Ambient IoT device, reader, and methods therefor

Abstract

This Ambient Internet of Things (AIoT) device is used to trigger or cause random access by one or more AIoT devices, and receives a reader to device (R2D) message that identifies one or both of a first-type random access procedure and a second-type random access procedure to be allowed. The AIoT device determines whether to perform the first-type random access procedure and / or the second-type random access procedure on the basis of the R2D message. The invention thus contributes to, for example, solving problems related to support of an AIoT device in a cellular network.

Description

Ambient IoT Devices, Readers, and Methods Thereof

[0001] The present disclosure relates to wireless communication systems in which Ambient Internet of Things (AIoT) devices are used.

[0002] The 3rd Generation Partnership Project (3GPP (registered trademark)) is considering supporting AIoT devices in 5G NR for Release 19 and beyond (see, for example, non-patent documents 1-5). AIoT devices are ambient power-enabled IoT devices. AIoT devices are IoT devices that are powered by energy harvesting and are battery-less or have limited energy storage capabilities (e.g., using capacitors). Energy for AIoT devices is supplied by harvesting radio waves, light, motion, heat, or other suitable power sources.

[0003] AIoT device types may be distinguished by the presence or absence of power storage capabilities. Additionally or alternatively, AIoT device types may be distinguished by the magnitude of their peak power consumption. Additionally or alternatively, AIoT device types may be distinguished by whether they have uplink amplification and / or downlink amplification. Additionally or alternatively, AIoT device types may be distinguished by whether the device's uplink transmission is a backscatter transmission on an externally supplied carrier or is generated by the device's active Radio Frequency (RF) components.

[0004] Non-Patent Document 2 discloses roughly four connectivity topologies for AIoT devices, as follows: Topology 1 is direct communication between a base station and an AIoT device. In Topology 1, the AIoT device communicates directly and bidirectionally with the base station. The communication between the base station and the AIoT device includes one or both of AIoT data and signaling. Topology 1 includes the possibility that the base station transmitting to the AIoT device and the base station receiving from the AIoT device may be different.

[0005] Topology 2 is communication between a base station and an AIoT device via an intermediate node. In Topology 2, the AIoT device communicates bidirectionally with the intermediate node located between the device and the base station. The intermediate node can be a relay, Integrated Access and Backhaul (IAB) node, User Equipment (UE), or repeater, which are compatible with Ambient IoT. The intermediate node transfers AIoT data and / or signaling between the base station and the AIoT device.

[0006] Topology 3 is communication between a base station and an AIoT device via an assisting node. Topology 3 includes an option where the assisting node assists the downlink (Topology 3 with downlink assistance) and an option where the assisting node assists the uplink (Topology 3 with uplink assistance). In Topology 3 with downlink assistance, the AIoT device transmits data and / or signaling to the base station and receives data and / or signaling from the assisting node. In Topology 3 with uplink assistance, the AIoT device receives data and / or signaling from the base station and transmits data and / or signaling to the assisting node. The assisting node is a relay, IAB node, UE, repeater, etc. that supports ambient IoT.

[0007] Topology 4 is direct communication between the UE and the AIoT device. In Topology 4, the AIoT device communicates bidirectionally with the UE. The communication between the UE and the AIoT device includes AIoT data and / or signaling.

[0008] Non-Patent Document 1 presents a study item on solutions for AIoT in NR. The overall objective of this study item is to consider a harmonized air interface design for AIoT with minimized differences (if necessary) to enable the following two types of devices: The first type of AIoT device has a peak power consumption of approximately 1 μW or less, has energy storage, and does not have downlink or uplink amplification within the device. The uplink transmission of the first type of AIoT device is backscattered on an externally supplied carrier. The second type of AIoT device has a power consumption of several hundred μW or less, has energy storage, and has one or both downlink and uplink amplification. The uplink transmission of the second type of AIoT device is backscattered transmission on an externally supplied carrier or is generated by active RF components within the device.

[0009] The general scope of the study item defined in Non-Patent Document 1 assumes no Radio Resource Control (RRC) state, no mobility (i.e., at least no cell selection / re-selection-like functions), no Hybrid Automatic Repeat Request (HARQ), and no ARQ. In addition, the general scope of the study item targets Topology 1 and Topology 2 among the connection topologies described in Non-Patent Document 2, and assumes a UE as an intermediate node in Topology 2.

[0010] Section 8.2 of Non-Patent Document 4 describes the discussions and agreements regarding Ambient IoT at the 126th meeting of the 3GPP Technical Specification Group (TSG) Radio Access Network (RAN) Working Group #2 (WG2) (RAN2). Section 8.2.2 of Non-Patent Document 4 describes the following agreements regarding Stage 2 general aspects, particularly regarding the three cases of "inventory only," "command only," and "inventory and command."

[0011] As a baseline, the "inventory only" case is supported by the following steps: Step A: AIoT Paging; and Step B: Device ID transmission (via random access (RA) or without RA). Details of Step B will be discussed further.

[0012] As a baseline, the "inventory and command" case is supported by the following steps: Step A: AIoT paging; Step B: Device ID transmission (via random access (RA) or without RA); Step C: Reader to device (R2D) data transmission (e.g., R2D command); and Step D: Supported device to reader (D2R) data transmission (e.g., feedback). Whether Step D is optional is left for discussion in other WGs.

[0013] "Inventory and command" does not mean that AIoT paging includes both inventory and command in the same message. "Inventory and command" does not mean that inventory and command are received by the reader from upper layers at the same time.

[0014] RAN2 considers a "command only" use case. Options to support this will be further explored. In the "command only" use case, the initial trigger message from the reader is expected to contain the command, but the ultimate feasibility of this will depend on the work and conclusions of 3GPP TSG Service and System Aspects (SA) WG #2 (SA2) and WG #3 (SA3). The "command only" use case will use the "inventory and command" baseline procedure (i.e., first trigger the inventory procedure, then send the command).

[0015] Section 8.2.3 of Non-Patent Document 4 states the following agreement regarding functionality aspects:

[0016] Multiple AIoT logical channels for upper layer data are not supported. Whether the concept of AIoT logical channels will be used is further discussed and depends on the final modeling issue.

[0017] Neither the legacy NR Buffer Status Report (BSR) nor the Scheduling Request (SR) are required for AIoT communication. Whether additional indications regarding the size or status of device messages (i.e., D2R messages) are needed will be discussed further.

[0018] Access Stratum (AS) Radio Link Control (RLC)-like retransmissions or repetitions (above the physical layer) are not supported. This does not preclude readers and AIoT devices from retransmitting the payload as a new transmission from a Medium Access Control (MAC) perspective. How to handle segmentation cases will be discussed further if necessary.

[0019] Section 8.2.4 of Non-Patent Document 4 describes the following agreements regarding AIoT paging:

[0020] RAN2 considers the following cases for AIoT paging messages: - A message containing the ID of a single AIoT device; - A message containing a group ID corresponding to multiple AIoT devices; - A message without an ID, i.e., a message targeted at all devices that can receive AIoT messages; - A message containing multiple IDs of multiple AIoT devices.

[0021] Based on the discussion in SA2, the need for use cases of messages containing multiple IDs of multiple AIoT devices needs to be confirmed. What the device IDs, group IDs, and scenarios are depends on the discussion in SA2.

[0022] The AIoT paging message indicates information that allows the device to decide which resources to use for the response (D2R message). How (e.g., implicit / explicit / configured / preconfigured) and what resources (dedicated and / or shared) are provided to the device will be further considered in light of the discussions in 3GPP TSG RAN WG #1 (WG1) (RAN1).

[0023] From the perspective of RAN2, it is assumed that AIoT devices will be able to receive as long as there is sufficient energy. For details on device monitoring, we will await future progress on RAN1.

[0024] Section 8.2.5 of Non-Patent Document 4 describes the following agreements regarding AIoT random access (RA):

[0025] The four-step RA agreement includes the following: In the first AIoT RA message (Msg1), the device sends its ID to the reader. This ID is a random ID generated by the device. How the ID is generated, for example, whether it is randomly generated or generated based on the device ID, is further discussed. This does not exclude other RAN1 agreed information. In the second AIoT RA message (Msg2), the reader echoes the ID received in Msg1. Based on the RAN1 agreement, further information may be included in Msg2. In the third AIoT RA message (Msg3), the device sends its device ID and / or other upper layer data (depending on the upper layer requirements). If the device receives Msg2 containing the same random ID as Msg1, it considers the conflict resolution successful. RAN2 assumes that the size of the random ID in Msg1 is sufficient for conflict resolution purposes. The "fourth message (Msg4)" (i.e., the subsequent R2D transmission after a D2R transmission) does not necessarily have to be transmitted in random access. Msg4 can be considered to handle the failure of Msg3 transmission (due to various reasons). The use and existence of Msg4 can be further discussed. In RAN2, the term "Msg4" is not used in further discussions of random access.

[0026] Agreement on a two-step RA includes the following: In AIoT RA Msg1, the device sends the device ID and / or other upper layer data (depending on the upper layer requirements). What the device ID is and whether an additional random ID is required will be confirmed in further discussion. This does not exclude other RAN1 agreed information. In AIoT RA Msg2, the reader may echo some information from Msg1. What that information is, as well as the use and existence of Msg2, can be further discussed.

[0027] Section 8.2 of Non-Patent Document 5 describes the discussions and agreements regarding Ambient IoT at the 125bis meeting of 3GPP RAN2. Section 8.2.5 of Non-Patent Document 5 describes the following agreements regarding AIoT RA: RAN2 confirmed that the baseline for AIoT random access is slotted ALOHA. RAN2 considers support for access triggers for a single device, a group of devices, or all devices. RAN2 considers contention-based and contention-free access procedures and detailed solutions. Random access is triggered by the leader.

[0028] As can be understood from the above-mentioned RAN2 agreement on AIoT RA, an AIoT 4-step RA may not use Msg4 and may therefore actually consist of three steps (i.e., Msg1, Msg2, and Msg3 transmissions). Similarly, an AIoT 2-step RA may not use Msg2 and may therefore actually consist of only one step (i.e., Msg1 transmission). Taking these factors into consideration, the terms "4-step-like random access (procedure)" and "2-step-like random access (procedure)" are used herein. The term "4-step-like random access (procedure)" refers to a first type of AIoT RA procedure that may not use Msg4 and may therefore actually consist of three steps (i.e., Msg1, Msg2, and Msg3 transmissions). In other words, the term "4-step-like random access (procedure)" may refer to a 3-step RA or a 4-step RA. The term "two-step-like random access" refers to a second type of AIoT RA procedure that may not use Msg2 and therefore may actually consist of only one step (i.e., Msg1 transmission). In other words, the term "two-step-like random access" may refer to a one-step RA or a two-step RA.

[0029] Huawei, "New SID: Study on solutions for Ambient IoT (Internet of Things) in NR", RP-234058, 3GPP TSG RAN Meeting #102, Edinburgh, UK, December 11-15, 20233GPP TR 38.848 V18.0.0 (2023-09) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on Ambient IoT (Internet of Things) in RAN (Release 18)", September 20233GPP TR 22.840 V19.0.0 (2023-12) "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Study on Ambient power-enabled Internet of Things (Release 19)", December 2023ETSI MCC, "Report of 3GPP TSG RAN WG2 meeting #126, Fukuoka, Japan", [online], [retrieved on 2024-7-28], Retrieved from the Internet: <URL: https: / / www.3gpp.org / ftp / TSG_RAN / WG2_RL2 / TSGR2_126 / Report / Draft_R2_126_Meeting_Report_v2.zip>ETSI MCC, "Report of 3GPP TSG RAN WG2 meeting #125bis, Changsha, China", R2-2404102, 3GPP TSG-RAN WG2 meeting #126, May 2024

[0030] The inventors have investigated communication between AIoT devices and a reader and found various issues. Here, the reader is a base station in the case of Topology 1, an intermediate node in the case of Topology 2, one or a combination of a base station and an assist node in the case of Topology 3, and a UE in the case of Topology 4.

[0031] One of these challenges relates to the selection of an RA procedure in AIoT access. First, when multiple RA procedures are supported, such as the above-mentioned four-step-like RA procedure and two-step-like RA procedure, it is not clear how to select one of the multiple RA procedures to be used.

