encapsulation (RFC 9173)
Lunar considerations
- ▸RF propagation delays at lunar surface (≤50 µs at 15 km range) are deterministic and can be precisely compensated
- ▸Asymmetric paths (different uplink/downlink routes through mesh) introduce timing skew — measurable via two-way beacon exchange
- ▸Sleep modes on mobile mesh nodes (rovers, sensor outposts) require fast resync upon wake — coarse sync from ephemeris, fine sync from beacons
- ▸Solar particle events may cause coordinated SEU bursts that desync many nodes simultaneously — needs robust re-sync protocol
- ▸Mesh time fallback to L3-COM-TIME-USOC if local oscillator drifts beyond threshold
Specifications
Functional
| primary function | Distribute master time and replicate routing/cluster state across mesh nodes |
| inputs | Master timestamp from L3-COM-TIME-DIST, Beacon receipts with timestamps from peers, State updates from L3-COM-MESH-ROUT (routing changes), Sleep/wake events from individual nodes |
| outputs | Corrected local time offset applied to each node's clock, Replicated routing table view across mesh, TDMA frame boundary signals to L3-COM-MESH-NODE, Time-quality and consistency metrics telemetry |
| time sync accuracy us | 10 |
| state convergence time s max | 60 |
| beacon interval s | 10 |
| supported clock drift ppm | 50 |
| max supported nodes | 256 |
Physical
| mass kg | 0.0 |
| dimensions | Software running on each mesh node and CDH |
| materials | Code on rad-hard NOR flash |
| operating temperature c | -40, 70 |
Operational
| power consumption w | 0.5 |
| thermal range c | -40, 70 |
| lifetime years | 100 |
| mtbf hours | 500000 |
Interfaces
Provides
- Corrected local time, TDMA slot boundaries
- Synchronized routing state and neighbor tables
Requires
- Master timestamp and 10 MHz reference
- Beacon receive timestamps and Doppler estimates
Cite this entry
Lunar Ark Codex. "Mesh Time and State Synchronization" (L3-COM-MESH-SYNC). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-COM-MESH-SYNC
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.