Method of a mobile device, method of a reader device, mobile device and reader device

Abstract

A method performed by a mobile device is described within comprises triggering a random access procedure by receiving a paging message, the method comprising receiving, from a reader device, a paging message including identity information indicating a transaction of the random access procedure determining that the mobile device has been selected for triggering the random access procedure in a case where the identity information is different from previous identity information stored by the mobile device, or a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

Description

METHOD OF A MOBILE DEVICE, METHOD OF A READER DEVICE, MOBILE DEVICE AND READER DEVICE

[0001] The present disclosure relates to a communication system and to parts thereof.

[0002] The disclosure has particular but not exclusive relevance to wireless communication systems and devices thereof operating according to the 3rd Generation Partnership Project (3GPP) standards, equivalents, or derivatives thereof (including Long Term Evolution (LTE)-Advanced, Next Generation or 5G networks, future generations, and beyond). The present disclosure in particular, but not exclusively, relates to paging procedures between 'Ambient' internet-of-things (A-IoT) devices and an A-IoT device reader for triggering, and performing, random access procedures between the A-IoT devices and the A-IoT device reader.

[0003] Earlier developments of the 3GPP standards were referred to as the Long-Term Evolution (LTE) of Evolved Packet Core (EPC) network and Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN), also commonly referred as '4G'. More recently, the term '5G' and 'new radio' (NR) is used to refer to an evolving communication technology that supports a variety of applications and services. Various details of 5G networks are described in, for example, the 'NGMN 5G White Paper' V1.0 by the Next Generation Mobile Networks (NGMN) Alliance, which document is available from https: / / www.ngmn.org / 5g-white-paper.html. 3GPP intends to support 5G by way of the so-called 3GPP Next Generation (NextGen) radio access network (RAN) and the 3GPP NextGen core network.

[0004] Under the 3GPP standards, a NodeB (or an eNB in LTE, and gNB in 5G) is the radio access network (RAN) node (or simply 'access node', 'access network node' or 'base station') via which communication devices (user equipments or 'UEs') connect to a core network and communicate with other communication devices or remote servers. For simplicity, the present application may use the term access network node, RAN node (or simply RAN) or base station to refer to any such access nodes.

[0005] For simplicity, the present application will use the term mobile device, user device, UE, or IoT device, to refer to any communication device that is able to connect to the core network via one or more base stations. Although the present application may refer to mobile devices in the description, it will be appreciated that the technology described can be implemented on any communication devices (mobile and / or generally stationary) that can connect to a communication network for sending / receiving data, regardless of whether such communication devices are controlled by human input or software instructions stored in memory. An IoT device may, for example, be any UE equipped with appropriate electronics, software, sensors, network connectivity, and / or the like, which enable these devices to collect and exchange data with each other and with other communication devices. IoT devices may, for example, be in the form of automated equipment that may operate without requiring human supervision or interaction.

[0006] In the current 5G architecture, the base station structure may be split into two or more parts. In some RAN implementations there are two parts, known as the Central Unit (CU or gNB-CU) - sometimes referred to as a 'control unit' - and the Distributed Unit (DU or gNB-DU), connected by an F1 interface. This enables the use of a 'split' architecture in which the typically 'higher' CU layers (for example, but not necessarily or exclusively, Packet Data Convergence Protocol (PDCP) and Radio Resource Control (RRC) layers) and the, 'lower' DU layers (for example, but not necessarily or exclusively, Radio Link Control (RLC), Media (sometimes referred to as 'Medium') Access Control (MAC), and Physical (PHY) layers) are separated between a particular CU, and one or more Dus that are connected to and controlled by that CU via the F1 interface. Thus, for example, the higher layer CU functionality for a number of base stations may be implemented centrally (for example, by a single processing unit, or in a cloud-based or virtualised system), whilst retaining the lower layer DU functionality locally separately for each base station.

[0007] In 5G, core network entities comprise logical nodes (or 'functions') including control plane functions (CPFs) and one or more user plane functions (UPFs). The CPFs include, amongst other things, one or more Access and Mobility Management Functions (AMFs), a session management function (SMF), an Authentication Server Function (AUSF), a Unified Data Management (UDM) entity for managing user specific data, a Policy Control Function (PCF), an Application Function (AF), a Security Anchor Function (SEAF), an Authentication credential Repository and Processing Function (ARPF), and / or the like. The AMF generally corresponds to the MME in 4G and performs many of the functions performed by the MME. Each UPF combines functionality of both the S-GW and P-GW - specifically user plane functionality of the S-GW (SGW-U) and user plane functionality of the P-GW (PGW-U). The SMF provides session management functionality (that formed part of MME functionality in 4G). The SMF also combines the some of the functionality provided by the S-GW and P-GW - specifically control plane functionality of the S-GW (SGW-C) and control plane functionality of the P-GW (PGW-C). The SMF also allocates IP addresses to each UE.

[0008] When a UE wishes to access a cell (and / or a beam in the case of 5G) it may attempt to access that cell and / or beam using a random access (RACH) procedure that historically involved four distinct steps. More recently, a simplified access procedure has been developed by which a UE may attempt to access that cell and / or beam using a two-step RACH procedure. Both the four-step and two-step RACH procedures are well known to those skilled in the art.

[0009] In summary, the four-step procedure typically involves the UE selecting random access resources (including, for example, a preamble) that it uses to initiate the RACH procedure. The UE sends the selected preamble in a first message ('Msg1') to a base station over a physical random access channel (PRACH). In response, the base station responds with a random access response (RAR) (or 'Msg2'). The RAR indicates reception of the preamble and includes, amongst other things, an uplink grant field indicating resources to be used in the uplink for a physical uplink shared channel (PUSCH). The UE 3 then sends a third message ('Msg3') to the network over a physical uplink shared channel (PUSCH) based on the information in the RAR. The specific message sent by the UE in this step, and the content of the message, depends on the context in which the random access procedure is being used. For initial RRC connection setup, for example, Msg3 typically comprises an RRC Setup request or similar message carrying a temporary randomly generated UE identifier. The network responds with a fourth message ('Msg4') which carries the randomly generated UE identifier received in Msg3 for contention purposes to resolve any collisions between different UEs using the same preamble sequence. When successful, Msg4 also transfers the UE to a connected state.

[0010] As those skilled in the art will appreciate, while a contention based random access (CBRA) procedure is described, a non-contention based (or 'contention free') procedure may also be used, e.g., in which a dedicated preamble is assigned by the base station to the UE.

[0011] The two-step procedure is similar in terms of the information transferred but involves one UE to base station message ('MsgA') and one base station to UE message ('MsgB'). MsgA, in effect, combines Msg1 and Msg 3 of the four-step procedure, and MsgB, in effect, combines Msg2 and Msg4 of the four-step procedure.

[0012] It will be appreciated that random access procedures such as those mentioned above may also be used in other contexts including, for example, handover, connection reestablishment, requesting UL scheduling where no dedicated resource for a scheduling-request has been configured for the UE, etc.

[0013] Recently, IoT has attracted much attention in the wireless communication world, and as IoT develops and grows, more 'things' are expected to be interconnected to improve productivity efficiency and increase the comforts of life. In this vein efforts have been made to try to reduce the size, complexity, and power consumption of IoT devices to enable the deployment of tens or even hundreds of billions of IoT devices for various applications. Typically, such IoT devices are powered by batteries that need to be replaced or recharged manually. Thus, as the number of IoT devices deployed grows apace, there is an increasingly negative impact from such devices as the need to replace them leads to increasingly high maintenance costs, serious environmental issues, and even safety hazards for some use cases, for example, for the use of wireless sensors in electrical power, and petroleum industries.

[0014] <Ambient IoT> 　　'Ambient' IoT attempts to address some of the above issues and relies on ultra-low complexity devices with ultra-low power. Such ambient IoT devices (also herein referred to simply as an IoT device for simplicity) may be categorised as follows: -　　Type A devices: Any ambient IoT device that has no means of energy storage and no independent signal generation / amplification capabilities. Such devices rely on backscatter communications (described below) to communicate with other devices. -　　Type B devices: Any ambient IoT device that has means of energy storage but no independent signal generation capabilities. Such devices similarly rely on backscatter communications (described below) to communicate with other devices. However, beneficially they can use their stored energy to assist in those backscattering communications. For example, the device can use its stored energy to amplify backscattered signals. -　　Type C devices: Any ambient IoT device that has means of energy storage and independent signal generation, i.e., the device has active radio frequency (RF) components that can generate signals for transmission. Typically, such type C devices are much reduced capabilities compared to a non-ambient IoT device.

[0015] Typically, type A, B, and C devices each have an initial sampling frequency offset (SFO) up to 10Xppm (where the value of X is still to be agreed but may, for example, be 4 or 5).

[0016] Typically, type A, B, and C devices each have their own set of power consumption targets, complexity targets, latency targets, data rate targets, and the like.

[0017] For example, the power consumption target for type A devices during transmitting / receiving is typically set to less than or equal to 1 microwatts (μW), or less than or equal to 10 μW, while for type C devices the power consumption target during transmitting / receiving is typically set to a value between 1 milliwatt (mW) and 10 mW. The power consumption target during transmitting / receiving for type B devices is typically set with reference to the power consumption targets of the type A and C devices. For example, typically, the power consumption target during transmitting / receiving for type B devices is either i) much greater than that of type A devices but less than that of type C devices, or ii) greater than or equal to that of type A devices but less than that of type C devices.

[0018] With respect to data rate targets, for type A, B, and C devices, the user experienced maximum data rate for UL and DL is not less than 5 kbps and the user experienced minimum data rate for UL and DL is not less than 0.1 kbps. Furthermore, with respect to the data being transmitted on the UL and DL a design target of 1000 bits has been sent for the maximum message size that may be transmitted and / or received by type A, B, and C devices.

[0019] With respect to complexity targets, type A devices typically have a target comparable to that set out in International Radio Frequency Identification (RFID) Standards International Organization for Standardization (ISO) 18000-6C (equivalent to Electronic Product Code (EPC), global Class 1 (C1), Generation 2 (G2) or 'EPC C1G2' for short), while type C devices typically have a complexity target in orders of magnitude lower than the complexity of narrowband-(NB-)IoT. The complexity target for type B devices is typically set with reference to the complexity targets of the type A and C devices. For example, typically the complexity target of type B devices is greater than the complexity target for type A devices but less than the complexity target for type C devices.

[0020] With respect to latency targets, for type A, B, and C devices, typically a one-way end-to-end maximum latency target is set of between 1 second (shorter latency target) to 10 seconds (longer latency target). The data rate targets type A, B, and C devices are typically set at a maximum of no less than 5 kilobits-per-second (kbps), and minimum of no less than 0.1 kbps for both uplink (UL) and downlink (DL) transmission, with a maximum message size target for such transmissions of approximately 1000 bits i.e., it is aimed for ambient IoT devices to receive and transmit a maximum of approximately 1000 bits per message.

[0021] Typically, where such ambient IoT devices are implemented in a communication network (also referred to as an ambient IoT network) a maximum connection density target may also be set to ensure optimal performance of the network. Typically, such maximum connection density is set at 150 devices per 100 m2for indoor scenarios, and 20 devices per 100 m2for outdoor scenarios.

[0022] Ambient IoT networks may be configured to have any one of several possible connectivity topologies and may be deployed in several different ways. These topologies include: -　　Topology 1 in which an ambient IoT device reader (in this example a base station or RAN node) and ambient IoT device communicate with one another directly (including the possibility that the base station that transmits to the ambient IoT device is different to the base station that receives from the ambient IoT device). This topology may, therefore, need to support full duplex operation at the base station to enable backscatter communication. This can be a significant challenge if an incoming RF signal (known as an 'unmodulated carrier' or 'unmodulated carrier signal'), and reflected signal are within the same radio frequency (RF) band. -　　Topology 2 in which a base station (or RAN node) and ambient IoT device communicate with one another via an ambient IoT device reader in the form of an intermediate / assisting node (which may be a relay, an integrated access and backhaul (IAB) node, another UE, a repeater and / or the like, which is capable of ambient IoT operation). The intermediate node transfers ambient IoT data and / or signalling between base station and the ambient IoT device. Like Topology 1, this topology may require support of full duplex operation at intermediate node and hence faces similar associated challenges. -　　Topology 3 in which the ambient IoT device: receives data / signalling from the base station (or RAN node) directly but transmits data / signalling to the base station indirectly via an assisting node; or transmits data / signalling to the base station (or RAN node) directly but receives data / signalling from the base station indirectly via an assisting node. Accordingly, in this example some IoT device reader functionality is provided by the base station and some IoT device reader functionality is provided by the assisting node. The assisting node may be a relay, an IAB node, another UE, a repeater and / or the like, which is capable of ambient IoT operation. This topology has the benefit that it does not require the base station, or the assisting node, to have full duplex operation. However, the node receiving the reflected signal needs to be able to differentiate between an unmodulated carrier signal and a reflected signal from an ambient IoT device.

[0023] It will be appreciated that for ambient IoT (A-IoT) devices such as those described above to perform communications with an ambient IoT (A-IoT) device reader (e.g., a RAN node / base station and / or intermediate / assisting node), an access procedure (e.g., a RACH-like procedure, or the like) may need to be performed between the A-IoT devices and the A-IoT device reader. Moreover, when the network needs to communicate with an A-IoT device, or a group of A-IoT devices, some form of paging may need to take place to trigger that A-IoT device (or each A-IoT device of a group of A-IoT devices) to initiate a corresponding random access procedure.

[0024] For example, in a basic A-IoT paging and random access procedure the A-IoT random access may be triggered by the A-IoT reader using an appropriate paging like message targeting a single A-IoT device, group of A-IoT devices, or all A-IoT devices covered by the A-IoT device reader. The paging of the target A-IoT devices may need to be repeated over several access / paging rounds in order to reach all the target A-IoT devices. Moreover, the network may wish to initiate another paging targeting different A-IoT devices / A-IoT device groups before an earlier paging has completed. For each paging round, an A-IoT reader may configure multiple random access occasions (RO), among which paged devices can randomly select for uplink transmission.

[0025] NPL 1: 'NGMN 5G White Paper' V1.0 by the Next Generation Mobile Networks (NGMN), available from https: / / www.ngmn.org / 5g-white-paper.html.

[0026] However, there is a risk with this approach that a target A-IoT device may attempt to respond during every paging round even when the target A-IoT device has already successfully performed a random access procedure with the A-IoT device reader. This could potentially be alleviated by appropriate design of the message used to initiate the initial access / paging rounds. However, in this case there is a risk that a target A-IoT device may miss the initial paging round of a paging (e.g., because it is asleep) and thus not respond during a subsequent paging round for the same paging when that A-IoT device is awake depending on appropriate design of the message used to initiate the initial access / paging rounds.

[0027] Moreover, if an A-IoT device reader underestimates an A-IoT device population there is a risk that it may configure the random access performed by the target A-IoT devices in such a way that A-IoT device responses are more likely collide. Such response collisions cause errors, and require additional paging rounds, resulting in increased delays. However, if an A-IoT device reader overestimates an A-IoT device population there is a risk that it may configure the random access performed by the target A-IoT devices in such a way that A-IoT device responses are sparse in time (e.g., due to unnecessarily large back-off times), which also can increase delays.

[0028] It is also generally desirable that A-IoT devices remain asleep / inactive as much as possible. However, the more time that A-IoT devices remain asleep the greater the risk that, in the event that multiple paging rounds are concentrated in a relatively short period that a target A-IoT device will not be awake for any paging round.

[0029] The disclosure aims to provide one or more apparatus and / or one or more associated methods that at least partially addresses or contributes to addressing one or more of the above issues.

[0030] The disclosure has a method performed by a mobile device configured to trigger a random access procedure by receiving a paging message, the method comprising receiving, from a reader device, a paging message including identity information indicating a transaction of the random access procedure determining that the mobile device has been selected for triggering the random access procedure in a case where the identity information is different from previous identity information stored by the mobile device, or a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

[0031] The disclosure has a method performed by a reader device configured to cause a mobile device to trigger a random access procedure by transmitting a paging message, the method comprising transmitting, to a mobile device, a paging message including identity information indicating a transaction of the random access procedure, and wherein the identity information is used by the mobile device in determining that the mobile device has been selected for triggering the random access procedure in a case where the identity information is different from previous identity information stored by the mobile device, or a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

[0032] The disclosure has a mobile device configured to trigger a random access procedure by receiving a paging message, the mobile device comprising means for receiving, from a reader device, a paging message including identity information indicating a transaction of the random access procedure means for determining that the mobile device has been selected for triggering the random access procedure in a case where the identity information is different from previous identity information stored by the mobile device, or a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

[0033] The disclosure has a reader device configured to cause a mobile device to trigger a random access procedure by transmitting a paging message, the reader device comprising means for transmitting, to a mobile device, a paging message including identity information indicating a transaction of the random access procedure, and wherein the identity information is used by the mobile device in determining that the mobile device has been selected for triggering the random access procedure in a case where the identity information is different from previous identity information stored by the mobile device, or a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

[0034] The disclosure has a method performed by a distributed unit of a base station, the method comprising receiving, from a central unit of the base station, a message including information of at least one cell for the at least one cell in the distributed unit to transmit an on-demand synchronizatrion signal / physical broadcast channel (PBCH) block (SSB) of the at least one cell; and determining to activate or deactivate to transmit the on-demand SSB of the at least one cell.

[0035] The various functional means described below that are part of the UE may be provided by a memory and one or more processors that execute instructions stored in the memory. Similarly, the various functional means described below that are part of the access network node may be provided by a memory and one or more processors that execute instructions stored in the memory.

[0036] Various example described below may be implemented by means of a computer program product comprising computer implementable instructions for causing a programmable computer to carry out any of the methods described below. The computer implementable instructions may be provided as a signal or on a tangible computer readable medium.

[0037] Examples of apparatus and methods will now be described, by way of example, with reference to the accompanying drawings in which:

[0038] Fig. 1 illustrates schematically a mobile (cellular or wireless) communication system to which example embodiments of the disclosure may be applied;Fig. 2 illustrates schematically a first connectivity topology that may be used in the communication system of Fig. 1;Fig. 3 illustrates schematically a second connectivity topology that may be used in the communication system of Fig. 1;Fig. 4A illustrates schematically a third connectivity topology that may be used in the communication system of Fig. 1;Fig. 4B illustrates schematically another arrangement of the third connectivity topology of Figure 4A;Fig. 5 illustrates an example A-IoT paging and random access (RA) procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices that may be implemented in the communication system of Fig. 1;Fig. 6A illustrates schematically two different possible paging scenarios relating to the timing of different paging rounds associated with different pagings that may occur in the communication system of Fig. 1;Fig. 6B illustrates schematically two different possible paging scenarios relating to the timing of different paging rounds associated with different pagings that may occur in the communication system of Fig. 1;Fig. 7 another example A-IoT paging and random access (RA) procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices that may be implemented in the communication system of Fig. 1;Fig. 8 illustrates an example set of paging round attempts by different A-IoT devices in accordance with the example A-IoT paging and random access (RA) of procedure of Fig. 7;Fig. 9 illustrates another example A-IoT paging and random access (RA) procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices that may be implemented in the communication system of Fig. 1;Fig. 10 illustrates an example set of paging round attempts by different A-IoT devices in accordance with the example A-IoT paging and random access (RA) of Fig. 9;Fig. 11 illustrates an example of how different RA trigger messages / A-IoT paging messages may overlap with one another in terms of the A-IoT device IDs indicated therein;Fig. 12 illustrates another example A-IoT paging and random access (RA) procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices that may be implemented in the communication system of Fig. 1;Fig. 13 illustrates another example A-IoT paging and random access (RA) procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices that may be implemented in the communication system of Fig. 1;Fig. 14 illustrates another example A-IoT paging and random access (RA) procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices that may be implemented in the communication system of Fig. 1;Fig. 15 illustrates an example timing scheme for the transmission of an appropriate wake-up signal (WUS) to A-IoT devices prior to a paging for triggering an RA procedure with an A-IoT device reader that may be implemented in the communication system of Fig. 1;Fig. 16 illustrates another example timing scheme for the transmission of an appropriate wake-up signal (WUS) to A-IoT devices prior to a paging for triggering an RA procedure with an A-IoT device reader that may be implemented in the communication system of Fig. 1;Fig. 17 is a simplified block schematic illustrating the main components of a UE that may be implemented in the communication system of Fig. 1;Fig. 18 is a simplified block schematic illustrating the main components of an example of a UE comprising an ambient IoT device that may be implemented in the communication system of Fig. 1;Fig. 19 is a simplified block schematic illustrating the main components of an example of a RAN node that may be implemented in the communication system of Fig. 1; andFig. 20 is a simplified block schematic illustrating the main components of an example of an assisting (or intermediate) node that may be implemented in the communication system of Fig. 1.

[0039] <Overview> 　　An exemplary communication system will now be described in general terms, by way of example only, with reference to Figs. 1 to 4.

[0040] Fig. 1 schematically illustrates a mobile ('cellular' or 'wireless') communication system (e.g., communication system 1) to which examples of the present disclosure are applicable.

[0041] In the communication system 1, user equipments (UEs) 3 (3-1, 3-2, 3-3) (e.g., mobile telephones and / or other mobile devices including (ambient) IoT devices) can communicate with each other via a corresponding radio access network (RAN) node 5-1 that operates according to one or more compatible radio access technologies (RATs). In the illustrated example, the RAN node 5-1 comprises a base station operating one or more associated cells 9. Communication via the RAN node 5-1 is typically routed through a core network 7 (e.g., a 5G / 6G / later generations core network or evolved packet core network (EPC)). As those skilled in the art will appreciate however, a base station 5-1 or 'gNB' 5-1 is an example of a RAN node 5-1 only and that the RAN node 5-1 may be any appropriate RAN node 5-1 (e.g., where appropriate the RAN node 5-1 may be a RAN node that operates using a different RAT than NR / 5G).

