Patent Description:
In the 3GPP (3rd Generation Partnership Project), a wireless communication method called NR (New Radio) or <NUM> has been studied in order to further increase the capacity of the system, further increase the data transmission speed, and further reduce the latency in the wireless section (e.g., Non-Patent Document <NUM>). For NR, various wireless technologies have been studied in order to meet the requirements of achieving throughput of <NUM> Gbps or more and reducing the latency of the wireless section to <NUM> or less.

In a cell, a propagation delay between user equipment and a base station, which is elapsed time for radio waves to propagate from the user equipment to the base station, is generally different for each unit of user equipment. Accordingly, 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) at a same time for multiple UL signals from multiple units of user equipment. Accordingly, in the LTE, the timing of transmission of the UL signal is adjusted (time alignment) for each unit of user equipment so that the timing of reception of the multiple UL signals transmitted from multiple units of user equipment becomes the same at the base station. It is expected that the operation that is the same as the above-described operation is performed in NR.

In the 3GPP standard contribution entitled "<NPL>), the authors disclose how to handle TA timer for Msg3 based SI request procedure.

In the 3GPP standard contribution entitled "<NPL>), the authors disclose the potential MAC impacts on the msg3-based SI request.

<CIT> discloses a communication scheme and system for converging a 5th generation (<NUM>) communication system for supporting a data rate higher than that of a 4th generation (<NUM>) system with an internet of things (loT) technology. The disclosure is applicable to intelligent services (e.g., smart home, smart building, smart city, smart car, connected car, health care, digital education, retail, and security and safety-related services) based on <NUM> communication technology and IoT-related technology. The disclosure relates to a technology about system information request-related operations of a terminal and a base station.

In the 3GPP standard contribution entitled "<NPL>), the authors disclose determination of PUCCH duration and a PUCH resource for HARQ-ACK feedback in response to Msg4.

In LTE, a network always transmits SI regardless of whether user equipment requiring System Information (SI) is present in the cell. For NR, it has been studied to perform controlling to reduce an overhead of radio resources by transmitting SI only when the user equipment requiring the SI is in the cell (Non-Patent Document <NUM>). Such system information is called on demand system information (on demand SI).

When acquiring system information on demand, user equipment transmits a SI request to a network and, in response to that, the network transmits the system information SI. As a method for transmitting an SI request, a method based on Message <NUM> of a random access procedure and a method based on Message <NUM> of a random access procedure have been specified. With regard to the method of acquiring system information based on Message <NUM> of the random access procedure, there is a need for a method with which user equipment can perform a random access procedure appropriately.

According to an aspect of the present invention, there are provided a terminal according to claim <NUM> and a communication method according to claim <NUM>.

According to the disclosed technique, a method is provided which is for acquiring system information based on Message <NUM> of a random access procedure with which user equipment can perform a random access procedure appropriately.

The embodiments of <FIG> and <FIG> fall under the scope of the appended claims. The other embodiments do not fall under the scope of the claims and are to be regarded as mere examples useful to better understand the invention.

In the following, embodiments of the present invention (the embodiments) are described with reference to the drawings. Note that the embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the following embodiments.

Although the wireless communication system in the following embodiments is assumed to be basically conformed to NR, this is an example, and the radio communication system in the embodiments may conform, in part or in whole, to a wireless communication system other than NR (e.g., LTE).

<FIG> is a configuration diagram of a radio communication system according to an embodiment. The radio communication system according to the embodiment includes user equipment <NUM> and a base station <NUM>, as shown in <FIG>. In <FIG>, one unit of user equipment <NUM> and one base station <NUM> are shown. However, this is an example and there may be a plurality of units of user equipment <NUM> and a plurality of base stations <NUM>.

The user equipment <NUM> is a communication device provided with a radio communication function, such as a smartphone, a cellular phone, a tablet, a wearable terminal, a communication module for Machine-to-Machine (M2M), etc., which wirelessly connects to base station <NUM> and utilizes various communication services provided by the radio communication system. The base station <NUM> is a communication device that provides one or more cells and wirelessly communicates with user equipment <NUM>.

In the embodiments, a duplex method may be a TDD (Time Division Duplex) method or an FDD (Frequency Division Duplex) method.

First, a basic process of a contention-based random access procedure in an LTE is described by referring to <FIG>. It is assumed that a procedure similar to this procedure is performed in NR.

The user equipment transmits, on a PRACH (Physical Random Access Channel), a RA preamble (selected sequence, Message <NUM>) using one sequence among a predetermined number of RA preambles (sequences) (step <NUM>). No contention occurs, provided that there is no other UE that performs random access using the same sequence at the same time.

At step S2, the base station uses the DL-SCH (Downstream Shared Channel) to transmit Random Access Response (RAR) to the user equipment including a TA (timing advance) command for adjusting transmission timing of the user equipment, a detected RA preamble index, uplink resource allocation information (UL grant), etc..

The user equipment that receives the RAR adjusts uplink timing and transmits a control message (Message <NUM>), such as an RRC connection request, to the base station using the allocated resources (step S3).

If the user equipment that transmits the RA sample fails to receive an RA response (when a random access attempt fails), the user equipment increases the transmit power by a predetermined step size and transmits the PRACH each time a failure occurs. Such an operation is called Power Ramping.

At step S4, the base station transmits a contention resolution message (a contention resolution message). The user equipment that receives the content solution message completes the random access procedure by verifying that the content solution message includes the user equipment's ID (e.g., the Common Control Channel Service Data Unit (CCCH SDU) or the TC-RNTI, which was used for scrambling in step S3), and, subsequently, the user equipment performs transmission and reception of the data.

As described above, at step S2 of the random access procedure, the base station transmits a RAR including the TA command to the user equipment. The reasons are as follows.

