A transmitter transmitting payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols, including: a frame builder configured to receive the payload data and to receive signalling data to use in detecting and recovering the payload data at a receiver, and to form the payload data with the signalling data into frames for transmission; a modulator configured to modulate a first OFDM symbol with the signalling data and to modulate one or more second OFDM symbols with the payload data; a signature sequence processor circuit providing a signature sequence; a combiner circuit combining the signature sequence with the first OFDM symbol; a prefixing circuit to prefixing a guard interval to the first OFDM symbol to form a preamble; and a transmission circuit transmitting the preamble and the one or more second OFDM symbols. The guard interval is formed from time domain samples of a part of the signature sequence.

A method and apparatus estimating carrier frequency offset (CFO) with timing synchronization are provided. The apparatus includes processor that receives analog-to-digital converter (ADC) samples, determines a coarse angle from the received ADC samples, obtains an improved coarse angle by altering the coarse angle based on a preamble duration, determines a base CFO estimate from the improved coarse angle and determines a plurality of candidate CFOs based on the base CFO estimate and a difference frequency.

A transmitter transmitting payload data using Orthogonal Frequency Division Multiplexed (OFDM) symbols, including: a frame builder configured to receive the payload data and to receive signalling data to use in detecting and recovering the payload data at a receiver, and to form the payload data with the signalling data into frames for transmission; a modulator configured to modulate a first OFDM symbol with the signalling data and to modulate one or more second OFDM symbols with the payload data; a signature sequence processor circuit providing a signature sequence; a combiner circuit combining the signature sequence with the first OFDM symbol; a prefixing circuit prefixing a guard interval to the first OFDM symbol to form a preamble; and a transmission circuit transmitting the preamble and the one or more second OFDM symbols. The guard interval is formed from time domain samples of a part of the signature sequence.

A data demodulation method, apparatus, and system are presented. The method includes obtaining notification information indicating that user equipment (UE) is in a high-speed moving state; performing time-frequency synchronization processing on first downlink data according to the notification information to obtain second downlink data; and performing demodulation processing on the second downlink data to obtain third downlink data, where in the demodulation processing, inter-transmission time intervals (TTIs) filtering for a channel estimation is not performed, or a filtering coefficient as a weight of a current TTI for a channel estimation is greater than a filtering coefficient as a weight of a TTI that is at the time when the UE is in the non-high-speed moving state for a channel estimation. The demodulation method is applicable to a high-speed scenario for improving a downlink data throughput of the UE.

A method and apparatus estimating carrier frequency offset (CFO) with timing synchronization are provided. The apparatus includes processor that receives analog-to-digital converter (ADC) samples, determines a coarse angle from the received ADC samples, obtains an improved coarse angle by altering the coarse angle based on a preamble duration, determines a base CFO estimate from the improved coarse angle and determines a plurality of candidate CFOs based on the base CFO estimate and a difference frequency.

A method for transmitting a synchronization signal in vehicle-to-something (V2X) communication is presented. A terminal according to the present invention can determine whether to transmit a synchronization signal on the basis of the power capacity of the terminal. The terminal can reduce power consumption by transmitting the synchronization signal only within a window according to the power capacity.

A data demodulation method, apparatus, and system are presented. The method includes obtaining notification information indicating that user equipment (UE) is in a high-speed moving state; performing time-frequency synchronization processing on first downlink data according to the notification information to obtain second downlink data; and performing demodulation processing on the second downlink data to obtain third downlink data, where in the demodulation processing, inter-transmission time intervals (TTIs) filtering for a channel estimation is not performed, or a filtering coefficient as a weight of a current TTI for a channel estimation is greater than a filtering coefficient as a weight of a TTI that is at the time when the UE is in the non-high-speed moving state for a channel estimation. The demodulation method is applicable to a high-speed scenario for improving a downlink data throughput of the UE.

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.

The Synthesizing Clock of OFDM Receiver (SCOR) is comprising methods and systems for synthesizing the OFDM receiver clock from a local clock in a feed-forward configuration, wherein the local clock is aligned in frequency to a received OFDM signal by using a frequency locked loop (FLL).

A data demodulation method, apparatus, and system are presented. The method includes obtaining notification information indicating that UE is in a high-speed moving state; performing time-frequency synchronization processing on first downlink data according to the notification information to obtain second downlink data; and performing demodulation processing on the second downlink data to obtain third downlink data, where in the demodulation processing, inter-TTIs filtering for a channel estimation is not performed, or a filtering coefficient as a weight of a current TTI for a channel estimation is greater than a filtering coefficient as a weight of a TTI that is at the time when the UE is in the non-high-speed moving state for a channel estimation. The demodulation method is applicable to a high-speed scenario for improving a downlink data throughput of the UE.