BR-112020022381-B1 - TERMINAL FOR PERFORMING A CONTENT-BASED RANDOM ACCESS PROCEDURE FOR REQUESTING SYSTEM INFORMATION AND RELATED METHOD

BR112020022381B1BR 112020022381 B1BR112020022381 B1BR 112020022381B1BR-112020022381-B1

Abstract

TERMINAL AND METHOD OF COMMUNICATION BY A TERMINAL. A terminal includes a receiver configured to receive a Time Advance command; and a controller configured to control a timer related to uplink time alignment, wherein, in response to the receiver receiving the Time Advance command, the controller starts the timer, and wherein, upon the receiver receiving a contention resolution message, the controller stops the timer after a period of time from the receipt of the contention resolution message.

Inventors

Tooru Uchino
Hideaki Takahashi

Assignees

NTT DOCOMO, INC

Dates

Publication Date: 20260310
Application Date: 20180509

Claims (3)

1. Terminal (10) configured to perform a contention-based random access procedure for requesting system information, SI, characterized in that it comprises: a receiver (120) configured to receive, from a base station (20), a random access response, RAR, including a Time Advance command; and a controller (130) configured to control a timeAlignment timer, TA timer, for uplink time alignment, wherein, in response to receiving the Time Advance command in the RAR, the controller is configured to start the TA timer, and wherein, upon receiving, by the receiver, a contention resolution message, the controller is configured to stop the TA timer after transmitting acknowledgment information for the contention resolution message.
2. Terminal (10), according to claim 1, characterized in that the time period is maintained by a Medium Access Control (MAC) layer.
3. A communication method by a terminal (10) to perform a contention-based random access procedure for requesting system information, SI, the method characterized in that it comprises: receiving, from a base station (20), a random access response, RAR, including a Time Advance command; and controlling a timeAlignment timer, timer TA, for uplink time alignment, wherein, in response to receiving the Time Advance command in the RAR, the control starts the timer TA, and wherein, upon receiving a contention resolution message, the control stops the timer TA after transmitting acknowledgment information for the contention resolution message.

Description

TECHNICAL FIELD [001] The present invention relates to user equipment for a wireless communication system. TECHNICAL BACKGROUND [002] In 3GPP (3rd Generation Partnership Project), a wireless communication method called NR (New Radio) or 5G was studied in order to further increase system capacity, further increase data transmission speed, and further reduce latency in the wireless section (e.g., Non-Patent Document 1). For NR, several wireless technologies were studied in order to meet the requirements of achieving a transfer rate of 10 Gbps or more and reducing the latency of the wireless section to 1 ms or less. [003] In a cell, a propagation delay between the user equipment and a base station, which is the time elapsed for radio waves to propagate from the user equipment to the base station, is generally different for each unit of user equipment. Consequently, the timing of receiving the UL signal at the base station generally differs for each unit of user equipment that transmits the UL signal. The base station performs a Fast Fourier Transform (FFT) simultaneously for multiple UL signals from multiple units of user equipment. Consequently, in LTE, the timing of transmitting the UL signal is adjusted (time alignment) for each unit of user equipment so that the timing of receiving the multiple UL signals transmitted from multiple units of user equipment becomes the same at the base station. Operation that is the same as the operation described above is expected to be performed in NR. State of the Art Documents [Non-Patent Document] [004] Non-Patent Document 1: 3GPP TS 38.321 V15.1.0 (2018-03). [005] Non-Patent Document 2: 3GPP TSG-RAN WG2 Meeting #101bis, R2-1804691, Sanya, China, April 16 to April 20, 2018. SUMMARY OF THE INVENTION [PROBLEM TO BE SOLVED BY THE INVENTION] [006] In LTE, a network always transmits SI, regardless of whether the user equipment requiring System Information (SI) is present in the cell. For NR, it was studied to perform control to reduce a radio resource header by transmitting SI only when the user equipment requiring the SI is in the cell (Non-Patent Document 1). This system information is termed on-demand system information (on-demand SI). [007] When acquiring system information on demand, the user equipment transmits an IS request to a network, and in response, the network transmits the system information IS. As a method of transmitting an IS request, a method based on Message 1 of a random access procedure and a method based on Message 3 of a random access procedure have been specified. With respect to the method of acquiring system information based on Message 3 of the random access procedure, there is a need for a method by which the user equipment can properly perform a random access procedure. [WAYS TO SOLVE THE PROBLEM] [008] According to one aspect of the present invention, user equipment is provided including a transmitter that transmits a random access preamble to a base station; a receiver that receives a random access response transmitted from a base station; a controller that controls the user equipment; and a timer that operates on a time interval during which the timing to transmit an uplink signal from the user equipment is maintained, wherein, in response to the receiver receiving the random access response, the controller activates the timer and the controller causes the transmitter to transmit a message 3 including a message requesting the transmission of system information to the base station, and wherein the controller stops the timer after a period of time has elapsed from the receiver receiving a contention resolution message transmitted from the base station. [ADVANTAGES OF THE INVENTION] [009] According to the disclosed technique, a method is provided for acquiring system information based on Message 3 of a random access procedure with which the user equipment can perform a random access procedure appropriately. BRIEF DESCRIPTION OF THE DRAWINGS [010] FIG. 1 is a diagram illustrating a communication system configuration according to a modality. [011] FIG. 2 is a diagram illustrating an example of a random access procedure. [012] FIG. 3 is a diagram illustrating an example of propagation delay between user equipment and base station, which is the time elapsed for a radio wave to propagate from the user equipment to a base station in a cell. [013] FIG. 4 is a diagram illustrating an example of a method for transmitting an IS request based on a message 1 from a random access procedure. [014] FIG. 5 is a diagram illustrating an example of a method for transmitting an IS request based on a message 3 from a random access procedure. [015] FIG. 6 is a diagram illustrating an example in which the user equipment does not autonomously stop a TA timer when a random access procedure to perform an SI request based on Message 3 is completed. [016] FIG. 7 is a diagram illustrating an example in which the user equipment autonomously stops a TA timer when a random acces