Methods, communications devices, readers, and wireless communications systems

Abstract

A method of operating a communications device (101) configured to harvest energy from one or more ambient sources and to communicate with one or more readers (102, 103) of a communications system is provided. The method comprises receiving, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader (102), receiving, from a second reader (103) during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and responding either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

Description

[0001] METHODS, COMMUNICATIONS DEVICES, READERS, AND WIRELESS COMMUNICATIONS SYSTEMS

[0002] BACKGROUND

[0003] Field of Disclosure

[0004] The present disclosure relates to communications devices, infrastructure equipment, and methods for the more efficient and effective operation of low power devices in a wireless communications network.

[0005] The present application claims the Paris Convention priority from European patent application number EP24187532.7, filed on 9 July 2024, the contents of which are hereby incorporated by reference.

[0006] Description of Related Art

[0007] The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present invention.

[0008] Previous generation mobile telecommunication systems, such as those based on the 3GPP defined UMTS and Long Term Evolution (LTE) architecture, are able to support a wider range of services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE systems, a user is able to enjoy high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. The demand to deploy such networks is therefore strong and the coverage area of these networks, i.e. geographic locations where access to the networks is possible, is expected to continue to increase rapidly.

[0009] Current and future wireless communications networks are expected to routinely and efficiently support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types than existing systems are optimised to support. For example, it is expected future wireless communications networks will be expected to efficiently support communications with devices including reduced complexity devices, machine type communication (MTC) devices, high resolution video displays, virtual reality headsets, extended Reality (XR) and so on. Some of these different types of devices may be deployed in very large numbers, for example low complexity devices for supporting the “The Internet of Things”, and may typically be associated with the transmissions of relatively small amounts of data with relatively high latency tolerance. Other types of device, for example supporting high-definition video streaming, may be associated with transmissions of relatively large amounts of data with relatively low latency tolerance. Other types of device, for example used for autonomous vehicle communications and for other critical applications, may be characterised by data that should be transmitted through the network with low latency and high reliability. A single device type might also be associated with different traffic profiles / characteristics depending on the application(s) it is running. For example, different considerations may apply for efficiently supporting data exchange with a smartphone when it is running a video streaming application (high downlink data) as compared to when it is running an Internet browsing application (sporadic uplink and downlink data) or being used for voice communications by an emergency responder in an emergency scenario (data subject to stringent reliability and latency requirements).

[0010] In view of this there is expected to be a desire for current wireless communications networks, for example those which may be referred to as 5G or new radio (NR) systems / new radio access technology (RAT) systems, or indeed future 6G wireless communications, as well as future iterations / releases of existing systems, to efficiently support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements.

[0011] SUMMARY OF THE DISCLOSURE

[0012] The present disclosure can help address or mitigate at least some of the issues discussed above.

[0013] At least some embodiments of the present technique can provide a method of operating a communications device configured to harvest energy from one or more ambient sources and to communicate with one or more readers of a communications system. The method comprises receiving, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, receiving, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and responding either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

[0014] Such embodiments of the present technique, which, in addition to methods of operating communications devices, relate to methods of operating readers, to communications devices and readers, to circuitry for communications devices and readers, to wireless communications systems, to computer programs, and to computer-readable storage mediums, can allow for the more efficient and effective operation of low power devices in wireless communications networks by better defining the behaviour of such devices when receiving paging-like messages triggering the performance of access procedures with such wireless communications networks.

[0015] Respective aspects and features of the present disclosure are defined in the appended claims.

[0016] It is to be understood that both the foregoing general description and the following detailed description are exemplary, but are not restrictive, of the present technology. The described embodiments, together with further advantages, will be best understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

[0017] BRIEF DESCRIPTION OF THE DRAWINGS

[0018] A more complete appreciation of the disclosure and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein like reference numerals designate identical or corresponding parts throughout the several views, and wherein:

[0019] Figures 1A and IB schematically represent examples of communication systems in which tags are deployed within a coverage area of an infrastructure equipment (e.g. a gNB) of a wireless communications network and in which carrier wave emitters are controlled by the infrastructure equipment to transmit carrier wave signals and backscattered signals are detected;

[0020] Figure 2 schematically represents some aspects of a new radio access technology (RAT) wireless telecommunications system which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0021] Figure 3 is a schematic block diagram of an example infrastructure equipment and communications device which may be configured to operate in accordance with certain embodiments of the present disclosure;

[0022] Figure 4 is a schematic block diagram illustrating an example of backscattering circuitry; Figure 5 is a schematic illustration representing an example in which a carrier wave signal transmitted by an external carrier wave emitter is backscattered;

[0023] Figure 6 schematically illustrates an example of an ambient loT device communicating with a network; Figures 7A and 7B schematically illustrates examples of an ambient loT device communicating with a network;

[0024] Figure 8 illustrates an example of a contention-based access procedure for ambient loT devices; Figure 9 shows how an ambient loT device can be located between and thus receive paging-like triggering messages from multiple readers;

[0025] Figure 10 shows a part schematic, part message flow diagram representation of an example wireless communications system comprising a communications device and an infrastructure equipment in accordance with embodiments of the present technique;

[0026] Figure 11 illustrates an example of a timing structure comprising multiple access rounds and engaging periods in accordance with embodiments of the present technique; and

[0027] Figure 12 shows a flow diagram illustrating an example process of communications in a communications system in accordance with embodiments of the present technique.

