Wireless terminals, wireless access network nodes, and methods thereof

Abstract

A wireless terminal (1) determines whether or not access by the wireless terminal (1) to a serving cell (21) is to be barred, by comparing the wireless state of the serving cell (21) to the wireless state of an adjacent cell (31) of the same frequency band as the serving cell (21). This invention can contribute to, for example, providing an access barring method suitable for a wireless terminal located at a cell boundary between a serving cell and an adjacent cell which use the same frequency band.

Description

[Technical Field]

[0001] This disclosure relates to wireless communication networks, and in particular to the regulation of access to serving cells by wireless terminals. [Background technology]

[0002] The 3rd Generation Partnership Project (3GPP®) standards introduce several techniques for implementing restrictions or barring of access to cells by wireless terminals (i.e., User Equipment (UEs)). Access barring allows Radio Access Network (RAN) nodes (e.g., eNBs, gNBs) to bar access from some of the UEs camped on a cell when the cell is under heavy load. When access barring is enabled, UEs do not initiate the establishment or resumption of Radio Resource Control (RRC) connections for all access causes except mobile terminated calls. These access barring techniques include, for example, Access Class Barring (ACB), Extended Access Barring (EAB), Application specific Congestion control for Data Communication (ACDC), and Unified Access Control (UAC). Of these, EAB distinguishes Machine-Type Communications (MTC) devices and Internet of Things (IoT) devices from regular (or legacy) UEs, and enables special access barring for MTC and IoT devices.

[0003] Furthermore, a Coverage Enhancement (CE) level-based access barring mechanism was introduced in 3GPP Release 15, allowing Radio Access Network (RAN) nodes (e.g., eNBs, gNBs) to bar access at each CE level. Specifically, when a cell is under heavy load, a RAN node can bar access from UEs belonging to a certain CE level and all CE levels higher than that. UEs at higher CE levels can be associated with high resource consumption due to tens, hundreds, or even thousands of repetitions. Therefore, barring access from UEs at higher CE levels can contribute to reducing cell load.

[0004] Current 3GPP standards support up to four CE levels (i.e., CE levels 0 to 3). UEs determine their CE level based on the measured Reference Signal Received Power (RSRP) level. CE level 0 is associated with the highest RSRP threshold, and CE level 3 is associated with the lowest RSRP threshold. In other words, UEs at CE level 0 enjoy relatively low path loss and high received power, while UEs at CE level 3 enjoy relatively high path loss and low received power.

[0005] Sections 5.3.3.12 and 5.3.3.14 of Non-Patent Document 1 specify CE level-based access barring. Specifically, a RAN node can broadcast control information (i.e., eab-PerRSRP) regarding access barring per RSRP within a cell via system information (i.e., System Information Block Type 14 (SIB14)). eab-PerRSRP represents thresh0, thresh1, thresh2, or thresh3. If eab-PerRSRP is set to the value thresh0, the UE considers access to the cell to be prohibited when enhanced coverage is enabled. If eab-PerRSRP is set to the value thresh1, the UE considers access to the cell to be prohibited if the measured RSRP is less than the first entry in rsrp-ThresholdsPrachInfoList. Similarly, if eab-PerRSRP is set to the value thresh2, the UE considers access to the cell to be prohibited if the measured RSRP is less than the second entry in rsrp-ThresholdsPrachInfoList. If eab-PerRSRP is set to the value thresh3, the UE considers access to the cell to be prohibited if the measured RSRP is less than the third entry in rsrp-ThresholdsPrachInfoList. Note that rsrp-ThresholdsPrachInfoList is included in the PRACH-Config information element and is broadcast in the cell via system information (i.e., SIB type 2 (SIB2)).

[0006] These access barring techniques restrict UEs from accessing serving cells to receive dedicated services. In particular, when a UE is RRC_IDLE or RRC_INACTIVE, its serving cell can be said to be a cell to which the UE is camped. A serving cell is sometimes called a camped cell. A UE that is RRC_IDLE or RRC_INACTIVE will camp on to a cell once it has selected a suitable cell to camp on to according to the cell selection criteria or cell reselection criteria. Camping on to a cell means that the UE has completed the cell selection or reselection process and selected a cell. In other words, the term "camp on" means that the UE is staying in a cell and is ready to initiate potential dedicated services in that cell. After camping on to a cell according to the cell selection or reselection procedure, the UE performs an access barring check before accessing the camped cell (i.e., the serving cell). Access barring allows you to prevent intended UEs from sending initial access messages for load control purposes.

[0007] Therefore, the method for access barring is not used for controlling the cell selection and reselection procedures of UEs. When selecting a cell to camp on, UEs ignore access barring. In other words, in the cell selection or reselection procedure, UEs cannot reject the cell to camp on because access to that cell is not permitted based on access barring. For example, access barring needs to be checked by the UE before transmitting the first RRC message (e.g., RRC CONNECTION REQUEST message, RRC Setup Request message, or RRC Resume Request message) when the UE enters the RRC_CONNECTED mode from the RRC_IDLE (or RRC_INACTIVE) mode.

[0008] Incidentally, the 3GPP Radio Access Network (RAN) Working Group is currently considering New Radio (NR) support for Reduced Capability (RedCap) UEs, and this feature is scheduled to be introduced in 3GPP Release 17 (see, for example, Non-Patent Document 2). The introduction of RedCap NR devices will enable the addressing of use cases not yet optimally provided by the current NR standard. Use cases that motivate the NR RedCap standardization work include wearables (e.g., smart watches, wearable medical devices, Augmented Reality (AR) / Virtual Reality (VR) goggles), industrial wireless sensors, and video surveillance. These use cases have less stringent data rate requirements than enhanced mobile broadband (eMBB) use cases and do not require the tight or deterministic latency requirements of time-critical communications use cases. Therefore, there is room to trade off device features for complexity or cost reduction compared to the baseline Release 15 NR device. According to the currently envisioned capabilities of RedCap devices, the maximum device bandwidth, minimum number of device receive branches, maximum number of downlink MIMO layers, and maximum downlink modulation order are reduced or relaxed compared to those of Release 15 NR devices.

[0009] Non-Patent Document 3 presents issues related to cell selection and reselection of RedCap UEs. According to the current consensus, not all cells permit camping-on by RedCap UEs. Consider a case where only one of two cells in the same frequency band adjacent to each other permits camping-on by RedCap UEs. If the cell with the highest rank in terms of received quality level (the highest ranked cell) does not permit camping-on by RedCap UEs, the RedCap UEs may camp-on the other cell (e.g., the second highest ranked cell). In this case, the RedCap UEs may be interfered with by an adjacent cell that has the highest rank in terms of received quality level but does not permit camping-on by RedCap UEs. Therefore, Non-Patent Document 3 states that it is necessary to discuss solutions to potential interference issues of RedCap UEs.

Prior Art Documents

Non-Patent Documents

[0010]

Non-Patent Document 1

Non-Patent Document 2

[0011] The inventors investigated barring or restricting access to serving cells by UEs and identified various challenges.

[0012] One of these challenges concerns networks where not all cells allow RedCap UEs to camp on. Consider a case where only one of two adjacent cells in the same frequency band allows RedCap UEs to camp on. If the cell with the highest received quality level (the highest ranked cell) does not allow RedCap UEs to camp on, then the RedCap UEs may camp on the other cell (e.g., the second highest ranked cell). In this case, the RedCap UEs' access to the serving cell could cause interference problems with legacy UEs. For example, RedCap UEs' access (or uplink transmission) to a serving cell could interfere with legacy UEs' access (or uplink transmission) to an adjacent cell where the adjacent cell is the serving cell. Non-patent document 3 states that solutions to the potential interference problem of RedCap UEs need to be discussed, but does not provide any concrete solutions.

[0013] Another of these challenges concerns access barring to allow low-mobility UEs to access cells. ACB provides barring based on access classes. Access classes are identifiers assigned to each user by the network operator to indicate access priority and are stored in the Subscriber Identity Module (SIM). EAB enables barring targeting MTC and IoT devices. ACDC enables selective barring of access attempts from specific applications. UAC provides access barring based on access identifiers. Access identifiers are determined by the UE based on the access class and access type (e.g., Mobile Terminated (MT) Access, Emergency, Delay Tolerant Service, Mobile Originated Multimedia Telephony Voice, Mobile Originated Multimedia Telephony Video, etc.). However, these existing access barring methods cannot restrict UE access to serving cells based on the UE's mobility level.

