Cisco Technology, Inc.

Cisco Systems Wireless Networking (Australia) Pty Limited

G2 Microsystems Pty. Ltd.

John D O'Sullivan

Brian Donald Hart

Philip J Ryan

Richard A Keaney

Andrew Robert Adams

Neil Weste

Kevin C H Wong

David James Skellern

Kurt A Lumbatis

Milind Paranjpe

Jason R Crawford

Geoffrey J Smith

John S Gloekler

Uri Parker

Thangadurai Arivoli

Grzegorz B Zyner

Thomas Dejanovic

An apparatus for and a method of wirelessly receiving a signal, and detecting a start of packet (SOP) from the received signal using at least one SOP detection criterion. In the case an SOP is detected, determining a plurality of metrics from the received signal, and using at least two of the plurality of metrics to determine an initial timing for a received packet. Different versions combine the metrics in different ways to determine the initial timing. The apparatus includes a processing circuit coupled to a radio receiver to determine a plurality of metrics from a wirelessly received signal, and an initial time determining circuit coupled to the SOP detector and the processing circuit. In the case an SOP is detected, the initial time determining circuit uses at least two of the plurality of metrics to determine an initial timing for a received packet.

Initial timing estimation in a wireless network receiver

An apparatus, a carrier medium storing instructions to implement a method, and a method in a node of a wireless network able to receive packets that exactly or substantially conform to a wireless network standard according to which each packet includes a header having bits that have respective correct values in the case that the packet exactly conforms to the standard. The method includes receiving a start-of-packet (SOP) trigger that indicates that a packet may have been received, checking one or more bits in the header to determine whether or not they have their respective correct values, and continuing to process the packet in the case that the checking indicates that the checked bits have their respective correct values. In one implementation, the header includes a first field modulated at a known rate that has one or more reserved bit locations, and a second field modulated at a data rate indicated in the first field. In such an implementation, the checking includes processing the first field and checking one or more bits in the first field to determine whether or not they have their respective correct values, and, if the checked bits of the first field have their respective correct values, checking the second field for integrity.

Early detection of false start-of-packet triggers in a wireless network node

A method and an apparatus for radiolocation using time differences of arrival. The method includes receiving transmit timestamps from a set of wireless stations of a wireless network. Each station transmits at least once. The transmit timestamp uses a local timestamping clock to indicate when a station transmitted a packet. The method further includes receiving sets of timestamped captured samples from each station that receives one of the transmitted packets. The times of arrival of each packet at each station are determined from the received sets of timestamped captured samples, and, the relative positions of the stations are determined from the determined times of arrival and the received transmit timestamps. The transmitting by the stations is in a round robin manner one station after the other, and several round robins may be used to mutually calibrate local clocks. Also an apparatus for inclusion in a station of a wireless network. The apparatus includes a buffer subsystem and a timestamping subsystem, such that the station can capture and timestamp a set of samples of a received signal, and send the captured timestamped samples to a processing entity for time difference of arrival location determination.

Radiolocation in a wireless network using time difference of arrival

A method and apparatus for estimating channel characteristics in a multicarrier wireless receiver such as an OFDM wireless receiver. The method includes determining a channel estimate for each of a set of subcarriers by receiving multicarrier data as a result of a wireless transmission of data that includes a known signal, wherein the determining uses a part of the received data that corresponds to the known signal. The method further includes smoothing the channel estimates according to a smoothing filter to form smoothed channel estimates. The smoothed channel estimate for a particular subcarrier includes a contribution from the channel estimates of one or more subcarriers nearby the particular subcarrier take advantage of correlation that may exist between the particular subcarrier's channel and the channels of the one or more nearby subcarriers. In one version, the transmitted data includes at least one additional known signal, and each smoothed channel estimate is a smoothed version of the average of sets of channel estimates. In such a version, each set of channel estimates is determined using a respective part of the received data that corresponds to a corresponding one of the known signals.

Channel estimation in a multicarrier radio receiver

A wireless local area network system comprises a 5.0+ GHz radio transceiver with two receiving antennas and one transmitting antenna. A transmitter power amplifier output is connected to the transmitting antenna through a 6-8 pole filter to control spurious signal output. Each receiving antenna is fitted with its own low-noise amplifier followed by a simple bandpass filter. Each bandpass filter feeds a diversity switch with a single output to a single receiver. The radio system constitutes a physical-layer (PHY) part of a wireless local-area network.

