Abstract: An automatic gain control (AGC) circuit and method for performing AGC for an orthogonal frequency-division multiplexing (OFDM) receiver measures signal power of input digital signals that are derived from incoming data frames with preambles to produce gain change signals when the signal power differs from a reference target power level. The gain of an amplifier of the OFDM receiver is changed in response to the gain change signals until a preamble of the data frames is detected for the first time. The gain of the amplifier of the OFDM receiver is further changed in response to the gain change signals, after the preamble is detected, only during periods when the preambles of the data frames are being processed by the OFDM receiver such that the gain of the amplifier is not changed during periods when other portions of the data frames are being processed by the OFDM receiver.

Abstract: An OFDM-based device and method for performing synchronization utilizes a time-domain preamble of an incoming OFDM-based signal to compute an estimated fine frequency offset. The computation of the estimated fine frequency offset involves multiplying values of the time-domain preamble with conjugates of corresponding values of a selected base station time-domain preamble, averaging the resulting multiplied values in predefined segments and self-correlating the resulting averaged values to derive a self-correlation value, which is used to compute the estimated fine frequency offset.

Abstract: A device and method for performing a channel profile estimation for an OFDM-based wireless communication system uses an averaged frequency coherence metric to select a particular channel profile, which is a current channel profile estimate. The averaged frequency coherence metric is derived using correlations between pilot subcarriers of an OFDM-based signal at predefined subcarrier locations for multiple frames of the OFDM-based signal. The selected channel profile may be used for channel estimation, as well as for link adaptation, to improve the performance of these processes.

Abstract: A device and method for performing a channel estimation for an OFDM-based wireless communication system using sparsely spaced pilot subcarriers estimates missing pilot subcarriers in an interpolation window using pilot subcarriers that are outside of the interpolation window to produce estimated pilot subcarriers for the interpolation window. The pilot subcarriers in the interpolation window and the estimated pilot subcarrier are used to compute pilot channel estimates for the interpolation window, which are then used to derive data channel estimates for the interpolation window.

Abstract: A soft-bit de-mapping device and method of generating soft bits for decoding quantizes a log-likelihood ratio (LLR) value for a received value using functions bits and channel parameter bits to generate the soft bits. The function bits are generated by quantizing an LLR function for the received value, which includes modifying an original curve of the LLR function to a modified curve such that a segment of the original curve with the lowest slope is protected in the modified curve for a fixed equal quantization step-size. The channel parameter bits are generated by quantizing a channel parameter for the received value to generate channel.

Abstract: A method for reducing power consumption in a multi-user digital communication system and mobile station employing the method adjusts receive and transmit mode durations of the mobile device using downlink and uplink allocations from a base station of the system, as well as other factors.

Abstract: An Orthogonal Frequency Division Multiple Access (OFDMA) device and method of correcting frequency offset in OFDMA signals computes an estimated frequency offset, which is used for producing a frequency offset-compensated mixer signal using a reference clock signal. The frequency offset-compensated mixer signal is used to produce a digital down-converted signal from an incoming OFDMA signal. The digital down-converted signal is digitally corrected for sampling errors using the estimated frequency offset.

Abstract: An apparatus and method for transmitting outgoing data uses data descriptors for multiple sets of contiguous data blocks stored in buffers. When new sets of contiguous data blocks are created due to acknowledgement signals for particular data blocks of the multiple sets of contiguous data blocks, new data descriptors are generated for some of the new sets of contiguous data blocks. These new data descriptors are placed in spaces in the buffers where the particular data blocks were originally stored.

Abstract: A device and method of performing channel estimation for an OFDM-based wireless communication system performs a Least Square interpolation with a statistical channel profile consideration on pilot channel estimates to derive data channel estimates at data subcarrier locations.

Abstract: A device and method for performing channel estimation for an OFDM-based wireless communication system modifies pilot subcarrier spacing to use a set of interpolation coefficients associated with a different pilot subcarrier spacing.