Method and apparatus for performing random access procedure

Abstract

The present embodiments provide a method in which an ambient IoT terminal performs a random access procedure, the method comprising the steps of: receiving, from a reader device, resource information for transmission of a first message, monitoring window configuration information for each terminal, and information indicating a maximum monitoring count; transmitting the first message through a time domain resource selected from among time domain resources included in the resource information; monitoring a second message, a retransmitted second message, or a third message feedback within a periodic on / off type monitoring window determined on the basis of the selected time domain resource and offset information included in the monitoring window configuration information; and transmitting a subsequent message to the reader device on the basis of a reception result according to the monitoring.

Description

Method and device for performing a random access procedure

[0001] The embodiments propose a method and apparatus for performing a random access procedure in a next-generation wireless access network (in this disclosure, "5G", "NR [New Radio]", "5G-Advanced", "6G" or subsequent 3GPP wireless access networks).

[0002] In recent years, the Internet of Things (IoT) has attracted significant attention in the field of wireless communication. It is expected that an increasing number of objects will become interconnected to improve productivity efficiency and enhance the comfort of daily life. Further reducing the size, complexity, and power consumption of IoT devices enables the deployment of tens or even hundreds of billions of IoT devices for various applications, thereby providing added value across the entire value chain. However, it is impossible to power all IoT devices with batteries, and since batteries must be manually replaced or recharged, this can lead to high maintenance costs, serious environmental issues, and even safety risks for some use cases.

[0003] In this regard, efficient power consumption of IoT devices is required, and accordingly, there is a need for specific designs regarding methods to manage the energy of IoT devices more efficiently.

[0004] Embodiments of the present disclosure may provide a method and apparatus for performing a random access procedure in an Ambient IoT (hereinafter also referred to as A-IoT) environment.

[0005] In one aspect, the present embodiments may provide a method for an Ambient IoT terminal to perform a random access procedure, comprising the steps of: receiving resource information for transmitting a first message (Msg1), terminal-specific monitoring window configuration information, and maximum monitoring count information from a reader device; transmitting the first message through a selected time domain resource among the time domain resources included in the resource information; monitoring a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the selected time domain resource and offset information included in the monitoring window configuration information; and transmitting a subsequent message to the reader device based on the received result of the monitoring.

[0006] In another aspect, the present embodiments may provide a method for a reader device to perform a random access procedure, comprising the steps of: transmitting resource information for transmitting a first message (Msg1) to an Ambient IoT terminal, terminal-specific monitoring window configuration information, and maximum monitoring count information; receiving the first message through a selected time domain resource among the time domain resources included in the resource information; transmitting a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the selected specific time domain resource and offset information included in the monitoring window configuration information; and receiving a subsequent message from the Ambient IoT terminal.

[0007] In another aspect, the present embodiments provide an Ambient IoT terminal that performs a random access procedure, comprising a transmitter, a receiver, and a control unit that controls the operation of the transmitter and the receiver. The control unit receives resource information for transmitting a first message (Msg1), terminal-specific monitoring window configuration information, and maximum monitoring count information from a reader device, transmits the first message through a selected time domain resource among the time domain resources included in the resource information, monitors a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a monitoring window in the form of a periodic ON / OFF determined based on the selected time domain resource and offset information included in the monitoring window configuration information, and transmits a subsequent message to the reader device based on the reception result according to the monitoring.

[0008] In another aspect, the embodiments may provide a reader device for performing a random access procedure, comprising a transmitter, a receiver, and a control unit for controlling the operation of the transmitter and the receiver. The control unit transmits resource information for transmitting a first message (Msg1) to an Ambient IoT terminal, monitoring window configuration information per terminal, and information on the maximum number of monitoring cycles; receives the first message through a selected time domain resource among the time domain resources included in the resource information; transmits a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a monitoring window in the form of a periodic ON / OFF determined based on the selected specific time domain resource and offset information included in the monitoring window configuration information; and receives a subsequent message from the Ambient IoT terminal.

[0009] According to the embodiments, a method and apparatus for performing a random access procedure in an ambient IoT environment can be provided.

[0010] In addition, energy-efficient random access procedures can be performed with minimal power consumption through ON / OFF-based periodic monitoring operations.

[0011] FIG. 1 is a diagram briefly illustrating the structure of an NR wireless communication system to which the present embodiment can be applied.

[0012] FIG. 2 is a drawing illustrating the frame structure in an NR system to which the present embodiment can be applied.

[0013] FIG. 3 is a diagram illustrating a resource grid supported by wireless access technology to which the present embodiment can be applied.

[0014] FIG. 4 is a diagram illustrating the bandwidth part supported by the wireless access technology to which the present embodiment can be applied.

[0015] FIG. 5 is a diagram illustrating an exemplary synchronization signal block in a wireless access technology to which the present embodiment can be applied.

[0016] FIG. 6 is a diagram illustrating a random access procedure in a wireless access technology to which the present embodiment can be applied.

[0017] Figure 7 is a diagram for explaining CORESET.

[0018] FIG. 8 is a diagram illustrating the Reader / Tag operations and tag state of RFID.

[0019] FIGS. 9 and FIGS. 10 are drawings illustrating a connectivity topology for an A-IoT network and device to which the present embodiment can be applied.

[0020] FIG. 11 is a diagram illustrating the procedure of the Access Stratum (AS) layer between an A-IoT terminal and a reader according to one embodiment.

[0021] FIG. 12 is a diagram illustrating a wireless interface protocol stack between an A-IoT terminal and a reader according to one embodiment.

[0022] FIG. 13 is a diagram illustrating a 3-step CBRA procedure according to one embodiment.

[0023] FIG. 14 is a diagram illustrating a CFRA procedure according to one embodiment.

[0024] FIG. 15 is a diagram illustrating R2D transmission corresponding to D2R of an FDMA-based D2R and multiple A-IoT terminals according to one embodiment.

[0025] FIG. 16 is a diagram illustrating an R2D transmission corresponding to D2R of a single A-IoT terminal and an FDMA-based D2R according to one embodiment.

[0026] FIG. 17 is a diagram illustrating an R2D transmission corresponding to D2R of a single A-IoT terminal and an FDMA-based D2R according to another embodiment.

[0027] FIG. 18 is a diagram illustrating R2D transmission corresponding to D2R of a TDMA-based D2R and multiple A-IoT terminals according to one embodiment.

[0028] FIG. 19 is a diagram illustrating R2D transmission corresponding to D2R of a single A-IoT terminal and a TDMA-based D2R according to one embodiment.

[0029] FIG. 20 is a diagram illustrating the absence of a subsequent operation following the failure to receive Msg2 of an A-IoT terminal according to one embodiment.

[0030] FIG. 21 is a diagram illustrating a procedure for an A-IoT terminal to perform random access according to one embodiment.

[0031] FIG. 22 is a diagram illustrating a procedure for a reader device to perform random access according to one embodiment.

[0032] FIG. 23 is a diagram illustrating the configuration of multiple monitoring windows according to one embodiment.

[0033] FIG. 24 is a diagram illustrating a monitoring window-based (re-)Msg2 / Msg3 feedback operation according to one embodiment.

[0034] FIG. 25 is a diagram showing the configuration of a terminal according to another embodiment.

[0035] FIG. 26 is a drawing showing the configuration of a reader device according to another embodiment.

[0036] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the exemplary drawings. In assigning reference numerals to the components of each drawing, the same components may have the same reference numeral as much as possible, even if they are shown in different drawings. Furthermore, in describing the embodiments, if it is determined that a detailed description of related known components or functions may obscure the essence of the technical concept, such detailed description may be omitted. Where terms such as "comprising," "having," or "consisting of" are used in this specification, other parts may be added unless "only" is used. Where a component is expressed in the singular, it may include a plural unless otherwise specified.

[0037] Additionally, terms such as first, second, A, B, (a), (b), etc., may be used to describe the components of the present disclosure. These terms are used merely to distinguish the components from other components, and the nature, order, sequence, or number of the components are not limited by such terms.

[0038] In describing the positional relationship of components, where it is stated that two or more components are "connected," "combined," or "joined," it should be understood that while the two or more components may be directly "connected," "combined," or "joined," they may also be "connected," "combined," or "joined" with other components "intervened." Here, the other components may be included in one or more of the two or more components that are "connected," "combined," or "joined" with one another.

[0039] In describing the temporal flow relationship regarding components, methods of operation, or methods of production, for example, when the temporal or sequential relationship is described using "after," "following," "next," or "before," it may include cases where the relationship is not continuous unless "immediately" or "directly" is used.

[0040] Meanwhile, where numerical values ​​or corresponding information regarding a component (e.g., levels, etc.) are mentioned, even without separate explicit notation, the numerical values ​​or corresponding information may be interpreted as including a range of error that may occur due to various factors (e.g., process factors, internal or external shocks, noise, etc.).

[0041] A wireless communication system in this specification refers to a system for providing various communication services, such as voice and data packets, using wireless resources, and may include a terminal, a base station, or a core network.

[0042] The embodiments disclosed below may be applied to wireless communication systems using various wireless access technologies. For example, the embodiments may be applied to various wireless access technologies such as CDMA (code division multiple access), FDMA (frequency division multiple access), TDMA (time division multiple access), OFDMA (orthogonal frequency division multiple access), SC-FDMA (single carrier frequency division multiple access), or NOMA (non-orthogonal multiple access). Furthermore, wireless access technology may refer not only to specific access technologies but also to communication technologies for each generation established by various telecommunication organizations such as 3GPP, 3GPP2, WiFi, Bluetooth, IEEE, and ITU. For example, CDMA may be implemented as a wireless technology such as UTRA (universal terrestrial radio access) or CDMA2000. TDMA may be implemented as a wireless technology such as GSM (global system for mobile communications), GPRS (general packet radio service), or EDGE (enhanced datarates for GSM evolution). OFDMA can be implemented using wireless technologies such as IEEE (Institute of Electrical and Electronic Engineers) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, and E-UTRA (evolved UTRA). IEEE 802.16m is an evolution of IEEE 802.16e and provides backward compatibility with systems based on IEEE 802.16e.UTRA is part of UMTS (universal mobile telecommunications system). 3GPP (3rd generation partnership project) LTE (long term evolution) is part of E-UMTS (evolved UMTS) that uses E-UTRA (evolved-UMTS terrestrial radio access), employing OFDMA in the downlink and SC-FDMA in the uplink. As such, these embodiments can be applied to currently disclosed or commercialized radio access technologies, and can also be applied to radio access technologies currently under development or to be developed in the future.

[0043] Meanwhile, the term "terminal" in this specification is a comprehensive concept meaning a device including a wireless communication module that communicates with a base station in a wireless communication system. It should be interpreted as a concept that includes not only User Equipment (UE) in WCDMA, LTE, NR, HSPA, and IMT-2020 (5G or New Radio), but also Mobile Station (MS), User Terminal (UT), Subscriber Station (SS), and wireless device in GSM. Furthermore, depending on the usage type, the terminal may be a user portable device such as a smartphone, or in a V2X communication system, it may refer to a vehicle or a device including a wireless communication module inside a vehicle. Additionally, in the case of a Machine Type Communication (MMC) system, it may refer to an MTC terminal, M2M terminal, URLLC terminal, etc., equipped with a communication module to perform machine type communication.

[0044] In this specification, "base station" or "cell" refers to an end that communicates with a terminal in terms of a network, and encompasses various coverage areas such as Node-B, eNB (evolved Node-B), gNB (gNode-B), LPN (Low Power Node), Sector, Site, various types of antennas, BTS (Base Transceiver System), Access Point, Point (e.g., Transmitter Point, Receiver Point, Transceiver Point), Relay Node, Mega Cell, Macro Cell, Micro Cell, Pico Cell, Femto Cell, RRH (Remote Radio Head), RU (Radio Unit), and Small Cell. Additionally, "cell" may include a Bandwidth Part (BWP) in the frequency domain. For example, a serving cell may refer to the Activation BWP of a terminal.

[0045] Since there is a base station controlling one or more of the various cells listed above, the term "base station" can be interpreted in two senses. 1) It may refer to the device itself that provides a mega cell, macro cell, micro cell, pico cell, femto cell, or small cell in relation to a wireless area, or 2) it may refer to the wireless area itself. In 1), all devices that provide a specific wireless area are controlled by the same entity or interact to configure the wireless area collaboratively are referred to as base stations. Depending on the configuration method of the wireless area, a point, a transmitting / receiving point, a transmitting point, a receiving point, etc., are examples of a base station. In 2), the wireless area itself that receives or transmits a signal from the perspective of a user terminal or from the perspective of a neighboring base station may also be referred to as a base station.

