Test-and-Measurement » FiRa UWB MAC Conformance Testing: Requirements & Guide

FiRa UWB MAC Conformance Testing: Requirements & Guide

uwb mac layer conformance testing fira consortium

Introduction : While physical signals carry the data, the MAC Layer manages the conversation. The FiRa Consortium MAC Conformance Test Specification verifies that a device correctly handles the complex logic of secure ranging, including Double Sided Two Way Ranging (DS-TWR), session management and dynamic security keys.

Ranging Protocol & Message Flow Tests

These tests verify that the device follows the strict sequence of messages required for Double-Sided Two-Way Ranging (DS-TWR), which is the primary method used in FiRa to cancel out clock drift errors.

Test Category	Test Item	Description/Requirement	Pass Criteria
Protocol Sequence	DS-TWR Message Exchange	Verifies the device follows the sequence: 1. Ranging Poll (Initiator) 2. Ranging Response (Responder) 3. Ranging Final (Initiator) 4. Ranging Report (Optional/Data)	The Device Under Test (DUT) must transmit the correct frame type in the correct order. If a packet is missed, the DUT must handle the retry or timeout correctly according to the spec.
Timing	Reply Time (Treply)	Measures the time gap between receiving a packet and sending the response.	The response must be sent within the negotiated time slot. If the device replies too slowly, it violates the Ranging Block timing.
Modes	Deferral and Acknowledgement	Verifies the device supports “Deferred” DS-TWR (where the data report is sent later) vs. Immediate.	Correct handling of the ACK bit in the MAC header.

MAC Frame Format Verification

FiRa v1.1.0 uses standard IEEE 802.15.4 frames but enforces specific Information Elements (IEs) and header configurations.

Test Category	Test Item	Description/Requirement	Pass Criteria
Header	MAC Header (MHR) Validation	Verifies the Frame Control Field (FCF), Sequence Number, and Addressing fields (Source/Destination PAN ID and Address).	Pass: - Correct Frame Type (Data, Control, or Ranging). - Correct Version (IEEE 802.15.4z). - Correct use of Short (16 bit) vs. Extended (64 bit) addresses.
Payload	Information Element (IE) Parsing	FiRa embeds critical data (like timestamps or application data) in Vendor Specific IEs. This test ensures the DUT correctly encodes/decodes these IEs.	The payload must contain the correct FiRa OUI, Sub-type ID, and data fields (e.g., the timestamp of the previous message).
Security	Auxiliary Security Header	Verifies that the MAC frame includes the correct security header if encryption is enabled (AES-128).	The Security Level and Key Identifier fields must match the negotiated session parameters.

Session & Ranging Management

These tests ensure the device can set up, maintain and tear down a ranging session based on parameters usually received via Out of Band (OOB) channels (like BLE).

Test Category	Test Item	Description/Requirement	Pass Criteria
Session Control	Session ID Management	Every ranging session has a unique 32-bit Session ID. The DUT must accept a Session ID and only respond to UWB packets containing that specific ID.	The DUT must ignore packets with a mismatching Session ID and respond to packets with the correct ID.
Ranging Block	Slot Scheduling	FiRa divides time into “Ranging Blocks” and “Ranging Rounds.” The DUT must transmit only in its assigned slot within the round.	No transmission outside the assigned time slot (to prevent collision).
STS Configuration	Static Vs. Dynamic STS	Verifies the MAC layer correctly configures the PHY to use the negotiated STS mode.	- Static STS: Uses a fixed key. - Dynamic STS: Rotates the key for every ranging round for maximum security.

Timestamping & Reporting Accuracy

The MAC layer is responsible for gathering the raw timestamps from the PHY and calculating the distance.

Test Category	Test Item	Description/Requirement	Pass Criteria
Calculation	Time of Flight (ToF) Report	The DUT must calculate the distance based on the 4 timestamps (Poll_TX, Poll_RX, Resp_TX, Resp_RX) exchanged during DS-TWR.	The reported distance must be within the accuracy limit (e.g., +/- 10 cm in Line of Sight conditions).
Quality Metric	Figure of Merit (FoM)	The DUT must report a confidence level (FoM) regarding the quality of the ranging measurement.	The FoM value must correlate with the actual Signal to Noise Ratio (SNR) or First Path Power level observed.

UWB MAC Layer Conformance Test Solution Providers

1. Comarch :

Product : Comarch UWB MAC Conformance Test Tool (MCTT), Versions available : MCTT 2.0, MCTT 1.0
Supports automated execution of all MAC conformance test cases such as DS-TWR flows, Security handshakes, OOB discovery etc.
Also offers Comarch Interoperability Test Tool (ITT) which is used to verify MAC/PHY interoperability against reference device.

Summary: A clean PHY signal is useless without a compliant MAC layer to direct it. The FiRa MAC Conformance Tests validate the “brain” of the UWB operation, ensuring reliable session setup and protection against security threats like distance spoofing. It also make sure that UWB products are not only interoperable but also robust enough to handle the complexities of real world secure entry and location services.