Systems and methods for a non-data-aided (NDA) approach to advanced OFDM timing are provided. This approach allows for accurate OFDM symbol timing and synchronization by avoiding inter-symbol interference (ISI) in multipath environments where an earliest arriving signal may not be the strongest signal. The NDA approach may rely on generating and applying a bias correction to a combined correlation result of the multi-path signals.

The present disclosure relates to the field of wireless communications technologies, relates to a signal sending device, a signal receiving device, a symbol timing synchronization method, and a system, and resolves a problem that complexity of symbol timing synchronization performed by a terminal with relatively low crystal oscillator accuracy is high. In a receiving device, a receiving module receives a synchronization signal including a first signal and a second signal. The first signal includes N1 generalized ZC sequences, and the second signal includes N2 generalized ZC sequences. The second signal is used to distinguish different cells or different cell groups. There are at least two generalized ZC sequences with different root indexes in (N1+N2) generalized ZC sequences. A processing module performs a first sliding correlation operation and a second sliding correlation operation on the synchronization signal, and performs symbol timing synchronization according to a relationship between a sliding correlation peak generated when a sliding correlation is performed on the N1 generalized ZC sequences and a sliding correlation peak generated when a sliding correlation is performed on the N2 generalized ZC sequences. This has relatively low implementation complexity, compared with an existing method in which grid search should be performed multiple times to compensate for a relatively large phase rotation.

Infrastructure equipment for transmitting data to and receiving data from a mobile device on a communications network is described. The infrastructure equipment comprising: transmitter circuitry configured to transmit the data to the mobile device; and controller circuitry configured to control the transmitter circuitry to transmit a first position reference signal in a first subframe and a second position reference signal in a second subframe, wherein the second position reference signal is a time adjusted version of the first position reference signal, the amount of time adjustment being determined by the sample time at which the mobile device samples the position reference signal.

Methods, systems, and devices for wireless communications are described. A first wireless device may identify a reference signal sequence (e.g., a demodulation reference signal (DMRS) sequence) based on a cyclic shift associated with a control channel for communications with a second wireless device. For example, the first wireless device may identify the cyclic shift associated with transmitting a message to the second wireless device via the control channel. In another example, the first wireless device may estimate the cyclic shift associated with receiving a message from the second wireless device via the control channel. The first wireless device may then communicate with the second wireless device based on the reference signal sequence. For example, the first wireless device may transmit or receive (e.g., via a shared channel) the reference signal sequence to or from the second wireless device.

Disclosed are techniques to compensate frequency systematic known error (FSKE) in reflector or initiator radios using a hybrid RF-digital approach in multi-carrier phase-based ranging. The hybrid RF-digital approach combines a coarse frequency compensation technique in the RF domain and a fine frequency compensation technique in the digital domain to remove the FSKE across all carrier frequencies from a device. The coarse frequency compensation performed in the RF domain may use a PLL to multiply the crystal frequency to arrive close to a target carrier frequency to compensate for a coarse portion of the known FSKE at the target frequency. The fine frequency compensation may use digital techniques to remove the remaining portion of the known FSKE not compensated by the RF. The hybrid approach reduces the number of fractional bits in the multiplier of the PLL when compared to an approach that uses only the RF-PLL to remove the FSKE.

Systems and methods for synchronize word correlation. The methods comprise: obtaining first values that each indicate a likelihood or probability that a respective timeslot in a symbol timing window of a carrier wave is meant or expected to include energy; multiplying, by the correlator, the first values respectively by correlation coefficients to produce a plurality of products (wherein at least one of the correlation coefficients comprises a negative coefficient value); generating a correlation value by combining the products together; determining whether a synchronization word has been detected with a given amount of likelihood based on the correlation value; and causing symbol timing synchronization at a receiver when a determination is made that the synchronization word has been detected with the given amount of likelihood based on the correlation value.

Disclosed are techniques for transmitting and receiving an extended narrowband positioning reference signal (NPRS) sequence. In an aspect, a base station generates the extended NPRS sequence and transmits, to at least one user equipment (UE) over a wireless narrowband channel, the extended NPRS sequence. In an aspect, a UE receives, over the wireless narrowband channel, an NPRS of a first subset of the extended NPRS sequence and measures the NPRS of the first subset of the extended PRS sequence. In an aspect, the extended NPRS sequence may be a function of a plurality of slot numbers of a plurality of slots of a plurality of sequential radio frames and a plurality of symbol indexes of a plurality of symbols of a single physical resource block.

Methods, apparatuses, and computer readable media for a common preamble for wireless local-area networks (WLANs). An apparatus of an access point (AP) or station (STA) comprising processing circuitry configured to decode a portion of a physical layer (PHY) protocol data unit (PPDU), the first portion of the PPDU including a physical universal signal field (U-SIG), the U-SIG comprising a version independent portion and a version dependent portion, the version independent portion including a version identifier field, the version identifier field indicating a standard version of the PPDU. The processing circuitry is further configured to refrain from decoding the version dependent portion when the standard version indicates a standard version of a later generation than a standard version of the AP or STA, and otherwise decode the version dependent portion in accordance with the standard version.

Systems, methods and computer software are disclosed for providing high resolution timing advance estimation based on Physical Random Access Channel (PRACH). An example method includes receiving a preamble signal r(n) having a predetermined sampling frequency and a predetermined length; correlating a down sampled version of the received preamble with a reference preamble sequence c(n) using an FFT method to provide correlation output Ryc; using a peak value P of the correlation output Ryc to detect a preamble ID and a timing advance at a resolution of 24 Ts; zero padding sequences Y(k) and C(k) so that they have a predetermined length resulting in sequences Y_hat(k) and C_hat(k), which are 1024-point FFT of y(n) and c(n); performing a maximum likelihood estimation (MLE) to estimate a timing offset; and detecting a peak value out of the R_hat(m) and using a corresponding index Q to provide a timing advance with an accuracy of 2 Ts.

Methods, systems and device for achieving synchronization in an orthogonal time frequency space (OTFS) signal receiver are described. An exemplary signal reception technique includes receiving an OTFS modulated wireless signal comprising pilot signal transmissions interspersed with data transmissions, calculating autocorrelation of the wireless signal using the wireless signal and a delayed version of the wireless signal that is delayed by a pre-determined delay, thereby generating an autocorrelation output, processing the autocorrelation filter through a moving average filter to produce a fine timing signal. Another exemplary signal reception technique includes receiving an OTFS modulated wireless signal comprising pilot signal transmissions interspersed with data transmissions, performing an initial automatic gain correction of the received OTFS wireless signal by peak detection and using clipping information, performing coarse automatic gain correction on results of a received and initial automatic gain control (AGC)-corrected signal.