As illustrated in <FIG>, a propagation delay between user equipment and a base station, which is time elapses for radio waves to propagate from user equipment to a base station in a cell, generally differs for units of user equipment. Accordingly, timing for receiving a UL signal at the base station generally generally differs for each unit of user equipment that transmits the UL signal. The base station performs a Fast Fourier Transform (FFT) at a same time for multiple UL signals from multiple units of user equipment. Accordingly, in the LTE, transmission timing of a UL signal is adjusted (time alignment) for each unit of user equipment, so that reception timing of multiple UL signals transmitted from multiple units of user equipment is the same at the base station. Time alignment is performed by a TA command transmitted from the base station to the user equipment. That is, the user equipment adjusts the transmission timing of the UL signal based on the TA command received from the base station. Such time alignment is assumed to be followed by NR.

System information (System Information, SI) is divided into a MasterInformation Block (MIB) and several System Information Blocks (SIB). A MasterInformation Block (MIB) is always transmitted on a Broadcast Channel (BCH) with a periodicity of <NUM>, and the Master Information Block includes a parameter required to get SystemInformationBlockType <NUM> (SIB1) from the cell.

A SystemInformationBlockType1 (SIB1) includes information about the availability and scheduling of multiple other SIBs (e.g., periodicity, SI window size). The SIB1 also indicates whether the multiple other SIBs are transmitted based on periodic broadcasts or only on-demand.

A SIB other than SIB1 is transmitted in a SystemInformation (SI) message transmitted on a DL-SCH. Each SI message is transmitted in multiple windows (called SI windows) in a time-domain, which are periodically generated.

A MIB includes basic information, such as a system bandwidth, a system frame number (SFN: System Frame Number), and a number of transmitting antennas.

In LTE, a network always transmits SI, regardless of whether user equipment requiring SI exists in a cell. For NR, it has been studied to perform control for reducing overhead of radio resources by transmitting SI only if there exists user equipment requiring the SI in a cell (Non-Patent Document <NUM>). Such system information is called on demand system information (on demand SI).

For acquiring system information on demand, user equipment <NUM> transmits an SI request to a network and the network transmits the system information SI in response thereto.

As a method for transmitting an SI request, a method based on Message <NUM> of a random access procedure and a method based on Message <NUM> of a random access procedure are specified.

A method of transmitting an SI request based on Message <NUM> of a random access procedure is described below. The base station <NUM> (also called gNB, gNodeB, <NUM> base station, NR base station, etc.) allocates individual RA preambles for respective SIs in advance, and the user equipment <NUM> acquires necessary SI by transmitting an SI request using a corresponding RA preamble. A specific procedure is described by referring to <FIG>.

<FIG> is a diagram illustrating an example of a method of transmitting an SI request based on Message <NUM> of a random access procedure. First, at step S101, an event (SI request trigger) that requires transmission of an SI request occurs in the user equipment <NUM>.

In response to occurrence of the SI request trigger at step S101, the user equipment <NUM> selects an RA preamble corresponding to the SI at step S103 and the user equipment <NUM> transmits the selected RA preamble to the base station <NUM>.

In response to receiving the RA preamble corresponding to the SI, the base station <NUM> returns an RA preamble ID corresponding to the received RA preamble to the user equipment <NUM> at step S105.

Subsequently, the base station <NUM> starts transmitting the SI (step S107).

Next, the method of transmitting the SI request based on Message <NUM> of the random access procedure is described. This method can be applied to a case in which no RA preamble for an SI request is configured, and the method is such that an RRC message for an SI request is transmitted by Message <NUM> of a random access procedure while activating the random access procedure. A specific procedure is described by referring to <FIG>.

<FIG> is a diagram illustrating an example of a method of transmitting a SI request based on Message <NUM> of a random access procedure. First, at step S201, an event (SI request trigger) that requires transmission of an SI request occurs in the user equipment <NUM>.

In response to occurrence of the SI request trigger at step S201, the user equipment <NUM> transmits an RA preamble at step S203.

In response to receiving the RA preamble from the user equipment <NUM>, the base station <NUM> transmits a Random Access Response (RAR) to the user equipment <NUM> at step S205.

In response to receiving the RAR from the base station <NUM>, the user equipment <NUM> transmits Message <NUM> including an SI request to the base station <NUM> at step S207.

In response to receiving Message <NUM> from the user equipment <NUM>, the base station <NUM> transmits a contention resolution message (contention resolution message) to the user equipment <NUM> at step S209.

Subsequently, the base station <NUM> starts transmitting the SI (step S211). In the following, details of the method of transmitting the SI request based on the above-described Message <NUM> are described.

In each of the user equipment <NUM> and the base station <NUM>, for example, a Radio Resource Control (RRC) layer sets a TA timer (timeAlignment Timer) to maintain uplink time adjustment. The TA timer is used to control a length of time during which a Medium Access Control (MAC) entity maintains the Time Alignment of an uplink.

Here, a timer is running once it is started, until it is stopped or until it expires; otherwise it is not running. If a timer is not running, the timer can be started. If a timer is running, the timer can be restarted. A timer is always started or restarted from an initial value of the timer (Non-Patent Document <NUM>). In each of the user equipment <NUM> and the base station apparatus <NUM>, a timer may be implemented in a known method, such as, for example, a processor counting up a counter from an initial value or counting down from an initial value. However, a method of implementing a timer is not specified in this specification.

Usually, when a TA timer of the user equipment <NUM> is not running and the user equipment <NUM> receives a TA command in a random access procedure, the user equipment <NUM> starts or restarts the TA timer. Subsequently, the user equipment <NUM> does not autonomously stop the TA timer. Namely, the TA timer of the user equipment <NUM> stops by expiry.

In this regard, as an agreement in the 3GPP standardization, upon completion of a random access procedure for a Messages based SI request, the user equipment <NUM> can autonomously stop the TA timer (Non-Patent Document <NUM>).

