[System Design] GPS Location Ingestion at Scale: gRPC Streaming, MQTT & Kalman Filter in Ride-Hailing

Uber and Grab's ride-hailing systems handle 1.25 million GPS write operations per second from 5 million drivers. HTTP REST fails at this scale due to per-request overhead. gRPC streaming and MQTT with Protobuf serialization and Kalman Filter noise reduction cut network calls by 67% while maintaining sub-200ms latency. Engineers should consider using persistent connections and efficient protocols for high-volume location data ingestion.