Understanding Concurrent Transmissions: The Impact of Carrier Frequency Offset and RF Interference on Physical Layer Performance

The popularity of concurrent transmissions (CT) has soared after recent studies have shown their feasibilityon the four physical layers specified by BLE 5, hence providing an alternative to the use of IEEE 802.15.4for the design of reliable and efficient low-power wireless protocols. However, to date, the extent to whichphysical layer properties affect the performance of CT has not yet been investigated in detail. This article fills this gap and provides an extensive study on the impact of the physical layer on CT-basedsolutions using IEEE 802.15.4 and BLE 5. We first highlight through simulation how the impact of errors induced by relative carrier frequency offsets on the performance of CT highly depends on the choice of theunderlying physical layer. We then confirm these observations experimentally on real hardware and withvarying environmental conditions through an analysis of the bit error distribution across received packets,unveiling possible techniques to effectively handle these errors. We further study the performance of CTbased data collection and dissemination protocols in the presence of RF interference on a large-scale testbed,deriving insights on how the employed physical layer affects their dependability.