Referring to <FIG> and <FIG>, a case in which the user equipment <NUM> does not autonomously stop the TA timer and a case in which the user equipment <NUM> autonomously stops the TA timer are described, respectively.

<FIG> illustrates an example in which the user equipment <NUM> does not autonomously stop the TA timer. As shown in <FIG>, at step S301, the user equipment <NUM> starts a random access procedure for the Messages based SI request. The user equipment <NUM> transmits a random access preamble to the base station <NUM> in step S303. In response to receiving a random access preamble, the base station <NUM> transmits a random access response (Random Access Response, RAR) to the user equipment <NUM> at step S305. At this time, the user equipment <NUM> starts the TA timer in response to receiving the TA command included in the random access response.

Subsequently, in response to receiving a random access response at step S305, the user equipment <NUM> transmits Message <NUM> including an SI request to the base station <NUM> at step S307.

In response to receiving a message <NUM> including SI request in step S307, the base station <NUM> transmits a content solution message (contention resolution message) to the user equipment <NUM> at step S309. Subsequently, at step S311, the base station <NUM> starts transmitting system information.

Next, at step S313, the user equipment <NUM> starts another RRC procedure. As a reason for starting another RRC procedure, for example, the following cases can be considered: a case in which synchronization with the base station <NUM> is to be established again; a case in which an RRC connection with the base station is to be resumed, etc..

At step S315, the user equipment <NUM> transmits a random access preamble to the base station <NUM>. In response to receiving a random access preamble at step S315, the base station <NUM> transmits the RAR to the user equipment <NUM> at step S317. In this case, the user equipment <NUM> has already started the TA timer at step S305 and the TA timer is running. As described in Non-Patent Document <NUM>, the 3GPP standard specifies that when a TA command is received while a TA timer is running in a contention-based random access procedure, the MAC entity of the user equipment <NUM> ignores the TA command. Accordingly, the user equipment <NUM> ignores the TA command received at step S317. Namely, even if the TA command is received at step S317, the user equipment <NUM> does not start or restart the TA timer, and the TA timer continues running. In this case, in response to receiving the RAR at step S317, the user equipment <NUM> attempts to transmit Message <NUM>. However, prior to sending message <NUM>, a TA timer may expire. Alternatively, even if the expiration of the TA timer is after transmission of Message <NUM> by the user equipment <NUM> at step S319, at the base station <NUM> activates the TA timer at a timing at which the RAR is transmitted at step S317, so that the TA timer of the user equipment <NUM> may expire prior to expiration of the TA timer of the base station <NUM>. Namely, the activation state of the TA timer of the user equipment <NUM> and the activation state of the TA timer of the base station <NUM> may not match.

In order to avoid inconsistencies in the activation states of the above-described TA timers, in the standardization of 3GPP, an agreement has been reached such that, when the RA procedure for Message <NUM> based SI request is completed, user equipment autonomously stops a TA timer (Non-Patent <NUM>).

<FIG> illustrates an example in which the user equipment <NUM> autonomously stops the TA timer when the RA procedure for the Message <NUM>-based SI request is completed.

As shown in <FIG>, at step S401, the user equipment <NUM> starts a random access procedure for a Message3 based SI request. The user equipment <NUM> transmits a random access preamble to the base station <NUM> at step S403. In response to receiving a random access preamble, the base station <NUM> transmits a random access response (Random Access Response, RAR) to the user equipment <NUM> at step S405. At this time, the user equipment <NUM> starts the TA timer in response to receiving the TA command included in the random access response.

In response to receiving a random access response at step S405, the user equipment <NUM> transmits Message3 including SI request to the base station <NUM> at step S407.

In response to receiving Message <NUM> including SI request at step S407, the base station <NUM> transmits a content solution message (contention resolution message) to the user equipment <NUM> at step S409. Here, the user equipment <NUM> stops the TA timer in response to receiving the content solution message at step S409. Subsequently, at step S411, the base station <NUM> starts transmitting system information.

Next, at step S413, the user equipment <NUM> starts another RRC procedure. As a reason for starting another RRC procedure, for example, cases can be considered, such as a case in which resynchronization with a base station is to be established and a case in which an RRC connection with a base station is to be resumed.

At step S415, the user equipment <NUM> transmits a random access preamble to the base station <NUM>. In response to receiving a random access preamble at step S415, the base station <NUM> transmits an RAR to the user equipment <NUM> and starts the TA timer of the base station <NUM> at step S417. The user equipment <NUM> starts the TA timer of the user equipment <NUM> in response to receiving a TA command included in the random access response received at step S417. Subsequently, at step S419, the user equipment <NUM> transmits Message <NUM> including an SI request to the base station <NUM>.

As described above, since the base station <NUM> starts the TA timer of the base station <NUM> at step S417 and the user equipment <NUM> that receives the TA command at step S417 starts the TA timer of the user equipment <NUM>, inconsistency between the running state of the TA timer of the user equipment <NUM> and the running state of the TA timer of the base station <NUM> can be avoided, such as a case in which the TA timer of the user equipment <NUM> expires prior to expiration of the TA timer of the base station <NUM>.

However, there is a problem described below with the method in which the user equipment <NUM> autonomously stops the TA timer upon completion of the above-described RA procedure for the Message <NUM> based SI request.

While the TA timer is stopped, uplink transmission timing of the user equipment <NUM> is not established. For this reason, according to the 3GPP standard, the user equipment <NUM> is disallowed to transmit an uplink signal except for transmitting a random access preamble on a Physical Random Access Channel (PRACH) (Non-Patent Document <NUM>). Accordingly, as described above, upon completion of the contention resolution, i.e., upon receipt of the contention resolution message at step S409 of <FIG>, if the TA timer of the user equipment <NUM> is immediately stopped, the user equipment <NUM> is unable to transmit the acknowledgment information (Acknowledgement, ACK, or NAK) for the contention resolution message. As a result, the base station <NUM> is unable to detect that the user equipment <NUM> has received the content solution message. In this regard, for example, the base station <NUM> can increase a probability of receiving, by the user equipment <NUM>, a contention resolution message by a method of blindly transmitting a contention resolution message multiple times. However, in this case, radio resources are wasted.