[0028] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] Ambient Internet of Things (loT)

[0030] In Release 19 of 3GPP (Rel-19), 3GPP will study Ambient loT (A-IoT, AIoT) [1,2], where a communications device (such as a UE) is essentially a zero power communications device. In Ambient loT, it is considered that the communications device can harvest energy to power its communication with a base station (such as a gNB). For example, the energy can be harvested from solar or kinetic energy such as vibrations. Alternatively, the energy to power the communications device can come from incident radio frequency (RF) energy, either directly from a base station or from a carrier wave emitter (CWE). An example in which such communication devices are powered by radio frequency energy derived from radio signals transmitted as a carrier wave (CW) by a CWE is shown in Figures 1A and IB. Figures 1A and IB show a plurality of low-complexity communications devices 1, which can be deployed in accordance with an ambient loT scenario. These low-complexity communications devices 1 can be referred to as “tags” because of the simplicity of such devices. These tags 1 are powered as a result of radio frequency energy received from an incident CW 2 transmitted by the CWE 3.

[0031] In a first example illustrated by Figure 1A, a base station 4, or gNB 4 according to 3GPP 5G terminology, receives a backscattered signal 5 from the tags 1, the backscattered signal 5 being formed as a reflection of the carrier wave 2 transmitted by the CWE 3.

[0032] In a second example illustrated by Figure IB, a UE 7 receives a backscattered signal 5 from the tags 1. The UE 7 then transmits an indication of the received backscattered signals 5, which were received from the tags 1, to the gNB 4 via a wireless access interface 8 formed between the gNB 4 and the UE 7. Therefore, the gNB 4 may control the CWEs 3 to transmit the CWs 2, and the backscattered signals are detected by the detection station (i.e. the UE) 7, and the detection station transmits an indication of the detected backscattered signals to the gNB 4.

[0033] The station which controls the CWEs 3 may be regarded as a controller station. The station which detects the backscattered signals 5 may be regarded as detection station. The detection station may also be referred to as reader. Therefore, in the example of Figure 1A, both the controller station and the detection station are formed by the gNB 4. In contrast, in the example of Figure IB, the detection station 7 which is deployed in the form of the UE 7 is separate from the gNB 4 which acts as the controller station. According to the arrangements of Figures 1A and IB, the tags 1 may modulate the reflected or backscattered signal 5 with information which is detected by the gNB 4 or a UE 7 acting as a detection station. As shown in Figures 1A and IB, gNB 4, which provides a cell represented by dashed line 12, controls CWE 3 to transmit CW 2.

[0034] In some examples, the CWE 3 is formed by a communications device (such as a UE) which operates with a wireless communications network of which the gNB 4 forms part. The gNB 4 has an interface 6 to the CWE 3. In some examples therefore the interface 6 may be a Uu interface, using 3GPP terminology. In some examples, the CWE is part of the gNB 4. In this case, the interface 6 can be an internal interface to the gNB 4. The CWE 3 can be a standalone device or can be part of another network node. In one example, the CWE is a UE, such as a legacy UE or smartphone. In this case, the UE can be controlled to send a suitable signal to act as a carrier wave signal. It is also possible for the AIoT device to transmit data in the uplink by backscattering another signal (for example the DL signal from the gNB 4).

[0035] In some examples, such as the example of Figure IB, the backscattered signal 5 may be received by a separate detection station (e.g. UE 7) which does not form part of the gNB 4. However since example embodiments can operate within or in association with wireless communications networks, an architecture of a typical 5G or New Radio (NR) wireless communications network will be now be described with reference to Figures 2 and 3. In some examples the CWE 3 may be incorporated within the detection station as a reader, in that the reader both emits the carrier wave signals and detects the backscattered signal from the one or more tags. The reader may then send the decoded information to the controller station.

[0036] New Radio Access Technology (5G)

[0037] An example configuration of a wireless communications network which uses some of the terminology proposed for and used in NR and 5G is shown in Figure 2. In Figure 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a circle 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. Each CU may be connected to a single DU, or a CU may be connected to multiple DUs as is the case for CU 40 in the example of Figure 2. The central unit 40 is then connected to the core network 20 which may contain all other functions required to transmit data for communicating to and from the wireless communications devices and the core network 20 may be connected to other networks 25.

[0038] The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2, and of other networks discussed herein in accordance with embodiments of the disclosure, which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards. The TRPs 10 of Figure 2 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. Similarly, the communications devices 14 may have a functionality corresponding to the UE devices 4 known for operation with an LTE network. It will be appreciated therefore that operational aspects of a new RAT network (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be different to those known from LTE or other known mobile telecommunications standards. However, it will also be appreciated that each of the core network component, base stations and communications devices of a new RAT network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network.

[0039] In terms of broad top-level functionality, the core network 20 connected to the new RAT telecommunications system represented in Figure 2 may be broadly considered to correspond with an LTE core network, and the respective central units 40 and their associated distributed units / TRPs 10 may be broadly considered to provide functionality corresponding to LTE base stations. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the controlling node / central unit and / or the distributed units / TRPs. A communications device 14 is represented in Figure 2 within the coverage area of the first communication cell 12. This communications device 14 may thus exchange signalling with the first central unit 40 in the first communication cell 12 via one of the distributed units / TRPs 10 associated with the first communication cell 12.

[0040] It will further be appreciated that Figure 2 represents merely one example of a proposed architecture for a new RAT based telecommunications system in which approaches in accordance with the principles described herein may be adopted, and the functionality disclosed herein may also be applied in respect of wireless telecommunications systems having different architectures.

