Hard real time guarantee over IEEE 802.11 wireless LANS

In industrial applications, the need of using wireless technology is increasing. Tow major advantages are the reduced cabling needed and the possibility to have truly mobile stations such as mobile robots. Thus, IEEE 802.11 PCF mode is defined to support time bounded applications in wireless LAN. From the fact that EDF (Earliest Deadline First) scheduling policy is optimal in central context, we propose in this paper to combine PCF mode with EDF policy. This leads to predict the response time of hard real time messages and to give guarantee of respecting message transmission deadlines. A detailed description of how to exactly bound messages worst case response time is also gives.