[0014] One of the objectives that the embodiments disclosed herein seek to achieve is to provide apparatus, methods, and programs that contribute to solving at least one of several problems relating to the barring or restriction of access to serving cells by UEs, including the problems described above. It should be noted that this objective is only one of several objectives that the embodiments disclosed herein seek to achieve. Other objectives or problems and novel features will be evident from the description herein or from the accompanying drawings. [Means for solving the problem]

[0015] In a first embodiment, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to determine whether access to the serving cell by the wireless terminal is barred by comparing the radio state of the serving cell with the radio state of an adjacent cell in the same frequency band as the serving cell.

[0016] In a second embodiment, the method performed by the wireless terminal includes determining whether access to the serving cell by the wireless terminal is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell.

[0017] In a third embodiment, a radio access network (RAN) node includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to broadcast a threshold information element in a first cell. The threshold is used by a radio terminal using the first cell as a serving cell to determine whether access to the serving cell is barred by comparing the radio state of the serving cell with the radio state of an adjacent cell in the same frequency band as the serving cell.

[0018] In a fourth embodiment, the method performed by the RAN node includes broadcasting an information element indicating a threshold in a first cell. The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell.

[0019] In a fifth embodiment, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to determine whether access by the wireless terminal to the serving cell is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell.

[0020] In a sixth embodiment, the method performed by the wireless terminal includes determining whether access to the serving cell by the wireless terminal is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell.

[0021] In a seventh embodiment, the RAN node includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to broadcast a threshold information element in a first cell. The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell.

[0022] In the eighth aspect, the method performed by the RAN node includes broadcasting an information element indicating a threshold in the first cell. The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell.

[0023] In the ninth aspect, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is SSearchThresholdP and S SearchThresholdQ is configured to receive, via broadcast, from a first cell, one or more information elements indicating one or both of them. The S SearchThresholdP is a threshold value compared with a cell selection RX level value (Srxlev) of the serving cell to determine whether the wireless terminal performs adjacent cell measurements for cell reselection when the wireless terminal uses the first cell as the serving cell. The S SearchThresholdQ is a threshold value compared with a cell selection quality value (Squal) of the serving cell to determine whether the wireless terminal performs the adjacent cell measurements for cell reselection when the wireless terminal uses the first cell as the serving cell. The at least one processor is also configured to use one or both of the S SearchThresholdP and the S SearchThresholdQ to determine whether access by the wireless terminal to the serving cell is prohibited (barred) when the wireless terminal uses the first cell as the serving cell.

[0024] In a tenth aspect, a method performed by a wireless terminal includes the following steps: (a) receiving, via broadcast, from a first cell, one or more information elements indicating one or both of S SearchThresholdP and S SearchThresholdQ , where the S is a threshold value compared with a cell selection RX level value (Srxlev) of the serving cell to determine whether the wireless terminal performs adjacent cell measurements for cell reselection when the wireless terminal uses the first cell as the serving cell, SearchThresholdP and the S is a threshold value compared with a cell selection quality value (Squal) of the serving cell to determine whether the wireless terminal performs the adjacent cell measurements for cell reselection when the wireless terminal uses the first cell as the serving cell; and SearchThresholdQ (b) In order to determine whether access by the wireless terminal to the serving cell is barred when the wireless terminal is using the first cell as the serving cell, the S SearchThresholdP and the aforementioned S SearchThresholdQ Use one or both of them.

[0025] In the eleventh embodiment, the wireless terminal includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to determine whether the wireless terminal's access to the serving cell is barred based on the amount of data stored in the wireless terminal's uplink buffer.

[0026] In a twelfth aspect, the method performed by the wireless terminal includes determining whether the wireless terminal's access to the serving cell is barred based on the amount of data stored in the wireless terminal's uplink buffer.

[0027] In a thirteenth embodiment, the RAN node includes at least one memory and at least one processor coupled to the at least one memory. The at least one processor is configured to broadcast a threshold information element in a first cell. The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell by the wireless terminal is barred, based on the amount of data stored in the wireless terminal's uplink buffer.

[0028] In a fourteenth aspect, the method performed by the RAN node includes broadcasting an information element indicating a threshold in a first cell. The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell by the wireless terminal is barred, based on the amount of data stored in the wireless terminal's uplink buffer.

[0029] The 15th aspect is directed to a program, which, when loaded into a computer, includes a set of instructions (software code) for causing the computer to perform the methods relating to the 2nd, 4th, 6th, 8th, 10th, 12th, or 14th aspects described above. [Effects of the Invention]

[0030] According to the embodiments described above, it is possible to provide an apparatus, method, and program that contribute to solving at least one of several problems relating to barring or restricting access to serving cells by UEs. [Brief explanation of the drawing]

[0031] [Figure 1] This figure shows an example configuration of a wireless communication system according to the embodiment. [Figure 2] This figure shows an example of a protocol stack for the control plane of a wireless terminal according to the embodiment. [Figure 3] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 4] This figure shows an example of an operation related to access bar ringing performed by a wireless terminal according to the embodiment. [Figure 5] This figure shows an example of an operation related to access bar ringing performed by a wireless terminal according to the embodiment. [Figure 6] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 7] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 8] This flowchart shows an example of the operation of a wireless terminal according to the embodiment. [Figure 9] This is a block diagram showing an example configuration of a wireless terminal according to the embodiment. [Figure 10] This is a block diagram showing an example configuration of a RAN node according to the embodiment. [Modes for carrying out the invention]

[0032] The following describes specific embodiments in detail with reference to the drawings. In each drawing, the same or corresponding elements are denoted by the same reference numerals, and redundant explanations are omitted where necessary for clarity.

[0033] The multiple embodiments described below can be implemented independently or in combination as appropriate. These multiple embodiments have novel features that differ from each other. Therefore, these multiple embodiments contribute to solving different objectives or problems and contribute to producing different effects.

[0034] The following embodiments are described primarily with reference to 3GPP fifth-generation mobile communication systems (5G systems). However, these embodiments may also be applicable to other wireless communication systems.

[0035] As used herein, depending on the context, “(if)” may be interpreted as meaning “when,” “at or around the time,” “after,” “upon,” “in response to determining,” “in accordance with a determination,” or “in response to detecting.” These expressions may be interpreted as having the same meaning depending on the context.

[0036] <First Embodiment> Figure 1 shows an example configuration of a wireless communication system according to several embodiments, including this embodiment. In the example in Figure 1, the wireless communication system includes a wireless terminal (ie, UE) 1, a wireless access network (RAN) node (eg, gNB) 2, and a RAN node 3. Each element (network function) shown in Figure 1 can be implemented, for example, as a network element on dedicated hardware, as a running software instance on dedicated hardware, or as an instantiated virtualization function on an application platform.

[0037] UE1 has at least one radio transceiver and is configured to communicate cellularly with RAN node 2. UE1 may be a Reduced Capability (RedCap) UE. RedCap UEs have limited capabilities compared to those of legacy UEs (e.g., Release 15 NR devices as a baseline). According to the currently assumed capabilities of RedCap devices, at least one of the following may be reduced or relaxed compared to those of Release 15 NR devices: maximum device bandwidth, minimum number of device receive branches, maximum number of downlink MIMO layers, and maximum downlink modulation order. RedCap UEs operate on only one bandwidth at a time and do not necessarily support carrier aggregation and dual connectivity.

[0038] RAN node 2 manages cell 21 and is configured to communicate cellularly with multiple UEs, including UE1, using cellular communication technology (e.g., NR Radio Access Technology). RAN node 3 manages cell 31 and is configured to communicate cellularly with multiple UEs using cellular communication technology (e.g., NR Radio Access Technology).

[0039] RAN node 2 may be a Central Unit (e.g., gNB-CU) in a cloud RAN (C-RAN) deployment, or a combination of a CU and one or more Distributed Units (e.g., gNB-DUs). Similarly, RAN node 3 may be a CU, or may include a CU and one or more DUs. C-RAN is also called a CU / DU split. Furthermore, a CU may include a Control Plane (CP) Unit (e.g., gNB-CU-CP) and one or more User Plane (UP) Units (e.g., gNB-CU-UP). Therefore, each of RAN nodes 2 and 3 may be a CU-CP, or a combination of CU-CP and CU-UP. A CU may be a logical node hosting the gNB's Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and Packet Data Convergence Protocol (PDCP) protocols (or the gNB's RRC and PDCP protocols). The DU may also be a logical node that hosts the gNB's Radio Link Control (RLC), Medium Access Control (MAC), and Physical (PHY) layers.