Diversity transceiver for a wireless local area network

A method that includes wirelessly receiving a signal, and detecting a start of packet (SOP) for a packet that conforms to a wireless networking standard. The detecting from the received signal uses at least one SOP detection criterion. In the case an SOP is detected, the method further includes determining a plurality of metrics from the received signal, and using at least two of the plurality of metrics to determine an initial timing for a received packet. Different versions combine the metrics in different ways to determine the initial timing. Also an apparatus that includes a radio receiver to receive a signal and output a received signal, and an SOP detector coupled to the radio receiver to detect a start of packet (SOP) from a received signal using at least one SOP detection criterion for a packet that conforms to a wireless networking standard. The apparatus further includes a processing circuit coupled to the radio receiver to determine a plurality of metrics from the received signal, and a initial time determining circuit coupled to the SOP detector and the processing circuit. In the case an SOP is detected, the initial time determining circuit uses at least two of the plurality of metrics to determine an initial timing for a received packet.

An interleaver and interleaving method each includes two stages, and is useful in coded orthogonal frequency division multiplexed (COFDM) wireless local area networks. A first stage performs a first block permutation and a second stage performs bit order permutation to effectuate a second group permutation. A corresponding de-interleaver does just the opposite at the receiver. A double-buffer version includes writing data into one memory block in a first order while reading data from the second block in a second order, with the first and second orders selected to effectuate the first block permutation.

Interleaver, deinterleaver, interleaving method, and deinterleaving method for OFDM data

In an OFDM radio receiver for a wireless packet network, an apparatus to equalize a presently received OFDM signal containing subcarriers using an equalizing signal formed from the past symbols of subcarriers. The apparatus includes a subtractor to subtract the equalizing signal from the present signal, a DFT device to convert to subcarriers, a forward processor to correct the subcarriers for the channel and phase errors, a decision device to make decisions for the subcarriers, a reverse processor to corrupt the decision-based subcarriers' phase in the same manner as the forward processor corrects the subcarrier's phase, an inverse DFT device to form a time signal from the reverse processed subcarriers, and a feedback filter to generate the equalizing signal. The feedback filter's impulse response is directly calculated from an estimate of the channel response.

Decision feedback equalizer in an OFDM WLAN receiver

A method of determining a geographical location of an asset tracking device, includes searching, by the asset tracking device, for available location determination schemes at the geographical location, selecting one of the available location determination schemes, and determining coordinates of the geographical location using the selected location determination scheme. Some embodiments also include making a decision based, at least in part, upon the geographical location coordinates determined by using the selected location determination scheme. Some embodiments include transmitting a location message, the location message including the coordinates of the geographical location and an indication as to the selected location determination scheme.

Location determination method and system for asset tracking devices

A digital AGC system for burst operation, particularly suited for receiving packets in a wireless local area network. One embodiment includes a log detector that provides a signal strength measure, called the received signal strength indication (RSSI) over a wide dynamic range. The AGC system includes estimating the power in a received signal by averaging the log of the signal power. The Start of Packet detection avoids using the radio receiver's main analog to digital converters to preserve power.

Automatic gain control and low power start-of-packet detection for a wireless LAN receiver

Devices, such as tracking devices, cooperate with one another to establish the routing necessary for a relay network in which a device having power-efficient and data-reliable communication with an access portal, operates to relay messages from devices which do not have an acceptable communication path to and/or from the access portal. In one aspect of the present invention, a plurality of devices synchronously determine whether an acceptable communication path can be established between themselves and one or more access portals by measuring the signal strength of an access portal beacon. In another aspect of the present invention, one or more devices, which have determined that an acceptable communication path can be established between themselves and an access portal, transmit information regarding their availability to relay messages on behalf of devices which have determined that an acceptable communication path cannot be established between themselves and an access portal.

Methods and apparatus of meshing and hierarchy establishment for tracking devices

A wireless computer data network includes several untethered mobile units that make ad-hoc data connections with an Internet-connected base station using the IEEE-802.11a standard. Each unit includes a radio transceiver fully integrated on a single semiconductor chip. The receiver portion is a double-conversion superheterodyne type, and shares the same intermediate and local oscillator frequencies with a two-stage up-conversion transmitter. Two on-chip synthesizers that each include a voltage-controlled oscillator and phase-locked loop can be operated independently for each conversion stage, or operated in offset mode. External reference frequencies can be injected for voltage-controlled oscillator and phase-locked loop testing, chip characterization, and automatic compensation modeling. Each mobile and base unit can be outfitted with transmit/receive antenna transfer switches, RF-power amplifiers, and low-noise receiver amplifiers to increase operating range.

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Hunters Hill, Australia

John D O'Sullivan