Coherent detector for pseudo-FSK backscatter under ambient constant envelope illuminationCoherent detector for pseudo-FSK backscatter under ambient constant envelope illumination Πλήρης Δημοσίευση σε Συνέδριο Conference Full Paper 2019-06-062018enThis work studies ambient backscatter, where the tag utilizes a frequency-shifted form of on-off keying (OOK), which may be coined as pseudo-frequency shift keying (pseudo-FSK). Such scheme, offers the possibility of simple, frequency-domain multiple access (due to FSK), by appropriate selection of the switching frequencies among (possibly receiverless) tags, while reserving bandwidth (due to OOK). A constant envelope-modulated ambient signal is assumed to illuminate the tag, resembling signals from (analog) FM radio, (digital) minimum-shift keying (MSK), or phase-shift keying (PSK) broadcasting stations. Fully coherent, maximum likelihood (ML) detection is derived for tag information, without estimating or detecting the ambient signal; instead, the law of large numbers is exploited, in conjunction with channel estimation techniques, even though the ambient unknown signal changes between successive tag bits. Closed-form expression for the probability of error is also given and simulations verify theoretical results. Ambient is a special case of bistatic backscatter; thus, useful design principles for ambient systems can stem from the bistatic backscatter literature. http://creativecommons.org/licenses/by/4.0/IEEE 19th International Workshop on Signal Processing Advances in Wireless Communications Vougioukas Georgios Βουγιουκας Γεωργιος Alevizos Panagiotis Αλεβιζος Παναγιωτης Bletsas Aggelos Μπλετσας Αγγελος Institute of Electrical and Electronics Engineers Ambient Backscatter radio Detection RFID Amplitude shift keying Backscattering Digital radio