diff --git a/doc_resources/gateway/class_diagram.puml b/doc_resources/gateway/class_diagram.puml
new file mode 100644
index 0000000..3501363
--- /dev/null
+++ b/doc_resources/gateway/class_diagram.puml
@@ -0,0 +1,37 @@
+@startuml
+skinparam linestyle ortho
+
+class Gateway {
+    - gateway_id: str
+    - mqtt_broker: str
+    - mqtt_port: int
+    - service_uuid: str
+    - mqttc: MQTTClient
+    --
+    + KEY_WINDOW: 0x01
+    + KEY_HUMIDITY: 0x02
+    + KEY_TEMP: 0x03
+    + KEY_CO2: 0x04
+    --
+    + decode_payload(data: bytes): dict
+    + publish(mac: str, data: dict)
+    + on_device_found(device, adv_data)
+    + run()
+}
+
+class BleakScanner {
+    + start()
+    + stop()
+}
+
+class MQTTClient {
+    + connect()
+    + publish()
+    + tls_set()
+    + username_pw_set()
+}
+
+Gateway --> BleakScanner : uses
+Gateway --> MQTTClient : uses
+
+@enduml
diff --git a/doc_resources/gateway/sequence_diagram.puml b/doc_resources/gateway/sequence_diagram.puml
new file mode 100644
index 0000000..bac4ec4
--- /dev/null
+++ b/doc_resources/gateway/sequence_diagram.puml
@@ -0,0 +1,30 @@
+@startuml
+skinparam sequenceMessageAlign center
+
+participant "Thingy:52" as thingy
+participant "Gateway\n(Raspberry Pi)" as gw
+participant "MQTT Broker\n(RabbitMQ)" as broker
+participant "Database\n(InfluxDB)" as db
+
+== Startup ==
+gw -> gw : load config.json
+gw -> broker : connect (MQTTS, TLS, auth)
+broker --> gw : connected
+gw -> gw : start BLE scan
+
+== Data collection ==
+loop every 2 min to 6 hours
+    thingy -> thingy : read sensors
+    thingy -> gw : BLE advertising packet\n(key/value payload)
+    gw -> gw : filter on UUID ef680100
+    gw -> gw : decode_payload()\n0x02 humidity\n0x03 temperature\n0x04 CO2
+    gw -> gw : add UTC timestamp
+    gw -> broker : publish JSON\n{gateway_id}/{mac}/update
+    broker -> db : store measurement
+end
+
+== Node failure ==
+thingy ->x gw : no advertising for > 6h
+gw -> broker : node considered dead\n(missing from next publish)
+
+@enduml