[0041] Thus, certain embodiments of the disclosure as discussed herein may be implemented in wireless telecommunication systems / networks according to various different architectures, such as the example architecture shown in Figure 2. It will thus be appreciated the specific wireless telecommunications architecture in any given implementation is not of primary significance to the principles described herein. In this regard, certain embodiments of the disclosure may be described generally in the context of communications between network infrastructure equipment / access nodes and a communications device, wherein the specific nature of the network infrastructure equipment / access node and the communications device will depend on the network infrastructure for the implementation at hand. For example, in some scenarios the network infrastructure equipment / access node may comprise a base station, such as an LTE-type base station 1 which is adapted to provide functionality in accordance with the principles described herein, and in other examples the network infrastructure equipment may comprise a control unit / controlling node 40 and / or a TRP 10 of the kind shown in Figure 2 which is adapted to provide functionality in accordance with the principles described herein.

[0042] A more detailed diagram of some of the components of the network shown in Figure 2 is provided by Figure 3. In Figure 3, a TRP 10 as shown in Figure 2 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which may operate to control the transmitter 30 and the wireless receiver 32 to transmit and receive radio signals to one or more UEs 14 within a cell 12 formed by the TRP 10. As shown in Figure 3, an example UE 14 is shown to include a corresponding transmitter 49, a receiver 48 and a controller 44 which is configured to control the transmitter 49 and the receiver 48 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and to receive downlink data as signals transmitted by the transmitter 30 and received by the receiver 48 in accordance with the conventional operation.

[0043] The transmitters 30, 49 and the receivers 32, 48 (as well as other transmitters, receivers and transceivers described in relation to examples and embodiments of the present disclosure) may include radio frequency fdters and amplifiers as well as signal processing components and devices in order to transmit and receive radio signals in accordance for example with the 5G / NR standard. The controllers 34, 44 (as well as other controllers described in relation to examples and embodiments of the present disclosure) may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc., configured to carry out instructions which are stored on a computer readable medium, such as a non-volatile memory. The processing steps described herein may be carried out by, for example, a microprocessor in conjunction with a random access memory, operating according to instructions stored on a computer readable medium. The transmitters, the receivers and the controllers are schematically shown in Figure 3 as separate elements for ease of representation. However, it will be appreciated that the functionality of these elements can be provided in various different ways, for example using one or more suitably programmed programmable computer(s), or one or more suitably configured application-specific integrated circuit(s) / circuitry / chip(s) / chipset(s). As will be appreciated the infrastructure equipment / TRP / base station as well as the UE / communications device will in general comprise various other elements associated with its operating functionality.

[0044] As shown in Figure 3, the TRP 10 also includes a network interface 50 which connects to the DU 42 via a physical interface 16. The network interface 50 therefore provides a communication link for data and signalling traffic from the TRP 10 via the DU 42 and the CU 40 to the core network 20.

[0045] The interface 46 between the DU 42 and the CU 40 is known as the F 1 interface which can be a physical or a logical interface. The Fl interface 46 between CU and DU may operate in accordance with specifications 3GPP TS 38.470 and 3GPP TS 38.473, and may be formed from a fibre optic or other wired or wireless high bandwidth connection. In one example the connection 16 from the TRP 10 to the DU 42 is via fibre optic. The connection between a TRP 10 and the core network 20 can be generally referred to as a backhaul, which comprises the interface 16 from the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40.

[0046] Although reference is made to 5G networks, the discussions in this specification apply equally to 6G networks (and beyond) where there is expected to be significantly higher throughput, lower latency and higher reliability utilising sub-THz frequencies.

[0047] RF Incident Energy

[0048] As explained above with reference to the example shown in Figures 1A and IB, Ambient loT proposes to use energy received from a radio frequency carrier wave in order to power devices. An Ambient loT device could be powered by other ambient power sources, such as solar or thermal power. Harvesting energy based on the incident RF energy has several advantages and disadvantages.

[0049] An advantage is that the RF energy is always available. Therefore, the Ambient loT device can always be awake while being powered from this energy. Furthermore, a signal transmitted in the uplink from a tag can be backscattered using the incident radio frequency wave.

[0050] A disadvantage is that the received power of the RF energy source is typically low. A receiver operating on such energy typically requires a power level of -30dBm to -20dBm for operation, which is not consistent with the low amounts of received power that are typically available directly from a base station. This required received power level sets a limit on the range (communication distance) supported by the AIoT system.

[0051] Another disadvantage is that the transmission power level of a device that is powered by an RF energy source is typically very low. Such devices may operate based on backscattering technology, for example. The backscattered signal is created at the same carrier frequency as the incident RF energy. It is thus hard for the source of the RF energy (e.g., a gNB) to differentiate between the transmitted RF signal and the backscattered signal.

[0052] Another disadvantage is that, so as to reduce the power consumption of a receiver that operates on incident RF energy, a low power waveform / signalling scheme that is amenable to being decoded and received by a low power consumption receiver is typically required. For example, an on-off keying (OOK) signalling scheme may be used for such lower power communications. There are then issues of multiplexing this new signalling scheme with the currently supported orthogonal frequency-division multiplexing (OFDM) and Discrete Fourier Transform-Spread-OFDM (DFT-s-OFDM) waveforms.

[0053] Despite the above-listed disadvantages, it is considered that Ambient loT based on RF incident energy is feasible. Hence, 3GPP have started the study item on Ambient loT technology [1], which is revised in

[0054] [2], and have collected some initial design targets, requirements, topologies, deployment scenarios etc in

[0055] [3].

[0056] Backscattering Principle

[0057] A passive device can transmit in the uplink (UL) using the backscattering principle. The UL signal can be backscattered on RF incident energy that can be either ambient (some RF energy that is already being transmitted in the ether, such as a cellular radio signal or a TV signal) or transmitted as a carrier-wave by a CW emitter for the express purpose of being backscattered. In either case, backscattering is performed based on the backscattering principle which is further described below.

