Abstract: Multiple-input-multiple-output (MIMO) timing recovery. A novel approach is presented to perform timing recovery when processing the multiple received signals within a MIMO communication device. This may be implemented for a singular received signal, or a plurality of received signal streams. In addition, this timing recovery may be performed in conjunction with carrier detection to provide more robust performance. Alternatively, indicia and/or signals corresponding to carrier detection of these signals may be provided to timing recovery functionality from carrier detection functionality external to the timing recovery functionality. Certain processing and analysis is performed on a modified correlation function that is generated using samples of moving windows that pass over symbols of a packet.

Abstract: Carrier detection applicable for SISO, MIMO, MISO, and SIMO communications. A novel approach is presented to perform carrier detection for a signal found in any of a wide variety of communication systems including single-input-multiple-output (SISO), multiple-input-multiple-output (MIMO), multiple-input-single-output (MISO) single-input-multiple-output (SIMO), communication systems. This novel approach to performing carrier detection is more robust than those approaches existent in the art. By employing normalization with respect to power in determined a modified correlation function, there is less susceptibility to false detects. Also, this approach is quite robust to any circuitry DC offsets that may undesirably exist within a communication device that undergoes operational changes due to a variety of factors including environmental perturbations and/or changes in processing circuitry within the communication device (e.g., changes in gain control).

Abstract: A method is described for correcting sampling frequency offset (SFO) of a data packet in a communications system where carrier frequency (fc) and sampling frequency (fs) are driven by a common clock source. The method comprises, for each lth symbol in the data packet, estimating carrier frequency offset (CFO) in a received data packet. From the CFO estimate, an SFO estimate is derived, wherein the SFO is approximately equal to fs multiplied by said CFO estimate, and divided by fc. An SFO phase correction is generated according to the SFO estimate for each kth tone in a data stream. The SFO phase correction is then applied to each received data stream.

Abstract: A method is disclosed for correcting carrier frequency offset (CFO) in a received data packet that includes one or more M data streams. The data packet has a payload portion preceded by a preamble portion, the payload portion having a plurality of data symbols (L) each of which include a plurality of data tones (K). The method comprises, making a per-stream preamble CFO estimate for each data stream by correlating repeated preamble portions that precede the data packet. The per-stream preamble CFO estimates are weighted and averaged to obtain a single preamble CFO estimate. Any CFO in each received data stream is then corrected according to the preamble CFO estimate. Additionally, for an lth data symbol in a data packet, a per-tone CFO estimate is derived and successively averaged over frequency (tones), time (symbols) and space (data steams) to derive data CFO estimate pdata. Any CFO in each received data stream may be corrected according to the data CFO estimate, and/or the preamble CFO estimate.

Abstract: The present invention relates to a DC offset canceling circuit. In one aspect of the invention, a DC offset canceling circuit with independently configurable gain and roll-off frequency is provided. In one embodiment of the present invention, the DC offset canceling circuit is used in the receive path of a down-conversion wireless receiver. In another aspect of the invention, a method for independently varying the gain and the roll-off frequency of the DC offset canceling circuit is provided. In one embodiment, the method is used to independently operate a gain control scheme and a DC offset cancellation strategy in a DC canceling circuit.

Abstract: The present invention provides a method for carrier detection associated with the receipt of MIMO RF packet communications. This involves receiving multiple MIMO RF packet communications with multiple receiver pathways, wherein the RF packet communications each comprise a preamble and data. The RF packet communications are sampled by a carrier detector before, during or after conversion to baseband. The carrier detectors are used to produce a set of carrier detection metrics for each reception pathway. These carrier detection metrics may be combined arithmetically with those of other reception pathways to produce a multi-reception pathway carrier detect. Alternatively, these carrier detection metrics can be processed to produce a logical decision or binary detection signal value associated with each reception pathway, which is then logically combined with the logical decisions of other reception pathways to produce a multi-reception pathway carrier detect.

Abstract: The present invention provides a method for automated gain control associated with the receipt of multiple input multiple output (MIMO) radio frequency (RF) packet communications. This involves receiving multiple MIMO RF packet communications with multiple receiver pathways, wherein the RF packet communications each comprise a preamble and data. A gain is applied to the RF packet communication with a programmable gain amplifier operable to adjust the gain based on received control signals from the baseband processing module. The RF packet communication(s) are down converted to produce a baseband packet communication. This communication in then converted from an analog signal to a digital signal. The digital signal is sampled for a valid preamble. The results of the sampled digital signal are used to produce a control signals to the programmable gain amplifier based on the sampling of the digital signal and upstream analog signals associated with the RF packet communication.

Abstract: A network device for transmitting a set of known pilot symbols in a communications system utilizing a plurality of transmit sources. The network device includes generating means for generating the set of known pilot symbols to be transmitted for each of the plurality of transmit sources and inserting means for inserting pilot symbols for each of the plurality of transmit sources. The network device also includes creating means for creating a near to full orthogonal matrix over time and frequency using the fewest number of pilot symbols. The pilot symbols are used for at least one of channel, frequency, and phase tracking at a receiving station.

Abstract: A network device for cancelling spurs without affecting an incoming signal. The network device includes an estimator for estimating amplitude and phase of a spur over a predetermined period of time. The network device also includes processing means for freezing further estimation of the amplitude and phase of the spur, for cancelling for an estimated spur and for allowing incoming packets. The network device further includes subtracting means for subtracting the estimated spur from an incoming packet. The estimated spur is subtracted from the incoming packet without affecting incoming signals that are not part of the estimated spur.

Abstract: A method for payload-based channel estimation of a wireless channel begins by receiving a frame via the wireless communication channel. The frame includes a training sequence, a frame information section, and a plurality of time sequential data payload sections. As the frame is being received, the method continues by determining a channel estimation based on the training sequence. The method continues as the frame is being received by determining a channel estimation of a data payload section of the plurality of time sequential data payload sections to produce a payload channel estimation. The method continues as the frame is being received by updating the channel estimation based on the payload channel estimation to produce an updated channel estimation.

Abstract: A method of calibrating the slope of a received signal strength indicator circuit is disclosed. An embodiment of the present invention may adjust for manufacturing process, power supply voltage, and ambient temperature variations by periodically calibrating the measurement of receive signal strength in a RF communication device, using the transmitter of the device. Various embodiments of the present invention may use a look-up table to convert unadjusted receive signal strength values to adjusted receive signal strength values, may adjust the operation of the circuitry generating an indication of receive signal strength, and may adjust thresholds in executable code used to manage the operation of the radio frequency communication system.