[0042] As those skilled in the art will appreciate, whilst three UEs 3, and one RAN node 5-1 are shown in Fig. 1 for illustration purposes, the system, when implemented, will typically include other RAN nodes 5-1 and UEs 3.

[0043] In the illustrated example, the UEs 3 include at least one 'ambient' IoT device 3-1 (A-IoT device 3-1) that is capable of performing backscatter communication and a number of other, non-ambient IoT, UEs 3-2, 3-3 (such as smartphones or the like) that communicate in a conventional manner.

[0044] The A-IoT device 3-1 may, for example, be a Type 1, Type 2a, or Type 2b device as described in the introduction. As described in more detail later, depending on the connectivity topology employed, the A-IoT device 3-1 may be configured for uplink (backscatter) communication and / or downlink communication directly with the RAN node 5-1 and / or may be configured for uplink (backscatter) communication and / or downlink communication indirectly via communication (e.g., 'sidelink' or similar communication) with intermediate, or assisting, node 5-2. It will be appreciated that the intermediate, or assisting, node 5-2 may, in effect, be another node of the RAN, a separate RAN or other type of communication node, or another UE that communicates with the A-IoT device 3-1 via an appropriate device-to-device interface (e.g., D2D, sidelink, PC5 or the like). The intermediate, or assisting, node 5-2 may, for example, be a relay node (e.g., a dedicated relay or UE-relay), an integrated access and backhaul (IAB) node, a repeater and / or the like, which is capable of ambient IoT operation including receiving backscatter / reflected signals from, and / or transmitting unmodulated carrier signals to, the A-IoT device 3-1.

[0045] The RAN node 5-1 controls one or more associated cells 9 either directly, or indirectly via one or more other nodes (such as home base stations, relays, remote radio heads, distributed units, and / or the like). It will be appreciated that the RAN node 5-1 may be configured to support both 4G, 5G, 6G and / or later generation, and / or any other 3GPP or non-3GPP communication protocols.

[0046] The RAN node 5-1 may be a distributed base station comprising at least one distributed unit (DU) (e.g., a gNB-DU or the like), and a central unit (CU) (e.g., a gNB-CU or the like). In such a distributed base station the CU employs a separated control plane and user plane and so is, itself, split between a control plane function (CU-CP) and a user plane function (CU-UP) which respectively communicate, with the DU via an appropriate interface (e.g. F1-C interface) and an appropriate interface (e.g. F1-U interface) (together forming an F1 interface (or 'reference point')), and with one another via an appropriate interface (e.g. E1 interface). It will be appreciated that while the DU may include the physical and virtual elements required to provide the functionality of the lower parts of the PHY layer and hence communicate with the UEs 3 over the air interface, the base station may alternatively (or additionally) include one or more separate radio units (RUs) (e.g., providing this functionality of the lower parts of the PHY layer). It will, nevertheless, be appreciated that the RAN node 5-1 may be a base station may of a non-distributed form, for example as an integrated base station 5-1.

[0047] The UEs 3 (and possibly the intermediate or assisting node 5-2 if present) are configured for communication with the RAN node 5-1 via an appropriate air interface (for example a so-called 'Uu' interface and / or the like). It will be appreciated that the A-IoT device 3-1 may, alternatively or additionally, be configured for indirect communication with the RAN node 5-1 via an (air) interface with the intermediate or assisting node 5-2 (if present) and an (air) interface between the intermediate or assisting node 5-2 and the RAN node 5-1. Neighbouring RAN nodes 5-1 may be connected to each other via an appropriate base station to base station interface (such as the so-called 'X2' interface, 'Xn' interface and / or the like - not shown in Fig. 1).

[0048] The core network 7 includes a number of logical nodes (or 'functions') for supporting communication in the communication system 1. In this example, the core network 7 comprises control plane functions (CPFs) 10 and one or more network node entities for the communication of user data (e.g. user plane functions (UPFs) 11). The CPFs 10 include one or more network node entities for the communication of control signalling (e.g. Access and Mobility Management Functions (AMFs) 10-1), one or more network node entities for session management (e.g. Session Management Functions (SMFs) 10-2) and a number of other functions 10-n. Additional functions may include, for example: an Authentication Server Function (AUSF) which facilitates security processes; a Unified Data Management (UDM) entity for managing user specific data (e.g., for access authorization, user registration, and data network profiles); a Policy Control Function (PCF); an Application Function (AF); a Security Anchor Function (SEAF) which is in a serving network and acts as a "middleman" during an authentication process between a UE 3 and its home network; an Authentication credential Repository and Processing Function (ARPF) which maintains the authentication credentials; and / or the like. It will be appreciated that the nodes or functions may have different names in different systems.

[0049] The RAN node 5-1 is connected to the core network nodes via appropriate interfaces (or 'reference points') such as an N2 reference point between the RAN node 5-1 and the AMF 10-1 for the communication of control signalling, and an N3 reference point between the RAN node 5-1 and each UPF 11 for the communication of user data. At least the non-ambient IoT UEs 3 are each connected to the AMF 10-1 via a non-access stratum (NAS) connection over an appropriate reference point (e.g., N1 reference point (analogous to the S1 reference point in LTE)). It will be appreciated, that N1 communication is routed transparently via the RAN node 5-1.

[0050] One or more UPFs 11 are connected to an external data network 21 (e.g., an IP network such as the internet) via an appropriate reference point (e.g., an N6 reference point) for communication of the user data.

[0051] The AMF 10-1 performs mobility management related functions, maintains the NAS connection with at least each non-ambient IoT UE 3-2, 3-3 and manages UE registration. The AMF 10-1 is also responsible for managing paging.

[0052] The SMF 10-2 is connected to the AMF 10-1 via an appropriate reference point (e.g., N11 reference point). The SMF 10-2 provides session management functionality (that formed part of MME functionality in LTE) and additionally combines some control plane functions (provided by the serving gateway and packet data network gateway in LTE). The SMF 10-2 also allocates IP addresses to at least each non-ambient IoT UE 3-2, 3-3. The SMF 10-2 uses user information provided via the AMF 10-1 to determine what session manager would be best assigned to the user. The SMF 10-2 may be considered effectively to be a gateway from the user plane to the control plane of the network. The SMF 10-2 also allocates IP addresses to at least each non-ambient IoT UE 3-2, 3-3.

[0053] Each RAN node 5-1 is also configured for transmission of, and at least the non-ambient IoT UEs 3-2, 3-3 are configured for the reception of, control information and user data via a number of downlink (DL) physical channels and for transmission of a number of physical signals. The DL physical channels correspond to resource elements (REs) carrying information originated from a higher layer, and the DL physical signals are used in the physical layer and correspond to REs which do not carry information originated from a higher layer.

[0054] The physical channels may include, for example, a physical downlink shared channel (PDSCH), a physical broadcast channel (PBCH), and a physical downlink control channel (PDCCH). The PDSCH carries data sharing the PDSCH's capacity on a time and frequency basis. The PDSCH can carry a variety of items of data including, for example, user data, UE-specific higher layer control messages mapped down from higher channels, system information blocks (SIBs), and paging. The PDCCH carries downlink control information (DCI) for supporting a number of functions including, for example, scheduling the downlink transmissions on the PDSCH and also the uplink data transmissions on a physical uplink shared channel (PUSCH). The PBCH provides at least the non-ambient IoT UEs 3-2, 3-3 with the Master Information Block (MIB). It also, in conjunction with the PDCCH, supports the synchronisation of time and frequency, which aids cell acquisition, selection and re-selection.

[0055] The DL physical signals may include, for example, reference signals (RSs) and synchronization signals (SSs). A reference signal (sometimes known as a pilot signal) is a signal with a predefined special waveform known to both the UE 3 and the RAN node 5-1. The reference signals may include, for example, cell specific reference signals, UE-specific reference signal (UE-RS), downlink demodulation signals (DMRS), and channel state information reference signal (CSI-RS).

[0056] Similarly, at least the non-ambient IoT UEs 3-2, 3-3 are configured for transmission of, and the RAN node 5-1 is configured for the reception of, control information and user data via a number of uplink (UL) physical channels corresponding to REs carrying information originated from a higher layer, and UL physical signals which are used in the physical layer and correspond to REs which do not carry information originated from a higher layer. The physical channels may include, for example, the PUSCH, a physical uplink control channel (PUCCH), and / or a physical random access channel (PRACH). The UL physical signals may include, for example, demodulation reference signals (DMRS) for a UL control / data signal, and / or sounding reference signals (SRS) used for UL channel measurement.

[0057] Moreover, at least the non-ambient UEs 3-2, 3-3 and the RAN node 5-1 are mutually configured for performing a random access channel (RACH) procedure for those UEs 3-2, 3-3 to access the network. Specifically, on detection and selection of a cell (and / or a beam in the case of 5G) a UE 3 is able to attempt access to that cell and / or beam using an initial radio resource control (RRC) connection setup procedure comprising a random access procedure with the RAN node 5-1.

[0058] Prior to attempting initial access, at least a non-ambient IoT UE 3-2, 3-3 will choose random access resources (including, for example, a preamble) to use to initiate the RACH procedure. The UE 3 sends the selected preamble (e.g., in 'Msg1') to the RAN node 5-1 over a physical random access channel (PRACH) for initiating the process to obtain synchronization in the uplink (UL). In response, the RAN node 5-1 responds with a random access response (RAR) (or 'Msg2'). The RAR indicates reception of the preamble and includes: a timing advance (TA) command for adjusting the transmission timing of the UE 3 based on the timing of the received preamble; an uplink grant field indicating the resources to be used in the uplink for a physical uplink shared channel (PUSCH); a frequency hopping flag to indicate whether the UE 3 is to transmit on the PUSCH with or without frequency hopping; a modulation and coding scheme (MCS) field from which the UE 3 can determine the MCS for the PUSCH transmission; and a transmit power control (TPC) command value for setting the power of the PUSCH transmission. The UE 3 then sends a third message ('Msg3') to the RAN node 5-1 over a physical uplink shared channel (PUSCH) based on the information in the RAR. The specific message sent by the UE 3 in this step, and the content of the message, depends on the context in which the random access procedure is being used. In the example of initial RRC connection setup, however, Msg3 typically comprises an RRC Setup request or similar message carrying a temporary randomly generated UE identifier. The RAN node 5-1 responds with a fourth message ('Msg4') which carries the randomly generated UE identifier received in Msg3 for contention purposes to resolve any collisions between different UEs 3 using the same preamble sequence. When successful, Msg4 also transfers the UE 3 to a connected state.

[0059] At least the non-ambient IoT UEs 3-2, 3-3 and the RAN node 5-1 are also mutually configured for performing a two-step RACH procedure that involves the UE 3-2, 3-3 sending one message ('MsgA') to the RAN node 5-1 and the RAN node 5-1 sending one message ('MsgB') to the UE 3-2, 3-3. MsgA, in effect, combines Msg1 and Msg 3 of the four-step procedure, and MsgB, in effect, combines Msg2 and Msg4 of the four-step procedure.

[0060] While contention-based RACH procedures are described it will be appreciated that a UE 3 and the RAN node 5-1 may also perform a non-contention based (or 'contention free') procedure in which a dedicated preamble is assigned by the RAN node 5-1 to the UE 3. Moreover, the UE 3 and the RAN node 5-1 may perform a two-step RACH procedure.

[0061] At least the non-ambient UEs 3-2, 3-3, and the RAN node 5-1 are mutually configured for performing random access (RA) based small data transmissions (SDTs) as part of a contention based random access (CBRA) procedure (e.g., as described above). Specifically, resources for attempting the RA based SDT may be configured by the RAN node 5-1 to the UE 3-2, 3-3, in a system information message or the like. The UEs 3-2, 3-3, and the RAN node 5-1 may then send the SDT in one of the messages sent from the UE 3-2, 3-3 to the RAN node 5-1 as part of the RA procedure. The RA based SDT may be performed as part of a two-step RACH procedure, or as part of a four-step RACH procedure. In the case of two-step RA the small data payload may be sent in the first step (e.g., with the initial random access message, 'MsgA'). Contrastingly, in the four-step procedure contention resolution may be performed (e.g., based on Msg1 and Msg2) before the small data payload is transmitted with Msg3 (e.g., with an RRC Resume Request or the like). Msg4 may then release the connection (possibly with a suspend indication to move the UE 3-2, 3-3 back into an inactive state) although the procedure may continue with further small data transmissions before the connection is released.

[0062] Each A-IoT device 3-1 may be completely passive or may be active and configured with at least a subset of the functionality of the non-ambient IoT UEs 3-2, 3-3. It will be appreciated that the specific functionality with which the A-IoT device 3-1 is configured is dependent on the type of A-IoT device 3-1 as described above. For example, the A-IoT device 3-1 and RAN node 5-1 and / or intermediate / assisting node 5-2 may be configured for performing a two-step and / or four-step RACH procedure the same as (or similar to) that described above and may be configured for performing SDT as part of the two-step and / or four-step RACH procedure.

[0063] It will, nevertheless, be appreciated that regardless of the non-ambient IoT UE functionality that an A-IoT device 3-1 may be configured with, each A-IoT device 3-1 is respectively configured with A-IoT specific functionality and each RAN node 5-1 is configured with corresponding functionality for communication with A-IoT devices 3-1.

[0064] For example, each RAN node 5-1 is also configured for transmission of, and the A-IoT devices 3-1 are configured for the reception of, control information and data via a physical R2D channel (PRDCH) for R2D communication that will typically carry any higher-layer payload, and any L1 R2D control information (if defined). Similarly, each RAN node 5-1 is also configured for reception of, and the A-IoT devices 3-1 are configured for the transmission of, control information and data via a physical D2R channel (PDRCH) for D2R communication that will typically carry any higher-layer payload, and any L1 D2R control information (if defined).

[0065] <Connectivity Topologies> 　　The A-IoT device 3-1 may form part of an ambient IoT network having any one of the possible connectivity topologies referred to in the introduction and may be deployed in any of several different ways. Possible connectivity topologies and their deployment will now be described in more detail with reference to Figs. 2 to 4.

[0066] Fig. 2 illustrates schematically a first connectivity topology (topology 1) that may be used in the communication system 1.

[0067] As shown in Fig. 2, in topology 1 the functionality of an A-IoT device reader is implemented as part of a RAN node 5-1. An A-IoT device 3-1 and the RAN node 5-1 engage in direct communication with one another (i.e., without the presence of an assisting or intermediate node 5-2). Specifically, as shown, the A-IoT device 3-1 directly and bidirectionally communicates with the RAN node 5-1. The communication 20 (20-1, 20-2) between the RAN node 5-1 and the A-IoT device 3-1 may, for example, include ambient IoT data and / or other ambient IoT signalling (e.g., control signals or the like). The communication 20 between the RAN node 5-1 and the A-IoT device 3-1 may occur over an appropriate air interface such as the NR Uu air interface, a dedicated interface for ambient IoT, or the like.

[0068] In this example, the RAN node 5-1 is responsible for transmission of an unmodulated carrier signal 20-1 to the A-IoT device 3-1. This unmodulated carrier signal is, in turn, modulated and backscattered / reflected by the A-IoT device 3-1, as a backscattered signal 20-2, to the RAN node 5-1. Such transmission of an unmodulated carrier, and receipt of backscattering by the same RAN node (base station) 5-1 may, for example, be supported by topology 1 where full duplex operation is supported at that RAN node 5-1.

[0069] Nevertheless, although not shown in Fig. 2, topology 1 allows for the possibility that the RAN node 5-1 (in this case the 'IoT device reader') transmitting to the A-IoT device 3-1 is a different RAN node 5-1 (IoT device reader) from the RAN node 5-1 (IoT device reader) receiving from the A-IoT device 3-1. For example, a first RAN node 5-1 (IoT device reader) may transmit an unmodulated carrier signal 20-1 to the A-IoT device 3-1, and a second RAN node 5-1 (IoT device reader) may receive a resulting backscattered signal 20-2 from the A-IoT device 3-1. In this scenario backscattering may be supported even where full duplex operation is not supported at either of the RAN nodes 5-1 (IoT device readers).

[0070] Topology 1 may typically be deployed for indoor scenarios, with a type 1, 2a, and / or 2b A-IoT device and the RAN node 5-1 (IoT device reader) being located in an indoor environment. In this scenario the RAN node 5-1 typically supports one or more small cells (e.g., micro-, and pico- cells) used for voice, video, and data transmission, which are designed to provide network coverage to small areas and operate on either licensed frequency division duplex (FDD), licensed time division duplex (TDD), or unlicensed parts of the spectrum.

[0071] Alternatively, topology 1 may be deployed for scenarios where the A-IoT device 3-1 is in an indoor environment but the RAN node 5-1 is located in an outdoor environment. In this case, the RAN node 5-1 may be configured to support one or more small cells (e.g., micro-cells) used for voice, video, and data transmission, which are designed to provide network coverage to small areas and operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum. Alternatively, the RAN node 5-1 may support one or more larger cells (e.g., macro- cells) providing radio coverage to a large area, and that operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum.

[0072] Topology 1 may also be deployed for outdoor scenarios with one or more A-IoT devices 3-1 and the RAN node 5-1 are located in an outdoor environment. In such scenarios the RAN node 5-1 may support one or more small cells (e.g., micro-cells) used for voice, video, and data transmission, which are designed to provide network coverage to small areas and operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum. Alternatively (or additionally), the RAN node 5-1 may support larger cells (e.g., macro- cells) providing radio coverage to a large area, and that operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum.

[0073] This topology may, for example, be appropriate for a situation in which a RAN node 5-1 needs to fetch data (e.g., a meter record, a sensor reading, an error code and / or the like) from the A-IoT device 3-1. The RAN node 5-1 will send an unmodulated carrier signal as a 'stimulus' signal to the A-IoT device 3-1 which will automatically respond with the required data encoded in the resulting backscattered / reflected signal.

[0074] Fig. 3 illustrates schematically a second connectivity topology (topology 2) that may be used in the communication system 1.

[0075] As shown in Fig. 3, in topology 2 the functionality of an IoT device reader is implemented as part of an intermediate node 5-2. Specifically, an A-IoT device 3-1 and a RAN node 5-1 engage in communication with one another via the intermediate node 5-2 (which may also be referred to as an assisting node / IoT device reader) to transfer ambient IoT data and / or signalling between the RAN node 5-1 and the A-IoT device 3-1. It will be appreciated that while the intermediate node 5-2 is depicted in Fig. 3 as being a type of base station, the intermediate node 5-2 may in fact be any one of an IAB node, a UE 3, a repeater, or the like, or any other appropriate device, as described above, that can act as an intermediary between a RAN node 5-1 and an A-IoT device 3-1 and that is capable of supporting ambient IoT signalling.

[0076] In this example, the A-IoT device 3-1 communicates bidirectionally with the intermediate node 5-2, which is located between the A-IoT device 3-1 and RAN node 5-1, and which is able to transfer ambient IoT data and / or signalling between the RAN node 5-1 and the A-IoT device 3-1.

[0077] Specifically, the communication 20-1, 20-2 between the intermediate node 5-2 and the A-IoT device 3-1 may occur over an appropriate air interface. For example, they may communicate over a Uu or a dedicated interface.

[0078] In a first (downlink) direction , a downlink signal may be transmitted from the RAN node 5-1 to the intermediate node 5-2 as part of communication 20-3 between the RAN node 5-1 and the intermediate node 5-2. The downlink signal, once received by the intermediate node 5-2, may trigger transmission of an unmodulated carrier signal 20-1 to the A-IoT device 3-1 (e.g., on a 'sidelink' or similar). The downlink signal may be (or may carry) the unmodulated carrier signal 20-1 that is to be transmitted (e.g. relayed) by the intermediate node 5-2 to the A-IoT device 3-1 or may be a trigger signal for triggering transmission of the unmodulated carrier signal 20-1.

[0079] In a second (uplink) direction , the intermediate node 5-2 is responsible for receiving a modulated backscattered signal 20-2 from the A-IoT device 3-1 (e.g., on a 'sidelink' or similar). Specifically, the uplink communication may comprise a modulated backscattered signal 20-2 from the A-IoT device 3-1 to the intermediate node 5-2 that is transmitted (e.g., on a 'sidelink' or similar) in response to receiving the unmodulated carrier signal 20-1 from the intermediate node 5-2. This modulated backscattered signal 20-2 (or at least the information encoded in it), once received by the intermediate node 5-2, may be relayed / forwarded (transmitted) to the RAN node 5-1 in an uplink signal as part of the communication 20-3 between the intermediate node 5-2 and the RAN node 5-1. The modulated backscattered signal 20-2 may be processed before being relayed by the intermediate node 5-2 to the RAN node 5-1. For example, the modulated backscattered signal 20-2 may be processed by the intermediate node 5-2 to extract information encoded in the modulated backscattered signal, and to encapsulate the extracted information into an appropriate message format (e.g., in accordance with a corresponding application protocol) for communication with the RAN node 5-1. Alternatively, the modulated backscattered signal may itself be processed by the intermediate node 5-2 (without extracting any data encoded in it) to encapsulate it into an appropriate message format (e.g., in accordance with a corresponding application protocol) for communication with the RAN node 5-1.

[0080] Such transmission of an unmodulated carrier, and receipt of backscattering by the same intermediate node 5-2 may, for example, be supported by topology 2 where full duplex operation is supported at that intermediate node 5-2.