[0046] In this specification, "Cell" may refer to a component carrier having coverage of a signal transmitted from a transmitting / receiving point or coverage of a signal transmitted from a transmitting / receiving point (transmission point or transmission / reception point), or the transmitting / receiving point itself.

[0047] Uplink (UL, or Uplink) refers to the method of transmitting and receiving data from a terminal to a base station, and Downlink (DL, or Downlink) refers to the method of transmitting and receiving data from a base station to a terminal. Downlink may refer to communication or a communication path from multiple transmission and reception points to a terminal, and uplink may refer to communication or a communication path from a terminal to multiple transmission and reception points. In this case, in the downlink, the transmitter may be part of the multiple transmission and reception points, and the receiver may be part of the terminal. Additionally, in the uplink, the transmitter may be part of the terminal, and the receiver may be part of the multiple transmission and reception points.

[0048] The uplink and downlink transmit and receive control information through control channels such as PDCCH (Physical Downlink Control Channel) and PUCCH (Physical Uplink Control Channel), and transmit and receive data by configuring data channels such as PDSCH (Physical Downlink Shared Channel) and PUSCH (Physical Uplink Shared Channel). In the following description, the situation in which signals are transmitted and received through channels such as PUCCH, PUSCH, PDCCH, and PDSCH is also referred to as "transmitting and receiving PUCCH, PUSCH, PDCCH, and PDSCH."

[0049] To clarify the explanation, the technical concept described below is primarily based on 3GPP LTE / LTE-A / NR (New RAT) communication systems, but the technical features are not limited to said communication systems.

[0050] Following research on 4G (4th-Generation) communication technology, 3GPP develops 5G (5th-Generation) communication technology to meet the requirements of the ITU-R for next-generation radio access technology. Specifically, 3GPP develops LTE-A pro, which enhances LTE-Advanced technology to meet ITU-R requirements, and NR, a new communication technology distinct from 4G communication technology, as 5G communication technologies. Since both LTE-A pro and NR refer to 5G communication technology, the following description of 5G communication technology will focus on NR unless a specific technology is being identified.

[0051] The operational scenarios in NR define various operation scenarios by adding considerations for satellites, automobiles, and new verticals to the existing 4G LTE scenarios, and in terms of service, they support eMBB (Enhanced Mobile Broadband) scenarios, mMTC (Massive Machine Communication) scenarios which require low data rates and asynchronous access while having high terminal density and being deployed over a wide range, and URLLC (Ultra Reliability and Low Latency) scenarios which require high responsiveness and reliability and can support high-speed mobility.

[0052] To satisfy these scenarios, NR introduces a wireless communication system equipped with new waveform and frame structure technologies, low latency technology, mmWave support technology, and forward compatibility technology. In particular, the NR system presents various technical changes in terms of flexibility to provide forward compatibility. The main technical features of NR are explained below with reference to the drawings.

[0053]

[0054] <NR 시스템 일반>

[0055] FIG. 1 is a simplified diagram illustrating the structure of an NR system to which the present embodiment can be applied.

[0056] Referring to FIG. 1, the NR system is divided into a 5G Core Network (5GC) and an NR-RAN part. The NG-RAN consists of gNBs and ng-eNBs that provide control plane (RRC) protocol endpoints for the user plane (SDAP / PDCP / RLC / MAC / PHY) and User Equipment (UE). gNBs are interconnected with each other, or gNBs and ng-eNBs are interconnected via Xn interfaces. Each gNB and ng-eNB is connected to the 5GC via an NG interface. The 5GC may be configured to include an Access and Mobility Management Function (AMF), which is responsible for control plane functions such as terminal access and mobility control, and a User Plane Function (UPF), which is responsible for control functions for user data. The NR system includes support for both frequency bands below 6 GHz (FR1, Frequency Range 1) and frequency bands above 6 GHz (FR2, Frequency Range 2).

[0057] gNB refers to a base station that provides NR user plane and control plane protocol terminations to a terminal, and ng-eNB refers to a base station that provides E-UTRA user plane and control plane protocol terminations to a terminal. The base station described in this specification should be understood as encompassing both gNB and ng-eNB, and may also be used to refer to gNB or ng-eNB separately as necessary.

[0058] <NR 웨이브 폼, 뉴머롤러지 및 프레임 구조>

[0059]

[0060] In NR, CP-OFDM waveforms using a cyclic prefix are used for downlink transmission, and CP-OFDM or DFT-s-OFDM are used for uplink transmission. OFDM technology is easy to combine with MIMO (Multiple Input Multiple Output) and has the advantage of allowing the use of low-complexity receivers along with high frequency efficiency.

[0061] Meanwhile, in NR, since the requirements for data rate, latency, coverage, etc. differ for each of the three scenarios mentioned above, it is necessary to efficiently satisfy the requirements for each scenario through the frequency bands that constitute an arbitrary NR system. To this end, a technology has been proposed to efficiently multiplex wireless resources based on multiple different numerologies.

[0062] Specifically, the NR transmission numerator is determined based on sub-carrier spacing and CP (Cyclic prefix), and as shown in Table 1 below, the μ value is used as an exponential value of 2 based on 15 kHz and changes exponentially.

[0063] μ서브캐리어 간격Cyclic prefixSupported for dataSupported for synch015NormalYesYes130NormalYesYes260Normal, ExtendedYesNo3120NormalYesYes4240NormalNoYes

[0064] As shown in Table 1 above, the numerators of NR can be classified into five types based on the subcarrier spacing. This differs from LTE, one of the 4G communication technologies, where the subcarrier spacing is fixed at 15 kHz. Specifically, the subcarrier spacings used for data transmission in NR are 15, 30, 60, and 120 kHz, while the subcarrier spacings used for synchronization signal transmission are 15, 30, 12, and 240 kHz. Additionally, extended CP applies only to the 60 kHz subcarrier spacing. Meanwhile, the frame structure in NR defines a frame with a length of 10ms, composed of 10 subframes of equal length of 1ms. A single frame can be divided into 5ms half-frames, and each half-frame contains 5 subframes. In the case of a 15 kHz subcarrier interval, one subframe consists of one slot, and each slot consists of 14 OFDM symbols. FIG. 2 is a diagram illustrating the frame structure in an NR system to which the present embodiment can be applied. Referring to FIG. 2, in the case of a normal CP, the slot is fixedly composed of 14 OFDM symbols, but the length of the slot in the time domain may vary depending on the subcarrier interval. For example, in the case of a numeral with a 15 kHz subcarrier interval, the slot is composed of a length of 1 ms, which is the same length as the subframe. In contrast, in the case of a numeral with a 30 kHz subcarrier interval, the slot is composed of 14 OFDM symbols, but two slots may be included in one subframe with a length of 0.5 ms. That is, the subframe and the frame are defined with a fixed time length, while the slot is defined by the number of symbols, and the time length may vary depending on the subcarrier interval.

[0065] Meanwhile, NR defines the basic unit of scheduling as a slot and introduced mini-slots (or sub-slots or non-slot based schedules) to reduce transmission delay in the wireless section. Using a wide subcarrier spacing reduces transmission delay in the wireless section because the length of a single slot becomes inversely shorter. Mini-slots (or sub-slots) are designed for efficient support of URLLC scenarios and allow scheduling in units of 2, 4, or 7 symbols.

[0066] Furthermore, unlike LTE, NR defines uplink and downlink resource allocation at the symbol level within a single slot. To reduce HARQ latency, a slot structure was defined that allows HARQ ACK / NACK to be transmitted directly within the transmission slot; this slot structure is described as a self-contained structure.

[0067] NR is designed to support a total of 256 slot formats, of which 62 are used in 3GPP Rel-15. Additionally, it supports common frame structures that form FDD or TDD frames through various slot combinations. For example, it supports slot structures where all slot symbols are set to downlink, slot structures where all symbols are set to uplink, and slot structures where downlink and uplink symbols are combined. Furthermore, NR supports data transmission being distributed and scheduled across one or more slots. Therefore, base stations can use a Slot Format Indicator (SFI) to inform a terminal whether a slot is a downlink slot, an uplink slot, or a flexible slot. Base stations can indicate the slot format by using the SFI to indicate an index of a table configured via UE-specific RRC signaling, or they can indicate it dynamically via Downlink Control Information (DCI) or statically or semi-statically via RRC.

[0068] <NR 물리 자원 >

[0069] Regarding physical resources in NR, antenna ports, resource grids, resource elements, resource blocks, and bandwidth parts are considered.

[0070] An antenna port is defined such that the channel carrying a symbol on the antenna port can be inferred from the channel carrying another symbol on the same antenna port. If the large-scale property of the channel carrying a symbol on one antenna port can be inferred from the channel carrying a symbol on another antenna port, the two antenna ports can be said to be in a QC / QCL (quasi co-located or quasi co-location) relationship. Here, the large-scale property includes one or more of delay spread, Doppler spread, frequency shift, average received power, and received timing.

[0071] FIG. 3 is a diagram illustrating a resource grid supported by wireless access technology to which the present embodiment can be applied.

[0072] Referring to FIG. 3, a resource grid may exist for each numerator because NR supports multiple numerators on the same carrier. Additionally, a resource grid may exist depending on the antenna port, subcarrier spacing, and transmission direction.

[0073] A resource block consists of 12 subcarriers and is defined only in the frequency domain. Additionally, a resource element consists of one OFDM symbol and one subcarrier. Therefore, as shown in Fig. 3, the size of a single resource block can vary depending on the subcarrier spacing. Furthermore, NR defines "Point A," which serves as a common reference point for the resource block grid, as well as common resource blocks, virtual resource blocks, etc.

[0074] FIG. 4 is a diagram illustrating the bandwidth part supported by the wireless access technology to which the present embodiment can be applied.

[0075] In NR, unlike LTE where the carrier bandwidth is fixed at 20 MHz, the maximum carrier bandwidth is set from 50 MHz to 400 MHz depending on the subcarrier interval. Therefore, it is not assumed that all terminals use this entire carrier bandwidth. Accordingly, in NR, as shown in Fig. 4, a Bandwidth Part (BWP) can be designated within the carrier bandwidth for the terminal to use. Additionally, a Bandwidth Part is associated with a single numerator and consists of a subset of a continuous common resource block, and can be dynamically activated over time. Up to four Bandwidth Parts are configured for the uplink and downlink respectively, and data is transmitted and received using the Bandwidth Part activated at a given time.

[0076] In the case of paired spectrum, the uplink and downlink bandwidth parts are set independently, whereas in the case of unpaired spectrum, the downlink and uplink bandwidth parts are paired to share a center frequency in order to prevent unnecessary frequency re-tuning between downlink and uplink operations.

[0077] <NR 초기 접속>

[0078] In NR, the terminal performs cell search and random access procedures to connect to the base station and perform communication.

[0079] Cell search is a procedure in which a terminal uses a Synchronization Signal Block (SSB) transmitted by a base station to synchronize with the corresponding base station's cell, obtain a physical layer cell ID, and acquire system information.

[0080] FIG. 5 is a diagram illustrating an exemplary synchronization signal block in a wireless access technology to which the present embodiment can be applied.

[0081] Referring to FIG. 5, the SSB consists of a PSS (primary synchronization signal) and an SSS (secondary synchronization signal) each occupying 1 symbol and 127 subcarriers, and a PBCH spanning 3 OFDM symbols and 240 subcarriers.

[0082] The terminal monitors the SSB in the time and frequency domains and receives the SSB.

[0083] SSBs can be transmitted up to 64 times within 5ms. Multiple SSBs are transmitted via different transmission beams within the 5ms timeframe, and the terminal performs detection by assuming that an SSB is transmitted every 20ms when viewed from the perspective of a specific beam used for transmission. The number of beams available for SSB transmission within the 5ms timeframe can increase as the frequency band increases. For example, up to 4 SSB beams can be transmitted at 3GHz or lower, up to 8 beams in the frequency band from 3GHz to 6GHz, and up to 64 different beams can be used to transmit SSBs in the frequency band above 6GHz.

[0084] Two SSBs are included in a single slot, and the starting symbol and number of repetitions within the slot are determined according to the subcarrier interval as follows.

