Experimental Analysis of Multi-AP Diversity for Reliable Industrial Communications

This paper presents the results of a measurement campaign carried out in an industrial-like environment to evaluate the benefits of a multi-Access Point (AP) architecture in enhancing the performance of wireless communications in such environments. The signal levels received by a moving receiver along four trajectories from four transmitters are recorded. The microdiversity is studied by computing the autocorrelation function and the macrodiversity by the cross correlation function of the signal level variation along the trajectories. The tests were performed at the 6 GHz band, a strong candidate for industrial wireless communication in the near future. The results show that microdiversity does not bring relevant benefits for distances below 10 cm, while high macrodiversity is obtained using several AP. These results lead to the conclusion that for small-size devices the use of multiple AP (macrodiversity) significantly outperforms microdiversity (multiple antennas at the receiver side).