[0040] RAN node 2 broadcasts System Information (SI) 101 into cell 21. System Information 101 includes a Master Information Block (MIB) and many System Information Blocks (SIBs). System Information 101 is divided into Minimum SI and Other SI. Minimum SI is always broadcast periodically and contains basic information necessary for initial access and information necessary to obtain Other SI. Other SI includes all SIBs that are not broadcast within Minimum SI. More specifically, Minimum SI includes MIB and SIB type 1 (SIB1), while Other SI includes SIB type 2 (SIB2) and later SIB types. Each SIB included in Other SI is either always broadcast periodically, broadcast on demand based on requests from UEs that are RRC_IDLE or RRC_INACTIVE, or sent to UEs that are RRC_CONNECTED via dedicated RRC signaling.

[0041] In the example in Figure 1, UE1 selects or re-selects cell 21 of RAN node 2 and camps on to cell 21. In other words, cell 21 is the serving cell of UE1. Cell 31, on the other hand, is a neighboring cell of UE1's serving cell 21. Cells 21 and 31 may operate in the same frequency band or in different frequency bands. Cell reservations may be imposed on cell 31 to control the cell selection and re-selection procedures. Cell reservations use control information contained in the Minimum SI (i.e., MIB and SIB1) (e.g., "CellBarred" in the MIB, or "cellReservedForOperatorUse", "cellReservedForOtherUse", or "cellReservedForFutureUse" in SIB1) to control cell selection and re-selection by UEs. The control information for cell reservation transmitted in the Minimum SI of cell 31 may indicate that cell selection or cell reselection of cell 31 by UE1 is prohibited. In addition, the Minimum SI of cell 31 (e.g., “intraFreqReselection” in the MIB) may indicate that intra-frequency reselection is permitted. In this case, UE1 will camp on to cell 21 in the same frequency band as cell 31, even if cell 31 is the highest-ranked cell according to the cell reselection criteria.

[0042] In addition to cell 31, one or more other neighboring cells may be present around cell 21. Some or all of these other neighboring cells may operate in the same frequency band as cell 21.

[0043] Figure 2 shows an example of the control plane protocol stack for UE1. The UE1 control plane protocol stack 200 includes the Application (APP) layer 201, the Non-Access Stratum (NAS) layer 202, and the Access Stratum (AS) layer 208. The AS layer 208 includes the RRC layer 203, the PDCP layer 204, the RLC layer 205, the MAC layer 206, and the PHY layer 207.

[0044] NAS layer 202 utilizes data communication and radio interface management on the radio interface provided by AS layer 208 to communicate with the core network (i.e., 5G Core (5GC)) via RAN node 2 according to the 5G System (5GS) Mobility Management (5GMM) protocol and the 5GS Session Management (5GSM) protocol. The 5GMM protocol is executed between UE1 and the Access and Mobility Management Function (AMF) in 5GC and is used for UE registration, mobility, and the transport of 5GSM protocol messages. The 5GSM protocol is executed via the AMF between UE1 and the Session Management Function (SMF) in 5GC and supports the management of PDU session connectivity.

[0045] NAS layer 202 communicates with RRC layer 203 to utilize services provided by AS layer 208 (i.e., data communication on the wireless interface between UE1 and RAN node 2 and management of the wireless interface). RRC layer 203 is a lower layer of NAS layer 202 and provides wireless resource control (RRC), managing the RRC state of UE1 (i.e., RRC_IDLE, RRC_INACTIVE, and RRC_CONNECTED).

[0046] AS layer 208 initiates an RRC connection establishment procedure or an RRC connection resumption procedure, either at the request of NAS layer 202 or spontaneously. For example, upon receiving a PDU session establishment request from a higher layer (i.e., application layer 201), NAS layer 202, if UE1's 5GS mobility management (5GMM) mode is 5GMM-IDLE, initiates a registration procedure or a service request procedure to transition to 5GMM-CONNECTED mode and attempts to send an initial NAS message (i.e., a registration request message or a service request message) to the AMF. The initial NAS message from NAS layer 202 triggers AS layer 208 to establish an RRC connection between UE1 and RAN node 2.

[0047] AS Layer 208 performs access barring checks as described below. These checks occur when UE1 accesses a cell (i.e., a serving cell) after selecting a cell to camp on during the cell selection procedure. In other words, access barring checks are not performed during the cell selection or re-selection procedure in which UE1 selects a cell to camp on. In this respect, access barring checks differ from cell reservations used to control the cell selection and re-selection procedures.

[0048] In some implementations, the RRC layer 203 may perform the access barring check. In this case, the RRC layer 203 may perform the access barring check in response to the start of an RRC connection establishment procedure or an RRC connection resumption procedure to a serving cell. The RRC layer 203 may also perform the access barring check when an upper layer (i.e., the NAS layer) requests or triggers the establishment of an RRC connection. The RRC layer 203 may also perform the access barring check when an upper layer (i.e., the NAS layer) or the RRC layer 203 requests or triggers the resumption of an RRC connection. In other implementations, the MAC layer 206 may perform the access barring check. In this case, the MAC layer 206 may perform the access barring check in response to the start of a random access procedure to a serving cell. A random access procedure is also called a Random Access Channel (RACH) procedure. The MAC layer 206 may perform the access barring check when it is triggered to start a random access procedure.

[0049] Furthermore, AS Layer 208 may perform one or more additional access barring checks. These additional access barring checks may include, but are not limited to, existing ACBs, EABs, ACDCs, or UACs, or any combination thereof, and may include barrings or restrictions(s) similar to these existing access barrings. The EAB distinguishes Machine-Type Communications (MTC) devices and Internet of Things (IoT) devices from regular (or legacy) UEs and enables special access barring for MTC and IoT devices.

[0050] Figure 3 shows an example of the operation of the access barring check performed by AS layer 208 of UE1. Here, UE1 is camp-on to cell 21. In other words, cell 21 is the serving cell of UE1. In step 301, UE1 determines whether access to the serving cell (i.e., cell 21) by UE1 is prohibited by comparing the radio state of the serving cell (i.e., cell 21) with the radio state of an adjacent cell (e.g., cell 31) in the same frequency band as the serving cell. The radio state of the serving cell may also be rephrased as, for example, the serving cell's radio quality, channel state, channel quality, downlink signal state, or downlink signal quality. If there are multiple adjacent cells in the same frequency band as the serving cell, UE1 may select the highest-ranking cell among the multiple adjacent cells for comparison according to cell reselection criteria (e.g., R criteria). Prohibition of access to the serving cell means that the establishment or reopening of an RRC connection with the serving cell is prohibited. Alternatively, prohibiting access to a serving cell means prohibiting random access to that serving cell.

[0051] If access to the serving cell is denied, UE1 terminates the procedure (step 302). In implementations where burring checks are performed at the RRC layer 203, the terminated procedure may be an RRC connection establishment procedure or an RRC connection restart procedure. If the RRC layer 203 determines that access to the serving cell is denied, it may notify the higher layer (i.e., the NAS layer) of the failure to establish or restart the RRC connection. On the other hand, in implementations where burring checks are performed at the MAC layer 206, the terminated procedure may be a random access procedure.

[0052] For example, UE1 may compare a first metric, which increases in response to improvements in the radio condition of a serving cell, with a second metric, which increases in response to improvements in the radio condition of an adjacent cell. More specifically, UE1 may determine that access to the serving cell is permitted if the value obtained by subtracting the first metric of the serving cell from the second metric of the adjacent cell is less than a threshold. In other words, UE1 may determine that access to the serving cell is prohibited if the value obtained by subtracting the first metric from the second metric exceeds a threshold. This threshold may be a positive value. That is, if the radio condition of the serving cell is lower than the radio condition of an adjacent cell in the same frequency band by a threshold, UE1 may determine that access to the serving cell is prohibited.

[0053] UE1 may receive the information element indicating the threshold from the serving cell (e.g., cell 21) via broadcast. The RAN node providing the serving cell (e.g., RAN node 2) may broadcast the information element into cell 21 via system information (e.g., SIB2). The information element may indicate an index for UE1 to derive the threshold.