[0058] Different from the conventional wireless communications device which actively generates its own signal, backscattering devices rely on reflecting an incident signal to transmit data. The encoded data is modulated by varying the amplitude (ASK), phase (PSK), or frequency (FSK) of the backscattered signal. More specifically, backscattering modulation is achieved by alternating between distinct load impedances of the antenna, with each impedance state leading to a unique characteristic of the reflected signal [4] . Figure 4 illustrates a generic form of the backscattering circuitry including a matching network and an integrated circuit (IC).

[0059] There are two aspects of power that are relevant to the Ambient loT device:

[0060] • Absorbed power - this is the power that is energy harvested and can be used to drive the circuits within the tag; and

[0061] • Reflected power - this is the power that is reflected as a backscattered signal.

[0062] Given the antenna and load impedances denoted as Za= Ra+ j'Xaand Zn= Rn+ jXn, n = 1,2, respectively, the reflection coefficient corresponding to each state is expressed as: where * denotes the complex conjugate operation. It should be noted that Figure 4 shows the antenna impedance Zaas Zant. It should also be noted that it is possible for the load impedance to vary between more than two states, while in the present disclosure, binary state switching is considered for the sake of simplicity of explanation. Ideally, when the load impedance is set to the complex conjugate of the antenna impedance at a certain state, n = 1, Z, = Z„, = 0 holds and thus the received power is completely absorbed by the communications device, leading to a lower reflection state. Different reflection coefficients can be obtained with different values of load impedance. For example, a value of Znthat is much greater than Zawill lead to a reflection coefficient close to 1, leading to a higher reflection state. It should furthermore be noted that, in practice, the reflection coefficient |Fn| depends on the manufacturing process and may vary within the range of (0,1).

[0063] The absorbed power can be calculated as: where Pavan denotes the power delivered from the antenna when the load impedance perfectly matches with the antenna impedance. It should be noted that in the literature the expression: is defined as the power transmission coefficient [5], In fact, the power captured by the antenna will be split into two; one part is scattered back to the reader while another part is delivered to the tag. For the design of the reflection ratio, a trade-off needs to be considered to balance the need for both parts of the power.

[0064] Given Pavau, the average power absorbed by the device can be calculated as:

[0065] Pin = Pavail (Pl (l " 1 ^ |2) + p2(1 - |F2|2)) where pn;n=i,2 denotes the ratio of time duration for each impedance state; p = p2holds if the probability of each impedance equals to the other (this also means the same probability of 0s and Is appeared in the encoded data if the backscattered signal uses a pure OOK waveform). Assuming that there are no antenna losses, the backscattered signal power is calculated as (considering ideal antenna):

[0066] CW Emitter

[0067] The carrier-wave emitter (or CW emitter / CWE) transmits a carrier wave signal (CWS) that can be used by the tag to backscatter a signal from. The tag may additionally harvest energy from the CWS or simply use the power from the CWS to power the circuitry in the tag (i.e. energy may not be stored by the tag but may be used for ongoing operations).

[0068] Such a scenario is shown in Figure 5. Figure 5 shows a tag 1 with a backscattering module 60. The backscattered signal is backscattered on the CW signal by the backscattering circuit, which may have the structure shown in Figure 4. The tag 1 includes an energy harvesting module 62, which converts energy of the earner wave signal into power to drive a microcontroller 64 and the backscattenng module 60. The tag can be powered by non-RF energy sources, such as via solar power. The tag can also and / or alternatively be powered by an RF energy source. The RF energy source may be the same signal as the CW emitter (the CW signal may both power the tag and provide a signal that can be backscattered from).

[0069] The CW emitter devices may take the following forms:

[0070] • Base station - the base station (e.g. gNodeB) acts as the CW emitter;

[0071] • Intermediate node - a reader may act as the CW emitter. The reader is a device that receives the backscattered signal, demodulates it and sends the result to the base station. The reader may also send signals (R2D - reader to device) to the tag; or

[0072] • Dedicated node - the CW emitter may be a dedicated node whose purpose is to provide a CW signal that can be backscattered from. The CW signal can also be used to power the tag, as discussed above.

[0073] The tag may receive sufficient power to decode downlink signalling, but not have sufficient power to transmit a backscattered signal in the UL (there is insufficient link budget in the uplink). In an example, the tag can decode the AIoT downlink based on ambient RF power, for example power that is received directly from the gNB. It should be noted that the signals that are sent from a base station or reader to the tag are considered to be downlink signals from the perspective of the tag. These signals can be actually transmitted in uplink spectrum. Those skilled in the art would understand, with respect to the context of what is being described, when the term “downlink” refers to the topological direction of travel of a signal and when it refers to specific types of spectrum.

[0074] A CW emitter may be capable of transmitting different types of signal. For example, a CW emitter may be capable of transmitting a CW signal, as discussed above, which allows a tag to backscatter or harvest energy. Such a CW signal can be a single tone or multi-tone signal. In addition, a CW emitter may be able to transmit a reference signal. Such a reference signal may be a multi-tone signal, e.g. in the form of a reference signal used in LTE or NR networks. Examples include a sounding reference signal (SRS) or a demodulation reference signal (DMRS). However, the CW emitter may be able to transmit other types of reference signals.

[0075] The protocol for Ambient loT operation can be based on a command / response type of protocol. The detection station (which might be the gNodeB) sends a downlink command signal with a command to the tag. For example, the downlink command signal could indicate to the tag that it should respond with its identity (such as an identity number). The downlink command signal could indicate some further aspect of how the tag should respond. For example, the downlink command signal may indicate an amount of frequency shift that should be applied to the response signal, or may indicate a time at which the response signal should be transmitted. Based on the downlink command signal, the tag responds with a backscattered signal, where the backscattered signal is backscattered on the carrier wave signal.