[0085] Meanwhile, unlike the SS of conventional LTE, the SSB is not transmitted at the center frequency of the carrier bandwidth. That is, the SSB can be transmitted even at locations other than the center of the system band, and multiple SSBs can be transmitted across the frequency domain when broadband operation is supported. Accordingly, the terminal monitors the SSB using a synchronization raster, which is a candidate frequency location for monitoring the SSB. The carrier raster, which is information on the center frequency location of the channel for initial connection, and the synchronization raster were newly defined in NR, and the synchronization raster is set with a wider frequency interval compared to the carrier raster, thereby supporting fast SSB search by the terminal.

[0086] The terminal can obtain the MIB through the PBCH of the SSB. The Master Information Block (MIB) contains minimum information for the terminal to receive the Remaining Minimum System Information (RMSI) broadcast by the network. Additionally, the PBCH may include information regarding the location of the first DM-RS symbol in the time domain, information for the terminal to monitor SIB1 (e.g., SIB1 numeral information, information related to SIB1 CORESET, search space information, PDCCH related parameter information, etc.), and offset information between the Common Resource Block and the SSB (the absolute location of the SSB within the carrier is transmitted via SIB1). Here, the SIB1 numeral information is applied identically to some messages used in the random access procedure for the terminal to connect to the base station after completing the cell search procedure. For example, the SIB1 numeral information may be applied to at least one of messages 1 to 4 for the random access procedure.

[0087] The aforementioned RMSI may refer to SIB1 (System Information Block 1), and SIB1 is broadcast periodically (e.g., 160ms) from the cell. SIB1 contains information necessary for the terminal to perform the initial random access procedure and is transmitted periodically via PDSCH. To receive SIB1, the terminal must receive the numerology information used for transmitting SIB1 and the CORESET (Control Resource Set) information used for scheduling SIB1 via PBCH. The terminal checks the scheduling information for SIB1 using SI-RNTI within the CORESET and obtains SIB1 on the PDSCH according to the scheduling information. The remaining SIBs, excluding SIB1, may be transmitted periodically or upon the terminal's request.

[0088] FIG. 6 is a diagram illustrating a random access procedure in a wireless access technology to which the present embodiment can be applied.

[0089] Referring to FIG. 6, when cell search is completed, the terminal transmits a random access preamble for random access to the base station. The random access preamble is transmitted via PRACH. Specifically, the random access preamble is transmitted to the base station via PRACH, which consists of a series of radio resources in specific slots that are repeated periodically. Generally, when the terminal initially connects to a cell, a contention-based random access procedure is performed, and when performing random access for Beam Failure Recovery (BFR), a non-contention-based random access procedure is performed.

[0090] The terminal receives a random access response for the transmitted random access preamble. The random access response may include a random access preamble identifier (ID), an UL Grant (uplink radio resource), a temporary C-RNTI (Temporary Cell - Radio Network Temporary Identifier), and a TAC (Time Alignment Command). Since a single random access response may contain random access response information for one or more terminals, the random access preamble identifier may be included to indicate which terminal the included UL Grant, temporary C-RNTI, and TAC are valid for. The random access preamble identifier may be an identifier for the random access preamble received by the base station. The TAC may be included as information for the terminal to coordinate uplink synchronization. The random access response may be indicated by the random access identifier on the PDCCH, namely the RA-RNTI (Random Access - Radio Network Temporary Identifier).

[0091] A terminal that receives a valid random access response processes the information contained in the random access response and performs a transmission scheduled to the base station. For example, the terminal applies a TAC and stores a temporary C-RNTI. Additionally, using a UL Grant, it transmits data stored in the terminal's buffer or newly generated data to the base station. In this case, information that can identify the terminal must be included.

[0092] Finally, the terminal receives a downlink message to resolve competition.

[0093] <NR CORESET>

[0094] The downlink control channel in NR is transmitted in a CORESET (Control Resource Set) with a length of 1 to 3 symbols, and transmits uplink / downlink scheduling information, SFI (Slot format Index), TPC (Transmit Power Control) information, etc.

[0095] In this way, NR introduced the concept of CORESET to ensure system flexibility. CORESET (Control Resource Set) refers to time-frequency resources for downlink control signals. A terminal can decode control channel candidates by using one or more search spaces from the CORESET time-frequency resources. Quasi CoLocation (QCL) assumptions were established for each CORESET, and these are used to indicate characteristics regarding the analog beam direction in addition to the characteristics assumed by conventional QCL, such as delay spread, Doppler spread, Doppler shift, and mean delay.

[0096] Figure 7 is a diagram for explaining CORESET.

[0097] Referring to FIG. 7, CORESET can exist in various forms within a single slot and within the carrier bandwidth, and in the time domain, CORESET can be composed of up to 3 OFDM symbols. Additionally, CORESET is defined as a multiple of 6 resource blocks up to the carrier bandwidth in the frequency domain.

[0098] The first CORESET is specified via the MIB as part of the initial bandwidth part configuration to enable the reception of additional configuration and system information from the network. After establishing a connection with the base station, the terminal can be configured by receiving one or more CORESET information via RRC signaling.

[0099] Wider bandwidth operations

[0100] In the case of existing LTE systems, scalable bandwidth operation was supported for any LTC Component Carrier (CC). That is, depending on the frequency deployment scenario, any LTE operator could configure a bandwidth ranging from a minimum of 1.4 MHz to a maximum of 20 MHz when configuring a single LTE CC, and normal LTE terminals supported a transmit / receive capability of 20 MHz bandwidth for a single LTE CC.

[0101] However, in the case of NR, the design is made to enable support for NR terminals with different transmit / receive bandwidth capabilities through a single wideband NR CC. Accordingly, it is required to configure one or more bandwidth parts (BWPs) consisting of subdivided bandwidths for any NR CC, and to support flexible wider bandwidth operation through different bandwidth part configurations and activations for each terminal.

[0102] Specifically, in NR, one or more bandwidth parts can be configured through a single serving cell configured from the perspective of a terminal, and the terminal is defined to activate one downlink bandwidth part (DL bandwidth part) and one uplink bandwidth part (UL bandwidth part) in the serving cell to use for uplink / downlink data transmission and reception. In addition, for terminals where multiple serving cells are configured, i.e., terminals to which CA is applied, it is defined to activate one downlink bandwidth part and / or uplink bandwidth part for each serving cell to use the wireless resources of the serving cell for uplink / downlink data transmission and reception.

[0103] Specifically, an initial bandwidth part for the initial access procedure of a terminal is defined in any serving cell, and one or more terminal-specific (UE-specific) bandwidth parts are configured for each terminal through dedicated RRC signaling, and a default bandwidth part for a fallback operation can also be defined for each terminal.

[0104] However, depending on the capability and bandwidth part(s) configuration of the terminal in any serving cell, it may be defined to simultaneously activate and use multiple downlink and / or uplink bandwidth parts, but in NR rel-15, it is defined to activate and use only one downlink bandwidth part (DL bandwidth part) and one uplink bandwidth part (UL bandwidth part) at any time in any terminal.

[0105] In this specification, frequencies, frames, subframes, resources, resource blocks, regions, bands, subbands, control channels, data channels, synchronization signals, various reference signals, various signals, or various messages related to NR (New Radio) may be interpreted in the sense used in the past or present, or in various senses used in the future.

[0106]

[0107] Below, we will specifically explain how to perform a random access procedure in an Ambient IoT environment with reference to the relevant drawings.

[0108] The present disclosure proposes a monitoring window setting method for efficiently receiving R2D messages retransmitted from a reader device when an Ambient IoT terminal (also referred to as an Ambient IoT device or Ambient IoT apparatus in the present disclosure) performing a random access procedure in an Ambient Internet of Things (Ambient IoT; referred to as Ambient IoT or A-IoT in the present disclosure) system of a 3GPP (3rd Generation Partnership Project) wireless access network (hereinafter referred to as "5G" or "NR [New Radio]" in the present disclosure) or a next-generation wireless access network (hereinafter referred to as "5G-Advanced or 6G" in the present disclosure) fails to receive an R2D (Reader-to-Device) message or fails to transmit a D2R (Device-to-Reader) message.

[0109] In recent years, IoT technology has garnered significant attention in wireless communication. IoT technology has evolved to enable a greater number of interconnected objects, thereby improving industrial productivity and quality of life. NB-IoT and eMTC technologies are examples of this. However, to build a more effective IoT ecosystem, improvements are needed in various aspects, such as the size, form factor, price, complexity, power consumption, and coverage of IoT devices.

[0110] RFID is a representative technology service of the IoT. The advantages of RFID include very low complexity, and RFID tags have a very small form factor. However, RFID supports a very narrow coverage area with a reading distance of only a few meters, is labor-intensive due to handheld scanning, and requires high deployment costs due to the installation costs of RFID portals / gates. Therefore, RFID has limitations in supporting seamless service and coverage in large-scale networks.

[0111] To meet these demands, research on Ambient IoT technology has been conducted. Ambient IoT terminals feature a lower form factor compared to conventional IoT terminals and support energy harvesting based on battery-less operation and minimal energy storage capability, enabling them to operate without charging or with minimal power consumption. Furthermore, research is underway to support wider coverage based on higher power efficiency and to enable the utilization of RF signals supported by existing networks.

[0112] 3GPP is conducting research on protocol stacks and signaling procedures that take into account the low form factor and battery capacity characteristics of Ambient IoT terminals, such as less than 1 μW or less than several hundred μW. In particular, definitions are being made for the paging message functionality, which is the first message transmitted by a reader or base station to an Ambient IoT terminal for wireless access of the Ambient IoT terminal, and the random access procedure of the Ambient IoT terminal.

[0113] FIG. 8 is a diagram illustrating the Reader / Tag operations and tag state of RFID.

[0114] RFID technology, the foundation of Ambient IoT technology, is "EPC TM It is defined in the document "Radio-Frequency Identity Protocols Generation-2 UHF RFID". The document defines the protocol between the Reader and the Tag and adopts a slotted-ALOHA-based random access procedure. As shown in Fig. 8, there are three main "Select, Inventory, Access" operations.

[0115] The Select operation is an action in which the Reader selects one or more tag populations, and consists of "Select" and "Challenge" commands. At this time, the Tag enters the Ready state. The Select command is a mandatory operation, while the Challenge command is optional. The Select command allows the Reader to select a set of Tags based on user-defined criteria. The Inventory operation prepares for Access by having the Reader identify and detect each Tag, and generating a unique random number based on commands and responses with each Tag. The Access operation involves the Reader communicating with each Tag to perform procedures such as Read, Write, and Authenticate.

[0116] In the following, the method by which an ambient IoT terminal performs a random access procedure will be explained in detail with reference to the relevant drawings.

[0117] In the present disclosure, the ambient IoT device may be referred to by various terms such as terminal, ambient IoT terminal, A-IoT terminal, ambient IoT device, IoT device, and IoT terminal. Additionally, the reader may be referred to by various terms such as reader device, reader device, base station, intermediate node, and general terminal, and may include a base station of the aforementioned topology 1 or an intermediate node of topology 2, for example, a UE. Furthermore, the carrier wave node (CW node) is a device that transmits carrier waves for energy harvesting and may include a base station, a reader, or a CW node. Additionally, in describing the link between the reader and the ambient IoT device, transmission from the reader to the ambient IoT device is referred to as R2D (Reader-to-Device) transmission, and conversely, transmission from the ambient IoT device to the reader is referred to as D2R (Device-to-Reader) transmission. Additionally, the physical channel for R2D transmission is referred to as PRDCH (Physical Reader-to-Device Channel), and the physical channel for D2R transmission is referred to as PDRCH (Physical Device-to-Reader Channel). However, these terms are provided as examples and are not limited thereto; other terms may be used if the technical concept of the present disclosure can be applied substantially identically.

[0118] For example, Ambient IoT terminals can be classified into three types as shown in Table 2 below.

