This application discloses a tag quantity estimation system and method of RFID. A processor-readable medium was disclosed at the same time. This estimation method applies a spatial diversity gain existing in a multi-antenna system. Separated and sequentially stacked the real parts and the imaginary parts of the multiple signals received by multiple antennas. Then, a tag quantity estimation problem is converted into a data clustering problem in high-dimensional space. In this way, the overlapped cluster data in low-dimensional space can be separated in the high-dimensional space, thereby improving the accuracy of tag quantity estimation.

A method performed in a network control entity for enabling access to a wireless tag in a wireless communications network is provided. The wireless communications network includes two or more access points, APs. The network control entity configures a first AP to transmit a radio frequency signal in a first time period, and configures a second AP to receive, in the first time period, a radio signal reflected from the wireless tag using the transmitted radio frequency signal. A network control entity for enabling access to at least one wireless tag in a wireless communications network is also provided. Further, an access point AP and a method therein for enabling access to a wireless tag in a wireless communications network are also provided.

A backscatter communication method and apparatus provides operation including: receiving a first excitation signal from a first device; determining a first resource based on a candidate resource; and sending a backscattered signal of the first excitation signal to a second device based on the first resource. This can reduce a probability of selecting a same resource as another device to some extent, so that a conflict is reduced, and an access success rate of a backscatter device can be improved.

An incontinence detection system monitors an area for moisture events and wirelessly transmits moisture-related information to one or more notification devices. The system has a pad that includes a substrate and one or more sensors supported by the substrate. The sensor(s) emit wireless signals indicative of the moisture-related information. A sensor event communication system forwards the sensor signals to another device, such as a notification device. Portions of the system are included in a patient support apparatus, such as a bed.

An incontinence detection system monitors an area for moisture events and wirelessly transmits moisture-related information to one or more notification devices. The system has a pad that includes a substrate and one or more sensors supported by the substrate. The sensor(s) emit wireless signals indicative of the moisture-related information. A sensor event communication system forwards the sensor signals to another device, such as a notification device. Portions of the system are included in a patient support apparatus, such as a bed.

Devices and methods for reading multiple types of RFID tags having different frequencies and/or encoding schemes are disclosed. One or more search signals covering a plurality of RFID bands are transmitted. A presence indication of an RFID tag in one of the plurality of RFID bands is detected. An interrogating signal having a carrier frequency tuned to a frequency at which the presence indication is detected is transmitted. A tag response signal comprising tag information associated with the RFID tag is received. A digital response signal based on the tag response signal is digital signal processed to obtain the tag information.

A multi-protocol RFID interrogating system employs a synchronization technique (step-lock) for a backscatter RFID system that allows simultaneous operation of closely spaced interrogators. The multi-protocol RFID interrogating system can communicate with backscatter transponders having different output protocols and with active transponders including: Title 21 compliant RFID backscatter transponders; IT2000 RFID backscatter transponders that provide an extended mode capability beyond Title 21; EGOTM RFID backscatter transponders, SEGOTM RFID backscatter transponders; ATA, ISO, ANSI AAR compliant RFID backscatter transponders; and IAG compliant active technology transponders. The system implements a step-lock operation, whereby adjacent interrogators are synchronized to ensure that all downlinks operate within the same time frame and all uplinks operate within the same time frame, to eliminate downlink on uplink interference.

Enhanced surface acoustic wave (SAW) sensors and SAW sensor-tag wireless interface devices, including low loss devices, devices that enable enhanced use of time diversity for device identification, and devices suitable for use in band-limited environments (such as ISM band) and for use in ultra-wideband applications are disclosed. Antennas for use with both SAW sensors and/or tags, and wireless transceiver systems also are disclosed, including antennas suitable for operation in conductive media and in highly metallic environments, said antennas being used to activate and read said SAW sensors and/or tags. SAW sensors and sensor-tags and related methods for measuring scaled voltage and current in electrical conductors via measurements of the electric and magnetic fields thereof are disclosed.

An incontinence detection system monitors an area for moisture events and wirelessly transmits moisture-related information to one or more notification devices. The system has a pad that includes a substrate and one or more sensors supported by the substrate. The sensor(s) emit wireless signals indicative of the moisture-related information. A sensor event communication system forwards the sensor signals to another device, such as a notification device. Portions of the system are included in a patient support apparatus, such as a bed.

A radio frequency identification (RFID) system includes an RFID interrogator configured for generating an RFID signal, wherein a channel frequency of the RFID signal changes over time; at least one patch antenna; and at least one feed line configured for feeding the signal to the corresponding at least one patch antenna. In another exemplary embodiment, an RFID interrogator configured for generating an RID signal, wherein a channel frequency of the RFID signal changes over time; at least one transmission line; and a diplexer coupling the RFID interrogator and the transmission lines and configured for distributing the RFID signal to each of the antennas or transmission lines, respectively, depending on the channel frequency of the RFID signal generated. The antennas or transmission lines are configured to transmit an electromagnetic wave in response to and at the channel frequency of the RFID signal distributed thereto.