The invention provides a frequency offset estimation method for an OFDM-IM system. The method includes: S1. performing preliminary frequency offset compensation on a received signal subjected to non-uniform frequency offset by using a two-step method of: (1) resampling and down conversion; and (2) unified compensation for residual frequency offset , wherein in the step (2), a sum of energy of null sub-carriers is used as a cost function, an initial estimation value of is obtained by one-dimensional search, and the preliminary compensation is performed; S2. estimating positions of non-activated sub-carriers in the OFDM-IM system by using the signal subjected to the preliminary compensation; and S3. assigning certain weights to the estimated sub-carriers, adding energy of the estimated sub-carriers into the cost function according to different weights, obtaining a final estimation value of by the one-dimensional search performed on , and performing secondary compensation.

A method for operating a user equipment in a wireless communication is provided as an embodiment of the present invention. The method may include: receiving modulation and coding scheme (MCS) information for each of two or more codewords from a base station (BS); determining a demodulation reference signal (DMRS) antenna port to which a phase tracking reference signal (PTRS) antenna port is mapped based on the MCS information; and receiving a PTRS based on the DMRS antenna port, wherein a DMRS antenna port with the lowest index among one or more DMRS antenna ports included in a codeword with the highest MCS among the two or more codewords may be determined as the DMRS antenna port.

Disclosed are techniques related to wireless communication. In an aspect, a sequence generating entity factorizes a comb size N into prime factors of N, and generates one or more offset sequences for a reference signal for positioning based on one or more sequence lists associated with the prime factors of N and a number of symbols M over which the reference signal is scheduled.

Some examples of handling FTM requests comprises receiving a plurality of fine timing measurement (FTM) requests from a second network device over a first channel. Determining a channel traffic along the first channel. Adjusting a FTM response frequency based on the channel traffic. Responding based on the FTM response frequency, to a first number of FTM requests out of the plurality of FTM requests.

A method and apparatus provide synchronization signals and random access for flexible radio communication. Information can be received from a base station. The information can include a plurality of subcarrier spacings and at least one random access configuration for a cell. Each of the at least one random access configuration can be associated with at least one subcarrier spacing of the plurality of subcarrier spacings. The at least one subcarrier spacing can be used for communication. A random access configuration can be selected from the at least one random access configuration. A random access preamble can be transmitted according to the selected random access configuration.

Embodiments of the disclosure provide a method and apparatus for performing fractional subframe transmission. The method may comprise: determining first temporal information that indicates when a channel becomes available; and determining, based on the first temporal information and transmission opportunity information, second temporal information that indicates an end of the fractional subframe transmission.

Various embodiments relate to a method for processing received distributed multiple-input and multiple-output (DMIMO) OFDM signals from a plurality of transmitters, including: performing an initial carrier frequency offset (CFO) correction; receiving a plurality of OFDM symbols; re-constructing the channel every N symbols based upon a channel estimate for each transmitter and an estimate of residual CFO for each of the transmitters based upon the long term fields (LTF), wherein N is an integer; and equalizing the received OFDM symbols using the re-constructed channel.

A method and apparatus provide synchronization signals and random access for flexible radio communication. Information can be received from a base station. The information can include a plurality of subcarrier spacings and at least one random access configuration for a cell. Each of the at least one random access configuration can be associated with at least one subcarrier spacing of the plurality of subcarrier spacings. The at least one subcarrier spacing can be used for communication. A random access configuration can be selected from the at least one random access configuration. A random access preamble can be transmitted according to the selected random access configuration.

Aspects of the present disclosure provide techniques for design of synchronization signals for narrowband operation, which can be used for stand-alone/in-band/guard-band deployment. An example method is provided for operations which may be performed by a base station (BS). The example method generally includes generating a primary synchronization signal (PSS) utilizing a first code sequence and a cover code applied to the first code sequence over a first number of symbols within one or more subframes, generating a secondary synchronization signal (SSS) based on a second code sequence over a second number of symbols within one or more subframes, and transmitting the PSS and the SSS in the first and second subframes to a first type of a user equipment (UE) that communicates on one or more narrowband regions of wider system bandwidth.

Aspects of the present disclosure provide techniques for design of synchronization signals for narrowband operation and other clean-slate, OFDM based systems such as enhanced component carrier (eCC) systems. An example method is provided for operations which may be performed by a BS to generate and transmit a dual-layer PSS, and correspondingly, techniques for a UE to detect the dual-layer PSS. The PSS may be generated utilizing a binary code cover and at least one sequence applied to a number of symbols within one or more subframes of a frame.