Abstract: A base station in a mobile communication system determines the number of slots that are to be used to transmit a synchronization signal in a period of the synchronization signal depending on the number of neighbor cells, allocates a synchronization signal region in which the synchronization signal is to be transmitted to a first slot of the determined number of slots depending on a cell identifier of a serving cell, and allocates a reserved region in which no signal is transmitted to slots other than the first slot among the determined number of slots so as to correspond to a position of the synchronization signal region.

Abstract: A method of searching a cell in a mobile station of a communication system in which a plurality of cells are grouped into a plurality of cell groups, each cell group including at least two cells, includes: detecting a primary synchronization signal and a secondary synchronization signal from a received signal; and identifying a cell based on a combination of the primary synchronization signal and the secondary synchronization signal. The secondary synchronization signal is related to the cell group to which the mobile station belongs and the primary synchronization signal is related to the cell to which the mobile station belongs within the cell group.

Abstract: A method and user equipment for transmitting a message of a random access procedure in a multi-beam system includes: transmitting and retransmitting a message 1 of the RA procedure through a first beam of a plurality of transmission beams of the UE based on power ramping; and retransmitting, if one or more Msg. 2 (RAR) is not successfully received corresponding to the message 1 transmission/retransmission, the message 1 through a second beam of the plurality of transmission beams after switching the first beam to the second beam at a second power level which is the same as or higher than a first power level of the first beam.

Abstract: Provided is a method for generating, by a base station, a common signal commonly required for surrounding terminals of the base station in a massive multiple input multiple output (MIMO) system. The base station generates data commonly required for the surrounding terminals. The base station generates a plurality of beamforming vectors using a time-domain constant amplitude (TCA)-frequency-domain constant amplitude (FCA) sequence having a constant size in a time domain and a frequency domain. Further, the base station generates a plurality of antenna streams corresponding to the common signal by multiplying the plurality of beamforming vectors by the data.

Abstract: Disclosed are a frame transmission method and a communication device performing the same. The communication device may transmit a null data packet (NDP)-announcement (NDP-A) including information on a plurality of communication devices participating in interference alignment and transmit an NDP including a common signal field and a common training field commonly applied to the plurality of communication devices.

Abstract: A method for transmitting and receiving a message for a random access (RA) between user equipment (UE) and a base station in a multi beam system includes: transmitting a synchronization signal (SS) block including a synchronization signal by performing beam sweeping for a multi beam; receiving a message 1 of an RA procedure from the UE; determining an optimal transmission beam to be used to transmit a message 2 of the RA procedure based on information about an association mapping between the SS block and a physical random access channel (PRACH) which is used to transmit the message 1; and transmitting the message 2 by using the optimal transmission beam.

Abstract: In a wireless communication system in which a plurality of base stations each forming a directional beam in one direction are disposed along a predetermined path, each base station estimates a distance from installed in a mobile body moving along the path if the TE enters a cell area of the corresponding base station; and controls the transmission power using a distance from the estimated TE so that a difference between received signal strength of the corresponding base station and the received signal strength of neighboring base stations measured by the TE in a cell boundary area between the base stations does not exceed a predetermined threshold value.

Abstract: A transmitting apparatus for modulating data based on a predetermined 2q-QAM constellation and a receiving apparatus and method for demodulating a signal based on the predetermined 2q-QAM constellation, wherein the last q-2 bits corresponding to a quadrant of the predetermined 2q-QAM constellation are same with a gray code of a 2q-2-QAM constellation, the last q-2 bits corresponding to the remaining quadrants of the predetermined 2q-QAM constellation are determined by performing symmetric transformation for the last q-2 bits of the quadrant of the predetermined 2q-QAM around the x-axis or the y-axis.

Abstract: There are provided an antenna apparatus and a method of handover using the antenna apparatus. The antenna apparatus may comprise a plurality of antenna elements forming a plurality of beams in a predetermined service area. The plurality of antenna elements are arranged in a plurality of rows, and a number of antenna elements included in an uppermost row of the plurality of rows is smaller than a number of antenna elements included in a downmost row of the plurality of rows, and differences between center angles of beams formed by the antenna elements included in the downmost row are larger than differences between center angles of beams formed by the antenna elements included in the uppermost row.

Abstract: A method and an apparatus for random access in a mobile communication system are provided. A terminal receives a synchronization signal block, obtains beam index information from the received synchronization signal block, and transmits a preamble message occupying a plurality of preamble resources including a preamble resource corresponding to the beam index information to a base station. A random access resource includes a plurality of preamble resources, and the synchronization signal block is specified for one beam and corresponds to one preamble resource of the random access resource.