[0076] Figure 6 shows an example of an A-IoT network. There are three CWEs illustrated in the example network shown in Figure 6; each CWE is scheduled by the gNB for the CW transmission to the A-IoT device (named as ‘Tag’ in Figure 6). The tag may also receive a command from the gNB and respond accordingly, e.g., standby, data transmission and reflection in a manner known by the gNB.

[0077] In a general indoor scenario, A-IoT devices (also called tags) are deployed and attached to objects for various purposes, e.g., inventory, environment monitoring, etc. Tags are connected to a cellular network which is served by a single gNB or reader. Since the tags can only conduct backscattering communications, a bi-static topology is shown in order to enhance the communication range; this is realized by the deployment of multiple carrier wave emitters (CWEs) which transmit CWSs to the tag and enable backscattering at the tag.

[0078] Capability of CWEs

[0079] CWEs can receive, process, and transmit OFDM-based multi-tone signals, for example control signals sent by a gNodeB or other controlling node. The CW that the CWEs transmit may be, for example, in the form of an unmodulated single-tone signal (however other types of tone may be used), which can be generated by only transmitting through a single OFDM subcarrier or other ways compatible to the OFDM based signal generation process.

[0080] Capability of Tags

[0081] Depending on whether the tag can actively generate the signal or not, the tags are categorized into either active tags or (semi-) passive tags. Passive tags rely on backscattering communications. Active devices can actively generate a signal and transmit the signal at a desired frequency.

[0082] Passive tags cannot actively generate signals for transmission due to their low-complexity nature. They don’t support decoding OFDM-based multi-tone signals. They can decode signals that are sent on a R2D (reader to device, where the gNB can act as the reader) link when the R2D link uses a simple modulation scheme, such as OOK or FSK. This decoding could be done with a simple low power receiver, such as an envelope detector. For the D2R (device to reader) link, different backscattering modulation schemes may be applied, such as on-off keying (OOK), frequency shift keying (FSK), phase shift keying (PSK) and other schemes, given the incident CW signal.

[0083] Apart from the basic functionalities, e.g., data transmission, registration, and identification, etc., the tag is also able to be controlled, based on the command received from gNB on the R2D link, via its controller to achieve a certain reflection state, such as a high reflection state or a low / no reflection state. It should be noted that the tag can exploit the difference between impedance states to yield various reflection ratios (as described above with reference to Figure 4); for example, constant absorption / reflection, etc. (i.e. high reflection and low / no reflection states can be achieved by changing the reflection ratios).

[0084] Depending on the availability of energy storage, tags may be categorized into passive (without energy storage) and semi-passive (with energy storage) devices. An energy harvester is usually implemented to extend the life of the device and its type may include RF -based and other types of energy sources.

[0085] The tags have low accuracy clocks in order to reduce device complexity and to reduce tag power consumption. The tag is hence unable to accurately synchronise to the reader (e.g. gNB) and is unable to maintain accurate and consistent timing between synchronisation events (e.g. transmission of the SSB) as the tag’s clock would drift in the meantime.

[0086] Topologies and Agreements for Ambient loT Device Design

[0087] Use cases, topologies and functionalities required for AIoT have been discussed in [3], For example, two possible topologies, named Topology 1 and Topology 2. have been discussed, as explained in more detail below.

[0088] Topology 1: Base Station (BS)-Ambient loT Device

[0089] An example of Topology 1 is shown in Figure 7A, which is a reproduction of Figure 4.2. 1.1-1 of [3], In Topology 1, an ambient loT device 74 directly and bi-directionally communicates with a base station 72. The communication between the base station 72 and the ambient loT device 74 includes AIoT data and / or signalling. Although not shown in Figure 7A, Topology 1 includes the possibility that the base station transmitting to the AIoT device is a different from the base station receiving from the AIoT device.

[0090] Topology 2: Intermediate Node - Ambient loT device

[0091] An example of Topology 2 is shown in Figure 7B, which is a reproduction of Figure 4.2.1. 1-2 of [3] . In Topology 2, the Ambient loT device 74 communicates bi-directionally with an intermediate node 76 between the AIoT device 74 and the base station 72. In Topology 2, the intermediate node 76 may be a relay, IAB node, UE, repeater, etc. which is capable of performing AIoT techniques. The intermediate node 76 transfers AIoT data and / or signalling between base station 72 and the AIoT device 74.

[0092] For further detail relating to AIoT, reference may be made to any of the cited documents [1] to [5], the contents of which are hereby incorporated by reference.

[0093] Technical Issue

[0094] In [2], 3GPP RAN2 agreed that A-IoT devices can receive a paging-like triggering message from a reader / network. If a UE ID is included in the paging-like triggering message, the UE initiates a random access procedure to engage data reception and / or transmission from the network. In addition, RAN2 agreed that slotted-ALOHA-based access was to be studied for A-IoT devices.

[0095] One example for slotted-ALOHA-based access is captured in [6] . This example is shown by the message flow diagram of Figure 8, which is also aligned with Radio Frequency Identification (RFID). With reference to Figure 8, an access occasion (such as occasions 81 and 82) are opportunities which are supposed to be used by one device to access the network, while an access round (such as rounds 83 and 84) are rounds comprising multiple access occasions and therefore allow multiple devices to access the network. The text from [6], which explains the steps of the example message flow diagram of Figure 8, is reproduced below for ease of understanding:

[0096] Step 0. The initial message (e.g., paging-like message) is sent from BS-reader to device. The paging-like message can indicate which device(s) needs to respond, e.g., through indication information (e.g., mask / filter information). Once matching the indication information, the device starts to monitor possible Access Round Indication message.

