Unlicensed systems operating on a static frequency channel are often plagued by interference and co-existence problems. SenzaNET is optimized for transmission of relatively small amounts of data, and therefore occupies only a tiny fraction of the available spectrum at any given point in time. Its intelligent, selective use of the spectrum and frequency agility provide maximum robustness and protection against interferers:

 

• All nodes are tightly time synchronized and transmit in their assigned timeslots only. This Time Division Multiple Access (TDMA) scheme eliminates collisions and provides deterministic latency.

• The IEEE 802.15.4 radio employs a Direct Sequence Spread Spectrum (DSSS) transmission scheme, which spreads the signal over a range of frequencies to assure robustness against signals from narrowband interferers.

• Channel hopping is a proven and effective strategy to withstand interference from the myriads of devices that increasingly crowd the 2.4 GHz band and to mitigate sensitivity to fading in heavy multipath environments. The SenzaNET framework employs a rapid hopping algorithm capable of sustaining the performance and integrity of the wireless network even under extreme conditions.  

 

 

SenzaNET combines TDMA, DSSS and channel hopping methods with a robust link layer and true mesh networking. Successful reception of transmissions is acknowledged on a per-packet basis, and the protocol will automatically retry delivery if the receiving station doesn‘t acknowledge within the expected period of time. Furthermore, redundant mesh or hybrid topologies effectively protect against failure of individual network components. Field tests have consistently demonstrated that a transmission reliability of greater than 99.9% can be achieved, even in harsh industrial environments.