[0032] Another issue concerns the use of the fourth message (Msg4) of the four-step-like RA procedure and the second message (Msg2) of the two-step-like RA procedure in AIoT access. As mentioned above, 3GPP RAN2 has agreed that Msg4 of the four-step-like RA procedure does not necessarily need to be transmitted. Similarly, 3GPP RAN2 has agreed that Msg2 of the two-step-like RA procedure does not necessarily need to be transmitted. It is unclear in what cases Msg4 of the four-step-like RA procedure and Msg2 of the two-step-like RA procedure are preferably used.

[0033] Yet another issue concerns the use of slotted ALOHA in AIoT access. As mentioned above, it has been agreed that slotted ALOHA is the baseline for AIoT random access. To address the packet collision problem in slotted ALOHA, Diversity Slotted ALOHA (DSA) and Contention Resolution Diversity Slotted ALOHA (CRDSA) are known. DSA improves throughput by using packet diversity transmission. CDRSA improves throughput by effectively combining packet diversity transmission and iterative interference cancellation. Using CRDSA can be effective in reducing the collision problem of multiple Msg1 transmissions by multiple AIoT devices in a two-step-like RA procedure. However, at present, it is unclear how to use DSA or CRDSA for multiple Msg1 transmissions by multiple AIoT devices in a two-step-like RA procedure.

[0034] One of the objectives of the embodiments disclosed herein is to provide an apparatus, a method, and a program that contribute to solving at least one of the problems related to communication between an AIoT device and a reader, including the problems described above. It should be noted that this objective is only one of the objectives of the embodiments disclosed herein. Other objectives or objectives and novel features will become apparent from the description of this specification or the accompanying drawings.

[0035] In a first aspect, an AIoT device is configured to receive an R2D message used to trigger or cause random access by one or more AIoT devices and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed, and the AIoT device is configured to determine whether to perform one or both of the first type of random access procedure and the second type of random access procedure based on the R2D message.

[0036] In a second aspect, a method performed by an AIoT device includes (a) receiving an R2D message used to trigger or cause random access by one or more AIoT devices and specifying one or both of a first type random access procedure and a second type random access procedure that are allowed, and (b) determining whether to perform one or both of the first type random access procedure and the second type random access procedure based on the R2D message.

[0037] In a third aspect, a reader is configured to transmit an R2D message used to trigger or cause random access by one or more AIoT devices and specifying one or both of a first type random access procedure and a second type random access procedure that are allowed, the R2D message causing the AIoT devices to decide whether to perform one or both of the first type random access procedure and the second type random access procedure.

[0038] In a fourth aspect, a method performed by a reader includes transmitting an R2D message used to trigger or cause random access by one or more AIoT devices and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed, the R2D message causing the AIoT devices to decide whether to perform one or both of the first type of random access procedure and the second type of random access procedure.

[0039] In a fifth aspect, an AIoT device is configured to receive an R2D message, autonomously determine whether to perform a first type random access procedure or a second type random access procedure, and communicate with a reader according to the determined random access procedure at one or more of a plurality of access occasions within a paging round initiated by the R2D message.

[0040] In a sixth aspect, a method performed by an AIoT device includes: (a) receiving an R2D message; (b) autonomously determining whether to perform a first type random access procedure or a second type random access procedure; and (b) communicating with a reader according to the determined random access procedure in one or more of a plurality of access occasions within a paging round initiated by the R2D message.

[0041] In a seventh aspect, the AIoT device is configured to, if a second trigger message is used in the inventory procedure, attempt to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, or attempt to receive a second message in a two-step-like random access procedure performed at the access occasion.

[0042] In an eighth aspect, a method performed by an AIoT device includes, if a second trigger message is used in an inventory procedure, attempting to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, or attempting to receive a second message in a two-step-like random access procedure performed at the access occasion.

[0043] In a ninth aspect, an AIoT device is configured to receive an R2D message specifying a first parameter for defining the number of access occasions in a paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure transmitted in the paging round. The AIoT device is configured to select access occasions equal to the number of replicas using the first parameter and the second parameter. The AIoT device is configured to attempt to transmit two or more replicas of the first message to a leader in the two or more selected access occasions.

[0044] In a tenth aspect, a method performed by an AIoT device includes: (a) receiving an R2D message specifying a first parameter for defining a number of access occasions in a paging round and a second parameter for defining a number of two or more replicas of a first message of a two-step-like random access procedure transmitted in the paging round; (b) using the first parameter and the second parameter to select access occasions equal in number to the number of replicas; and (c) attempting to transmit two or more replicas of the first message to a leader in the selected two or more access occasions.

[0045] In an eleventh aspect, a program includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform a method according to any of the above aspects.

[0046] According to the above-mentioned aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of multiple problems related to communication between an AIoT device and a reader, including the problems described above.

[0047]

[0014] Figure 1 illustrates an example of a connection topology for AIoT devices, which may be related to one or more embodiments.

[0015] Figure 2 illustrates an example of a connection topology for AIoT devices, which may be related to one or more embodiments.

[0016] Figure 3 illustrates an example of a connection topology for AIoT devices, which may be related to one or more embodiments.

[0017] Figure 4 illustrates an example of a connection topology for AIoT devices, which may be related to one or more embodiments.

[0018] Figure 5 illustrates an example of an inventory procedure, which may be related to one or more embodiments.

[0019] Figure 6 illustrates an example of an inventory and command procedure, which may be related to one or more embodiments.

[0020] Figure 7 illustrates an example of a command procedure, which may be related to one or more embodiments.

[0021] Figure 8 illustrates an example of a random access using slotted ALOHA, which may be related to one or more embodiments.

[0022] Figure 9 illustrates an example of an inventory procedure using slotted ALOHA, which may be related to one or more embodiments.

[0023] Figure 10 illustrates an example of an inventory procedure using slotted ALOHA, which may be related to one or more embodiments.

[0024] Figure 11 illustrates an example of an inventory procedure using slotted ALOHA, which may be related to one or more embodiments.

[0025] Figure 12 illustrates an example of an inventory procedure using slotted ALOHA, which may be related to one or more embodiments.

[0026] Figure 13 illustrates an example of an operation of an AIoT device and a reader, which may be related to one or more embodiments.

[0027] Figure 14 is a flowchart illustrating an example of an operation of an AIoT device, which may be related to one or more embodiments. FIG. 1 illustrates an example format of a first random access message (Msg1), which relates to one or more embodiments. FIG. 2 illustrates an example format of a first random access message (Msg1), which relates to one or more embodiments. FIG. 3 illustrates an example operation of an AIoT device and a reader, which relates to one or more embodiments. FIG. 4 is a flowchart illustrating an example operation of an AIoT device, which relates to one or more embodiments. FIG. 5 illustrates an example configuration of an AIoT device, which relates to one or more embodiments.1A-1C illustrate example configurations of a base station and an intermediate node, respectively, in accordance with one or more embodiments.

[0048] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0049] The multiple embodiments described below may be used independently, or two or more embodiments may be combined as appropriate. These multiple embodiments may have different novel features. Therefore, these multiple embodiments may contribute to achieving different objectives or solving different problems, and may contribute to achieving different effects.

[0050] Each drawing is merely an example for describing one or more embodiments. Each drawing may not relate to only one particular embodiment, but may also relate to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0051] The following embodiments will be described with a focus on the 3GPP 5th generation mobile communication system (5G system), but may also be applied to other wireless communication systems that support AIoT devices.

[0052] As used herein, depending on the context, "if" may be interpreted to mean "when," "while," "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 to have the same meaning, depending on the context.

[0053] First, the configurations and operations of several network elements common to several embodiments will be described. Figures 1 to 4 show several example connection topologies for an AIoT device 1. Each element (network function) shown in Figures 1 to 4 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0054] The AIoT device 1 is an ambient power-enabled IoT device. The AIoT device 1 is an IoT device that is powered by energy harvesting and is battery-less or has limited energy storage capability (e.g., using a capacitor). Energy for the AIoT device 1 is supplied by harvesting radio waves, light, motion, heat, or other suitable power sources.

[0055] The types of AIoT devices 1 may be distinguished by whether they have power storage capabilities. Additionally or alternatively, the types of AIoT devices may be distinguished by the magnitude of their peak power consumption. Additionally or alternatively, the types of AIoT devices 1 may be distinguished by whether they have uplink amplification and / or downlink amplification. Additionally or alternatively, the types of AIoT devices 1 may be distinguished by whether their uplink transmissions are backscattered transmissions on an externally supplied carrier or generated by the device's active RF components.

[0056] In one example, the AIoT device 1 may be either of the first or second types described in Non-Patent Document 1. The first type of AIoT device has a peak power consumption of about 1 μW or less, has energy storage, and does not have downlink or uplink amplification within the device. The uplink transmission of the first type of AIoT device is backscattered on an externally supplied carrier. The second type of AIoT device has a power consumption of several hundred μW or less, has energy storage, and has one or both downlink and uplink amplification. The uplink transmission of the second type of AIoT device is backscattered transmission on an externally supplied carrier or is generated by active RF components within the device.

[0057] The AIoT device 1 may have a shift register or a control module. The shift register or the control module may store multiple control functions. The control function in the AIoT device 1 may be a pre-configured or pre-programmed control signaling function stored in the shift register (or memory). Alternatively, the control function in the AIoT device 1 may be a thin protocol state control module. The thin protocol state control module may be a control module with simpler functions than the RRC state control module of existing UEs (e.g., Release 18 UEs, Narrow Band IoT (NB-IoT) devices).

[0058] Figures 1, 2, 3, and 4 correspond to Topology 1, Topology 2, Topology 3 with Downlink Assistance, and Topology 3 with Uplink Assistance, respectively, shown in Non-Patent Document 2. In Topology 1 shown in Figure 1, AIoT devices 1 communicate directly and bidirectionally with base stations 2. Communication between base stations 2 and AIoT devices 1 includes AIoT data and / or signaling. Base stations 2 may include multiple base stations. The base station that performs downlink transmissions to AIoT devices 1 may be different from the base station that receives uplink transmissions from AIoT devices 1.

[0059] In Topology 2 shown in Figure 2, an AIoT device 1 communicates bidirectionally with an intermediate node 5 located between the device and a base station 2. The intermediate node 5 may be a relay, an IAB node, a UE, or a repeater, depending on the Ambient IoT. The intermediate node 5 transfers AIoT data and / or signaling between the base station 2 and the AIoT device 1.

[0060] In the topology 3 with downlink assistance shown in Figure 3, the AIoT device 1 transmits data and / or signaling to the base station 2 and receives data and / or signaling from the assist node 6. In the topology 3 with uplink assistance shown in Figure 4, the AIoT device 1 receives data and / or signaling from the base station 2 and transmits data and / or signaling to the assist node 6. The assist node 6 may be a relay, an IAB node, a UE, or a repeater, which is compatible with Ambient IoT.

[0061] In the connection topologies of Figures 1 to 4, the base station 2 belongs to a Radio Access Network (RAN) 3. The RAN 3 includes one or more base stations 2. The RAN 3 may be an NG Radio Access Network (NG-RAN), and the base station 2 may be a gNB.

[0062] The base station 2 may include one or more transmitting nodes and one or more receiving nodes. Each transmitting node is configured to transmit a wireless signal to the AIoT device 1. Each receiving node is configured to receive a wireless signal transmitted by the AIoT device 1.

[0063] In the connection topologies of Figures 1 to 4, a base station 2 or RAN 3 is connected to a Core Network (CN) 4. The CN 4 includes one or more core network nodes. These core network nodes include one or more control plane nodes and one or more user plane (or data plane) nodes. In the case of a 5G system, the control plane nodes include an Access and Mobility Management Function (AMF), a Session Management Function (SMF), and other nodes (e.g., a Unified Data Management (UDM) and a Policy Control Function (PCF)), and the user plane nodes include a User Plane Function (UPF).

[0064] Additionally or alternatively, the CN4 may include new control plane nodes and / or new user plane nodes for supporting AIoT devices, which may include, for example, AIoT management functions and / or AIoT application functions.

