Wireless

Wireless connectivity has become a standard feature of embedded products — from simple BLE sensors to complex multi-radio IoT gateways. Choosing the right wireless protocol requires balancing range, data rate, power consumption, latency, infrastructure requirements, and regulatory considerations. Getting the protocol choice right at the start of a project avoids costly redesigns later.

What Is the Wireless Topic?

The wireless topic covers protocol selection, link budget analysis, and system-level design for products with radio connectivity. It is distinct from the RF topic, which covers the physical RF engineering (antennas, impedance matching, PCB layout). Wireless here means: how do you choose between BLE, Wi-Fi, LoRa, Zigbee, and other protocols, and what are the tradeoffs in each choice?

For the physical implementation of the wireless hardware (antenna placement, RF PCB layout, RF front-end design), see the RF topic.

Why Protocol Selection Matters

The wireless protocol is one of the most consequential early design decisions:

• Range — LoRa can reach kilometres in line-of-sight; BLE typically 10–100 m indoors.
• Data rate — Wi-Fi handles megabits per second; LoRa delivers a few hundred bits per second at maximum range.
• Power consumption — BLE in connection mode draws microamperes in sleep, milliamperes while transmitting; Wi-Fi draws tens of milliamperes in active use.
• Infrastructure dependency — LoRaWAN requires gateway infrastructure; BLE and Wi-Fi connect directly to smartphones and home routers.
• Latency — BLE offers ~7.5 ms minimum connection interval; LoRa Class A devices have up to a 2-second downlink latency window.

Key Concepts

• BLE (Bluetooth Low Energy) — short-range (typically 10–100 m), low-power protocol designed for sensor-to-phone and sensor-to-hub communication. Operates in the 2.4 GHz ISM band.
• Wi-Fi (IEEE 802.11) — infrastructure-based protocol with high data throughput and internet connectivity; higher power than BLE, typically requiring 50–200 mW while transmitting.
• LoRa / LoRaWAN — long-range, low-power, low-data-rate protocol. LoRa is the physical layer modulation (Chirp Spread Spectrum); LoRaWAN is the MAC layer and network architecture. In Australia, operates in the AU915 915 MHz sub-band.
• Zigbee / Thread / Matter — mesh networking protocols for smart home and building automation. Thread uses IPv6 natively; Matter is the application layer that runs over Thread, Wi-Fi, and Ethernet.
• ISM band — Industrial, Scientific, and Medical frequency bands where unlicensed low-power radio operation is permitted. In Australia: 915 MHz (LoRa, 915 MHz Zigbee), 2.4 GHz (BLE, Wi-Fi, Zigbee, Thread), 5 GHz (Wi-Fi).
• Link budget — the calculation that determines whether a radio link will close: TX power + TX antenna gain − free-space path loss − RX antenna gain ≥ RX sensitivity. A positive margin (in dB) means the link closes.
• Spreading factor (LoRa) — a LoRa modulation parameter (SF7–SF12) that trades data rate for range and link robustness. Higher spreading factors increase range and receiver sensitivity but reduce data rate and increase time-on-air.

Related Technologies

• Cellular (LTE-M / NB-IoT) — LPWAN protocols running on licensed cellular bands; offer nationwide coverage via existing carrier infrastructure without the gateway requirement of LoRaWAN. Higher power than LoRa but lower than Wi-Fi; suitable for applications needing wide-area coverage and willing to pay data plan costs.
• Thread / Matter — Thread is an IPv6-based mesh networking protocol for smart home devices; Matter is the application-layer standard running over Thread, Wi-Fi, and Ethernet. Relevant for products targeting the smart home ecosystem.
• UWB (Ultra-Wideband) — short-range, centimetre-level precision ranging and localisation. Used in Apple AirTags, vehicle keyless entry, and precision indoor positioning. Not a general-purpose data protocol — the use case is ranging, not throughput.
• Satellite IoT — Iridium, Swarm, Astrocast, and similar networks provide IoT connectivity in areas with no cellular or LoRaWAN coverage. Relevant for remote monitoring applications in Australia's outback.