Abstract: A method and an apparatus for transmitting a message used to access a base station (BS) in a random access (RA) procedure by user equipment (UE) are provided. The method includes: determining a first RA preamble resource corresponding to an SSB index which corresponds to a transmission beam among a plurality of transmission beams of BS; and transmitting a message 1 of the RA procedure by using a first RA preamble format which includes the first RA preamble resource and at least one second RA preamble resource which neighbors the first RA preamble resource.

Abstract: A method of searching a cell in a mobile station of a communication system in which a plurality of cells are grouped into a plurality of cell groups, each cell group including at least two cells, includes: detecting a primary synchronization signal and a secondary synchronization signal from a received signal; and identifying a cell based on a combination of the primary synchronization signal and the secondary synchronization signal. The secondary synchronization signal is related to the cell group to which the mobile station belongs and the primary synchronization signal is related to the cell to which the mobile station belongs within the cell group.

Abstract: A base station configures beam identifiers for a plurality of transmission beams. The base station configures virtual beam identifiers for the plurality of transmission beams based on the maximum number of transmission beams from the plurality of transmission beams that may spatially overlap one another, and the beam identifiers. The base station allocates resources using the virtual beam identifiers.

Abstract: Disclosed are a frame transmission method and a communication device performing the same. The communication device may transmit a null data packet (NDP)-announcement (NDP-A) including information on a plurality of communication devices participating in interference alignment and transmit an NDP including a common signal field and a common training field commonly applied to the plurality of communication devices.

Abstract: A signal transmitting method according to an exemplary embodiment of the present invention includes channel-coding broadcasting channel information by using a first scrambling code in a first frame within a broadcasting channel information updating period including a plurality of frames, and channel-coding the broadcasting channel information by using a second scrambling code in a second frame within the broadcasting channel information updating period. The second scrambling code is different from the first scrambling code.

Abstract: The present application relates to a method of generating a downlink frame. The method of generating the downlink frame includes: generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence and a second scrambling sequence determined by the primary synchronization signal; generating a third scrambling sequence determined by the first short sequence and a fourth scrambling sequence determined by the second short sequence; scrambling the short sequences with the respective scrambling sequences; and mapping the secondary synchronization signal that includes the first short sequence scrambled with the first scrambling sequence, the second short sequence scrambled with the second scrambling sequence and the third scrambling sequence, the second short sequence scrambled with the first scrambling sequence and the first short sequence scrambled by the second scrambling sequence and the fourth scrambling sequence to a frequency domain.

Abstract: A method and an apparatus for transmitting a signal by using a plurality of radio units (RUs) to a user equipment (UE). The apparatus is configured to: determine an RU set including at least two RUs of the plurality of the RUs based on a feedback regarding a received strength of a transmission beam formed by the plurality of the RUs, wherein the feedback is received from the UE; determine a distributed precoding matrix of which a diversity order is predetermined based on information about an RU included in the RU set; and perform a precoding based on the distributed precoding matrix and transmitting a precoded signal to the UE through the RU set.

Abstract: Provided is a data communication method performed at a transmission node, the method including collecting a node list including nodes communicable with the transmission node, exchanging the node list with each of the communicable nodes, determining an allowance of a space recycling transmission to a reception node by determining that the transmission node is a corresponding node as an exposed node in response to an occurrence of a clear-to-send (CTS) timeout, and transmitting data to the reception node based on a result of determining the allowance of the space recycling transmission.

Abstract: A method and a terrestrial base station for receiving an uplink signal. The terrestrial base station is configured to: receive a preamble corresponding to an orthogonal pseudo-noise (PN) sequence of a plurality of the orthogonal PN sequences from an onboard base station in a train; recognize identification (ID) of the onboard base station from the preamble, and allocate a temporary network ID and an uplink grant (UL grant) to the onboard base station; and receive the uplink signal transmitted based on the temporary network ID and the UL grant.

Abstract: A method of transmitting reference signals is provided by a transmitting apparatus in a wireless communication system. The transmitting apparatus transmits a first reference signal in a first time region of a resource block included in transmission duration. The transmitting apparatus transmits second reference signals scattered on two or more subcarriers in a second time region of the resource block. The second time region follows the first time domain and includes a plurality of symbols.