Abstract:
Bei einem Verfahren zur Kompensation eines Phasenfehlers in einem Empfangs- und/oder Sendesystem mit I- und Q-Verarbeitungszweigen werden in einer Berechnungsstufe (PC) eines digitalen Signalverarbeitungsabschnitts (10') der I- und Q-Signalverarbeitungszweige phasenkorrigierte I- und Q-Signalkomponenten berechnet.
Abstract:
A cross product is determined for a received signal. A dot product is also determined for the received signal. If the cross product is greater than a predetermined threshold, the cross product is decremented by the product of the dot product multiplied by a constant value. If the cross product is greater than or equal to the predetermined threshold, the cross product is incremented by the product of the dot product multiplied by the constant value. The incrementing or decrementing is continued until the frequency error approaches a minimum value.
Abstract:
A method is disclosed to distinguish a first type of control channel from a second type of control channel. The method includes steps of (a) transmitting a carrier of the first type of control channel so as to include a first symbol sequence that results, when demodulated, in a sine wave having a frequency with a first offset from the carrier; (b) transmitting a carrier of the second type of control channel so as to include a second symbol sequence that results, when demodulated, in a sine wave having a frequency with a second offset from the carrier; and (c) demodulating a received carrier and detecting whether the carrier includes the first type of control channel of the second type of control channel. In the preferred embodiment of this invention the first symbol sequence is an all zeroes sequence, and the second type of symbol sequence is an alternating ones and zeroes sequence, which results in the first offset being a positive offset, and the second offset being a negative offset. In a most preferred embodiment the first offset is +67.7 kHz, and the second offset is -67.7 kHz. The step of demodulating includes a step of multiplying an I/Q representation of the received symbol sequence by 1-j, -1j, 1-j,..., and by 1j, -1-j, 1j,...
Abstract:
A receiver and a multi-symbol-differential-detection (MSDD) module, the MSDD may include an input node for receiving an input signal having a noisy phase; a summation and rotation unit; and an output unit; wherein the output unit is arranged to output an output signal and a normalized output signal; wherein the output signal represents the input signal but has a reconstructed phase; wherein the summation and rotation unit is arranged to receive the input signal and the output signal and to provide a reference signal that reflects a weighted sum of phase rotated and delayed previously received input signals; wherein the output unit comprises a phase difference calculator, a slicer, a delay unit and a normalizer; wherein the phase difference calculator is arranged to generate a difference signal indicative of a phase difference between the reference signal and the input signal; wherein the slicer and the delay unit are arranged to generate the output signal by slicing the difference signal to provide a sliced signal and by delaying the sliced signal; and wherein the normalizer is arranged to normalize the output signal to provide the normalized output signal.
Abstract:
A method and apparatus perform I/Q imbalance estimation and compensation using synchronization signals in LTE systems. Primary and secondary synchronization signals (P-SCH and S-SCH), which carry synchronization information, are embedded in each LTE frame, and are used for receiver I/Q imbalance estimation. Additionally, the performance may be significantly improved by optimally selecting the training data in I/Q imbalance estimation.
Abstract:
A wireless communication system receiver compensates a received signal containing an IQ gain imbalance prior to performing frequency correction (32). The IQ imbalance in the signal is estimated after frequency correction, providing an IQ gain imbalance estimate (?n) for subsequent IQ gain imbalance compensation. The IQ gain imbalance estimation includes formulating (38) a plurality of hypotheses (Zt) of phase error between I and Q signal components, and taking as the actual phase error the hypothesis that yields the maximum power ratio between I and Q signal components. The maximum power ratio is differentiated with the respect to the IQ imbalance estimate. The IQ gain imbalance estimate is updated as a function of its prior value(s), the maximum power ratio, and the derivative of the maximum power ratio.
Abstract:
A method for analog front-end impairment compensation in OFDM Multi- Carrier Systems based on adaptive blind-source-separation techniques, which may be used to improve the IQ phase and gain mismatches in zero-IF type as well as low-IF type receivers. The method comprises resolving a received signal into its component carrier signals and demixing the I and Q channels of each resolved carrier in a demixing stage. In the demixing, signal components of a resolved carrier are input to first and second cross coupled adaptive filters, whose coefficients are updated by the outputs of the demixing stage.