[0081] Communication 20-3 between the RAN node 5-1 and the intermediate node 5-2 may occur over any appropriate interface. For example, the RAN node 5-1 and intermediate node 5-2 may communicate over an air interface (such as the Uu interface or the like), for example where the intermediate node 5-2 is a UE 3 (or at least acts like a UE in its communication with the RAN node 5-1). The RAN node 5-1 and intermediate node 5-2 may communicate over a direct base station to base station interface (such as X2 or Xn), for example where the intermediate node 5-2 is a base station (or at least acts like a base station in its communication with the RAN node 5-1). The RAN node 5-1 and intermediate node 5-2 may communicate over an appropriate IAB interface (such as F1), for example where the RAN node 5-1 acts as an IAB donor base station and the intermediate node 5-2 is an IAB node. Nevertheless, the RAN node 5-1 and the intermediate node 5-2 may communicate over a dedicated interface for the purpose of ambient IoT.

[0082] It will be appreciated that the intermediate node 5-2 may be of a type that attempts to demodulate the received backscattered signal for subsequent forwarding of the data to the RAN node 5-1 (e.g., a layer-2 (L2) relay device that attempts to demodulate any layer-1 (L1) signals that it receives). Such an intermediate node may be referred to as be a layer 2 ('L2') type intermediate node 5-2. Nevertheless, the intermediate node 5-2 may be of a type that blindly forwards a received signal without attempting to demodulate it and hence, on receipt of the backscattered signal no attempt is made to demodulate it (e.g., an L1 repeater device or a network-controlled repeater (NCR) node). Such an intermediate node may be referred to as be a layer 1 ('L1') type intermediate node 5-2.

[0083] Topology 2 may be deployed for scenarios with a type 1, 2a, and / or 2b A-IoT device 3-1, in which the A-IoT device 3-1 is in an indoor environment but the RAN node 5-1 is located in an outdoor environment. In this scenario the RAN node 5-1 may support one or more small cells (e.g., micro-cells) used for voice, video, and data transmission, which are designed to provide network coverage to small areas and operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum. Alternatively, the RAN node 5-1 may support one or more larger cells (e.g., macro- cells) providing radio coverage to a large area, and that operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum. In this scenario, the assisting node 5-2 may be located in an indoor or an outdoor environment.

[0084] Topology 2 may also be deployed for indoor scenarios with a type 1, 2a, and / or 2b A-IoT device 3-1, intermediate device 5-2, and RAN node 5-1 are located in an indoor environment. In this scenario the RAN node 5-1 typically supports one or more small cells (e.g., micro-, and pico- cells) used for voice, video, and data transmission, which are designed to provide network coverage to small areas and operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum.

[0085] Topology 2 may also be deployed for outdoor scenarios with a type 1, 2a or 2b A-IoT device 3-1, RAN node 5-1 and intermediate (or assisting) node 5-2 being located in an outdoor environment. In this scenario the RAN node 5-1 may support one or more small cells (e.g., micro-cells) used for voice, video, and data transmission, which are designed to provide network coverage to small areas and operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum. Alternatively, the RAN node 5-1 may support one or more larger cells (e.g., macro- cells) providing radio coverage to a large area, and that operate on either licensed FDD, licensed TDD, or unlicensed parts of the spectrum.

[0086] This topology may, for example, be appropriate for a situation in which the RAN node 5-1 needs to fetch data (e.g., a meter record, a sensor reading, an error code and / or the like) from the A-IoT device 3-1. The RAN node 5-1 will trigger the intermediate node 5-2 to send an unmodulated carrier signal as a 'stimulus' signal to the A-IoT device 3-1 which will automatically respond with the required data encoded in the resulting backscattered / reflected signal. The resulting backscattered / reflected signal (or at least the data encoded in it) will then be forwarded / relayed to the RAN node 5-1.

[0087] Figs. 4A and 4B illustrate schematically a third connectivity topology (topology 3) of a mobile (cellular or wireless) communication system.

[0088] As shown in Figs. 4A and 4B, in topology 3 part of the functionality of an A-IoT device reader is implemented as part of an assisting node 5-2 and part of the functionality of the A-IoT device reader is implemented as part of a RAN node 5-1. Specifically, an A-IoT device 3-1 and the RAN node 5-1 engage in communication with one another via the assisting node 5-2 (which may also be referred to as an intermediate node). It will be appreciated that while the assisting node 5-2 is depicted in Fig. 4A and Fig. 4B as a type of base station, the assisting node 5-2 may in fact be any one of an IAB node, a UE 3, a repeater, or the like, or any other appropriate device that can act as an intermediary between the RAN node 5-1 and the A-IoT device 3-1.

[0089] It will be appreciated that the assisting node 5-2 may be of a type that attempts to demodulate the received backscattered signal for subsequent forwarding of the data to the RAN node 5-1 (e.g., a layer-2 (L2) relay device that attempts to demodulate any layer-1 (L1) signals that it receives). Such an assisting node may be referred to as be a layer 2 ('L2') type assisting node 5-2. Nevertheless, the assisting node 5-2 may be of a type that blindly forwards a received signal without attempting to demodulate it (e.g., an L1 repeater device or a network-controlled repeater (NCR) node) and hence, on receipt of the backscattered signal no attempt is made to demodulate it. Such an assisting node may be referred to as be a layer 1 ('L1') type assisting node 5-2.

[0090] As shown in Fig. 4A, the A-IoT device 3-1 may communicate with the RAN node 5-1 in a downlink direction and the assisting (intermediate) node 5-2 in an uplink direction (e.g., on a 'sidelink' or similar). The communication between the RAN node 5-1 and the A-IoT device 3-1, or the communication between the assisting node 5-2 and the A-IoT device 3-1 respectively may occur over an appropriate air interface. For example, they may communicate over a Uu or dedicated 'sidelink' interface.

[0091] In this example the RAN node 5-1 (base station / cell) is responsible for transmission of an unmodulated carrier signal 20-1 to the A-IoT device 3-1. This unmodulated carrier signal 20-1 may subsequently be modulated and backscattered, as a modulated backscattered signal 20-2, from the A-IoT device 3-1 and received at the assisting node 5-2. That is, the assisting node 5-2 is responsible for receiving the backscattered signal 20-2 from the A-IoT device 3-1. The modulated backscattered signal 20-2 (or at least the information encoded in it), once received by the assisting node 5-2, may be relayed (forwarded / transmitted) to the RAN node 5-1. The modulated backscattered signal may be processed before being relayed / forwarded by the assisting node 5-2 to the RAN node 5-1. For example, the modulated backscattered signal may be processed by the assisting node 5-2 to extract information encoded in the modulated backscattered signal, and to encapsulate the extracted information into an appropriate message format (e.g., in accordance with a corresponding application protocol) for communication with the RAN node 5-1. Alternatively, the modulated backscattered signal may itself be processed by the assisting node 5-2 (without extracting any data encoded in it) to encapsulate it into an appropriate message format (e.g., in accordance with a corresponding application protocol) for communication with the RAN node 5-1.

[0092] The communication 20-3 between the RAN node 5-1 and the assisting node 5-2 occurs over an appropriate interface. For example, the RAN node 5-1 and the assisting node 5-2 may communicate over an air interface (such as the Uu interface or the like), for example where the intermediate node 5-2 is a UE 3 (or at least acts like a UE in its communication with the RAN node 5-1). The RAN node 5-1 and assisting node 5-2 may communicate over an appropriate IAB interface (such as F1), for example where the RAN node 5-1 acts as an IAB donor base station and the intermediate node 5-2 is an IAB node. Nevertheless, the RAN node 5-1 and the assisting node 5-2 may communicate over a dedicated interface for the purpose of ambient IoT. The communication, comprising the modulated backscattered signal 20-2 received at the assisting node 5-2 from the A-IoT device 3-1, also occurs over an appropriate air interface. For example, they may communicate over a Uu or a dedicated interface.

[0093] This topology may, for example, be appropriate for a situation in which the RAN node 5-1 needs to fetch data (e.g., a meter record, a sensor reading, an error code and / or the like) from the A-IoT device 3-1. The RAN node 5-1 will send an unmodulated carrier signal as a 'stimulus' signal to the A-IoT device 3-1 which will automatically respond with the required data encoded in the resulting backscattered / reflected signal sent to the assisting node 5-2 for relaying / forwarding to the RAN node 5-1.

[0094] Alternatively, as shown in Fig. 4B, the A-IoT device 3-1 may communicate with the RAN node 5-1 in an uplink direction and the assisting (intermediate) node 5-2 in a downlink direction (e.g., on a 'sidelink' or similar). The communication between the RAN node 5-1 and the A-IoT device 3-1, and the communication between the assisting node 5-2 and the A-IoT device 3-1, respectively occur over an appropriate air interface. For example, they may communicate over a Uu or dedicated 'sidelink' interface.

[0095] In this example the assisting node 5-2 is responsible for transmission of an unmodulated carrier signal 20-1 to the A-IoT device 3-1. This unmodulated carrier signal 20-1 may be subsequently modulated and backscattered, as a modulated backscattered signal 20-2, from the A-IoT device 3-1 and received at the RAN node 5-1. That is, the RAN node 5-1 (base station / cell) is responsible for receiving the backscattered signal 20-2 from the A-IoT device 3-1. The transmission of the unmodulated carrier signal 20-1 may be triggered by a downlink signal 20-3 received by the assisting node 5-2 from the RAN node 5-1. For example, the downlink signal 20-3 may be (or may carry) the unmodulated carrier signal 20-1 that is to be transmitted (e.g. relayed) by the intermediate node 5-2 to the A-IoT device 3-1 or may be a trigger signal for triggering transmission of the unmodulated carrier signal 20-1.

[0096] This topology may, for example, be appropriate for a situation in which the RAN node 5-1 needs to fetch data (e.g., a meter record, a sensor reading, an error code and / or the like) from the A-IoT device 3-1. The RAN node 5-1 will send an unmodulated carrier signal as a 'stimulus' signal to the A-IoT device 3-1 which will automatically respond with the required data encoded in the resulting backscattered / reflected signal sent to the assisting node 5-2. The resulting backscattered / reflected signal (or at least the data encoded in it) will then be forwarded / relayed to the RAN node 5-1 by the assisting node 5-2.

[0097] Similarly to Fig. 4A, in Fig. 4B the communication 20-3 between the RAN node 5-1 and the assisting node 5-2 occurs over an appropriate interface. For example, the RAN node 5-1 and the assisting node 5-2 may communicate over an air interface (such as the Uu interface or the like), for example where the intermediate node 5-2 is a UE 3 (or at least acts like a UE in its communication with the RAN node 5-1). The RAN node 5-1 and assisting node 5-2 may communicate over an appropriate IAB interface (such as F1), for example where the RAN node 5-1 acts as an IAB donor base station and the intermediate node 5-2 is an IAB node. Nevertheless, the RAN node 5-1 and the assisting node 5-2 may communicate over a dedicated interface for the purpose of ambient IoT. The downlink communication, comprising the unmodulated carrier signal 20-1 sent from the assisting node 5-2 to the A-IoT device 3-1, also occurs over an appropriate air interface. For example, they may communicate over a Uu or a dedicated interface.

[0098] This topology may, for example, be appropriate for a situation in which the RAN node 5-1 needs to fetch data (e.g., a meter record, a sensor reading, an error code and / or the like) from the A-IoT device 3-1. The RAN node 5-1 will trigger the assisting node 5-2 to send an unmodulated carrier signal as a 'stimulus' signal to the A-IoT device 3-1 which will automatically respond with the required data encoded in the resulting backscattered / reflected signal sent to the RAN node 5-1.

[0099] In either scenario (illustrated in Fig. 4A or 4B), backscattering may be supported even if the RAN node 5-1 and / or the assisting node 5-2 do not support full duplex operation.

[0100] <Example Initial Random Access (RA) Procedure> 　　Fig. 5 illustrates an example A-IoT paging and random access (RA) procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices 3-1 that may be implemented in the communication system 1.

[0101] As shown in Fig. 5, there is provided an A-IoT device reader (e.g., a RAN node 5-1, an intermediate / assisting node 5-2, or some other appropriate device) that may wish to communicate with one or more A-IoT devices 3-1. To communicate with the one or more A-IoT devices 3-1, the A-IoT device reader triggers an appropriate RA procedure such as that shown in Fig. 5.

[0102] For example, the A-IoT device reader may decide to initiate the RA procedure with a specific A-IoT device, 3-1, or a specific group of A-IoT devices 3-1 (e.g., one of type A, B, or C A-IoT devices). Having decided to initiate that RA procedure, the A-IoT device 3-1 triggers / initiates a first paging round for a specific paging (e.g., Paging A) that is configured to target the specific A-IoT devices 3-1 (referred to also as target A-IoT devices 3-1) for which the A-IoT device reader has decided to initiate the RA procedure.

[0103] <Paging A: First Round> 　　At step S502a, having decided / determined that it wants to initiate the RA procedure, the A-IoT device reader sends an initial RA trigger message (or an appropriate A-IoT paging message) to the A-IoT device / devices 3-1 to initiate a first paging round of a Paging 'A'.

[0104] The initial RA trigger message / A-IoT paging message may include, for the target A-IoT devices 3-1 for which the A-IoT device reader wishes to trigger the RA procedure, an appropriate indication that the A-IoT device reader has messages, data, or the like for those A-IoT devices 3-1, and that an RA procedure should be triggered between the A-IoT device reader and the target A-IoT devices 3-1.

[0105] It will be appreciated that the initial RA trigger message / A-IoT paging message, sent at step S502a may be configured to trigger an RA procedure between the A-IoT device reader and a single (specific) A-IoT device 3-1, a group of A-IoT devices 3-1, or all A-IoT devices 3-1 under the coverage of the A-IoT device reader (e.g., within the coverage area covered by the A-IoT device reader). For example, the initial RA trigger message / A-IoT paging message sent at step S502a may, by way of example only, include an appropriate indication of the target A-IoT devices 3-1 that need to respond to the initial RA trigger message / A-IoT paging message - i.e., an indication as to which target A-IoT devices 3-1 should perform an RA procedure with the A-IoT device reader (and / or possibly an indication as to which target A-IoT devices 3-1 should not perform an RA procedure with the A-IoT device reader).

[0106] Additionally, the initial RA trigger message / A-IoT paging message sent at step S502a may include an appropriate indication of configured RA occasions (ROs) that can be randomly selected by the target A-IoT devices 3-1 for uplink (UL) (D2R) transmissions to the A-IoT device reader as part of an RA procedure. For example, the initial RA trigger message / A-IoT paging message sent at step S502a may include an appropriate indication of a number ('X') of ROs have been configured by the A-IoT device reader for use by the A-IoT device 3-1 in performing D2R transmissions as part of an RA procedure with the A-IoT device reader.

[0107] Having received the initial RA trigger message / A-IoT paging message at step S502a, each target A-IoT device 3-1 may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown).

[0108] However, due to the risk of a loss of synchronisation between the A-IoT device reader and the A-IoT devices 3-1, rather than the A-IoT device reader indicating timing information associated with the configured ROs to the target A-IoT devices 3-1, each RO may be configured without a predefined start point / position. In this scenario, the start point of each RO may instead be indicated to the A-IoT devices 3-1 individually in an appropriate RO slot indication message / signal (or the like), or an individual RO slot message / signal (or the like) will be sent to A-IoT devices 3-1 before each RO starts. For example, an appropriate RO slot indication message / signal may be sent prior to the start of each RO which may indicate a value i that corresponds to an index of the next RO amongst the plurality of X ROs configured by the A-IoT device reader for use by the A-IoT device 3-1 in performing D2R transmissions as part of an RA procedure with the A-IoT device reader. Alternatively, the appropriate RO slot indication message / signal may be sent prior to the start of each RO may not include the value i; in this case rather than relying on the A-IoT device reader providing the indication (e.g., number) of the next slot, the A-IoT device 3-1 may instead count the received RO slot indication messages / signals to understand which RO slot is indicated as starting next, following that received RO slot indication message / signal.

[0109] Accordingly, at step S504a, following transmission of the initial RA trigger message / A-IoT paging message, the A-IoT device reader may transmit, to the target A-IoT devices 3-1, a first individual RO slot#0 indication message / signal to indicate a start point of the RO slot#0. Alternatively, rather than transmitting a first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 at step S504a, the first individual RO slot#0 may instead be implicitly indicated by the initial RA trigger message / A-IoT paging message sent at step S502a.

[0110] At step S506a, following transmission of the first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 (or following implicit indication of the first individual RO slot#0 in the initial RA trigger message / A-IoT paging message), any of the target A-IoT devices 3-1 that have randomly selected RO slot#0 for performing an RA procedure with the A-IoT device reader performs that RA procedure by sending an appropriate D2R transmission to the A-IoT device reader using the RO slot#0. Any other target A-IoT devices 3-1 that have randomly selected a different RO from slot#0 for performing an RA procedure with the A-IoT device reader will not perform an RA procedure in RO slot#0; instead such A-IoT devices 3-1 wait for the appearance of the RO that they each respectively selected for performing an RA procedure. For example, a target A-IoT device 3-1 that has randomly selected RO slot#4, waits until it receives the 4thRO slot message / signal or the RO slot message / signal which indicates the upcoming RO slot is the 4thRO (e.g., i = 4) and will then perform an RA procedure in RO slot#4.

[0111] After an RA procedure has been attempted, at step S506a, between the A-IoT device reader and one or more of the target A-IoT devices 3-1, the A-IoT device reader and target A-IoT devices 3-1 may engage in one or more further RA cycles (S520). Each further RA cycle involves: the A-IoT device reader providing (at step S508a) a further RO slot indication (e.g., an RO slot#i indication, where i = 1 for the first further cycle, i = 2 for the second further cycle etc.); and one or more target A-IoT devices 3-1 that have randomly selected that indicated RO slot then performs the random access procedure with the A-IoT device reader (at step S510a). For example, if any of the target A-IoT devices 3-1 have randomly selected RO slot#i for performing an RA procedure with the A-IoT device reader, that target A-IoT device 3-1 will perform a RA procedure following receiving RO slot indication for RO slot#i, by sending an appropriate D2R transmission to the A-IoT device reader using the RO slot#i. In another example, if any of the target A-IoT devices 3-1 were unable to successfully complete an RA procedure using an earlier indicated slot / slots then they may attempt access in one of the further RA cycles S520.

[0112] It will be appreciated that the further RA cycles (at S520) may be repeated X times, where X is corresponding to the maximum configured RO slots in this paging round. It will be appreciated that the further RA cycles (at S520) may be repeated more or less than X times, as deemed necessary by the A-IoT device reader.

[0113] <Paging A: Second Round> 　　Following the first paging round of a Paging A (steps S502a to S510a), the A-IoT device reader may initiate, where appropriate, a second paging round of Paging A that is a repeat of the first paging round. For example, where some of the target A-IoT devices 3-1 that the A-IoT device reader wishes to communicate with were unable to successfully perform an RA procedure with the A-IoT device reader (e.g., because they were unable to select / use an appropriate RO slot, because they failed to complete the random access successfully, because they were asleep, or because of some other reason), the A-IoT device reader may attempt to access those A-IoT devices 3-1 again in a second paging round of the Paging A.

[0114] For example, as shown in Fig. 5, at step S502b, the A-IoT device reader sends a follow-up RA trigger message / A-IoT paging message to the A-IoT device / devices 3-1. It will be appreciated that the follow-up RA trigger message / A-IoT paging message may be the same as the initial RA trigger message / initial A-IoT paging message sent at step S502a.

[0115] Following transmission of that follow-up RA trigger message / A-IoT paging message, the procedure at steps S504a to S510a as described above may be repeated within the second paging round of Paging A.

[0116] <Paging B: First Round> 　　Sometime later, at step S512a, having decided / determined that it wants to communicate with different A-IoT devices 3-1 from those targeted by the A-IoT device reader in Paging A, the A-IoT device reader sends a new initial RA trigger message / new A-IoT paging message to those different (new target) A-IoT devices 3-1 to initiate a first paging round of a Paging 'B'. For example, at some later time, the A-IoT device reader may decide that it wishes to communicate with a different type / group / subset of A-IoT devices 3-1 than it communicated with earlier via Paging A, and may trigger a new paging (e.g., Paging B), which is directed toward that different type / group / subset of A-IoT devices 3-1.

[0117] That new initial RA trigger message / new A-IoT paging message may include, for the (new) target A-IoT devices 3-1 for which the A-IoT device reader wishes to trigger the RA procedure, an appropriate indication that the A-IoT device reader has messages, data, or the like for those A-IoT devices 3-1, and that an RA procedure should be triggered between the A-IoT device reader and the target A-IoT devices 3-1.

[0118] It will be appreciated that the initial RA trigger message / A-IoT paging message, sent at step S512a may be configured to trigger an RA procedure between the A-IoT device reader and a single (specific) A-IoT device 3-1, a group of A-IoT devices 3-1, or all A-IoT devices 3-1 under the coverage of the A-IoT device reader (e.g., within the coverage area covered by the A-IoT device reader). For example, the initial RA trigger message / A-IoT paging message sent at step S512a may, by way of example only, include an appropriate indication of the target A-IoT devices 3-1 that need to respond to the initial RA trigger message / A-IoT paging message - i.e., an indication as to which target A-IoT devices 3-1 should perform an RA procedure with the A-IoT device reader (and / or possibly an indication as to which target A-IoT devices 3-1 should not perform an RA procedure with the A-IoT device reader).

