Abstract: A mobile device for data communications has a radio circuit for data communications with a wireless network access point and a radio tag for transmitting location-identifying radio signals. The radio circuit and the radio tag are co-located on a circuit board or are commonly powered. The operation of the radio circuit and the radio tag are segregated in time to avoid interference. Standard wireless network interface protocol functions are exploited to identify time intervals in which the radio circuit is inactive for data communications. These time intervals are used to operate the radio tag to transmit the location-identifying radio signals.

Abstract: Association request messages received by one or more access points of a wireless local area network are used to infer the location of a mobile unit requesting association. Association may be refused for security purposed if it is determined that the mobile unit is not within an area services by the wireless network. In addition the inferred location can be used to assign the mobile unit to an access point for association.

Abstract: The location of unmodified wireless assets in a wireless communication network may be identified using time differences of arrivals of a communication sequence at different network receivers. Time-stamping devices may include correlator circuits in parallel with signal decoders to time-stamp communication sequences. Cellular wireless networks may be frequency-multiplexed to increase spatial time-stamping density. Tags may be attached to passive assets to provide location identification information to network devices. Locations of assets broadcasting standard 802.11 radio frequency structures may be identified. Noise inherent in correlating a communication sequence may be reduced by using a selected correlation function.

Abstract: A system and method for locating assets within an area, each asset having a wireless circuit configured for low power consumption, the method comprising. The method including the steps of providing power to an RFID tag portion of the wireless circuit, and supplying power to a high power portion of the wireless circuit after a triggering event, for example: the purchase of the asset. The high power portion of the wireless circuit is prevented from accessing power from the battery prior to the triggering event.

Abstract: The present invention describes a system for interrogating or updating electronic shelf tags in a store or warehouse without the need for a complicated or expensive infrastructure. In the system, a single portable RFID device is carried by a worker to perform tasks such as organizing goods on the shelves of a store or a warehouse. As the worker traverses the aisles he may use the portable RFID device to scan each RFID tag as it comes within range. Through a wireless connection to a central controller on which pricing information is stored, the portable RFID device is able to verify that the information located in each RFID tag is correct. If the information is not correct, it can be updated with the correct information from the central controller. Alternatively, the RFID device may be self-contained and have all the correct pricing information stored on an internal memory.

Abstract: A wireless data communications system has mobile units which become associated with access points. Association between a mobile unit and an access point is changed as mobile units move within an area having a plurality of access points. Selection of an access point for association with a mobile unit is made according to selection criteria including a plurality of selection parameters. The system includes arrangements for determining location of a mobile unit within the area. The selection parameters include location of the mobile unit or direction of movement of the mobile unit when there are a plurality of access points available for association with the mobile unit.

Abstract: The location of unmodified wireless assets in a wireless communication network may be identified using time differences of arrivals of a communication sequence at different network receivers. Time-stamping devices may include correlator circuits in parallel with signal decoders to time-stamp communication sequences. Cellular wireless networks may be frequency-multiplexed to increase spatial time-stamping density. Tags may be attached to passive assets to provide location identification information to network devices. Locations of assets broadcasting standard 802.11 radio frequency structures may be identified. Noise inherent in correlating a communication sequence may be reduced by using a selected correlation function.

Abstract: A system for locating mobile units in a data communications system based on signal strength measurements of mobile unit transmissions is calibrated for variations in mobile unit transmitter power by determining range of a mobile unit from an access point using two way time ranging. The time ranging is compared to the value for range based on signal strength and a correction value for the mobile unit is updated based on the difference between range based on time ranging and the range based on signal strength.

Abstract: The location of unmodified wireless assets in a wireless communication network may be identified using time differences of arrivals of a communication sequence at different network receivers. Time-stamping devices may include correlator circuits in parallel with signal decoders to time-stamp communication sequences. Cellular wireless networks may be frequency-multiplexed to increase spatial time-stamping density. Tags may be attached to passive assets to provide location identification information to network devices. Locations of assets broadcasting standard 802.11 radio frequency structures may be identified. Noise inherent in correlating a communication sequence may be reduced by using a selected correlation function.

Abstract: The location of unmodified wireless assets in a wireless communication network may be identified using time differences of arrivals of a communication sequence at different network receivers. Time-stamping devices may include correlator circuits in parallel with signal decoders to time-stamp communication sequences. Cellular wireless networks may be frequency-multiplexed to increase spatial time-stamping density. Tags may be attached to passive assets to provide location identification information to network devices. Locations of assets broadcasting standard 802.11 radio frequency structures may be identified. Noise inherent in correlating a communication sequence may be reduced by using a selected correlation function.