[0065] In the connection topologies of Figures 1 to 4, the RAN 3, CN 4, intermediate node 5 (in the case of topology 2), and assist node 6 (in the case of topology 3) may forward AIoT data from the AIoT device 1 to the application server. Similarly, the RAN 3, CN 4, intermediate node 5 (in the case of topology 2), and assist node 6 (in the case of topology 3) may forward AIoT data from the application server to the AIoT device 1.

[0066] The AIoT device 1 may be referred to by other terms such as an AIoT wireless terminal, an AIoT mobile terminal, an AIoT mobile station, an AIoT wireless transmit receive unit (WTRU), an AIoT UE, or a UE in Ambient IoT. The base station 2 may be referred to by other terms such as a RAN node, an access point, or a radio station.

[0067] The user plane protocol stack of the air interface between the AIoT device 1 and the base station 2, intermediate node 5, and assist node 6 may differ from that of the air interface of 3GPP Release 18 and earlier (e.g., Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), Evolved UTRA (E-UTRA), and NR). According to the current agreement of 3GPP RAN2, the Service Data Adaptation Protocol (SDAP) sublayer, Packet Data Convergence Protocol (PDCP) sublayer, and RLC sublayer may not be required in the AIoT user plane protocol stack. Hybrid automatic repeat request (HARQ) and RLC Acknowledged Mode (AM) may not be required. Per-packet Quality of Service (QoS) and per-flow QoS may not be supported at the AS level (both uplink and downlink).

[0068] Hereinafter, the base station 2, the intermediate node 5, and the assist node 6 are collectively referred to as the "leader." The term "leader" used below means the base station 2 (in the case of Topologies 1 and 3), the intermediate node 5 (in the case of Topology 2), the assist node 6 (in the case of Topology 3), or any combination thereof. Specifically, the leader may be the base station 2 in the case of Topology 1, the intermediate node 5 in the case of Topology 2, or one or a combination of the base station 2 and the assist node 6 in the case of Topology 3.

[0069] 5 shows an example of an inventory procedure. The inventory procedure may also be referred to as an inventory only procedure. In step 501, the CN4 (e.g., AIoT management function or AIoT application function) sends an inventory request message to the reader 8. As described above, the reader 8 may be a base station 2, an intermediate node 5, an assist node 6, or any combination thereof. The inventory request message may provide assistance information to the reader 8. The assistance information may include information for identifying one or more AIoT devices to be paged, such as one or more device IDs, device group IDs, or a mask (or matching filter).

[0070] If the reader 8 is an intermediate node 5, an assist node 6, or any combination thereof, the CN4 may send an inventory request message to the base station 2, and the base station 2 may further send the inventory request message to the reader 8 using the Uu interface. When transferring AIoT data and / or signaling using the Uu interface, the control plane or the user plane is used. Transfer of AIoT data and / or signaling via the control plane may use RRC signaling (including new signaling radio bearers), MAC control element (CE), and DL Control Information (DCI) format on the Uu interface. Transfer of AIoT data and / or signaling via the user plane may use dedicated data radio bearers.

[0071] In step 502, the reader 8 performs AIoT paging for inventory. Specifically, the reader 8 triggers or initiates a paging round by sending an R2D message for inventory. This R2D message is referred to herein as an initial trigger message or paging message. One paging round consists of one or more access occasions for slotted ALOHA.

[0072] The term "paging round" may be referred to by other terms such as an access round, an inventory round, a paging frame, or an access frame. The term "access occasion" may be referred to by other terms such as a time occasion, a slot, a time slot, an access slot, a response window, etc. The term "initial trigger message" or "paging message" may be referred to by other terms such as an initial paging message, a paging round initiation message, a paging round trigger message, an access round initiation message, an access round trigger message, an inventory round initiation message, or an inventory round trigger message.

[0073] The initial trigger message may include a random access (RA) setting. The RA setting may indicate the number of access occasions allocated to the paging round. To specify the number of one or more access occasions, the initial trigger message may indicate a Q value. In this case, the AIoT device may determine whether the number of access occasions in the paging round is equal to or greater than the Q power of 2 (i.e., 2 Q ) Additionally or alternatively, the RA configuration may indicate frequency resources, time resources, or both. The reader 8 may repeatedly transmit the initial trigger message so that AIoT devices that missed the initial trigger message can participate in the paging round.

[0074] In step 503, the AIoT device 1 sends an R2D message for an inventory response to the reader 8. The R2D message includes a device ID. In other words, the AIoT device 1 sends its own device ID (e.g., a device ID (AIoT device ID) of an upper layer).

[0075] In the case of an inventory of multiple AIoT devices, the AIoT device 1 transmits its device ID via contention-based RA (CBRA). The inventory of multiple AIoT devices may be an inventory targeted at a group of multiple AIoT devices, or may be an inventory targeted at all AIoT devices without including an AIoT ID. In CBRA, the AIoT device 1 randomly selects one of multiple access occasions within the paging round initiated by the initial trigger message and performs an RA procedure at the selected access occasion. The AIoT device 1 may perform a four-step-like (CB) RA procedure or a two-step-like (CB) RA procedure. The AIoT device 1 may also perform other types of random access procedures.

[0076] In the four-step-like (CB)RA procedure, the AIoT device 1 sends Msg1 containing its contention resolution ID (e.g., a random value, random ID) to the reader 8 at the selected access occasion. The contention resolution ID may also be called a temporary ID. Next, the AIoT device 1 receives Msg2 for contention resolution (e.g., an echoed contention resolution ID) from the reader 8. If contention resolution is successful, the AIoT device 1 sends Msg3 containing its device ID (upper layer device ID) to the reader 8. Msg3 may include other upper layer data. As explained in the Background section, the transmission of Msg4 in the four-step-like RA procedure may be omitted.

[0077] In a two-step-like (CB) RA procedure, the AIoT device 1 transmits Msg1, which includes its device ID (upper layer device ID) or a contention resolution ID (e.g., a random value, random ID) and its device ID, to the reader 8 in a selected access occasion. Following the terminology of NR random access, Msg1 in the two-step-like RA procedure may be referred to as message A (MsgA). The AIoT device 1 may receive Msg2 (e.g., an echoed contention resolution ID or (part of) the echoed device ID) from the reader 8. As explained in the Background section, the transmission of Msg2 in the two-step-like RA procedure may be omitted.

[0078] In step 504, the reader 8 sends the inventory response (e.g., device ID) received from the AIoT device 1 to the CN4.

[0079] As can be seen from the example of Figure 5 and as described in the Background section, communication between the AIoT device 1 and the reader 8 during the inventory procedure may be carried out in two steps: AIoT paging (step 502) and device ID transmission (step 503).

[0080] 6 shows an example of an inventory and command procedure. Steps 601 to 604 correspond to the inventory procedure. Steps 601 to 604 are similar to steps 501 to 504 in FIG.

[0081] In step 605, the CN4 (e.g., AIoT management function or AIoT application function) sends a command request to the reader 8. The command request targets any of the AIoT devices most recently inventoried in steps 601 to 604. The command may be a read command, a write command, or a disable command. A read command requests reading of data from the AIoT device 1. A write command requests storing or writing of data to the AIoT device 1. A disable command requests deactivation of the AIoT device. A disable command may request permanent deactivation of the AIoT device.

[0082] In step 606, the reader 8 sends an R2D message for a command request. The R2D message may indicate the device ID (e.g., AS Device ID) of the target AIoT device 1. The AS Device ID may be a different ID from the device ID (i.e., upper layer Device ID) sent in the inventory procedure (step 603), such as a part of the upper layer Device ID, or an ID suitable for the AIoT air interface that is shorter than the upper layer Device ID.

[0083] In step 607, the AIoT device 1 sends a D2R message to the reader 8 for a command response. In the case of a read command, the D2R message includes the data requested by the read command. In the case of a write command, the D2R message may indicate the AIoT device 1's feedback to the write command, such as an acknowledgement (ACK) or negative acknowledgement (NACK). In the case of an invalidation command, the D2R message may indicate the AIoT device 1's feedback to the invalidation command, such as an ACK or NACK.

[0084] In step 608, the reader 8 sends the command response received from the AIoT device 1 to the CN4.

[0085] 6, and as described in the Background section, communication between the AIoT device 1 and the reader 8 in the inventory and command procedure may be performed in four steps: AIoT paging (step 602), device ID transmission (step 603), command transmission (step 606), and command response (step 607). As described in the Background section, in some cases, the command response (step 607) may be omitted.

[0086] FIG. 7 shows an example of a command procedure. The command procedure may also be referred to as a command-only procedure. Steps 701 to 704 are similar to steps 605 to 608 in FIG. 6. The command-only procedure can be performed when the CN4, or the CN4 and the reader 8, know the device ID of the AIoT device. For example, the command-only procedure may be performed in a case where the AIoT device 1 recently performed an inventory procedure and the CN4 and the reader 8 still have valid context information (e.g., device ID). Alternatively, the command-only procedure may be performed in a case where the AIoT device 1 was inventoried a long time ago and the reader 8 does not have the context information (e.g., device ID) of the AIoT device 1, but the CN4 does.

[0087] Figures 8 and 9 show examples of AIoT paging and random access using slotted ALOHA. Figure 8 relates to a four-step-like (CB)RA. A leader 8 sends an initial trigger message 801. The initial trigger message 801 targets a group of AIoT devices or all AIoT devices. The initial trigger message 801 initiates a paging round 820. The paging round 820 consists of multiple access occasions, including access occasions #1 to #4.

[0088] The initial trigger message 801 includes information or a parameter (e.g., Q value) for specifying the number of access occasions in the paging round 820. Each of the multiple AIoT devices 1 randomly selects one of the multiple access occasions in the paging round 820 and attempts to transmit Msg1 including its own contention resolution ID (e.g., random value) in the selected access occasion.

[0089] Alternatively, if the initial trigger message 801 includes a single AIoT device ID or multiple IDs for multiple AIoT devices, the initial trigger message 801 may not include information or parameters for specifying the number of access occasions. In this case, each AIoT device 1 receiving the initial trigger message 801 may consider the number of access occasions to be equal to the number of AIoT devices to be paged. Each AIoT device 1 may understand that the order of its own ID within the list of one or more device IDs specified in the initial trigger message 801 corresponds to the ID or order of the access occasions assigned to it.

[0090] In the example of Figure 8, only AIoT device 1A sends Msg1 at access occasion #1. The contention resolution for this Msg1 is successful, and the leader 8 sends Msg2 indicating the contention resolution. In response to receiving Msg2, AIoT device 1A sends Msg3 (e.g., device ID, and optionally other upper layer data).

[0091] In the example of FIG. 8 , the initial trigger message 801 starts the first access occasion (i.e., access occasion #1) in the paging round 820. Alternatively, an access occasion start message for starting access occasion #1 may be transmitted separately from the initial trigger message 801. The reader 8 may transmit an independent access occasion start message for starting access occasion #1 after transmitting the initial trigger message 801. Such an implementation may be effective when the AIoT device 1A transmitting at access occasion #1 requires time for energy harvesting between receiving the initial trigger message 801 and starting to transmit Msg1.

[0092] Each subsequent access occasion is initiated by an access occasion start message. The term "access occasion start message" may be referred to by other terms such as access occasion trigger message, slot start message, slot trigger message, access slot start message, access slot trigger message, response window start message, response window trigger message, etc.

[0093] The access occasion start message 802 starts access occasion #2. In other words, the access occasion start message 802 notifies multiple AIoT devices 1 of the start of access occasion #2. Multiple AIoT devices 1 recognize the start of access occasion #2 based on receiving the access occasion start message 802. Multiple AIoT devices 1 may also recognize the end of access occasion #1 based on receiving the access occasion start message 802. In the example of FIG. 8, two AIoT devices 1B and 1C transmit Msg1 in access occasion #2. These two Msg1 transmissions collide, and contention resolution fails. Therefore, the leader 8 does not transmit Msg2. AIoT devices 1B and 1C detect a random access failure based on not receiving Msg2 for contention resolution.

