Abstract:
A base station infers a random access failure rate depending on a random access collision of terminals performing random access and controls a random access opportunity of a terminal that fails the random access by using the random access failure rate of each terminal. Also, information for the controlled random access opportunity is transmitted to the terminal that fails the random access.
Abstract:
A D2D (Device-to-Device) communication method is provided which enables a first terminal of a first group to directly communicate with other terminals of the first group without relay of a base station. The first terminal receives first data from a second terminal. The first terminal determines whether the first data is destined for the first group by using a group identifier of the first data. When the first data is destined for the first group, the first terminal identifies at least one first RLC entity, among multiple RLC (Radio Link Control) entities, that corresponds to the second terminal by using the source terminal identifier of the first data.
Abstract:
A method, a terminal, and a base station for performing random access by receiving additional random access information from the base station after connecting to the base station, selecting a random access preamble based on the additional random access information, and performing the random access by using the selected random access preamble is provided.
Abstract:
A first terminal receives a first Timing Advance (TA) value from a base station and includes a second TA value that is obtained based on the first TA value in a Scheduling Assignment (SA) signal. The first terminal transmits the SA signal to a second terminal at downlink (DL) timing for receiving a downlink signal of the base station in cellular communication. When a length of a Cyclic Prefix (CP) that is set for the D2D communication and a length of a CP that is set for the cellular communication are different, the first terminal transmits data of the D2D communication to the second terminal at first timing that is obtained by applying the second TA value to the DL timing.
Abstract:
A D2D (Device-to-Device) discovery method is provided which enables a first terminal within a first cell to discover a second terminal within a second cell without relay of a base station. The first terminal receives, from a first base station of the first cell, information about a first resource for D2D discovery through a SIB (System Information Block) or RRC (Radio Resource Control) message. The first terminal transmits a D2D discovery signal using the first resource.
Abstract:
Disclosed are a method and an apparatus for controlling distributed transmission power in device-to-device (D2D) communication. The D2D devices individually control their transmission power for the D2D communication link. In addition, a first terminal calculates the transmission power based on the measured channel gain and interference-plus-noise level. The first terminal determines optimal transmission power based on the calculated transmission power by the first terminal, and transmits a transmission power change message including the optimal transmission power to a second terminal. Next, the second terminal transmits a D2D signal based on the optimal transmission power.
Abstract:
A method for synchronization by a D2D terminal in a D2D communication network through receiving a first D2D synchronization signal from at least one D2D synchronization source and performing synchronization according to a synchronization timing reference provided through the first D2D synchronization signal, and a method for negotiating whether to perform a role as a synchronization source with another D2D synchronization source through determining, when a D2D synchronization signal and a D2D synchronization channel are received from at least one D2D synchronization source, whether to maintain a role as the independent synchronization source based on negotiation information for negotiation between synchronization sources included in the D2D synchronization channel, and operating as a relaying synchronization source when the role as the independent synchronization source is not maintained, are provided.