[0119] DeviceTypeEnergyStoragePeak PowerConsumptionAmplificationUL Independentsignal generationUL Tx methodPassiveDevice 1Yes≤ 1 μWNoNoBackscatteringfrom external CWDevice 2aYes≤ a few hundred μWYes (DL and / or UL)NoBackscatteringfrom external CWActiveDevice 2bYes≤ a few hundred μWYes (DL and / or UL)YesGenerated internally

[0120] In Table 2, the difference between Passive and Active lies in the presence or absence of independent signal generation functions and hardware within the Ambient IoT terminal. It is defined as Passive if there is no independent signal generation function for uplink signal transmission, and Active if there is. Device 1 has a maximum power consumption of 1 μW or less and lacks independent signal generation and amplification functions. Additionally, the uplink of the Ambient IoT terminal is transmitted via backscattering of the external carrier wave signal. Device 2a has a maximum power consumption of several hundred μW or less, does not support independent signal generation, but supports UL / DL amplification functions. Furthermore, UL is transmitted via backscattering of the external carrier wave signal. Device 2b has a maximum power consumption of several hundred μW or less and supports independent signal generation and UL / DL amplification functions. Additionally, UL is transmitted through the device's internal signal generation.

[0121] Meanwhile, the common feature of Device 1, 2a, and 2b discussed by 3GPP to date is that they are equipped with energy storage inside the Ambient IoT terminal. However, Ambient IoT terminals may have energy storage of limited capacity depending on the topology and deployment scenario. In this case, limited energy storage refers to a storage device composed of small-sized capacitors. To support seamless communication between a Reader and an Ambient IoT device, protocols and signaling to support energy harvesting need to be defined.

[0122] FIGS. 9 and FIGS. 10 are drawings illustrating a connectivity topology for an A-IoT network and device to which the present embodiment can be applied.

[0123] Discussions regarding Ambient IoT topologies are ongoing in the standard. FIGS. 9 and FIGS. 10 are Ambient IoT topologies applicable in the present disclosure, and topologies 3 and 4 defined in TR 38.848 are also applicable.

[0124] It was decided to support paging messages at the Access Stratum (AS) layer between Ambient IoT terminals and readers / base stations, but since existing paging messages are difficult to support, A-IoT paging messages are newly defined. The purpose of A-IoT paging messages is to identify Ambient IoT terminal(s), select / determine a radio resource, and send a Device-to-Reader (D2R) response message to the reader.

[0125] To identify A-IoT device(s), the paging message may include identifier information types in the form of Table 3.

[0126] Cases Information Type Recipient Case 1 Single A-IoT device ID A single A-IoT Device Case 2 Group ID Multiple A-IoT device(s) mapped to a Group ID Case 3 No ID-related information All A-IoT device(s) receiving A-IoT paging messages Case 4 Multiple A-IoT device IDs Multiple A-IoT device IDs

[0127] In relation to the radio resource selection / determination method for D2R (Msg1) transmission of the aforementioned Ambient IoT terminal, it can also be defined how (implicit / explicit / configured / preconfigured) or through which resource (dedicated / shared) D2R transmission is performed.

[0128] FIG. 11 is a diagram illustrating the procedure of the Access Stratum (AS) layer between an A-IoT terminal and a reader according to one embodiment. Referring to FIG. 11, the procedure of the AS layer between an A-IoT device and a reader is defined.

[0129] Step A is the step where the reader sends an A-IoT paging message to wake up the A-IoT device. In this case, the A-IoT paging message is triggered by the reader receiving a service request.

[0130] Step B is a step for random access between the reader and the A-IoT device. In this case, the D2R data transmission message includes the Device ID.

[0131] Step C is the data transmission step between the reader and the A-IoT device following random access by the A-IoT device. In this case, it can be a message intended to instruct the A-IoT device to perform a command service. Step C1 (R2D data transmission) is the step where the reader transmits a message to the device to transmit a command. Step C2 (D2R data transmission) is the step of transmitting a response message from the device that received the Step C1 message. Steps A, B, C1, and C2 may be configured differently depending on the type of service: inventory-only, command-only, or inventory and command.

[0132] FIG. 12 is a diagram illustrating a wireless interface protocol stack between an A-IoT terminal and a reader according to one embodiment.

[0133] Figure 12 shows the protocol stack for the wireless interface between an A-IoT device and a reader. As shown in Figure 12, since the device and the reader only support the PHY and MAC layers, they may not support the RRC, SDAP, PDCP, and RLC layers, which are layers higher than the MAC layer.

[0134] Meanwhile, for the random access procedure of Ambient IoT terminal(s), the Slotted-ALOHA random access procedure was adopted as the default. Contention-based (CBRA) and contention-free (CFRA) access procedures can be defined for a single terminal, a group of terminals, and all terminals. Additionally, "4-step", "3-step", and "2-step" random access type procedures based on CBRA and CFRA can also be defined.

[0135] FIG. 13 is a diagram illustrating a 3-step CBRA procedure according to one embodiment. FIG. 14 is a diagram illustrating a CFRA procedure according to one embodiment.

[0136] Figures 13 and 14 are examples of 3-step CBRA and CFRA procedures based on the standards agreed upon to date. A-IoT devices can select or know the CBRA and CFRA procedures explicitly or implicitly through device ID information or access occasion information within paging messages or A-IoT trigger messages.

[0137] Figure 13 shows an example of a 3-step CBRA procedure for an A-IoT device. Paging messages include identifier information for the purpose of distinguishing them from paging messages transmitted by other readers and avoiding duplicate reception. Paging or A-IoT trigger messages include wireless resource information or access occasion information required by the device to transmit a D2R (Msg1) message.

[0138] A device receiving a D2R(Msg1) message may randomly select one or more resources or access occasions consisting of time, frequency, or code sequences. The device may transmit D2R(Msg1) including random ID or AS ID information. The reason for including random ID and AS ID is to identify the device through the exchange of random ID / AS ID within Msg1 and Msg2, and to perform contention resolution and avoid contention conflicts.

[0139] A reader that receives Msg1 may transmit R2D (Msg2) to the device, including the random ID or AS ID information received via Msg1 and dedicated resource information for Msg3. If the random ID (or AS ID) included in the received Msg2 is identical to the random ID (AS ID) it transmitted in Msg1, the device determines that contention resolution has been successfully performed and may transmit Msg3. Msg3 may include a device ID and upper layer data information.

[0140] Msg4 may contain success / failure indication information to handle the reader's failure to receive Msg3, and it may not necessarily be a message that needs to be transmitted or received. If Msg4 transmission or reception is required, the Reader / base station transmits Msg4 to the A-IoT device(s), and this can be assumed to be a 4-step RA procedure. In addition to Msg4, additional message transmission or reception between the A-IoT device and the reader / base station may occur as needed. However, discussions are still ongoing regarding which random access procedure type the A-IoT device(s) will determine during the random access process, and what information is required in the paging and R2D messages transmitted by the Reader / base station for the random access decision.

[0141] Figure 14 illustrates an example of a CFRA procedure for an A-IoT device. The paging message includes a device ID and dedicated resource information for transmitting D2R messages. Due to the nature of CFRA, the device skips the contention resolution procedure and then transmits a D2R (Msg1) message via a dedicated resource and access occasion. The D2R (Msg1) message may include a device ID, upper layer data, and a random ID or AS ID. The random ID or AS ID can be used for the purpose of scheduling dedicated resources for A-IoT data transmission after random access and for device identification. If AS ID information is pre-configured in the device, the device transmits the AS ID; if AS ID information is not pre-configured in the device, it may transmit including a random ID.

[0142] A reader that receives D2R(Msg1) can transmit an R2D(Msg2) message containing dedicated resource information required for the device's A-IoT data transmission and random ID or AS ID information. The reader can decide which information to use between the random ID and the AS ID, and depending on the decision, can transmit Msg2 containing the necessary information.

[0143] FIG. 15 is a diagram illustrating an FDMA-based D2R and an R2D transmission corresponding to the D2R of multiple A-IoT terminals according to one embodiment. FIG. 16 is a diagram illustrating an FDMA-based D2R and an R2D transmission corresponding to the D2R of a single A-IoT terminal according to one embodiment. FIG. 17 is a diagram illustrating an FDMA-based D2R and an R2D transmission corresponding to the D2R of a single A-IoT terminal according to another embodiment. FIG. 18 is a diagram illustrating a TDMA-based D2R and an R2D transmission corresponding to the D2R of multiple A-IoT terminals according to one embodiment. FIG. 19 is a diagram illustrating a TDMA-based D2R and an R2D transmission corresponding to the D2R of a single A-IoT terminal according to one embodiment.

[0144] In addition, the standard is also discussing communication methods based on FDM(A), TDM(A), and CDM(A) in A-IoT systems. Detailed specification definitions are underway regarding support methods for frequency, time, or code sequence-based communication in wireless resource allocation, and discussions are also underway regarding which method to adopt. Figures 15, 16, 17, 18, and 19 illustrate various embodiments of various D2R and R2D transmission methods based on FDM(A) and / or TDM(A).

[0145] FIGS. 15 through 19 assume a procedure in which A-IoT devices perform random access in different steps, such as 2-step or 3-step. Based on this, when an A-IoT device transmits a D2R message using FDMA or TDMA, an embodiment according to the corresponding R2D transmission method is shown. However, this is not limited thereto, and there may be other additional embodiments.

[0146] FIG. 15 shows an example of FDMA-based D2R (Msg1) transmission and R2D (Msg2) transmission corresponding to D2R messages transmitted by multiple A-IoT devices. FIG. 15 shows an example of FDMA-based D2R (Msg1) transmission and sequential transmission of R2D (Msg2) messages corresponding to D2R messages transmitted by a single A-IoT device. This is a case where a reader that receives a D2R message transmitted by an A-IoT device transmits a corresponding R2D message individually and sequentially for each D2R message.

[0147] FIG. 17 is similar to the method of FIG. 16, but differs in that, from the reader's perspective, the transmission of R2D(Msg2) is triggered for device 2, which first receives the D2R message, and the D2R(Msg3) message transmitted by device 2 is executed first. Subsequently, it is a case where an R2D message corresponding to the D2R message transmitted by device 1 is transmitted.

[0148] FIG. 18 shows an example of TDMA-based D2R (Msg1) transmission and R2D (Msg2) transmission corresponding to D2R messages transmitted by multiple A-IoT devices. FIG. 19 shows a case where an A-IoT device transmits D2R (Msg1) based on TDMA and a reader transmits R2D messages through a different frequency than the A-IoT device. In this case, the reader can transmit a corresponding R2D message for each D2R message transmitted by the A-IoT device.

[0149] As shown in Table 4, D2R and R2D message transmission and reception and timing relationships can be defined considering the processing time of the A-IoT device and the reader / base station. R2D_min From the Reader's perspective, it refers to the minimum time required from the transmission of an R2D message to the transmission of the corresponding D2R message. D2R_min From the perspective of the Device, it refers to the minimum time required from the transmission of a D2R message to the transmission of the corresponding R2D message. D2R_max represents the maximum time from the device's perspective during which the corresponding R2D message must be transmitted from the transmission of the D2R message. In other words, the transmission timing of the R2D (Msg2) message corresponding to the D2R (Msg1) message is [T D2R_min , T D2R_max It can be defined that it must occur within the ] time interval. Additionally, consider that the reader can continuously transmit two different R2D transmissions to a single device. In this case, the minimum time between R2D transmissions is T R2D_R2D_min It can be defined as. Additionally, the same device can transmit two different D2R transmissions consecutively, and the minimum time between each D2R transmission is T. D2R_D2R_min It can be defined as.

[0150] T R2D_min: Minimum time between a R2D transmission and the corresponding D2R transmission following it.T D2R_min : Minimum time between a D2R transmission and the corresponding R2D transmission following it.T D2R_max : Maximum time between the D2R transmission and the corresponding R2D transmission following it, so that the R2D transmission timing is expected to be within [T D2R_min ,T D2R_max ], when a R2D transmission in response to a D2R transmission is expected for A-IoT Msg2 response to A-IoT Msg1 for the A-IoT device. See clause 6.3 for message descriptions.T R2D_R2D_min : Minimum time between two different consecutive R2D transmissions to the same A-IoT device.T D2R_D2R_min : Minimum time between two different consecutive D2R transmissions from the same A-IoT device.For the time interval between a R2D transmission and the corresponding D2R transmission following it, there are two options studied:Option 1: Define a maximum timeT R2D_maxbetween a R2D transmission and the corresponding D2R transmission following it, so that the device transmits D2R transmission within [T R2D_min ,T R2D_max ].Option 2: The corresponding D2R transmission timingT R2D Following a R2D transmission is determined based on the control information in the R2D transmission, whereT R2D ≥T R2D_min .