[0119] Additionally, the initial RA trigger message / A-IoT paging message sent at step S512a may include an appropriate indication of configured RA occasions (ROs) that can be randomly selected by the target A-IoT devices 3-1 for uplink (UL) (D2R) transmissions to the A-IoT device reader as part of an RA procedure. For example, the initial RA trigger message / A-IoT paging message sent at step S512a may include an appropriate indication of a number ('X') of ROs have been configured by the A-IoT device reader for use by the A-IoT device 3-1 in performing D2R transmissions as part of an RA procedure with the A-IoT device reader.

[0120] Having received the initial RA trigger message / A-IoT paging message at step S512a, each target A-IoT device 3-1 may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown).

[0121] However, due to the risk of a loss of synchronisation between the A-IoT device reader and the A-IoT devices 3-1, rather than the A-IoT device reader indicating timing information associated with the configured ROs to the target A-IoT devices 3-1, each RO may be configured without a predefined start point / position. In this scenario, the start point of each RO may instead be indicated to the A-IoT devices 3-1 individually in an appropriate RO slot indication message / signal (or the like), or an individual RO slot message / signal (or the like) will be sent to A-IoT devices 3-1 before each RO starts. For example, an appropriate RO slot indication message / signal may be sent prior to the start of each RO which may indicate a value i that corresponds to an index of the next RO amongst the plurality of X ROs configured by the A-IoT device reader for use by the A-IoT device 3-1 in performing D2R transmissions as part of an RA procedure with the A-IoT device reader. Alternatively, the appropriate RO slot indication message / signal may be sent prior to the start of each RO may not include the value i; in this case rather than relying on the A-IoT device reader providing the indication (e.g., number) of the next slot, the A-IoT device 3-1 may instead count the received RO slot indication messages / signals to understand which RO slot is indicated as starting next, following that received RO slot indication message / signal.

[0122] Following transmission of that new initial RA trigger message / new initial A-IoT paging message at step S512a, the procedure at steps S504a to S510a as described above are carried out, albeit with respect to Paging B.

[0123] It will be appreciated that the number of different pagings, and the number of paging rounds per paging shown in Fig. 5 is by way of example only, and that any number of different pagings may be scheduled, each with any number of respective paging rounds, to enable the A-IoT device reader to successfully access A-IoT devices 3-1 with which it wishes to communicate.

[0124] <Timing of paging rounds of different pagings> 　　In the example initial RA procedure described above with reference to Fig. 5, the timing of the paging rounds for Paging A and the paging rounds for Paging B may occur at discrete times such that paging rounds associated with Paging B do not occur until all paging rounds associated with Paging A has been completed. For example, as shown in Fig. 6A, transmissions associated with a first set of paging rounds for Paging A and a second set of paging rounds for Paging A may occur such that those transmissions are separated in time (e.g., not interleaved) from transmissions associated with sets of paging rounds for Paging B i.e., Paging B will not start before any on-going paging rounds associated with Paging A have finished. Thus, only one unfinished paging can occur at a time. This may be referred to as concentrated, or non-interleaved, paging.

[0125] Alternatively, in the example initial random access procedure described above with reference to Fig. 5, the timing of the paging rounds for Paging A and the paging rounds for Paging B may occur in an interleaving manner. For example, as shown in Fig. 6B, transmissions associated with a first set of paging rounds for Paging B may occur between transmissions associated with a first set of paging rounds and a second set of paging rounds for Paging A. This may be particularly useful in scenarios where different A-IoT devices 3-1 are awake at different times. For example, the A-IoT device reader may repeat a same paging (e.g., Paging A) in different time windows so as to increase the chances of reaching each target A-IoT device 3-1 with a respective paging.

[0126] For example, as shown in Fig. 6B, a first set of paging rounds associated with Paging A may occur before a first set of paging rounds associated with Paging B, and a second set of paging rounds associated with Paging A may be sent after the first set of paging rounds associated with Paging B - i.e., the first and second sets of paging rounds associated with Paging A are interleaved by the first set of paging rounds associated with Paging B. Additionally (or alternatively), the second set of paging rounds associated with Paging A may be sent a long time after the first set of paging rounds associated with Paging B. This may be referred to as dispersed, or interleaved, paging.

[0127] <A-IoT Paging and Random Access Related Enhancements> 　　Beneficially, as described in more detail later, the communication system 1 is configured to support one or more enhancements for supporting A-IoT paging and associated random access procedures performed between an A-IoT device reader and one or more A-IoT devices 3-1.

[0128] For example, as described in more detail later, the communication system 1 may beneficially be configured to support one or more enhancements to the A-IoT paging and random access (RA) procedure described with reference to Fig. 5. Moreover, as described in more detail later, the communication system 1 may beneficially be configured to support one or more enhancements for supporting wake-up of A-IoT devices 3-1 in an A-IoT paging and random access (RA) procedure.

[0129] It will be appreciated that one or more of the enhancements described in more detail below may be implemented to provide a commensurate benefit.

[0130] Several enhancements to an A-IoT paging and procedure between an A-IoT device reader and one or more A-IoT devices 3-1 will now be described in further detail with respect to Figs. 6 to 16.

[0131] <Enhanced Initial RA Procedures for A-IoT> <Follow-up round indication in follow-up RA trigger messages / A-IoT paging messages> 　　Fig. 7 illustrates an enhanced A-IoT paging and RA procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices 3-1 that may be implemented in the communication system 1.

[0132] As shown in Fig. 7, there is provided an A-IoT device reader (e.g., a RAN node 5-1, an intermediate / assisting node 5-2, or some other appropriate device) that may wish to communication with one or more A-IoT devices 3-1. To communicate with the one or more A-IoT devices 3-1, the A-IoT device reader triggers an enhanced RA procedure such as that shown in Fig. 7.

[0133] <Paging A: First Round> 　　In the enhanced RA procedure of Fig. 7, at step S702a, having decided / determined that it wants to communicate with one or more A-IoT devices 3-1, the A-IoT device reader sends an (initial) RA trigger message / appropriate A-IoT paging message to the A-IoT device / devices 3-1 as part of a first paging round of a Paging 'A'.

[0134] The RA trigger message / A-IoT paging message, sent at step S702a may, for example, be the same as the RA trigger message / A-IoT paging message sent at step S502a of Fig. 5. It will therefore be appreciated that the description above with respect to the RA trigger message / A-IoT paging message sent at step S502a may apply equally to step S702a. Additionally, at step S702a the RA trigger message / A-IoT paging message sent to the A-IoT device / devices 3-1 may include all necessary paging-relevant information associated with the first paging round of Paging A.

[0135] For example, the RA trigger message / A-IoT paging message sent at step S702a may include (optionally) a paging value-tag / ID that identifies the specific paging (e.g., Paging A) with which the RA trigger message / A-IoT paging message is associated (e.g., Paging A has a paging value-tag / ID of 'A', Paging B has a paging value-tag / ID of 'B', etc). In this way, RA trigger messages / A-IoT paging messages associated with a same paging (e.g., Paging A), but which are sent in different paging rounds have the same paging value-tag / ID.

[0136] It will be appreciated that the inclusion of such a paging value-tag / ID in each RA trigger message / A-IoT paging message beneficially enables target A-IoT devices 3-1 to identify when RA trigger messages / A-IoT paging messages sent to the target A-IoT devices 3-1 are an initial RA trigger message / A-IoT paging message associated with a first paging round of a specific paging (e.g., Paging A), or a follow-up RA trigger message / A-IoT paging message associated with subsequent paging rounds of a same paging (e.g., Paging A).

[0137] Additionally (or alternatively), the RA trigger message / A-IoT paging message, sent at step S702a may include an appropriate indication of the target A-IoT devices 3-1 that the A-IoT device reader wishes to access. For example, the RA trigger message / A-IoT paging message may include an appropriate ID of individual target A-IoT devices 3-1 that the A-IoT device reader wishes to access, an appropriate ID associated with types / groups / subsets of target A-IoT devices 3-1, or the like.

[0138] Additionally (or alternatively), the RA trigger message / A-IoT paging message, sent at step S702a may include appropriate access information for use in the RA procedure. For example, the initial RA trigger message / A-IoT paging message may include information pertaining to the number of random access occasion (RO) slots that are available for the A-IoT devices 3-1 to send corresponding D2R transmissions to the A-IoT device reader.

[0139] While the additional information (e.g., the optional paging-value-tag / ID, the ID / IDs (and / or group IDs) of target A-IoT devices 3-1, and the access information for use in the RA procedure) is described above as being within the RA trigger message / A-IoT paging message sent at step S702a, it will nevertheless be appreciated that such additional information may alternatively be indicated / sent to the target A-IoT devices 3-1 in a separate (dedicated) message (e.g., a dedicated paging message) sent shortly after the RA trigger message / A-IoT paging message sent at step S702a to trigger the RA procedure between the A-IoT device reader and the target A-IoT devices 3-1.

[0140] Having received the initial RA trigger message / A-IoT paging message at step S702a, each target A-IoT device 3-1 may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown).

[0141] At step S704a, following transmission of the RA trigger message / A-IoT paging message sent at S702a, the A-IoT device reader may transmit, to the target A-IoT devices 3-1, a first individual RO slot#0 indication message / signal to indicate a start point of the RO slot#0. Alternatively, rather than transmitting a first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 at step S704a, the first individual RO slot#0 may instead be implicitly indicated in the RA trigger message / A-IoT paging message sent at step S702a.

[0142] At step S706a, following transmission of the first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 (or following implicit indication of the first individual RO slot#0 in the initial RA trigger message / A-IoT paging message), any of the target A-IoT devices 3-1 that have randomly selected RO slot#0 for performing an RA procedure with the A-IoT device reader performs that RA procedure by sending an appropriate D2R transmission to the A-IoT device reader using the RO slot#0.

[0143] After an RA procedure has been attempted, at step S706a, between the A-IoT device reader and one or more of the target A-IoT devices 3-1, the A-IoT device reader and target A-IoT devices 3-1 may engage in one or more further RA cycles (S720). The steps of each further RA (e.g., steps, S708a, and S710a) are similar to steps S508a and S510a of Fig. 5 respectively as described above. The description of those steps above is thus also generally applicable to for steps, S708a and S710a of Fig. 7.

[0144] It will be appreciated that the further RA cycles (at S720) may be repeated as many times as deemed necessary by the A-IoT device reader.

[0145] <Paging A: Second Round> 　　Following the first paging round of a Paging A (steps S702a to S710a), the A-IoT device reader may initiate, where appropriate, a second paging round of Paging A that is a repeat of the first paging round. For example, where some of the target A-IoT devices 3-1 that the A-IoT device reader wishes to communicate with were unable to successfully perform an RA procedure with the A-IoT device reader (e.g., because they were unable to select / use an appropriate RO slot, because they were asleep, or because of some other reason), the A-IoT device reader may attempt to access those target A-IoT devices 3-1 again in a second paging round of Paging A.

[0146] For example, as shown in Fig. 7, at step S702b, the A-IoT device reader sends a follow-up RA trigger message / A-IoT paging message to the target A-IoT devices 3-1. However, that follow-up RA trigger message / A-IoT paging message (unlike in the procedure illustrated in Fig. 5) contains a minimum amount of information.

[0147] For example, if the RA trigger message / A-IoT paging message sent at step S702a included a paging value-tag / ID as described above, then the follow-up RA trigger message / A-IoT paging message sent at step S702b may (optionally) also include the same paging value-tag / ID. In this way the follow-up RA trigger message / A-IoT paging message sent to the target A-IoT devices 3-1 at step S702b in the second paging round of Paging A may be explicitly linked to the message / A-IoT paging message sent to the target A-IoT devices 3-1 at step S702a in the first paging round of Paging A.

[0148] It will be appreciated that the inclusion of such a paging value-tag / ID in the follow-up RA trigger message / A-IoT paging message beneficially enables the target A-IoT devices 3-1 to identify that the follow-up RA trigger message sent to the A-IoT devices 3-1 at step S702b is part of another paging round (e.g., a second paging round) of the same paging triggered by the RA trigger message / A-IoT paging message sent at step S702a (e.g., Paging A).

[0149] Alternatively, the follow-up RA trigger message / A-IoT paging message, unlike the RA trigger message / A-IoT paging message sent at step S702a, may not include a paging value-tag / ID. In this scenario, the absence of such a paging value-tag / ID may implicitly indicate to the target A-IoT devices 3-1 that receive the follow-up RA trigger message / A-IoT paging message that the follow-up RA trigger message / A-IoT paging message is part of another paging round (e.g., a second paging round) of the same paging triggered by the last RA trigger message / A-IoT paging message that included a paging value-tag / ID received by the target A-IoT devices 3-1 (e.g., the RA trigger message / A-IoT paging message received at step S702a).

[0150] Additionally (or alternatively), the follow-up RA trigger message / A-IoT paging message sent at step S702b may (optionally) include a paging round number N, or the like, that indicates to the target A-IoT devices 3-1 that the follow-up RA trigger message / A-IoT paging message is associated with an Nthpaging round of a specific paging (e.g., Paging A). For example, the follow-up RA trigger message / A-IoT paging message sent at step S702b may include a paging round number '1' to indicate that it is associated with a second paging round of a specific paging (e.g., Paging A) - it will be appreciated that in this example, the initial RA trigger message / A-IoT paging message sent at step S702a may include a paging round number '0'.

[0151] Additionally (or alternatively), the follow-up RA trigger message / A-IoT paging message sent at step S702b may include an appropriate indication of configured RA occasions (ROs) that can be randomly selected by the target A-IoT devices 3-1 for D2R transmissions to the A-IoT device reader as part of an RA procedure. For example, the follow-up RA trigger message / A-IoT paging message sent at step S702b may include an appropriate indication of a number ('Y') of ROs that have been configured by the A-IoT device reader for use by the A-IoT device 3-1 in performing D2R transmissions as part of an RA procedure with the A-IoT device reader. The number (Y) may be different to the number (X) of ROs that have been configured by the A-IoT device reader for use by the A-IoT device 3-1 in performing D2R transmissions as part of an RA procedure with the A-IoT device reader indicated in the RA trigger message / A-IoT paging message sent at step S702a.

[0152] It will be appreciated that Y may be different from X because the number (amount) of RO slots indicated to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message sent at step S702a may need to be greater than the number of RO slots indicated to the target A-IoT devices 3-1 in the follow-up RA trigger message / A-IoT paging message sent at step S702b to take account in changes in load on the system between different paging rounds of a same paging (e.g., Paging A). For example, the number of RO slots indicated to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message sent at step S702a may be large as none of target A-IoT devices 3-1 to which the RA trigger message / A-IoT paging message is sent at step S702a have completed a successful RA procedure with the A-IoT device reader. However, assuming that some of the target A-IoT devices 3-1 to which the RA trigger message / A-IoT paging message is sent to at step S702a successfully complete the RA procedure with the A-IoT device reader, when the A-IoT device reader sends the follow-up RA trigger message / A-IoT paging message at step S702b, only those target A-IoT devices 3-1 that previously suffered an RA failure with the A-IoT device reader will need to perform an D2R transmission to the A-IoT device reader as part of an RA procedure. Accordingly, fewer RO slots will be required, and thus the follow-up RA trigger message / A-IoT paging message sent at step S702b may indicate fewer RO slots to the target A-IoT devices 3-1.

[0153] Following transmission of that follow-up RA trigger message / A-IoT paging message at step S702a each target A-IoT device 3-1 may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown), and the procedure at steps S704a to S710a as described above may be repeated within the second paging round for Paging A.

[0154] <Paging B: First Round> 　　Sometime later, at step S712a, having decided / determined that it wants to communicate with different A-IoT device / devices 3-1 from those targeted by the A-IoT device reader in Paging A, the A-IoT device reader sends a new (initial) RA trigger message / new (initial) A-IoT paging message to those different A-IoT device / devices 3-1. For example, at some later time, the A-IoT device reader may decide that it wishes to communicate with a different type / group / subset of A-IoT devices 3-1 that it communicated with earlier via Paging A, and may trigger a new paging (e.g., Paging B), which is directed toward that different type / group / subset of A-IoT devices 3-1.

[0155] It will be appreciated that the new RA trigger message / new A-IoT paging message sent at step S712a may, for example, be the same as the RA trigger message / A-IoT paging message sent at step S512a of Fig. 5. It will therefore be appreciated that the description above with respect to the RA trigger message / A-IoT paging message sent at step S512a may apply equally to step S712a.

[0156] Additionally, at step S712a the new RA trigger message / new A-IoT paging message sent to the A-IoT device / devices 3-1 may include all necessary paging-relevant information associated with the first paging round of Paging B.

[0157] For example, the new RA trigger message / new A-IoT paging message sent at step S712a may include (optionally) a paging value-tag / ID that identifies the specific paging (e.g., Paging B) with which the new initial RA trigger message / new initial A-IoT paging message is associated (e.g., Paging A has a paging value-tag / ID of 'A', Paging B has a paging value-tag / ID of 'B', etc). In this way, new initial RA trigger messages / new initial A-IoT paging message associated with a same paging (e.g., Paging B), but which are sent in different paging rounds may have the same paging value-tag / ID.

[0158] Additionally (or alternatively), the new RA trigger message / new A-IoT paging message, sent at step S712a may include an appropriate indication of the target A-IoT devices 3-1 that the A-IoT device reader wishes to access. For example, the new initial RA trigger message / new initial A-IoT paging message may include an appropriate ID of individual targeted A-IoT devices 3-1 that the A-IoT device reader wishes to access, an appropriate ID associated with types / groups / subsets of target A-IoT devices 3-1, or the like.

[0159] Additionally (or alternatively), the new RA trigger message / new A-IoT paging message, sent at step S712a may include appropriate access information for use in the RA procedure. For example, the new initial RA trigger message / new initial A-IoT paging message may include information pertaining to the number of random access occasion (RO) slots that are available for the A-IoT devices 3-1 to send corresponding D2R transmissions to the A-IoT device reader.

[0160] While the additional information (e.g., the optional paging-value-tag / ID, the ID / IDs (or group ID) of target A-IoT devices 3-1, and the access information for use in the RA procedure) is described above as being within the new initial RA trigger message / new initial A-IoT paging message sent at step S712a, it will nevertheless be appreciated that such additional information may alternatively be indicated / sent to the target A-IoT devices 3-1 in a separate (dedicated) message (e.g., a dedicated paging message) sent shortly after the new initial RA trigger message / new initial A-IoT paging message to trigger the RA procedure between the A-IoT device reader and the target A-IoT devices 3-1.

[0161] Having received the new RA trigger message / new A-IoT paging message at step S702a, each target A-IoT device 3-1 may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown).

[0162] Following the transmission of the new RA trigger message / new A-IoT paging message, sent at step S712a, the procedure at steps S704a to S710a are repeated albeit with respect to Paging B.

[0163] Fig. 8 illustrates an example set of paging round attempts by different A-IoT devices 3-1 in accordance with the enhanced initial RA procedure of Fig. 7.

[0164] As shown in Fig. 8, following transmission of an RA trigger message / A-IoT paging message for a Paging (e.g., Paging A) by an A-IoT device reader, target A-IoT devices 3-1 (e.g., A-IoT device #1, A-IoT device #2, and A-IoT device #3) may each attempt an RA procedure with the A-IoT device reader that sent the RA trigger message / A-IoT paging message if each of those A-IoT devices 3-1 were paged (i.e., targeted) by the A-IoT device 3-1.

[0165] For example, having received the RA trigger message / A-IoT paging message for a Paging (e.g., Paging A), the target A-IoT devices 3-1 may randomly select an RO slot#i for use in performing an D2R transmission to the A-IoT device reader, the randomly selected RO slot#i being randomly selected from a set of X RO slots indicated to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message.

[0166] For each target A-IoT device 3-1, upon receiving an RO slot# indication from the A-IoT device reader indicating the starting position of an RO slot corresponding to the RO slot that they have randomly selected for use in performing an D2R transmission to the A-IoT device reader, the target A-IoT device 3-1 may perform an RA procedure with the A-IoT device reader.

[0167] As shown in Fig. 8 by way of example only, the A-IoT device #1, having initiated an RA procedure with A-IoT device reader, may successfully manage to complete the procedure and access the A-IoT device reader in a first paging round.

[0168] However, if one or more of the target A-IoT devices 3-1 (e.g., A-IoT devices #2 and #3) fail to complete the RA procedure in the first paging round (for example, some of the A-IoT devices 3-1 fail to receive one or more messages from the A-IoT device reader that form part of the RA procedure) then the those A-IoT devices 3-1 may monitor for a follow-up RA trigger message in a subsequent paging round, and may successfully manage to complete an RA procedure and access the A-IoT device reader in a second, third, etc. paging round of the same paging (e.g., Paging A).

[0169] It will be appreciated that the transmission of follow-up RA trigger messages for subsequent paging rounds associated with a specific paging (e.g., Paging A) may continue until all paged A-IoT devices 3-1 have successfully completed an RA procedure with the A-IoT device reader.

[0170] It will also be appreciated that where the follow-up RA trigger messages #1, #2 include an paging round number N, or the like, that indicates to the target A-IoT devices 3-1 that the follow-up RA trigger message / A-IoT paging message is associated with an Nthpaging round of a specific paging (e.g., Paging A), as described above with reference to Fig. 7, target A-IoT devices 3-1 that receive the follow-up RA trigger messages, but which have already successfully completed an RA procedure for the specific paging (e.g., Paging A) in an earlier paging round may ignore those follow-up RA trigger messages, and thus they do not have to respond to the follow-up RA trigger messages.

[0171] <Paging-value-tag indication in RA trigger messages / A-IoT paging messages> 　　Fig. 9 illustrates another enhanced A-IoT paging and RA procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices 3-1 that may be implemented in the communication system 1.

