Description
Bluetooth Low Energy (BLE) is the low-power, advertisement-driven branch of the Bluetooth standard introduced in Bluetooth 4.0 (2010). It is the second wireless modality of the thesis: BLE-calibrated CSI crowd sensing depends on BLE advertisements (RSSI fingerprints, beacons) for ground-truth crowd density and trajectory information that CSI alone cannot recover. BLE 5.1 added angle-of-arrival / angle-of-departure direction-finding, which raises BLE's localization accuracy from metre-scale (RSSI) to sub-metre (AoA). For the thesis this is the modality that supplies labelled training and drift-detection data to the otherwise unsupervised CSI pipeline.
Specs / capabilities
- 2.4 GHz ISM band, 40 channels (3 advertising + 37 data)
- Up to 2 Mbps PHY (BLE 5.0+)
- Advertising packets readable by any BLE scanner (passive)
- BLE 5.1+: AoA / AoD direction finding via switched antenna arrays + Constant Tone Extension (CTE)
- BLE Mesh (5.0+) for routed multi-hop networks
- mW-scale TX power; coin-cell-sufficient
Tooling
- nRF Connect / nRF Sniffer (Nordic Semiconductor)
- BlueZ (Linux), ESP32 BLE stack, Apple Core Bluetooth
- iBeacon / Eddystone advertisement formats
- Direction-finding kits: Nordic nRF52833 DK + AoA antenna arrays
Used by (papers)
- BLE RSSI fingerprinting papers (used as comparison baseline / fusion partner with CSI)
- BLE 5.1 AoA localization papers
- Indoor crowd-counting papers that combine BLE proximity with CSI