On the suitability of the 433 MHz band for M2M low-power wireless communications: Propagation aspects

© 2013 John Wiley & Sons, Ltd. The paper evaluates outdoor and indoor propagation depending on node height at the 433 MHz and 2.4 GHz bands, as well as the effects of multipath propagation in an indoor environment in both Line-of-Sight and Non-Line-of-Sight conditions. The results show that the 433 MHz band offers better communication range in both environments but is more prone to the effects of multipath propagation.The 433 MHz band is gaining relevance as an alternative to the 2.4 GHz band for machine-to-machine communications using low-power wireless technologies. Currently, two standards are being developed that use the 433 MHz band, DASH7 Mode 2 and IEEE 802.15.4f. The article presents propagation models based on measurements conducted at the 433 MHz and 2.4 GHz bands that can be used for link budget calculations in both outdoor and indoor environments depending on node height. The results obtained show that the 433 MHz band has a larger communication range in both indoor and outdoor environments despite the negative effects of having a larger Fresnel zone. In addition, indoor propagation measurements are conducted in line-of-sight and nonline-of-sight conditions to determine the suitability of channel hopping to combat the effects of multipath propagation. Contrary to the 2.4 GHz band, the results show that channel hopping at 433 MHz does not provide any link robustness advantage because the channel coherence bandwidth is larger than the whole band bandwidth, and thus, all channels are highly correlated.