Disclosed are a roll-off period detection method, a symbol starting point detection method, a fractional frequency offset estimating method, and an OFDM downstream system using the same. A method of detecting a roll-off period in an OFDM downstream system according to an embodiment of the present disclosure may include: generating a temporary roll-off period by applying a windowing function to a signal having a preset length; and detecting a roll-off period based on any one of a cross correlation and a sum of differences between a detection target signal included in a range of two OFDM symbol signals based on a detection starting point, and the temporary roll-off period.

A method of transmitting a signal by adaptively controlling windowing or filtering by a user equipment in a wireless communication system, includes the steps of receiving a message including a timing advance (TA) value from a base station, determining a windowing type or a filtering type corresponding to the TA value, and transmitting an uplink signal to which the determined windowing type is applied. In this case, the windowing type is distinguished according to a length of a valid symbol and the filtering type can be distinguished according to a filter coefficient value.

The present disclosure provides techniques for bandwidth constrained communication systems with frequency domain information processing. A bandwidth constrained equalized transport (BCET) communication system can include a transmitter, a communication channel, and a receiver. The transmitter can include a pulse-shaping filter that intentionally introduces memory into a signal in the form of inter-symbol interference, an error control code (ECC) encoder, a multidimensional fast Fourier transform (FFT) processing block that processes the signal in the frequency domain, and a first interleaver. The receiver can include an information-retrieving equalizer, a deinterleaver with an ECC decoder, and a second interleaver joined in an iterative ECC decoding loop.

System and methods for shaped single carrier orthogonal frequency division multiplexing with low peak to average power ratio are provided. The system receives an input signal and modulates the input signal to form Dirichlet kernels in a time domain to generate an offset Dirichlet kernel output time array where each Dirichlet kernel has a main lobe and a plurality of side lobes. Modulating the input signal suppresses a peak to average power ratio of the offset Dirichlet kernel output time array by reducing the plurality of side lobes of each Dirichlet kernel and respective amplitudes of the side lobes.

A method includes generating, by a transmitter, an original OFDM signal having at least one OFDM symbol, the at least one OFDM symbol having an associated time domain tail; truncating, by the transmitter, at least a portion of the time domain tail to produce a truncated OFDM signal; and transmitting, by the transmitter, the truncated OFDM signal.

Different filtered-orthogonal frequency division multiplexing (f-OFDM) frame formats may be used to achieve the spectrum flexibility. F-OFDM waveforms are generated by applying a pulse shaping digital filter to an orthogonal frequency division multiplexed (OFDM) signal. Different frame formats may be used to carry different traffic types as well as to adapt to characteristics of the channel, transmitter, receiver, or serving cell. The different frame formats may utilize different sub-carrier (SC) spacings and/or cyclic prefix (CP) lengths. In some embodiments, the different frame formats also utilize different symbol durations and/or transmission time interval (TTI) lengths.

Aspects of the description provide a method and devices to allow frequency domain spectral shaping (FDSS) to be used on both a reference sequence and data to enable low PAPR. Being able to use FDSS on both the reference sequence and data allows the FDSS to be transparent to the receiver. The method comprises obtaining a first sequence, wherein the first sequence is a base sequence of a set of base sequences, the set of base sequences comprising sub group base sequences, the first sequence obtained by cyclically repeating the sub group sequences at least once; and transmitting, by the device, a reference signal based on the first sequence.

A method of transmitting a signal by adaptively controlling windowing or filtering by a user equipment in a wireless communication system, includes the steps of receiving a message including a timing advance (TA) value from a base station, determining a windowing type or a filtering type corresponding to the TA value, and transmitting an uplink signal to which the determined windowing type is applied. In this case, the windowing type is distinguished according to a length of a valid symbol and the filtering type can be distinguished according to a filter coefficient value.

Embodiments of the present disclosure relate to systems and methods to generate a signal in a communication network. The method comprises fdtering a discrete Fourier transform spread orthogonal frequency division multiplexing (DFT-s-OFDM) data signal, and one of a DFT-S-OFDM and orthogonal frequency division multiplexing (OFDM) reference signal (RS) using a data filter and a RS filter respectively, to produce filtered data signal and filtered RS. The RS filter has one to one relationship with the data filter. Thereafter, port mapping the filtered RS to a corresponding port assigned to the transmitter to obtain port mapped filtered RS, wherein the port mapped filtered RS comprises a first subset of non-zero locations comprising of the filtered RS values and a second subset of zero locations comprising of zero values.

Techniques are disclosed for adaptively determining windowing functions and/or filtering functions in a system that uses multiple multicarrier modulation numerologies. According to one aspect, a method comprises determining (1610) first and second quantities of frequency resources needed for first and second multicarrier modulation schemes, respectively, the first and second multicarrier modulation schemes having first and second subcarrier spacings, respectively, the first subcarrier spacing differing from the second subcarrier spacing; determining (1620) a first windowing function and/or first filtering function, for use with the first multicarrier modulation scheme, based on at least one of the first and second quantities of frequency resources; and transmitting (1630) a multi-mode multi-carrier modulation signal in a frequency band, during the first interval, using the first and second multicarrier modulation schemes and the first and second quantities of frequency resources. Transmitting the multi-mode multi-carrier modulation signal comprises applying the first windowing and/or first filtering function to the first multicarrier modulation scheme.