Abstract: An orthogonal frequency division multiplex (OFDM) transmitter may adaptively load each sub-carrier, buffering less than an OFDM frame in order to reduce hardware requirements and latency. The transmitter may use feedback information from the receiver regarding the quality of the sub-carriers. In addition, combining repetition and puncturing to achieve a desired date rate per class further reduces hardware by simplifying or even eliminating an interleaver. Additional mitigation and even performance enhancement techniques are incorporated to address inter-class boundaries within an OFDM frame, such as introducing transition classes. Channel state information may be reported in various formats including full bitmap, changed subchannels, and reported bad subchannels.

Abstract: In embodiments, an adaptive tone erasure technique is applied to orthogonal frequency division multiplexing (OFDM) communications, such as ECMA-368 standard ultra-wideband (UWB) communications. A transmitter obtains jammed sub-carrier information and calculates an erasure mask. The jammed sub-carriers are nulled before transmitting to a receiver. In accordance with the erasure mask, bits falling on the jammed sub-carriers are replaced by erasure bits before interleaving, keeping the interleaver block size constant notwithstanding variations in the number of the jammed sub-carriers. The receiver also obtains the jammed sub-carrier information and the erasure mask. After the receiver deinterleaves the constant size blocks, it decodes the data without the erasure bits. The transmitter may detect the jammed sub-carriers itself, or obtain the information from the receiver. The receiver similarly may detect the jammed sub-carriers itself, or obtain the information from the transmitter.

Abstract: Techniques for rotating and transmitting multidimensional constellations are disclosed. A method for rotating a multidimensional constellation may include constructing a first rotation matrix, constructing a second rotation matrix, applying orthogonality constraints to the first and second rotation matrices; selecting an optimizing rotation matrix from the first and second rotation matrices; and rotating the multidimensional constellation using the optimizing rotation matrix. Constructing the first rotation matrix and second rotation matrices may include constructing a first column that includes first matrix elements based on the number of axes in the multidimensional constellation, and additional columns that include permutations of the first matrix elements.

Abstract: A method for performing carrier frequency offset estimation and frame synchronization is disclosed herein. In one approach, the method includes performing a first level frequency discrimination on at least one estimated channel tap to generate a frequency discriminated value; estimating a phase error from the frequency discriminated value; and, determining a predetermined frame synchronization pattern from the estimated phase error. A computer program product having code and a wireless communications apparatus for performing the method are also described herein.

Abstract: A method for performing symbol timing estimation is disclosed herein. In one approach, the method includes defining a search space in a plurality of estimated magnitudes of channel taps; defining a search window in the search space; and locating a symbol timing estimate index in the search space corresponding to a maximum value of an energy of the plurality of estimated magnitudes of channel taps within the search window. A computer program product having code and a wireless communications apparatus for performing the method are also described herein.

Abstract: An apparatus for detecting an OFDM symbol encoded with a transmitted sequence including a filter having coefficients based on a simplified version of the transmitted sequence is disclosed. A computer program product having code and a wireless communications apparatus for performing the method are also described herein.