Broadcast packet collision and avoidance method in Wi-Fi based broadcasting system

In this paper, we present a collision avoidance method for Multi-AP Wi-Fi broadcasting systems. Whereas the existing studies consider single AP based Wi-Fi broadcasting systems, our study focuses on Multi-AP systems which can cover much wider area. We identify and describe a packet collision problem, specific to Multi-AP systems, caused by simultaneous transmission. Two collision scenarios are found according to the state of the medium at the time of packet arrival. We propose two methods to handle each scenario: the broadcast packet scheduling method and the adaptive contention window sizing method. We implemented both methods in our Wi-Fi broadcasting system and experimentally verified the effectiveness of the collision avoidance.