Impinj, Inc.

Airespace, Inc.

Cisco Technology, Inc.

Cisco Systems Inc.

Paul F Dietrich

Robert J Friday

Christopher J Diorio

Robert B O'Hara, Jr

Patrice R Calhoun

Gregg Scott Davi

Kurt Eugene Sundstrom

Alexander H Hills

Todd E Humes

Ali Aiouaz

David Anthony Frascone

Harley K Heinrich

Sudhir Kumar Jain

Brett D Galloway

Omar Khwaja

Brent A Picasso

Andrew Friefeld

Michael J Dacquisto

Joseph Baird

Gregory T Kavounas

Scott A Cooper

Theron Stanford

Aanand Esterberg

Chad A Lindhorst

Kambiz Rahimi

Robert B O'Hara

David Ord

Mathew Douglas Howard

Matthew Douglas Howard

Patrice R Calhous

According to one embodiment, a method includes monitoring, at one or more wireless network access elements, signal strength of signals transmitted by respective neighboring wireless network access elements. Information is collected from said wireless network access elements and converted into reportable data about signal strength observed during the monitoring. The method further includes identifying, based at least in part on interference associated with concurrent signal transmissions of the wireless network access elements, a combination of channel assignments for the one or more wireless network access elements from a plurality of possible combinations of channel assignments and assigning channels for concurrent, respective use by said wireless network access elements based on the identified combination of channel assignments.

Method and system for dynamically assigning channels across multiple radios in a wireless LAN

A preemptive roaming mechanism in wireless network environments. In one implementation, the present invention provides a wireless client that implements a preemptive roaming mode that, when an attribute of the signal (e.g., Signal to Noise Ratio (SNR), etc.) between the access point with which the client is currently associated crosses a threshold, scans for other access points with which to associate. In one implementation, the client switches between the scanning mode and a traffic mode to allow data to be transferred between the client and the current access point. The pre-emptive roaming functionality can be configured to support desired data rates or other QoS levels.

Pre-emptive roaming mechanism allowing for enhanced QoS in wireless network environments

In a fixed channel wireless network system with a limited number of channels, assignment of the fixed channels between remote client elements and access elements is made systematically according to a set of criteria accounting for network loading and interference, then channel assignments are dynamically updated according to a priority to maintain optimal network performance with changing conditions of load and interference. The channel utilization problem is address at a system level rather than at a local level by treating the system as a three dimensional color mapping problem. All noise is treated as having a source in virtual access elements with an appropriate performance metric. The performance metric is used to select a channel set that minimize chances of interference and maximize user performance. Specifically, there are several parameter matrices which are managed and updated by a central resource management element, namely signal strength between elements, interference, and load. These matrices are used to find the optimal channel assignments for a predetermined limited set of assignable channels. In one implementation, the channel assignment methodology takes into account the interference associated with access elements operating on a selected channel, as well as the interference or energy that spills over (or is otherwise observable) on physical channels adjacent to the selected channel.

An RFID reader uses an adaptive filter to mitigate the effects of colored noise in tag reply signals. The adaptive filter may be a linear equalizer, a linear-predictive canceller, or a decision-feedback equalizer. The adaptive filter estimates the colored noise portion of the signal received from the tag and removes the noise estimate from the tag signal. The adaptive filter bases its noise estimate on the difference between a desired signal and a portion of the received signal. The reader uses reader-generated training data, a CW signal, and/or portions of the tag reply signal to adapt the filter.

RFID readers mitigating colored noise

RFID tags and chips for RFID tags are capable of being inventoried in one or more early attempts. These tags are capable of then refraining from participating in one or more subsequent inventorying attempts. In some embodiments refraining is performed solely by the tag, while in others it is guided by the RFID reader. In some embodiments, an inventoried indicator in the tag becomes updated upon backscattering. The updated value is used by the tag to recognize a subsequent attempt, and thus refrain from participating in it. This permits the subsequent attempt to be used more intensively for inventorying the more elusive, harder-to-read tags, especially in more demanding scenarios.

