The grey area in wireless communications: A multiplatform experimental study

Experimental studies in wireless sensor networks reveal a region with random packet loss and highly unreliable links. Some studies refer to the region as the Grey Area. This area may affect upper layer protocol performance. Unlike previous studies, our paper presents an experimental study of link performance using three different hardware platforms: one for Radio Frequency Identification (RFID) and two for Wireless Sensor Networks (WSNs). Therefore, our study considers short and long distance (up to 400 meters) behavior. The study measures Received Signal Strength Indicator (RSSI) values and Packet Reception Ratio (PRR). Preliminary results demonstrate that the Grey Area appears in all platforms and it occupies a maximum 28.6% of the radio range. However, one WSN platform (XbeePro900) presents the smaller proportional Grey Area. Moreover, our results support the hypothesis that Grey Area is mainly due to SNR decrease because of attenuation, and previously proposed explanations such as multipath and shadowing may be negligible. Additionally, we verified that better radio technologies experience a smaller grey area.