How real simultaneous dual band Wi-Fi enables next-generation in-vehicle connectivity


July 03, 2018

jsbaerSachin.Gupta_0623,-July 03, 2018

Remember the days when GPS did not exist and maps were the essential tool for navigation? Back then, the only source of in-car entertainment was AM/FM radio or physical media like cassettes and CDs. This was a time when cars were primarily differentiated by their drivability. Then came the era when Bluetooth began to be integrated into vehicles to for hands-free calling and basic music streaming, and car buyers because focusing more on in-car functionality when making purchase decisions.

Today, many vehicles offer at least this level of in-car connectivity. However, the rising number of cell phones, tablets, and other smart devices has increased the average consumer’s technological awareness. As a consequence, their expectations are stretching the limits of in-car connectivity requirements.

Infotainment systems have now become a key differentiating factor in automobiles. These systems are highly complex and powerful, including both driver-assist systems as well as entertainment support for the driver and passengers. Cars are being equipped with rear seat high-definition displays for video. Apps like Apple CarPlay and Android Auto allow each user’s phone to be seamlessly connected to the vehicle’s infotainment system.

As all of these devices are connecting wirelessly in the constrained environment of a vehicle, the available RF spectrum must be used efficiently to maximum possible usage with available wireless technologies. In this article, we will explore in-car connectivity use cases, their technical requirements, and how these can be addressed effectively to provide the best in-car experience.

Infotainment system features are advantages

The following are a few of the use-cases/features of an infotainment system that are either available in today’s cars or being introduced in upcoming vehicles, as well as their advantages:

  • Hands-free calling – This feature allows user to attend or make calls using controls available on the steering wheel without touching the phone. This feature not only makes it easy to access the phone’s calling function, it also makes driving safer as a user does not need to handle the phone physically.

  • Ability to read text messages – This feature allows users to read text messages on an infotainment system’s screen using the controls available on the steering wheel without the need for touching the phone. Similar to hands-free calling, this feature also makes driving safer as users do not need to physically access the phone to read a text message. Text-to-voice is often combined with this capability to provide a distraction-free experience.

  • Audio-synchronization to play music – This feature allows a user to synchronize a phone’s audio with the infotainment system. Using this feature, music on a phone can be enjoyed over in-car speakers and can be controlled using various buttons available on the steering wheel or the dashboard controls. With wireless audio synchronization, there is no need to connect an axillary cable to the infotainment system and music can be controlled by any passenger.

  • Support for new apps like Apple CarPlay and Android Auto – A car that supports these apps allows the phone’s display to be replicated on the dashboard LCD display, providing easy access to various phone features and commonly used applications like maps, music etc. For example, with support of these apps, navigation can be displayed on the dashboard display, or a YouTube video can be played solely using dashboard touch screen. This feature not only allows access to the phone, it also provides an alternative to generally complicated infotainment system user interfaces, by allowing the user to retain their familiar smartphone interface.

  • Video streaming to rear seat displays – This feature allows video streaming to rear seat high-definition display using a car’s LTE modem or a local media device, or through the smartphone’s Wi-Fi hotspot. It can be used by children or by passengers who do not need to concentrate on the road.

  • Internet access through a car’s built-in LTE modem – This feature allows passengers to access the Internet on phones, tables or laptops using the car’s built-in LTE modem.

Wireless technology needed by infotainment features

Figure 1 shows a high-level block diagram of in-car connectivity. The actual implementation varies on the system architecture. Also, this diagram does not capture use cases that may extend to body electronics (although wireless connectivity is becoming increasingly popular for these use cases as well).

Figure 1: Connectivity with infotainment/telematics system (Source: Cypress)

Bluetooth - Bluetooth in vehicles is been around for more than a decade. Features like hands-free calling, reading text message and audio synchronization features use Bluetooth.

Wi-Fi – Features like rear seat video streaming and Internet access through a car’s built-in LTE modem use Wi-Fi. Apple CarPlay and Android Auto applications started with wired connectivity to the infotainment system but are now moving to wireless and use Wi-Fi for over-the-air connectivity.

Almost all of these features need to be available simultaneously. For instance, when the driver is on a call, maps must be displayed at the same time and rear-seat entertainment must not be interrupted. However, it is important to understand the constraints imposed by limited spectrum available for over-the-air communication. Bluetooth uses 2.4 GHz ISM band for communications as do most Wi-Fi devices. Until IEEE 802.11n, Wi-Fi used 2.4 GHz band for communication. Both Bluetooth and Wi-Fi operating in the 2.4 GHz band without coordinated coexistence measures in place can result in choppy audio and severely impacted Wi-Fi throughput.

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