Pub/Sub in the Air: A Novel Data-centric Radio Supporting Robust Multicast in Edge Environments

Peer communication among edge devices (e.g., mobiles, vehicles, IoT and drones) is frequently data-centric: most important is obtaining data of desired content from suitable nodes; who generated or transmitted the data matters much less. Typical cases are robust one-to-many data sharing: e.g., a vehicle sending weather, road, position and speed data streams to nearby cars continuously. Unfortunately, existing address-based wireless communication is ill-suited for such purposes. We propose V-MAC, a novel data-centric radio that provides a pub/sub abstraction to replace the point-to-point abstraction in existing radios. It filters frames by data names instead of MAC addresses, thus eliminating complexities and latencies in neighbor discovery and group maintenance in existing radios. V-MAC supports robust, scalable and high rate multicast with consistently low losses across receivers of varying reception qualities. Experiments using a Raspberry Pi and a commodity WiFi dongle based prototype show that V-MAC reduces loss rate from WiFi broadcast's 50-90% to 1-3% for up to 15 stationary receivers, 4-5 moving people, and miniature and real vehicles. It cuts down filtering latency from 20μs in WiFi to 10μ s for up to 2 million data names, and improves cross stack latency 60-100× for TX/RX paths. We have ported V-MAC to 4 major WiFi chipsets (including 802.11 a/b/g/n/ac radios), 6 different platforms (Android, embedded and FPGA systems), 7 Linux kernel versions, and validated up to 900Mbps multicast data rate and interoperation with regular WiFi. We will release V-MAC as a mature, reusable asset for edge computing research.

I. Introduction

Peer communication among mobiles, vehicles, IoT and drones in the emerging edge computing environment is highly dynamic. Which nodes and what data exist nearby are usually unknown beforehand. Heterogeneous, densely deployed sensors (e.g., cameras, radars, lidars, IMUs, temperature/humidity/presence) produce rich varieties of data. Under constant and possibly high mobility (e.g., moving vehicles, flying drones), neighbors within communication range can change in seconds.