A transceiver may wirelessly transmit a communication signal at a first frequency and a sensing signal at a second frequency. The communication signal may include a command that causes a backscatter node to modulate impedance of an antenna, and thereby modulate reflectivity of the backscatter node. The communication signal may also deliver wireless power to the backscatter node. While the impedance is being modulated in response to the command, the transceiver may transmit the sensing signal and measure wireless reflections. The power of the sensing signal may be much lower than that of the communication signal. The transceiver may frequency hop the sensing signal in a wide band of frequencies and take measurements at each frequency in the hopping. Based on the measurements, a computer may determine time-of-flight or phase of a reflected signal from the backscatter node and may estimate location of the backscatter node with sub-centimeter precision.

An occupant detection system for determining a unique position of a detected presence within an interior cabin area of a vehicle includes a plurality of signal conversion devices each including conversion circuitry. Each of the plurality of signal conversion devices are assigned to a specific position within the interior cabin area of the vehicle. The conversion circuitry for the plurality of signal conversion devices include unique sub-carrier frequency that corresponds to the unique position within the interior cabin area of the vehicle. The occupant detection system includes a wireless control module including a multi-band transceiver having a first transceiver configured to transmit and receive signals on a first frequency band and a second transceiver configured to transmit and receive signals on a second frequency band.

A system for remote monitoring a network of distributed antennas. The system including at least one antenna electrically coupled to a radio-frequency (RF) transmission line, and a monitoring module electrically coupled to the RF transmission line, the monitoring module configured to receive a direct-current (DC) coded signal via the RF transmission line and compare the DC coded signal to at least one code saved in a memory of the monitoring module to determine a status associated with the at least one antenna.

A transmission apparatus for a wireless device, comprising: an antenna for receiving an original signal and for backscattering a modulated signal containing information from the wireless device; a variable impedance coupled to the antenna, the variable impedance having an impedance value; a delta-sigma modulator coupled to the variable impedance for modulating the impedance value, and thereby a backscattering coefficient for the antenna, in accordance with the information to generate the modulated signal; and, a decoder coupled to the delta-sigma modulator for generating the impedance value from the information.

A backscatter tag communicate device includes, in part, a receiver configured to receive a WiFi packet conforming to a communication protocol defining a multitude of codewords, a mapper configured to map at least a first subset of the multitude of codewords disposed in the packet to a second multitude of codewords defined by the protocol, and a frequency shifter configured to shift a frequency of the second multitude of codewords such that the frequency shifted codewords are characterized by a single sideband spectrum. The communication protocol may be the 802.11b communication protocol. The mapper may optionally map the first subset of the multitude of codewords by changing phases of the first subset of the multitude of codewords.

A system and method for determining the relative position of stations through radio location is proposed. In one aspect, a station is configured as an apparatus having at least one antenna. At least one first station has at least one first antenna, and at least one second station has at least two base-modulated antennas. The first station sends at least one locating signal via the first antenna. The second station reflects the locating signal as a first modulated reflected locating signal via a first base-modulated antenna and as a second modulated reflected locating signal via a second base-modulated antenna. The first station receives the modulated reflected locating signals via the antenna. The phase relationships of the received modulated reflected locating signals are used to ascertain at least one position angle for the relative position between the first station and the second station.

An RFID tag is attached to or embedded in an object and used for determining the position of the object. The RFID tag includes a controller and an energy harvester coupled to the controller. The controller provides object position information to a host device by sending ping signals to the host device. The energy harvester harvests RF energy from WLANs, converts the RF energy to DC power, and supplies the DC power to the RFID tag.

Object localization with an radio-frequency identification (RFID) infrastructure is described. A plurality of transmission power levels established by an RFID reader can be searched to determine a measurement power level corresponding to a target. A region that includes the target can then be determined using information about a physical relationship between the RFID reader and a reference location via correlating the measurement power level to a reference power level corresponding to the reference location.

A method for determining a location of a battery-less wireless tag by a tag reader being at a fixed-location. The method comprises: transmitting, by the tag reader, at least one wireless signal having a controlled known energy; receiving at the tag reader at least one packet transmitted by the tag within a time window; and responsive to a determination at the tag reader of at least one transmission rate of packets by the wireless tag based on the at least one received packet, determining information regarding the location of the tag.

System and method of quickly determining the locations of radio-frequency identification (RFID) tags. Instead of determining the locations based on receiving a full response to the read command, the system uses the initial tag response, which enables it to operate more quickly as part of an initial scan. The system then follows up on the initial scan with read commands to read the RFID tag identifier using only the antennas with RFID tags present, as determined by the initial scan. As a result, the time to determine the locations of the RFID tags is reduced.