Techniques for peak-to-average power ratio (PAPR) reduction are described. Wireless devices may use one or more PAPR shaping resources, such as expanded bandwidth and/or pulse-shaping filtering, for shaping a signal to reduce PAPR. For example, expanded bandwidth may be utilized for adding a cyclic affix (CA), such as may comprise a cyclic prefix (CP), cyclic suffix (CS), etc., and combinations thereof, to a frequency domain data signal to provide a CP augmented frequency domain data signal used to generate a reduced PAPR time domain data signal. Additionally or alternatively, pulse-shaping filtering may be applied to a frequency domain signal to provide a pulse-shaped frequency domain data signal used to generate a reduced PAPR time domain data signal. Other aspects and features are also claimed and described.

Embodiments of the present disclosure relate to a method and system to generate a waveform in a communication network. The transmitter receives an input data and transmit a generated waveform to another communication system. The input data is spread with a spread code to generate a spread data and rotated using a constellation rotation operation to produce a rotated data. The rotated data is then precoded using precoding filter to produce a precoded data, and transformed into DFT output data using DFT operation. The DFT output data is then mapped with subcarriers to generate the sub-carrier mapped DFT data and modulated using Orthogonal Frequency Division Multiplexing (OFDM) modulation to generate the waveform with low PAPR.

A method for wireless communication includes allocating a transmission bandwidth for transmission to a user equipment (UE). The method further includes determining if the allocated transmission bandwidth is less than or equal to a maximum estimated BW.sub.DPD. The maximum estimated BW.sub.DPD is the maximum estimated signal bandwidth that a transmitter is configured to digitally pre-distort. The method also includes digitally pre-distorting transmit signals and transmitting the digitally pre-distorted transmit signals to the UE if the allocated transmission bandwidth is less than or equal to the maximum estimated BW.sub.DPD. The method also includes transmitting to the UE without digitally pre-distorting the signals if the allocated transmission bandwidth is not less than or equal to the maximum estimated BW.sub.DPD. The method also includes applying digital crest factor reduction to the transmit signals if the allocated transmission bandwidth is less than or equal to the maximum estimated BW.sub.CFR.

A transmitter includes: a frame generator configured to generate a frame including a frame starting symbol, at least one data symbol and a frame closing symbol; a pilot and reserved tone inserter configured to insert pilots and reserved tones in at least one of the frame starting symbol, the data symbol and the frame closing symbol such that positions of the reserved tones do not overlap positions of the pilots in the at least one of the frame starting symbol, the data symbol and the frame closing symbol; and a transmitter configured to transmit the frame in which the pilots and the reserved tones are inserted, wherein the reserved tones are not used to transmit data in the frame.

A hybrid multi-layer method for decomposing of a source signal to a plurality of decomposed signals that can be used to collectively represent the source signal or recover the source signal. An example embodiment is a method that includes multi-layer (or multi-stage) signal decomposition to generate constant envelope signals without impact on the original signal. In an example embodiment, the method includes signal decomposition to maintain constant envelope properties and limit bandwidth expansion from the signal decomposition. The method includes decomposing a source signal into two first-stage decomposed signals that each have a constant envelope amplitude value. The method further includes iteratively decomposing each of the constant envelope signals into further-stage decomposed signals based on a threshold amplitude value at each iteration. The further-stage decomposed signals have a constant envelope with an envelope amplitude value in dependence of the threshold amplitude value at each iteration.

A hybrid multi-layer method for decomposing of a source signal to a plurality of decomposed signals that can be used to collectively represent the source signal or recover the source signal. An example embodiment is a method that includes multi-layer (or multi-stage) signal decomposition to generate constant envelope signals without impact on the original signal. In an example embodiment, the method includes signal decomposition to maintain constant envelope properties and limit bandwidth expansion from the signal decomposition. The method includes decomposing a source signal into two first-stage decomposed signals that each have a constant envelope amplitude value. The method further includes iteratively decomposing each of the constant envelope signals into further-stage decomposed signals based on a threshold amplitude value at each iteration. The further-stage decomposed signals have a constant envelope with an envelope amplitude value in dependence of the threshold amplitude value at each iteration.

An apparatus and method for performing crest factor reduction (CFR). A peak detection circuit detects peaks from input signal samples based on a first threshold. The first threshold is higher than a second threshold that is determined based on a target peak-to-average power ratio (PAPR). A gain computation circuit determines a gain factor for at least one detected peak. A scaled cancellation pulse generation circuit generates a scaled cancellation pulse for the at least one detected peak based on the gain factor. A combiner circuit combines the scaled cancellation pulse with the input signal samples to generate an output signal. A hard clipping circuit may compress the output signal based on the second threshold. The first threshold is set slightly higher than the second threshold.

A correlation apparatus including a sequence generator configured to generate a non-repeating preamble sequence which changes during each of a plurality of time epochs. The correlation apparatus includes a fallthrough correlator having a tapped delay line for receiving a set of complex-valued samples of a received signal. Each of a plurality of complex multipliers of the correlator is coupled to one of the delay line taps. Each multiplier multiplies, during one of the plurality of time epochs, one of the complex-valued samples of the received signal by one of a plurality of matched filter coefficients corresponding to the preamble sequence. A summation module includes a plurality of adders where a last of the plurality of adders outputs a correlation signal. A peak value of the correlation signals exceeds a threshold value when a sufficient correlation exists between the received signal and the values of the preamble sequence.

A signal receiver for receiving a HOPS-based communications signal includes a seed calculator configured to produce a series of seed vectors generated from a corresponding series of sets of key values. A sequence generator provides a series of internally generated sequences using the series of seed vectors. A fallthrough correlator produces a series of correlation values by correlating samples of a received signal and samples of the internally generated sequences. The spreading sequences are used by a transmitter to generate a transmit signal subsequently received as the received signal. A peak detector is configured to generate a trigger signal upon determining that at least one of the correlation values exceeds a threshold value. At least one of a plurality of demodulator chains is selected in response to the trigger signal and used to demodulate the received signal in order to recover data values carried by the received signal.

A transmitter includes: a frame generator configured to generate a frame including a frame starting symbol, at least one data symbol and a frame closing symbol; a pilot and reserved tone inserter configured to insert pilots and reserved tones in at least one of the frame starting symbol, the data symbol and the frame closing symbol such that positions of the reserved tones do not overlap positions of the pilots in the at least one of the frame starting symbol, the data symbol and the frame closing symbol; and a transmitter configured to transmit the frame in which the pilots and the reserved tones are inserted, wherein the reserved tones are not used to transmit data in the frame.