[0094] The access occasion start message 803 starts access occasion #3. In other words, the access occasion start message 803 notifies multiple AIoT devices 1 of the start of access occasion #3. Multiple AIoT devices 1 recognize the start of access occasion #3 based on receiving the access occasion start message 803. Multiple AIoT devices 1 may also recognize the end of access occasion #2 based on receiving the access occasion start message 803. In the example of FIG. 8, access occasion #3 is idle. That is, since no AIoT device selected access occasion #3, Msg1 is not transmitted in access occasion #3. The leader 8 may end access occasion #3 and transmit an access occasion start message 804 to start the next access occasion #4 after the waiting time for receiving Msg1 has elapsed. For example, the leader 8 may determine that the waiting time for receiving Msg1 has elapsed by the expiration of a timer that was started upon transmission of the access occasion start message 803 for access occasion #3.

[0095] The access occasion start message 804 starts access occasion #4. In other words, the access occasion start message 804 notifies multiple AIoT devices 1 of the start of access occasion #4. Multiple AIoT devices 1 recognize the start of access occasion #4 based on receiving the access occasion start message 804. Multiple AIoT devices 1 may also recognize the end of access occasion #3 based on receiving the access occasion start message 804. In the example of FIG. 8, only AIoT device 1D sends Msg1 in access occasion #4. Contention resolution for this Msg1 is successful, and the leader 8 sends Msg2 indicating contention resolution. In response to receiving Msg2, AIoT device 1D sends Msg3 (e.g., device ID, and optionally other upper layer data).

[0096] The access occasion start message 805 starts access occasion #5. In other words, the access occasion start message 805 notifies multiple AIoT devices 1 of the start of access occasion #5. Multiple AIoT devices 1 recognize the start of access occasion #5 based on receiving the access occasion start message 805. Multiple AIoT devices 1 may also recognize the end of access occasion #4 based on receiving the access occasion start message 805.

[0097] FIG. 9 illustrates a two-step-like (CB)RA. The roles of the initial trigger message 901 and the access occasion initiation messages 902 to 905 are similar to those of the initial trigger message 801 and the access occasion initiation messages 802 to 805 shown in FIG. 8. Specifically, the initial trigger message 901 initiates a paging round 920. The paging round 920 consists of multiple access occasions, including access occasions #1 to #4. The access occasion initiation message for initiating access occasion #1 may be sent separately from the initial trigger message 901. After sending the initial trigger message 901, the leader 8 may send an independent access occasion initiation message for initiating access occasion #1. The access occasion initiation messages 902 to 905 initiate access occasions #2 to #5, respectively.

[0098] In the example of FIG. 9, only AIoT device 1A transmits Msg1 in access occasion #1. As described above, Msg1 of the 2-step-like RA may be referred to as MsgA. MsgA of the 2-step-like RA corresponds to Msg1 and Msg3 of the 4-step-like RA (FIG. 8). MsgA includes a device ID, or a contention resolution ID (e.g., a random value) and a device ID. MsgA may optionally include other upper layer data. Contention resolution for this MsgA is successful. The reader 8 may transmit Msg2 indicating contention resolution. AIoT device 1A may detect successful contention resolution and data transmission based on the reception of Msg2. However, as described above, transmission of Msg2 of the 2-step-like RA may be omitted regardless of whether contention resolution is successful or not.

[0099] In the example of Figure 9, two AIoT devices 1B and 1C transmit MsgA in access occasion #2. These two MsgA transmissions collide, and contention resolution fails. Therefore, the leader 8 does not transmit Msg2. AIoT devices 1B and 1C may detect a random access failure based on not receiving Msg2 for contention resolution.

[0100] In the example of Figure 9, access occasion #3 is idle. That is, since no AIoT device selected access occasion #3, MsgA is not transmitted during access occasion #3. The leader 8 may end access occasion #3 and transmit an access occasion start message 804 to start the next access occasion #4 when the waiting time for receiving MsgA has elapsed. For example, the leader 8 may determine that the waiting time for receiving MsgA has elapsed by detecting the expiration of a timer started upon transmission of the access occasion start message 903 for access occasion #3.

[0101] In the example of Figure 9, only AIoT device 1D transmits MsgA in access occasion #4. The contention resolution for this MsgA is successful. The leader 8 may transmit Msg2 indicating the contention resolution. The AIoT device 1D may detect the success of the contention resolution and the success of the data transmission based on the reception of Msg2. However, as described above, the transmission of Msg2 for the 2-step-like RA may be omitted regardless of whether the contention resolution is successful or not.

[0102] Figures 10 and 11 show examples of the operations of the AIoT device 1 and reader 8 in an inventory procedure using slotted ALOHA. These operations may be performed in the AIoT paging (step 502) and device ID transmission (step 503) of the inventory procedure in Figure 5. Additionally or alternatively, these operations may be performed in the AIoT paging (step 602) and device ID transmission (step 603) of the inventory and command procedure in Figure 6. Figure 10 relates to the case where the AIoT device 1 selects the first access occasion in the paging round. Meanwhile, Figure 11 relates to the case where the AIoT device 1 selects the second or subsequent access occasion in the paging round. In Figures 10 and 11, the AIoT device 1 uses a four-step-like RA procedure for device ID transmission in the selected access occasion.

[0103] 10, in step 1001, the reader 8 sends an initial trigger message. The initial trigger message indicates that a group of AIoT devices or all AIoT devices will be paged. The initial trigger message includes information or parameters (e.g., Q value) for specifying the number of access occasions in the paging round initiated by the initial trigger message.

[0104] The AIoT device 1 receives the initial trigger message. In step 1002, the AIoT device 1 randomly selects an access occasion within the paging round. Here, it is assumed that the AIoT device 1 selects the first access occasion #1.

[0105] In response to the selection of access occasion #1, the AIoT device 1 initiates a four-step-like RA procedure at access occasion #1. The four-step-like RA procedure includes sending Msg1 from the AIoT device 1 to the reader 8 (step 1003), sending Msg2 from the reader 8 to the AIoT device 1 (step 1004), and sending Msg3 from the AIoT device 1 to the reader 8 (step 1005). The four-step-like RA procedure may also include sending Msg4 from the reader 8 to the AIoT device 1 (step 1006).

[0106] As described above, an access occasion start message for starting access occasion #1 may be sent separately from the initial trigger message (1001). In this case, the AIoT device 1 that selects access occasion #1 also operates as shown in FIG.

[0107] Referring to Figure 11, steps 1101 and 1102 are similar to steps 1001 and 11002 in Figure 10. However, in step 1102, it is assumed that the AIoT device 1 selects the second or later first access occasion #n in the paging round.

[0108] In step 1103, the reader 8 sequentially transmits multiple access occasion start messages. Each of the multiple access occasion start messages starts a respective one of the second and subsequent access occasions. In response to receiving the access occasion start message for access occasion #n, the AIoT device 1 initiates a four-step-like RA procedure for access occasion #n. Steps 1104 to 1107 are similar to steps 1003 to 1006 in FIG. 10.

[0109] 12 and 13 show other examples of the operations of the AIoT device 1 and reader 8 in an inventory procedure using slotted ALOHA. These operations may be performed in the AIoT paging (step 502) and device ID transmission (step 503) of the inventory procedure in FIG. 5. Additionally or alternatively, these operations may be performed in the AIoT paging (step 602) and device ID transmission (step 603) of the inventory and command procedure in FIG. 6. FIG. 12 relates to the case where the AIoT device 1 selects the first access occasion in the paging round. On the other hand, FIG. 13 relates to the case where the AIoT device 1 selects the second or subsequent access occasion in the paging round. In FIGS. 12 and 13, the AIoT device 1 uses a two-step-like RA procedure for device ID transmission in the selected access occasion.

[0110] The procedure in Figure 12 is the same as the procedure in Figure 10, except that a two-step-like RA procedure is used instead of a four-step-like RA procedure. Steps 1201 and 1202 correspond to steps 1001 and 1002 in Figure 10. In response to selecting access occasion #1, AIoT device 1 initiates a two-step-like RA procedure at access occasion #1. The two-step-like RA procedure includes sending Msg1 (or MsgA) from the AIoT device 1 to the reader 8 (step 1203). The two-step-like RA procedure may also include sending Msg2 from the reader 8 to the AIoT device 1 (step 1204).

[0111] The procedure in Figure 13 is the same as the procedure in Figure 11, except that a two-step-like RA procedure is used instead of a four-step-like RA procedure. Steps 1301, 1302, and 1303 correspond to steps 1101, 1102, and 1103 in Figure 11. In response to selecting access occasion #n, the AIoT device 1 initiates a two-step-like RA procedure at access occasion #n. The two-step-like RA procedure includes sending Msg1 (or MsgA) from the AIoT device 1 to the reader 8 (step 1304). The two-step-like RA procedure may also include sending Msg2 from the reader 8 to the AIoT device 1 (step 1305).

[0112] <First Embodiment> This embodiment relates to determining or selecting an RA procedure to be used for AIoT access. Figure 14 shows an example of the operation of an AIoT device 1 and a reader 8. In step 1401, the reader 8 transmits an R2D message. The AIoT device 1 receives the R2D message. The R2D message triggers or causes random access by one or more AIoT devices. The R2D message may be an initial trigger message, which is a message that starts a single paging round including multiple access occasions.

[0113] The R2D message of step 1401 includes information specifying whether one or both of the first type RA procedure and the second type RA procedure are allowed. The information may be included in the RA configuration. The information may indicate whether the first type RA procedure, the second type RA procedure, or both the first type and the second type RA procedure are allowed. The first type RA procedure and the second type RA procedure may be a four-step-like RA procedure and a two-step-like RA procedure.

[0114] The AIoT device 1 determines whether to perform one or both of the first type RA procedure and the second type RA procedure based on the information included in the received R2D message (1401). The AIoT device 1 may determine whether to perform one or both of the first type RA procedure and the second type RA procedure in one or more of multiple access occasions in a paging round initiated by an R2D message (e.g., an initial trigger message). The AIoT device 1 may determine whether to perform the first type RA procedure, the second type RA procedure, or neither the first type RA procedure nor the second type RA procedure.

[0115] For example, if the R2D message (1401) indicates that a first type of RA procedure is permitted but a second type of RA procedure is not permitted, and the AIoT device 1 selects, decides, or desires the second type of RA procedure, the AIoT device 1 may decide not to perform random access. Alternatively, if the R2D message indicates that a first type of RA procedure is permitted but a second type of RA procedure is not permitted, and the AIoT device 1 has not configured or does not support the first type of RA procedure, the AIoT device 1 may decide not to perform random access. In these cases, the AIoT device 1 may ignore the R2D message.

[0116] If the R2D message (e.g., initial trigger message) indicates that both the first and second type of RA procedure are allowed, the R2D message may further include the following information: The R2D message may include one or more parameters for defining a first (sub)set of access occasions for the first type of RA procedure and a second (sub)set of access occasions for the second type of random access procedure, separate from the first set.

[0117] In one example, these parameters may include a first parameter (e.g., a normal Q value) for specifying the total number of access occasions, and a second parameter for specifying the number of access occasions belonging to a first (sub)set for the first type of RA procedure. The number of access occasions belonging to the first (sub)set may be specified as a power of two, and the second parameter may indicate an exponent (e.g., a Q' value). The Q' value is an integer greater than or equal to 0 and less than the Q value. The AIoT device 1 may receive the first (sub)set from the beginning of the paging round. Q' access occasions belong to the first (sub)set, and the remaining 2 Q -2 Q' This access occasion may be understood to belong to the second (sub)set.

[0118] In another example, these parameters may include a first parameter (e.g., Q' value) for specifying the number of access occasions belonging to a first (sub)set for a first type of RA procedure, and a second parameter (e.g., Q'' value) for specifying the number of access occasions belonging to a second (sub)set for a second type of RA procedure. Q' The access occasions belong to the first (sub)set, and the next two access occasions belong to the first (sub)set. Q'' This access occasion may be understood to belong to the second (sub)set.

[0119] In yet another example, these parameters may be only a first parameter (e.g., a normal Q value) for specifying the total number of access occasions, in which case the AIoT device 1 may understand that the first half of the access occasions in the paging round belong to the first (sub)set and the second half of the access occasions belong to the second (sub)set.