<FIG> and <FIG> are diagrams illustrating the above-described problem. As shown in <FIG>, according to a competition-based random access (Content Based Random Access, CBRA) procedure other than a random access procedure for an SI request, the user equipment <NUM> is able to transmit the acknowledgement information of Message4 to the base station <NUM> because the TA timer is not stopped prior to transmitting the acknowledgement information of Message4 (content resolution message).

In contrast, for a CBRA for an SI request illustrated in <FIG>, when Message4 is received, the user equipment <NUM> stops the TA timer of the user equipment, so that the user equipment <NUM> is unable to transmit the acknowledgement information of Message4, and the base station <NUM> is unable to confirm whether Message <NUM> has been received by the user equipment <NUM>.

As a method for solving the above-described problem, a method can be considered such that, in a CBRA for an SI request, the TA timer is kept running until completion of transmission of the acknowledgement information by the UE. Namely, the user equipment <NUM> stops the TA timer of the user equipment <NUM> after the user equipment <NUM> completes the transmission of the acknowledgement information to the message <NUM> (content solution message). In the following, details of this method are described by referring to <FIG>.

<FIG> is a diagram illustrating an example of a method in which user equipment stops the TA timer after completing transmission of the acknowledgement information. At step S601, the user equipment <NUM> starts a CBRA for an SI request. At time T1, the user equipment <NUM> transmits Message1 (RA preamble) to the base station <NUM> (at step S603). In response to receiving message <NUM>, the base station <NUM> transmits Message2 (RAR) to the user equipment <NUM> at time T2 (step S605). In response to receiving message <NUM>, the user equipment <NUM> transmits Messages (SI request) to the base station <NUM> at time T3 (step S607). In response to receiving Messages, the base station <NUM> transmits Message4 (content solution message) to the user equipment <NUM> at time T4 (step S609). In response to receiving Message <NUM>, the user equipment <NUM> completes transmission of the acknowledgement information for Message4 to the base station <NUM> at time T5 (Step S611). Subsequently, the user equipment <NUM> stops the TA timer at time T6 after time T5, which is the time at which transmission of the acknowledgement information to the base station <NUM> is completed.

That is, the method is such that the user equipment <NUM> delays the stop of the TA timer of the user equipment <NUM> upon completion of the CBRA for the SI request.

Here, the user equipment <NUM> may stop the TA timer of the user equipment <NUM> at a timing at which the acknowledgement information is transmitted. Alternatively, the user equipment <NUM> may stop the TA timer of the user equipment <NUM> in a radio frame immediately after the radio frame at the timing at which the acknowledgement information is transmitted. Alternatively, the user equipment <NUM> may stop the TA timer of the user equipment at a sub-frame immediately after the sub-frame at a timing at which the acknowledgement information is transmitted. Alternatively, the user equipment <NUM> may stop the TA timer of the user equipment at a slot immediately after the slot at which the acknowledgement information is transmitted. Alternatively, the user equipment <NUM> may stop the TA timer of the user equipment at a symbol immediately after the symbol at a timing at which the acknowledgement information is transmitted.

In addition, the user equipment <NUM> may stop the TA timer after a time period after a successful contention resolution, i.e., a successful CBRA. Here, a time period may be managed at any layer of the user equipment <NUM>, such as the Medium Access Control (MAC) layer of the user equipment <NUM> or the Radio Resource Control (RRC) layer of the user equipment <NUM>. Alternatively and/or additionally, a time period may be managed at any layer of base station apparatus <NUM>, such as a Medium Access Control (MAC) layer of base station apparatus <NUM> or a Radio Resource Control (RRC) layer of base station apparatus <NUM>.

When a time period is managed by the MAC layer, the MAC layer may autonomously stop the TA timer of the user equipment <NUM> upon expiration of the TA timer. Alternatively, the MAC layer may inform the upper layer (e.g., the RRC layer) that a time period has elapsed (expiration of the TA timer), and the MAC layer may then be indicated from the upper layer to stop the TA timer of the user equipment <NUM>. For example, the MAC layer may stop the TA timer of the user equipment <NUM> by receiving a MAC reset from the RRC layer.

When a time period is managed by the RRC layer, the RRC layer may report or indicate, to the MAC layer, stop of the TA timer of the user equipment <NUM> (e.g., MAC reset).

Furthermore, when a time period is managed by the RRC layer, the RRC layer may modify setting of whether the TA timer of the user equipment <NUM> is to be stopped or not stopped or an amount of delay of the timing for the user equipment <NUM> to stop the TA timer depending on an RRC state of the user equipment <NUM> (e.g., a RRC CONNECTED state, an RRC IDLE state, or an RRC INACTIVE state). Here, in the RRC IDLE state, the user equipment <NUM> does not have a cell-level identification in the base station <NUM> and does not retain the context of the user equipment <NUM> in the base station <NUM>. The context of the user equipment <NUM> retained in the core network. In the RRC INACTIVE state, the user equipment <NUM>, the base station <NUM>, and the network retain the context of the RRC and the NAS (Non Access Stratum). However the state of the user equipment <NUM> is almost the same as that of the RRC IDLE, so that power consumption is expected to be reduced. In the RRC CONNECTED state, the user equipment <NUM> is identifiable at the cell level within the base station <NUM> and retains the context of the user equipment <NUM> at the base station <NUM>. When a time period is managed by the RRC layer, the RRC layer may modify setting of whether the TA timer of the user equipment <NUM> is stopped, or modify an amount of delay at which the TA timer of the user equipment <NUM> is stopped, depending on the type of random access procedure (e.g., random access procedure for the CCCH SDU, any other random access procedure).