[0172] As shown in Fig. 9, there is provided an A-IoT device reader (e.g., an RAN node 5-1, an intermediate / assisting node 5-2, or some other appropriate device) that may wish to communication with one or more A-IoT devices 3-1. To communicate with the one or more A-IoT devices 3-1, the A-IoT device reader triggers an enhanced RA procedure such as that shown in Fig. 9.

[0173] <Paging A: First Round> 　　In the enhanced RA procedure of Fig. 9, at step S902a, having decided / determined that it wants to communicate with one or more A-IoT devices 3-1, the A-IoT device reader sends an RA trigger message / appropriate A-IoT paging message to the A-IoT device / devices 3-1 as part of first paging round of a Paging 'A'.

[0174] The RA trigger message / A-IoT paging message, sent at step S902a may, for example, be the same as the RA trigger message / A-IoT paging message sent at step S502a of Fig. 5. It will therefore be appreciated that the description above with respect to the RA trigger message / A-IoT paging message sent at step S502a may apply equally to step S902a.

[0175] Additionally, at step S902a the RA trigger message / A-IoT paging message sent to the target A-IoT devices 3-1 may include all necessary paging-relevant information associated with the first paging round of Paging A.

[0176] For example, the RA trigger message / A-IoT paging message sent at step S902a includes a paging value-tag / ID that identifies the specific paging (e.g., Paging A) with which the RA trigger message / A-IoT paging message is associated (e.g., Paging A has a paging value-tag / ID of 'A', Paging B has a paging value-tag / ID of 'B' / 'A'+1, etc). In this way, RA trigger messages / A-IoT paging message associated with a same paging (e.g., Paging A), but which are sent in different paging rounds may have the same paging value-tag / ID.

[0177] It will be appreciated that the inclusion of such a paging value-tag / ID in each RA trigger message / A-IoT paging message beneficially enables the target A-IoT devices 3-1 to identify when RA trigger messages / A-IoT paging messages sent to the target A-IoT devices 3-1 are an initial RA trigger message / A-IoT paging message associated with a first paging round of a specific paging (e.g., Paging A), or a follow-up RA trigger message / A-IoT paging message associated with subsequent paging rounds of a same paging (e.g., Paging A).

[0178] In some scenarios the RA trigger message / A-IoT paging message sent at step S902a may not include a paging value-tag / ID. For example, in the case where the RA trigger message / A-IoT paging message is transmitted to page a single (individually targeted) A-IoT device 3-1, the likelihood of needing multiple paging rounds to facilitate the RA procedure between the single A-IoT device 3-1 and the A-IoT device reader is greatly reduced and thus no paging value-tag / ID may be necessary.

[0179] Additionally (or alternatively), the RA trigger message / A-IoT paging message, sent at step S902a may include an appropriate indication of the target A-IoT devices 3-1 that the A-IoT device reader wishes to access. For example, the RA trigger message / A-IoT paging message may include an appropriate ID of individual A-IoT devices 3-1 that the A-IoT device reader wishes to access, an appropriate ID associated with types / groups / subsets of target A-IoT devices 3-1, or the like.

[0180] Additionally (or alternatively), the RA trigger message / A-IoT paging message, sent at step S902a may include appropriate access information for use in the RA procedure. For example, the initial RA trigger message / A-IoT paging message may include information pertaining to the number of random access occasion (RO) slots that are available for the A-IoT devices 3-1 to send corresponding D2R transmissions to the A-IoT device reader.

[0181] For example, the access information for use in the RA procedure may include an appropriate indication to indicate RA occasion numbers in the time domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message a Q value, wherein the number of RA occasions provided for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader is equal to 2Q. Alternatively, the information pertaining to the RA occasions / RO slots may also include an appropriate indication to indicate RA occasion numbers in the frequency domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message a P value wherein the number of RA occasions provided for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader is equal to 2P.

[0182] Having received the RA trigger message / A-IoT paging message at step S902a, each target A-IoT device 3-1 may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown).

[0183] At step S904a, following transmission of the RA trigger message / A-IoT paging message sent at step S902a, the A-IoT device reader may transmit, to the target A-IoT devices 3-1, a first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0. Alternatively, rather than transmitting a first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 at step S704a, the first individual RO slot#0 may instead be implicitly indicated in the RA trigger message / A-IoT paging message sent at S902a.

[0184] At step S906a, following transmission of the first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 (or following implicit indication of the first individual RO slot#0 in the initial RA trigger message / A-IoT paging message), any of the target A-IoT devices 3-1 that have randomly selected RO slot#0 for performing an RA procedure with the A-IoT device reader performs that RA procedure by sending an appropriate D2R transmission to the A-IoT device reader using the RO slot#0.

[0185] At step S906a, following transmission of the first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 (or following implicit indication of the first individual RO slot#0 in the initial RA trigger message / A-IoT paging message), any of the target A-IoT devices 3-1 that have randomly selected RO slot#0 for performing an RA procedure with the A-IoT device reader performs that RA procedure by sending an appropriate D2R transmission to the A-IoT device reader using the RO slot#0.

[0186] After an RA procedure has been attempted, at step S906a, between the A-IoT device reader and one or more of the target A-IoT devices 3-1, the A-IoT device reader and target A-IoT devices 3-1 may engage in one or more further RA cycles (S920). The steps of each further RA (e.g., steps, S908a, and S910a) are similar to steps S508a and S510a of Fig. 5 respectively as described above. The description of those steps above is thus also generally applicable to for steps, S908a and S910a of Fig. 9.

[0187] It will be appreciated that the further RA cycles (at S920) may be repeated as many times as deemed necessary by the A-IoT device reader.

[0188] <Paging B: First Round> 　　Following the first paging round of paging A (steps S902a to S910a), having decided / determined that it wants to communicate with different A-IoT devices 3-1 from those targeted by the A-IoT device reader in Paging A, the A-IoT device reader may at step S912a send a new RA trigger message / new A-IoT paging message to page those different A-IoT devices 3-1. For example, the A-IoT device reader may decide that it wishes to communicate with a different type / group / subset of A-IoT devices 3-1 that it communicated with earlier via Paging A, and may trigger a new paging (e.g., Paging B), which is directed toward that different type / group / subset of A-IoT devices 3-1.

[0189] It will be appreciated that the new RA trigger message / A-IoT paging message sent at step S912a may, for example, be the same as the RA trigger message / A-IoT paging message sent at step S512b of Fig. 5. It will therefore be appreciated that the description above with respect to the RA trigger message / A-IoT paging message sent at step S512a may apply equally to step S912a.

[0190] Additionally, at step S912a the new RA trigger message / A-IoT paging message sent to the target A-IoT devices 3-1 includes all necessary paging-relevant information associated with the first paging round of Paging B.

[0191] For example, the new RA trigger message / A-IoT paging message sent at step S912a includes a paging value-tag / ID that identifies the specific paging (e.g., Paging B) with which the new RA trigger message / A-IoT paging message is associated (e.g., Paging A has a paging value-tag / ID of 'A', Paging B has a paging value-tag / ID of 'B' / 'A'+1, etc). In this way, new initial RA trigger messages / A-IoT paging message associated with a same paging (e.g., Paging B), but which are sent in different paging rounds may have the same paging value-tag / ID.

[0192] In some scenarios the new RA trigger message / A-IoT paging message sent at step S912a may not include a paging value-tag / ID. For example, in the case where the new RA trigger message / A-IoT paging message is transmitted to page a single A-IoT device 3-1, the likelihood of needing multiple paging rounds to facilitate the RA procedure between the single A-IoT device 3-1 and the A-IoT device reader is greatly reduced and thus no paging value-tag / ID may be necessary.

[0193] Additionally (or alternatively), the new RA trigger message / A-IoT paging message, sent at step S912a may include an appropriate indication of the A-IoT devices 3-1 that the A-IoT device reader wishes to access. For example, the new RA trigger message / A-IoT paging message may include an appropriate ID of individual A-IoT devices 3-1 that the A-IoT device reader wishes to access, an appropriate ID associated with types / groups / subsets of A-IoT devices 3-1, or the like.

[0194] Additionally (or alternatively), the new RA trigger message / A-IoT paging message, sent at step S912a may include appropriate access information for use in the RA procedure. For example, the initial RA trigger message / A-IoT paging message may include information pertaining to the number of random access occasion (RO) slots that are available for the A-IoT devices 3-1 to send corresponding D2R transmissions to the A-IoT device reader.

[0195] For example, the access information for use in the RA procedure may include an appropriate indication to indicate RA occasion numbers in the time domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1, in the new RA trigger message / A-IoT paging message, a Q value, wherein the number of RA occasions provided for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader is equal to 2Q. Alternatively, the information pertaining to the RA occasions / RO slots may also include an appropriate indication to indicate RA occasion numbers in the frequency domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1 in the new RA trigger message / A-IoT paging message a P value wherein the number of RA occasions provided for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader is equal to 2P.

[0196] Following transmission of that follow-up RA trigger message / A-IoT paging message at step S702a each target A-IoT device 3-1 may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown), and the procedure at steps S904a to S910a as described above may be repeated within albeit with respect to a first paging round for Paging B.

[0197] <Paging A: Second Round> 　　At some time later, a second paging round of Paging A may be triggered by the A-IoT device reader to attempt to perform an RA procedure with those target A-IoT devices 3-1 targeted in Paging A which did not previously successfully complete the RA procedure. For example, at step S902b as shown in Fig. 9, the A-IoT device reader sends a follow-up RA trigger message / A-IoT paging message to the target A-IoT devices 3-1 for Paging A.

[0198] The RA trigger message / A-IoT paging message, sent at step S902b may, for example, be the same as the RA trigger message / A-IoT paging message sent at step S502b of Fig. 5. It will therefore be appreciated that the description above with respect to the RA trigger message / A-IoT paging message sent at step S502b may apply equally to step S902b.

[0199] Additionally, at step S902b the RA trigger message / A-IoT paging message sent to the target A-IoT devices 3-1 may include all necessary paging-relevant information associated with the first paging round of Paging A.

[0200] For example, the RA trigger message / A-IoT paging message sent at step S902b includes a paging value-tag / ID that identifies the specific paging (e.g., Paging A) with which the RA trigger message / A-IoT paging message is associated (e.g., Paging A has a paging value-tag / ID of 'A', Paging B has a paging value-tag / ID of 'X' / 'A'+1, etc). In this way, RA trigger messages / A-IoT paging message associated with a same paging (e.g., Paging A), but which are sent in different paging rounds may have the same paging value-tag / ID.

[0201] It will be appreciated that the inclusion of such a paging value-tag / ID in each RA trigger message / A-IoT paging message beneficially enables the target A-IoT devices 3-1 to identify when RA trigger messages / A-IoT paging messages sent to the target A-IoT devices 3-1 are an initial RA trigger message / A-IoT paging message associated with a first paging round of a specific paging (e.g., Paging A), or a follow-up RA trigger message / A-IoT paging message associated with subsequent paging rounds of a same paging (e.g., Paging A).

[0202] In some scenarios the RA trigger message / A-IoT paging message sent at step S902b may not include a paging value-tag / ID. For example, in the case where the RA trigger message / A-IoT paging message is transmitted to page a single (individually targeted) A-IoT device 3-1, the likelihood of needing multiple paging rounds to facilitate the RA procedure between the single A-IoT device 3-1 and the A-IoT device reader is greatly reduced and thus no paging value-tag / ID may be necessary.

[0203] Additionally (or alternatively), the RA trigger message / A-IoT paging message, sent at step S902b may include an appropriate indication of the target A-IoT devices 3-1 that the A-IoT device reader wishes to access. For example, the RA trigger message / A-IoT paging message may include an appropriate ID of individual A-IoT devices 3-1 that the A-IoT device reader wishes to access, an appropriate ID associated with types / groups / subsets of target A-IoT devices 3-1, or the like.

[0204] Additionally (or alternatively), the RA trigger message / A-IoT paging message, sent at step S902b may include appropriate access information for use in the RA procedure. For example, the initial RA trigger message / A-IoT paging message may include information pertaining to the number of random access occasion (RO) slots that are available for the A-IoT devices 3-1 to send corresponding D2R transmissions to the A-IoT device reader.

[0205] For example, the access information for use in the RA procedure may include an appropriate indication to indicate RA occasion numbers in the time domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message a Q value, wherein the number of RA occasions provided for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader is equal to 2Q. Alternatively, the information pertaining to the RA occasions / RO slots may also include an appropriate indication to indicate RA occasion numbers in the frequency domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message a P value wherein the number of RA occasions provided for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader is equal to 2P.

[0206] Having received the RA trigger message / A-IoT paging message at step S902b, each target A-IoT device 3-1 that was paged by the RA trigger message / A-IoT paging message at step S902a, but which did not manage to successfully complete a RA procedure following receipt of the RA trigger message / A-IoT paging message at step S902a may randomly select one of the configured ROs for performing an RA procedure with the A-IoT device reader (not shown) and, the procedure at steps S904a to S910a as described above may be repeated with respect to a second paging round for Paging A.

[0207] Fig. 10 illustrates an example set of paging round attempts by different A-IoT devices in accordance with the example A-IoT paging and random access (RA) of Fig. 9.

[0208] As shown in Fig. 10, following transmission of an RA trigger message / A-IoT paging message for a Paging (e.g., Paging A) by an A-IoT device reader, target A-IoT devices 3-1 (e.g., A-IoT device #1, A-IoT device #2, A-IoT device #3, and A-IoT device #4) may each attempt an RA procedure with the A-IoT device reader that sent the RA trigger message / A-IoT paging message if each of those A-IoT devices were paged (i.e., targeted) by the A-IoT device 3-1.

[0209] For example, having received the RA trigger message / A-IoT paging message for a Paging (e.g., Paging A) with a first paging value-tag / ID, the target A-IoT devices 3-1 may randomly select an RO slot#i for use in performing a D2R transmission to the A-IoT device reader, the randomly selected RO slot#i being randomly selected from a set of RO slots indicated to the target A-IoT devices 3-1 in the RA trigger message / A-IoT paging message.

[0210] For each target A-IoT device 3-1, upon receiving an RO slot# indication from the A-IoT device reader indicating the starting position of an RO slot corresponding to the RO slot that they have randomly selected for use in performing an UL transmission to the A-IoT device reader, the target A-IoT device 3-1 may perform an RA procedure with the A-IoT device reader.

[0211] As shown in Fig. 10 by way of example only, the A-IoT device #1, having initiated an RA procedure with A-IoT device reader, may successfully manage to complete the procedure and access the A-IoT device reader in a first paging round. Having successfully completed the RA procedure, the A-IoT device #1 may, for example, store within its memory a copy of the paging value-tag / ID contained in the RA trigger message / A-IoT paging message for a Paging (e.g., Paging A) it received. Storage of that value-tag / ID in the memory of the A-IoT device #1 may, for example, act as a flag or mark that the A-IoT device #1 has successfully responded to an RA trigger message / A-IoT paging message containing that value-tag / ID.

[0212] However, if one or more of the target A-IoT devices 3-1 (e.g., A-IoT device #2) fails to complete the RA procedure in the first paging round (for example, some of the A-IoT devices 3-1 fail to receive one or more messages from the A-IoT device reader that form part of the RA procedure) then the those A-IoT devices 3-1 (e.g., A-IoT device #2), do not store within their memory a copy of the paging value-tag / ID contained in the RA trigger message / A-IoT paging message for a Paging (e.g., Paging A) they received. It will be appreciated that the absence of a paging value-tag / ID corresponding to a specific RA trigger message / A-IoT paging message stored in the memory of one or more of the A-IoT devices 3-1 may act as a flag or mark that those A-IoT devices 3-1 (e.g., A-IoT device #2) has not yet successfully responded to the specific RA trigger message / A-IoT paging message.

[0213] Any A-IoT device 3-1 fails to complete the RA procedure in the first paging round, they may subsequently monitor for a follow-up RA trigger message / A-IoT paging message in a subsequent paging round and may successfully manage to complete an RA procedure and access the A-IoT device reader in a second, third, etc. paging round of the same paging (e.g., Paging A).

[0214] For example, as shown in Fig. 10, A-IoT device #2 monitors for a follow-up RA trigger message / A-IoT paging message in a subsequent paging round (e.g., Paging round #1). Upon receiving the RA trigger message / A-IoT paging message for a Paging (e.g., Paging A) with a first paging value-tag / ID, the A-IoT device #2 determines whether the first paging value-tag / ID corresponds to any paging value-tag / IDs stored in its memory.

[0215] Having determined that there is no corresponding paging value-tag / IDs stored in its memory (because it failed to successfully perform the RA procedure with the initial RA trigger message / A-IoT paging message that contained that paging value-tag / ID, or it has never initiated an RA procedure in response to the initial RA trigger message / A-IoT paging message that contained that paging value-tag / ID), the A-IoT device #2 determines that it has either never responded before (or has previous failed to respond) to an RA trigger message / A-IoT paging message with that paging value-tag / ID, and initiates a RA procedure with the A-IoT device reader.

[0216] On the other hand, as shown in Fig. 10, A-IoT device #1, upon receiving the follow-up RA trigger message / A-IoT paging message in a subsequent paging round (e.g., Paging round #1) determines whether the first paging value-tag / ID corresponds to any paging value-tag / IDs stored in its memory. Having determined that there is a corresponding paging value-tag / IDs stored in its memory (because it successfully performed the RA procedure with the initial RA trigger message / A-IoT paging message that contained that paging value-tag / ID), the A-IoT device #1 may decide not to respond to the follow-up RA trigger message / A-IoT paging message.

[0217] It will be appreciated that the A-IoT devices 3-1 may delete the paging value-tag / IDs stored in their memory once they become obsolete; for example after a (pre)configured number of hours have passed since they were stored, or after receiving an appropriate indication from the A-IoT device reader indicating that the paging value-tag / IDs stored in their memory should be deleted.

[0218] It will also be appreciated that the A-IoT devices 3-1 may be able to store multiple paging value-tag / IDs in their memory at any given time. Alternatively, the A-IoT devices 3-1 may only be able to store one paging value-tag / ID in their memory at a time. In this case, each paging value-tag / ID is overwritten in the memory of the A-IoT devices 3-1 once those devices successfully respond to a new RA trigger message / A-IoT paging message with a different paging value-tag / ID.

[0219] <Target device indication in RA trigger messages / A-IoT paging messages> 　　In the procedure described above with reference to Figs. 9 and 10, the RA trigger messages / A-IoT paging messages include a paging value-tag / ID that assists in identifying which paging (e.g., Paging A vs. Paging B) each RA trigger message / A-IoT paging message sent by the A-IoT device reader to target A-IoT devices 3-1 is associated. In this way, target A-IoT devices 3-1 are able to determine whether an RA trigger message / A-IoT paging message that they receive is a repeat of an earlier RA trigger message / A-IoT paging message that they have already received in a previous paging round of a specific paging (e.g., Paging A), or whether the RA trigger message / A-IoT paging message is an RA trigger message / A-IoT paging message associated with a new paging (e.g., Paging B) to which the target A-IoT devices 3-1 have not yet responded.

[0220] Beneficially, by enabling the target A-IoT devices 3-1 to identify whether an RA trigger message / A-IoT paging message is a repeat of an earlier RA trigger message / A-IoT paging message that they have already received in a previous paging round of a specific paging (e.g., Paging A) and to which they have successfully responded, or whether the RA trigger message / A-IoT paging message is associated with a new paging (e.g., Paging B) to which the target A-IoT devices 3-1 have not yet responded, the target A-IoT devices 3-1 can avoid unnecessarily responding to RA trigger messages / A-IoT paging messages in subsequent paging rounds of a paging (e.g., Paging A) to which they have already responded, thereby reducing signalling overhead in the communication system.

[0221] Nevertheless, it will be appreciated that the inclusion of such a paging value-tag / ID in the RA trigger messages / A-IoT paging messages is only one means of enabling the target A-IoT devices 3-1 from determining whether an RA trigger message / A-IoT paging message it receives is associated with a new paging or another paging round of a paging to which the target A-IoT devices 3-1 have already responded.

[0222] For example, rather than including the paging value-tag / ID in the RA trigger messages / A-IoT paging messages described above with reference to Fig. 9, the A-IoT device reader may instead include an ID (or IDs) associated with the target A-IoT devices 3-1 themselves. Optionally, the A-IoT device reader may also include other information in the RA trigger messages / A-IoT paging messages such as paging causes, an ID of the A-IoT device reader, and the like.

[0223] Additionally (or alternatively), the RA trigger messages / A-IoT paging messages may include appropriate access information for use in the RA procedure. For example, the initial RA trigger message / A-IoT paging message may include information pertaining to the number of random access occasion (RO) slots that are available for the target A-IoT devices 3-1 to send corresponding D2R transmissions to the A-IoT device reader.

[0224] For example, the access information for use in the RA procedure may include an appropriate indication to indicate RA occasion numbers in the time domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1, in the new RA trigger message / A-IoT paging message, a Q value, wherein the number of RA occasions provided for performing an RA procedure between the target A-IoT devices 3-1 and the A-IoT device reader is equal to 2Q. Alternatively, the information pertaining to the RA occasions / RO slots may also include an appropriate indication to indicate RA occasion numbers in the frequency domain. For example, the A-IoT device reader may configure, and indicate to the target A-IoT devices 3-1 in the new RA trigger message / A-IoT paging message a P value wherein the number of RA occasions provided for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader is equal to 2P.

[0225] Fig. 11 illustrates an example of how different RA trigger messages / A-IoT paging messages may overlap with one another in terms of the A-IoT device IDs indicated therein.

[0226] For example, as shown in Fig. 11, where two or more RA trigger messages / A-IoT paging messages include completely different A-IoT device IDs (e.g., the two or more RA trigger messages / A-IoT paging messages are targeting completely different types of A-IoT devices; for example Type A vs. Type B), those two or more RA trigger messages / A-IoT paging messages may be considered to have zero overlap as in Case 1 of Fig. 11.

