Radio channel measurements in 868 MHz off-body communications in a ferry environment

In the paper, a characterization of the 868 MHz off-body radio channel in BANs is presented. Measurements were carried out in a ferry environment using a specific set-up. A method for path loss using radio distance measurements (RDMs) was developed. It allows to automate the measurements process and make it independent from the variable speed of a moving person. Based on the observed path loss as a function of distance, the obtained values are divided into Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) conditions. The results show that, in LOS, the smallest path loss mean value (67.79 dB) and standard deviation (3.87 dB) were obtained for the placement of the mobile node (MN) on the chest (TOF) of a moving person in an approaching scenario (APR). In NLOS, the lowest path loss mean value (71.57 dB) was also obtained for the same scenario. In other scenarios, more than approximately 5 dB higher path loss mean value was obtained.