Abstract: Embodiments of the present disclosure relate to a terminal device (200) and a communication system (900) comprising at least one terminal device (902). The terminal device (200) comprises first circuitry (214) coupled to an antenna (202) and configured for a binary phase shift keying (BPSK) modulation based on a dual frequency signal received via the antenna. A first frequency part (204) of the dual frequency signal matches the antenna resonance frequency and is used for charging an energy storage, and a second frequency part (206) of the dual frequency signal is used for performing the BPSK modulation at a mismatched frequency of an antenna impedance. The terminal device (200) also comprises second circuitry (212) coupled to the first circuitry and configured to control a state of the first circuitry for performing the BPSK modulation. The terminal device can support BPSK backscatter with low complexity, cost, and a small size.

Abstract: A multistatic backscatter system may comprise unsynchronized devices. The unsynchronized device may comprise two or more spatially separated transmitter devices to transmit carrier signals, a transmitter device being configured to transmit carrier signals over a frequency set of two or more different frequencies; at least one backscatter device configured to frequency-shift the carrier signals, modulate data on at least some of the carrier signals, and backscatter modulated frequency-shifted carrier signals as backscatter signals, and at least one receiver device configured to receive the carrier signals and the backscatter signals, to process them to obtain the data and determine ranging information for the backscatter device.

Abstract: A multistatic backscatter system may comprise unsynchronized devices. The unsynchronized device may comprise two or more spatially separated transmitter devices to transmit carrier signals, a transmitter device being configured to transmit carrier signals over a frequency set of two or more different frequencies; at least one backscatter device configured to frequency-shift the carrier signals, modulate data on at least some of the carrier signals, and backscatter modulated frequency-shifted carrier signals as backscatter signals, and at least one receiver device configured to receive the carrier signals and the backscatter signals, to process them to obtain the data and determine ranging information for the backscatter device.

Abstract: Disclosed herein are systems, methods and/or computer programs for backscatter localization of a tag using access point (AP) mode switching. The apparatus, may comprise means for: receiving distance information associated with at least two APs from a set of at least three APs. The distance information associated with each AP of the at least two APs may be determined based on: dynamically switching the role of said each AP in a different time interval to a transmission mode for transmitting a localization signal to a tag, with the other APs in the set of APs switched to a receiving mode for receiving a backscatter signal from the tag in response to the transmitted localization signal from said each AP. Distance information determined, by the other APs, may be associated with said each AP based on the received backscatter signals corresponding to the transmitted localization signal from said each AP.