Frequency Hopping Spread Spectrum (FHSS) refers to a method of hopping across multiple frequencies, and is a proven way to sidestep interference and overcome RF challenges with agility rather than brute force.

A complementary technique to address RF challenges is Direct Sequence Spread Spectrum (DSSS), which is used with all IEEE 802.15.4 2.4 GHz standard radios. This technique provides a few dB of coding gain and improvement in multi-path fading. Combining FHSS with DSSS delivers the best of both worlds-the interference rejection from FHSS and the coding gain from DSSS, properly termed "channel hopping".

As with most communications mechanisms, increasing the number of distinct channels proportionally increases the throughput of the system. In the case of TSMP, employing channel hopping on top of the 802.15.4 radio effectively increases bandwidth by 16 times. For low data rate applications, this means that even if the majority of the band is blocked by RF interference, the messages will still find a clear channel and get through. In either case, the effect of channel hopping is to greatly increase the reliability of the system.

A time slotted channel hopping (TSCH) protocol is a very efficient means to coordinate node communications. It has been demonstrated that thousands of nodes can operate in the same radio space without affecting end-to-end reliability. By contrast, dense networks of nodes using collision-based protocols like Carrier Sense Multiple Access (CSMA) can experience cascading collisions and network failure.