[0054] The first metric described above may also relate to the received signal power or received signal quality of the serving cell's downlink signal. Similarly, the second metric may relate to the received signal power or received signal quality of the adjacent cell's downlink signal. Each of the first and second metrics may include, or be derived from, the Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or signal-to-interference-plus-noise power ratio (SINR) measured by UE1. More specifically, each of the first and second metrics may be, or be derived from, the Synchronization Signal (SS) RSRP, SS-RSRQ, or SS-SINR.

[0055] Each of the first and second metrics may be a parameter derived or calculated from the measured RSRP or RSRQ. The first metric may be the serving cell's Srxlev. Alternatively, the first metric may be the serving cell's Squal. Srxlev is the cell selection RX level value (dB). Squal is the cell selection quality value (dB). Srxlev and Squal are also parameters used in the Cell Selection Criterion (i.e., S-criterion). Srxlev is the measured RSRP value (Q) of the serving cell. rxlevmeas Squal is calculated using the measured RSRQ value (Q) of the serving cell. qualmeas ) is calculated using the following parameters: In this case, the second metric is a parameter equivalent to Srxlev or Squal calculated based on the RSRP or RSRQ of adjacent cells in the same frequency band as the serving cell (e.g., Srxlev Bestcell Squal Bestcell ) is also acceptable.

[0056] In another example, UE1 may use a third metric that increases in response to improvements in the serving cell's radio condition and decreases in response to improvements in the radio condition of neighboring cells. UE1 may determine that access to the serving cell is permitted if the third metric is greater than a threshold. The third metric may include, or be derived from, the RSRQ or SINR of the serving cell's downlink signal. More specifically, the third metric may be, or be derived from, the SS-RSRQ or SS-SINR of the serving cell. For example, SS-RSRQ is defined as the ratio N × SS-RSRP / NR carrier RSSI, where N is the number of resource blocks within the RSSI measurement band. The NR carrier RSSI can be said to reflect the radio condition of neighboring cells in the same frequency band as the serving cell. Therefore, SS-RSRQ can be said to be inversely proportional to the radio condition of neighboring cells via the NR carrier RSSI included in its denominator. On the other hand, SS-SINR is obtained by dividing the linear average of the power contribution (in watt) of the resource elements carrying the CSI reference signals of the serving cell by the linear average of the noise and interference power contribution (in watt) of the resource elements transmitting the CSI reference signals within the same frequency bandwidth. Therefore, SS-SINR can be said to be inversely proportional to the radio state of adjacent cells through the linear average of the noise and interference power contributions included in its denominator.

[0057] Figure 4 shows an example where the RRC layer 203 of UE1 performs the burring check described above. In step 401, RAN node 2 sends burring control information to UE1. This burring control information includes the threshold described above. RAN node 2 may include the burring control information in the broadcast information (e.g., SIB) broadcast within cell 21 so that UEs that are RRC_IDLE or RRC_INACTIVE can receive the burring control information. RAN node 2 may also send burring control information for each Public Land Mobile Network (PLMN) Identity broadcast within cell 21.

[0058] In step 402, the NAS layer 202 receives a data transmission request (in other words, a session establishment request) from the application layer 201. In step 403, in response to receiving the data transmission request, the NAS layer 202 passes an initial NAS message (i.e., a registration request message or a service request message) to the RRC layer 203. In step 404, in response to receiving the initial NAS message, the RRC layer 203 performs an access burring check as described with reference to Figure 3. This check uses the thresholds contained in the burring control information (step 401). The RRC layer 203 may further perform one or more other access burring checks.

[0059] The trigger for the access barring check on the RRC layer 203 is not limited to the example in Figure 4. For example, the RRC layer 203 may perform an access barring check (404) when the RRC layer 203 requests or triggers the resumption of an RRC connection.

[0060] Figure 5 shows an example where the MAC layer 206 of UE1 performs the burring check described above. Step 501 is the same as step 401 in Figure 4. That is, RAN node 2 sends burring control information to UE1. This burring control information includes the threshold described above. In step 502, RRC layer 203 passes the received burring control information (i.e., threshold) to MAC layer 206. In other words, RRC layer 203 configures MAC layer 206 using the received burring control information (i.e., threshold).

[0061] Steps 503 and 504 are the same as steps 402 and 403 in Figure 4. In step 505, in response to receiving the initial NAS message, RRC layer 203 requests or triggers MAC layer 206 to initiate a random access procedure to send an RRC message (i.e., an RRC Setup Request message or an RRC Resume Request message) for establishing or restarting an RRC connection. In step 506, in response to receiving the trigger for the random access procedure, MAC layer 206 performs an access burring check as described with reference to Figure 3. This check uses the thresholds contained in the burring control information (step 501).

[0062] The triggers for the access burring check on MAC layer 206 are not limited to the example in Figure 5. For example, MAC layer 206 may receive a trigger for a random access procedure from RRC layer 203 based on other events, such as the re-establishment of an RRC connection, and may perform an access burring check in response to the receipt of this trigger. MAC layer 206 may also perform an access burring check (step 404) when a random access procedure is initiated by MAC layer 206 itself or by a Physical Downlink Control Channel (PDCCH) order.

[0063] According to the access barring or regulation described with reference to Figures 3 to 5, UE1 considers both the radio state of the serving cell and the radio state of adjacent cells operating in the same frequency band as the serving cell in order to determine whether access to the serving cell is permitted. For example, if the radio state of the serving cell is lower than a threshold compared to the radio state of adjacent cells in the same frequency band, UE1 may determine that access to the serving cell is prohibited. This operation prevents UE1 from accessing the serving cell if UE1 is located at the cell boundary between a serving cell and adjacent cells using the same frequency band. This prevents uplink transmissions to the serving cell by UE1 (e.g., RedCap UE) from interfering with uplink transmissions to adjacent cells by other UEs (e.g., legacy UEs).

[0064] <Second Embodiment> This embodiment provides another example of access barring checks performed by UE1. The configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Figure 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Figure 2.

[0065] Figure 6 shows an example of the access barring check operation performed by AS layer 208 of UE1. Here, UE1 is camped on to cell 21. In other words, cell 21 is the serving cell for UE1.

[0066] In some implementations, the RRC layer 203 may perform the access barring check. In this case, the RRC layer 203 may perform the access barring check in response to the start of an RRC connection establishment procedure or an RRC connection resumption procedure to a serving cell. The RRC layer 203 may perform the access barring check when an upper layer (i.e., the NAS layer) requests or triggers the establishment of an RRC connection. The RRC layer 203 may perform the access barring check when an upper layer (i.e., the NAS layer) or the RRC layer 203 requests or triggers the resumption of an RRC connection. In other implementations, the MAC layer 206 may perform the access barring check. In this case, the MAC layer 206 may perform the access barring check in response to the start of a random access procedure to a serving cell. The MAC layer 206 may perform the access barring check when it is triggered to start a random access procedure.

[0067] In step 601, UE1 determines whether access to the serving cell is prohibited by comparing the serving cell's current radio state with its past radio state. The serving cell's radio state may be rephrased as, for example, the serving cell's radio quality, channel state, channel quality, downlink signal state, or downlink signal quality. Prohibiting access to the serving cell means that establishing or re-establishing an RRC connection to the serving cell is prohibited. Alternatively, prohibiting access to the serving cell means that random access to the serving cell is prohibited.

[0068] If access to the serving cell is denied, UE1 terminates the procedure (step 602). In implementations where access barring checks are performed at the RRC layer 203, the terminated procedure may be an RRC connection establishment procedure or an RRC connection restart procedure. If the RRC layer 203 determines that access to the serving cell is denied, it may notify the higher layer (i.e., the NAS layer) of the failure to establish or restart the RRC connection. On the other hand, in implementations where access barring checks are performed at the MAC layer 206, the terminated procedure may be a random access procedure.

[0069] For example, UE1 may compare the current value of a metric, which increases in response to improvements in the serving cell's wireless condition, to a baseline value based on the metric's historical values. More specifically, UE1 may determine that access to the serving cell is permitted if the difference between the baseline value and the current value of the metric is less than a threshold. In other words, UE1 may determine that access to the serving cell is prohibited if the difference between the baseline value and the current value of the metric exceeds a threshold. The threshold may be a positive value.

[0070] The baseline value based on the historical value of the metric may be the maximum value (best value) of the metric within the most recent predetermined period. UE1 may set the baseline value to the current value if the current value of the metric is greater than the baseline value, or if the value obtained by subtracting the current value from the baseline value exceeds the threshold for a predetermined period. In other words, the baseline value of a metric may be replaced by the current value of the metric. That is, if the current wireless state of a serving cell is lower than the best wireless state of the serving cell in the past (or within the most recent predetermined period) by a threshold, UE1 may determine that access to the serving cell is prohibited.