[0227] In another example, as shown in Fig. 11, where two or more RA trigger messages / A-IoT paging messages include some A-IoT devices IDs that are common between the two or more RA trigger messages / A-IoT paging messages, those two or more RA trigger messages / A-IoT paging messages may be considered to partially overlap as in Case 2 of Fig. 11.

[0228] In yet another example, as shown in Fig. 11, where two or more RA trigger messages / A-IoT paging messages include A-IoT devices IDs that identical between the two or more RA trigger messages / A-IoT paging messages, those two or more RA trigger messages / A-IoT paging messages may be considered to fully overlap as in Case 3 of Fig. 11.

[0229] There now follow a brief explanation of how Case 1, Case 2, and Case 3 of Fig. 11 may be applied with respect to the procedure of Fig. 9.

[0230] For example, upon receiving an RA trigger message / A-IoT paging message (e.g., at steps S902a, S912a, and / or S902b) the target A-IoT devices 3-1 may use the ID (or IDs) included in the RA trigger message / A-IoT paging message to determine whether it is an RA trigger message / A-IoT paging message associated with a new paging, or an RA trigger message / A-IoT paging message associated with another paging round of a paging to which the target A-IoT devices 3-1 have already responded.

[0231] For example, after responding to an RA trigger message / A-IoT paging message associated with a new paging, the target A-IoT devices 3-1 may store in their memory appropriate information associated with the RA trigger message / A-IoT paging message to which they responded (e.g., the ID / IDs of the A-IoT devices indicated in the RA trigger message / A-IoT paging message, the paging cause indicated in the RA trigger message / A-IoT paging message, the ID of the A-IoT device reader RA trigger message / A-IoT paging message, and the like).

[0232] Subsequently, when the target A-IoT devices 3-1 receives another RA trigger message / A-IoT paging message, the target A-IoT devices 3-1 may check (compare) the contents of the RA trigger message / A-IoT paging message with the information it has stored in its memory regarding previously received and responded to RA trigger messages / A-IoT paging messages.

[0233] If, for example, based on information stored in memory regarding previously received and responded to RA trigger messages / A-IoT paging messages, the target A-IoT devices 3-1 determine that the ID (or IDs) of the target A-IoT devices 3-1 in a received RA trigger message / A-IoT paging message received fully overlap with ID (or IDs) of target A-IoT devices 3-1 included in an earlier RA trigger message / A-IoT paging message received, and responded to by the target A-IoT devices 3-1 (Case 3 of Fig. 11), the target A-IoT devices 3-1 may determine that the RA trigger message / A-IoT paging message is associated with another paging round of a paging to which the target A-IoT devices 3-1 have already responded. In this case, the target A-IoT devices 3-1 may ignore the RA trigger message / A-IoT paging message.

[0234] Alternatively, if, based on information stored in memory regarding previously received and responded to RA trigger messages / A-IoT paging messages, the target A-IoT devices 3-1 determine that the ID (or IDs) of the target A-IoT devices 3-1 in a received RA trigger message / A-IoT paging message received partially overlap with ID (or IDs) of target A-IoT devices 3-1 included in an earlier RA trigger message / A-IoT paging message received, and responded to by the target A-IoT devices 3-1 (Case 2 of Fig. 11), the target A-IoT devices 3-1 may determine that the RA trigger message / A-IoT paging message is associated with a new paging to which the A-IoT devices 3-1 should respond. In this case, the target A-IoT devices 3-1 may initiate an RA procedure to respond to the RA trigger message / A-IoT paging message as described above with respect to step S906a of Fig. 9.

[0235] Alternatively, if, based on information stored in memory regarding previously received and responded to RA trigger messages / A-IoT paging messages, the target A-IoT devices 3-1 determine that the ID (or IDs) of the target A-IoT devices 3-1 in a received RA trigger message / A-IoT paging message received do not overlap with ID (or IDs) of target A-IoT devices 3-1 included in an earlier RA trigger message / A-IoT paging message received, and responded to by the target A-IoT devices 3-1 (Case 1 of Fig. 11), the target A-IoT devices 3-1 may determine that the RA trigger message / A-IoT paging message is associated with a new paging to which the A-IoT devices 3-1 should respond. In this case, the target A-IoT devices 3-1 may initiate an RA procedure to respond to the RA trigger message / A-IoT paging message as described above with respect to step S906a of Fig. 9.

[0236] It will be appreciated that the appropriate information stored in memory regarding previously received and responded to RA trigger messages / A-IoT paging messages by the target A-IoT devices 3-1 may be deleted once the stored information becomes obsolete (e.g., after a (pre)configured number of hours have elapsed since they were initially stored in memory, and / or in response to an appropriate command message from the A-IoT device reader).

[0237] <Triggering target A-IoT devices to stop responding to RA trigger messages / A-IoT paging messages> 　　In the procedure described above with reference to Figs. 7 to 11, target A-IoT devices 3-1 determine whether or not to respond to an RA trigger message / A-IoT paging message based on determining, one way or another, whether an RA trigger message / A-IoT paging message is a repeat of an earlier RA trigger message / A-IoT paging message that they have already received in a previous paging round of a specific paging (e.g., Paging A) and to which they have successfully responded, or whether the RA trigger message / A-IoT paging message is associated with a new paging (e.g., Paging B) to which the target A-IoT devices 3-1 have not yet responded.

[0238] Alternatively however, the target A-IoT devices 3-1 may be (pre)configured to switch to a 'no-paging monitoring / no RA procedure' status in which they stop monitoring for RA trigger messages / A-IoT paging messages based on one or more conditions. For example, the target A-IoT devices 3-1 may be (pre)configured to switch to a 'no-paging monitoring / no RA procedure' status in once they start a paging response to a received RA trigger message / A-IoT paging message via an RA procedure. Alternatively, the target A-IoT devices 3-1 may be (pre)configured to switch to a 'no-paging monitoring / no RA procedure' status in once they start a paging response to a received RA trigger message / A-IoT paging message via an RA procedure, and once they have successfully completed that RA procedure.

[0239] In another example, the target A-IoT devices 3-1 may switch to a 'no-paging monitoring / no RA procedure' status once commanded to do so by the A-IoT device reader via an appropriate command message, or the like.

[0240] Subsequently, the target A-IoT devices 3-1 may switch (back) to a 'paging monitoring / RA procedure' status in which they begin monitoring for RA trigger messages / A-IoT paging messages based on one or more conditions. For example, the target A-IoT devices 3-1 may be (pre)configured to switch to a 'paging monitoring / RA procedure' status upon expiry of an appropriate timer. That timer may, for example, be triggered (e.g., started / restarted), upon entering a 'no-paging monitoring / no RA procedure' status, upon receiving any type of R2D transmission from the A-IoT device reader, upon receiving any form of transmission scheduling from the A-IoT device reader, upon transmission of a D2R transmission to the A-IoT device reader, and / or the like.

[0241] In another example, the target A-IoT devices 3-1 may switch (back) to a 'paging monitoring / RA procedure' status once commanded to do so by the A-IoT device reader via an appropriate command message, or the like.

[0242] In another example, the target A-IoT devices 3-1 may switch (back) to a 'paging monitoring / RA procedure' status upon detecting a paging message or the like from a different A-IoT device reader and / or upon switching / moving to the coverage area of a different A-IoT device reader.

[0243] <Single RA trigger message / A-IoT paging message configured for multiple paging rounds of a Paging> 　　Fig. 12 illustrates another enhanced A-IoT paging and RA procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices 3-1 that may be implemented in the communication system 1.

[0244] As shown in Fig. 12, there is provided an A-IoT device reader (e.g., a RAN node 5-1, an intermediate / assisting node 5-2, or some other appropriate device) that may wish to communication with one or more A-IoT devices 3-1. To communicate with the one or more A-IoT devices 3-1, the A-IoT device reader triggers an enhanced RA procedure such as that shown in Fig. 12.

[0245] <Paging A: First Round> 　　In the enhanced RA procedure of Fig. 12, at step S1202, having decided / determined that it wants to communicate with one or more A-IoT devices 3-1, the A-IoT device reader sends an (initial) RA trigger message / appropriate A-IoT paging message to target A-IoT devices 3-1 as part of first paging round of a Paging 'A'.

[0246] The RA trigger message / A-IoT paging message, sent at step S1202 may, for example, be the same as the initial RA trigger message / A-IoT paging message sent at step S502a of Fig. 5. It will therefore be appreciated that the description above with respect to the initial RA trigger message / A-IoT paging message sent at step S502a may apply equally to step S1202.

[0247] Additionally, at step S1202 the initial RA trigger message / A-IoT paging message sent to the target / devices 3-1 may include an appropriate indication of a number of RO slots that may be used for each paging round of a paging associated with the RA trigger message / A-IoT paging message sent at step S1202. For example, the RA trigger message / A-IoT paging message sent at step S1202 may include a number ('X') of RO slots for a first paging round of a paging (e.g., Paging A), a number ('Y') of RO slots for a second paging round of the same paging (e.g., Paging A), a number ('Z') of RO slots for a third paging round of the same paging (e.g., Paging A) etc.

[0248] Having received the RA trigger message / A-IoT paging message at step S1202, each target A-IoT device 3-1 may initially randomly select one of the configured first X number ROs for performing an RA procedure with the A-IoT device reader (not shown) , e.g., an A-IoT device 3-1 may randomly select a number n between 0 to X-1, then it selects the nth RO, 0<=n<=X.

[0249] At steps S1204, following transmission of the RA trigger message / A-IoT paging message at step S1202, the A-IoT device reader may transmit, to the target A-IoT devices 3-1, a first individual RO slot#0 indication message / signal to indicate a start point of the RO slot#0. Alternatively, rather than transmitting a first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 at step S1204, the first individual RO slot#0 may instead be implicitly indicated in the RA trigger message / A-IoT paging message sent at step S1202.

[0250] At step S1206, following transmission of the first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 (or following implicit indication of the first individual RO slot#0 in the initial RA trigger message / A-IoT paging message), any of the target A-IoT devices 3-1 that have randomly selected RO slot#0 for performing an RA procedure with the A-IoT device reader performs that RA procedure by sending an appropriate D2R transmission to the A-IoT device reader using the RO slot#0.

[0251] After an RA procedure has been attempted, at step S1206, between the A-IoT device reader and one or more of the target A-IoT devices 3-1, the A-IoT device reader and target A-IoT devices 3-1 may engage in one or more further X RA cycles (S1220). Each further RA cycle involves: the A-IoT device reader providing (at step S1208) further RO slot indications (e.g., an RO slot#i indication up to i-1, where i-1 = X = a number of RO slots for a first paging round of a paging (e.g., Paging A)); and one or more target A-IoT devices 3-1 performing the random access procedure with the A-IoT device reader using those indicated RO slots (at step S1210).

[0252] For example, if any of the target A-IoT devices 3-1 were unable to successfully complete an RA procedure using an earlier indicated X slot / slots then they may attempt access in one of the further Y RA cycles. Each further RA cycle involves: the A-IoT device reader providing (at step S1212) further RO slot indications (e.g., an RO slot#i indication up to i-1, where i-1 = X+Y = a number of RO slots for a first paging round of a paging (e.g., Paging A) plus a number of RO slots for a second paging round of a paging (e.g., Paging A)); and one or more target A-IoT devices 3-1 performing the random access procedure with the A-IoT device reader using those indicated RO slots (at step S1210).

[0253] It will be appreciated (although not shown) that if any of the target A-IoT devices 3-1 are unable to successfully complete an RA procedure using both the indicated X slot / slots, and the indicated Y slot / slots, then they may attempt the RA procedure in one of a further Z RA cycles, etc.. It will be appreciated that the further RA cycle may be repeated as many times as deemed necessary by the A-IoT device reader.

[0254] <Paging A: Second Round> 　　Following X RA cycle of a Paging A (steps S1202 to S1210), the A-IoT device reader may continue, where appropriate, a further Y RA cycle of Paging A. For example, where some of the target A-IoT devices 3-1 that the A-IoT device reader wishes to communicate with were unable to successfully perform an RA procedure with the A-IoT device reader (e.g., because they were unable to select / use an appropriate RO slot, because they were asleep, or because of some other reason) during first X RA cycles, the A-IoT device reader may attempt to access those A-IoT devices 3-1 again in these Y RA cycles.

[0255] For example, the A-IoT device reader and target A-IoT devices 3-1 may engage in one or more further RA cycles (S1222). Each further RA cycle (at step S1222) involves: the A-IoT device reader providing (at step S1212) further RO slot indications (e.g., an RO slot#X indication up to X+Y-1, where X = a number of RO slots for a first paging round of a paging (e.g., Paging A), Y = a number of RO slots for a second paging round of the same paging (e.g., Paging A)); and one or more target A-IoT devices 3-1 performing the random access procedure with the A-IoT device reader using those indicated RO slots (at step S1214).

[0256] It will be appreciated that the further paging rounds comprising further RA cycles may be performed by the A-IoT devices 3-1 and the A-IoT device reader as many times as deemed necessary by the A-IoT device reader.

[0257] <Paging B: First Round> 　　Sometime later, at step S1216, having decided / determined that it wants to communicate with different A-IoT device / devices 3-1 from those targeted by the A-IoT device reader in Paging A, the A-IoT device reader sends a new initial RA trigger message / new A-IoT paging message to those different (new target) A-IoT device / devices 3-1 to initiate a first paging round of a Paging 'B'. For example, at some later time, the A-IoT device reader may decide that it wishes to communicate with a different type / group / subset of A-IoT devices 3-1 than it communicated with earlier via Paging A, and may trigger a new paging (e.g., Paging B), which is directed toward that different type / group / subset of A-IoT devices 3-1.

[0258] Following transmission of that new initial RA trigger message / new initial A-IoT paging message at step S1216, the procedure at steps S1204 to S1214 as described above are carried out, albeit with respect to Paging B.

[0259] <Single RA trigger message / A-IoT paging message configured for a shared pool of Ros> 　　Fig. 13 illustrates another enhanced A-IoT paging and RA procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices 3-1 that may be implemented in the communication system 1.

[0260] As shown in Fig. 13, there is provided an A-IoT device reader (e.g., a RAN node 5-1, an intermediate / assisting node 5-2, or some other appropriate device) that may wish to communication with one or more A-IoT devices 3-1. To communicate with the one or more A-IoT devices 3-1, the A-IoT device reader triggers an enhanced RA procedure such as that shown in Fig. 13.

[0261] <Paging A> 　　In the enhanced RA procedure of Fig. 13, there is no clear paging rounds. At step S1302, having decided / determined that it wants to communicate with one or more A-IoT devices 3-1, the A-IoT device reader sends an (initial) RA trigger message / appropriate A-IoT paging message to the A-IoT device / devices 3-1 as part of a Paging 'A'.

[0262] The RA trigger message / A-IoT paging message, sent at step S1302 may, for example, be the same as the initial RA trigger message / A-IoT paging message sent at step S502a of Fig. 5. It will therefore be appreciated that the description above with respect to the initial RA trigger message / A-IoT paging message sent at step S502a may apply equally to step S1302.

[0263] Additionally, at step S1302a the initial RA trigger message / A-IoT paging message sent to the target A-IoT devices 3-1 may include an appropriate indication of a number of RO slots that may be used for a paging associated with the RA trigger message / A-IoT paging message sent at step S1302. For example, the RA trigger message / A-IoT paging message sent at step S1302 may include a first parameter X which can be used by target A-IoT devices 3-1 to randomly select the initial slots for attempting RA for the first time in response to a paging (e.g., Paging A), and a second parameter Y which can be used by target A-IoT devices 3-1 that fail to successfully complete an RA procedure with the A-IoT device reader using the set of RO slots from RO slot#0 to RO slot#X-1 to randomly select a next RO slot for attempting RA for the second time.

[0264] Having received the RA trigger message / A-IoT paging message at step S1302, each target A-IoT device 3-1 may randomly select one of the configured ROs between RO slot#0 to RO slot#X-1 for performing an RA procedure with the A-IoT device reader (not shown).

[0265] At steps S1304, following transmission of the RA trigger message / A-IoT paging message at step S1302, the A-IoT device reader may transmit, to the target A-IoT devices 3-1, a first individual RO slot#0 indication message / signal to indicate a start point of the RO slot#0. Alternatively, rather than transmitting a first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 at step S1304, the first individual RO slot#0 may instead be implicitly indicated in the RA trigger message / A-IoT paging message sent at step S1302.

[0266] At step S1306, following transmission of the first individual RO slot#0 indication message / signal to the target A-IoT devices 3-1 to indicate a start point of the RO slot#0 (or following implicit indication of the first individual RO slot#0 in the initial RA trigger message / A-IoT paging message), any of the target A-IoT devices 3-1 that have randomly selected RO slot#0 for performing an RA procedure with the A-IoT device reader performs that RA procedure at step S1306 by sending an appropriate D2R transmission to the A-IoT device reader using the RO slot#0.

[0267] At step S1308 the A-IoT device reader may transmit, to the target A-IoT devices 3-1, a second individual RO slot#1 indication message / signal to indicate a start point of the RO slot#1, and at step S1310 any of the target A-IoT devices 3-1 that have randomly selected RO slot#1 for performing an RA procedure with the A-IoT device reader performs that RA procedure at by sending an appropriate UL transmission to the A-IoT device reader using the RO slot#1. Steps of S1308 and S1310 may then be repeated on a loop for X-1 number of RO slots.

[0268] By way of example only, in Fig. 13 one of the target A-IoT devices 3-1 (A-IoT device A) is said to randomly select the second RO slot (i.e., RO slot#2) from the X RO slots indicated as being scheduled by the A-IoT device reader for use by A-IoT devices 3-1 in RA procedures with the A-IoT device reader.

[0269] In the example procedure shown in Fig. 13, having randomly selected RO slot#2 from the X RO slots, A-IoT device A may wait for the second RO slot it selected (e.g., A-IoT device A may wait until it receives an individual RO slot indication message / signal at step S1312 for RO slot#2) before attempting an RA procedure with the A-IoT device reader. Upon receiving, from the A-IoT device reader, an individual RO slot indication message / signal for RO slot#2 to indicate a start point of the RO slot#2, the A-IoT device A may attempt an RA procedure (at step S1314) with the A-IoT device reader using that RO slot#2.

[0270] As shown in Fig. 13 however, in the event that A-IoT device A fails to successfully complete an RA procedure with the A-IoT device reader in RO slot#2, the A-IoT device A may, based on the RA trigger message / A-IoT paging message it received at step S1302, randomly select a further RO slot indicated as being scheduled by the A-IoT device reader for use by A-IoT devices 3-1 in RA procedures with the A-IoT device reader.

[0271] That further set of RO slot may be selected by the A-IoT device A such that they are selected from a set of Y RO slots immediately following the RO slot where a target A-IoT devices 3-1 that fail to successfully complete an RA procedure with the A-IoT device reader, i.e., between RO slot#i+1 and RO slot#i+Y, where: -　　RO#i is the first RO slot located after the RO slot where the A-IoT device A failed to perform an RA procedure with the A-IoT device reader. For example, in Fig. 13, the A-IoT device A initially selects RO slot#2 but fails to perform a successful RA procedure using that slot. RO slot#i therefore, in this example, is RO slot#3 as it follows immediately after RO slot#2.

[0272] Having selected a further RO slot, the A-IoT device A may then wait to receive from the A-IoT device reader an individual RO slot indication message / signal for the corresponding RO slot, e.g., mthone of the RO slots (at step S1316), and upon receiving that individual RO slot indication message / signal the A-IoT device A may attempt an RA procedure (at step S1318) with the A-IoT device using that mthRO slot.

[0273] In the event that the RA procedure between A-IoT device A and the A-IoT device reader fails again, then the procedure outlined above may be repeated on loop until the A-IoT device A successfully completes an RA procedure with the A-IoT device reader.

[0274] <Paging B> 　　Sometime later, at step S1320, having decided / determined that it wants to communicate with different A-IoT device / devices 3-1 from those targeted by the A-IoT device reader in Paging A, the A-IoT device reader sends a new initial RA trigger message / new A-IoT paging message to those different (new target) A-IoT device / devices 3-1 to initiate a Paging 'B'. For example, at some later time, the A-IoT device reader may decide that it wishes to communicate with a different type / group / subset of A-IoT devices 3-1 than it communicated with earlier via Paging A, and may trigger a new paging (e.g., Paging B), which is directed toward that different type / group / subset of A-IoT devices 3-1.

[0275] Following transmission of that new initial RA trigger message / new initial A-IoT paging message at step S1320, the procedure at steps S1304 to S1318 as described above are carried out, albeit with respect to Paging B.

[0276] <Configuring and Reconfiguring RO Pool> 　　Fig. 14 illustrates another enhanced A-IoT paging and RA procedure that may be performed between an A-IoT device reader and a plurality of A-IoT devices 3-1 that may be implemented in the communication system 1.

[0277] It will be appreciated that the enhanced initial RA procedure in Fig. 14 is similar to the enhanced initial RA procedure of Fig. 13 except for: -　　The information being provided in the initial RA trigger message / appropriate A-IoT paging message to the A-IoT device / devices 3-1 as part of first paging round of a Paging 'A' sent at step S1402 is different; and -　　The introduction of a new RO reconfiguration message sent by the A-IoT device reader to the A-IoT device 3-1 at step S1415.

