Symbol Technologies, LLC

Extreme Networks, Inc.

Chris Zegelin

David P Goren

Raj Bridgelall

Dean Mamoru Kawaguchi

Benjamin J Bekritsky

Sarosh N Vesuna

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.

Interference mitigation in mobile units having location transmitters

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.

Method for mobile unit location estimate in a wireless LAN

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.

Methods and apparatus for identifying asset location in communication networks

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.

WLAN roaming based on location

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.

Self calibration of signal strength location system

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.

Location system with calibration monitoring

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.).

Wireless device which uses an upper MAC and lower MAC interface

An interface chip for a peripheral module connectable to and for use with a host computer is provided which utilizes an static Random access memory (SRAM) within the interface chip for both encryption of data packets and temporary storage of Card Information Structure (CIS) information. The CIS information is stored in the SRAM only during the power-up phase of operation, when encryption of data packets is not necessary and thus the memory is not being utilized for that purpose. This precludes the need for a separate SRAM IC, thus saving space on the card.

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San Jose, CA, United States of America

Chris Zegelin