[0071] UE1 may receive the information element indicating the threshold from the serving cell (e.g., cell 21) via broadcast. The RAN node providing the serving cell (e.g., RAN node 2) may broadcast the information element into cell 21 via system information (e.g., SIB2). The information element may indicate an index for UE1 to derive the threshold.

[0072] The metrics described above may also relate to the received signal power or received signal quality of the serving cell's downlink signal. These metrics may include, or be derived from, RSRP, RSRQ, or SINR measured by UE1. More specifically, these metrics may be, or be derived from, SS-RSRP, SS-RSRQ, or SS-SINR.

[0073] The metric may be a parameter derived or calculated from the measured RSRP or RSRQ. The metric may be the serving cell's Srxlev. Alternatively, the metric may be the serving cell's Squal. Srxlev is the cell selection RX level value (dB). Squal is the cell selection quality value (dB). Srxlev and Squal are also parameters used in the Cell Selection Criterion (i.e., S-criterion). Srxlev is the measured RSRP value (Q) of the serving cell. rxlevmeas Squal is calculated using the measured RSRQ value (Q) of the serving cell. qualmeas It is calculated using ).

[0074] In the case where the metric in question is the Srxlev of the serving cell, the threshold described above is the threshold parameter (S) defined for relaxed measurement criterion for UE with low mobility. SearchDeltaP) may be common with the threshold parameter (S) defined for relaxed measurement criterion for UE with low mobility. SearchDeltaP ) may be reused as the threshold for the burring check as described with reference to Figure 6. Furthermore, the predetermined period described above is the period parameter T defined for relaxed measurement criterion for UE with low mobility. SearchDeltaP It may also be common to the same parameters. By reusing parameters for relaxed measurement for access barring checks, the size of data transmitted or broadcast by RAN node 2 can be reduced. Relaxed measurement is also called relaxed monitoring for cell reselection. Relaxed measurement allows UEs (e.g., IoT devices) to reduce the monitoring time of adjacent cells, thereby contributing to reduced power consumption of these batteries.

[0075] According to the access barring or regulation described with reference to Figure 6, UE1 considers the current and past radio state of the serving cell to determine whether access to the serving cell is permitted. For example, if the current radio state of the serving cell is significantly lower than its past radio state by a threshold, UE1 may determine that access to the serving cell is prohibited. If the difference between the current and past radio states of the serving cell measured by UE1 is small, it is likely that UE1 is low-mobility or stationary. Therefore, this operation allows UE1 to access the serving cell when it is low-mobility or stationary. This provides access barring primarily to permit cell access by low-mobility UEs. The access barring or regulation described with reference to Figure 6 can provide a solution to the challenge of how to provide access barring primarily to permit cell access by low-mobility UEs.

[0076] For example, there may be a scenario where a particular cell primarily provides services to RedCap UEs with specific usage patterns. For instance, a particular cell within a factory premises might primarily provide services to stationary RedCap UEs (e.g., wireless sensors). Another scenario is where a stadium primarily provides services to RedCap UEs used for video surveillance. A RedCap UE used for video surveillance may store captured data while it is moving and upload the stored data when it is stationary and has good wireless connectivity. The access barring or restrictions described in this embodiment are effective in these scenarios, for example.

[0077] <Third Embodiment> This embodiment provides another example of access barring checks performed by UE1. The configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Figure 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Figure 2.

[0078] Figure 7 shows an example of UE1's operation. Here, cell 21 is the cell to which UE1 is currently camped, and therefore the serving cell for UE1.

[0079] In step 701, UE1 is S SearchThresholdP and S SearchThresholdQ One or more information elements indicating one or both of the above are received from cell 21 via broadcast. For example, such information elements may be included in SIB1 or SIB2. SearchThresholdP and S SearchThresholdQ This is used for the relaxed measurement criterion for UEs (e.g., IoT devices) not at the cell edge. Relaxed measurement is also called relaxed monitoring for cell reselection. Relaxed measurement allows UEs to reduce the monitoring time of adjacent cells, thereby contributing to reduced power consumption of these batteries.

[0080] In step 702, UE1 is using cell 21 as a serving cell, S SearchThresholdP Use this to determine whether to perform adjacent cell measurement for cell reselection. Furthermore, S SearchThresholdQ If this is set, UE1 will determine whether to perform an adjacent cell measurement for cell reselection when UE1 is using cell 21 as a serving cell, S SearchThresholdQ It is also used.

[0081] Specifically, S SearchThresholdP This is the threshold compared to Srxlev. On the other hand, S SearchThresholdQSrxlev is the threshold value compared to Squal. Srxlev is the cell selection reception (RX) level value (dB). Squal is the cell selection quality value (dB). Srxlev and Squal are also parameters used in the Cell Selection Criterion (i.e., S-criterion). Srxlev is the measured RSRP value (Q) of the serving cell. rxlevmeas Squal is calculated using the measured RSRQ value (Q) of the serving cell. qualmeas It is calculated using ). For example, if Srxlev is S SearchThresholdP If the value is larger and other specified conditions are also met, UE1 may choose not to perform adjacent cell measurements. Alternatively, if Srxlev is S SearchThresholdP If the measurement is larger and other specified conditions are met, UE1 may choose to perform relaxed measurements.

[0082] In step 703, UE1 performs an access barring check. UE1 also performs an S check to determine whether access to the serving cell is barred when UE1 is using cell 21 as the serving cell. SearchThresholdP and S SearchThresholdQ Use one or both of the following. UE1 is S SearchThresholdP and S SearchThresholdQ Use one or both of the following to determine whether UE1's access to the serving cell is barred. For example, if Srxlev is S SearchThresholdP If it is greater than S, it may be determined that access to the serving cell is permitted. Alternatively, UE1 may determine that Srxlev is S SearchThresholdP Larger and Squal is S SearchThresholdQ If it is greater than this, you may determine that access to the serving cell is permitted.

[0083] In some implementations, the RRC layer 203 may perform the access barring check. In this case, the RRC layer 203 may perform the access barring check in response to the start of an RRC connection establishment procedure or an RRC connection resumption procedure to a serving cell. The RRC layer 203 may perform the access barring check when an upper layer (i.e., the NAS layer) requests or triggers the establishment of an RRC connection. The RRC layer 203 may perform the access barring check when an upper layer (i.e., the NAS layer) or the RRC layer 203 requests or triggers the resumption of an RRC connection. In other implementations, the MAC layer 206 may perform the access barring check. In this case, the MAC layer 206 may perform the access barring check in response to the start of a random access procedure to a serving cell. The MAC layer 206 may perform the access barring check when it is triggered to start a random access procedure.

[0084] According to the operation described with reference to Figure 7, UE1 is the threshold parameter S for relaxed monitoring for cell reselection. SearchThresholdP and S SearchThresholdQ One or both of these parameters are reused for access burring checks. By reusing the parameters for relaxed measurement for access burring checks, the size of the data transmitted or broadcast by RAN node 2 can be reduced. In other words, the operation of UE1, as described with reference to Figure 7, can provide a solution to the challenge of how to suppress the increase in the size of the data transmitted or broadcast by RAN node 2 when new access burring is introduced.

[0085] <Fourth Embodiment> This embodiment provides another example of access barring checks performed by UE1. The configuration example of the wireless communication system according to this embodiment may be the same as the example shown in Figure 1. The protocol stack of the control plane of UE1 may be the same as the example shown in Figure 2.

[0086] Figure 8 shows an example of the access barring check operation performed by AS layer 208 of UE1. Here, UE1 is camped on to cell 21. In other words, cell 21 is the serving cell for UE1.

[0087] In some implementations, the RRC layer 203 may perform the access barring check. In this case, the RRC layer 203 may perform the access barring check in response to the start of an RRC connection establishment procedure or an RRC connection resumption procedure to a serving cell. The RRC layer 203 may perform the access barring check when an upper layer (i.e., the NAS layer) requests or triggers the establishment of an RRC connection. The RRC layer 203 may perform the access barring check when an upper layer (i.e., the NAS layer) or the RRC layer 203 requests or triggers the resumption of an RRC connection. In other implementations, the MAC layer 206 may perform the access barring check. In this case, the MAC layer 206 may perform the access barring check in response to the start of a random access procedure to a serving cell. The MAC layer 206 may perform the access barring check when it is triggered to start a random access procedure.

