What are the RF design differences between Sigfox, LoRa, and NB-IoT?
Sigfox vs LoRa vs NB-IoT RF
The three LPWAN technologies represent different trade-offs between RF complexity, performance, and ecosystem, and the choice depends on the specific application requirements.
Selection Guide
(1) Choose Sigfox when: the device needs the simplest, cheapest RF design. The application requires only uplink (sensors reporting data). The coverage area has Sigfox network availability. Very few messages per day are sufficient (< 140). (2) Choose LoRa when: private network deployment is preferred (no subscription). Bidirectional communication is needed (downlink for commands/configuration). Data rate flexibility is needed (SF7-SF12 adaptation). The application requires more than 140 messages per day. (3) Choose NB-IoT when: licensed-spectrum reliability is required (no interference from other ISM devices). Deep indoor/underground coverage is needed (164 dB MCL with repetitions). Global cellular roaming is required. Higher data rate (26-62 kbps) is needed. The device must integrate with cellular infrastructure (SIM, roaming, operator management).
LoRa: 125 kHz, CSS, -137 dBm (SF12), $3-6
NB-IoT: 180 kHz, QPSK, -141 dBm, $5-15
All: link budget 156-164 dB
Spectrum: ISM (Sigfox/LoRa) vs licensed (NB-IoT)
Frequently Asked Questions
Which technology has the longest range?
All three achieve comparable maximum range (10-50 km LOS) because their link budgets are similar (156-164 dB). The range differences come from deployment (antenna height, environment) rather than technology. In dense urban: NB-IoT has an advantage due to repetition coding and existing cellular tower infrastructure. In rural: LoRa at SF12 and Sigfox can reach 15-30 km from a well-placed gateway.
Can I switch between technologies later?
Switching requires a hardware redesign: the RF transceiver and antenna are different for each technology. However: multi-protocol modules exist: Quectel BG95 (NB-IoT + LTE-M + GNSS). Nordic nRF9160 (NB-IoT + LTE-M + GNSS). Using LoRa + NB-IoT in the same device requires two RF chains (different frequencies, different protocols). For flexibility: design the PCB with footprints for both options, using a modular SoM (System on Module) approach.
What about power consumption?
Sleep current: Sigfox ≈ 0.5-1 μA, LoRa (SX1262) ≈ 0.16 μA, NB-IoT ≈ 1-5 μA (PSM mode). TX current: Sigfox ≈ 45 mA (14 dBm), LoRa ≈ 45-120 mA (14-22 dBm), NB-IoT ≈ 200-350 mA (23 dBm). LoRa has the lowest sleep current, which is the dominant factor for battery life in infrequent-reporting applications. NB-IoT has the highest TX current but the shortest TX time (higher data rate). For applications with 1 transmission per hour: all three achieve 5-10+ year battery life on 2× AA cells.