  In this paper we present a new modulation, called DLoRa, similar in principle
to the conventional LoRa modulation and compatible with it in terms of
bandwidth and numerology. DLoRa departs from the conventional LoRa modulation
as it is using a decreasing instantaneous frequency in the chirps instead of an
increasing one as for the conventional LoRa modulation. Furthermore we describe
a software environment to accurately evaluate the "isolation" of the different
virtual channels created both by LoRa and DLoRa when using different Spreading
Factors. Our results are in agreement with the ones present in literature for
the conventional LoRa modulation and show that it is possible to double the
number of channels by using simultaneously LoRa and DLora. The higher (double)
number of subchannels available is the key to improve the network level
performance of LoRa based networks.