[0097] Step 1: BS-reader sends Access Round Indication message which includes access configuration information (i.e., the number of access occasions 81, 82 in this round 83) to devices.

[0098] Step 2: Once receiving the Access Round Indication message, the device randomly selects an access occasion 81 according to the access configuration information (i.e., the total number of access occasions 81, 82), and loads this value into the access occasion counter. Then the device begins to wait for its own access occasion 81 to send Random Access ID message. Since A-IoT devices cannot maintain the accurate timing, the devices decide the access occasion according to the number of received (Next) Access Occasion Indication messages.

[0099] • If a device picks zero as its access occasion index, it replies a Random Access ID message immediately, which includes a random number; or

[0100] • If a device picks non-zero as its access occasion index, it decrements the access occasion counter every time it receives a (Next) Access Occasion Indication message. The device replies a Random Access ID message when its access occasion counter reaches zero. Step 3 : If a BS-reader successfully receives one Random Access ID, it replies with the Access ID Response message. The Access ID response includes the random number same as what the device has transmitted in Random Access ID, in order to indicate which device successfully performed contention resolution.

[0101] Step 4: The device considers that the contention resolution is successful, if the received Access ID Response contains the same random number used previously in the Random Access ID. Then the device sends UL data to the BS-reader. For example, in the inventory cases, the UL data includes the device ID.

[0102] Step 5 : Optionally, the device can perform subsequent UL / DL data transmissions for command services after Step 4.

[0103] Steps 6-7 : The BS-reader can continue to send (Next) Access Occasion Indication to trigger the other device(s) selecting the next occasion 82 to access. Then the other device(s) performs the same procedures as in Steps 3-6.

[0104] Step 8: The BS-reader can also send another Access Round Indication message to trigger the next round 84 of access occasion(s) for devices that failed to perform contention resolution.

[0105] It should be noted that access round structure described in Figure 8 is just an example of communication and synchronization timing between the network and the device. Hence, those skilled in the art would appreciate that any other suitable periodic or aperiodic frame structure may be employed, depending on the outcome of the study item.

[0106] For A-IoT, a device may not have a connection with a specific cell / reader, and so there is no tracking area update and no cell selection / reselection. The device usually responds to a paging-like triggering message whenever it receives one from any reader. There is an issue here, in that if the device is close to two or more readers, and so the device may receive paging-like triggering messages from at least two of these readers i.e., one after the other.

[0107] For example, and as illustrated by the example of Figure 9, if the triggering message contains “inventory” to count the number devices present in the warehouse where multiple readers are installed in the area, an AIoT device 93 may receive a triggering message from a first reader 91 and respond accordingly, and then may also receive another triggering message in the same access round period from a second reader 92. It may therefore be necessary to define if and how the device 93 should respond or not accordingly to these triggering messages from readers 91 and 92. The issue is that responding involves transmission and reception with the readers 91, 92, including contention-based access procedure as explained above, which will heavily impact the power consumption of the device 93 as well network load and signalling overhead.

[0108] In addition, if it is assumed that the core network (CN) initiates the paging message via the base station / gNB / reader for a device or a group of devices, it is likely that paging messages may be sent to multiple close-by readers as the CN does not know the exact location of a specific device. It should be noted here that there are cases where device IDs may not be included, for example for the case of “Inventory” (as noted above in respect of the description of step 4 of Figure 8) which is intended for all devices. Hence, a technical problem to solve is how to define the behaviour and / or actions of an AIoT device when the device receives more than one triggering message in the same access round period from different readers, or even after one or more access round periods. It should be noted that it is assumed herein that the paging-like triggering messages which are transmitted to the A-IoT devices carry the configuration of the frame timing, known as “access round', where each access round comprises a variable number of engaging periods as shown in the example of Figure 8. One difference is that instead of using the term “access occasion ” , reference is made herein instead to the term “engaging period” to avoid any confusion in respect of the similar terminology of “occasion” used by legacy LTE and NR. This would in any case be clear to those skilled in the art in respect of the context of the invention as defined herein.

[0109] AIoT Device Behaviour for Responding to Multiple Paging Messages from Different Readers

[0110] Figure 10 shows a part schematic, part message flow diagram representation of a wireless communications system comprising a communications device 101 (e.g., a tag 1) and a plurality of readers 102, 103 in accordance with at least some embodiments of the present technique. Here, the communications device 101 (e.g., tag 1) is an AIoT-type device, which may comprise receiver circuitry 101.1, to receive downlink signals (e.g. from the readers 102, 103 or base stations of the wireless communications system). The communications device 101 may comprise transmitter circuitry as well as the receiver circuitry for transmitting uplink signals (e.g. to the readers 102, 103 or base stations of the wireless communications system), or may comprise transceiver circuitry instead of the receiver circuitry 101.1 2which capable of both receiving downlink signals and transmitting uplink signals. The communications device 101 may further comprise energy harvesting circuitry 101.2, configured to harvest energy from one or more ambient sources, such as incident carrier wave signals (which may be transmitted by carrier wave emitters not shown in the example of Figure 10). Other examples of such ambient sources includes solar / light, piezoelectric (i.e. kinetic / vibration), electromagnetic, electrostatic, heat / thermal, thermoelectric, magnetic, wind / water, acoustic, etc. The communications device 101 in at least some arrangements of embodiments of the present technique (such as those where it does not comprise a transmitter or means to transmit uplink signals in the manner of non-AIoT devices) may also comprise backscattering circuitry 101.3 configured to backscatter incident carrier wave signals (e.g. from carrier wave emitters not shown in the example of Figure 10) for receipt by the readers 102, 103.

