Adds a complete simulation harness for the MeshCore radio platform, including:
### ADAPTIVE routing strategy (sim/src/RoutingStrategies.h)
Hash-based relay gate selects a deterministic subset of nodes to forward each
flood, with relay percentage adapted to local neighbour density:
- SPARSE (<=4 neighbours): 100% relay -- no redundancy to spare
- MEDIUM (5-14): 25% relay
- DENSE (>=15): 15% relay
Selection uses hash(packet_seed XOR node_seed) with no coordination required.
Different packets select different subsets for stochastic load balancing.
Relay suppression: nodes cancel queued outbound TX if they overhear another
node already relaying the same flood (matched by packet hash).
### DensityEstimator (sim/src/DensityEstimator.h)
Passive sliding-window neighbour count from normal traffic -- no extra messages.
Only counts direct senders (hop_count==1) over a configurable window (default 60s).
Uses std::unordered_set for unique counting; no fixed-array cap.
### Adaptive TX power saving (sim/src/SimNode.h)
power_save_enabled reduces TX power in DENSE/MEDIUM tiers:
DENSE: configurable (default 10 dBm, saves 75% TX current vs 20 dBm)
MEDIUM: configurable (default 14 dBm, saves 60% TX current)
SPARSE: always full power -- every hop counts on marginal links
Validated: 100% delivery maintained at -10dBm DENSE reduction. Energy savings
~35% radio total. TX power reduction also lowers area RF noise floor.
### Scenario suite (sim/scenarios/)
scenario_adaptive: ADAPTIVE vs DEFAULT vs PATH_SNR_HYBRID comparison
scenario_concurrent: 2-8 simultaneous flood sources
scenario_longchain: 20-hop chains at marginal SNR
scenario_mixed: ADAPTIVE + legacy DEFAULT interoperability
scenario_dutycycle: EU 1% duty cycle enforcement validation
scenario_relay_pct_sweep: grid sweep to find optimal DENSE%/MEDIUM% operating point
scenario_txpower: TX power saving vs delivery rate vs energy trade-off
### Key empirical results
FM50 ADAPTIVE vs DEFAULT: equal delivery rate, -65% airtime, -70% collisions
CH20 (chain): ADAPTIVE = SPARSE throughout, identical to DEFAULT
TX power MODERATE (-10dB): 100% delivery, -35% energy across all topologies
Legacy interop: zero delivery regression with mixed firmware
### Bug fixes
- DensityEstimator: replace seen[64] array with unordered_set (was capping at 64 neighbours)
- SimBus::onTransmit: add len > 255 guard before memcpy into 255-byte buffer
- SimNode p_forward gate: >= -> > (was silently dropping relays at p_forward=1.0)
- SimNode TX power reset: remove redundant !power_save_enabled clause
- scenario_concurrent: fix stale ConcurrentResult* pointer after vector reallocation
- scenario_relay_pct_sweep: update TxCallback from 4-arg to 5-arg (tx_power_dbm)
- scenario_adaptive: remove unused variable last_suppressed
Co-Authored-By: Claude Sonnet 4.6 <[email protected]>
Friday
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