Bluetooth vs Wi-Fi vs LoRa vs Zigbee: Choosing a Wireless Link
Every wireless project eventually faces the same question: which radio? A smart-home switch, a fitness band, a farm soil sensor and a CCTV camera have very different needs. The four technologies most used by students and makers, Bluetooth Low Energy, Wi-Fi, LoRa and Zigbee, each sit at a different point in the trade-off between data rate, range and battery life.
This article compares them using the theory from earlier articles: bandwidth, modulation, receiver sensitivity and link budget. It finishes with a worked LoRa bit-rate calculation and a decision table.
The Basic Trade-off
Recall that receiver noise floor is -174 dBm/Hz + 10 log10(B) + NF. A radio that uses a wide channel to move lots of data lets in more noise, so it needs a stronger signal and therefore gets less range for the same transmit power. A radio that sends slowly in a narrow channel, or spreads each bit over a long time, can decode much weaker signals. That single idea explains most of the comparison below: Wi-Fi is fast and short-range, LoRa is slow and long-range, and BLE and Zigbee sit in between with a strong focus on low power.
The Four Technologies
Bluetooth Low Energy (BLE)
BLE works in the 2.4 GHz band with 40 channels of 2 MHz, three of which (37, 38 and 39) are used for advertising. It uses GFSK at 1 Mbit/s, with an optional 2 Mbit/s PHY and a long-range coded PHY at 500 or 125 kbit/s since Bluetooth 5. Devices sleep most of the time and wake briefly to exchange small packets, so coin-cell operation for months or years is realistic. Its biggest advantage is that every smartphone can talk to it directly. Classic Bluetooth, a separate mode, is still used for audio streaming.
Wi-Fi (IEEE 802.11)
Wi-Fi uses 20 MHz or wider channels in the 2.4 GHz and 5 GHz bands, with OFDM and QAM to reach tens to hundreds of Mbit/s. It connects straight to an existing router and the internet using TCP/IP, which makes it ideal for cameras, dashboards and anything streaming data. The cost is power: associating with an access point and keeping a connection alive draws far more energy than BLE or Zigbee. The ESP32 and ESP8266 made 2.4 GHz Wi-Fi the default for mains-powered hobby IoT.
Zigbee (IEEE 802.15.4)
Zigbee builds a mesh network on the IEEE 802.15.4 radio, which in the 2.4 GHz band offers 16 channels (11 to 26) at 250 kbit/s using O-QPSK. Mains-powered routers relay messages, so coverage grows as you add devices; battery end devices sleep and talk only to a parent. Smart bulbs, switches and sensors from many brands use it, coordinated by a hub. Thread, used with Matter, runs on the same 802.15.4 radio with an IP-based network layer.
LoRa and LoRaWAN
LoRa is a chirp spread spectrum modulation from Semtech that works in sub-GHz licence-free bands: 865 to 867 MHz in India, 863 to 870 MHz in Europe and 902 to 928 MHz in the United States. By spreading each symbol over a long chirp, it can decode signals below the noise floor, giving kilometres of range from a few tens of milliwatts. LoRaWAN is the network protocol on top: end nodes send to gateways, which forward packets to a network server over the internet. Common modules include the SX1276 and SX1262 families, and Ra-02 boards based on the SX1278 are widely sold for 433 MHz.
Side-by-Side Comparison
| Feature | BLE | Wi-Fi (2.4 GHz) | Zigbee | LoRa |
|---|---|---|---|---|
| Standard | Bluetooth Core spec | IEEE 802.11 b/g/n/ax | IEEE 802.15.4 + Zigbee stack | Semtech LoRa PHY + LoRaWAN |
| Band | 2.4 GHz | 2.4 GHz (and 5 GHz) | 2.4 GHz (sub-GHz options exist) | Sub-GHz (865-867 MHz India) |
| Modulation | GFSK | OFDM with up to high-order QAM | O-QPSK with DSSS | Chirp spread spectrum |
| Raw data rate | 125 kbit/s to 2 Mbit/s | Tens to hundreds of Mbit/s | 250 kbit/s | About 0.3 to 5.5 kbit/s at 125 kHz |
| Typical range (rough, environment dependent) | Tens of metres | Tens of metres indoors | Tens of metres per hop, extended by mesh | Kilometres; more with clear line of sight |
| Topology | Point-to-point, broadcast, mesh profile | Star around access point | Mesh | Star of stars via gateways |
| Power | Very low | High | Low | Very low (long sleep, short bursts) |
| Internet access | Through phone or gateway | Direct | Through hub | Through gateway and network server |
Worked Example: LoRa Bit Rate and Spreading Factor
LoRa's speed is set by the spreading factor SF (7 to 12), the bandwidth BW and the coding rate CR. Each symbol carries SF bits and lasts 2^SF / BW seconds.
Symbol time: Ts = 2^SF / BW Bit rate: Rb = SF x (BW / 2^SF) x CR CR = 4/5, 4/6, 4/7 or 4/8 SF7, BW = 125 kHz, CR = 4/5: Ts = 128 / 125000 = 1.024 ms Rb = 7 x (125000 / 128) x 0.8 = 5469 bit/s SF12, BW = 125 kHz, CR = 4/5: Ts = 4096 / 125000 = 32.8 ms Rb = 12 x (125000 / 4096) x 0.8 = 293 bit/s
Going from SF7 to SF12 cuts the bit rate by a factor of about 19 but greatly improves sensitivity, which is how LoRa trades speed for range. A 20-byte payload is 160 bits, so even ignoring preamble and header it needs at least 160 / 293 = 0.55 s on air at SF12, compared with about 29 ms at SF7. Long airtime costs battery and increases collisions, so LoRaWAN networks push nodes to use the lowest SF that still reaches a gateway.
Which One Should You Use?
| Project | Best fit | Reason |
|---|---|---|
| Wearable or sensor talking to a phone app | BLE | Phones support it natively; coin-cell friendly |
| Camera, web dashboard, OTA updates at home | Wi-Fi | High throughput and direct internet |
| Smart-home lights and switches across a house | Zigbee | Self-healing mesh, low power, many compatible devices |
| Soil moisture sensors across a farm, few readings per hour | LoRa | Kilometre range on batteries; tiny data volume |
| Water tank level 500 m away, mains power available | LoRa, or Wi-Fi with directional antennas | Depends on whether you need high data rate |
- Do not choose LoRa for audio, images or frequent updates; its data rate and airtime limits rule it out.
- Do not choose Wi-Fi for a coin-cell sensor; connection overhead drains it quickly.
- Check 2.4 GHz congestion: BLE, Wi-Fi and Zigbee all share the band, so pick Zigbee channels away from your Wi-Fi channel.
- Check local regulations for the band, power limit and any duty-cycle rules that apply where you deploy.
Summary
BLE is the low-power link to phones, Wi-Fi is the high-throughput link to the internet, Zigbee is the low-power mesh for home automation, and LoRa is the slow, long-range link for remote sensors. The differences follow directly from bandwidth and modulation: narrow, slow signals reach further on less power. Use the LoRa formula Rb = SF x (BW / 2^SF) x CR and a proper link budget to confirm your choice before you build.