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Foundations for Software Defined Vehicles - FOTA, SOTA Solutions

Dec 21, 2022      View: 375

OTA (Over-the-Air Technology) is a technology that remotely manages data and applications of remote devices through the air interface of mobile communication networks

Foundations for Software Defined Vehicles - FOTA, SOTA Solutions

What is OTA?

OTA (Over-the-Air Technology) is a technology that remotely manages data and applications of remote devices through the air interface of mobile communication networks.

OTA can be broadly divided into two categories: FOTA (Firmware-over-the-air): Which means downloading a complete firmware image to a device, ECU flash memory, or patching existing firmware or updating flash memory. For example, it can upgrade our vehicle's steering system to make driving easier, upgrade the gas pedal response to make acceleration more linear and comfortable, etc. In short, compared to SOTA, FOTA technology has a higher gold content.

SOTA (Software-over-the-air): Those applications and maps that seem closer to the user OTA belong to the SOTA category. For example, when we upgrade the multimedia system to replace the operating interface or theme or even change the dashboard display style, we use this SOTA upgrade method, which is also the main way to upgrade our brand cars OTA today.

The value of OTA

Carriers and wireless terminal manufacturers see FOTA as a valuable capability to avoid device recalls, reduce customer service calls, and lower operational execution costs. The average cost of a recall triggered by software and firmware defects is between $50 - $100 per device. Often, carriers and OEMs negotiate recall costs, which can sometimes spike into the millions of dollars per case. In addition, defects in mobile software applications can directly impact the brand image of device manufacturers and mobile carriers. FOTA allows carriers to bring the latest wireless devices to market promptly while avoiding device recalls, brand damage, and loss of personal consumer data.

Fixing Defects

As the complexity of automotive functional applications increases, so does the potential for software defects. In addition, time-to-market is extremely important for automobiles. In many countries, Tier 1 operators launch their devices on a regular annual basis. These factors increase the probability that device integrity will not be at the highest level at the time of launch significantly. When an operator identifies an emergency-level defect, the OEM needs to provide a solution as soon as possible and create a tested version of the firmware fix distributed wirelessly by the operator to affected users. Low-level defects can accumulate into a major update with new features and performance improvements. 

New Features

Many new features and applications can be obtained and activated when a device becomes available via firmware over-the-air updates. Many leading manufacturers and carriers worldwide push this service to consumers after they purchase a mobile device. Consumers can also regularly check for new firmware/software updates and install and update them regularly. 

Optimize performance

The performance of mobile devices is one of the key parameters that affect the consumer user experience. Battery life, throughput, and responsiveness significantly impact a device's success in the marketplace. In some cases, devices are shipped with less than fully optimized performance, and only updated versions are subsequently available over the air. 

Broad uses of OTA

Smart Cars

OEM vehicle upgrades, front-mounted Tire1 device upgrade builds, rear-mounted in-vehicle smart products

Smart Wear

Smartwatches/health monitoring

Smart Home

Smart home appliances, smart gateway, monitoring/security, the cleaning robot

Industry Applications

Industry custom handheld terminal, advertising machine, charging pile, electric bicycle, industrial man-machine surface


2G/3G/4G module, Wifi module Lora module, NB-IOT module

What are the functional requirements of FOTA solutions?

  • 100% reliability - The update process is not affected even in a device power outage or network communication failure.
  • Enhanced security - The security mechanisms in the FOTA solution ensure the integrity of the FOTA process. - Client-independent solution - the client is not tied to the server; the FOTA software on the device can work with any management server
  • Enhanced consumer experience - The FOTA solution provides consumers with information throughout the update process, such as progress bars or predefined messages. - Differential package size - update packages have been proven to be the smallest, saving both network bandwidth and download time.

Automotive OTA Difficulties and Key Technologies

Ensuring Security

There are three segments to consider for OTA security: the first segment is the security on the server side of the cloud, the second segment is the security on the vehicle side, and the other is the communication between the vehicle and the cloud. These three segments use not only authentication but also Encryption. To illustrate the image: "Encryption is to keep others from seeing what I am transmitting. Authentication ensures that the vehicle side, the cloud side is the one I expect and recognize." For example, when the vehicle does a software upgrade, it sends an authentication request to the server; after the server receives the request information from the vehicle side, it sends feedback and asks to send a digital certificate to self-identify. The car end sends the digital certificate to the server; the server checks the digital certificate for problems; the terminal management system sends the verification result to the terminal after the verification is correct, and the corresponding software upgrade can be started. The update package will be encrypted and transmitted to the vehicle side, decrypted in T-box, and then distributed to the vehicle. One of the reasons why FOTA is more challenging than SOTA is that the flash memory of the integrated firmware update installer is small, and the FOTA update package and the update software have to be installed in the small memory of the vehicle's embedded device. Therefore, the update package is compressed as much as possible, typically 5% of the original size.

Transfer Efficiency 

To ensure efficiency, we technically use differential updates, i.e., we compare the differences between the old and the new version and generate a differential file. When the difference between the old and the new file is not particularly large, only the difference file can be transferred. The core technology of differential update is the byte differential algorithm mastered by each supplier. For example, Redland (an Israeli software provider acquired by Harman in 2015), which provides OTA technology for Tesla, has a technology that fragments update packets into multiple small data stream files and distributes them in a network with limited bandwidth so that devices can obtain multiple short files and update them at the same time, mainly addressing the performance limitations of miniature electronic devices such as miniature ECUs and M2M modules in cars. The problem of performance limitations exists. For example, car updates must not affect the safety of the vehicle. The car's environment may change a lot, for example, into a tunnel, underground garage, or these places without a signal. When there is an abnormality, the electronic parts of the vehicle end need to be able to cope with different external environments, good protection, and complete self-recovery when the upgrade fails.

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