IEEE 802.15.4 Channel Diversity in an Outdoor Environment

Abstract

Low-power wireless link quality is known to be frequencydependent because of multipath fading and other factors. We present a performance study of IEEE 802.15.4 radio links that quantifies and analyzes this frequency-specific performance in a clear-field outdoor environment. Using data from 16 channels on 240 links, we show that effect from channel selection on the average link is up to 4.89 dB, comparable with the effect from 38.7• C change in temperature. These results provide a performance baseline for other environments, as the diversity can be expected to further increase in environments with more obstacles and external interference.

Scheduling High-Rate Unpredictable Traffic in IEEE 802.15.4 TSCH Networks

“…Under normal channel conditions the overallocated slots remain idle. Wireless link studies [2] [3] [4] show that even though wireless link quality is occasionally correlated (e.g., because of regional external interference), some spatial diversity is always present as well. Given this spatial diversity assumption, we can conclude that it is very unlikely that all links are going to suffer from bad performance at the same time.…”

“…We show that the throughput is increased if either: (a) there are significant differences in the quality of links between multiple upstream nodes and the same upstream node. Numerous real-world studies [2] [3] [4] confirm that this is fair assumption in low-power wireless networks; links spatially separated by less than a meter often show completely different performance. Or, (b) the nodes have unequal requirements in terms of how many messages they need to transmit.…”