RFID tag chips and tags refraining from participating in a subsequent inventorying attempt and methods

Rogue RFID readers are detected by listening to communication between rogue reader and a tag, capturing an identifier associated with the tag from the communication by the reader or by the tag, and checking the captured identifier to determine whether it is a result of a command from another legitimate reader. Audible or visible alerts may be issued, flags may be set, or messages transmitted to an administrator upon determining the operation of the rogue RFID reader. Based on the alert(s) affected tags or the rogue reader may be jammed or an effect of the illegal transmission by the rogue reader may be reversed or tags replaced.

Dealing with rogue RFID readers using tag identifiers

A wireless node location mechanism that defines a search region to optimize the computations associated with estimating the location of a given wireless node. According to one implementation, a coverage map associated with each radio receiver that records signal strength data is defined out to a threshold signal strength level. Before computing the estimated location of a given wireless nodes, a search region is defined based on the intersection of the coverage maps associated with each radio receiver that detects the wireless node. Some implementations use information provided by the fact that certain radio receivers did not detect the wireless node to further optimize the location estimate. By defining a search region, which is a generally small area relative to the space encompassed by an entire RF environment, the present invention provides several advantages, such as reducing the processing time and/or power to compute estimated locations for wireless nodes.

Wireless node location mechanism featuring definition of search region to optimize location computation

A wireless node location mechanism that employs a differential signal strength metric to reduce the errors caused by variations in wireless node transmit power, errors in signal strength detection, and/or direction-dependent path loss. As opposed to using the absolute signal strength or power of an RF signal transmitted by a wireless node, implementations of the location mechanism compare the differences between signal strength values detected at various pairs of radio receivers to corresponding differences characterized in a model of the RF environment. One implementation searches for the locations in the model between each pair of radio receivers where their signal strength is different by an observed amount.

Enhanced wireless node location using differential signal strength metric

Radio frequency identification (RFID) tags selected for inventorying using combination of preselect and/or post select criteria. The selection commands can be for selecting according to a tag memory content, by invoking the mask address or by comparing other tag characteristics. Selection criteria can be determined locally at a modem block of a reader or provided to the modem block by higher layers of the reader. Tags meeting the selection criteria are reported to the higher layers for further actions. Some tags may be held while waiting for instructions from the higher layer block(s).

Local processing of received RFID tag responses

RFID readers, reader systems, and methods are provided that utilize smart antenna switching. A first signal is transmitted from a first antenna estimating presence of tags within the antennas field of view. If fewer than a predefined number of tags are estimated, the system switches to a second antenna. Otherwise, the tags found in the field of view of the first antenna are inventoried before switching to the second antenna.

RFID readers and systems with antenna switching upon detecting too few tags and methods

Methods, apparatuses and systems facilitating location or containment of rogue or unauthorized access points on wireless computer network environments. Embodiments of the present invention support one to a plurality of rogue containment methodologies. A first rogue containment type involves identification of the physical connection of the rogue access point to the wired network infrastructure and, thus, allows for disabling of that physical connection to contain the rogue access point. Other rogue containment methods involve wireless techniques for containing the effect of rogue access points. In some embodiments, the present invention provides methods, apparatuses and systems facilitating network location of rogue access points to determine whether one or more rogue containment methodologies should be applied. As discussed below, the rogue location and containment functionality described herein can be applied to a wide variety of wireless network system architectures.

Discovery of rogue access point location in wireless network environments

Methods, apparatuses and systems facilitating containment of the effects of rogue or unauthorized access points on wireless computer network environments. Embodiments of the present invention support one to a plurality of rogue containment methodologies. A first rogue containment type involves identification of the physical connection of the rogue access point to the wired network infrastructure and, thus, allows for disabling of that physical connection to contain the rogue access point. Other rogue containment methods involve wireless techniques for containing the effect of rogue access points. As discussed below, the rogue containment functionality described herein can be applied to a wide variety of wireless network system architectures.

Containment of rogue systems in wireless network environments

Rogue RFID readers are detected by listening to communication between rogue reader and a tag, capturing a time stamp and/or a channel associated with the communication, and checking the captured time stamp/channel to determine whether it is a result of a command from another legitimate reader. Audible or visible alerts may be issued, flags may be set, or messages transmitted to an administrator upon determining the operation of the rogue RFID reader. Based on the alert(s) affected tags or the rogue reader may be jammed or an effect of the illegal transmission by the rogue reader may be reversed or tags replaced.

Growing community of inventors

Seattle, WA, United States of America

Paul F Dietrich