For example, if the state of the user equipment <NUM> is in the RRC IDLE state or the RRC INACTIVE state, the RRC layer may stop the TA timer of the user equipment <NUM> after a time period from the success of the CBRA. If the state of the user equipment <NUM> is RRC CONNECTED, the RRC layer may not stop the TA timer of the user equipment <NUM> (which may be considered as a time period = infinity). However, even if the status of the user equipment <NUM> is in the RRC IDLE state or the RC INACTIVE state, the RRC layer may not stop the TA timer of the user equipment <NUM> if the status of the user equipment <NUM> may become the RRC CONNECTED subsequently (e.g., when SI request and RC connection (or request) request are executed simultaneously).

The time period may be the time interval between the receipt of a PDCCH or PDSCH including a content solution message and the transmission of the corresponding acknowledgement information. For example, a time period may be <NUM>, as in the case of an LTE. Alternatively, a time period may be the time from the receipt of a PDCCH or PDSCH including a content solution message to the transmission timing of the acknowledgement information notified by the slot length, Downlink Control Information (DCI), or the RRC layer. Alternatively, the time may be the maximum (e.g., <NUM>) or minimum value of time from the receipt of a PDCCH or PDSCH including a content solution message to the timing of transmission of the acknowledgement information assumed in the specification or a configuration.

Furthermore, when a Repetition is applied to the PDCCH, PDSCH, or acknowledgement information, a time period may be from the first transmission timing (or the first reception timing at the user equipment <NUM>) from the base station <NUM> of the PDCCH or PDSCH to the last ACK transmission timing by the user equipment <NUM>.

The time period may also be a configured value of the content solution timer. Alternatively, the time period may be the minimum value of the configured range of the content solution timer or the maximum value of the configured range of the content solution timer.

The time period may also be the pending period at a time of the RRC connection release.

In addition, an offset value (e.g., equivalent to a processing delay time) may be added to each of the above-described time periods.

As an alternative method for solving the above-described problem, even if a CBRA for an SI request is completed, the user equipment <NUM> does not autonomously stop the TA timer of the user equipment <NUM>, and the user equipment <NUM> may stop the TA timer of the user equipment <NUM> at a timing of starting a next random access procedure. In the following, details of this method are described by referring to <FIG>.

<FIG> is a diagram illustrating an example of a method in which a user equipment stops a TA timer at a start of a next random access procedure. At step S701, the user equipment <NUM> starts a CBRA for an SI request. At time T1, the user equipment <NUM> transmits Message1 (RA preamble) to the base station <NUM> (step S703). In response to receiving Message <NUM>, the base station <NUM> transmits Message2 (RAR) to the user equipment <NUM> at time T2 (Step S705). In response to receiving Message2, the user equipment <NUM> transmits Message3 (SI request) to the base station <NUM> at time T3 (Step S707). In response to receiving Message <NUM>, the base station <NUM> transmits Message <NUM> (content solution message) to the user equipment <NUM> at time T4 (step S709). In response to receiving Message <NUM>, the user equipment <NUM> completes the transmission of the acknowledgement information for Message4 to the base station <NUM> at time T5 (Step S711). Subsequently, the user equipment <NUM> stops the TA timer of the user equipment <NUM> at a start of the next random access procedure.

According to this method, the user equipment <NUM> always stops (or MAC resets) the TA timer of the user equipment <NUM> at each start of a random access procedure (or an RRC procedure, such as an RRC connection request or RC connection resume).

In the above-described method <NUM> and method <NUM>, the TA timer of the user equipment <NUM> may be considered stopped or expired.

Furthermore, the user equipment <NUM> may report, to the base station <NUM>, the UE capability related to a function to suspend stop of the TA timer of the user equipment <NUM>. In addition, as a method of reporting the UE capability from the user equipment <NUM> to the base station <NUM>, a maximum value of the time during which stop of the TA timer of the user equipment <NUM> can be suspended may be reported. For example, the capability of the user equipment <NUM> that is unable to suspend stop of the TA timer of the user equipment <NUM> may be reported as capability = <NUM>.

Next, an example of a functional configuration of the user equipment <NUM> and the base station <NUM> that execute the process operation described above is described. Each of the user equipment <NUM> and the base station <NUM> is provided with all of the functions described in the embodiments. However, each of the user equipment <NUM> and the base station <NUM> may include only a part of the functions described in the embodiments. The user equipment <NUM> and the base station <NUM> may be collectively referred to as a communication device.

<FIG> is a diagram illustrating an example of a functional configuration of the user equipment <NUM>. As illustrated in <FIG>, the user equipment <NUM> includes a transmitter <NUM>, a receiver <NUM>, a controller <NUM>, and a timer <NUM>. The functional configuration shown in <FIG> is merely one example. If the operation according to the present embodiment can be executed, functional divisions and names of functional units may be any divisions and names.

The transmitter <NUM> generates a transmission signal from transmission data and wirelessly transmits the transmission signal. The receiver <NUM> wirelessly receives a various types of signals and retrieves a higher layer signal from the received physical layer signal. The receiver <NUM> includes a measuring unit that performs measurement of the received signal and obtains the received power, etc..

The controller <NUM> controls the user equipment <NUM>. The function of the controller <NUM> related to the transmission may be included in the transmitter <NUM>, and the function of the controller <NUM> related to the reception may be included in the receiver <NUM>. The timer <NUM> is a timer utilized by the controller <NUM> to control the length of time that the user equipment <NUM> maintains the time alignment (Time Alignment) of the transmission timing of an uplink signal. The timer <NUM> operates (runs) after start, until stop, or until expire (expire), and otherwise does not operate. When the timer <NUM> is not running, the controller <NUM> may start the timer <NUM>. When the timer <NUM> is running, the controller <NUM> may restart the timer <NUM>. The timer <NUM> is always started or restarted from an initial value of the timer <NUM>. The timer <NUM> may be implemented, for example, as a counter. However, the method of implementing the timer <NUM> is not particularly limited in this specification.