[0111] Here, the readers may be either implemented within base stations (e.g., the gNB 4 of Figure 1A) or implemented as detection stations (e.g., within the UE 7 of Figure IB) separate from the base stations, and configured to forward signals received via detected backscattered signals or as transmitted uplink signals from the communications devices / tags in range to the base stations. The readers 102, 103 may each comprise transceiver circuitry 102.1, 103.1 configured to transmit signals to and / or to receive backscattered signals from the communications device 101.

[0112] The communications device 101 and the readers 102, 103 may each comprise a controller (or controller circuitry) 101.4, 102.2, 103.2. Each of the controllers 101.4, 102.2, 103.2 may be, for example, a microprocessor, a CPU, or a dedicated chipset, etc.

[0113] As shown in the example of Figure 10, the controller 101.4 of the communications device 101 is configured in combination with the receiver (or transceiver) circuitry 101.1 (and, in some arrangements, the backscattering circuitry 101.3) of the communications device 101 to receive 104, from the first reader 102 during a first access round period, a first triggering message to trigger an access procedure between the communications device 101 and the first reader 102, to receive 105, from the second reader 103 during the first access round period, a second triggering message to trigger an access procedure between the communications device 101 and the second reader 103, and to respond (e.g. by generating and transmiting signals internally by the transmiter / transceiver circuitry or backscatering incident carrier waves signals by the backscatering circuitry 101.3) either to only 106 the first triggering message or to both 106, 107 of the first triggering message and the second triggering message in accordance with a triggering message response rule.

[0114] Essentially then, some embodiments of the present technique, as exemplified by the example wireless communications system of Figure 10, propose that when an AIoT device receives more than one paging / triggering message (i.e. to trigger it to perform an access procedure, such as a random access (RACH) or initial access procedure with the network) from different readers in a single access round period, the AIoT device responds to one or more of those triggering messages in accordance with a particular rule or rules.

[0115] In effect, in accordance with at least some arrangements of embodiments of the present technique, when the AIoT device receives more than one paging / triggering message from different readers in a single access round period, the AIoT device performs the actions / behaviour in accordance with at least one of the following options:

[0116] Option 1: The AIoT device is not allowed to respond to triggering messages from different readers within a single access round period. That is, the device ignores (and doesn’t respond to) triggering messages from different readers to the current reader (i.e., the reader to which it did respond to and is thus accessing) within the current access round period. In other words, in respect of option 1, the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period;

[0117] Option 2: The AIoT device is allowed to respond triggering messages from different readers within an access round period. That is, the device engages to respond to at least one triggering message within an access round period from a different reader. In other words, in respect of option 2, the triggering message response rule defines that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period;

[0118] Option 3 : The AIoT device is only allowed to respond to other triggering messages from different readers after multiple access round periods have been completed with the current reader (i.e., device is locked to the current reader for a particular set of access round periods or for a set time). In other words, in respect of option 3, the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during one or more subsequent access round periods after the first access round period; and

[0119] Option 4: The AIoT device receives a configuration from the current reader / network that defines whether the device is allowed to respond to other paging messages from different readers within one or more access round periods. In other words, in respect of option 4, the first triggering message comprises an indication of the triggering message response rule.

[0120] It should be noted that, in accordance with at least some arrangements of embodiments of the present technique, the AIoT device may operate in accordance with a combination of more than one of the abovedescribed options.

[0121] In respect of option 1 above, if the device received a paging message with no device ID from the current reader, that for example is addressed to all devices and where there is only one service supported by A- loT devices, then another paging message from a different reader is unlikely to trigger the same service. So, there is no need for the device to respond to more than one triggering message in the same access round period from a different reader.

[0122] If the device received paging with its ID being present from the current reader, and received another paging with the same ID from a different reader and the rest of the parameters in the paging message are the same, then UE does not respond to the second paging message within an access round period. When other parameters are different in the paging messages (e.g., paging ID), such scenarios are explained in further detail below (i.e., when different paging IDs indicate different readers).

[0123] As shown in the example of Figure 11, there are two access rounds: an access round 1 and access round 2 where each access round comprises a number of engaging periods for different devices. The engaging period is where the device gets its opportunity for random access, DL receptions, and UL transmissions. For example, using slotted-ALOHA based access (i.e., based on time division multiple access (TDMA)), device 1 occupies engaging period 7, and device 2 will occupy engaging period 2, both with the same reader 1.

[0124] After device 1 has completed its engaging period 7, if it has again received another paging message from reader 2 before access round period 1 is completed from reader 7, then device 1 will take an action in accordance with option 1 described above that it is not allowed to respond to this paging message, because it is unlikely that the same service will be triggered for the same device in that short period.

[0125] In some arrangements of embodiments of the present technique, devices may be allowed to respond to another paging message from another reader after the current access round period is completed, based on the timing / signalling from the network / reader (e.g., in a triggering message received from that (current) reader). In other words, the triggering message response rule may further define that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader if the one or more further triggering messages are each received during a different access round period to the first access round period.

[0126] In contrary to option 1, in respect of option 2 above, an AIoT device is allowed to respond to another paging message within the current access round period from a different reader. This is because the device may have moved on to another location, or the channel condition for the latest / current reader may become bad, and / or channel condition of another reader may reach a more acceptable level. Hence, based on this argument, there may be a need for the device to respond to another triggering message within an access round period. This may be conditional on the latest reader not being available anymore, due to mobility or channel condition reasons as described above. In other words, the triggering message response rule may further define that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period if it is no longer possible for the communications device to receive signals from the first reader (e.g. after receiving the first triggering message but before responding to the first triggering message, or after responding to the first triggering message but being unable to continue the random access procedure or data exchange).

