An optical transmitter transmits an orthogonal frequency division multiplexing symbol in which only one-half of available subcarriers are modulated with data and the remaining subcarriers are suppressed by not modulating with data. The transmission is of duration equal to half the symbol period of the OFDM symbol, resulting in a half-cycle transmission. An optical receiver receives the half-cycle transmission OFDM symbol, regenerates the full time domain representation and recovers data modulated on the one-half of available subcarriers. The modulated subcarriers and the suppressed subcarriers alternate in the frequency domain.

Methods and apparatuses are provided in which a signal is received at a receiver. A processor of the receiver computes frequency offset (FO) inter-carrier interference (ICI) compensation, based on a real matrix part of an approximate ICI matrix and an FO estimated from the received signal. The processor applies the FO ICI compensation to the received signal in a frequency domain to produce an ICI compensated output. The processor applies a phase rotation to the ICI compensated output.

A method for performing self-interference cancellation by a communication device which uses an FDR mode can comprise the steps of: measuring the strength of a residual self-interference signal, after antenna and analog self-interference cancellation, for each subband with respect to a predetermined number of subbands configured in a communication device; determining the order of a nonlinear self-interference signal component, to be considered for channel estimation of a nonlinear self-interference signal, for each subband on the basis of the strength of the residual self-interference signal that has been measured for each subband; and performing channel estimation of the nonlinear self-interference signal on the basis of the order that has been determined for each subband.

The method includes organizing a plurality of subscriber lines into a first group of subscriber lines and a second group of subscriber lines, the first group of subscriber lines at least including all the subscriber lines of the plurality of subscriber lines that do not support non-linear precoding operation and the second group of subscriber lines including the remaining subscriber lines of the plurality of subscriber lines; scaling first signals to be transmitted over respective ones of the first group of subscriber lines to confine respective intermediate transmit power levels at the input of a modulo unit and further to bypass or make ineffective the operation of the modulo unit; and processing the so scaled first signals and second signals to be transmitted over respective ones of the second group of subscriber lines through the first and second precoding stages.

A method of data transmission over guard sub-carriers is provided in a multi-carrier OFDM system. Adjacent radio frequency (RF) carriers are used to carry radio signals transmitted through adjacent frequency channels. A plurality of guard sub-carriers between adjacent frequency channels are aligned and identified for data transmission in a pre-defined physical resource unit. The identified guard sub-carriers do not overlap with normal data sub-carriers of the radio signals transmitted through the adjacent frequency channels. At least one of the identified guard sub-carriers is reserved as NULL sub-carrier. A flexible multi-carrier transceiver architecture is also provided in a multi-carrier OFDM system. Different multi-carrier and/or MIMO/SISO data transmission schemes are implemented by adaptively reconfigure same hardware modules including common MAC layer module, physical layer entities, and RF entities. Furthermore, the flexible multi-carrier transceiver architecture can be used to support data transmission over guard sub-carriers.

A method of estimating a channel for mobile systems with insufficient cyclic prefix length, wherein the channel comprises a plurality of multipath components (,), includes: receiving a signal (y.sub.n) comprising a plurality of contributions of a transmit signal (x.sub.n[k], x.sub.n-1[k]) transmitted during a plurality of transmission time intervals (n, n-1) on a plurality of sub-carriers of known pilots (kP.sub.b) and a plurality of sub-carriers of unknown data (k.Math.P.sub.b); determining an estimate of the plurality of multipath components (,) based on a probabilistic relation between the plurality of first contributions (x.sub.n[k], x.sub.n-1[k]) of the transmit signal, wherein the plurality of first contributions are transmitted during adjacent transmission time intervals (n, n-1), and an observation of the received signal (y.sub.n[k]) at a subcarrier (kP.sub.b) of the known pilots, wherein the probabilistic relation is based on statistical properties of the plurality of first contributions (x.sub.n[k], x.sub.n-1[k]) of the transmit signal.

Aspects of the disclosure relate to inter-link interference cancellation for reducing or mitigating interference from signals in different directions (e.g., uplink and downlink directions). A wireless communication device (i.e., a victim device subject to inter-link interference) may determine a time offset or lead time of an interfering signal from an offending device. Based on the determined time offset, the victim device may perform interference cancellation or suppression to reduce or mitigate the interference of the interfering signal. Other aspects, embodiments, and features are also claimed and described.

Methods, systems, and devices for wireless communications are described. For example, a wireless device may support physical broadcast channel (PBCH) precoding in high-doppler scenarios. In some cases, a base station may generate a synchronization signal block (SSB) including synchronization signals and PBCH signaling. The base station may transmit, to a UE, the PBCH signaling in accordance with an orthogonal time frequency space (OTFS) precoding and the synchronization signals in accordance with a non-OTFS precoding. The UE may monitor for the SSB and receive the PBCH signaling in accordance with the OTFS precoding and the synchronization signals in accordance with a non-OTFS precoding. The UE may establish or modify a connection with the base station according to the PBCH signaling.

An electronic device in a wireless communications system, the wireless communications system, and a method. The electronic device includes: a reception unit, configured to receive a signal from another electronic device in a wireless communications system; an analysis filtering unit, configured to set an analysis filter group according to a parameter of a non-perfect reconstruction filter group, decompose, by using the analysis filter group, signals received by the reception unit into multiple paths of sub-band signals and perform analysis filtering; and an interference cancellation unit, configured to, for each path of sub-band signals among multiple paths of sub-band signals, cancel inter-band interference in each path of sub-band signals according to each path of sub-band signals and neighboring sub-band signals thereof.

Systems and methods for canceling carrier frequency offset (CFO) and sampling frequency offset (SFO) in a radio receive chain are disclosed. In one embodiment, a method is disclosed, comprising: receiving a sub-frame via a radio receive chain in a time domain; performing per-user filtering on the sub-frame to obtain a signal for a particular user; obtaining a CFO correction signal; adding the CFO correction signal in the time domain to perform a CFO correction step on the signal for the particular user; performing an FFT on the output of the CFO correction step to obtain samples in a frequency domain; adding an SFO correction signal in the frequency domain to perform an SFO correction to the output of FFT step; and demodulating the output of SFO correction step, thereby performing CFO and SFO correction while reducing inter-carrier interference (ICI).