[0151] Meanwhile, 3GPP is considering a method for readers to retransmit Msg2 to devices that failed to receive Msg3. If Msg2 contains information for multiple devices, the retransmitted Msg2 may include only the random ID information of the devices that failed to receive it. From a device's perspective, in order to receive the retransmitted Msg2, it is highly likely that separate monitoring start / end times, monitoring windows, and related configuration information for Msg2 reception will be reflected in the specifications.

[0152] In addition, the start time and interval for the device's Msg2 monitoring can be defined. The device's monitoring-related setting values ​​can be determined based on parameters considering the processing time in Table 4. To date, only parameters for the device's Msg2 monitoring to receive the Msg2 initially transmitted by the reader have been considered. It is necessary to define setting information regarding the monitoring start, interval, and period for the scenario where the reader retransmits the Msg2 and for the device to receive the retransmitted Msg2. In other words, detailed device behavior considering Msg2 reception failure needs to be defined.

[0153] If the Reader fails to receive an uplink third message (Msg3) corresponding to a specific terminal identifier (e.g., Random ID), it may retransmit a downlink second message (Msg2) to that specific terminal. In particular, even if the initial second message includes scheduling information for multiple terminals, the retransmitted second message may be configured to include only the identifiers (Random IDs) of terminals that failed to transmit the third message.

[0154] To determine whether the terminal re-accesses, a NACK (Negative Acknowledgement)-based feedback mechanism for Device-to-Reader (D2R) messages, such as the third message (Msg3), is supported. However, when implementing the NACK-based mechanism, specific details must be defined regarding whether to operate based on a timer or use an explicit message, and when the reader transmits feedback.

[0155]

[0156] Below, we will specifically explain how to perform a random access procedure in an Ambient IoT environment with reference to the relevant drawings.

[0157] The purpose of the present disclosure is to provide a method for configuring a monitoring window to efficiently receive one or more R2D messages (e.g., (Re-)Msg2 or Msg3 Feedback (ACK / NACK)) retransmitted by a reader when an A-IoT device performing random access in an Ambient IoT system that supports only the PHY and MAC layers fails to receive Msg2 or fails to transmit Msg3. Through the present disclosure, the device can efficiently complete the random access procedure by periodically performing monitoring operations in an ON / OFF manner to receive retransmitted R2D messages.

[0158] To this end, the device needs to define the start / stop / expiration times and the size of the monitoring window for receiving Msg2 or Msg3 feedback retransmitted by the reader. Based on the ON / OFF type monitoring window setting information, the device can efficiently receive (re-)Msg2 and Msg3 feedback with minimized energy consumption and transmit Msg3 accordingly.

[0159] Absence of device operation after R2D(Msg2) reception failure

[0160] FIG. 20 is a diagram illustrating the absence of a subsequent operation following the failure to receive Msg2 of an A-IoT terminal according to one embodiment.

[0161] Referring to FIG. 20, a problem is illustrated regarding the lack of subsequent action when the device fails to receive R2D (Msg2) or fails to transmit Msg3. Case ① in FIG. 20 is the case where the device fails to receive Msg2, and case ② is the case where the device fails to transmit Msg3. From the device's perspective, both case ① and case ② result in a failure to transmit Msg3. From the reader's perspective, in both case ① and case ②, Msg2 can be retransmitted or feedback information regarding Msg3 can be transmitted.

[0162] The Device receives a paging or PRDCH message (PHY control information or MAC layer) containing Msg1 access occasion resource information from the reader and backscattering Msg1 in response. The Device backscattering after the transmission of Msg1 is complete or based on the last point in time of the time-domain resource where Msg1 was transmitted T D2R_min Msg2 monitoring can start from this time. Also, the Device is [T D2R_min , T D2R_max ] During the monitoring period, Msg2 reception can be expected. Here, if the device fails to receive Msg2 during the monitoring period, it cannot transmit Msg3. Therefore, from the reader's perspective, even though it has transmitted Msg2, it fails to receive Msg3 during the monitoring period where it expects Msg3 reception.

[0163] As described above, the reader can retransmit Msg2 to devices that failed to receive Msg3. The reader transmits Msg2 containing the random IDs or device identification information of the device(s) received from i (i≥1) device(s). Subsequently, the reader can expect to receive i Msg3s from the i device(s) included in Msg2. If the reader fails to receive Msg3 from j (j≤i) device(s) among the i device(s), it can identify which device failed to transmit Msg3. Then, the reader can retransmit Msg2 or send Msg3 feedback (NACK) to the devices that failed to transmit Msg3.

[0164] In addition, methods to minimize power consumption during the device's monitoring of Msg2 are being discussed. However, the operation from the device's perspective regarding the case where the device fails to receive Msg2 and the reception of Msg2 retransmitted by the reader has not been defined. Therefore, it is necessary to consider the device-reader interaction to resolve the aforementioned issues.

[0165]

[0166] FIG. 21 is a diagram illustrating a procedure (2100) in which an Ambient IoT terminal performs random access according to one embodiment.

[0167] Referring to FIG. 21, the Ambient IoT terminal can receive resource information for transmitting a first message (Msg1), terminal-specific monitoring window configuration information, and maximum monitoring count information from a reader device (S2110).

[0168] According to one example, an Ambient IoT terminal may receive resource information and monitoring window configuration information for the transmission of a first message through an A-IoT paging message, PRDCH, PHY control information (R2D Control Information), or MAC PDU (e.g., CE).

[0169] Resource information for the first message transmission may include D2R (Device-to-Reader) dedicated resource information separated into time and frequency domains and access occasion information.

[0170] The monitoring window configuration information per terminal is setting information for performing periodic ON / OFF monitoring operations based on monitoring window start times and size / interval information that differ for each terminal. This configuration information includes various parameters related to the processing time between the Ambient IoT terminal and the reader device, for example, T Reference_time 1 , T D2R_min #n , T D2R #n , T D2R_max #n , T R2D_min #n , T R2D #n , T R2D_max #n This may include the back.

[0171] Additionally, the monitoring window configuration information may include an offset time between the initial second message (initial MSG2) monitoring window and the retransmitted second message ((re-)MSG2) monitoring window, or a value α which is time offset information between consecutive retransmitted message monitoring windows.

[0172] The maximum monitoring count information (k) is configuration information that indicates how many times a periodic monitoring window will be operated until the Ambient IoT terminal successfully receives the retransmitted second message or third message feedback information. That is, the maximum monitoring count information (k) includes information indicating the number of monitoring times and can be indicated in bit units. For example, k can be composed of 2 bits to indicate 1 to 4 times respectively. Alternatively, according to another example, k can be composed of 1 bit and pre-set to indicate 1 time if the bit value is 0 and n times if the bit value is 1. Here, n can be an integer greater than 1. For example, n can be set to any one of 2, 3, or 4.

[0173] Referring again to FIG. 21, the Ambient IoT terminal can transmit a first message through a selected time domain resource among the time domain resources included in the resource information (S2120).

[0174] Specifically, the Ambient IoT terminal can select or know whether to perform a contention-based random access (CBRA) procedure or a contention-free random access (CFRA) procedure explicitly or implicitly through device ID information or access occasion information included in an A-IoT paging message or an A-IoT trigger message.

[0175] If the Ambient IoT terminal performs contention-based random access (CFRA), the Ambient IoT terminal can transmit the first message (Msg1) through a dedicated scheduling resource allocated to it from the reader device. On the other hand, if the Ambient IoT terminal performs contention-based random access (CBRA), the Ambient IoT terminal can transmit the first message by arbitrarily selecting and occupying one of the resources and multiple access occupancy(s) classified by the time and frequency domains included in PRDCH.

[0176] In this case, the Ambient IoT terminal can include random ID or AS ID (Access Stratum ID) information in the first message, the D2R (Device-to-Reader) message, and transmit it to the reader device.

[0177] Referring again to FIG. 21, the Ambient IoT terminal can monitor a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the selected time domain resource and offset information included in the monitoring window configuration information (S2130).

[0178] Specifically, a periodic on / off type monitoring window may be initiated at the expected reception timing of a second message derived from a selected time domain resource or at specific times when a certain time has elapsed according to offset information from the point in time when the previous monitoring window ended.

[0179] For example, the point at which the monitoring window timer starts is the exact reception timing information (T) of the downlink message to be transmitted by the reader device for each terminal. D2R D#n Starts based on ), or, the minimum processing time (T) expecting message receptionD2R_min D#n It can be started based on ). In addition, the monitoring window timer for receiving the next retransmission second message ((re-)Msg2) after the terminal fails to receive the initial second message ((re-)Msg2) can perform periodic ON / OFF operations by restarting from the point in time after an offset time value (α) has elapsed since the previous monitoring window ended.

[0180] In the process of an Ambient IoT terminal performing monitoring during the operation period of the monitoring window initiated in this manner, if at least one of a second message, a retransmitted second message, or a third message feedback is received from a reader device within the monitoring window, the timer of the monitoring window may be stopped.

[0181] Additionally, the Ambient IoT terminal may stop the monitoring window not only when it successfully receives the aforementioned second message, retransmitted second message, or third message feedback, but also when it successfully receives one or more messages among the preamble, R-TAS (R2D Timing Acquisition Signal), SIP (Start Indicator Part) or CAP (Clock Acquisition Part) of R-TAS through PRDCH. After the monitoring window timer is stopped upon receiving the information, the Ambient IoT terminal may proceed to a preparation stage for transmitting the third message.

[0182] Referring again to FIG. 21, the Ambient IoT terminal can transmit a subsequent message to a reader device based on the received result from monitoring (S2140).

[0183] For example, after the monitoring window timer is stopped, the Ambient IoT terminal can perform specific subsequent transmission actions differently depending on the type of received message.

[0184] Specifically, the Ambient IoT terminal transmits a third message (Msg3) when a retransmission second message is received within the monitoring window, and can transmit a request for retransmission of the second message when feedback on the third message is received within the monitoring window. That is, upon receiving the retransmission second message, the Ambient IoT terminal prepares to transmit the third message and transmits it. Conversely, upon receiving feedback on the third message (NACK), since the Ambient IoT terminal has not received the initial second message, it transmits a message requesting the retransmission of the second message to the reader device.

[0185] On the other hand, an exception handling operation may be performed in the case where no message is received in the corresponding intervals despite the periodic monitoring results of the Ambient IoT terminal. The Ambient IoT terminal may repeat the monitoring window operation until the second message or third message feedback information is successfully received, and to this end, the number of operations can be controlled based on the maximum monitoring count counter information (k) that is pre-set. For example, if k=3, which is the maximum monitoring count information, is received as configuration information, the Ambient IoT terminal may operate the periodic monitoring window over 3 intervals.

[0186] Consequently, if none of the second message, the retransmitted second message, or the third message feedback is received until the number of times periodic on / off monitoring is performed reaches the maximum value according to the maximum monitoring count information, the Ambient IoT terminal may determine that the random access procedure has failed and wait for the next paging message. Alternatively, according to one example, if the second message (Msg2) is not received until the number of times monitoring is performed on an R2D message including the second message (Msg2), the retransmitted second message, or the third message feedback (Msg3 Feedback) message reaches the maximum value according to the maximum monitoring count information, the Ambient IoT terminal may determine that the random access procedure has failed and be configured to wait for the next paging message. That is, even if other messages are received, if the second message is not received, the corresponding random access procedure may be determined to have failed.

[0187] In this case, the Ambient IoT terminal may wait until the next paging round or a subsequent A-IoT paging message arrives to prevent unnecessary power consumption.

[0188] According to this, a method and device for performing a random access procedure in an ambient IoT environment can be provided. In addition, an energy-efficient random access procedure can be performed with minimal power consumption through ON / OFF-based periodic monitoring operations.

[0189] FIG. 22 is a diagram illustrating a procedure (2200) in which a reader device according to one embodiment performs random access. The description in FIG. 21 described above may be omitted to avoid redundant descriptions, and in this case, the omitted content may be applied substantially the same to the reader device as long as it does not contradict the technical concept of the invention.

[0190] Referring to FIG. 22, the reader device can transmit resource information for transmitting a first message (Msg1), monitoring window configuration information per terminal, and maximum monitoring count information to an Ambient IoT terminal (S2210).

[0191] According to one example, the reader device may transmit resource information and monitoring window configuration information for the transmission of the first message to an Ambient IoT terminal via an A-IoT paging message, PRDCH, PHY control information (R2D Control Information), or MAC PDU (e.g., CE).

