RSDB – Connecting cars with better WiFi

The increasing use of WiFi in our cars as hotspots and smartphone connections is without a doubt a great convenience, but can also create radio interference issues. Car environments are extremely noisy. In‑car WiFi signals have to compete with in‑car interference from Bluetooth devices, as well as interference from WiFi hotspots and other miscellaneous ISM band noise in the vicinity.

This interference ends up lowering WiFi transmission speeds or even disrupting connections for both WiFi and Bluetooth devices.

Dual band isn’t enough
While Bluetooth, cordless phones and countless other wireless devices use the noisy 2.4GHz band present in most car hotspots, the WiFi band 802.11ac has the ability to operate on the less congested  5GHz band which is not only less used, but offers more channels for communication.

Most automotive‑grade WiFi chipsets today achieve concurrent operation in the 2.4GHz and 5GHz band using a technique called ‘time‑division‑multiplexing’, resulting in lower data rates per band.

Since many older WiFi devices only work on the 2.4GHz band, car hotspots are required to stick to this band for compatibility reasons. As the 2.4GHz is also used by Bluetooth and other WiFi devices leading to congestions, transmission speeds can be less than suitable.

Next‑gen applications, such as a WiFi Screen via Apple Car Play or a Rear Seat Infotainment System, try to avoid congestion and mediocre quality of service by resorting to the 5GHz band – resulting in a dual‑band requirement.

Real simultaneous dual band
Now, a new type of WiFi module capable of transmitting on both 2.4GHz and 5GHz bands simultaneously is available, and greatly improves the situation.

Real Simultaneous Dual Band (RSDB) WiFi modules can support two separate WiFi networks, one on the 2.4GHz band and another on 5GHz.

For the in‑car environment, this allows for high data rates and robust WiFi signals on the 5GHz band, while still supporting legacy devices on 2.4GHz at optimal speeds.

Since 5GHz WiFi is faster and more reliable, high priority WiFi traffic can utilise this band and the 2.4GHz band can be used for general WiFi traffic.

The ‘magic’ of real simultaneous dual band is that the 2.4GHz and 5GHz WiFi networks operate simultaneously, and fully independently of each other, optimising performance on each network. For instance, 5GHz could be used to drive vehicle communication needs such as rear‑seat entertainment or a smartphone infotainment connection (Apple CarPlay in fact uses and requires a 5GHz WiFi connection), while the car’s WiFi hotspot operates over 2.4GHz. This allows the car to support legacy WiFi devices with Internet connectivity while also providing fast, clean and reliable 5GHz WiFi connections for the internal vehicle systems that need it most.  

Implementing RSDB with JODY‑W1
RSDB technology is incorporated into the latest WiFi+Bluetooth module, JODY‑W1 from u‑blox. Thanks to Real simultaneous dual band, JODY‑W1 lets car makers provide fast, noise‑free traffic on the 5GHz band for high‑priority services like smartphone to infotainment system connections or Head Unit to Rear‑Seat‑Entertaiment displays, while serving regular WiFi traffic on the 2.4GHz band.

By segregating traffic across different bands, JODY‑W1 allows for better, more reliable WiFi communication.

Guest blog by Kilian Frank, Product Strategy, Product Center Short Range Radio, u-blox.

Courtesy of u-blox.