With the rapid development of the low-altitude economy

the high-density operation of aircraft has imposed stringent requirements on collision avoidance capabilities. Aiming at the communication requirements for low-altitude collaborative collision avoidance

this paper proposes a system architecture based on Cellular-Vehicle-to-Everything (C-V2X) Proximity-services Communication 5 (PC5) sidelink communication

which consists of the sidelink communication interaction layer

the wide-area communication management layer

and the on-board fusion execution layer. Typical low-altitude scenarios and corresponding communication performance requirements are analyzed. The core enabling technologies and the standardized collaborative collision avoidance interaction process are elaborated. Finally

future research directions such as 3D beam management

intelligent interference coordination

and spectrum policy are discussed

providing a theoretical reference for the construction of low-altitude safety communication systems.