/ˈbluːtuːθ/
n. "Short-range wireless PAN standard using FHSS in 2.4GHz ISM band for piconet/scatternet device pairing."
Bluetooth, short for Bluetooth, enables cable replacement via frequency-hopping spread spectrum (FHSS) across 79 x 1MHz channels (2.402-2.480GHz), forming piconets (1 master/7 slaves) with TDD/TDMA access and LFSR-derived hopping sequences for interference immunity. Classic (BR/EDR=3Mbps GFSK) handles audio streaming while Bluetooth Low Energy (LE=2Mbps, BLE 5.4=4.4Mbps coded PHY) targets IoT sensors with 1.6-188ms intervals—pairs via LAPU authentication using 128-bit keys unlike WiFi's WPA3.
Key characteristics of Bluetooth include: FHSS 1600 hops/sec across 79/40 LE channels evading 2.4GHz WiFi interference; Piconet Topology 1M:7S with 7.5ms slots (625μs classic); Adaptive Frequency Hopping (AFH) blacklists jammed channels; LE PHY GFSK/PSK/M=4 up to 2.4Mbps with 125/250Kbps coded PHYs; Secure Pairing legacy (PIN), Secure Simple (OOD), LE Secure Connections (P-256 ECDH).
Conceptual example of Bluetooth usage:
/* BLE 5.0 Central scanning for heart rate sensor */
#include <bluetooth/bluetooth.h>
#include <bluetooth/hci.h>
#include <bluetooth/hci_lib.h>
int main() {
int dd = hci_open_dev(0); // HCI device 0
hci_filter_clear(&nf);
hci_filter_set_ptype(HCI_SCANO_REQ_IT, &nf); // LE scan
setsockopt(dd, SOL_HCI, HCI_FILTER, &nf, sizeof(nf));
// Scan 10.24s interval for BLE advertisements
struct hci_dev_info di;
hci_devinfo(dd, &di);
le_set_scan_enable(dd, 0x01, 0x01, 100); // Active scan
// Parse HR measurement (0x180D service)
uint8_t hr_value = advertisement; // BPM in 8-bit field
printf("Heart Rate: %d BPM\n", hr_value);
hci_close_dev(dd);
return 0;
}Conceptually, Bluetooth creates personal area networks via master-slave hopping synchronized to clock—audio A2DP streams over classic BR/EDR while BLE GATT services expose sensors to smartphones without WiFi infrastructure. Mesh topologies (BLE 5.0+) relay via advertiser/relay nodes, stress-tested with PRBS-like packet error rates unlike SerDes BERT validation; powers wireless keyboards, TWS earbuds, and fitness trackers where <1mW average power trumps USB4's gigabit throughput.