Comparison of WiFi-compliant techniques for delay-sensitive wireless monitoring

Based on a real industrial case, we present a study on the application of WiFi to a delay-critical automation scenario. The primary purpose of the study was the identification of standard-compliant techniques, built on the top of IEEE 802.11, able to optimize the timing performance of the wireless network based on the application specific requirements. Several techniques are compared, all aimed at the consecutive polling of multiple stations by a central monitor node; basically the proposed techniques try to minimize the timing impact of CSMA/CA, proactively preventing collisions and soft synchronizing transmissions at upper layers.