Abstract: Various embodiments are described for a trained data transmission for communication systems.

Abstract: Various embodiments are described to select or adjust transmission parameters.

Abstract: An apparatus may include an orthogonal frequency division multiplexing (OFDM) physical layer interface. An adaptive subcarrier demodulator or an adaptive subcarrier modulator may be coupled to the OFDM physical layer interface to implement adaptive bit loading (ABL). A decoder or an encoder may be coupled to the adaptive subcarrier demodulator or to the adaptive subcarrier modulator to implement low density parity checking.

Abstract: Briefly, in accordance with one embodiment of the invention, a wireless network may include transmitters that may transmit information over a channel. the transmitter may also transmit channel side information over the channel. Further, the transmitters may adjust when channel side information is transmitted in accordance with the channel coherence time.

Abstract: A wireless communication device communicates orthogonal frequency division multiplexing (OFDM) signals comprised of orthogonal subcarriers within an available spectrum. In-band interference, noise and channel effects may be measured for the subcarrier frequencies and a modulation order is selected on a per subcarrier basis to compensate for channel effects and in-band interference. Accordingly, the subcarriers may be configured to operate at a maximum communication rate allowing the channel to approach its “water-filling capacity”. In one embodiment, an access point may select modulation orders on a per subcarrier basis for upstream communications received from the wireless communication devices. In another embodiment, the wireless communication devices may select modulation orders on a per subcarrier basis for downstream communications received from the access point. Forward error correction (FEC) code rates and interleaving may be adjusted to the per subcarrier modulation selections.

Abstract: A technique includes receiving a signal that indicates a modulated symbol during a given time slice of the signal. Sliding window frequency transformations of the signal are performed, and each sliding window transformation is associated with a different time interval of the signal. One of the time intervals is selected to correspond to the time slice. The result of the frequency transformation associated with the selected time interval is used to obtain an indication of the demodulated symbol.

Abstract: A computationally efficient channel estimation technique for use within an orthogonal frequency division multiplexing (OFDM) communication system determines coefficients of a channel transfer function by calculating the dot products of a pilot vector and a plurality of interpolation vectors. One dot product is preferably calculated for each subcarrier of interest within the system. The pilot vector is extracted from an OFDM symbol received from a communication channel. In a preferred approach, a number of interpolation vectors are precalculated and stored within a communication device for subsequent use during channel estimation and equalization operations. The technique is highly flexible and can be implemented using, for example, a variable user block size or a variable pilot vector size.

Abstract: A technique includes basing a discrete frequency transformation on the number of subcarriers in a predetermined set of subcarriers. One or more subcarriers of the set are assigned to modulate data, and the remaining subcarriers of the set are not assigned to modulate the data. The discrete frequency transformation is performed on the data to modulate the data, and mathematical operations that are associated with the subcarriers not assigned to modulate the data are excluded from the transformation.

Abstract: A superatmospheric combustion apparatus and a method of operating such an apparatus include providing a superatmospheric combustion device having a lean gas chamber, a combustor, a heat recovery section, and an exhaust, feeding lean gas to the lean gas chamber, providing a heat sink/pressure equalization chamber and a preheated air chamber within the combustion device, feeding pressurized ambient air to the heat sink/pressure equalization chamber, feeding preheated air to the preheated air chamber, exchanging heat from the lean gas chamber, the preheated air chamber, and the combustor to the pressurized ambient air in the heat sink/pressure equalization chamber, feeding the lean gas from the lean gas chamber to the combustor, feeding the preheated air from the preheated air chamber to the combustor, and combusting the lean gas and the preheated air in the combustor at superatmospheric pressure.