80211p

IEEE 802.11p, also known as Wireless Access in Vehicular Environments (WAVE), is an amendment to the IEEE 802.11 family designed to enable wireless communication for vehicles and roadside infrastructure in high mobility scenarios. It operates in the 5.9 GHz ITS spectrum and is widely associated with DSRC in the United States and ITS-G5 in Europe. The physical (PHY) layer and medium access control (MAC) layer are derived from 802.11a but adapted for vehicular use, notably by using 10 MHz channels and a shortened OFDM symbol, to improve range and robustness in fast-moving environments. It supports ad hoc V2V and V2I communications and does not require access points.

A key feature is the multi-channel operation defined in IEEE 1609.4, with a control channel (CCH) for safety-related messages and service channels (SCH) for non-safety data. Applications commonly include Cooperative Awareness Messages (CAMs) and Decentralized Environmental Notification Messages (DENMs). The technology is designed for low-latency, high-reliability communications and prioritizes safety messages via QoS mechanisms.

Security and privacy are addressed through the IEEE 1609.2 framework, which specifies digital certificates and message signing to ensure authenticity while preserving user privacy through pseudonyms. The standard is commonly deployed as part of ITS stacks (IEEE 1609.x) and is considered the basis for V2X communications in many regions, though newer approaches such as IEEE 802.11bd and cellular V2X have emerged as alternatives.