[0120] The maximum size of the D2R message transmitted at each access occasion in the first set for the first type RA procedure may be the same as or different from the maximum size of the D2R message transmitted at each access occasion in the second set for the second type RA procedure. Additionally or alternatively, the maximum transmission duration of the Physical Device to Reader Channel (PDRCH) carrying the D2R message transmitted at each access occasion in the first set may be the same as or different from that of the PDRCH transmitted at each access occasion in the second set for the second type RA procedure. The PDRCH is a physical channel transmitted by the AIoT device 1 to the reader 8 and carrying the D2R message.

[0121] The operations described with reference to Figure 14 can provide a specific example of a method for selecting or configuring one of multiple RA procedures to be used for AIoT access. Specifically, according to the operations of Figure 14, the reader 8 specifies one or more allowed types of RA procedures in an R2D message (e.g., an initial trigger message) for triggering or causing random access by one or more AIoT devices. The AIoT device 1 receives the R2D message from the reader 8 and determines the RA procedure to use for AIoT access according to the instructions in the received R2D message.

[0122] <Second Embodiment> This embodiment relates to determining or selecting an RA procedure to be used for AIoT access. Figure 15 shows an example of the operation of an AIoT device 1. In step 1501, the AIoT device 1 receives an R2D message. The R2D message may be an initial trigger message.

[0123] In step 1502, the AIoT device 1 autonomously determines whether to perform a first-type RA procedure or a second-type RA procedure. The first-type RA procedure and the second-type RA procedure may be a four-step-like RA procedure and a two-step-like RA procedure. For example, the AIoT device 1 may determine whether to use the first-type RA procedure or the second-type RA procedure based on the size of data transmitted in the access occasion. If the size of data transmitted in the access occasion exceeds a threshold, the AIoT device 1 may use the four-step-like RA procedure; otherwise, the AIoT device 1 may use the two-step-like RA procedure. The threshold may be compared with the length of the PDU (e.g., MAC PDU) containing the D2R message, the length of the PDRCH carrying the D2R message, the transmission duration of the PDRCH, or the length of the access occasion in which the PDRCH is transmitted. The threshold may be predefined or specified by the R2D message (1501). The threshold may be indicated using a dedicated field in the R2D message (1501).

[0124] In step 1503, the AIoT device 1 communicates with the reader 8 in accordance with the RA procedure determined in step 1502 in one or more of multiple access occasions within a paging round initiated by the R2D message received in step 1501.

[0125] When the AIoT device 1 transmits an RA first message (Msg1) in an access occasion, it may include an indication of the determined RA procedure in the Msg1, a Protocol Data Unit (PDU) (e.g., MAC PDU) or data block containing the Msg1, or a PDRCH carrying the Msg1. The PDRCH is a physical channel transmitted by the AIoT device 1 to the reader 8. This allows the reader 8 to easily know whether the Msg1 relates to the first type RA procedure or the second type RA procedure by receiving the Msg1, the PDU or data block containing the Msg1, or the PDRCH carrying the Msg1.

[0126] The AIoT device may include or add a predetermined end marker or postamble at the end of Msg1, the end of the PDU or data block containing Msg1, or the end of the PDRCH carrying Msg1. The size of Msg1 in a first type RA procedure (e.g., a four-step-like RA procedure) may be different from the size of Msg1 in a second type RA procedure (e.g., a two-step-like RA procedure). The reader 8 can easily detect the end of Msg1 by receiving or decoding the end marker or postamble.

[0127] The operations described with reference to Figure 15 can provide a specific example of a method for selecting or configuring one of multiple RA procedures to be used for AIoT access. Specifically, according to the operations of Figure 15, the AIoT device 1 autonomously determines the RA procedure to use for AIoT access. The reader 8 does not need to specify which type of random access procedure is allowed in the R2D message (e.g., initial trigger message).

[0128] Figure 16 shows an example of the format of Msg1 of a four-step-like RA procedure or a PDU (or data block) containing it. Figure 17 shows an example of the format of Msg1 of a two-step-like RA procedure or a PDU (or data block) containing it. As mentioned above, Msg1 of a two-step-like RA procedure may be called MsgA.

[0129] 16, Msg1 (or PDU, or data block) 1600 of the four-step-like RA procedure includes an indication 1601 of the four-step RA procedure at its beginning. The indication 1601 may be an indication of a four-step-like RA or an indication of Msg1 of a four-step-like RA (e.g., Indication of Msg1). Msg1 (or PDU, or data block) 1600 includes content 1602 of Msg1 of the four-step-like RA procedure and further includes an end marker 1603 at its end.

[0130] 17, MsgA (or PDU, or data block) 1700 of the two-step-like RA procedure includes an indication 1701 of the two-step RA procedure at its beginning. The indication 1701 may be an indication of the two-step-like RA or an indication (e.g., Indication of MsgA) of Msg1 (or MsgA) of the two-step-like RA. MsgA (or PDU, or data block) 1700 includes contents 1702 of MsgA of the two-step-like RA procedure and further includes an end marker 1703 at its end.

[0131] <Third Embodiment> This embodiment relates to a method of using CRDSA in multiple Msg1 transmissions by multiple AIoT devices in a two-step-like RA procedure. As described above, it has been agreed that the baseline for AIoT random access is slotted ALOHA. In AIoT random access based on slotted ALOHA, one paging round is divided into multiple access occasions. Each AIoT device can only transmit a data packet (e.g., Msg1 or MsgA) at the selected access occasion. If multiple AIoT devices select the same access occasion to transmit data packets, a collision occurs, and all colliding packets may result in access failure.

[0132] To mitigate the throughput degradation caused by packet collisions in slotted ALOHA, Diversity Slotted ALOHA (DSA) is known. In DSA, each AIoT device transmits two or more replicas of a data packet on two or more access occasions. However, in high-load scenarios, the number of replicas becomes too large, resulting in frequent collisions and a rapid degradation of throughput.

[0133] To further mitigate the packet collision problem in slotted ALOHA, contention resolution DSA (CRDSA) is known. CDRSA effectively combines packet diversity transmission and iterative interference cancellation to improve throughput. Each AIoT device transmits two or more replicas of a data packet at two or more randomly selected access occasions. The receiver, or reader, first decodes a packet with little or no interference at one access occasion. The reader then cancels the interference caused by the replicas at other access occasions using the demodulated packet. By performing interference cancellation iteratively, the reader can decode multiple data packets received from multiple AIoT devices at multiple access occasions.

[0134] CRDSA may be particularly suitable for a two-step-like RA procedure for AIoT access. In a two-step-like RA procedure, the transmission of Msg2 can be omitted. In this case, as long as the reader 8 successfully decodes Msg1 (MsgA) that an AIoT device attempts to transmit in an RA, the RA can be considered to have been completed successfully. When CRDSA is applied to a two-step-like RA procedure, the reader uses an AIoT device's Msg1 successfully decoded in an access occasion to cancel interference caused by a replica of that Msg1 in a previous access occasion. This allows the reader to successfully decode Msg1s from other AIoT devices that were received in the previous access occasion. By repeatedly performing interference cancellation, the reader can successfully decode multiple Msg1s for multiple two-step-like RAs in multiple access occasions and successfully complete these multiple two-step-like RAs.

[0135] Figure 18 shows an example of the operation of an AIoT device 1 and a reader 8 in relation to a two-step-like RA using DSA or CRDSA. In step 1801, the reader 8 transmits an R2D message. The AIoT device 1 receives the R2D message. The R2D message triggers or causes random access by one or more AIoT devices. The R2D message may be an initial trigger message, which initiates a single paging round that includes multiple access occasions.

[0136] The R2D message of step 1801 includes a first parameter and a second parameter. The first parameter included in the R2D message defines or specifies the number of access occasions in one paging round. The first parameter may indicate the above-mentioned Q value. In this case, the AIoT device determines whether the number of access occasions in the paging round is equal to or greater than the Q power of 2 (i.e., 2 Q ) is understood to be.

[0137] The second parameter included in the R2D message defines or specifies the number of replicas (e.g., 2 or more) of the first message (Msg1 or MsgA) of the two-step-like RA procedure transmitted within the paging round. The second parameter may indicate the number of replicas (e.g., 2, 3, 4, ...).

[0138] Figure 19 shows an example of the operation of the AIoT device 1. Step 1901 corresponds to step 1801 in Figure 18. In step 1902, the AIoT device 1 randomly selects access occasions equal to the number of replicas using the above-mentioned first and second parameters received via the R2D message (step 1901). In step 1903, the AIoT device 1 attempts to send two or more replicas of the two-step-like RA Msg1 (MsgA) to the leader 8 in the two or more selected access occasions.

[0139] The operation of the AIoT device 1 and reader 8 described with reference to Figures 18 and 19 can provide details for using DSA or CRDSA in multiple Msg1 transmissions by multiple AIoT devices in a two-step-like RA procedure.

[0140] If the Msg1 replica transmission in one of the selected two or more access occasions is successful, the AIoT device 1 may cancel the Msg1 replica transmission in the remaining one or more access occasions. Specifically, the AIoT device 1 may operate as shown in Figure 20. Figure 20 shows an example of the operation of the AIoT device 1 in a two-step-like RA procedure using DSA or CRDSA.

[0141] In step 2001, the AIoT device 1 sends a replica of MsgA to the leader 8 in one of the two or more selected access occasions. In step 2002, the AIoT device 1 receives Msg2 of the two-step-like RA from the leader 8. In step 2003, if Msg2 indicates that Msg1 was successfully received, the AIoT device 1 cancels the transmission of the Msg1 replica in one or more remaining access occasions of the two or more selected access occasions.

[0142] To cancel the transmission of the Msg1 replica, the AIoT device 1 may set a counter for determining the arrival of a selected access occasion to an invalid value (e.g., -1). This counter may be called an occasion counter or a slot counter. At the start of the paging round, the AIoT device 1 selects two or more access occasions and sets the initial values ​​corresponding to the selected access occasions to two or more occasion counters. For example, if the AIoT device 1 receives a Q value, it sets the Q value from 0 to 2. Q An integer value between -1 and 2 or more may be randomly selected, and the selected value may be set to an occasion counter of 2 or more.

[0143] In response to receiving the access occasion start message, the AIoT device 1 decrements two or more occasion counters. If any of the occasion counters reaches a predetermined value (e.g., zero), the AIoT device 1 attempts a two-step-like RA procedure for that access occasion. In that access occasion, the AIoT device 1 sends Msg1. If the AIoT device 1 subsequently receives Msg2 from the reader 8, it sets one or more remaining occasion counters to an invalid value (e.g., -1).

[0144] According to the operation described with reference to Figure 20, the AIoT device 1 can avoid unnecessary replica transmission in a two-step-like RA procedure using DSA or CRDSA.

[0145] <Fourth Embodiment> This embodiment relates to the use of Msg4 in a four-step-like RA procedure and the use of Msg2 in a two-step-like RA procedure. As described above, 3GPP RAN2 has agreed that Msg4 in a four-step-like RA procedure does not necessarily need to be transmitted. Similarly, 3GPP RAN2 has agreed that Msg2 in a two-step-like RA procedure does not necessarily need to be transmitted. In this embodiment, when a second trigger message is used in the inventory procedure, Msg4 in a four-step-like RA procedure or Msg2 in a two-step-like RA procedure is used. On the other hand, when a second trigger message is not used in the inventory procedure, neither Msg4 in a four-step-like RA procedure nor Msg2 in a two-step-like RA procedure is used.

[0146] When a second trigger message is used in the inventory procedure, the reader 8 and the AIoT device 1 operate as follows: In a four-step-like RA procedure performed in an access occasion within a paging round initiated by an initial trigger message, the reader 8 sends Msg4 to indicate to the AIoT device 1 whether it has successfully received Msg3. The AIoT device 1 attempts to receive Msg4 after sending Msg3. Similarly, in a two-step-like RA procedure performed in an access occasion within a paging round initiated by an initial trigger message, the reader 8 sends Msg2 to indicate to the AIoT device 1 whether it has successfully received Msg1 (or MsgA). The AIoT device 1 attempts to receive Msg2 after sending Msg1 (or MsgA).

[0147] If a second trigger message is not used in the inventory procedure, the reader 8 and the AIoT device 1 operate as follows: In a four-step-like RA procedure performed in an access occasion within a paging round initiated by an initial trigger message, the reader 8 does not send Msg4. The AIoT device 1 does not need to attempt to receive Msg4 after sending Msg3. Similarly, in a two-step-like RA procedure performed in an access occasion within a paging round initiated by an initial trigger message, the reader 8 does not send Msg2. The AIoT device 1 does not need to attempt to receive Msg2 after sending Msg1 (or MsgA).