[0088] In step 801, UE1 determines whether or not to prohibit access to the serving cell based on the amount of data stored in UE1's uplink buffer. The uplink buffer stores the uplink data to be transmitted. The uplink buffer may be managed by the PDCP layer, RLC layer, or MAC layer. Specifically, UE1 may determine that access to the serving cell is permitted if the amount of data stored in the uplink buffer exceeds a threshold. In other words, UE1 may determine that access to the serving cell is prohibited if the amount of data stored in the uplink buffer falls below a threshold. Prohibiting access to the serving cell means that the establishment or reopening of an RRC connection to the serving cell is prohibited. Alternatively, prohibiting access to the serving cell means that random access to the serving cell is prohibited.

[0089] UE1 may receive the information element indicating the threshold from the serving cell (e.g., cell 21) via broadcast. The RAN node providing the serving cell (e.g., RAN node 2) may broadcast the information element into cell 21 via system information (e.g., SIB2). The information element may indicate an index for UE1 to derive the threshold.

[0090] If access to the serving cell is denied, UE1 terminates the procedure (step 802). In implementations where burring checks are performed at the RRC layer 203, the terminated procedure may be an RRC connection establishment procedure or an RRC connection restart procedure. If the RRC layer 203 determines that access to the serving cell is denied, it may notify the higher layer (i.e., the NAS layer) of the failure to establish or restart the RRC connection. On the other hand, in implementations where burring checks are performed at the MAC layer 206, the terminated procedure may be a random access procedure.

[0091] According to the access burring or regulation described with reference to Figure 8, UE1 can suppress frequent uplink transmissions of small data. This can contribute to improving the wireless utilization efficiency of cell 21. In other words, the access burring or regulation described with reference to Figure 8 can provide a solution to the challenge of how to suppress frequent uplink transmissions of small data. Furthermore, the access burring or regulation described with reference to Figure 8 can provide access burring suitable for UEs that primarily transmit uplink data. In other words, the access burring or regulation described with reference to Figure 8 can provide a solution to the challenge of how to provide access burring suitable for UEs that primarily transmit uplink data.

[0092] Next, configuration examples of UE1 and RAN node 2 according to the above-described multiple embodiments will be explained. Figure 9 is a block diagram showing a configuration example of UE1. The Radio Frequency (RF) transceiver 901 performs analog RF signal processing to communicate with the RAN node. The RF transceiver 901 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 901 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 901 is coupled with the antenna array 902 and the baseband processor 903. The RF transceiver 901 receives modulation symbol data (or OFDM symbol data) from the baseband processor 903, generates a transmit RF signal, and supplies the transmit RF signal to the antenna array 902. The RF transceiver 901 also generates a baseband receive signal based on the received RF signal received by the antenna array 902 and supplies it to the baseband processor 903. The RF transceiver 901 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, multiple phase shifters and multiple power amplifiers.

[0093] The baseband processor 903 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) generation / decomposition of transmission format (transmission frame), (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) by Inverse Fast Fourier Transform (IFFT). Control plane processing, on the other hand, includes communication management at Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attach, mobility, and call management).

[0094] For example, the digital baseband signal processing by the baseband processor 903 may include signal processing for the Service Data Adaptation Protocol (SDAP) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and Physical (PHY) layer. Furthermore, the control plane processing by the baseband processor 903 may include processing for the Non-Access Stratum (NAS) protocol, Radio Resource Control (RRC) protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs).

[0095] The baseband processor 903 may perform Multiple Input Multiple Output (MIMO) encoding and precoding for beamforming.

[0096] The baseband processor 903 may include a modem processor (e.g., Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 904 described later.

[0097] The application processor 904 is also called a CPU, MPU, microprocessor, or processor core. The application processor 904 may include multiple processors (multiple processor cores). The application processor 904 implements various functions of the UE1 by executing system software programs (Operating System (OS)) and various application programs (e.g., calling applications, web browsers, mail clients, camera operation applications, music playback applications) read from memory 906 or memory not shown.

[0098] In some implementations, the baseband processor 903 and the application processor 904 may be integrated on a single chip, as shown by the dashed line (905) in Figure 9. In other words, the baseband processor 903 and the application processor 904 may be implemented as a single System on Chip (SoC) device 905. An SoC device is sometimes called a System Large Scale Integration (LSI) or chipset.

[0099] Memory 906 is volatile memory, non-volatile memory, or a combination thereof. Memory 906 may include multiple physically independent memory devices. Volatile memory is, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory is Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or hard disk drive, or any combination thereof. For example, memory 906 may include an external memory device accessible from the baseband processor 903, the application processor 904, and the SoC 905. Memory 906 may also include an internal memory device integrated within the baseband processor 903, the application processor 904, or the SoC 905. Furthermore, memory 906 may include memory within a Universal Integrated Circuit Card (UICC).

[0100] The memory 906 may store one or more software modules (computer programs) 907 containing instruction sets and data for performing the processing by the UE1 as described in the above-described embodiments. In some implementations, the baseband processor 903 or application processor 904 may be configured to read and execute the software modules 907 from the memory 906 to perform the processing of the UE1 as described in the above embodiments with reference to the drawings.

[0101] Furthermore, the control plane processing and operation performed by the UE1 described in the above embodiment can be realized by other elements other than the RF transceiver 901 and antenna array 902, namely at least one of the baseband processor 903 and application processor 904 and the memory 906 storing the software module 907.

[0102] Figure 10 is a block diagram showing an example configuration of RAN node 2 according to the embodiment described above. Referring to Figure 10, RAN node 2 includes a Radio Frequency transceiver 1001, a network interface 1003, a processor 1004, and a memory 1005. The RF transceiver 1001 performs analog RF signal processing to communicate with UEs, including UE1. The RF transceiver 1001 may include multiple transceivers. The RF transceiver 1001 is coupled with an antenna array 1002 and a processor 1004. The RF transceiver 1001 receives modulation symbol data from the processor 1004, generates a transmit RF signal, and supplies the transmit RF signal to the antenna array 1002. The RF transceiver 1001 also generates a baseband receive signal based on the received RF signal received by the antenna array 1002 and supplies it to the processor 1004. The RF transceiver 1001 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, multiple phase shifters and multiple power amplifiers.

[0103] The network interface 1003 is used to communicate with network nodes (e.g., SN2, as well as control and forwarding nodes of the core network). The network interface 1003 may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0104] Processor 1004 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. Processor 1004 may include multiple processors. For example, processor 1004 may include a modem processor (e.g., Digital Signal Processor (DSP)) for digital baseband signal processing and a protocol stack processor (e.g., Central Processing Unit (CPU) or Micro Processing Unit (MPU)) for control plane processing. Processor 1004 may also include a digital beamformer module for beamforming. The digital beamformer module may include a Multiple Input Multiple Output (MIMO) encoder and precoder.

[0105] Memory 1005 is comprised of a combination of volatile and non-volatile memory. Volatile memory may be, for example, Static Random Access Memory (SRAM) or Dynamic RAM (DRAM), or a combination thereof. Non-volatile memory may be Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. Memory 1005 may also include storage located away from the processor 1004. In this case, the processor 1004 may access memory 1005 via the network interface 1003 or an I / O interface not shown.

[0106] The memory 1005 may store one or more software modules (computer programs) 1006 containing instruction sets and data for processing by the RAN node 2 as described in the above embodiments. In some implementations, the processor 1004 may be configured to read the software modules 1006 from the memory 1005 and execute them to perform the processing of the RAN node 2 as described in the above embodiments.

[0107] Furthermore, if RAN node 2 is a CU (e.g., gNB-CU) or CU-CP (e.g., gNB-CU-CP), RAN node 2 does not need to include the RF transceiver 1001 (and antenna array 1002).

[0108] As illustrated with reference to Figures 9 and 10, each of the processors in the UE1 and RAN node 2 according to the above embodiment can execute one or more programs, each containing a set of instructions for causing a computer to perform the algorithms described with reference to the drawings. The program, when loaded into a computer, contains a set of instructions (or software code) for causing the computer to perform one or more functions described in the embodiment. The program may be stored on a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD), or other memory technologies, CD-ROM, digital versatile disk (DVD), Blu-ray® disc, or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium containing electrical, optical, acoustic, or other forms of propagating signals.