[0192] Resource information for the first message transmission may include D2R (Device-to-Reader) dedicated resource information separated into time and frequency domains and access occasion information.

[0193] The monitoring window configuration information per terminal is setting information intended to instruct Ambient IoT terminals to perform periodic ON / OFF monitoring operations based on monitoring window start times and size / interval information that differ for each Ambient IoT terminal. This configuration information includes various parameters related to the processing time between the Ambient IoT terminal and the reader device, for example, T Reference_time 1 , T D2R_min #n , T D2R #n , T D2R_max#n , T R2D_min #n , T R2D #n , T R2D_max #n This may include the back.

[0194] Additionally, the monitoring window configuration information may include an offset time between the initial second message (initial MSG2) monitoring window and the retransmitted second message ((re-)MSG2) monitoring window, or a value α which is time offset information between consecutive retransmitted message monitoring windows.

[0195] The maximum monitoring count information (k) is configuration information that indicates how many times a periodic monitoring window will be operated until the Ambient IoT terminal successfully receives the retransmitted second message or third message feedback information. That is, the maximum monitoring count information (k) includes information indicating the number of monitoring times and can be indicated in bit units. For example, k can be composed of 2 bits to indicate 1 to 4 times respectively. Alternatively, according to another example, k can be composed of 1 bit and pre-set to indicate 1 time if the bit value is 0 and n times if the bit value is 1. Here, n can be an integer greater than 1. For example, n can be set to any one of 2, 3, or 4.

[0196] Referring again to FIG. 22, the reader device can receive a first message through a selected time domain resource among the time domain resources included in the resource information (S2220).

[0197] Specifically, the reader device can receive a first message according to a contention-based random access (CBRA) procedure or a contention-free random access (CFRA) procedure performed explicitly or implicitly by an Ambient IoT terminal through device ID information or access occasion information that it includes and transmits within an A-IoT paging message or an A-IoT trigger message.

[0198] If the Ambient IoT terminal performs contention-based random access (CFRA), the reader device can receive the first message (Msg1) through a dedicated scheduling resource allocated to the Ambient IoT terminal. On the other hand, if the Ambient IoT terminal performs contention-based random access (CBRA), the reader device can receive the first message through a single access occupant arbitrarily selected and occupied by the Ambient IoT terminal from among the resources separated by time and frequency domains provided in the PRDCH and a plurality of access occupant(s).

[0199] In this case, the reader device can receive and obtain random ID or AS ID (Access Stratum ID) information included in the D2R (Device-to-Reader) message, which is the first message transmitted by the Ambient IoT terminal.

[0200] Referring again to FIG. 22, the reader device can transmit a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on selected specific time domain resources and offset information included in the monitoring window configuration information (S2230).

[0201] Specifically, a periodic on / off type monitoring window can be initiated at intervals corresponding to the expected transmission timing of the second message derived from the selected time domain resource or at specific times according to offset information from the point in time when the previous monitoring window ended.

[0202] For example, the start time of the monitoring window in which the reader device transmits downlink messages is the exact transmission timing information (T) of the downlink messages to be transmitted by the reader device for each Ambient IoT terminal. D2R D#n It starts based on ), or, the minimum processing time (T) at which the Ambient IoT terminal expects to receive a message. D2R_min D#n It can be started based on ). In addition, when the Ambient IoT terminal recognizes that it has failed to receive the initial second message (initial Msg2) or has failed to receive the third message, the monitoring window for the reader device to transmit the next retransmission second message ((re-)Msg2) can be restarted from the point in time after an offset time value (α) has elapsed since the previous monitoring window ended, thereby performing periodic ON / OFF transmission operations.

[0203] Here, the retransmission of the second message or the third message feedback may be transmitted when it is determined that the reception of the third message has failed within the interval where the reception of the third message is expected after the second message has been transmitted.

[0204] In the process of the reader device performing a transmission operation during the period in which the monitoring window initiated in this manner operates, by successfully transmitting at least one of a second message, a retransmission second message, or a third message feedback from the reader device within the monitoring window, the Ambient IoT terminal can be induced to stop the timer of the monitoring window.

[0205] Additionally, the reader device may cause the Ambient IoT terminal to stop the monitoring window when transmitting one or more messages among the Preamble, R-TAS (R2D Timing Acquisition Signal), SIP (Start Indicator Part) or CAP (Clock Acquisition Part) of R-TAS, as well as the aforementioned second message, retransmission second message, or third message feedback, via PRDCH. After the monitoring window timer of the Ambient IoT terminal is stopped by transmitting the above information, the reader device causes the Ambient IoT terminal to proceed to the preparation stage for transmitting the third message, and can expect an uplink response accordingly.

[0206] Referring again to FIG. 22, the reader device can receive a subsequent message from the Ambient IoT terminal (S2240).

[0207] For example, when considering terminal operation after the monitoring window timer has stopped, the reader device may receive specific follow-up messages differently from the Ambient IoT terminal depending on the type of message it transmitted.

[0208] Specifically, the reader device receives a third message (Msg3) when it transmits a second retransmission message, and receives a second message retransmission request message when it transmits third message feedback. That is, when the reader device transmits the second retransmission message, the Ambient IoT terminal that receives it prepares to transmit the third message and transmits it, so the reader device receives the third message. Conversely, when the reader device transmits third message feedback (NACK), the Ambient IoT terminal, having not received the initial second message, receives a message from the terminal requesting the retransmission of the initial second message.

[0209] On the other hand, an exception handling operation may be performed for cases where no subsequent message is received from the Ambient IoT terminal in those intervals, despite the periodic message transmission of the reader device and the corresponding monitoring results of the Ambient IoT terminal. The reader device may repeat transmission in accordance with the monitoring window operation until the Ambient IoT terminal successfully receives and responds to the retransmission second message or third message feedback information, and to this end, the number of transmission and reception waiting times may be controlled based on the maximum monitoring count counter information (k) set in advance in the terminal. For example, if k=3, which is the maximum monitoring count information, is transmitted to the Ambient IoT terminal as configuration information, the reader device may operate in accordance with the Ambient IoT terminal operating the periodic monitoring window over three intervals.

[0210] Consequently, if a subsequent message is not received until the number of times a retransmitted second message or third message feedback is transmitted according to a periodic on / off monitoring window reaches a maximum value according to the maximum monitoring count information, the random access procedure of the Ambient IoT terminal can be determined to have failed. Alternatively, according to one example, if a third message (Msg3) corresponding to the successful reception of the second message is not received from the terminal until the number of times an R2D message, including a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) message, is transmitted reaches a maximum value according to the maximum monitoring count information, the reader device can determine that the random access procedure has failed. That is, even if the reader device receives other uplink messages, such as a request for retransmission of the second message, from the terminal, if the third message is ultimately not received until the maximum count is reached, the corresponding random access procedure can be determined to have failed.

[0211] In this case, the reader device may initiate a paging procedure in the next paging round or transmit a subsequent A-IoT paging message so that the Ambient IoT terminal can prevent unnecessary power consumption and attempt a new connection.

[0212] According to this, a method and device for performing a random access procedure in an ambient IoT environment can be provided. In addition, an energy-efficient random access procedure can be performed with minimal power consumption through ON / OFF-based periodic monitoring operations.

[0213]

[0214] Hereinafter, each embodiment related to a method for performing a random access procedure in an Ambient IoT environment will be described in detail with reference to the relevant drawings.

[0215] The present disclosure proposes a procedure and method between a device and a reader for monitoring Msg2 / Msg3 feedback (ACK / NACK) retransmitted by a reader in an ON / OFF manner following a failure to receive an R2D (e.g., Msg2) message or a failure to transmit a D2R (e.g., Msg3) message from the device.

[0216] If the Reader fails to receive Msg3 after transmitting (initial)Msg2, it may retransmit Msg2 or send a NACK message for Msg3. Therefore, when the device fails to receive Msg2 or fails to transmit Msg3, it must perform a monitoring operation to receive the R2D message that the reader will retransmit.

[0217] Accordingly, the present disclosure proposes a method for setting a periodic monitoring window in an ON / OFF form to receive an R2D (i.e., re-Msg2 or Msg3_Feedback) to be retransmitted by a reader after the device fails to receive Msg2, and the operation of the device based on said setting information. Furthermore, since the monitoring window proposed in the present disclosure operates based on different monitoring window setting information for each device, energy consumption can be reduced.

[0218] Reference time (T) to consider when determining the starting time of the Device's Msg2 monitoring Reference timeAs such, the end time of the last resource among the X time-domain resource(s) allocated for the transmission of Msg1 is being considered. That is, the time when the time-domain resource where the device completed the transmission of Msg1 ends, or the time when the last access occasion ends, can be considered as the reference time. Therefore, the device is at least T from the reference time. D2R_min Msg2 monitoring can start after the (processing time for preparing transmission and reception between device and reader) time.

[0219] To describe the scenario of the present disclosure in light of the foregoing, first, the device receives resource information via a PRDCH containing D2R resource information and access occasion(s) separated into time / frequency domains for A-IoT paging messages or Msg1 transmission.

[0220] In the case of CBRA, the device randomly selects one access occasion from n access occasions, and in the case of CFRA, it transmits Msg1 through the access occasion assigned to it. The device uses a reference time (T Reference time From ) T D2R_min Reception of (initial)Msg2 can be expected after the value has elapsed, and monitoring is performed simultaneously. At this time, the device [T D2R_min , T D2R_max If reception of (initial)Msg2 fails in the ] section, monitoring configuration information is required to receive R2D messages that the reader will transmit later.

[0221] After receiving Msg1 transmitted by the device, the Reader, T D2R_min After the value has passed, (initial)Msg2 is transmitted. At this time, the device is [T D2R_min , T D2R_maxIf (initial)Msg2 is not received in the ] interval, Msg3 cannot be transmitted. Nevertheless, after transmitting (Initial)Msg2, the reader T R2D_min From this point onward, the reader can expect to receive Msg3 through the dedicated Msg3 resource allocated to the device via (initial)Msg2. However, if the reader fails to receive Msg3, it can retransmit Msg2 or send a Msg3 feedback (NACK) to request retransmission of Msg3, as the reader successfully received Msg1 from the device.

[0222] After failing to receive (initial)Msg2, the device may receive (re-)Msg2 or Msg3 feedback within the monitoring window period proposed in this disclosure. If the device succeeds in receiving (re-)Msg2, it may transmit Msg3. However, if the device receives Msg3 feedback (NACK), it may transmit a (re-)Msg2 request message because it failed to receive (initial)Msg2. The foregoing details are summarized as follows.

[0223] 1. Device: Receive Msg0 or A-IoT paging or R2D control information

[0224] 2. Device: Send Msg1

[0225] 3. Reader: (initial) Send Msg2

[0226] 4. Device: (initial) Failure to receive Msg2 and subsequent failure to transmit Msg3

[0227] 5. Reader: Failed to receive Msg3

[0228] 6. Reader: Send R2D message ((re-)Msg2 or Msg3 Feedback(NACK))

[0229] 7. Device: Success in receiving the R2D in the monitoring window interval proposed in the present invention

[0230] A. Send Msg3 upon receiving Re-Msg2

[0231] B. Request Msg2 retransmission upon receipt of Msg3 Feedback (NACK)

[0232] In conclusion, the device needs to perform a separate monitoring operation to receive success / failure feedback (ACK / NACK) for receiving Re-Msg2 or Msg3 retransmitted by the reader.

[0233] FIG. 23 is a diagram illustrating the configuration of multiple monitoring windows according to one embodiment.

[0234] Referring to FIG. 23, a method for setting a monitoring window for different devices that failed to receive Initial Msg2 to receive one or more (Re-)Msg2 or Msg3 feedback (ACK / NACK) transmitted from the reader is illustrated.

[0235] As shown in FIG. 23, different devices have a reference time (T Reference_time ) and T D2R_min D#1 , T D2R D#1 , T D2R_max D#1 , T R2D_min D#1 , T R2D D#1 , T R2D_max D#1 , T D2R_min D#2 , T D2R D#2 , T D2R_max D#2 , T R2D_min D#2 , T R2D D#2 , T R2D_max D#2You can set the start and stop times of the monitoring window by considering time values ​​other than α.

[0236] The device can receive monitoring window settings and related information via PRDCH or PHY control information (R2D control Information) or MAC PDU (e.g., CE) containing resource information classified into time / frequency domains for A-IoT paging messages or Msg1 transmission.