[0148] The second trigger message triggers an additional paging round. The second trigger message causes AIoT devices that did not receive Msg2 or Msg4 in the four-step-like RA procedure at any access occasion within the paging round to transmit in the additional paging round initiated by the second trigger message. Similarly, the second trigger message causes AIoT devices that did not receive Msg2 in the two-step-like RA procedure at any access occasion within the paging round to transmit in the additional paging round initiated by the second trigger message.

[0149] The initial trigger message may include an indication of whether a second trigger message will be used, allowing the AIoT device 1 to know whether a second trigger message will be used for the current inventory procedure. Based on the indication that a second trigger message will be used, the AIoT device 1 determines that reception of Msg4 in a four-step-like RA procedure or Msg2 in a two-step-like RA procedure is necessary or expected.

[0150] Next, configuration examples of the AIoT device 1, base station 2, intermediate node 5, and assist node 6 related to the above-described embodiments will be described below. FIG. 21 shows a configuration example of the AIoT device 1. Referring to FIG. 21, the AIoT device 1 includes an energy harvester 2101, a power management 2102, an energy storage 2103, a controller 2104, a memory 2105, an RF circuit 2106, and an antenna 2107. The energy harvester 2101 converts radio waves, light, motion, heat, or other energy into electric power. The power management 2102 stores the electric power generated by the energy harvester 2101 in the energy storage 2103 (e.g., a capacitor) and controls the power supply to the controller 2104, the memory 2105, and the RF circuit 2106.

[0151] Controller 2104 receives signaling, data, and signals via RF circuitry 2106. Controller 2104 accesses memory 2105 and generates signaling, data, and signals that are transmitted via RF circuitry 2106. Controller 2104 may be pre-set or pre-programmed control signaling functions stored in memory 2105 (e.g., shift registers). Alternatively, controller 2104 may be a thin protocol state control module.

[0152] The RF circuit 2106 is coupled to an antenna 2107. If the AIoT device 1 is a device that performs backscatter communication, the RF circuit 2106 may include RF circuits such as a demodulator and a modulator (frequency multiplier). If the AIoT device 1 generates an uplink signal using its own active RF components, the RF circuit 2106 may be an active RF transceiver.

[0153] Figure 22 shows an example configuration of the base station 2. Referring to Figure 22, the base station 2 includes an RF transceiver 2201, a network interface 2203, a processor 2204, and a memory 2205. The RF transceiver 2201 performs analog RF signal processing for communicating with the AIoT device 1, the intermediate node 5, the assist node 6, and other UEs. The RF transceiver 2201 may include multiple transceivers. In particular, the RF transceiver 2201 may include one or more transceivers for a Uu interface with the intermediate node 5, the assist node 6, and other UEs, and a transceiver for communicating with multiple AIoT devices including the AIoT device 1. In addition to the RF transceiver 2201, the base station 2 may also include an RF transmitter for supplying RF power to the AIoT devices.

[0154] The RF transceiver 2201 is coupled to the antenna array 2202 and the processor 2204. For example, the RF transceiver 2201 receives modulation symbol data from the processor 2204, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 2202. The RF transceiver 2201 also generates a baseband receive signal based on the receive RF signal received by the antenna array 2202 and provides the baseband receive signal to the processor 2204. The RF transceiver 2201 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, multiple phase shifters and multiple power amplifiers.

[0155] The network interface 2203 is used to communicate with network nodes (e.g., other base stations, control plane nodes and user plane nodes in the CN4), and may include, for example, a network interface card (NIC) conforming to the IEEE 802.3 series.

[0156] The processor 2204 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 2204 may include multiple processors. For example, the processor 2204 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing.

[0157] For example, digital baseband signal processing by processor 2204 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. Control plane processing by processor 2204 may also include processing of Non-Access Stratum (NAS) messages, RRC messages, MAC Control Elements (CEs), and Downlink Control Information (DCI).

[0158] The processor 2204 may include a digital beamformer module for beamforming, which may include a Multiple Input Multiple Output (MIMO) encoder and precoder.

[0159] The memory 2205 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, Static Random Access Memory (SRAM), Dynamic RAM (DRAM), or a combination thereof. The non-volatile memory is, for example, Mask Read Only Memory (MROM), Electrically Erasable Programmable ROM (EEPROM), flash memory, or a hard disk drive, or any combination thereof. The memory 2205 may include storage located remotely from the processor 2204. In this case, the processor 2204 may access the memory 2205 via the network interface 2203 or an I / O interface (not shown).

[0160] The memory 2205 may store one or more software modules (computer programs) 2206 including instructions and data for performing the processes of the base station 2 described in the above embodiments. In some implementations, the processor 2204 may be configured to read and execute the software modules 2206 from the memory 2205 to perform the processes of the base station 2 described in the above embodiments.

[0161] It should be noted that the control plane processing and operations performed by the base station 2 described in the above embodiment can be realized by elements other than the RF transceiver 2201 and the antenna array 2202, namely the processor 2204 and the memory 2205 storing the software module 2206.

[0162] Figure 23 shows an example configuration of the intermediate node 5. In the example of Figure 23, the intermediate node 5 is a UE. The configuration of the assist node 6 may also be similar to the configuration shown in Figure 23. The RF transceiver 2301 performs analog RF signal processing to communicate with the base station 2. In addition, the RF transceiver 2301 performs analog RF signal processing to communicate with multiple AIoT devices including the AIoT device 1. The RF transceiver 2301 may include multiple transceivers. In particular, the RF transceiver 2301 may include one or more transceivers for a Uu interface with the base station 2 and a transceiver for communicating with multiple AIoT devices including the AIoT device 1.

[0163] The analog RF signal processing performed by the RF transceiver 2301 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 2301 is coupled to the antenna array 2302 and the baseband processor 2303. For example, the RF transceiver 2301 receives modulation symbol data (or orthogonal frequency-division multiplexing (OFDM) symbol data) from the baseband processor 2303, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 2302. The RF transceiver 2301 also generates a baseband receive signal based on the receive RF signal received by the antenna array 2302 and provides it to the baseband processor 2303. The RF transceiver 2301 may include an analog beamformer circuit for beamforming. The analog beamformer circuit includes, for example, multiple phase shifters and multiple power amplifiers.

[0164] The baseband processor 2303 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communications. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management for 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 attachment, mobility, and call management).

[0165] For example, the digital baseband signal processing by the baseband processor 2303 may include signal processing of the SDAP layer, PDCP layer, RLC layer, MAC layer, and PHY layer. Also, the control plane processing by the baseband processor 2303 may include processing of the Non-Access Stratum (NAS) protocol, the RRC protocol, MAC CEs, and DCIs.

[0166] The baseband processor 2303 may perform MIMO encoding and precoding for beamforming.

[0167] The baseband processor 2303 may include a modem processor (e.g., DSP) that performs digital baseband signal processing and a protocol stack processor (e.g., CPU or 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 2304, which will be described later.

[0168] The application processor 2304 is also called a CPU, MPU, microprocessor, or processor core. The application processor 2304 may include multiple processors (multiple processor cores). The application processor 2304 executes a system software program (operating system (OS)) and various application programs read from the memory 2306 or a memory not shown, thereby realizing various functions of the intermediate node 5.

[0169] In some implementations, the baseband processor 2303 and the application processor 2304 may be integrated on a single chip, as shown by the dashed line (2305) in Figure 23. In other words, the baseband processor 2303 and the application processor 2304 may be implemented as a single System on Chip (SoC) device 2305. An SoC device is sometimes called a system Large Scale Integration (LSI) or chipset.

[0170] The memory 2306 is volatile memory, nonvolatile memory, or a combination thereof. The memory 2306 may include multiple physically independent memory devices. The volatile memory is, for example, SRAM, DRAM, or a combination thereof. The nonvolatile memory is, for example, MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. For example, the memory 2306 may include an external memory device accessible from the baseband processor 2303, the application processor 2304, and the SoC 2305. The memory 2306 may also include an internal memory device integrated within the baseband processor 2303, the application processor 2304, or the SoC 2305. Furthermore, the memory 2306 may include memory within a Universal Integrated Circuit Card (UICC).

[0171] The memory 2306 may store one or more software modules (computer programs) 2307 including instructions and data for performing the processing by the intermediate node 5 described in the above-described embodiments. In some implementations, the baseband processor 2303 or the application processor 2304 may be configured to read and execute the software modules 2307 from the memory 2306, thereby performing the processing by the intermediate node 5 described in the above-described embodiments using the drawings.

[0172] It should be noted that the control plane processing and operations performed by the intermediate node 5 described in the above embodiment can be realized by elements other than the RF transceiver 2301 and the antenna array 2302, namely, at least one of the baseband processor 2303 and the application processor 2304, and the memory 2306 storing the software module 2307.

[0173] As described with reference to FIGS. 21 to 23 , each of the processors included in the AIoT device 1, base station 2, intermediate node 5, and assist node 6 according to the above-described embodiments can execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray (registered trademark) disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0174] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0175] For example, some or all of the above embodiments may also be described as, but are not limited to, the following appendices. Some or all of the elements (e.g., configurations and functions) described in appendices directed to apparatuses (e.g., AIoT devices, readers) may naturally also be described as appendices directed to methods and programs. For example, some or all of the elements described in appendices 2-12, which are dependent on appendices 1, may also be described as appendices dependent on appendices 13 and 14, due to the same dependency relationship as appendices 2-12. Similarly, some or all of the elements described in appendices 16-26, which are dependent on appendices 15, may also be described as appendices dependent on appendices 27 and 28, due to the same dependency relationship as appendices 16-26. Some or all of the elements described in any appendice may be applicable to various hardware, software, recording means for recording software, systems, and methods.

