A method and apparatus is provided, where a respective reference signal associated with each of one or more downlink transmit antenna ports in a wireless communication network is received. A value is determined for each of one or more measurable characteristics relative to each of the received reference signals. One or more parameters are received, the parameters including one or more adjustments, where each adjustment is specific to one of the downlink transmit antenna ports and include adjustments in the form of one or more respective offset values to be applied to at least some of the one or more determined values of the measurable characteristics of the received reference signals. At least one downlink transmit antenna port is then to function as a serving downlink transmit antenna port for the user equipment, based upon a comparison of the resulting values of the measurable characteristics of the received reference signals after the received one or more adjustments have been applied to the corresponding determined values.

A user equipment in a wireless communication system receives RACH configuration information including preamble format information indicating a first format and transmits a RACH preamble with the first format. The RACH preamble with the first format includes a cyclic prefix (CP) part and a sequence part in a time domain. The RACH preamble with the first format satisfies: a CP length of the RACH preamble of the first format is N times a CP length N.sub.CP of an orthogonal frequency division multiplexing (OFDM) symbol, where N is the number of OFDM symbols used to transmit a RACH preamble and is greater than 1.

Provided are a method and a device whereby a synchronization signal is transmitted and received. One embodiment of the present invention involves using one of a plurality of cells (first cell hereinbelow) in order to transmit synchronization signal setting information of a cell (second cell hereinbelow) set in an unlicensed band of the plurality of cells. The synchronization signal is transmitted on the second cell, based on the synchronization signal setting information. The synchronization signal is used in order to acquire time and frequency synchronization with the second cell.

A terminal device registration method and a device, where the method includes sending upstream registration window information to a terminal device, where the upstream registration window information indicates a starting position of an upstream registration window to the terminal device, receiving an upstream access signal sent by the terminal device from the starting position of the upstream registration window, where the upstream access signal includes a correlation sequence symbol and at least one orthogonal frequency division multiplexing (OFDM) symbol following the correlation sequence symbol, the correlation sequence symbol is constituted by a first sequence that meets a preset condition, and the at least one OFDM symbol modulates access information by means of differential phase modulation in a frequency domain, and performing upstream ranging according to the starting position of the upstream registration window and the correlation sequence symbol.

The present invention provides methods for relieving effective Doppler broadening in performing pin-point beamforming and provides apparatuses for supporting the methods, wherein the methods and the apparatuses are used in a wireless access system that supports a super high frequency band. The method for relieving Doppler broadening in a wireless access system that supports a super high frequency band according to one embodiment of the present invention may comprise the steps of: receiving a downlink signal at a receiving end; estimating a Doppler spectrum for the downlink signal received at the receiving end; and calculating a carrier wave shift value based on the Doppler spectrum estimated at the receiving end.

Disclosed are a method for transmitting a signal for device-to-device (D2D) communication of a user equipment in a wireless communication system and an apparatus for the same. Specifically, the method includes transmitting a D2D signal assigned at least one of a first synchronization information, a second synchronization information and a scheduling assignment information in a scheduling assignment resource unit. The first synchronization information and the second synchronization information are configured to be transmitted with different periodicities.

A preamble generating unit generates first and second synchronization preambles having different numbers of subcarriers. A transmission signal generating unit generates an OFDM transmission signal through time-division multiplexing by using the generated first and second synchronization preambles. A transmission RF unit converts the generated OFDM transmission signal into a radio-frequency OFDM signal and transmits the radio-frequency OFDM signal. The preamble generating unit adds a predetermined dummy period between the first synchronization preamble and the second synchronization preamble.

Various aspects provide for communicating a first set of broadcast reference signals (RSs) in a first subframe that includes a synchronization (SYNC) channel and communicating a second set of broadcast RSs in a second subframe that follows the first subframe. The second subframe may immediately follow the first subframe. A portion of the SYNC channel may include information indicating a configuration of broadcast RSs in one or more other subframes. The broadcast RSs may be configured for timing-error estimation, frequency-error estimation, and/or channel estimation. Additional and alternative aspects, embodiments, and features are also provided herein.

Wireless communications for a plurality of cell groups are described. Uplink transmissions, such as uplink transport blocks, hybrid automatic repeat request (HARQ) transmission, and/or channel state information transmission, may be based on one or more time alignment timers associated with a cell group.

The present invention relates to a method and an apparatus for implementing Listen-Before-Talk. According to an embodiment of the present invention, if the channel assessment does not stop at a boundary of the first symbol, the preamble comprises at least a first part, and if the channel assessment stops at the boundary of the first symbol, the preamble comprises a second part. And the first part is transmitted on a remaining portion of the first symbol until the end of the first symbol, and the second part is transmitted on at least one symbol following the first symbol. Besides, the data is transmitted to the receiving device in at least one symbol in the subframe in which the preamble transmission ends.