Certain aspects of the present disclosure generally relate to wireless communications. In some aspects, a wireless device reduces a peak-to-average power ratio (PAPR) of a discrete-time orthogonal frequency division multiplexing (OFDM) transmission by selecting a signal with low PAPR from a set of candidate discrete-time OFDM signals. The wireless device may generate a partial-update discrete-time OFDM signal by performing a sparse transform operation on a base data symbol sequence, and then linearly combine the partial-update discrete-time OFDM signal with a base discrete-time OFDM signal to produce an updated discrete-time OFDM signal, which is added to the set of candidate discrete-time OFDM signals. Numerous other aspects are provided.

Certain aspects of the present disclosure generally relate to wireless communications. In some aspects, a wireless device reduces a peak-to-average power ratio (PAPR) of a discrete-time orthogonal frequency division multiplexing (OFDM) transmission by selecting a signal with low PAPR from a set of candidate discrete-time OFDM signals. The wireless device may generate a partial-update discrete-time OFDM signal by performing a sparse transform operation on a base data symbol sequence, and then linearly combine the partial-update discrete-time OFDM signal with a base discrete-time OFDM signal to produce an updated discrete-time OFDM signal, which is added to the set of candidate discrete-time OFDM signals. Numerous other aspects are provided.

The present invention relates to a wavelet bandpass sampling method, with low aliasing and a corresponding device. The analogue signal to sample is correlated with a sequence of wavelets succeeding each other with a rate f.sub.p of which the positions in the sequence are temporally modulated from arguments of a CAZAC sequence, notably a Zadoff-Chu sequence. The correlation results are next sampled at a frequency f.sub.sf.sub.p and digitally converted to provide a compressed representation of the signal. The temporal modulation of the positions of the wavelets makes it possible to obtain incoherent aliasing of the correlation signal in the sampling band and thereby to reduce aliasing.

The present invention provides a transmission method which generates and sends a transmission signal generated from a multiplexing OFDM signal or a multiplexing wavelet-OFDM signal employing a multiplexing-spread chip sequence in which a chip of a code sequence for spread and a code sequence for combination, and a chip of a code sequence for localization are multiplied and multiplexed, and a receiving method which makes a high SN ratio improvement rate possible by converting the received signal to a frequency domain to acquire the multiplexing-spread chip sequence and by performing de-spreading and localizing processing to detect a localized pulse. According to the data transmission using the transmission and receiving method, data is mapped into a code sequence, and the receiving side can detect the data as the kind of code sequence, the shift time of a localized pulse and the polarity at a high SN ratio improvement rate.

A method includes: A transmit end obtains P QAM symbols; the transmit end performs IDWT or DWT on the P QAM symbols, to obtain a first signal matrix with N rows and M columns, and transposes the first signal matrix, to obtain a transposed first transpose matrix, where P, N, and M are all positive integers; and the transmit end outputs the transposed first transpose matrix. Correspondingly, a receive end obtains a second signal matrix with M rows and N columns; the receive end transposes the second signal matrix, to obtain a transposed second transpose matrix; and performs DWT or IDWT on the second transpose matrix, to obtain P QAM symbols.

The present invention provides a transmission method which generates and sends a transmission signal generated from a multiplexing OFDM signal or a multiplexing wavelet-OFDM signal employing a multiplexing-spread chip sequence in which a chip of a code sequence for spread and a code sequence for combination, and a chip of a code sequence for localization are multiplied and multiplexed, and a receiving method which makes a high SN ratio improvement rate possible by converting the received signal to a frequency domain to acquire the multiplexing-spread chip sequence and by performing de-spreading and localizing processing to detect a localized pulse. According to the data transmission using the transmission and receiving method, data is mapped into a code sequence, and the receiving side can detect the data as the kind of code sequence, the shift time of a localized pulse and the polarity at a high SN ratio improvement rate.