[0176] (Supplementary Note 1) An AIoT device comprising: means for receiving a reader to device (R2D) message used to trigger or cause random access by one or more AIoT devices and specifying one or both of a first type random access procedure and a second type random access procedure as being permitted; and means for determining whether to perform one or both of the first type random access procedure and the second type random access procedure based on the R2D message. (Supplementary Note 2) The AIoT device of Supplementary Note 1, wherein the first type random access procedure is a four-step-like random access procedure, and the second type random access procedure is a two-step-like random access procedure. (Supplementary Note 3) The AIoT device of Supplementary Note 1 or 2, wherein the R2D message indicates whether the first type random access procedure, the second type random access procedure, or both the first type and the second type random access procedures are permitted. (Supplementary Note 4) The AIoT device of any one of Supplements 1 to 3, wherein the determining means is configured to determine, based on the R2D message, whether to perform the first type random access procedure, the second type random access procedure, or neither the first type random access procedure nor the second type random access procedure. (Supplementary Note 5) The AIoT device of any one of Supplements 1 to 4, wherein the determining means is configured to determine, based on the R2D message, whether to perform one or both of the first type random access procedure and the second type random access procedure in one or more of a plurality of access occasions in one paging round initiated by the R2D message.(Supplementary Note 6) The AIoT device of any one of Supplements 1 to 5, further comprising: means for ignoring the R2D message if the R2D message indicates that the first type random access procedure is allowed but the second type random access procedure is not allowed, and if the determining means decides to perform the second type random access procedure. (Supplementary Note 7) The AIoT device of any one of Supplements 1 to 5, further comprising: means for ignoring the R2D message if the R2D message indicates that the first type random access procedure is allowed but the second type random access procedure is not allowed, and if the AIoT device is not configured for or does not support the first type random access procedure. (Supplementary Note 8) The AIoT device of any one of Supplements 1 to 7, further comprising: means for defining a first set of access occasions for the first type random access procedure and a second set of access occasions for the second type random access procedure separated from the first set, if the R2D message indicates that both the first type and the second type random access procedures are allowed. (Supplementary Note 9) The AIoT device of Supplementary Note 8, wherein a maximum size of a device to reader (D2R) message transmitted at each access occasion in the first set is different from a maximum size of a D2R message transmitted at each access occasion in the second set. (Supplementary Note 10) The AIoT device of Supplementary Note 8, wherein a maximum transmission duration of a physical channel carrying a device to reader (D2R) message transmitted at each access occasion in the first set is different from a maximum transmission duration of a physical channel carrying a D2R message transmitted at each access occasion in the second set. (Supplementary Note 11) The AIoT device of any one of Supplements 1 to 10, wherein the R2D message initiates one paging round including multiple access occasions.(Supplementary Note 12) The AIoT device according to any one of Supplements 1 to 11, wherein the R2D message is a paging message or an initial trigger message sent by a reader. (Supplementary Note 13) A method performed by an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message used to trigger or cause random access by one or more AIoT devices and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed; and determining whether to perform one or both of the first type of random access procedure and the second type of random access procedure based on the R2D message. (Supplementary Note 14) A program for causing a computer to perform a method for an AIoT device, the method comprising: receiving a reader to device (R2D) message used to trigger or cause random access by one or more Ambient Internet of Things (AIoT) devices and specifying one or both of a first type random access procedure and a second type random access procedure that are allowed, and determining whether to perform one or both of the first type random access procedure and the second type random access procedure based on the R2D message. (Supplementary Note 15) A reader, comprising: means for sending a reader to device (R2D) message used to trigger or cause random access by one or more Ambient Internet of Things (AIoT) devices and specifying one or both of a first type random access procedure and a second type random access procedure that are allowed, the R2D message causing the AIoT device to determine whether to perform one or both of the first type random access procedure and the second type random access procedure.(Supplementary Note 16) The reader according to Supplementary Note 15, wherein the first type random access procedure is a four-step-like random access procedure, and the second type random access procedure is a two-step-like random access procedure. (Supplementary Note 17) The reader according to Supplementary Note 15 or 16, wherein the R2D message indicates whether the first type random access procedure, the second type random access procedure, or both the first type and the second type random access procedures are allowed. (Supplementary Note 18) The reader according to any one of Supplements 15 to 17, wherein the R2D message causes an AIoT device to decide whether to perform the first type random access procedure, the second type random access procedure, or neither the first type random access procedure nor the second type random access procedure. (Supplementary Note 19) The reader of any one of Supplements 15 to 18, wherein the R2D message causes the AIoT device to decide whether to perform one or both of the first type random access procedure and the second type random access procedure in one or more of a plurality of access occasions in one paging round initiated by the R2D message. (Supplementary Note 20) The reader of any one of Supplements 15 to 19, wherein if the R2D message indicates that the first type random access procedure is allowed but the second type random access procedure is not allowed, and if the AIoT device decides to perform the second type random access procedure, the R2D message causes the AIoT device to ignore the R2D message. (Supplementary Note 21) The reader of any one of Supplementary Notes 15 to 19, wherein if the R2D message indicates that the first type of random access procedure is allowed but the second type of random access procedure is not allowed, and if the AIoT device is not configured or does not support the first type of random access procedure, the R2D message causes the AIoT device to ignore the R2D message.(Supplementary Note 22) The reader according to any one of Supplements 15 to 21, wherein, when the R2D message indicates that both the first type and the second type random access procedures are allowed, the R2D message includes one or more parameters for defining a first set of access occasions for the first type random access procedure and a second set of access occasions for the second type random access procedure separated from the first set. (Supplementary Note 23) The reader according to Supplementary Note 22, wherein a maximum size of a device to reader (D2R) message transmitted on each access occasion in the first set is different from a maximum size of a D2R message transmitted on each access occasion in the second set. (Supplementary Note 24) The reader according to Supplementary Note 22, wherein a maximum transmission duration of a physical channel carrying a device to reader (D2R) message transmitted on each access occasion in the first set is different from a maximum transmission duration of a physical channel carrying a D2R message transmitted on each access occasion in the second set. (Supplementary Note 25) The reader according to any one of Supplements 15 to 24, wherein the R2D message initiates one paging round including multiple access occasions. (Supplementary Note 26) The reader according to any one of Supplements 15 to 25, wherein the R2D message is a paging message or an initial trigger message sent by the reader. (Supplementary Note 27) A method performed by a reader, comprising: sending a reader to device (R2D) message used to trigger or cause random access by one or more Ambient Internet of Things (AIoT) devices and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed, wherein the R2D message causes the AIoT devices to decide whether to perform one or both of the first type of random access procedure and the second type of random access procedure.(Supplementary Note 28) A program causing a computer to perform a method for a reader, the method comprising sending a reader to device (R2D) message used to trigger or cause random access by one or more Ambient Internet of Things (AIoT) devices and specifying one or both of a first type random access procedure and a second type random access procedure as allowed, the R2D message causing the AIoT device to decide whether to perform one or both of the first type random access procedure and the second type random access procedure. (Supplementary Note 29) An Ambient Internet of Things (AIoT) device comprising: means for receiving a reader to device (R2D) message; means for autonomously deciding whether to perform one of the first type random access procedure and the second type random access procedure; and means for communicating with a reader according to the determined random access procedure in one or more of a plurality of access occasions in a paging round initiated by the R2D message. (Supplementary Note 30) The AIoT device according to Supplementary Note 29, wherein the communicating means is configured to, when transmitting a first message for random access in an access occasion, include an indication of the determined random access procedure in the first message, a Protocol Data Unit (PDU) containing the first message, or a physical channel carrying the first message. (Supplementary Note 31) The AIoT device according to Supplementary Note 30, wherein the communicating means is configured to include or add a predetermined end marker or postamble at the end of the first message, the end of the PDU, or the end of the physical channel.(Supplementary Note 32) The AIoT device of Supplementary Note 29, wherein the communicating means is configured to include or add a predetermined end marker or postamble to the end of the first message, the end of a Protocol Data Unit (PDU) containing the first message, or the end of a physical channel carrying the first message, when transmitting a first message of random access in an access occasion. (Supplementary Note 33) The AIoT device of any one of Supplements 29 to 32, wherein the determining means is configured to determine whether to use the first type of random access procedure or the second type of random access procedure based on a size of data to be transmitted in the access occasion. (Supplementary Note 34) A method performed by an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message; autonomously determining whether to perform the first type of random access procedure or the second type of random access procedure; and communicating with a reader according to the determined random access procedure in one or more access occasions in a paging round initiated by the R2D message. (Supplementary Note 35) A program for causing a computer to perform a method for an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message; autonomously determining whether to perform a first type random access procedure or a second type random access procedure; and communicating with a reader according to the determined random access procedure in one or more of multiple access occasions within a single paging round initiated by the R2D message.(Supplementary Note 36) An Ambient Internet of Things (AIoT) device comprising: means for attempting to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, if a second trigger message is used in the inventory procedure, or for attempting to receive a second message in a two-step-like random access procedure performed at the access occasion. (Supplementary Note 37) The AIoT device of Supplementary Note 36, further comprising means for understanding that the fourth message will not be transmitted in the four-step-like random access procedure performed at the access occasion, or for understanding that the second message will not be transmitted in the two-step-like random access procedure performed at the access occasion, if the second trigger message is not used in the inventory procedure. (Supplementary Note 38) The AIoT device of Supplementary Note 36 or 37, wherein the initial trigger message includes an indication of whether the second trigger message will be used. (Supplementary Note 39) The AIoT device of Supplementary Note 38, further comprising: means for determining that reception of the fourth message in the four-step-like random access procedure or the second message in the two-step-like random access procedure is necessary or expected, based on the indication that the second trigger message will be used. (Supplementary Note 40) The AIoT device of any one of Supplements 36 to 39, wherein the second trigger message triggers an additional paging round, and the second trigger message causes devices that failed to receive the fourth message or the second message in any access occasion within the paging round started by the initial trigger message to transmit in the additional paging round.(Supplementary Note 41) A method performed by an Ambient Internet of Things (AIoT) device, comprising, if a second trigger message is used in the inventory procedure, attempting to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, or attempting to receive a second message in a two-step-like random access procedure performed at the access occasion. (Supplementary Note 42) A program for causing a computer to perform a method for an Ambient Internet of Things (AIoT) device, comprising, if a second trigger message is used in the inventory procedure, attempting to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, or attempting to receive a second message in a two-step-like random access procedure performed at the access occasion. (Supplementary Note 43) An Ambient Internet of Things (AIoT) device comprising: means for receiving a reader to device (R2D) message that specifies a first parameter for defining the number of multiple access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure transmitted in the paging round; means for selecting access occasions the same number as the number of replicas using the first parameter and the second parameter; and means for attempting to transmit two or more replicas of the first message to a reader in the two or more selected access occasions.(Supplementary Note 44) The AIoT device according to Supplementary Note 43, further comprising means for canceling replica transmissions in one or more remaining access occasions of the selected two or more access occasions if a second message of the two-step-like random access procedure is received in one of the selected two or more access occasions and if the second message indicates that the first message has been successfully received. (Supplementary Note 45) The AIoT device according to Supplementary Note 43 or 44, wherein the R2D message initiates the paging round including the multiple access occasions. (Supplementary Note 46) The AIoT device according to any one of Supplements 43 to 45, wherein the R2D message is a paging message or an initial trigger message sent by the reader. (Supplementary Note 47) A method performed by an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message specifying a first parameter for defining the number of multiple access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round; selecting access occasions equal in number to the number of replicas using the first parameter and the second parameter; and attempting to transmit two or more replicas of the first message to a reader in the selected two or more access occasions.(Supplementary Note 48) A program for causing a computer to perform a method for an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message specifying a first parameter for defining the number of multiple access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round; selecting access occasions equal in number to the number of replicas using the first parameter and the second parameter; and attempting to transmit two or more replicas of the first message to a reader in the two or more selected access occasions. (Supplementary Note 49) A reader comprising: means for transmitting a reader to device (R2D) message specifying a first parameter for defining the number of multiple access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round, wherein the R2D message causes one or more Ambient Internet of Things (AIoT) devices to select access occasions equal to the number of replicas using the first parameter and the second parameter, and to attempt to transmit two or more replicas of the first message in the selected two or more access occasions. (Supplementary Note 50) A reader as described in Supplementary Note 49, wherein if the first message from an AIoT device is successfully received in an access occasion, a second message of the two-step-like random access procedure is sent to the AIoT device, the second message indicating that the first message has been successfully received, and the second message causes the AIoT device to cancel replica transmissions in one or more remaining access occasions of the selected two or more access occasions.(Supplementary Note 51) The reader according to Supplementary Note 49 or 50, wherein the R2D message initiates the paging round including the plurality of access occasions. (Supplementary Note 52) The reader according to any one of Supplements 49 to 51, wherein the R2D message is a paging message or an initial trigger message. (Supplementary Note 53) A method performed by a reader, comprising: transmitting a reader to device (R2D) message specifying a first parameter for defining the number of plurality of access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round, wherein the R2D message selects access occasions equal to the number of replicas using the first parameter and the second parameter, and causes one or more Ambient Internet of Things (AIoT) devices to attempt to transmit two or more replicas of the first message in the selected two or more access occasions. (Supplementary Note 54) A program that causes a computer to perform a method for a reader, comprising transmitting a reader to device (R2D) message that specifies a first parameter for defining the number of multiple access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round, wherein the R2D message causes one or more Ambient Internet of Things (AIoT) devices to select access occasions equal to the number of replicas using the first parameter and the second parameter, and to attempt to transmit two or more replicas of the first message in the selected two or more access occasions.

[0177] This application claims priority based on Japanese Patent Application No. 2024-129700, filed August 6, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0178] 1 AIoT device 2 Base station 3 Radio access network 4 Core network 5 Intermediate node 6 Assist node 8 Reader 2104 Controller 2105 Memory 2204 Processor 2205 Memory 2206 Modules 2303 Baseband processor 2304 Application processor 2306 Memory 2307 Modules

Claims

1. An Ambient Internet of Things (AIoT) device comprising: means for receiving a reader to device (R2D) message used to trigger or cause random access by one or more AIoT devices and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed; and means for determining whether to perform one or both of the first type of random access procedure and the second type of random access procedure based on the R2D message.

2. The AIoT device of claim 1, wherein the first type random access procedure is a four-step-like random access procedure, and the second type random access procedure is a two-step-like random access procedure.

