Double-gain backscatter modulation based on chirp spread spectrum signals

This work presents an improved active backscatter tag based on a double processing gain modulation. All wireless communications remain subject to trade-offs between range, power consumption, and data rate. This research aims to increase the backscatter range without compromising power consumption. To do this, a chirp spread spectrum (CSS) modulation is used to illuminate the tag. The idea behind this work is to bounce incoming CSS signals by modulating the switching frequency of the tag with a down-chirp of identical bandwidth and duration as the incoming signal, resulting in the reflection of a constant frequency signal with significant processing gain. To encode the tag information an On-Off Keying (OOK) modulation is used. In addition, a Barker sequence is used to further improve the detectability of the tag, providing an additional processing gain on the receiver side.