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CAN/CSA-ISO/IEC 15149-4-18: Protocol Specifications for Magnetic Field Area Network Wireless Power Transfer and Communication
A Comprehensive Technical Guide to the International Standard for Combined Wireless Power and Data Transmission Using Magnetic Field Coupling
Scope and Applications
The CAN/CSA-ISO/IEC 15149-4-18 standard (identical to ISO/IEC 15149-4:2018) specifies the protocol for wireless power transfer (WPT) and simultaneous data communication in a Magnetic Field Area Network (MFAN). This standard is part of the ISO/IEC 15149 series, which defines the air interface, network layer, and application layer for MFAN systems operating in the low-frequency ISM band around 6.78 MHz.
The primary scope of Part 4 is to establish a unified protocol that enables devices to negotiate power transfer parameters, manage communication sessions, and ensure safe and efficient operation. Key application areas include contactless charging of portable electronics, industrial sensors, medical devices, and Internet-of-Things (IoT) nodes where both power and data must be exchanged over a short range (typically up to a few meters) using magnetic field coupling.
Technical Requirements and Protocol Architecture
Protocol Stack Overview
The standard defines a layered protocol stack consisting of a Physical Layer (PHY), Data Link Layer (DLL), Network Layer (NWK), and Application Layer (APL). Each layer provides specific services for power transfer control and data communication. The following table summarizes the main functions and key parameters at each layer:
| Layer | Primary Functions | Key Parameters |
|---|---|---|
| Physical (PHY) | Modulation/demodulation, frequency generation, RF front‑end control | Carrier: 6.78 MHz ± 15 kHz; Data rates: 4.8 kbps to 1.2 Mbps; Modulation: OOK, FSK, BPSK |
| Data Link (DLL) | Frame formatting, error detection (CRC), medium access (TDMA/CSMA), retransmission | Frame length: up to 255 bytes; MAC modes: beacon‑enabled (tree/star topology); Slotted CSMA/CA |
| Network (NWK) | Routing, addressing, device discovery, power control negotiation | Short address (16‑bit); PAN ID; Mesh routing; Power request/grant frames |
| Application (APL) | Power transfer profiles, data streaming, security (AES‑128), device configuration | Profiles: Basic Charging, Dynamic Power, Data Exchange; Security: CCM* |
Wireless Power Transfer Protocol
The core of Part 4 is the power transfer protocol, which defines the handshake between a power source (charger) and a receiving device (load). The protocol supports two operational modes:
- Synchronous mode – Power is delivered in scheduled time slots coordinated by a central coordinator (typically the charger). Data can be interleaved with power transfer using time-division duplex.
- Asynchronous mode – Power is transferred continuously while data packets are exchanged on a separate logical channel using frequency or code division multiplexing. The standard specifies a maximum transmitted power of 30 W (for consumer applications) and up to 100 W for industrial equipment under defined safe operating conditions.
To guarantee coexistence with other wireless systems operating in the same ISM band, the standard mandates a transmit spectrum mask and a receiver selectivity template. Devices must implement adaptive power control (APC) to adjust the radiated power based on received signal strength and link quality.
Implementation Considerations
Tip: For optimal performance in applications such as wireless charging of medical implants, designers should prioritize a high‑Q coil design and carefully tune the resonance matching network to the 6.78 MHz carrier frequency. The protocol’s synchronous mode can be used to minimize interference with sensitive electronics.
When implementing a CAN/CSA-ISO/IEC 15149-4-18 compliant device, developers must pay close attention to the following:
- Coil Antenna Design – The magnetic field coupling efficiency depends on the geometry, number of turns, and material of the coils. The standard provides reference guidelines for antenna impedance and Q‑factor (target Q > 30 at 6.78 MHz).
- Medium Access Control – For networks with multiple power receivers, the coordinator must manage the time slots and control frames (beacons) to avoid collisions. The DLL supports up to 256 devices per PAN.
- Power Negotiation – The charging device must request a power class (0‑3) and the source responds with a power grant specifying maximum current and voltage limits. The protocol allows dynamic adjustments during operation to handle load changes.
- Security – All data and control frames can be encrypted using AES‑128 in CCM* mode. The standard defines a key establishment procedure based on a passkey entry or out‑of‑band exchange.
Important: Testing has shown that unshielded coils can cause electromagnetic interference with nearby RFID readers and NFC systems operating at 13.56 MHz. Careful filtering and shielding are recommended to preserve coexistence.