3. The AIoT device of claim 1 or 2, wherein the R2D message indicates whether the first type random access procedure, the second type random access procedure, or both the first type and the second type random access procedures are allowed.

4. The AIoT device according to any one of claims 1 to 3, wherein the determining means is configured to determine, based on the R2D message, whether to perform the first type random access procedure, the second type random access procedure, or neither the first type random access procedure nor the second type random access procedure.

5. The AIoT device according to any one of claims 1 to 4, wherein the determining means is configured to determine, based on the R2D message, whether to perform one or both of the first type random access procedure and the second type random access procedure in one or more of a plurality of access occasions within one paging round initiated by the R2D message.

6. The AIoT device of any one of claims 1 to 5, further comprising: means for ignoring the R2D message if the R2D message indicates that the first type of random access procedure is allowed but the second type of random access procedure is not allowed, and if the determining means determines to perform the second type of random access procedure.

7. The AIoT device of any one of claims 1 to 5, further comprising: means for ignoring the R2D message if the R2D message indicates that the first type of random access procedure is allowed but the second type of random access procedure is not allowed, and if the AIoT device is not configured for or does not support the first type of random access procedure.

8. The AIoT device of any one of claims 1 to 7, wherein, when the R2D message indicates that both the first type and the second type of random access procedure are allowed, the R2D message includes one or more parameters for defining a first set of access occasions for the first type of random access procedure and a second set of access occasions for the second type of random access procedure separated from the first set.

9. The AIoT device of claim 8, wherein a maximum size of a device to reader (D2R) message sent at each access occasion in the first set is different from a maximum size of a D2R message sent at each access occasion in the second set.

10. The AIoT device of claim 8, wherein a maximum transmission duration of a physical channel carrying a device to reader (D2R) message transmitted at each access occasion in the first set is different from a maximum transmission duration of a physical channel carrying a D2R message transmitted at each access occasion in the second set.

11. The AIoT device of any one of claims 1 to 10, wherein the R2D message initiates a single paging round that includes multiple access occasions.

12. The AIoT device described in any one of claims 1 to 11, wherein the R2D message is a paging message or an initial trigger message sent by a reader.

13. A method performed by one or more Ambient Internet of Things (AIoT) devices, comprising: receiving a reader to device (R2D) message used to trigger or cause random access by an AIoT device and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed; and determining whether to perform one or both of the first type of random access procedure and the second type of random access procedure based on the R2D message.

14. A program for causing a computer to perform a method for one or more Ambient Internet of Things (AIoT) devices, comprising: receiving a reader to device (R2D) message used to trigger or cause random access by an AIoT device and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed; and determining whether to perform one or both of the first type of random access procedure and the second type of random access procedure based on the R2D message.

15. A reader, comprising means for transmitting a reader to device (R2D) message used to trigger or cause random access by one or more Ambient Internet of Things (AIoT) devices and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed, wherein the R2D message causes the AIoT device to decide whether to perform one or both of the first type of random access procedure and the second type of random access procedure.

16. The reader according to claim 15, wherein the first type of random access procedure is a four-step-like random access procedure, and the second type of random access procedure is a two-step-like random access procedure.

17. The reader of claim 15 or 16, wherein the R2D message indicates whether the first type of random access procedure, the second type of random access procedure, or both the first type and the second type of random access procedure are allowed.

18. The reader of any one of claims 15 to 17, wherein the R2D message causes the AIoT device to decide whether to perform the first type random access procedure, the second type random access procedure, or neither the first type random access procedure nor the second type random access procedure.

19. The reader of any one of claims 15 to 18, wherein the R2D message causes the AIoT device to decide whether to perform one or both of the first type random access procedure and the second type random access procedure in one or more of multiple access occasions within a paging round initiated by the R2D message.

20. The reader of any one of claims 15 to 19, wherein if the R2D message indicates that the first type of random access procedure is allowed but the second type of random access procedure is not allowed, and if the AIoT device decides to perform the second type of random access procedure, the R2D message causes the AIoT device to ignore the R2D message.

21. The reader of any one of claims 15 to 19, wherein if the R2D message indicates that the first type of random access procedure is allowed but the second type of random access procedure is not allowed, and if the AIoT device is not configured or does not support the first type of random access procedure, the R2D message causes the AIoT device to ignore the R2D message.

22. A reader according to any one of claims 15 to 21, wherein if the R2D message indicates that both the first type and the second type of random access procedure are allowed, the R2D message includes one or more parameters for defining a first set of access occasions for the first type of random access procedure and a second set of access occasions for the second type of random access procedure separated from the first set.

23. The reader of claim 22, wherein a maximum size of a device to reader (D2R) message sent at each access occasion in the first set is different from a maximum size of a D2R message sent at each access occasion in the second set.

24. The reader of claim 22, wherein a maximum transmission duration of a physical channel carrying a device to reader (D2R) message sent at each access occasion in the first set is different from a maximum transmission duration of a physical channel carrying a D2R message sent at each access occasion in the second set.

25. The reader of any one of claims 15 to 24, wherein the R2D message initiates a single paging round that includes multiple access occasions.

26. The reader of any one of claims 15 to 25, wherein the R2D message is a paging message or an initial trigger message sent by the reader.

27. A method performed by a reader, comprising: sending a reader to device (R2D) message used to trigger or cause random access by one or more Ambient Internet of Things (AIoT) devices and specifying one or both of a first type of random access procedure and a second type of random access procedure that are allowed, wherein the R2D message causes the AIoT device to decide whether to perform one or both of the first type of random access procedure and the second type of random access procedure.

28. A program that causes a computer to perform a method for a reader, the method comprising sending a reader to device (R2D) message that is used to trigger or cause random access by one or more Ambient Internet of Things (AIoT) devices and that specifies one or both of a first type of random access procedure and a second type of random access procedure that are allowed, the R2D message causing the AIoT device to determine whether to perform one or both of the first type of random access procedure and the second type of random access procedure.

29. An Ambient Internet of Things (AIoT) device comprising: means for receiving a reader to device (R2D) message; means for autonomously determining whether to perform a first type random access procedure or a second type random access procedure; and means for communicating with a reader according to the determined random access procedure at one or more of a plurality of access occasions within a paging round initiated by the R2D message.

30. The AIoT device of claim 29, wherein the communicating means is configured to, when transmitting a first message for random access in an access occasion, include an indication of the determined random access procedure in the first message, a Protocol Data Unit (PDU) containing the first message, or a physical channel carrying the first message.

31. The AIoT device of claim 30, wherein the means for communicating is configured to include or add a predetermined end marker or postamble at the end of the first message, the end of the PDU, or the end of the physical channel.

32. The AIoT device of claim 29, wherein the communicating means is configured to, when transmitting a first random access message in an access occasion, include or add a predetermined end marker or postamble at the end of the first message, at the end of a Protocol Data Unit (PDU) containing the first message, or at the end of a physical channel carrying the first message.

33. The AIoT device of any one of claims 29 to 32, wherein the determining means is configured to determine whether to use the first type of random access procedure or the second type of random access procedure based on the size of data to be transmitted in an access occasion.

34. A method performed by an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message; autonomously determining whether to perform a first type random access procedure or a second type random access procedure; and communicating with a reader according to the determined random access procedure in one or more of a plurality of access occasions within a paging round initiated by the R2D message.

35. A program for causing a computer to perform a method for an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message; autonomously determining whether to perform a first type random access procedure or a second type random access procedure; and communicating with a reader according to the determined random access procedure in one or more of multiple access occasions within a paging round initiated by the R2D message.

36. An Ambient Internet of Things (AIoT) device comprising means for attempting to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, if a second trigger message is used in the inventory procedure, or for attempting to receive a second message in a two-step-like random access procedure performed at the access occasion.

37. The AIoT device of claim 36, further comprising means for understanding that if the second trigger message is not used in the inventory procedure, the fourth message will not be transmitted in the four-step-like random access procedure performed in the access occasion, or for understanding that the second message will not be transmitted in the two-step-like random access procedure performed in the access occasion.

38. The AIoT device of claim 36 or 37, wherein the initial trigger message includes an indication of whether the second trigger message will be used.

39. The AIoT device of claim 38, further comprising: means for determining that reception of the fourth message in the four-step-like random access procedure or reception of the second message in the two-step-like random access procedure is necessary or expected based on the indication that the second trigger message will be used.

40. The AIoT device described in any one of claims 36 to 39, wherein the second trigger message triggers an additional paging round, and the second trigger message causes devices that failed to receive the fourth message or the second message in any access occasion within the paging round initiated by the initial trigger message to transmit in the additional paging round.

41. A method performed by an Ambient Internet of Things (AIoT) device, comprising, if a second trigger message is used in an inventory procedure, attempting to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, or attempting to receive a second message in a two-step-like random access procedure performed at the access occasion.

42. A program for causing a computer to perform a method for an Ambient Internet of Things (AIoT) device, comprising, if a second trigger message is used in the inventory procedure, attempting to receive a fourth message in a four-step-like random access procedure performed at an access occasion within a paging round initiated by an initial trigger message for the inventory procedure, or attempting to receive a second message in a two-step-like random access procedure performed at the access occasion.

43. An Ambient Internet of Things (AIoT) device comprising: means for receiving a reader to device (R2D) message that specifies a first parameter for defining the number of multiple access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round; means for selecting access occasions whose number is equal to the number of replicas using the first parameter and the second parameter; and means for attempting to transmit two or more replicas of the first message to a reader in the two or more selected access occasions.

44. The AIoT device of claim 43, further comprising means for canceling replica transmissions in one or more remaining access occasions of the selected two or more access occasions if a second message of the two-step-like random access procedure is received in one of the selected two or more access occasions and if the second message indicates that the first message has been successfully received.

45. The AIoT device of claim 43 or 44, wherein the R2D message initiates the paging round including the multiple access occasions.

46. ​​The AIoT device described in any one of claims 43 to 45, wherein the R2D message is a paging message or an initial trigger message sent by the reader.

47. A method performed by an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message specifying a first parameter for defining the number of access occasions in a paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round; selecting access occasions equal in number to the number of replicas using the first parameter and the second parameter; and attempting to transmit two or more replicas of the first message to a reader in the two or more selected access occasions.

48. A program for causing a computer to perform a method for an Ambient Internet of Things (AIoT) device, comprising: receiving a reader to device (R2D) message specifying a first parameter for defining the number of access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round; selecting access occasions equal in number to the number of replicas using the first parameter and the second parameter; and attempting to transmit two or more replicas of the first message to a reader in the two or more selected access occasions.

49. A reader, comprising: means for transmitting a reader to device (R2D) message specifying a first parameter for defining the number of access occasions in one paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round, wherein the R2D message causes one or more Ambient Internet of Things (AIoT) devices to select a number of access occasions equal to the number of replicas using the first parameter and the second parameter and attempt to transmit two or more replicas of the first message in the two or more selected access occasions.

50. The reader of claim 49, wherein upon successfully receiving the first message from an AIoT device in an access occasion, a second message of the two-step-like random access procedure is sent to the AIoT device, the second message indicating that the first message has been successfully received, and the second message causes the AIoT device to cancel replica transmissions in one or more remaining access occasions of the selected two or more access occasions.

51. The reader of claim 49 or 50, wherein the R2D message initiates the paging round including the multiple access occasions.

52. A reader as claimed in any one of claims 49 to 51, wherein the R2D message is a paging message or an initial trigger message.

53. A method performed by a reader, comprising: transmitting a reader to device (R2D) message specifying a first parameter for defining the number of access occasions in a paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round; wherein the R2D message causes one or more Ambient Internet of Things (AIoT) devices to select a number of access occasions equal to the number of replicas using the first parameter and the second parameter, and to attempt to transmit two or more replicas of the first message in the two or more selected access occasions.

54. A program that causes a computer to perform a method for a reader, comprising transmitting a reader to device (R2D) message that specifies a first parameter for defining the number of access occasions in a paging round and a second parameter for defining the number of two or more replicas of a first message of a two-step-like random access procedure to be transmitted in the paging round, wherein the R2D message causes one or more Ambient Internet of Things (AIoT) devices to select a number of access occasions equal to the number of replicas using the first parameter and the second parameter, and to attempt to transmit two or more replicas of the first message in the two or more selected access occasions.

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