[0237] Here, reference time 1 is (T Reference_time 1 ) This is the point in time when the last resource among the X time-domain resource(s) or access occasion(s) allocated for Msg1 transmission ends. Reference time 2 is (T Reference_time 2 This may be the point when the reader has completed sending (initial) Msg2.

[0238] T D2R_min D#n may be the monitoring start point for receiving an R2D(Msg2) message by the device that selected the nth access occasion, and reference time 1 and T D2R_min D#1 It can be calculated based on T D2R D#n is the reception timing of the R2D message of the device selecting the n-th access occasion or the transmission timing information of the reader's R2D message, which may be the start time of the monitoring window, and reference time 1 and T D2R_min D#1 It can be calculated based on T D2R_max D#n may be the point at which the device that selected the nth access occasion stops monitoring for receiving R2D messages, and reference time 1 and T D2R_min D#1 It can be calculated based on.

[0239] T R2D_min D#n may be the point in time when the reader begins to expect reception of Msg3 for the device that selected the nth access occasion when Msg1 was transmitted, and reference time 2 and T R2D_min D#1 It can be calculated based on. The above T R2D D#n may be the reception timing of Msg3 of the device that selected the nth access occasion when the reader transmits Msg1, or transmission timing information to be transmitted by the device, and reference time 2 and T R2D_min D#1 It can be calculated based on T R2D_max D#n may be the last point in time when the reader expects to receive Msg3 for the device that selected the nth access occasion when Msg1 was transmitted, and reference time 2 and T R2D_min D#1 It can be calculated based on.

[0240] α may be an offset time value between the initial Msg2 monitoring window and the (re-)Msg2 monitoring window. Alternatively, it may be an offset time value between the (re)Msg2-(re)Msg monitoring window. The offset may be defined as the size of a single access occasion in the time domain and the number of access occasions based thereon, or a chip- / block- / bit-level duration. Alternatively, the aforementioned T D2R_min D#n , T D2R D#n , T D2R_max D#n , T D2R_min D#n , T D2R D#n , T D2R_max D#nIt can be calculated as a combination of values. In addition, each device may have a different α value, and the devices may turn the monitoring window operation ON / OFF based on the α value.

[0241] Monitoring Window Timer Start Condition

[0242] Each option in FIG. 23 represents an example of an operation to turn monitoring ON / OFF based on different monitoring window start times and size / interval information for different devices. In the case of Option 1.1 and Option 1.2, the monitoring window timer proposed in this disclosure starts including initial Msg2. In Option 2.1 and Option 2.2, the monitoring window timer proposed in this disclosure starts after the failure to receive initial Msg2.

[0243] Option 1.1 is the exact reception timing information for the R2D message to be transmitted by the reader per device, T D2R D#n The monitoring window timer starts based on this. Option 1.2 is T, the point in time when the reader expects to receive the R2D message to be transmitted for each device. D2R_min D#n The monitoring window timer starts based on this.

[0244] Option 2.1 is T per device D2R D#n The monitoring window timer starts at a point that has elapsed by the α offset time value between the current time and the next (re-)Msg2. Option 2.2 is T per device D2R_min D#n The monitoring window timer starts from the point in time when the α offset time value between the next (re-)Msg2 has elapsed.

[0245] Option 1.1. T Reference_time 1 + TD2R D#n

[0246] Option 1.2. T Reference_time 1 + T D2R_min D#n

[0247] Option 2.1. T Reference_time 1 + T D2R D#n + α

[0248] Option 2.2. T Reference_time 1 + T D2R_min D#n + α

[0249] Monitoring Window Timer Stop Condition

[0250] Option 1.1 and Option 1.2 are based on reference time 1, T D2R_max D#n The monitoring window timer stops when the value is reached or when (re-)Msg2 or Msg3 feedback is successfully received. Options 2.1 and 2.2 cause the monitoring window timer to stop when α has elapsed since options 1.1 and 1.2, or when (re-)Msg2 or Msg3 feedback is successfully received. The monitoring window size is [T D2R D#n , T D2R_max D#n ] or [T D2R_min D#n , T D2R_max D#n It can also be calculated as a ] value.

[0251] Option 2.1 is T per device D2R D#n The monitoring window timer starts at a point that has elapsed by the α offset time value between the current time and the next (re-)Msg2. Option 2.2 is T per device D2R_min D#nThe monitoring window timer starts from the point in time when the α offset time value between the next (re-)Msg2 has elapsed.

[0252] Option 1.1. T Reference_time 1 + T D2R_max D#n or when (re-)Msg2 is received or when Msg3_Feedback is received

[0253] Option 1.2. T Reference_time 1 + T D2R_max D#n or when (re-)Msg2 is received or when Msg3_Feedback is received

[0254] Option 2.1. T Reference_time 1 + T D2R_max D#n + α or when (re-)Msg2 is received or when Msg3_Feedback is received

[0255] Option 2.2. T Reference_time 1 + T D2R_max D#n + α or when (re-)Msg2 is received or when Msg3_Feedback is received

[0256] If the Device successfully receives one or more of the following message(s) from the reader via PRDCH while the monitoring window timer is running, the window may be stopped and the device may proceed to the preparation phase for sending Msg3.

[0257] Option 1. (re-)Msg2

[0258] Option 2. Preamble

[0259] Option 3. R-TAS (R2D Timing Acquisition Signal)

[0260] Option 4. SIP (Start Indicator Part) of R-TAS

[0261] Option 5. CAP (Clock Acquisition Part) of R-TAS

[0262] Option 6. Msg3 Feedback

[0263] Monitoring Windows Timer Expiry Condition

[0264] If any of the following messages are not received from the reader via PRDCH before the monitoring window timer terminates, the window may explode. In this case, the device may determine that it failed to receive Msg2 or A-IoT random access. The device may then wait for a subsequent A-IoT paging message transmitted by the reader or the next paging round.

[0265] Option 1. Msg2

[0266] Option 2. Preamble

[0267] Option 3. R-TAS (R2D Timing Acquisition Signal)

[0268] Option 4. SIP (Start Indicator Part) of R-TAS

[0269] Option 5. CAP (Clock Acquisition Part) of R-TAS

[0270] Option 6. Msg3 Feedback

[0271] Conditions for terminating the device's monitoring window and determining random access failure can also be set. The device can be configured to monitor for a maximum number of (Re-)Msg2 / Msg3 feedback messages until Msg2 or Msg3 feedback information is successfully received. For example, if k=3 when receiving count counter information (k), the device can activate the monitoring window in 3 intervals. If the device does not receive Msg2 or Msg3 feedback information within 3 monitoring window intervals, the device determines that random access has failed and may wait for the next paging message.

[0272] Additionally, the unit constituting the monitoring window size may be defined as a slot or monitoring occasion and duration, the number of access occasions in the time domain, or one or more bit-level length / durations, one or more chip-level length / durations, or one or more block-level length / durations. Alternatively, it may be defined as an offset value between initial Msg2-(re)Msg2 and (re)Msg2-(re)Msg2. Or, T D2R (R2D message timing information corresponding to the D2R message), T D2R_min , T D2R_max , T R2D_min , T R2D_max , T R2D_R2D (Time between two consecutive R2D messages transmitted by the reader), T R2D_R2D_min (T R2D_R2D minimum time of), T R2D_R2D_max (T R2D_R2D It can be defined in units of time (e.g., ms, μs, OFDM symbol), such as the maximum time of

[0273] The operation flow of the device proposed in this disclosure is as follows. The device receives monitoring window configuration information, which differs for each device, from a reader to monitor one or more Msg2 / Msg3 feedbacks. Each device(s) performs monitoring based on the monitoring window configuration information after transmitting Msg1. If the device succeeds in receiving (re-)Msg2 / Msg3 feedback within the window period, it stops the window timer and prepares to transmit Msg3. However, if the device fails to receive Msg2 or Msg3 feedback until the monitoring window timer expires or when the counter (K) information reaches a maximum value, it determines that Msg2 reception and random access have failed. Subsequently, the device may wait until the next paging round or a subsequent paging message.

[0274] FIG. 24 is a diagram illustrating a monitoring window-based (re-)Msg2 / Msg3 feedback operation according to one embodiment.

[0275] Based on FIG. 24, an example and procedure of operation between an A-IoT reader and a device proposed in the present disclosure are described.

[0276] [A-IoT Device Operation]

[0277] 1. Receive a PRDCH message containing monitoring window setting information from the base station / Reader.

[0278] In addition to D2R-specific resource information separated into time / frequency domains required for D2R transmission (e.g., Msg1), the PRDCH message may include at least one of the following information.

[0279] o The above PRDCH message may be an A-IoT paging message or an R2D control information message.

[0280] - In addition, it can be transmitted via PHY control information or MAC PDU (e.g., CE).

[0281] o The following monitoring window configuration information may be included.

[0282] - Processing time information: T Reference_time 1 , T Reference_time 1 , T D2R_min #n , T D2R #n , T D2R_max #n , T R2D_min #n , T R2D #n , T R2D_max #n

[0283] - α: Offset time between the initial Msg2 monitoring window and the (Re-)Msg2 monitoring window, or time offset information between (re)Msg2 / Msg3Feedback and (Re)Msg2 / Msg3Feedback.

[0284] - k: Counter information for the maximum number of monitoring cycles of the device

[0285] 2. The Device transmits Msg1.

[0286] In the case of CFRA, Msg1 is transmitted through the allocated dedicated scheduling resource. Or;

[0287] In the case of CBRA, one of the resources and access occasions classified by the time / frequency domain included in PRDCH is randomly occupied to transmit Msg1.

[0288] 3. The Device performs monitoring based on the monitoring window setting information within the received PRDCH message.

[0289] The device T after Msg1 transmission is complete D2R_min When it reaches, (initial)Msg2 starts monitoring.

[0290] At this time, the timer starts according to the monitoring window timer setting option.

[0291] 4. The Device receives (re-)Msg2 or Msg3 feedback information.

[0292] Upon receiving the above information, the monitoring window timer terminates.

[0293] o After the monitoring window timer expires, prepare to send Msg3.

[0294] (Re-)Receive Msg2: Send Msg3.

[0295] Msg3 Receive feedback information: Send Msg2 Resend request message.

[0296] [Reader / Base Station Operation]

[0297] 1. Send a PRDCH message containing monitoring window setting information to the device.

[0298] In addition to D2R-specific resource information separated into time / frequency domains required for D2R transmission (e.g., Msg1), the PRDCH message may include at least one of the following information.

[0299] o The above PRDCH message may be an A-IoT paging message or an R2D control information message.

[0300] - In addition, it can be transmitted via PHY control information or MAC PDU (e.g., CE).

[0301] o The following monitoring window configuration information may be included.

[0302] - Processing time information: T Reference_time 1 , T Reference_time 1 , T D2R_min #n , T D2R #n , T D2R_max #n , T R2D_min #n , T R2D #n , T R2D_max #n

[0303] - α: Offset time between the initial Msg2 monitoring window and the (Re-)Msg2 monitoring window, or time offset information between (Re)Msg2 / Msg3Feedback and (Re)Msg2 / Msg3Feedback.

[0304] - k: Counter information for the maximum number of monitoring cycles of the device

[0305] 2. Interval [T R2D_min #n , T R2D_max #n After receiving Msg1 in ], minimum T D2R_min #1 Send initial Msg2 after the value.

[0306] 3. After sending Msg2, T R2D_min #1 Expect to receive Msg3 after the value.

[0307] 4. If Msg3 is not received, send Re-Msg2 or Msg3 Feedback information.

[0308] If the Reader knows that the device has successfully received (initial)Msg2, it transmits Msg3 feedback information.

[0309] If the Reader is unaware of the device's (initial)Msg2 reception failure / success, it sends re-Msg2 or Msg3 feedback.

[0310] The present disclosure provides an ON / OFF-based monitoring window configuration method for efficiently receiving one or more R2D messages (e.g., (Re-)Msg2 or Msg3 Feedback (ACK / NACK)) retransmitted by a reader when devices performing random access fail to receive Msg2 or fail to transmit Msg3. Through the present disclosure, the device can complete the random access procedure energy-efficiently by periodically performing monitoring operations in an ON / OFF manner to receive retransmitted R2D messages.

[0311] With respect to the aforementioned embodiments, each embodiment is included within the scope of the invention according to the present disclosure not only in independent cases but also in all cases comprising combinations of embodiments.

