GMSL in ADAS: High-speed data transmission in vehicles

Gigabit Multimedia Serial Link (GMSL) How precise tests secure the future of driver assistance systems

2025-02-11 The conversation was conducted by | Translated by AI 3 min Reading Time

Related Vendors

Keysight Technologies Deutschland GmbH

FAULHABER Drive Systems

dataTec AG

Wuxi InfiMotion Technology Co., Ltd.

GMSL ensures high-speed data transmission and is a central component of ADAS in vehicles. To ensure performance, extensive testing is necessary. Additionally, new legal requirements for ADAS increase the pressure on developers and manufacturers.

GMSL ensures high-speed data transmission and is a central component of ADAS in vehicles. Extensive testing is intended to guarantee performance.(Image: Keysight) — GMSL ensures high-speed data transmission and is a central component of ADAS in vehicles. Extensive testing is intended to guarantee performance.
(Image: Keysight)

High-speed data transmissions are an essential component of modern Advanced Driver Assistance Systems (ADAS). Gigabit Multimedia Serial Link (GMSL) plays a central role by efficiently transmitting high-resolution sensor data. With new EU regulations, which have made certain ADAS functions mandatory in new vehicles since July 2024, the importance of standardized and reliable testing methods is increasing. But how can the quality and compliance of this technology be ensured?

Paul Fernando, Director, Ecosystem Strategy of Automotive Business Unit at ADI, and Carrie Browen, Software-Defined Vehicle Business Line Product Manager at Keysight, report on test details and how new standards can be established.

What requirements does GMSL place on testing methodology to support ADAS systems?

As with other high-speed transmission technologies, GMSL requires a detailed examination of the Physical Medium Attachment (PMA). These tests are essential to ensure the performance and reliability of components that contribute to increased driving safety. The technical background lies in signal transmission over different physical media, where signal distortion, attenuation, and electromagnetic interference can occur.

A precise characterization of the PMA allows for the optimization of driver and receiver parameters to ensure robust and interference-free transmission. Targeted tests enable developers and manufacturers to identify and address potential weaknesses at an early stage.

What tests are required for the compliance and validation of GMSL2?

Keysight tests forward and reverse transmission eye masks and narrowband noise to check the quality of serializer/deserializer signals. In addition, narrowband noise measurements are conducted to identify possible signal distortions. Cable validation focuses on insertion and return loss as well as cable crosstalk, which can cause potential interference in the transmission path. Furthermore, the MDI head is analyzed for its insertion and return loss to minimize signal losses at interfaces. Finally, multilink interferences are examined to assess the extent to which parallel transmission paths influence each other and thereby affect system performance.

GMSL2 is an advancement and offers higher bandwidths, improved signal integrity, and greater flexibility in system architecture compared to its predecessor. This enables more efficient integration of modern sensors and cameras in ADAS systems.

How can bandwidth for high-resolution camera and radar systems in ADAS be efficiently provided?

High data rate protocols rely on a combination of NRZ (Non-Return-to-Zero) and PAM4 (Pulse Amplitude Modulation) to meet the requirements for channel length and data throughput. Transmitter jitter and linearity are critical parameters for assessing signal quality, as they directly affect transmission stability.

To ensure that electromagnetic compatibility (EMC) requirements in the vehicle are met, PSD tests (Power Spectral Density) are required to analyze the spectrum of emitted signals. Limiting jitter helps stabilize the received signal at the downstream component and minimize errors.

Modern digital architectures also rely on advanced signal processing techniques, including filtering, equalization, and error correction methods such as Reed-Solomon Forward Error Correction (RS-FEC), to ensure robust communication. Since receivers must process heavily attenuated signals that travel over lossy channels, system validation also requires analyzing the Bit Error Rate (BER) under real interference conditions to assess resilience to disturbances within the vehicle.

How can new standards be implemented most quickly to maintain a leading role?

The choice of the electrical and electronic (E/E) architecture depends on the respective application requirements. Vehicle manufacturers must consider several aspects, including the complexity and weight of the wiring harness, to ensure an optimized vehicle architecture. The reusability of sensor data also plays a central role, as it can be used for various ADAS functions. Additionally, long-term interoperability between Tier-1 suppliers and OEMs is crucial to ensure that components remain compatible throughout the entire vehicle lifecycle.

An open, standardized communication infrastructure offers clear advantages over proprietary solutions. SerDes (Serializer/Deserializer) and Automotive Ethernet are key technologies to enable seamless integration. Collaboration between OEMs, chip manufacturers, and test providers in implementing unified test methods ensures that new standards reach the market faster and become established. (heh)

Gigabit Multimedia Serial Link and Gigabit Ethernet are two popular techniques for connecting cameras, which are frequently found in various end markets, such as automotive. (Image:BMW)

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