Spanda

Connectivity

Spanda extends the existing network and communication systems with first-class wireless connectivity modeling, verification, and failover.

Connection types

Type	Description
WifiConnection	Wi-Fi link state
BluetoothConnection / BleConnection	Bluetooth classic and BLE
CellularConnection, LTEConnection, FourGConnection, FiveGConnection	Cellular links
EthernetConnection, MeshConnection	Wired and mesh backhaul
NetworkStatus, SignalStrength, Bandwidth, Latency, PacketLoss, RoamingStatus	Link metrics

Namespaces: std.connectivity, std.wifi, std.cellular, std.network.

Hardware profiles

Declare available radios on a hardware target:

hardware RoverV2 {
  connectivity [
    WiFi6,
    Bluetooth5,
    LTE,
    GPS
  ];
  network { bandwidth: 100 Mbps; latency: 15 ms; }
}

spanda verify checks that deployment targets expose required connectivity.

Requirements

Use requires_connectivity alongside requires_network:

requires_connectivity {
  gps: required;
  wifi: optional;
  cellular: required;
  latency <= 100ms;
  bandwidth >= 5 Mbps;
  packet_loss <= 1%;
}

Triggers

on network.disconnected { buffer_telemetry(); }
on cellular.roaming { reduce_bandwidth_usage(); }

Failover policies

connectivity_policy RoverNetwork {
  preferred: wifi;
  fallback: cellular;
  emergency: bluetooth;
  switch_if latency > 200ms;
  switch_if packet_loss > 5%;
}

When the fallback link is also impaired by active simulation faults (for example NetworkOutage or LteOutage), the runtime automatically escalates to the emergency link in the same failover step.

Offline and degraded modes

mode offline { disable_cloud_ai(); buffer_telemetry(); }
mode weak_signal { use_compressed_telemetry(); }

on network.disconnected { enter offline_mode; }

Simulation faults

Fault	Effect
NetworkOutage, LteOutage, SatelliteOutage	Zero bandwidth, high latency
WeakWifi	Reduced bandwidth
NetworkLatencySpike, LatencySpike	2 s latency
FiveGHandoff	Brief latency increase
BluetoothDisconnect	Removes BT from profile
PacketLoss	10% packet loss

Timed faults: fault GPSLost at T+30s;, fault NetworkLatencySpike duration 10s;

Security capabilities

Capability	Purpose
network.status	Read link state
wifi.connect	Join Wi-Fi networks
cellular.connect	Read robot.sim_identity() (SIM/eSIM attestation)
network.failover	Switch preferred link
bluetooth.scan, bluetooth.pair	Bluetooth discovery and pairing

See also: Bluetooth, Cellular, Positioning.

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