[0278] The (initial) RA trigger message / A-IoT paging message sent at step S1402 of Fig. 14 is thus similar to the (initial) RA trigger message / A-IoT paging message sent at step S1302 of Fig. 13. The description above of step S1302 is, therefore, generally applicable to the step S1402. However, the (initial) RA trigger message / A-IoT paging message sent at step S1402 of Fig. 14 includes a Q value 'Q1' configured by the A-IoT device reader. That Q value may be used by the A-IoT devices 3-1 to determine a first number of ROs that are available and scheduled by the A-IoT device reader for performing an D2R transmission as part of a RA procedure between the A-IoT devices 3-1 and the A-IoT device reader.

[0279] For example, the A-IoT devices 3-1 may determine that following the initial RA trigger message / A-IoT paging message sent at step S1402 there are 2QROs scheduled by the A-IoT device reader for use in D2R transmissions as part of a RA procedure. The A-IoT devices 3-1 may then each randomly select one or more of those 2QROs for performing a RA procedure between each respective A-IoT device 3-1 and the A-IoT device reader.

[0280] The steps S1404 to S1414 of Fig. 14 are similar to the steps S1302 to S1314 of Fig. 13. The description above of steps S1302 to S1314 therefore is generally applicable to the steps S1402 to S1414 respectively.

[0281] During the steps S1404 to S1414 of Fig. 14, the A-IoT device reader may determine that: -　　a high-level of collisions are occurring between the A-IoT devices 3-1 such that attempts to perform RA procedures between the A-IoT devices 3-1 and the A-IoT reader are regularly failing; or -　　there is a low load (e.g., a number of A-IoT devices 3-1 that need to perform an RA procedure with the A-IoT device reader has reduced following some of the A-IoT devices 3-1 successfully completing an RA procedure).

[0282] In response to either of those determinations, the A-IoT device reader may decide to reconfigure the number of ROs available for performing an RA procedure between the A-IoT devices 3-1 and the A-IoT device reader (e.g., the IoT device reader may decide to reconfigure the Q value that it initially indicated to the A-IoT devices 3-1 in the (initial) RA trigger message / A-IoT paging message).

[0283] Thus at step S1415 the A-IoT device reader may send an appropriate (re)configuration message to the A-IoT devices 3-1 (e.g., a RO re-configuration message, or the like) to indicate to those A-IoT devices 3-1 a new (reconfigured) Q value 'Q2' wherein: -　　Q2 is greater than Q1 when the A-IoT device reader determines that a high-level of collisions are occurring between the A-IoT devices 3-1; or -　　Q2 is smaller than Q1 when the A-IoT device reader determines a number of A-IoT devices 3-1 that need to perform an RA procedure with the A-IoT device reader has reduced following some of the A-IoT devices 3-1 successfully completing an RA procedure.

[0284] Following receipt of the appropriate (re)configuration message at step S1415, each A-IoT device 3-1 that have not yet started an RA procedure with the A-IoT device reader may randomly re-select a new RO for performing a D2R transmission to the A-IoT device reader as part of an RA procedure (e.g., randomly select a new RO from the set of 2Q2ROs).

[0285] The steps S1416 to S1420 of Fig. 14 are similar to the steps S1316 to S1320 of Fig. 13. The description above of steps S1316 to S1320 is therefore generally applicable to the steps S1416 to S1420 respectively.

[0286] It will be appreciated that parameter Q1 and Q2 indicates corresponding 2Q1or 2Q1ROs to A-IoT devices 3-1 for random selection, but it may use another way to indicate the corresponding number of ROs to A-IoT devices 3-1 for random selection.

[0287] <Wake-up for A-IoT Paging and RA Procedures> 　　It will be appreciated that for all of the enhanced initial RA procedures for A-IoT described above with reference to Figs. 6 to 14, an appropriate procedure may need to be implemented prior to each one of those enhanced initial RA procedures to facilitate wake-up of the target A-IoT devices 3-1 that the A-IoT device reader wishes to page to trigger an RA procedure therebetween.

[0288] For example, it will be appreciated that due to the energy efficiency constraints of A-IoT devices 3-1 such devices may transition to a sleep state when they do not need to receive R2D transmission from an A-IoT device reader and / or transmit D2R transmissions to an A-IoT device reader. This being the case, the target A-IoT devices 3-1 will need to be woken-up prior to the A-IoT device reader paging them to perform an RA procedure.

[0289] Furthermore, following the completion of such RA procedures, appropriate procedures / triggers may be needed to transition the target A-IoT devices 3-1 back into a sleep state e.g., if they do not need to receive any further R2D transmissions from an A-IoT device reader and / or transmit further D2R transmissions to an A-IoT device reader.

[0290] Fig. 15 illustrates an example timing scheme for the transmission of an appropriate wake-up signal (WUS) to A-IoT devices 3-1 prior to a paging for triggering an RA procedure with an A-IoT device reader. As shown in Fig 15, having decided / determined that it wants to communicate with one or more A-IoT devices 3-1 (e.g., A-IoT device A to D), the A-IoT device reader may wish to send an (initial) RA trigger message / appropriate A-IoT paging message to target the A-IoT devices 3-1 as part of first paging round of a Paging 'A' in accordance with one of the procedures described above with reference to Figs. 6 to 14.

[0291] However, prior to sending the (initial) RA trigger message / appropriate A-IoT paging message to target A-IoT devices 3-1, the A-IoT device reader may first send an appropriate wake-up / activation message / signal (e.g., a WUS) to the all A-IoT devices 3-1 in its vicinity to wake-up those A-IoT devices 3-1. Alternatively, an appropriate wake-up / activation message / signal (e.g., a WUS) may be sent by the A-IoT device reader to the target A-IoT devices 3-1 together with the (initial) RA trigger message / appropriate A-IoT paging message sent to the target A-IoT devices 3-1. In this example, a single WUS is sent before (or at the start of) the first paging round of all paging rounds for a given paging (e.g., Paging 'A') (thus the WUS is common to all the corresponding paging rounds for the given paging (e.g., Paging 'A')).

[0292] The appropriate wake-up / activation message / signal (e.g., a WUS) may also take the form of a charging signal / carrier wave / strong stimulate signal to make sure all target A-IoT devices 3-1 are charged and awake.

[0293] As shown in Fig. 15, following transmission of the appropriate wake-up / activation message / signal (e.g., a WUS) by the A-IoT device reader to the A-IoT devices 3-1 in its vicinity, each A-IoT device 3-1 wakes up and listens for a paging message (e.g., an (initial) RA trigger message / appropriate A-IoT paging message). For example, as shown in Fig. 15, a first A-IoT device A may wake-up, listen, and not receive a paging (or it receives at paging that is not for A-IoT device A and thus can be ignored), while a second, third, and fourth A-IoT device B, C, and D may each wake-up, listen, and receive a paging.

[0294] The A-IoT devices 3-1 having been woken-up, may then be configured to transition back to a sleep state some (pre)configured time later based on one or more conditions. For example, in the case of A-IoT device A, having not received a paging (or it receives at paging that is not for A-IoT device A and thus can be ignored), the A-IoT device A may, after a (pre)configured period of time after wake-up, transitions back to a sleep state.

[0295] In the case of A-IoT devices B and C, having woken up and received a paging, after successfully responding to the paging and finishing all necessary inventory / reading / writing / command procedures (e.g., RA procedure), may be respectively sent, by the A-IoT reader, an appropriate indication to put A-IoT devices B and C into a sleep state. For example, an appropriate dedicated finish / sleep marker / signal may be respectively sent to each of A-IoT devices B and C (e.g. in a respective last R2D transmission to each of A-IoT devices B and C scheduled by the A-IoT device reader).

[0296] In the case of A-IoT device D, having woken up and received a paging, but failed to successfully perform an RA procedure with the A-IoT device reader after all possible paging rounds, the A-IoT device reader may send an appropriate finish / sleep signal / message to trigger A-IoT device D to transition back into a sleep state. Alternatively, the A-IoT device reader may send a last round indication signal at the end of the last paging round to implicitly indicate that any A-IoT devices 3-1 that have not received paging (e.g., A-IoT device D) should transition to a sleep state. or indicate that any awake A IoT devices 3-1 should transition to a sleep state.

[0297] It will be appreciated that a given A-IoT device 3-1 may be configured to temporarily enter a sleep state while waiting for its RO or for the next paging round.

[0298] Fig. 16 illustrates another example timing scheme for the transmission of an appropriate WUS to A-IoT devices prior to a paging for triggering an RA procedure with an A-IoT device reader.

[0299] As shown in Fig 16, having decided / determined that it wants to communicate with one or more A-IoT devices 3-1 (e.g., A-IoT device A to D), the A-IoT device reader may wish to send an (initial) RA trigger message / appropriate A-IoT paging message to target the A-IoT devices 3-1 as part of first paging round of a Paging 'A' in accordance with one of the procedures described above with reference to Figs. 6 to 14.

[0300] However, prior to sending the (initial) RA trigger message / appropriate A-IoT paging message to target A-IoT devices 3-1, the A-IoT device reader may first send an appropriate wake-up / activation message / signal (e.g., a WUS) to all A-IoT devices 3-1 in its vicinity to wake-up those A-IoT devices 3-1. Alternatively, an appropriate wake-up / activation message / signal (e.g., a WUS) may be sent by the A-IoT device reader to the target A-IoT devices 3-1 together with the initial) RA trigger message / appropriate A-IoT paging message sent to the target A-IoT devices 3-1. In this example, a plurality of WUSs may be sent, with a respective WUS being sent before (or at the start of) each paging round (or possibly every nthpaging round) for a given paging (e.g., Paging 'A') (thus each WUS is specific to a corresponding paging round (or a corresponding plurality of paging rounds) for the given paging (e.g., Paging 'A')).

[0301] The appropriate wake-up / activation message / signal (e.g., a WUS) may also take the form of a charging signal / carrier wave / strong stimulate signal to make sure all target A-IoT devices 3-1 are charged and awake.

[0302] As shown in Fig. 16, following transmission of the appropriate wake-up / activation message / signal (e.g., a WUS) by the A-IoT device reader to the A-IoT devices 3-1, each A-IoT device 3-1 wakes up and listens for a paging message (e.g., an (initial) RA trigger message / appropriate A-IoT paging message). For example, as shown in Fig. 16, a first A-IoT device A may wake-up, listen, and not receive a paging, while a second, third, and fourth A-IoT device B, C, and D may each wake-up, listen, and receive a paging.

[0303] The target A-IoT devices 3-1 having been woken-up, may then be configured to transition back to a sleep state some (pre)configured time later based on one or more conditions. For example, in the case of A-IoT device A, having not received a paging, the A-IoT device A may, after a (pre)configured period of time after wake-up, automatically transition back to a sleep state.

[0304] In the case of A-IoT device B, having woken up and received a paging in the first paging round, after it successfully responds to the paging and finishes all necessary inventory / reading / writing / command procedures (e.g., RA procedure) with the A-IoT device reader, the A-IoT reader may send an appropriate indication to that A-IoT device B put A-IoT device B into a sleep state. For example, an appropriate finish / sleep marker / signal dedicated to A-IoT device B may be included by the A-IoT device reader in a last R2D transmission to A-IoT device B scheduled by the A-IoT device reader.

[0305] In the case of A-IoT devices C and D, having woken up and received a paging, but then failed to successfully perform an RA procedure with the A-IoT device reader, may automatically transition back into a sleep state until the next paging round.

[0306] In the second paging round, as shown in Fig. 16, another WUS may be sent by the A-IoT device reader to the A-IoT devices 3-1, each A-IoT device 3-1 then wakes up again to listen for a paging message (e.g., an (initial) RA trigger message / appropriate A-IoT paging message). For example, as shown in Fig. 16, a first A-IoT device A may wake-up again, listen, and not receive a paging.

[0307] A-IoT device B, however, after waking up again, determines that it has already successfully received the corresponding paging in a previous paging round of that paging, and hence that it does not need to receive and respond to the paging. A-IoT device B may then automatically transition back into a sleep state.

[0308] In the case of A-IoT device C, after waking up again, successfully receives a paging. Then, after A-IoT device C successfully responds to the paging and finishes all necessary inventory / reading / writing / command procedures (e.g., RA procedure) with the A-IoT device reader, the A-IoT reader may send an appropriate indication to A-IoT device C to return A-IoT device C into the sleep state. For example, an appropriate finish / sleep marker / signal dedicated to A-IoT device C may be included by the A-IoT device reader in a last R2D transmission to A-IoT device C scheduled by the A-IoT device reader.

[0309] In the case of A-IoT device D, after waking up again and receiving a paging, but then failing to successfully perform an RA procedure with the A-IoT device reader, may automatically transition back into a sleep state until the next paging round.

[0310] <Adaptations to the Enhanced Initial RA Procedures for A-IoT> 　　It will be appreciated that for all of the enhanced initial RA procedures for A-IoT described above with reference to Figs. 6 to 14, appropriate adaptation may be made to those procedures minimize the wake-up / active time of A-IoT devices 3-1 in the vicinity of the A-IoT device reader that are not paged to provide energy savings in the communication system 1.

[0311] For example, the (initial) RA trigger messages / A-IoT paging messages described above with reference to the procedures of Figs. 6 to 14 may be separated into two distinct messages that are sent one after another: one paging message, and one RA trigger message.

[0312] In this scenario, it will be appreciated that the A-IoT devices 3-1 woken-up by a WUS in accordance with one of the procedure of either Fig. 15 or Fig. 16, may read the paging message after being woken-up and may determine whether the paging message is directed toward it or not. Each A-IoT device 3-1 that is not paged by the paging message may then decided to transition back into a sleep state and not monitor for the RA trigger message. At the same time, each A-IoT device 3-1 that is paged by the paging message may then monitor for the RA trigger message which may include the configuration of ROs scheduled by the A-IoT device reader for use by the A-IoT devices 3-1 in performing an RA procedure with the A-IoT device reader.

[0313] <Devices in the Communication System> <User Equipment> 　　Fig. 17 is a simplified block schematic illustrating the main components of a UE 3-2; 3-3 for implementation in the communication system 1. It will be appreciated that the UE 3-2; 3-3 may be configured to operate as an intermediate / assisting node 5-2 (i.e., and A-IoT device reader) in the communication system 1.

[0314] As shown, the UE 3-2; 3-3 has a transceiver circuit 31 that is operable to transmit signals to and to receive signals from a RAN node 5-1 via one or more antenna 33 (e.g., comprising one or more antenna elements). The UE 3-2; 3-3 has a controller 37 to control the operation of the UE 3-2; 3-3. The controller 37 is associated with a memory 39 and is coupled to the transceiver circuit 31. Although not necessarily required for its operation, the UE 3-2; 3-3 might, of course, have all the usual functionality of a conventional UE (e.g., a user interface 35, such as a touch screen / keypad / microphone / speaker and / or the like for, allowing direct control by and interaction with a user) and this may be provided by any one or any combination of hardware, software, and firmware, as appropriate. Software may be pre-installed in the memory 39 and / or may be downloaded via the communication system 1 or from a removable data storage device (RMD), for example.

[0315] The controller 37 is configured to control overall operation of the UE 3-2; 3-3 by, in this example, program instructions or software instructions stored within memory 39. As shown, these software instructions include, among other things, an operating system 41, and a communication control module 43.

[0316] The communication control module 43 is operable to control the communication between the UE 3-2; 3-3 and its serving RAN node or RAN nodes 5-1 (and other communication devices connected to the RAN node 5-1, such as further UEs 3 and / or core network nodes). The communication control module 43 is configured for the overall handling of uplink communication via associated uplink channels (e.g., via a physical uplink control channel (PUCCH), random access channel (RACH), and / or a physical uplink shared channel (PUSCH)) including both dynamic and semi-static signalling (e.g., SRS). The communication control module 43 is also configured for the overall handling of receipt of downlink communication via associated downlink channels (e.g., of DCI via a physical downlink control channel (PDCCH) and / or a physical downlink shared channel (PDSCH)) including both dynamic and semi-persistent scheduling (e.g., SPS). The communication control module 43 is responsible, for example: for determining where to monitor for downlink control information; for determining the resources to be used by the UE 3-2; 3-3 for transmission / reception of UL / DL communication (including interleaved resources and resources subject to frequency hopping); for managing frequency hopping at the UE side; for determining how slots / symbols are configured (e.g., for UL, DL or full duplex communication, or the like); for determining which bandwidth parts are configured for the UE 3-2; 3-3; for determining how uplink transmissions should be encoded and the like.

[0317] Where the UE 3-2, 3-3 is configured to operate as an intermediate / assisting node 5-2 (i.e., as an A-IoT device reader) the communication control module 43 may be operable to control the communication between the A-IoT device 3-1 and the UE 3-2, 3-3, for example, via the associated physical channels (e.g., via a physical D2R channel (PDRCH), random access channel (RACH), and / or a physical R2D channel (PRDCH)).

[0318] It will be appreciated that the communication control module 43 may include a number of sub-modules ('layers' or 'entities') to support specific functionalities. For example, the UE 3-2, 3-3 may include sub-modules corresponding to the layers of a conventional protocol stack (PHY, MAC, RRC, RLC, PDCP etc.). Moreover, where the UE 3-2, 3-3 is configured to operate as an intermediate / assisting node 5-2, communication control module 43 may include sub-modules corresponding to the layers of a dedicated ambient IoT device protocol stack for controlling functions associated with those layers.

[0319] The communication control module 43 is configured, in particular, to control the UE's communication, where applicable, in accordance with any of the methods described herein.

[0320] <Ambient IoT device> 　　Fig. 18 is a simplified block schematic illustrating the main components of an example of a UE comprising an ambient IoT device 3-1 for possible implementation in the communication system 1 of Fig. 1.

[0321] As shown, the ambient IoT device 3-1 (also referred to simply as an A-IoT device 3-1) has a transceiver circuit 331 that is operable to transmit signals to and to receive signals from a RAN node 5-1 (and / or an assisting node 5-2, and / or an intermediate node 5-2) via one or more antenna 333 (e.g., comprising one or more antenna elements).

[0322] The transceiver circuit 331 may comprise energy harvesting circuitry 331-1 that is configured to harvest and / or collect energy from an ambient energy source such as an incoming signal and / or other ambient sources of energy (e.g., of light, vibrations, or heat). That collected energy may then be provided to other modules of A-IoT device 3-1 to provide a stable power supply to those modules. The energy harvesting circuitry 331-1 may include, by way of example only, inductive and / or capacitive architectures to harvest energy from incoming signals.

[0323] It will however be appreciated that the energy harvesting circuitry 331-1 may alternatively not form part of the transceiver circuit 331, but instead is its own module. For example, this may be the case when the energy to be harvested does not originate from signals transmitted to the A-IoT device 3-1. By way of example only, the A-IoT device 3-1 may harvest energy from solar cells such as dye-sensitised solar cells (DSSCs).

[0324] The transceiver circuit 331 also has modulation circuitry 331-2 which modulates an incoming unmodulated carrier signal to the A-IoT device 3-1 to produce the modulated backscatter signal to be reflected from the A-IoT device 3-1 for receipt by another device. For example, the modulation circuitry 331-2 may be configured modulate an incoming RF signal to the A-IoT device 3-1 by altering the impedance or reflectivity of the A-IoT device 3-1 in response to receiving that incoming RF signal. The modulation circuitry 331-2 may be configured to modulate the incoming signal to encode data provided from one or more data sources 332. Typically, for example, the A-IoT device 3-1 may comprise a data source 332 in the form of a sensor (e.g., an optical, temperature, position sensor or the like) for providing measurement data or a sensor alert, may comprise a data source 332 in the form of a stored or hardwired parameter such as a device or device type identifier, and / or may comprise one or more other sources of data. In this example, the transceiver circuit 331 may also have a signal amplifier 331-3 (which may utilise energy harvested by the energy harvesting circuitry 331-1) for amplifying any modulated backscattered signal to be reflected by the A-IoT device 3-1 for receipt at another device.

[0325] In this example, the A-IoT device 3-1 also has a controller 337 to control the overall operation of the A-IoT device 3-1. The controller 337 is associated with a memory 339 and is coupled to the transceiver circuit 331. Although not necessarily required for its operation, the A-IoT device 3-1 might, of course, have all the usual functionality of a more conventional UE (e.g., a user interface 335, such as a touch screen / keypad / microphone / speaker and / or the like for, allowing direct control by and interaction with a user) and this may be provided by any one or any combination of hardware, software, and firmware, as appropriate. Software may be pre-installed in the memory 339 and / or may be downloaded via the communication system 1 or from a removable data storage device (RMD), for example.

[0326] The controller 337 is configured to control overall operation of the A-IoT device 3-1 by, in this example, program instructions or software instructions stored within memory 339. As shown, these software instructions include, among other things, an operating system 341, and a communication control module 343.

[0327] The communication control module 343 is operable to control the communication between the A-IoT device 3-1, a RAN node 5-1, and / or an assisting node 5-2. The communication control module 343 may, for example, be configured for the overall handling of communication via associated physical channels (e.g., via a physical D2R channel (PDRCH), random access channel (RACH), and / or a physical R2D channel (PRDCH)).

[0328] It will be appreciated that the communication control module 343 may include a number of sub-modules ('layers' or 'entities') to support specific functionalities. For example, the communication control module 343 may include sub-modules corresponding to the layers of a dedicated ambient IoT device protocol stack for controlling functions associated with those layers.

[0329] The communication control module 343 is configured, in particular, to control the IoT device's communication, where applicable, in accordance with any of the methods described herein.

[0330] <RAN node> 　　Fig. 19 is a simplified block schematic illustrating the main components of a RAN node 5-1 (e.g., a base station / A-IoT device reader) for implementation in the communication system 1 of Fig. 1. It will be appreciated that the RAN node 5-1 may be configured to operate as an A-IoT device reader in the communication system 1.

