Abstract: The present invention is related to a low-power backscatter system comprising a LiFi, “Light Fidelity”, transmitter configured for generating and transmitting an optical signal comprising a sequence of a downlink data signal and a chirp signal and an IoT, “Internet of Things”, tag.

Abstract: Wireless local area networks (WLANs) provide wireless communication between various wireless devices. Frames are acknowledged (ACKed) after a short and predefined MAC idle time. The MAC idle time varies with 1) the physical distance between wireless devices, caused by the delay of wireless signal propagation, and 2) the time to detect the ACK at the local wireless device, which varies with the signal strength of the incoming ACK. Embodiments present CAESAR (CArriEr Sense-bAsed Ranging), which combines time of flight (TOF) and signal-to-noise ratio (SNR) measurements to calculate the distance between two wireless devices. CAESAR measures the distance by estimating the MAC idle time in a data/ACK communication at a particular clock resolution and the ACK detection time on a per-frame basis. Performance measurements confirm the accuracy of the solution and show the capability to track the distance to WLAN smart phones at pedestrian speeds.

Abstract: LEDs that transmit or receive data in a VLC may create a flickering effect which is observed when the human eye is able to perceive the fluctuations of the light intensity in a LED. To prevent flickering, the LEDs may emit light based on a pattern of data and energy intervals. During the data intervals, a LED transmitting a message sends one or more data symbols to receiving LEDs. The receiving LEDs, however, are reversed bias and do not emit light. During the energy intervals, any LED in the VLC system may emit light. Each LED uses the energy interval to compensate for the light transmitted (or not transmitted) during the data interval. The combination of data and energy levels results in an observer seeing light with a constant intensity rather than changing intensity.

Abstract: LEDs that transmit or receive data in a VLC may create a flickering effect which is observed when the human eye is able to perceive the fluctuations of the light intensity in a LED. To prevent flickering, the LEDs may emit light based on a pattern of data and energy intervals. During the data intervals, a LED transmitting a message sends one or more data symbols to receiving LEDs. The receiving LEDs, however, are reversed bias and do not emit light. During the energy intervals, any LED in the VLC system may emit light. Each LED uses the energy interval to compensate for the light transmitted (or not transmitted) during the data interval. The combination of data and energy levels results in an observer seeing light with a constant intensity rather than changing intensity.

Abstract: Wireless local area networks (WLANs) provide wireless communication between various wireless devices. Frames are acknowledged (ACKed) after a short and predefined MAC idle time. The MAC idle time varies with 1) the physical distance between wireless devices, caused by the delay of wireless signal propagation, and 2) the time to detect the ACK at the local wireless device, which varies with the signal strength of the incoming ACK. Embodiments present CAESAR (CArriEr Sense-bAsed Ranging), which combines time of flight (TOF) and signal-to-noise ratio (SNR) measurements to calculate the distance between two wireless devices. CAESAR measures the distance by estimating the MAC idle time in a data/ACK communication at a particular clock resolution and the ACK detection time on a per-frame basis. Performance measurements confirm the accuracy of the solution and show the capability to track the distance to WLAN smart phones at pedestrian speeds.

Abstract: A driver for an IEEE 802.11 wireless network node determines a metric for link quality between the node and a remote node. The nodes communicate using a handshake protocol in which the first node expects to receive an acknowledgement (ACK) of receipt of a data packet from the remote node. The driver provides a measure for: collision induced losses (pc) between the first and remote nodes; a slot being erroneously detected as busy when a successful transmission could have been made (pexp) between the first and remote nodes; and a probability of successful reception of a packet when a collision occurs (pplc) between the first and remote nodes. The measure is based on a number (A) of acknowledgements received from the remote node vis-à-vis a number (T) of packets transmitted to the remote node. The driver can adjust one of carrier sensitivity or node transmission power based on the measure.

Abstract: A driver for an IEEE 802.11 wireless network node determines a metric for link quality between the node and a remote node. The nodes communicate using a handshake protocol in which the first node expects to receive an acknowledgement (ACK) of receipt of a data packet from the remote node. The driver provides a measure for: collision induced losses (pc) between the first and remote nodes; a slot being erroneously detected as busy when a successful transmission could have been made (pexp) between the first and remote nodes; and a probability of successful reception of a packet when a collision occurs (pplc) between the first and remote nodes. The measure is based on a number (A) of acknowledgements received from the remote node vis-à-vis a number (T) of packets transmitted to the remote node. The driver can adjust one of carrier sensitivity or node transmission power based on the measure.