Provided are a method and apparatus for occupying an unlicensed carrier to send a discovery signal, and an access point. The method includes the following steps. A parameter of a discovery signal sent on an unlicensed carrier by an access point is configured. The access point sends the discovery signal on the unlicensed carrier. The technical solution of the present disclosure can reduce the time for processing items other than data sending (such as synchronization) after each time the access point preempts a resource, and can improve the spectral efficiency of the unlicensed carrier.

A method for performing uplink synchronization by a terminal in a millimeter wave (mmWave)-based wireless communication system according to an embodiment of the present invention comprises the steps of: repeatedly transmitting a first type random access preamble through a plurality of coarse beams that are sequentially formed for different directions; performing a first timing advance (TA) adjustment on the basis of a response of a base station with respect to a repeated transmission of the first type random access preamble; and transmitting a second type random access preamble through at least one fine beam having a smaller beam width than the coarse beams, wherein the sequence of the second type random access preamble transmitted after the first TA adjustment is configured to be shorter than the sequence of the first type random access preamble on the time axis.

A method and apparatus provides a determination of a set of sequence values to be used as synchronization signal sequences, the set of sequence values having a predetermined length. Each sequence value in the set is based upon a first maximum length sequence having a first cyclic shift, and is based upon a second maximum length sequence having a second cyclic shift. For at least one group of possible sequence values from the determined set, where a value of a cyclic shift difference between the second cyclic shift of the second maximum length sequence and the first cyclic shift of the first maximum length sequence upon which each of the possible sequence values in the group are based are equal, a cyclic shift difference between the respective first cyclic shift value of the first maximum length upon which each of the possible sequence values in the group are based for any two of the possible sequence values in the group are larger than or equal to a threshold value, where the threshold value is determined based on an expected maximum carrier frequency offset value. The method further includes assigning each one of the determined set of sequence values to respective at least one communication target of a plurality of communication targets.

Certain aspects of the present disclosure relate to methods and apparatus for generating synchronization signals for cell synchronization. Certain aspects of the present disclosure provide a method for wireless communication. The method generally includes determining a symbol index for transmitting a sequence; determining an amount of cyclical shift in one of a frequency domain and a time domain to apply to the sequence, wherein the amount of cyclical shift in the frequency domain is based on the sequence and the symbol index; shifting the sequence by the amount of cyclical shift; and transmitting the shifted sequence in a symbol corresponding to the symbol index.

There is disclosed a method of operating a transmitting radio node in a wireless communication network, the method including transmitting reference signaling based on a reference pilot sequence, the reference pilot sequence being one of a set of reference pilot sequences, at least one reference pilot sequence of the set being a subsequence of another reference pilot sequence of the set. The disclosure also pertains to related devices and methods.

Methods, systems, and devices for wireless communication are described. A base station may transmit a subframe that includes physical broadcast channel (PBCH) signals interspersed within beam reference signals, where the subframe may be a synchronization subframe including one or more synchronization signals. In some cases, the beam reference signals from different antenna ports may be code division multiplexed or frequency division multiplexed over multiple frequency tones. A user equipment (UE) may use the beam reference signals to generate channel estimates for the PBCH signals. In some cases, orthogonal cover codes for code division multiplexed signals may be selected to facilitate generation of channel estimates for PBCH signals transmitted using nearby frequency tones.

Provided is a synchronization method and apparatus in a wireless communication system. A synchronization method according to an aspect of the present disclosure may include: receiving a first synchronization signal and a second synchronization signal; determining a priority order of the first synchronization signal and the second synchronization signal; and performing synchronization based on a synchronization signal having a higher priority between the first synchronization signal and the second synchronization signal.

The present specification provides a method for obtaining downlink synchronization in a machine type communication (MTC) apparatus. The MTC apparatus may comprise the steps of: receiving an MTC-dedicated synchronization signal from a base station on the subframe before a subframe which attempts to receive a paging message; obtaining a downlink synchronization of the base station through the synchronization signal; and after obtaining the downlink synchronization, attempting to receive the paging message. Here, the MTC-dedicated synchronization signal may be received on the same sub-band as a sub-band on which the paging message is received, from among the entire system band of the base station.

A communication apparatus includes a receiver and a decoder. The receiver includes a plurality of antenna elements and, in operation, receives from a base station apparatus a modulated signal mapped to one of a plurality of subframes defined in a frame corresponding to a communicable range to which the communication apparatus belongs. The plurality of subframes are defined by time-division, frequency-division, or time-and-frequency division of the frame. A maximum number of modulated signals that can be simultaneously transmitted in a subframe from the base station apparatus varies depending on the communicable range. The decoder, in operation, decodes the received modulated signal.

A symbol boundary in a data packet having a guard interval preceding a preamble having a predetermined sequence of symbols is detected by receiving a signal representing a data packet; sampling the received signal at a sampling rate; estimating channel impulse responses from a set of samples in dependence on the predetermined sequence of symbols of the preamble; determining an energy value for each of a plurality of windows of channel impulse responses, each of the windows corresponding to W number of consecutive samples, the energy value for each of the windows being indicative of the total energy associated with the channel impulse responses of that window; determining which of the windows has the greatest energy value; and identifying the earliest sample of the consecutive W samples in said determined greatest energy window, the earliest sample being indicative of a symbol boundary for the preamble.