Compliance and Certification
Compliance with CAN/CSA-ISO/IEC 15149-4-18 is critical for devices that claim interoperability with other MFAN‑based wireless power systems. The standard is adopted by the Canadian Standards Association (CSA) and is harmonized with the international version ISO/IEC 15149-4:2018. Certification typically involves the following steps:
- Conformance Testing – Verification that the protocol implementation correctly handles all mandatory commands, frame formats, and error conditions as specified in the protocol definition. The test suite includes up to 200 test cases for the PHY and DLL layers.
- Interoperability Testing – Validation that the device can successfully pair and exchange power/data with a reference implementation (e.g., a certified charger and load).
- Radio Parameter Measurement – Measurement of transmit power, frequency tolerance, occupied bandwidth, and spurious emissions to ensure compliance with regional regulations (e.g., ICES‑001 in Canada, FCC Part 15 in the USA).
- Safety Assessment – Evaluation of specific absorption rate (SAR) for human exposure and temperature rise under maximum power transfer conditions. The standard references IEC 62368‑1 for safety of electrical equipment.
Success: Products that achieve CAN/CSA-ISO/IEC 15149-4-18 certification benefit from a clear competitive advantage, as they can confidently claim compatibility with the growing ecosystem of MFAN‑enabled chargers and smart devices.
Warning: Non‑compliant implementations may not only fail interoperability but can also risk violating regulatory emission limits. Always verify that the power control algorithm and modulation scheme exactly match the standard’s specifications before mass production.
Frequently Asked Questions
Q: What is the main difference between ISO/IEC 15149-4 and other wireless power standards such as Qi or AirFuel?
A: ISO/IEC 15149‑4 is specifically designed for combined wireless power transfer and data communication over a magnetic field area network. While Qi and AirFuel focus primarily on charging with basic communication, the MFAN protocol provides a full network stack (PHY, MAC, NWK, APL) supporting mesh networking, encryption, and streaming data services, making it suitable for IoT and industrial applications.
A: ISO/IEC 15149‑4 is specifically designed for combined wireless power transfer and data communication over a magnetic field area network. While Qi and AirFuel focus primarily on charging with basic communication, the MFAN protocol provides a full network stack (PHY, MAC, NWK, APL) supporting mesh networking, encryption, and streaming data services, making it suitable for IoT and industrial applications.
Q: Which frequency bands are used in this standard?
A: The standard mandates the 6.78 MHz ISM band (6.765–6.795 MHz) as the primary carrier. Some national variants may also use 13.56 MHz with a different PHY specification, but CAN/CSA‑ISO/IEC 15149‑4‑18 is defined for 6.78 MHz operation.
A: The standard mandates the 6.78 MHz ISM band (6.765–6.795 MHz) as the primary carrier. Some national variants may also use 13.56 MHz with a different PHY specification, but CAN/CSA‑ISO/IEC 15149‑4‑18 is defined for 6.78 MHz operation.
Q: Is the protocol backward‑compatible with earlier parts of the ISO/IEC 15149 series?
A: Yes. Part 4 builds on the PHY and MAC defined in Parts 1 and 2. Devices implementing Part 4 can operate in a mixed network, but they must support the power‑negotiation frames introduced in Part 4. Backward compatibility is ensured through the use of standard beacon frames and device capability discovery.
A: Yes. Part 4 builds on the PHY and MAC defined in Parts 1 and 2. Devices implementing Part 4 can operate in a mixed network, but they must support the power‑negotiation frames introduced in Part 4. Backward compatibility is ensured through the use of standard beacon frames and device capability discovery.
Q: What are the typical data rates achievable under the standard?
A: Depending on the modulation and coding scheme, raw data rates range from 4.8 kbps (with robust FSK) up to 1.2 Mbps (using BPSK with high‑rate channel coding). In typical wireless charging scenarios, the protocol allocates about 20% of the channel capacity to data, while the remainder is used for power transfer signaling and control.
A: Depending on the modulation and coding scheme, raw data rates range from 4.8 kbps (with robust FSK) up to 1.2 Mbps (using BPSK with high‑rate channel coding). In typical wireless charging scenarios, the protocol allocates about 20% of the channel capacity to data, while the remainder is used for power transfer signaling and control.
Article prepared for technical reference. Last update: 2026.