When a random access procedure is started in the user equipment <NUM>, the transmitter <NUM> of the user equipment <NUM> selects a resource for transmitting a random access preamble and transmits the random access preamble to the base station <NUM> using the resource.

The receiver <NUM> receives a random access response transmitted from the base station <NUM> in response to receiving a random access preamble. In response to the receipt of the random access response by the receiver <NUM>, the controller <NUM> starts the timer <NUM>. In response to receiving random access response by the receiver <NUM>, the controller <NUM> causes the transmitter <NUM> to transmit Message3 including an SI request to the base station <NUM>.

The receiver <NUM> receives a content solution message transmitted from the base station <NUM> in response to receiving Message <NUM> including an SI request. In response to receiving a content solution message by the receiver <NUM>, the controller <NUM> causes the transmitter <NUM> to transmit acknowledgement information, and then the controller <NUM> stops the timer <NUM>. Alternatively, the controller <NUM> may cause the transmitter <NUM> to transmit the acknowledgement information, and thereafter, the timer <NUM> may be stopped at a start of a next random access procedure while the timer <NUM> is kept running.

<FIG> is a diagram illustrating an example of a functional configuration of the base station <NUM>. As shown in <FIG>, the base station <NUM> includes a transmitter <NUM>, a receiver <NUM>, a controller <NUM>, and a timer <NUM>. The functional configuration shown in <FIG> is merely an example. If the operation according to the present embodiment can be executed, functional divisions and names of functional units may be any divisions and names.

The transmitter <NUM> includes a function for generating a signal to be transmitted to the user equipment <NUM> and wirelessly transmitting the signal. The receiver <NUM> includes a function for receiving various signals transmitted from the user equipment <NUM> and retrieving information of a higher layer, for example, from the received signal. The receiver <NUM> includes a measuring unit that performs measurement of the received signal and obtains the received power, etc..

The controller <NUM> controls the base station <NUM>. The function of the controller <NUM> related to the transmission may be included in the transmitter <NUM>, and the function of the controller <NUM> related to the reception may be included in the receiver <NUM>. The timer <NUM> is a timer utilized by the controller <NUM> to control the length of time that the base station <NUM> maintains the timing of transmission of uplink signals transmitted from the user equipment <NUM>. The timer <NUM> operates (run) after start, until stop, or until expire (expire), and otherwise does not operate. When the timer <NUM> is not running, the controller <NUM> can start the timer <NUM>. When the timer <NUM> is running, the controller <NUM> may restart the timer <NUM>. The timer <NUM> is always started or restarted from the initial value of the timer <NUM>. The timer <NUM> may be implemented, for example, as a counter, but the method of implementing the timer <NUM> is not particularly limited in this specification.

The block diagrams (<FIG>) used in the description of the above-described embodiments illustrate blocks in units of functions. These functional blocks (components) are implemented by any combination of hardware and/or software. Furthermore, the means for implementing each functional block is not particularly limited. That is, each functional block may be implemented by one device with a physical and/or logical combination of elements, or may be implemented by two or more devices while directly and/or indirectly (e.g., wired and/or wireless) connecting the two or more devices that are physically and/or logically separated.

For example, each of the user equipment <NUM> and the base station <NUM> according to one embodiment of the present invention may function as a computer performing the process according to this embodiments. <FIG> is a diagram illustrating an example of a hardware configuration of a user equipment <NUM> and a base station <NUM> according to the embodiment. Each of the above-described user equipment <NUM> and base station <NUM> may be physically configured as a computer device including a processor <NUM>, a memory <NUM>, a storage <NUM>, a communication device <NUM>, an input device <NUM>, an output device <NUM>, a bus <NUM>, etc..

In the following description, the term "device" can be read as a circuit, a device, a unit, etc. The hardware configuration of the user equipment <NUM> and base station <NUM> may be configured to include one or more of the devices denoted by <NUM>-<NUM> in the figure, or may be configured without some devices.

Each function of the user equipment <NUM> and the base station <NUM> is implemented by loading predetermined software (program) on hardware, such as the processor <NUM> and the memory <NUM>, so that the processor <NUM> performs computation and controls communication by the communication device <NUM>, and reading and/or writing of data in the memory <NUM> and the storage <NUM>.

The processor <NUM>, for example, operates an operating system to control the entire computer. The processor <NUM> may be configured with a central processing unit (CPU: Central Processing Unit) including an interface with a peripheral device, a control device, a processing device, a register, etc..

Additionally, the processor <NUM> reads a program (program code), a software module or data from the storage <NUM> and/or the communication device <NUM> to the memory <NUM>, and executes various processes according to these. As the program, a program is used which causes a computer to execute at least a part of the operations described in the above-described embodiment. For example, the transmitter <NUM>, the receiver <NUM>, the controller <NUM>, and the timer <NUM> of the user equipment <NUM> illustrated in <FIG> may be implemented by a control program that is stored in the memory <NUM> and operated by the processor <NUM>. For example, the transmitter <NUM>, the receiver <NUM>, the controller <NUM>, and the timer <NUM> of the base station <NUM> illustrated in <FIG> may be implemented by a control program stored in the memory <NUM> and operated by the processor <NUM>. While the various processes described above are described as being executed in one processor <NUM>, they may be executed simultaneously or sequentially by two or more processors <NUM>. Processor <NUM> may be implemented by one or more chips. The program may be transmitted from the network via a telecommunications line.

