Wi-Fi

Wi-Fi, also known as a Wireless Local Area Network (WLAN), is a wireless communication technology based on the IEEE 802.11 series of standards. Within the Vehicle-to-Everything (V2X) ecosystem, Wi-Fi operates primarily across two domains: in-cabin local area networks and short-range external connectivity. It allows vehicles to exchange high-speed data with passengers’ mobile devices, roadside infrastructure, and surrounding vehicles, serving as an indispensable supplementary technology for in-car infotainment and targeted external communication scenarios.

Technical Principles and Core Standards

Wi-Fi technology utilises the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol, enabling multiple devices to share the same wireless channel. Its core operating frequency bands are 2.4 GHz and 5 GHz, with the latest Wi-Fi 6E and Wi-Fi 7 standards expanding support to the 6 GHz spectrum.

The standardisation of Wi-Fi is overseen by the IEEE (Institute of Electrical and Electronics Engineers). In automotive applications, the key evolutions across standards include:

• IEEE 802.11b/g/n (Wi-Fi 4): Operates on the 2.4 GHz band, providing baseline network connectivity.

• IEEE 802.11a/ac (Wi-Fi 5): Operates on the 5 GHz band, offering higher throughput for HD video streaming across in-car entertainment systems.

• IEEE 802.11ax (Wi-Fi 6/6E): Introduces OFDMA and TWT technologies to substantially enhance network efficiency and stability under multi-device concurrency; it currently serves as the benchmark standard in premium smart cockpits.

• IEEE 802.11be (Wi-Fi 7): Incorporates ultra-wide 320 MHz channels and Multi-Link Operation (MLO) aggregation technology, drastically elevating throughput while minimising latency. This establishes the foundation for high-bandwidth cabin applications such as in-car AR/VR and multi-screen HD interactivity. Flagship smartphones equipped with Wi-Fi 7 chipsets have already begun real-world vehicle integration trials, with series-production Wi-Fi 7 models expected to roll out from 2026 or 2027 onwards.

Note: The Wi-Fi technical standard (IEEE 802.11) framework is extensive. Beyond the general standards mentioned above, dedicated branches have been tailored for specific use cases. Notably, IEEE 802.11p is a specialised standard engineered specifically for high-speed vehicular mobility environments. It serves as the physical layer foundation for Dedicated Short-Range Communications (DSRC) under the V2X umbrella, differing fundamentally in principle and application from commercial Wi-Fi.

Key Applications in the Internet of Vehicles

In-Cabin Communication (Infotainment and Connectivity)

This represents the most widespread automotive application of Wi-Fi. Through a built-in in-car Wi-Fi hotspot (tethering), the vehicle harnesses its onboard 4G/5G cellular connectivity to supply high-speed internet to passengers’ smartphones, tablets, and laptops. The high bandwidth and ultra-low latency of Wi-Fi 6/7 effortlessly support multi-screen HD video streaming, online gaming, and wireless screen mirroring—turning the cabin into a mobile entertainment hub.

Direct V2X Communication (Supplementary & Auxiliary)

Within the Vehicle-to-Everything (V2X) framework, while C-V2X and DSRC (802.11p-based) remain the dominant vehicle-to-vehicle and vehicle-to-infrastructure technologies, certain architectures employ peer-to-peer (P2P) modes of standard Wi-Fi (such as Wi-Fi Direct) as a complementary channel:

• Vehicle-to-Infrastructure (V2I): In designated environments (such as carparks or highway service areas), vehicles can link with Roadside Units (RSUs) via Wi-Fi to download high-definition map data or execute bulk data synchronisation.

• Vehicle-to-Vehicle (V2V): Under low-speed or stationary conditions, vehicles can share files or engage in local multiplayer gaming via Wi-Fi Direct.

OTA Updates and Diagnostics (Contingency Solution)

Although Over-the-Air (OTA) updates are primarily deployed via cellular networks (V2N), Wi-Fi serves as a dependable secondary channel. In areas with weak cellular coverage (such as basement car parks), selected carmakers (such as Tesla) allow vehicles to connect to trusted Wi-Fi networks to download substantial OTA firmware updates—providing a stable, high-throughput synchronisation method.

Challenges and Limitations

Despite its maturity in cabin applications, Wi-Fi exhibits clear limitations when applied to external V2X communication:

• Limited Coverage Range: Commercial Wi-Fi was fundamentally engineered for indoor local networking, with transmission ranges typically restricted to within 100 metres and heavily compromised by physical obstacles. Consequently, it falls short of meeting the multi-hundred-metre range and millisecond-level latency demands required for high-speed V2V and V2I scenarios.

• Security Discrepancies: Commercial Wi-Fi relies on protocols such as WPA2/WPA3. These authentication frameworks differ considerably from the low-latency broadcast security and certificate management systems mandated in V2X applications, presenting potential cybersecurity vulnerabilities.

• High-Speed Mobility Constraints: Standard Wi-Fi specifications (such as 802.11ac/ax) are not optimised for high-speed mobility (e.g. speeds exceeding 120 km/h), experiencing substantial performance degradation caused by Doppler shifts and frequent handovers.

Crucial Takeaway: In safety-critical V2X communication within connected vehicles, standard Wi-Fi functions solely as a supplementary or failover mechanism. Time-sensitive, mission-critical applications (such as forward collision warning and autonomous emergency braking) must strictly rely on dedicated protocols like C-V2X or DSRC. Standard Wi-Fi should not be utilised as the primary medium for V2X communications.