Abstract: A method for providing information concerning an item includes attaching to the item an information button containing data identifying the item. An identifying location system transmitter is also provided on the item. The information button is read and the data identifying the item is stored on a computer, associated with data identifying the location system transmitter. A location system is used to locate the item by transmissions from the identifying location system transmitter. The data identifying the item is retrieved from the computer using the location system transmitter identifying data.

Abstract: A mobile device for data communications has a radio circuit for data communications with a wireless network access point and a radio tag for transmitting location-identifying radio signals. The radio circuit and the radio tag are co-located on a circuit board or are commonly powered. The operation of the radio circuit and the radio tag are segregated in time to avoid interference. Standard wireless network interface protocol functions are exploited to identify time intervals in which the radio circuit is inactive for data communications.

Abstract: A wireless data communications system has mobile units which become associated with access points. Association between a mobile unit and an access point is changed as mobile units move within an area having a plurality of access points. Selection of an access point for association with a mobile unit is made according to selection criteria including a plurality of selection parameters. The system includes arrangements for determining location of a mobile unit within the area. The selection parameters include location of the mobile unit or direction of movement of the mobile unit when there are a plurality of access points available for association with the mobile unit.

Abstract: A radio signal based object location system is provided wherein location devices are provided on articles for use in locating the articles, and wherein a database is maintained relating characteristics of radio signal transmissions between the location devices and fixed devices to locations within an area. A method is provided for maintaining the database to reflect propagation conditions. Location devices are provided at fixed positions within the area. Data representing radio signal transmission characteristics between the fixed position location devices and fixed devices is recorded. Transmissions between the fixed position location devices and the fixed devices is monitored to determine changes in the characteristics of radio signal transmissions from the recorded data.

Abstract: A radio signal based object location system is provided wherein location devices are provided on articles for use in locating the articles, and wherein a database is maintained relating characteristics of radio signal transmissions between the location devices and fixed devices to locations within an area. A method is provided for maintaining the database to reflect propagation conditions. Location devices are provided at fixed positions within the area. Data representing radio signal transmission characteristics between the fixed position location devices and fixed devices is recorded. Transmissions between the fixed position location devices and the fixed devices is monitored to determine changes in the characteristics of radio signal transmissions from the recorded data.

Abstract: The division of the 802.11 MAC operation into a lower MAC and an upper MAC is described. The lower MAC functionality is provided by a combination of software commands and an RF driver. The RF driver is intended to be appliance independent and will not change based on what type of 802.11 node is being implemented: Mobile Unit (MU), Access Point (AP), Wireless AP (WLAP), phone, pager, etc. The RF driver is not hardware platform independent, due to variations in DMA capability and allotted timers. The upper MAC is intended to be hardware platform independent, but appliance dependent (i.e. it will change based on the product being implemented such as PCMCIA, USB, PCI, etc.).

Abstract: Portable devices are provided with location data determined at a server computer by comparing radio signal characteristics to a database of characteristics. In one arrangement the server additionally downloads a portion of the database of radio signal characteristics to the portable device and the portable device uses the downloaded portion of the data base to determine if its location has changed. The portable device may either update the location data that it has previously downloaded from the server or alternately may signal the server to provide either updated location data or an increased rate of location data update.

Abstract: The division of the 802.11 MAC operation into a lower MAC and an upper MAC is described. The lower MAC functionality is provided by a combination of software commands and an RF driver. The RF driver is intended to be appliance independent and will not change based on what type of 802.11 node is being implemented: Mobile Unit (MU), Access Point (AP), Wireless AP (WLAP), phone, pager, etc. The RF driver is not hardware platform independent, due to variations in DMA capability and allotted timers. The upper MAC is intended to be hardware platform independent, but appliance dependent (i.e. it will change based on the product being implemented such as PCMCIA, USB, PCI, etc.).

Abstract: A system for locating mobile units in a data communications system based on signal strength measurements of mobile unit transmissions is calibrated for variations in mobile unit transmitter power by determining range of a mobile unit from an access point using two way time ranging. The time ranging is compared to the value for range based on signal strength and a correction value for the mobile unit is updated based on the difference between range based on time ranging and the range based on signal strength.

Abstract: Association request messages received by one or more access points of a wireless local area network are used to infer the location of a mobile unit requesting association. Association may be refused for security purposed if it is determined that the mobile unit is not within an area services by the wireless network. In addition the inferred location can be used to assign the mobile unit to an access point for association.