Techniques are described for wireless communication. A first method includes receiving a first orthogonal frequency division multiplexing (OFDM) symbol including a plurality of reference signals (RSs) over a radio frequency spectrum band. The first method may also include receiving a second OFDM symbol including a first synchronization signal over the radio frequency spectrum band. A second method includes transmitting a first OFDM symbol including a plurality of RSs over an radio frequency spectrum band. The second method may also include transmitting a second OFDM symbol including a first synchronization signal over the radio frequency spectrum band. In each method, a first portion of the first OFDM symbol includes a higher density of the RSs than a remaining portion of the first OFDM symbol, and when included, the second OFDM symbol may be adjacent in time to the first OFDM symbol.

An apparatus includes an interference rejection combining module, at least partially implemented in hardware. The interference rejection combining module determines a covariance based on a Hermitian transpose of a signal received on a subcarrier of a symbol that is not a pilot symbol.

Embodiments of systems and methods for performing channel estimation on Orthogonal frequency-division multiplexing (OFDM) signals are described. In one embodiment, a method for performing channel estimation on an OFDM signal involves performing blind channel phase estimation on an OFDM signal to obtain channel phase information and performing blind channel magnitude estimation on the OFDM signal to obtain channel magnitude information. Each of performing blind channel phase estimation on the OFDM signal and performing blind channel magnitude estimation on the OFDM signal involves detecting and suppressing a signal path of the OFDM signal. Other embodiments are also described.

Techniques are described for wireless communication. A first method includes receiving a first orthogonal frequency division multiplexing (OFDM) symbol including a plurality of reference signals (RSs) over a radio frequency spectrum band. The first method may also include receiving a second OFDM symbol including a first synchronization signal over the radio frequency spectrum band. A second method includes transmitting a first OFDM symbol including a plurality of RSs over an radio frequency spectrum band. The second method may also include transmitting a second OFDM symbol including a first synchronization signal over the radio frequency spectrum band. In each method, a first portion of the first OFDM symbol includes a higher density of the RSs than a remaining portion of the first OFDM symbol, and when included, the second OFDM symbol may be adjacent in time to the first OFDM symbol.

There is provided a computer-implemented method of estimating transmitted signals in a communication system, the signals being transmitted by a transmitter to a receiver over a communication channel having a channel response, the method comprising estimating the transmitted signals based on generated trial sequences minimizing the channel response between adjacent received signals. There is also provided a receiver, a signal detector device and a communication system adapted to estimated transmitted signals in a communication system by generating trial sequences and determining the generated trial sequences minimizing the channel response between adjacent received signals. The present invention is particularly adapted for OFDM communication systems.

There is provided a computer-implemented method of estimating transmitted signals in a communication system, the signals being transmitted by a transmitter to a receiver over a communication channel having a channel response, the method comprising estimating the transmitted signals based on generated trial sequences minimizing the channel response between adjacent received signals. There is also provided a receiver, a signal detector device and a communication system adapted to estimated transmitted signals in a communication system by generating trial sequences and determining the generated trial sequences minimizing the channel response between adjacent received signals. The present invention is particularly adapted for OFDM communication systems.

Methods, apparatus and systems for reference signal configuration in a wireless communication are disclosed. In one embodiment, a method performed by a wireless communication device is disclosed. The method comprises: generating a pilot signal occupying N symbol resources, wherein the pilot signal includes at least one most sparse reference signal (RS) port that is determined from a predetermined pool of most sparse RS ports, wherein the predetermined pool includes at least N most sparse RS ports, wherein N is an integer larger than one; and transmitting a signal comprising the pilot signal to a wireless communication node.

There is provided a computer-implemented method of estimating transmitted signals in a communication system, the signals being transmitted by a transmitter to a receiver over a communication channel having a channel response, the method comprising estimating the transmitted signals based on generated trial sequences minimizing the channel response between adjacent received signals. There is also provided a receiver, a signal detector device and a communication system adapted to estimated transmitted signals in a communication system by generating trial sequences and determining the generated trial sequences minimizing the channel response between adjacent received signals. The present invention is particularly adapted for OFDM communication systems.

In some aspects of the systems, methods, and devices described herein, one or more asymmetric modulation constellations may be utilized. For example, a modulation constellation utilized to modulate data symbols may be asymmetric. In some approaches, an asymmetric modulation constellation may be generated by introducing a phase shift (e.g., cyclic shift, phase rotation) to one or more constellation points of a modulation constellation. An asymmetric modulation constellation may allow detecting phase shifts without ambiguity. For example, a user equipment (UE) may perform channel estimation or phase noise estimation aided by data symbols that are modulated with an asymmetric modulation constellation. In some examples, a UE may receive a message from a network entity indicating a configuration of an asymmetric modulation constellation. The UE may demodulate data symbols of a data signal based on a channel characterization estimate that is associated with the configuration of the asymmetric modulation constellation.

Systems, methods, apparatuses, and computer program products for generating sequences for zero-tail discrete fourier transform (DFT)-spread-orthogonal frequency division multiplexing (OFDM) (ZT DFT-s-OFDM) reference signals. One method includes adding a zero vector to an input sequence, and performing an iterative manipulation of the input sequence. The performing of the iterative manipulation of the input sequence may include, for example: computing frequency domain response of the sequence, normalizing elements of the computed frequency domain sequence to unitary power while maintaining phase of each of the elements, converting the sequence to time domain, generating a zero-padded sequence by forcing a zero head and tail of the sequence, and repeating the steps until a final sequence with zero-tail and flat frequency response is obtained.