An apparatus, method, computer readable medium, and system are provided to determine whether a non-linear signal impairment is present in a network communication channel. For instance, a computing device may transmit equalization coefficients to a user device to modify future signals generated by the user device. If the equalization coefficients are unable to reduce a signal impairment, the signal impairment may be a non-linear signal impairment. The computing device may generate symbol placements based on signals received from the user device and transmit status messages.

The present invention relates to precoding and feedback channel information in wireless communication system. A method includes receiving a first Precoding Matrix Index (PMI) and a second PMI from a terminal; mapping one or two codewords into layers; precoding symbols mapped into the layers using a first precoding matrix derived from the first PMI and a second precoding matrix derived from the second PMI; and transmitting the precoded symbols to the terminal, wherein the reception of the first PMI is less frequent than the reception of the second PMI.

The present invention relates to precoding and feedback channel information in wireless communication system. A method includes receiving a first Precoding Matrix Index (PMI) and a second PMI from a terminal; mapping one or two codewords into layers; precoding symbols mapped into the layers using a first precoding matrix derived from the first PMI and a second precoding matrix derived from the second PMI; and transmitting the precoded symbols to the terminal, wherein the reception of the first PMI is less frequent than the reception of the second PMI.

A communication system provided with first generator for generating an error signal based on an ideal signal generated based on an output signal from a decider for performing a hard decision, and an input signal to the decider; second generator for generating a compensation coefficient for compensating for non-linear distortion included in a modulation signal, which is a transmission signal, based on the error signal; and compensator for compensating for the non-linear distortion based on the compensation coefficient.

Channel data for a plurality of OFDM tones for one or more spatial or space-time streams are determined. A plurality of angle values associated with the one or more spatial or space-time streams and the one or more OFDM tones of the plurality of OFDM tones are determined. For each of the one or more spatial or space time streams, a per-tone signal to noise ratio (PT-SNR) associated with one or more OFDM tone of the plurality of OFDM tones is determined, and an average signal to noise ratio (avg-SNR) is determined by averaging signal to noise ratio (SNR) values corresponding to one or more OFDM tones of the plurality of OFDM tones. A feedback report is generated to include at least i) the plurality of angle values, ii) the PT-SNRs, and iii) the avg-SNR.

An apparatus, method, computer readable medium, and system are provided to determine whether a non-linear signal impairment is present in a network communication channel. For instance, a computing device may transmit equalization coefficients to a user device to modify future signals generated by the user device. If the equalization coefficients are unable to reduce a signal impairment, the signal impairment may be a non-linear signal impairment. The computing device may generate symbol placements based on signals received from the user device and transmit status messages.

A jones matrix is obtained using coefficients of an equalizer; a parameter of the jones matrix is obtained; a coefficient of an X axis polarization state or a Y axis polarization state in the coefficients is adjusted using the parameter of the jones matrix when the coefficients have singularity characteristics, or energy corresponding to each coefficient of X or Y axis polarization state under each order of a filter in the equalizer is determined using two coefficients of an X or Y axis polarization state in the equalizer coefficients; and a central position of a coefficient tap of X or Y axis polarization state of the equalizer is adjusted using the energy corresponding to each coefficient of X or Y axis polarization state under each order of the filter when the coefficient tap of the X axis or Y axis polarization state of the equalizer deviates from the central position.

All data symbols used in data transmission of a modulated signal are precoded by hopping between precoding matrices so that the precoding matrix used to precode each data symbol and the precoding matrices used to precode data symbols that are adjacent to the data symbol in the frequency domain and the time domain all differ. A modulated signal with such data symbols arranged therein is transmitted.

For example in case of an OFDM multicarrier transmission system the transmission characteristics of subcarriers of a multicarrier transmission system using a plurality of antenna elements (3, 3) can be adjusted. Particularly the power and the phase of the subcarriers can be adapted. To this object the subcarrier frequency channel (2, 2) characteristics of the multicarrier transmission are detected (11, 11) at the side of the transmitter (3). The power of each subcarrier is then distributed by a weighting unit (14, 14). The subcarriers can be further pre-equalized (1, 1) by dividing the subcarrier signal respectively by the sum of the squared magnitude of the frequency channel characteristics of all subcarrier signals or a frequency characteristic of the selected antenna element (3, 3).

One embodiment provides a network controller. The network controller includes a modulation module. The modulation module includes a high rate (HR) bit sequence generator configured to generate a first high rate bit sequence, encoder circuitry configured to encode a first low rate bit stream, the first low rate bit stream comprising backchannel information, and modulation circuitry configured to modulate the encoded first low rate bit stream onto the first high rate bit sequence. The network controller further includes transmit circuitry configured to transmit the modulated first HR bit sequence to a link partner during a link initialization period.