Toward Full Passive Internet of Things: Symbiotic Localization and Ambient Backscatter Communication

In this article, we proposed a symbiotic localization and the ambient backscatter communication (SLABC) architecture, which uses existing ambient backscatter communication (AmBC) hardware and received signals to help Internet of Things (IoT) localize target objects. The SLABC can be viewed as a specific realization of integrated passive/symbiotic sensing and communication, which has two mutually beneficial stages: 1) sensing stage with generalized Prony with homologous matching (GPHM) method and 2) communication stage with multisource constant modulus algorithm (MSCMA) method. To formulate SLABC, we propose a unified TMSC signal model to characterize the complex multisource, multipath, and multireflection symbiotic communication (TMSC), and facilitate the key information extraction. Utilizing the frequency domain expression of the unified signal model and the similarity between multipath channel coefficients and tap coefficients of equalizers, our proposed GPHM and MSCMA methods are efficient to mitigate the TMSC interference and retrieve the interested information to locate targets and communicate. The proposed SLABC concept updates the symbiotic AmBC IoT with the least cost and reduces the dependence on hardware stacking. The simulation results show that: 1) information extracted by GPHM and MSCMA can help localization achieve high accuracy and reduce the complexity of multipath interference mitigation and 2) both of the two methods have a positive influence on each other.