[0109] The embodiments described above are merely examples of how the technical concept obtained by the present inventor can be applied. In other words, the technical concept is not limited to the embodiments described above, and various modifications are certainly possible.

[0110] For example, some or all of the above embodiments may also be described as follows, but are not limited to the following.

[0111] (Note 1) A wireless terminal, At least one memory, At least one processor coupled to the at least one memory, Equipped with, The at least one processor is configured to determine whether or not access to the serving cell by the wireless terminal is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. Wireless terminal. (Note 2) The at least one processor is configured to compare a first metric, which increases in response to an improvement in the radio state of the serving cell, with a second metric, which increases in response to an improvement in the radio state of the adjacent cell. The wireless terminal described in Appendix 1. (Note 3) The at least one processor is configured to determine that access to the serving cell is permitted if the value obtained by subtracting the first metric from the second metric is less than a threshold. The wireless terminal described in Appendix 2. (Note 4) The aforementioned threshold is a positive value. The wireless terminal described in Appendix 3. (Note 5) The at least one processor is configured to receive the threshold information element from the serving cell via broadcast. Wireless terminal as described in Appendix 3 or 4. (Note 6) The first metric relates to the received signal power or received signal quality of the downlink signal of the serving cell, The second metric relates to the received signal power or received signal quality of the downlink signal of the adjacent cell. A wireless terminal as described in any one of the items 2 to 5 of the appendix. (Note 7) Each of the first and second metrics includes or is derived from Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or signal-to-interference-plus-noise power ratio (SINR). A wireless terminal as described in any one of the items in Appendix 2 to 6. (Note 8) The at least one processor is configured to determine that access to the serving cell is permitted if a third metric, which increases in response to an improvement in the wireless state of the serving cell and decreases in response to an improvement in the wireless state of the adjacent cell, is greater than a threshold. The wireless terminal described in Appendix 1. (Note 9) The third metric includes or is derived from the Reference Signal Received Quality (RSRQ) or signal-to-interference-plus-noise power ratio (SINR) of the downlink signal of the serving cell. The wireless terminal described in Appendix 8. (Note 10) The at least one processor is configured to provide Radio Resource Control (RRC) layer functionality, The RRC layer function is configured to perform the determination. A wireless terminal as described in any one of the items 1 to 9 in the appendix. (Note 11) The RRC layer function is configured to perform the determination when a higher layer requests the establishment or resumption of an RRC connection. The wireless terminal described in Appendix 10. (Note 12) The aforementioned at least one processor is configured to provide Medium Access Control (MAC) layer functionality, The MAC layer function is configured to perform the determination. A wireless terminal as described in any one of the items 1 to 9 in the appendix. (Note 13) The MAC layer function is configured to perform the determination when the MAC layer function is triggered to initiate a random access procedure. The wireless terminal described in Appendix 12. (Note 14) The MAC layer function is configured to perform the determination when initiating a random access procedure. Wireless terminal as described in Appendix 12 or 13. (Note 15) A method performed by a wireless terminal, The system includes determining whether access to the serving cell by the wireless terminal is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. method. (Note 16) A program for causing a computer to perform a method for wireless terminals, The method comprises determining whether or not access to the serving cell by the wireless terminal is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. program. (Note 17) At least one memory, At least one processor coupled to the at least one memory, Equipped with, The at least one processor is configured to broadcast an information element indicating a threshold in a first cell, The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. Wireless access network node. (Note 18) The wireless terminal is configured to compare a first metric, which increases in response to an improvement in the wireless state of the serving cell, with a second metric, which increases in response to an improvement in the wireless state of the adjacent cell. The wireless access network node described in Appendix 17. (Note 19) The wireless terminal is configured to determine that access to the serving cell is permitted if the value obtained by subtracting the first metric from the second metric is less than the threshold. The wireless access network node described in Appendix 18. (Note 20) The aforementioned threshold is a positive value. The wireless access network node described in Appendix 19. (Note 21) The system includes broadcasting an information element indicating a threshold in the first cell, The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. A method performed by a wireless access network node. (Note 22) A program for causing a computer to perform a method for a wireless access network node, The method comprises broadcasting an information element indicating a threshold in a first cell, The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. program. (Note 23) A wireless terminal, At least one memory, At least one processor coupled to the at least one memory, Equipped with, The at least one processor is configured to determine whether or not access to the serving cell by the wireless terminal is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell. Wireless terminal. (Note 24) The at least one processor is configured to compare the current value of a metric, which increases in response to an improvement in the wireless state of the serving cell, with a reference value based on the historical value of the metric. The wireless terminal described in Appendix 23. (Note 25) The at least one processor is configured to determine that access to the serving cell is permitted if the value obtained by subtracting the current value from the reference value is less than a threshold. The wireless terminal described in Appendix 24. (Note 26) The aforementioned threshold is a positive value. The wireless terminal described in Appendix 25. (Note 27) The at least one processor is configured to set the reference value to the current value if the current value is greater than the reference value, or if the value obtained by subtracting the current value from the reference value exceeds the threshold for a predetermined period of time. Wireless terminals as described in Appendix 25 or 26. (Note 28) The at least one processor is configured to receive the threshold information element from the serving cell via broadcast. A wireless terminal as described in any one of the items 25 to 27 of the appendix. (Note 29) The metric relates to the received signal power or received signal quality of the downlink signal of the serving cell. A wireless terminal as described in any one of the items 24 to 28 of the appendix. (Note 30) The aforementioned metrics include or are derived from Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or signal-to-interference-plus-noise power ratio (SINR). A wireless terminal as described in any one of the items 24 to 29 of the appendix. (Note 31) The at least one processor is configured to provide Radio Resource Control (RRC) layer functionality, The RRC layer function is configured to perform the determination. A wireless terminal as described in any one of the items in Appendix 23 to 30. (Note 32) The RRC layer function is configured to perform the determination when a higher layer requests the establishment or resumption of an RRC connection. The wireless terminal described in Appendix 31. (Note 33) The aforementioned at least one processor is configured to provide Medium Access Control (MAC) layer functionality, The MAC layer function is configured to perform the determination. A wireless terminal as described in any one of the items in Appendix 23 to 30. (Note 34) The MAC layer function is configured to perform the determination when the MAC layer function is triggered to initiate a random access procedure. The wireless terminal described in Appendix 33. (Note 35) The MAC layer function is configured to perform the determination when initiating a random access procedure. Wireless terminal as described in Appendix 33 or 34. (Note 36) A method performed by a wireless terminal, The system includes determining whether access to the serving cell by a wireless terminal is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell. method. (Note 37) A program for causing a computer to perform a method for wireless terminals, The method comprises determining whether or not access to the serving cell by the wireless terminal is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell. program. (Note 38) At least one memory, At least one processor coupled to the at least one memory, Equipped with, The at least one processor is configured to broadcast an information element indicating a threshold in a first cell, The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell by the wireless terminal is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell. Wireless access network node. (Note 39) The wireless terminal is configured to compare the current value of a metric, which increases in accordance with the improvement of the wireless state of the serving cell, with a reference value based on the historical value of the metric. The wireless access network node described in Appendix 38. (Note 40) The wireless terminal is configured to determine that access to the serving cell is permitted if the value obtained by subtracting the current value from the reference value is less than the threshold value. The wireless access network node described in Appendix 39. (Note 41) The aforementioned threshold is a positive value. The wireless access network node described in Appendix 40. (Note 42) The system includes broadcasting an information element indicating a threshold in the first cell, The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell by the wireless terminal is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell. A method performed by a wireless access network node. (Note 43) A program for causing a computer to perform a method for a wireless access network node, The method comprises broadcasting an information element indicating a threshold in a first cell, The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell by the wireless terminal is barred by comparing the current wireless state of the serving cell with the past wireless state of the serving cell. program. (Note 44) A wireless terminal, At least one memory, At least one processor coupled to the at least one memory, Equipped with, The aforementioned at least one processor is S SearchThresholdP and S SearchThresholdQ It is configured to receive one or more information elements indicating one or both of the above from a first cell via broadcast, The aforementioned S SearchThresholdP This is a threshold value compared with the cell selection RX level value (Srxlev) of the serving cell in order to determine whether the wireless terminal performs adjacent cell measurement for cell reselection when the wireless terminal is using the first cell as a serving cell. The aforementioned S SearchThresholdQ This is a threshold value compared to the cell selection quality value (Squal) of the serving cell in order to determine whether the wireless terminal performs the adjacent cell measurement for cell reselection when the wireless terminal is using the first cell as the serving cell. The at least one processor also determines whether access by the wireless terminal to the serving cell is barred when the wireless terminal is using the first cell as the serving cell. SearchThresholdP and the aforementioned S SearchThresholdQ Configured to use one or both of the following: Wireless terminal. (Note 45) The at least one processor is such that the Srxlev is the S SearchThresholdP If it is greater than, it is configured to determine that access to the serving cell is permitted. The wireless terminal described in Appendix 44. (Note 46) The at least one processor is such that the Srxlev is the S SearchThresholdP Larger and the Squal is SearchThresholdQ If it is greater than, it is configured to determine that access to the serving cell is permitted. The wireless terminal described in Appendix 44. (Note 47) The at least one processor is configured to provide Radio Resource Control (RRC) layer functionality, The RRC layer function is configured to make the determination of whether or not access to the serving cell by the wireless terminal is prohibited (barred). A wireless terminal as described in any one of the items in Appendix 44 to 46. (Note 48) The aforementioned at least one processor is configured to provide Medium Access Control (MAC) layer functionality, The MAC layer function is configured to make the determination of whether or not the wireless terminal's access to the serving cell is prohibited (barred). A wireless terminal as described in any one of the items in Appendix 44 to 46. (Note 49) The MAC layer function is configured to make the determination of whether or not access to the serving cell by the wireless terminal is barred when the MAC layer function is triggered to initiate a random access procedure. The wireless terminal described in Appendix 48. (Note 50) A method performed by a wireless terminal, S SearchThresholdP and S SearchThresholdQ Receiving one or more information elements from the first cell via broadcast that indicate one or both of the above, Here, the S SearchThresholdPThis is a threshold value compared with the cell selection RX level value (Srxlev) of the serving cell in order to determine whether the wireless terminal performs adjacent cell measurement for cell reselection when the wireless terminal is using the first cell as a serving cell. The aforementioned S SearchThresholdQ This is a threshold value compared to the cell selection quality value (Squal) of the serving cell in order to determine whether the wireless terminal performs the adjacent cell measurement for cell reselection when the wireless terminal is using the first cell as the serving cell; and When the wireless terminal is using the first cell as the serving cell, the S is used to determine whether or not access to the serving cell by the wireless terminal is barred. SearchThresholdP and the aforementioned S SearchThresholdQ To use one or both of the following: A method for providing this. (Note 51) A program for causing a computer to perform a method for wireless terminals, The aforementioned method, S SearchThresholdP and S SearchThresholdQ Receiving one or more information elements from the first cell via broadcast that indicate one or both of the above, Here, the S SearchThresholdP This is a threshold value compared with the cell selection RX level value (Srxlev) of the serving cell in order to determine whether the wireless terminal performs adjacent cell measurement for cell reselection when the wireless terminal is using the first cell as a serving cell. The aforementioned S SearchThresholdQ This is a threshold value compared to the cell selection quality value (Squal) of the serving cell in order to determine whether the wireless terminal performs the adjacent cell measurement for cell reselection when the wireless terminal is using the first cell as the serving cell; and When the wireless terminal is using the first cell as the serving cell, the S is used to determine whether or not access to the serving cell by the wireless terminal is barred. SearchThresholdP and the aforementioned S SearchThresholdQ To use one or both of the following: A program that includes the following features. (Note 52) A wireless terminal, At least one memory, At least one processor coupled to the at least one memory, Equipped with, The at least one processor is configured to determine whether or not the wireless terminal's access to the serving cell is barred, based on the amount of data stored in the wireless terminal's uplink buffer. Wireless terminal. (Note 53) The at least one processor is configured to determine that access to the serving cell is permitted if the amount of data is greater than a threshold. The wireless terminal described in Appendix 52. (Note 54) The at least one processor is configured to receive the threshold information element from the serving cell via broadcast. The wireless terminal described in Appendix 53. (Note 55) The at least one processor is configured to provide Radio Resource Control (RRC) layer functionality, The RRC layer function is configured to perform the determination. A wireless terminal as described in any one of the items 52 to 54 of the appendix. (Note 56) The RRC layer function is configured to perform the determination when a higher layer requests the establishment or resumption of an RRC connection. The wireless terminal described in Appendix 55. (Note 57) The aforementioned at least one processor is configured to provide Medium Access Control (MAC) layer functionality, The MAC layer function is configured to perform the determination. A wireless terminal as described in any one of the items 52 to 54 of the appendix. (Note 58) The MAC layer function is configured to perform the determination when the MAC layer function is triggered to initiate a random access procedure. The wireless terminal described in Appendix 57. (Note 59) A method performed by a wireless terminal, The system includes determining whether or not access to the serving cell by the wireless terminal is barred, based on the amount of data stored in the uplink buffer of the wireless terminal. method. (Note 60) A program for causing a computer to perform a method for wireless terminals, The method comprises determining whether or not access to the serving cell by the wireless terminal is barred, based on the amount of data stored in the uplink buffer of the wireless terminal. program. (Note 61) At least one memory, At least one processor coupled to the at least one memory, Equipped with, The at least one processor is configured to broadcast an information element indicating a threshold in a first cell, The threshold is used to determine whether access to the serving cell by a wireless terminal using the first cell as a serving cell is barred, based on the amount of data accumulated in the uplink buffer of the wireless terminal. Wireless access network node. (Note 62) The wireless terminal is configured to determine that access to the serving cell is permitted if the amount of data is greater than the threshold. The wireless access network node described in Appendix 61. (Note 63) The system includes broadcasting an information element indicating a threshold in the first cell, The threshold is used to determine whether access to the serving cell by a wireless terminal using the first cell as a serving cell is barred, based on the amount of data accumulated in the uplink buffer of the wireless terminal. A method performed by a wireless access network node. (Note 64) A program for causing a computer to perform a method for a wireless access network node, The method comprises broadcasting an information element indicating a threshold in a first cell, The threshold is used to determine whether access to the serving cell by a wireless terminal using the first cell as a serving cell is barred, based on the amount of data accumulated in the uplink buffer of the wireless terminal. program.