Common Mistakes

• Choosing a protocol before defining the range and infrastructure requirements — BLE and LoRa have vastly different range capabilities and infrastructure dependencies. Define the deployment environment, range requirement, and available infrastructure before selecting a protocol.
• Underestimating Wi-Fi power consumption in battery applications — Wi-Fi typically draws 80–200 mW during active use. A BLE alternative almost always achieves better battery life for sensor-to-phone applications; Wi-Fi is appropriate when internet connectivity or high data throughput is required.
• Relying on a pre-certified module without verifying host PCB compliance — a certified module's compliance covers the module's radio emissions under the reference design conditions. The host PCB's digital emissions and power supply noise still require independent compliance assessment.
• Not verifying LoRa gateway coverage before designing a product around LoRaWAN — LoRaWAN requires gateway infrastructure. The Things Network gateway map provides Australian coverage data, but indoor penetration and rural coverage must be verified for the actual deployment site, not assumed from a network map.
• Ignoring co-existence between multiple radios on the same product — a product with both BLE (2.4 GHz) and Wi-Fi (2.4 GHz) must manage co-existence through frequency planning, timing coordination, or hardware isolation. Two radios on the same board at the same frequency degrade each other's performance if not explicitly managed.

Common Questions

What wireless protocol should I use for a battery-powered sensor?

If the sensor needs to communicate with a smartphone app, BLE is the standard choice — every smartphone supports BLE, and BLE modules consume microamperes in sleep with milliamperes during transmission. If the sensor is in a remote location beyond smartphone or Wi-Fi range, LoRaWAN offers kilometres of range with comparable power consumption, provided there is gateway infrastructure in the area. See the full protocol comparison for a complete decision framework.

Does my wireless product need ACMA certification?

Yes. Any product sold in Australia that contains an intentional radio transmitter must comply with ACMA's Radiocommunications Act framework. For products using pre-certified radio modules (RCM-marked BLE, Wi-Fi, or LoRa modules), the module's radio compliance is pre-established. The manufacturer is still responsible for ensuring the complete product — including the host PCB's non-intentional emissions — meets the applicable CISPR EMC standards. See the Compliance topic for the full regulatory picture.

How do I calculate the range of my wireless link?

Use the link budget formula: Link Margin (dB) = TX Power (dBm) + TX Antenna Gain (dBi) − Path Loss (dB) − RX Antenna Gain (dBi) − RX Sensitivity (dBm). Positive link margin means the link closes. Free-space path loss at distance d and frequency f is approximately 20·log₁₀(d) + 20·log₁₀(f) + 92.4 dB (with d in km and f in GHz). In practice, add a fade margin (typically 10–20 dB) for obstructions, multipath, and antenna non-ideal behaviour. Zeus Design designs wireless hardware and firmware for BLE, Wi-Fi, and LoRa products.

Knowledge Base

Protocol Fundamentals

• What Is Wi-Fi? — IEEE 802.11 standards, 2.4 GHz vs 5 GHz bands, CSMA/CA, WPA2/WPA3 security, and power management for IoT
• What Is Bluetooth Low Energy (BLE)? — GAP/GATT architecture, advertising, connection parameters, BLE 5.x features, and embedded module selection
• What Is Cellular IoT? — LTE-M and NB-IoT compared, PSM power saving, SIM and eSIM selection, and Australian carrier coverage
• What Is Satellite IoT Connectivity? — LEO constellations (Iridium, Swarm), store-and-forward vs real-time, antenna design, and when to choose satellite over cellular

Protocol Comparison and Selection

• Bluetooth vs Wi-Fi vs LoRa vs Zigbee: Which Protocol Should You Use? — the complete side-by-side comparison: range, data rate, power, infrastructure, latency, and Australian use cases
• What Is LoRa and LoRaWAN? — LoRa modulation, spreading factors, LoRaWAN architecture, and the AU915 frequency plan

LoRa & LoRaWAN Setup

• Connecting a LoRaWAN Device to The Things Network in Australia — AU915 sub-band 2 channel configuration, OTAA device registration on TTN, LMIC and RadioLib firmware setup, and first-join verification
• How Do You Design the Hardware Around an SX1262 or SX1276? — IC-specific hardware design guide: power supply decoupling, 32 MHz crystal and load capacitor selection, impedance-matching π-network, and 50 Ω RF trace routing for AU915

Antenna and RF Implementation

For selecting and placing antennas, and laying out the RF section of the PCB, see:

• What Antenna Types Are Used in Embedded Wireless Designs? — chip, PCB trace, and external antenna types for BLE, Wi-Fi, and LoRa products
• How Should You Lay Out the RF Section of a PCB? — antenna keepout zones, 50 Ω trace routing, and ground plane design

Regulatory Compliance for Wireless Products

For Australian ACMA compliance requirements for radio transmitters, see the Compliance topic.