Improved Energy-Based Signal Detection for Ambient Backscatter Communications

In ambient backscatter communication (AmBC) systems, passive tags connect to a reader by reflecting an ambient radio frequency (RF) signal. However, the reader may not know the channel states and RF source parameters. The traditional energy detector (TED) appears to be an ideal solution. However, it performs poorly under these conditions. To address this, we propose two new detectors: (1) A joint correlation-energy detector (JCED) based on the first-order correlation of the received samples and (2) An improved energy detector (IED) based on the p-th norm of the received signal vector. We compare the performance of IED and TED under the generalized noise model using McLeish distribution and derive a general analytical formula for the area under the receiver operating characteristic (ROC) curves. Based on our results, both detectors outperform TED. For example, the probability of detection with a false alarm rate of 1\% for JCED and IED is 22.97\% and 5.41\% higher, respectively, compared to TED for a single-antenna reader. Using the direct interference cancellation (DIC) technique, these gains are 34.92\% and 3.7\%, respectively. With a four-antenna array at the reader and a 5\% false alarm rate, the JCED shows a significant BER improvement of 28.68\% without DIC and 48.21\% with DIC.