A collision detection method based on power sensing and time-domain signal processing for wireless LAN

Abstract

Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) access control protocol is used in the wireless LAN (WLAN) to suppress interferences. According to the CSMA/CA, if the transmitter does not receive an acknowledgment (ACK) control frame from the receiver after transmission, it will assume the previous transmission has failed and repeat the transmission. In order to evaluate the transmission channel and optimize the transmission parameters for improving the efficiency of data transmission it is necessary to distinguish the reason for transmission failure — collisions or attenuation in the transmission channel. Some enhanced collision detection methods for IEEE 802.11 WLAN have been proposed. In these schemes, the exchange of detection information is necessary, which could lead to additional collisions. So the detection information itself might not be received correctly due to collisions. In this paper, we propose a novel collision detection method, based on signal power sensing and time-domain signal processing, for transmitting stations in WLAN, which does not require the feedback of information from the receiver. With the calculation of collision frequency, the transmission parameters can be adjusted to improve the efficiency of data transmission. The effectiveness of the proposed collision detection method is verified in an experiment.