[0312]

[0313] Hereinafter, the configuration of an Ambient IoT terminal and a reader device capable of performing some or all of the embodiments described with reference to FIGS. 1 to 24 will be described with reference to the drawings. The foregoing description may be omitted to avoid redundant descriptions, and in such cases, the omitted content may be applied substantially identically to the following description, provided that it does not contradict the technical concept of the invention.

[0314] FIG. 25 is a diagram showing the configuration of an Ambient IoT terminal (2500) according to another embodiment.

[0315] Referring to FIG. 25, an Ambient IoT terminal (2500) according to another embodiment includes a transmitter (2520), a receiver (2530), and a control unit (2510) that controls the operation of the transmitter and the receiver.

[0316] The control unit (2510) controls the overall operation of the terminal (2500) according to a method for performing a random access procedure necessary to perform the embodiments of the present disclosure described above.

[0317] The control unit (2510) can receive resource information for transmitting a first message (Msg1), terminal-specific monitoring window configuration information, and maximum monitoring count information from a reader device. Here, the monitoring window configuration information may include offset information between consecutive retransmission message monitoring windows, and the maximum monitoring count information may indicate the maximum number of operations of a periodic monitoring window.

[0318] Afterwards, the control unit (2510) can transmit a first message through a selected time domain resource among the time domain resources included in the resource information.

[0319] After the first message is transmitted, the control unit (2510) can monitor the second message (Msg2), the retransmitted second message, or the third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the selected time domain resource and offset information included in the monitoring window configuration information.

[0320] Specifically, a periodic on / off type monitoring window may be initiated at the expected reception timing of a second message derived from a selected time domain resource or at specific times when a certain time has elapsed according to offset information from the point in time when the previous monitoring window ended.

[0321] The control unit (2510) can stop the timer of the monitoring window when at least one of the second message, the retransmitted second message, or the third message feedback is received from the reader device within the monitoring window.

[0322] After the timer is stopped, the control unit (2510) can control the transmitter to transmit a subsequent message to the reader device based on the reception result according to monitoring. Specifically, the control unit (2510) can transmit a third message (Msg3) when a second message to be retransmitted is received within the monitoring window, and transmit a request to retransmit the second message when feedback from the third message is received within the monitoring window.

[0323] On the other hand, if the control unit (2510) does not receive any of the second message, the retransmitted second message, or the third message feedback until the number of times periodic on / off monitoring is performed reaches the maximum value according to the maximum monitoring count information, the control unit (2510) may determine that the random access procedure has failed and wait for the next paging message. Alternatively, according to one example, if the second message (Msg2) is not received until the number of times monitoring is performed on an R2D message including the second message (Msg2), the retransmitted second message, or the third message feedback (Msg3 Feedback) message reaches the maximum value according to the maximum monitoring count information, the Ambient IoT terminal may determine that the random access procedure has failed and be configured to wait for the next paging message. That is, even if other messages are received, if the second message is not received, the random access procedure may be determined to have failed.

[0324] According to this, a method and device for performing a random access procedure in an ambient IoT environment can be provided. In addition, an energy-efficient random access procedure can be performed with minimal power consumption through ON / OFF-based periodic monitoring operations.

[0325] FIG. 26 is a drawing showing the configuration of a reader device (2600) according to another embodiment.

[0326] Referring to FIG. 26, a reader device (2600) according to another embodiment includes a transmitter (2620), a receiver (2630), and a control unit (2610) that controls the operation of the transmitter and the receiver.

[0327] The control unit (2610) controls the operation of the overall reader device (2600) according to a method for performing a random access procedure necessary to perform the embodiments of the present disclosure described above. The transmitting unit (2620) transmits R2D messages, etc. to an Ambient IoT terminal through a predetermined channel. The receiving unit (2630) receives D2R messages, etc. from the Ambient IoT terminal through a predetermined channel.

[0328] The control unit (2610) can transmit resource information for transmitting a first message (Msg1) to an Ambient IoT terminal, monitoring window configuration information per terminal, and maximum monitoring count information. Here, the monitoring window configuration information may include offset information between consecutive retransmission message monitoring windows, and the maximum monitoring count information may indicate the maximum number of periodic monitoring window operations to be performed by the Ambient IoT terminal.

[0329] Afterwards, the control unit (2610) can receive a first message through a selected time domain resource among the time domain resources included in the resource information.

[0330] After receiving the first message, the control unit (2610) can transmit a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the offset information included in the selected specific time domain resource and monitoring window configuration information.

[0331] Specifically, a periodic on / off type monitoring window can be initiated at intervals corresponding to the expected transmission timing of the second message derived from the selected time domain resource or at specific times according to offset information from the point in time when the previous monitoring window ended.

[0332] Additionally, the retransmission of the second message or the third message feedback may be transmitted when the control unit (2610) determines that the reception of the third message has failed within the interval where the reception of the third message is expected after the second message has been transmitted.

[0333] After the transmission operation, the control unit (2610) can receive a subsequent message from the Ambient IoT terminal. Specifically, the control unit (2610) can receive a third message (Msg3) when it transmits a second message for retransmission, and can receive a second message retransmission request message when it transmits feedback for the third message.

[0334] On the other hand, the control unit (2610) may determine that the random access procedure of the Ambient IoT terminal has failed if the number of times a retransmitted second message or third message feedback is transmitted according to a periodic on / off type monitoring window reaches a maximum value according to the maximum monitoring count information. If the procedure is determined to have failed, the control unit (2610) may initiate a new paging procedure in the next paging round to induce a new connection of the Ambient IoT terminal.

[0335] According to this, a method and device for performing a random access procedure in an ambient IoT environment can be provided. In addition, an energy-efficient random access procedure can be performed with minimal power consumption through ON / OFF-based periodic monitoring operations.

[0336] The aforementioned embodiments may be supported by standard documents disclosed in at least one of the wireless access systems IEEE 802, 3GPP, and 3GPP2. That is, steps, configurations, and parts in the embodiments that are not described to clearly reveal the technical concept may be supported by the aforementioned standard documents. Furthermore, all terms disclosed in this specification may be explained by the standard documents disclosed above.

[0337] The embodiments described above may be implemented through various means. For example, the embodiments may be implemented by hardware, firmware, software, or a combination thereof.

[0338] In the case of implementation by hardware, the method according to the embodiments may be implemented by one or more ASICs (Application Specific Integrated Circuits), DSPs (Digital Signal Processors), DSPDs (Digital Signal Processing Devices), PLDs (Programmable Logic Devices), FPGAs (Field Programmable Gate Arrays), processors, controllers, microcontrollers, or microprocessors.

[0339] In the case of implementation by firmware or software, the method according to the embodiments may be implemented in the form of a device, procedure, or function that performs the functions or operations described above. Software code may be stored in a memory unit and executed by a processor. The memory unit may be located inside or outside the processor and may exchange data with the processor by various means already known.

[0340] Additionally, terms such as "system," "processor," "controller," "component," "module," "interface," "model," or "unit" described above may generally refer to computer-related entities, hardware, combinations of hardware and software, software, or running software. For example, the aforementioned components may be, but are not limited to, processes driven by a processor, processors, controllers, control processors, objects, execution threads, programs, and / or computers. For example, both the application running on the controller or processor and the controller or processor may be components. One or more components may reside within a process and / or execution thread, and the components may be located on a single device (e.g., a system, a computing device, etc.) or distributed across two or more devices.

[0341] The foregoing description is merely an illustrative explanation of the technical concept of the present disclosure, and those skilled in the art to which the present disclosure pertains may make various modifications and variations within the scope of the essential characteristics of the technical concept. Furthermore, since these embodiments are intended to explain, not limit, the scope of the technical concept is not limited by these embodiments. The scope of protection of the present disclosure shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present disclosure.

[0342]

[0343] CROSS-REFERENCE TO RELATED APPLICATION

[0344] This patent application claims priority pursuant to Section 119(a) of the U.S. Patent Act (35 USC § 119(a)) to Korean Patent Application No. 10-2025-0040626 filed on March 28, 2025, all of which are incorporated by reference into this patent application. Furthermore, this patent application claims priority in countries other than the United States for the same reasons as above, all of which are incorporated by reference into this patent application.

Claims

In a method for an ambient IoT terminal to perform a random access procedure, A step of receiving resource information for transmitting a first message (Msg1), terminal-specific monitoring window configuration information, and maximum monitoring count information from a reader device; A step of transmitting the first message through a selected time domain resource among the time domain resources included in the above resource information; A step of monitoring a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the selected time domain resource and offset information included in the monitoring window configuration information; and A method comprising the step of transmitting a subsequent message to the reader device based on the reception result according to the above monitoring. In Article 1, The step of transmitting the above-mentioned subsequent message is, If the second retransmission message is received within the monitoring window, a third message (Msg3) is transmitted, and A method comprising the step of transmitting a second message retransmission request when the third message feedback is received within the monitoring window. In Article 1, The above monitoring step is, A method comprising the step of stopping a timer of a monitoring window when at least one of the second message, the retransmitted second message, or the third message feedback is received from the reader device within the monitoring window. In Article 1, A method further comprising the step of determining that the random access procedure has failed and waiting for the next paging message when none of the second message, the retransmitted second message, or the third message feedback is received until the number of times the periodic on / off type monitoring is performed reaches a maximum value according to the maximum monitoring count information. In Article 1, The above-mentioned periodic on / off type monitoring window is, A method initiated at each point in time when a specific time according to the offset information has elapsed from the time when the previous monitoring window ended, or the expected reception timing of the second message derived from the selected time domain resource. In a method for a reader device to perform a random access procedure, A step of transmitting resource information for transmitting a first message (Msg1) to an Ambient IoT terminal, terminal-specific monitoring window configuration information, and maximum monitoring count information; A step of receiving the first message through a selected time domain resource among the time domain resources included in the above resource information; A step of transmitting a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the selected specific time domain resource and offset information included in the monitoring window configuration information; and A method comprising the step of receiving a subsequent message from the above Ambient IoT terminal. In Article 6, The step of receiving the above subsequent message is, When the above retransmission second message is transmitted, the third message (Msg3) is received, and A method comprising the step of receiving a second message retransmission request message when the third message feedback is transmitted. In Article 6, The above retransmitted second message or the above third message feedback is, A method transmitted when it is determined that the reception of the third message has failed within the interval where the reception of the third message is expected after the second message has been transmitted. In Article 6, A method further comprising the step of determining that the random access procedure of the Ambient IoT terminal has failed when the subsequent message is not received until the number of times the retransmitted second message or the third message feedback is transmitted according to the periodic on / off type monitoring window reaches a maximum value according to the maximum monitoring count information. In Article 6, The above-mentioned periodic on / off type monitoring window is, A method initiated at intervals of specific time according to offset information from the time when the previous monitoring window ended, or the expected transmission timing of the second message derived from the selected time domain resource. In an Ambient IoT terminal performing a random access procedure, Transmitter; Receiver; and It includes a control unit that controls the operation of the transmitting unit and the receiving unit, and The above control unit is, Receive resource information for transmitting the first message (Msg1), terminal-specific monitoring window configuration information, and maximum monitoring count information from a reader device, and Transmitting the first message through a selected time domain resource among the time domain resources included in the above resource information, and Monitoring a second message (Msg2), a retransmitted second message, or a third message feedback (Msg3 Feedback) within a periodic ON / OFF type monitoring window determined based on the selected time domain resource and offset information included in the monitoring window configuration information, and A terminal that transmits a subsequent message to the reader device based on the reception result according to the above monitoring. In Article 11, The above control unit is, If the second retransmission message is received within the monitoring window, a third message (Msg3) is transmitted, and A terminal that transmits a second message retransmission request when the third message feedback is received within the monitoring window. In Article 11, The above control unit is, A terminal that stops the timer of the monitoring window when at least one of the second message, the retransmitted second message, or the third message feedback is received from the reader device within the monitoring window. In Article 11, The above control unit is, A terminal that determines that the random access procedure has failed and waits for the next paging message when none of the second message, the retransmitted second message, or the third message feedback is received until the number of times the periodic on / off type monitoring is performed reaches the maximum value according to the maximum monitoring count information. In Article 11, The above-mentioned periodic on / off type monitoring window is, A terminal that is initiated at every point in time when a specific time according to the offset information has elapsed from the time when the previous monitoring window ended, or the expected reception timing of the second message derived from the selected time domain resource.

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