[0331] As shown, the RAN node 5-1 has a transceiver circuit 51 for transmitting signals to and for receiving signals from the communication devices (such as UEs 3-2; 3-3, A-IoT devices 3-1, and possibly assisting or intermediate devices 5-2) via one or more antenna 53 (e.g., a single or multi-panel antenna array / massive antenna), and a core network interface 55 for transmitting signals to and for receiving signals from network nodes in the core network 7. Although not shown, the RAN node 5-1 may also be coupled to other base stations via an appropriate interface (e.g., the so-called 'X2' interface in LTE or the 'Xn' interface in NR). The RAN node 5-1 has a controller 57 to control the operation of the base station 5-1. The controller 57 is associated with a memory 59. Software may be pre-installed in the memory 59 and / or may be downloaded via the communication system 1 or from a removable data storage device (RMD), for example. The controller 57 is configured to control the overall operation of the RAN node 5-1 by, in this example, program instructions or software instructions stored within memory 59.

[0332] As shown, these software instructions include, among other things, an operating system 61, and a communication control module 63.

[0333] The communication control module 63 is operable to control the communication between the RAN node 5-1 and UEs 3 and other network entities (e.g., core network nodes) that communicate with the base station 5. The communication control module 63 is configured for the overall control of the reception and decoding of uplink communication, via associated uplink channels (e.g., via a physical uplink control channel (PUCCH), a random access channel (RACH), and / or a physical uplink shared channel (PUSCH)) including both dynamic and semi-static signalling (e.g., SRS), and modulated backscattered communication in accordance with ambient IoT (where applicable). The communication control module 63 is also configured for the overall control of the transmission of downlink communication including downlink communication via associated downlink channels (e.g., via a physical downlink control channel (PDCCH) and / or a physical downlink shared channel (PDSCH)) including both dynamic and semi-persistent scheduling (e.g., SPS), and downlink communication of an unmodulated carrier signal in accordance with ambient IoT (where applicable). The communication control module 63 is responsible, for example: for determining where to configure the UE 3 to monitor for downlink control information (e.g., the location of search spaces, CORESETs, and associated PDCCH candidates to monitor); for determining the resources to be scheduled for UE transmission / reception of UL / DL communication (including interleaved resources and resources subject to frequency hopping); for managing frequency hopping at the base station side; for configuring slots / symbols appropriately (e.g., for UL, DL or full duplex communication, or the like); for configuring bandwidth parts for the UE 3; for providing related configuration signalling to a UE 3; and the like.

[0334] Where the RAN node 5-1 is configured to operate as an A-IoT device reader the communication control module 63 is operable to control the communication between the A-IoT device 3-1 and the RAN node 5-1, for example, via the associated physical channels (e.g., via a physical D2R channel (PDRCH), random access channel (RACH), and / or a physical R2D channel (PRDCH)) including both dynamic and semi-static signalling. It will be appreciated that the communication control module 63 may include a number of sub-modules ('layers' or 'entities') to support specific functionalities. By way of example only the communication control module 63 may include sub-modules corresponding to the layers of a conventional protocol stack (PHY, MAC, RRC, RLC, PDCP etc.). Moreover, where the RAN node 5-1 is configured to operate as an A-IoT device reader, the communication control module 63 may include, sub-modules corresponding to the layers of a dedicated ambient IoT device protocol stack for controlling functions associated with those layers.

[0335] The communication control module 63 is configured in particular, to control the base station's communication, in accordance with any of the methods described herein.

[0336] <Assisting (or intermediate) node> 　　Fig. 20 is a simplified block schematic illustrating the main components of an example of an assisting (or intermediate) node 5-2 for possible implementation in the communication system 1 of Fig. 1.

[0337] As shown, the assisting node 5-2 may comprise a UE 3 (such as, or similar to, UE 3-2; 3-3), an IAB node, a repeater, or the like, which is capable of ambient IoT operation. In this scenario, the assisting node 5-2 has a transceiver circuit 151 that is operable to transmit signals to and to receive signals from a UE 3 (such as an A-IoT device 3-1) via one or more antenna 153 (e.g., comprising one or more antenna elements), and a RAN interface 155 for transmitting signals to and for receiving signals from the RAN node 5-1 (which may also be over the air via the antenna 153, or via a different antenna).

[0338] The assisting node 5-2 has a controller 157 to control the operation of the assisting node 5-2. The controller 157 is associated with a memory 159 and is coupled to the transceiver circuit 151. Although not necessarily required for its operation, the assisting node 5-2 might, of course, have other functionality (e.g., a user interface, such as a touch screen / keypad / microphone / speaker and / or the like for, allowing direct control by and interaction with a user) and this may be provided by any one or any combination of hardware, software, and firmware, as appropriate. Software may be pre-installed in the memory 159 and / or may be downloaded via the communication system 1 or from a removable data storage device (RMD), for example.

[0339] The controller 157 is configured to control overall operation of the UE 3 by, in this example, program instructions or software instructions stored within memory 159. As shown, these software instructions include, among other things, an operating system 161, and a communication control module 163.

[0340] The communication control module 163 is operable to control the communication between the assisting node 5-2, the RAN node 5-1, and any IoT devices (including the A-IoT device 3-1). The communication control module 163 is configured, in particular, for the overall handling of communication with the RAN node 5-1. For example, where the intermediate / assisting node 5-2 is a UE 3 (or at least operates like a UE in its communication with the RAN node 5-1) this uplink communication may be via associated uplink channels (e.g., via a physical uplink control channel (PUCCH), random access channel (RACH), and / or a physical uplink shared channel (PUSCH)) including both dynamic and semi-static signalling (e.g., SRS). The communication control module 163 is also configured for the overall handling of receipt of downlink communication from the RAN node 5-1. For example, where the intermediate / assisting node 5-2 is a UE 3 (or at least operates like a UE in its communication with the RAN node 5-1) this downlink communication may be via associated downlink channels (e.g., of DCI via a physical downlink control channel (PDCCH) and / or a physical downlink shared channel (PDSCH)) including both dynamic and semi-persistent scheduling (e.g., SPS). It will, nevertheless, be appreciated that where the assisting node 5-2 is a device other than a UE (e.g., an IAB or dedicated relay) then the communication control module 163 will be configured to communicate with the RAN node 5-1 using an appropriate corresponding signalling protocol for doing so.

[0341] The communication control module 163 is also responsible for appropriate ambient IoT related communication including, for example, reception of modulated backscattered communication from an ambient IoT device (where applicable) and / or downlink communication of an unmodulated carrier signal in accordance with ambient IoT (where applicable).

[0342] It will be appreciated that the communication control module 163 may include a number of sub-modules ('layers' or 'entities') to support specific functionalities. By way of example only the communication control module 163 may include sub-modules corresponding to the layers of a conventional protocol stack (PHY, MAC, RRC, RLC, PDCP etc.). Moreover, the communication control module 163 may include, sub-modules corresponding to the layers of a dedicated ambient IoT device protocol stack for controlling functions associated with those layers.

[0343] The communication control module 163 is configured, in particular, to control the assisting node's communication, in accordance with any of the methods described herein.

[0344] <Modifications and Alternatives> 　　Detailed examples been described above. As those skilled in the art will appreciate, a number of modifications and alternatives can be made to the above examples whilst still benefiting from the enhancements embodied therein.

[0345] It will be appreciated that description of features of and actions performed by a RAN node (base station), apply equally to distributed type base stations as to non-distributed type base stations.

[0346] It will also be appreciated that whilst information elements having specific names have been described differently named information elements but having a similar purpose may be used.

[0347] In the above description the UE and the base station are described for ease of understanding as having a number of discrete functional components or modules. Whilst these modules may be provided in this way for certain applications, for example where an existing system has been modified to implement the disclosed enhancements, in other applications, for example in systems designed with the inventive features in mind from the outset, these modules may be built into the overall operating system or code and so these modules may not be discernible as discrete entities.

[0348] In the above examples, a number of software modules were described. As those skilled in the art will appreciate, the software modules may be provided in compiled or un-compiled form and may be supplied to the UE or base station as a signal over a computer network, or on a recording medium. Further, the functionality performed by part, or all, of this software may be performed using one or more dedicated hardware circuits. However, the use of software modules is preferred as it facilitates the updating of the UE or the base station in order to update their functionalities.

[0349] Each controller may comprise any suitable form of processing circuitry including (but not limited to), for example: one or more hardware implemented computer processors; microprocessors; central processing units (CPUs); arithmetic logic units (ALUs); input / output (IO) circuits; internal memories / caches (program and / or data); processing registers; communication buses (e.g. control, data and / or address buses); direct memory access (DMA) functions; hardware or software implemented counters, pointers and / or timers; and / or the like. Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

[0350] The User Equipment (or "UE," "mobile station," "mobile device" or "wireless device") in the present disclosure is an entity connected to a network via a wireless interface.

[0351] It should be noted that the present disclosure is not limited to a dedicated communication device and can be applied to any device having a communication function as explained in the following paragraphs.

[0352] The terms "User Equipment" or "UE" (as the term is used by 3GPP), "mobile station", "mobile device", and "wireless device" are generally intended to be synonymous with one another, and include standalone mobile stations, such as terminals, cell phones, smart phones, tablets, cellular IoT devices, IoT devices, and machinery. It will be appreciated that the terms "mobile station" and "mobile device" also encompass devices that remain stationary for an extended period of time.

[0353] A UE may, for example, be an item of equipment for production or manufacture and / or an item of energy related machinery (for example equipment or machinery such as: boilers; engines; turbines; solar panels; wind turbines; hydroelectric generators; thermal power generators; nuclear electricity generators; batteries; nuclear systems and / or associated equipment; heavy electrical machinery; pumps including vacuum pumps; compressors; fans; blowers; oil hydraulic equipment; pneumatic equipment; metal working machinery; manipulators; robots and / or their application systems; tools; moulds or dies; rolls; conveying equipment; elevating equipment; materials handling equipment; textile machinery; sewing machines; printing and / or related machinery; paper converting machinery; chemical machinery; mining and / or construction machinery and / or related equipment; machinery and / or implements for agriculture, forestry and / or fisheries; safety and / or environment preservation equipment; tractors; precision bearings; chains; gears; power transmission equipment; lubricating equipment; valves; pipe fittings; and / or application systems for any of the previously mentioned equipment or machinery etc.).

[0354] A UE may, for example, be an item of transport equipment (for example transport equipment such as: rolling stocks; motor vehicles; motorcycles; bicycles; trains; buses; carts; rickshaws; ships and other watercraft; aircraft; rockets; satellites; drones; balloons etc.).

[0355] A UE may, for example, be an item of information and communication equipment (for example information and communication equipment such as: electronic computer and related equipment; communication and related equipment; electronic components etc.).

[0356] A UE may, for example, be a refrigerating machine, a refrigerating machine applied product, an item of trade and / or service industry equipment, a vending machine, an automatic service machine, an office machine or equipment, a consumer electronic and electronic appliance (for example a consumer electronic appliance such as: audio equipment; video equipment; a loud speaker; a radio; a television; a microwave oven; a rice cooker; a coffee machine; a dishwasher; a washing machine; a dryer; an electronic fan or related appliance; a cleaner etc.).

[0357] A UE may, for example, be an electrical application system or equipment (for example an electrical application system or equipment such as: an x-ray system; a particle accelerator; radio isotope equipment; sonic equipment; electromagnetic application equipment; electronic power application equipment etc.).

[0358] A UE may, for example, be an electronic lamp, a luminaire, a measuring instrument, an analyser, a tester, or a surveying or sensing instrument (for example a surveying or sensing instrument such as: a smoke alarm; a human alarm sensor; a motion sensor; a wireless tag etc.), a watch or clock, a laboratory instrument, optical apparatus, medical equipment and / or system, a weapon, an item of cutlery, a hand tool, or the like.

[0359] A UE may, for example, be a wireless-equipped personal digital assistant or related equipment (such as a wireless card or module designed for attachment to or for insertion into another electronic device (for example a personal computer, electrical measuring machine)).

[0360] A UE may be a device or a part of a system that provides applications, services, and solutions described below, as to "internet of things (IoT)," using a variety of wired and / or wireless communication technologies.

[0361] Internet of Things devices (or "things") may be equipped with appropriate electronics, software, sensors, network connectivity, and / or the like, which enable these devices to collect and exchange data with each other and with other communication devices. IoT devices may comprise automated equipment that follow software instructions stored in an internal memory. IoT devices may operate without requiring human supervision or interaction. IoT devices might also remain stationary and / or inactive for an extended period of time. IoT devices may be implemented as a part of a (generally) stationary apparatus. IoT devices may also be embedded in non-stationary apparatus (e.g., vehicles) or attached to animals or persons to be monitored / tracked.

[0362] It will be appreciated that IoT technology can be implemented on any communication devices that can connect to a communication system for sending / receiving data, regardless of whether such communication devices are controlled by human input or software instructions stored in memory.

[0363] It will be appreciated that IoT devices are sometimes also referred to as Machine-Type Communication (MTC) devices or Machine-to-Machine (M2M) communication devices. It will be appreciated that a UE may support one or more IoT or MTC applications. Some examples of MTC applications are listed in the following table. This list is not exhaustive and is intended to be indicative of some examples of machine type communication applications.

[0364] Further, the above-described UE categories are merely examples of applications of the technical ideas and exemplary examples described in the present document. Needless to say, these technical ideas and examples are not limited to the above-described UE and various modifications can be made thereto.

[0365] Various other modifications will be apparent to those skilled in the art and will not be described in further detail here.

[0366] For example, the whole or part of the exemplary embodiments disclosed above can be described as, but not limited to, the following supplementary notes. 　　(Supplementary note 1) 　　A method performed by a mobile device configured to trigger a random access procedure by receiving a paging message, the method comprising: 　　receiving, from a reader device, a paging message including identity information indicating a transaction of the random access procedure; 　　determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure. 　　(Supplementary note 2) 　　The method according to supplementary note 1, wherein 　　the paging message includes device information indicating which mobile devices are selected for triggering the random access procedure, and 　　the determining is performed based on whether the device information indicates the mobile device. 　　(Supplementary note 3) 　　The method according to supplementary note 1 or 2, wherein 　　the paging message includes scheduling information for resources for the random access procedure, and the method comprises: 　　triggering the random access procedure using the resources indicated by the scheduling information. 　　(Supplementary note 4) 　　The method according to supplementary note 1 or 2, further comprising: 　　receiving, from the reader device, information scheduling information for resources for the random access procedure; and 　　triggering the random access procedure using the resources indicated by the scheduling information. 　　(Supplementary note 5) 　　The method according to supplementary note 3 or 4, wherein 　　the scheduling information includes information indicating a number of random access channel occasions (ROs), and 　　the triggering the random access is performed based on the number of the ROs. 　　(Supplementary note 6) 　　The method according to supplementary note 5, wherein 　　the scheduling information includes information indicating the number of ROs for each of a plurality of paging messages. 　　(Supplementary note 7) 　　The method according to supplementary note 6, further comprising: 　　receiving, from the reader device, reconfiguration message for reconfiguring the number of the ROs for the each of the plurality of the paging messages. 　　(Supplementary note 8) 　　The method according to supplementary note 1 or 2, further comprising: 　　triggering the random access procedure using resources selected from a shared random access channel occasions (ROs). 　　(Supplementary note 9) 　　The method according to any one of supplementary notes 3 to 8, wherein 　　the triggering the random access procedure is performed after a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure. 　　(Supplementary note 10) 　　The method according to any one of supplementary notes 1 to 9, wherein 　　in a case where the mobile device is in a specific status, not triggering the random access procedure in response to the determining that the mobile device has been selected. 　　(Supplementary note 11) 　　The method according to any one of supplementary notes 1 to 10, wherein 　　the receiving the paging message is performed in a case where the mobile device has been activated for receiving the paging message. 　　(Supplementary note 12) 　　The method according to supplementary note 11, further comprising: 　　receiving, from the reader device, information causing the mobile device to activate for receiving the paging message. 　　(Supplementary note 13) 　　The method according to supplementary note 12, wherein 　　the information causing the mobile device to activate is received together with the paging message. 　　(Supplementary note 14) 　　The method according to supplementary note 12 or 13, wherein 　　the information causing the mobile device to activate is received per paging message. 　　(Supplementary note 15) 　　A method performed by a reader device configured to cause a mobile device to trigger a random access procedure by transmitting a paging message, the method comprising: 　　transmitting, to a mobile device, a paging message including identity information indicating a transaction of the random access procedure, and wherein 　　the identity information is used by the mobile device in determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure. 　　(Supplementary note 16) 　　A mobile device configured to trigger a random access procedure by receiving a paging message, the mobile device comprising: 　　means for receiving, from a reader device, a paging message including identity information indicating a transaction of the random access procedure; 　　means for determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure. 　　(Supplementary note 17) 　　A reader device configured to cause a mobile device to trigger a random access procedure by transmitting a paging message, the reader device comprising: 　　means for transmitting, to a mobile device, a paging message including identity information indicating a transaction of the random access procedure, and wherein 　　the identity information is used by the mobile device in determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

[0367] This application is based upon and claims the benefit of priority from Great Britain Patent Application No. 2411649.3, filed on August 7, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0368] 1 COMMUNICATION SYSTEM 3 USER EQUIPMENT 5 BASE STATION 7 CORE NETWORK 9 CELL 10 CONTROL PLANE FUNCTIONS 11 USER PLANE FUNCTIONS 21 EXTERNAL DATA NETWORK 31 TRANSCEIVER CIRCUIT 33 ANTENNA 35 USER INTERFACE 37 CONTROLLER 39 MEMORY 41 OPERATING SYSTEM 43 COMMUNICATIONS CONTROL MODULE 331 TRANSCEIVER CIRCUIT 331-1 ENERGY HARVESTING CIRCUITRY 331-2 MODULATION CIRCUITRY 331-3 SIGNAL AMPLIFIER 332 DATA SOURCE 333 ANTENNA 335 USER INTERFACE 337 CONTROLLER 338 PROCESSING CIRCUITRY 339 MEMORY 341 OPERATING SYSTEM 343 COMMUNICATIONS CONTROL MODULE 345 DATA BUFFER 51 TRANSCEIVER CIRCUIT 53 ANTENNA 55 CORE NETWORK INTERFACE 57 CONTROLLER 59 MEMORY 61 OPERATING SYSTEM 63 COMMUNICATIONS CONTROL MODULE 151 TRANSCEIVER CIRCUIT 153 ANTENNA 155 RAN INTERFACE 157 CONTROLLER 159 MEMORY 161 OPERATING SYSTEM 163 COMMUNICATIONS CONTROL MODULE

Claims

1. A method performed by a mobile device configured to trigger a random access procedure by receiving a paging message, the method comprising: 　　receiving, from a reader device, a paging message including identity information indicating a transaction of the random access procedure; 　　determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

2. The method according to claim 1, wherein 　　the paging message includes device information indicating which mobile devices are selected for triggering the random access procedure, and 　　the determining is performed based on whether the device information indicates the mobile device.

3. The method according to claim 1 or 2, wherein 　　the paging message includes scheduling information for resources for the random access procedure, and the method comprises: 　　triggering the random access procedure using the resources indicated by the scheduling information.

4. The method according to claim 1 or 2, further comprising: 　　receiving, from the reader device, information scheduling information for resources for the random access procedure; and 　　triggering the random access procedure using the resources indicated by the scheduling information.

5. The method according to claim 3 or 4, wherein 　　the scheduling information includes information indicating a number of random access channel occasions (ROs), and 　　the triggering the random access is performed based on the number of the ROs.

6. The method according to claim 5, wherein 　　the scheduling information includes information indicating the number of ROs for each of a plurality of paging messages.

7. The method according to claim 6, further comprising: 　　receiving, from the reader device, reconfiguration message for reconfiguring the number of the ROs for the each of the plurality of the paging messages.

8. The method according to claim 1 or 2, further comprising: 　　triggering the random access procedure using resources selected from a shared random access channel occasions (ROs).

9. The method according to any one of claims 3 to 8, wherein 　　the triggering the random access procedure is performed after a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

10. The method according to any one of claims 1 to 9, wherein 　　in a case where the mobile device is in a specific status, not triggering the random access procedure in response to the determining that the mobile device has been selected.

11. The method according to any one of claims 1 to 10, wherein 　　the receiving the paging message is performed in a case where the mobile device has been activated for receiving the paging message.

12. The method according to claim 11, further comprising: 　　receiving, from the reader device, information causing the mobile device to activate for receiving the paging message.

13. The method according to claim 12, wherein 　　the information causing the mobile device to activate is received together with the paging message.

14. The method according to claim 12 or 13, wherein 　　the information causing the mobile device to activate is received per paging message.

15. A method performed by a reader device configured to cause a mobile device to trigger a random access procedure by transmitting a paging message, the method comprising: 　　transmitting, to a mobile device, a paging message including identity information indicating a transaction of the random access procedure, and wherein 　　the identity information is used by the mobile device in determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

16. A mobile device configured to trigger a random access procedure by receiving a paging message, the mobile device comprising: 　　means for receiving, from a reader device, a paging message including identity information indicating a transaction of the random access procedure; 　　means for determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

17. A reader device configured to cause a mobile device to trigger a random access procedure by transmitting a paging message, the reader device comprising: 　　means for transmitting, to a mobile device, a paging message including identity information indicating a transaction of the random access procedure, and wherein 　　the identity information is used by the mobile device in determining that the mobile device has been selected for triggering the random access procedure in a case where: 　　　　the identity information is different from previous identity information stored by the mobile device, or 　　　　a previous random access procedure corresponding to the previous identity information stored by the mobile device was considered as a failure.

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