[0112] This application claims priority based on Japanese Patent Application No. 2021-168191, filed on 13 October 2021, and incorporates all of its disclosures herein. [Explanation of Symbols]

[0113] 1 UE 2, 3 RAN nodes 903 Baseband Processor 904 Application Processor 906 memory 907 Modules 1004 Processor 1005 memory 1006 modules

Claims

1. A wireless terminal, The system includes means for determining whether access to the serving cell by a wireless terminal is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. Wireless terminal.

2. The means for making the determination is configured to compare a first metric that increases in response to an improvement in the wireless state of the serving cell with a second metric that increases in response to an improvement in the wireless state of the adjacent cell. The wireless terminal according to claim 1.

3. The means for making the determination is configured to determine that access to the serving cell is permitted if the value obtained by subtracting the first metric from the second metric is less than a threshold. The wireless terminal according to claim 2.

4. The first metric relates to the received signal power or received signal quality of the downlink signal of the serving cell. The second metric relates to the received signal power or received signal quality of the downlink signal of the adjacent cell. The wireless terminal according to claim 2 or 3.

5. The means for making the determination is configured to determine that access to the serving cell is permitted if a third metric, which increases in accordance with the improvement of the wireless state of the serving cell and decreases in accordance with the improvement of the wireless state of the adjacent cell, is greater than a threshold. The wireless terminal according to claim 1.

6. Further comprising means for providing Radio Resource Control (RRC) layer functionality, The RRC layer function includes the means for making the determination. A wireless terminal according to any one of claims 1 to 3.

7. The determination means included in the RRC layer function is configured to perform the determination when a higher layer requests the establishment or resume of an RRC connection. The wireless terminal according to claim 6.

8. Further comprising means for providing Medium Access Control (MAC) layer functionality, The MAC layer function includes the means for making the determination. A wireless terminal according to any one of claims 1 to 3.

9. A method performed by a wireless terminal, The system includes determining whether access to the serving cell by the wireless terminal is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. method.

10. A means for broadcasting an information element indicating a threshold in a first cell, The threshold is used by a wireless terminal using the first cell as a serving cell to determine whether access to the serving cell by the wireless terminal is barred by comparing the wireless state of the serving cell with the wireless state of an adjacent cell in the same frequency band as the serving cell. Wireless access network node.

Images