The memory <NUM> is a computer readable storage medium, and, for example, the memory <NUM> may be formed of at least one of a ROM (Read Only Memory), an EPROM (Erasable Programmable ROM), an EEPROM (Electrically Erasable Programmable ROM), a RAM (Random Access Memory), etc. The memory <NUM> may be referred to as a register, a cache, a main memory (main storage device), etc. The memory <NUM> may store a program (program code), a software module, etc., which can be executed for implementing the process according to one embodiment of the present invention.

The storage <NUM> is a computer readable storage medium and may be formed of, for example, at least one of an optical disk, such as a CD-ROM (Compact Disc ROM), a hard disk drive, a flexible disk, an optical magnetic disk (e.g., a compact disk, a digital versatile disk, a Blu-ray (registered trademark) disk, a smart card, a flash memory (e.g., a card, a stick, a key drive), a floppy (registered trademark) disk, a magnetic strip, etc. The storage <NUM> may be referred to as an auxiliary storage device. The above-described storage medium may be, for example, a database including memory <NUM> and/or storage <NUM>, a server, or any other suitable medium.

The communication device <NUM> is hardware (transmitting and receiving device) for performing communication between computers through a wired and/or wireless network, and is also referred to, for example, as a network device, a network controller, a network card, a communication module, etc. For example, the transmitter <NUM> and the receiver <NUM> of the user equipment <NUM> may be implemented by the communication device <NUM>. The transmitter <NUM> and the receiver <NUM> of the base station <NUM> may be implemented by the communication device <NUM>.

The input device <NUM> is an input device (e.g., a keyboard, a mouse, a microphone, a switch, a button, a sensor, etc.) that receives an external input. The output device <NUM> is an output device (e.g., a display, speaker, LED lamp, etc.) that performs output toward outside. The input device <NUM> and the output device <NUM> may be configured to be integrated (e.g., a touch panel).

Each device, such as processor <NUM> and memory <NUM>, is also connected by the bus <NUM> for communicating information. The bus <NUM> may be formed of a single bus or may be formed of different buses between devices.

User equipment <NUM> and base station <NUM> may each include hardware, such as a microprocessor, a digital signal processor (DSP), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), and a FPGA (Field Programmable Gate Array), which may implement some or all of each functional block. For example, processor <NUM> may be implemented by at least one of these hardware components.

As described above, according to the embodiments, there is provided user equipment 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 in a time interval during which timing for transmitting an uplink signal from the user equipment is maintained, wherein, in response to receiving the random access response by the receiver, the controller activates the timer, and the controller causes the transmitter to transmit a message <NUM> including a message requesting transmission of system information to the base station, and wherein the controller stops the timer after a time period has elapsed from reception, by the receiver, of a contention resolution message transmitted from the base station. Here, "maintaining timing" may imply holding the timing, may imply controlling the timing, may imply adjusting the timing, or may imply setting the timing. According to the user equipment, a method of acquiring system information based on message <NUM> can be provided with which the user equipment can appropriately execute a random access procedure.

The time period may be any one of a time interval from the reception, by the receiver, of the contention resolution message transmitted from the base station in response to the receipt of the message <NUM> until the controller causes the transmitter to transmit acknowledgement information for the contention resolution message; a time interval from the reception, by the receiver, of the contention resolution message to a radio frame immediately after a radio frame at a timing at which the controller causes the transmitter to transmit the acknowledgement information for the contention resolution message; a time interval from the reception, by the receiver, of the contention resolution message to a subframe immediately after a subframe at the timing at which the controller causes the transmitter to transmit the acknowledgement information for the contention resolution message; a time interval from the reception, by the receiver, of the contention resolution message to a slot immediately after a slot at the timing at which the controller causes the transmitter to transmit the acknowledgement information for the contention resolution message; a time interval from the reception, by the receiver, of the contention resolution message to a symbol immediately after a symbol at the timing at which the controller causes the transmitter to transmit the acknowledgement information for the contention resolution message; and <NUM>. As a result, while securing a degree of freedom for the timing to stop the timer, the user equipment can be ensured to transmit the acknowledgement information for the contention resolution message.

The time period may be maintained by a Medium Access Control (MAC) layer or a Radio Resource Control (RRC) layer. According to this configuration, in addition to autonomously stopping the timer by the MAC upon expiration of the timer, setting of whether the timer is stopped or not stopped or an amount of delay of the timing to stop the timer can be modified depending on an RRC state of the user equipment (UE). Alternatively, the MAC layer may also apply a different operation or delay amount for each RRC state by implicitly determining, by the MAC layer, whether the SI request is an SI request of which the RRC state of the user equipment is an RRC CONNECTED state, or an SI request of which the RRC state of the user equipment is an RRC IDLE state or an RRC INACTIVE state. For example, if an SI request is transmitted by a CCCH SDU, the MAC layer may determine that the RRC state of the user equipment is the RRC IDLE state or the RRC INACTIVE state. If an SI request is transmitted on a Dedicated Control Channel (DCCH) (through a Signaling Radio Bear (SRB) for transmitting DCCH data), the RRC state of the user equipment may be determined to be the RRC CONNECTED state.

When the time period is maintained by the RRC layer, the RRC layer may modify setting of whether the timer is stopped, or the RRC layer may modify a delay amount of the timing to stop the timer, in accordance with the RRC state of the user equipment. As a result, if another RRC procedure is not started, the timer can be caused not to stop.

When the time period is maintained by the RRC layer, upon detecting that an RRC state of the user equipment is an RRC IDLE state or an RRC INACTIVE state, the controller may stop the timer after the time period has elapsed from the reception, by the receiver, of the contention resolution message, and, upon detecting that the RRC state of the user equipment is an RRC CONNECTED state, the controller may prevent the timer from being stopped. As a result, if another RRC procedure is not started, the timer can be caused not to stop.

