Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 the particular subcarrier's one or more immediate neighbors to take advantage of correlation that may exist between the particular subcarrier's channel and the channels of that subcarrier's one or more immediate neighbors.

Abstract: 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.

Abstract: 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.

Abstract: The present invention discloses a wireless LAN, a peer-to-peer wireless LAN, a wireless transceiver and a method of transmitting data, all of which are capable of operating at frequencies in excess of 10 GHz and in multipath transmission environments. This is achieved by a combination of techniques which enable adequate performance in the presence of multipath transmission paths where the reciprocal of the information bit rate of the transmission is short relative to the time delay differences between significant ones of the multipath transmission paths. In the LANs the mobile transceivers are each connected to, and powered by, a corresponding portable electronic device with computational ability.

Abstract: The elements of a transform processing circuit are switchable to change the order of data in a data stream and/or to perform a fast Fourier transform (FFT) or inverse fast Fourier transform (IFFT) on the data stream. Each arithmetic circuit element performs an M-point butterfly operation on complex sample points and includes an adder/subtractor and a serial memory capable of storing M/2 sample points. Each multiplication unit performs an n-point complex twiddle factor operation on its input. The conjugator units conjugate inputted sample points. All circuit elements are connected to buses by switches. These connections are switchable so that in one switch state data input at left terminal flows to right terminal and in another state data input at right terminal flows to left terminal. The state of the bus switches also determines whether the circuit performs a FFT, an IFFT, or a bit reversal operation on input data.