This problem of concurrency extends beyond the provision of Wi-Fi connectivity to include 2.4GHz Bluetooth connections as well. In the scenario outlined above, a second passenger may be conducting a voice call over a Bluetooth audio link. In fact, the Bluetooth radio is active even when no device is paired to it. A Bluetooth host continually advertises itself, broadcasting an ‘I’m available’ message to devices in range. Different manufacturers implement Bluetooth advertising in different ways. Reducing the advertising duty cycle saves power, but risks extending the time before a Bluetooth end user device is recognised by the host and paired.
Many car manufacturers maintain a 100% Bluetooth advertising cycle for the best user experience, but this has the effect of saturating the 2.4GHz band and greatly limiting the use of 2.4GHz Wi-Fi if shared on the same antenna. In the CYW89359, the Bluetooth radio has its own dedicated RF path and antenna, enabling the host’s advertising broadcasts to be transmitted via one antenna while the 2.4GHz and 5GHz Wi-Fi radios operate via separate antennas. This provides for concurrent Bluetooth and Wi-Fi operation without interruption.
Securing the internet interface
By installing a Wi-Fi radio into cars, manufacturers provide a communications channel capable of carrying large over-the-air software updates – a valuable new feature both for the manufacturer and for the user of the vehicle. But this capability also exposes the vehicle to the risk of harm from malicious attack, in the same way that networked personal computers are vulnerable.