The time period may be a timer interval from the reception, by the receiver, of the contention resolution message transmitted from the base station in response to the reception of the message <NUM> until a time to start a next RRC procedure. As a result, when a random access procedure is executed and, subsequently, a next random access procedure is executed, the user equipment can be caused to execute the random access procedures appropriately.

While the embodiments of the present invention are described above, the disclosed invention is not limited to the embodiments, and those skilled in the art will appreciate various alterations, modifications, alternatives, substitutions, etc. Descriptions are provided using specific numerical examples to facilitate understanding of the invention, but, unless as otherwise specified, these values are merely examples and any suitable value may be used. Classification of the items in the above descriptions is not essential to the present invention, and the items described in two or more items may be used in combination as needed, or the items described in one item may be applied (unless inconsistent) to the items described in another item. The boundaries of functional units or processing units in the functional block diagram do not necessarily correspond to the boundaries of physical components. An operation by a plurality of functional units may be physically performed by one component or an operation by one functional unit may be physically executed by a plurality of components. For the processing procedures described in the embodiment, the order of processing may be changed as long as there is no inconsistency. For the convenience of the description of the process, the user equipment <NUM> and the base station <NUM> are described using functional block diagrams, but such devices may be implemented in hardware, software, or a combination thereof. Software operated by a processor in accordance with embodiments of the present invention and software operated by a processor in accordance with embodiments of the present invention may be stored in a random access memory (RAM), a flash memory (RAM), a read-only memory (ROM), an EPROM, an EEPROM, a register, a hard disk (HDD), a removable disk, a CD-ROM, a database, a server, or any other suitable storage medium, respectively.

Notification of information is not limited to the aspects/embodiments described in this specification, and notification of information may be made by another method. For example, notification of information may be implemented by physical layer signaling (e.g., DCI (Downlink Control Information), UCI (Uplink Control Information), higher layer signaling (e.g., RRC (Radio Resource Control) signaling, MAC (Medium Access Control) signaling, broadcast information (MIB (Master Information Block), SIB (System Information Block))), or other signals or combinations thereof. RRC signaling may be referred to as an RRC message, for example, which may be an RRC connection setup message, an RRC connection reconfiguration (RRC Connection Connection Connection), etc..

The aspects/embodiments described in this specification may be applied to a system using LTE (Long Term Evolution), LTE-A (LTE-Advanced), SUPER <NUM>, IMT-Advanced, <NUM>, <NUM>, FRA (Future Radio Access), W-CDMA (Registered Trademark), GSM (Registered Trademark), CDMA2000, UMB (Ultra Mobile Broadband), IEEE <NUM> (Wi-Fi), IEEE <NUM> (WiMAX), IEEE <NUM>, UWB (Ultra-WideBand), Bluetooth (Registered Trademark), or any other appropriate system, and/or a next generation system extended based on theses.

The processing procedures, sequences, flow charts, etc. of each aspect/embodiment described herein may be reordered, provided that there is no contradiction. For example, the methods described in this specification present elements of various steps in an exemplary order and are not limited to the particular order presented.

The particular operation described in this specification to be performed by base station <NUM> may be performed by an upper node in some cases. It is apparent that in a network consisting of one or more network nodes having base stations <NUM>, various operations performed for communicating with user equipment <NUM> may be performed by base stations <NUM> and/or other network nodes other than base stations <NUM> (e.g., MME or S-GW can be considered, however, the network node is not limited to these). The case is exemplified above in which there is one network node other than the base station <NUM>. However, the network node other than the base station <NUM> may be a combination of multiple other network nodes (e.g., MME and S-GW).

The aspects/embodiments described in this specification may be used alone, may be used in combination, or may be switched during execution.

The user equipment <NUM> may be referred to by one of ordinary skill in the art as a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terms.

The base station <NUM> may be referred to by one of ordinary skill in the art as NB (NodeB), eNB (enhanced NodeB), base station (Base Station), gNB, or some other suitable terms.

The terms "determine (determining)" and "decide (determining)" used in this specification may include various types of operations. For example, "determining" and "deciding" may include deeming that a result of calculating, computing, processing, deriving, investigating, looking up (e.g., search in a table, a database, or another data structure), or ascertaining is determined or decided. Furthermore, "determining" and "deciding" may include, for example, deeming that a result of receiving (e.g., reception of information), transmitting (e.g., transmission of information), input, output, or accessing (e.g., accessing data in memory) is determined or decided. Furthermore, "determining" and "deciding" may include deeming that a result of resolving, selecting, choosing, establishing, or comparing is determined or decided. Namely, "determining" and "deciding" may include deeming that some operation is determined or decided.

The phrase "based on" used in this specification does not imply "based solely on" unless otherwise specified. In other words, "based on" means both "based solely on" and "at least based on.

The terms "include (include)" "including (including)," and variants thereof are used in this specification or in the claims, these terms are intended to be inclusive, similar to the term "comprising. " Furthermore, it is intended that the term "or" as used in this specification or in the claims is not an exclusive logical sum.

Throughout the present disclosure, if an article is added by translation, such as "a," "an", and "the" in English, these articles may include a plurality of things unless as otherwise indicated by the context clearly.

Claim 1:
A terminal (<NUM>) configured to perform a contention based random access procedure for system information, SI, request, comprising:
a receiver (<NUM>) configured to receive, from a base station (<NUM>), a random access response, RAR, including a Timing Advance command; and
a controller (<NUM>) configured to control a timeAliqnment timer, TA timer, for uplink time alignment,
wherein, in response to receiving the Timing Advance command in the RAR, the controller is configured to start the TA timer, and
wherein, upon receiving from the base station (<NUM>), by the receiver, a contention resolution message, the controller is configured to stop the TA timer after transmitting, by a transmitter (<NUM>) of the terminal (<NUM>) to the base station (<NUM>), acknowledgement information for the contention resolution message.