[0127] As noted above, in the example of Figure 11, there are two access rounds: an access round 1 and an access round 2. where each access round comprises a number of engaging periods for different devices. For example, device 1 occupies engaging period 7, and device 2 will occupy engaging period 2, both with the same reader 1. After device 1 has completed its engaging period 7, if it has again received another paging message from reader 2 before access round period 1 is completed from reader 7, then device 1 can respond to this paging message from reader 2 provided that the latest reader 1 is not available anymore. In such arrangements of embodiments of the present disclosure, it is assumed that the device’s location is tracked, and it is important for the network to know the device’s location at the granularity of a reader level at least, so as to determine whether the device is unable to communicate with the current reader (e.g. based on mobility or changing channel conditions) because it may be not be possible for such a low power AIoT device to perform measurements and make such a determination itself.

[0128] In respect of option 3 above, the AIoT device is allowed to respond to other paging messages from different readers after multiple access round periods (i.e., a fixed number of access rounds) are completed, where the end timing of these access rounds is based on the indication / signalling from the network / reader (e.g., in a triggering message). This means that the device is only allowed to respond to a paging message from the current reader within one or more access round periods as long as the current reader is available. For example, the first triggering / paging message indicates the current reader ID and device ID, and indicates that the communication can only take place between them until the device is given permission to respond to other triggering messages from other readers nearby, after the fixed number of access rounds have passed, for example. That is, in other words, the triggering message response rule may further define that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader during one or more further access round periods after the one or more subsequent access round periods.

[0129] In some deployments, such as in a warehouse, there may be only one reader in a particular part of the warehouse, like a reader placed at the entry gate, where this reader performs inventory checks - i.e., monitors what comes in and what goes out (this is termed as gate-in inventory and gate-out inventory). In that period, where the inventory task is ongoing, all devices in the vicinity of the reader can be locked to communicate only with this single reader, and when inventory is completed (e.g., after the fixed number of access periods), the devices are unlocked.

[0130] In some arrangements of embodiments of the present technique, a device may only be allowed to receive a paging message from the current reader for a period of time, where this period of time is indicated by the current reader / network (e.g., in a triggering message). In other words, the triggering message response rule may further define that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during a period of time indicated by the first triggering message.

[0131] In respect of option 4 above, the network / reader configures (e.g., in a triggering message) whether a device is allowed to respond to other paging messages from different readers within one or more access round periods where the end timing of these access rounds is based on the indication / signalling from the network / reader (e.g., in the triggering message). In other examples however, the rule may be fixed in the specifications and / or define a set of implicit actions to be performed by the AIoT device based on its implementation. In other words, the triggering message response rule may be preconfigured and known to the communications device.

[0132] It should be noted that the above options are considered with and without including an indication of a paging ID in the triggering messages, but the reader ID is assumed to be always included in the triggering messages. It should also be noted that all options described above (i.e., options 1 - 4), the device’s behaviour can be specified by explicit signalling / configuration from the reader / network or by implicit device behavior where actions are based on the device implementation. In other words, paging message or similar may indicate if UE is allowed to respond to multiple paging messages during an access period or if response is locked to a particular reader.

[0133] If an indication of the paging ID is included in the triggering message, it can indicate that the triggering message is coming from a different reader (if the ID is different from the one received from the current reader). In this case, the paging ID could indicate different readers and it will allow devices to determine the originator reader ID. For example, if device received a paging message with first a paging / reader ID and a subsequent paging message with second paging / reader ID, then the device can know that these two paging messages originated from two different readers and is able to take appropriate action as described in respect of the above options. In other words, the first triggering message may comprise a first identifier associated with the first reader and wherein the second triggering message may comprise a second identifier associated with the second reader.

[0134] Another use case where paging ID is needed in paging messages is if more than one company / network operator shares a particular area (such as a warehouse) and they page their respective UEs for inventory and other command; effectively allowing the sharing of an AIoT system and / or tags between two companies. In this case, the paging ID indicates the network identity. Devices will receive a configuration in the paging-like triggering messages with a mapping of device ID and paging / network ID. In other words, the first triggering message may comprise an identifier associated with a wireless communications network of which the first reader forms part and wherein the second triggering message may comprise an identifier associated with a wireless communications network of which the second reader forms part (this may be the same or a different network to that of which the first reader forms part).

[0135] Figure 12 shows a flow diagram illustrating an example process of communications in a communications system in accordance with embodiments of the present technique. The process shown by Figure 12 is specifically a method of operating a communications device (e.g., a tag) configured to harvest energy from ambient sources and to communicate with one or more readers of a communications system.

[0136] The method begins in step SI. The method comprises, in step S2, receiving, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader. In step S3, the process comprises receiving, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader. In step S4, the method then comprises responding either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule. The process ends in step S5.

[0137] Those skilled in the art would appreciate that the method shown by Figure 12 may be adapted in accordance with embodiments of the present technique. For example, other intermediate steps may be included in such a method, or the steps may be performed in any logical order. Though embodiments of the present technique have been described largely by way of the example communications system shown in Figure 10, it would be clear to those skilled in the art that they could be equally applied to other systems to those described herein, provided that these are within the scope of the claims.

[0138] Those skilled in the art would further appreciate that such infrastructure equipment and / or communications devices as herein defined may be further defined in accordance with the various arrangements and embodiments discussed in the preceding paragraphs. It would be further appreciated by those skilled in the art that such infrastructure equipment and communications devices as herein defined and described may form part of communications systems other than those defined by the present disclosure, provided that these are within the scope of the claims.

[0139] The following numbered paragraphs provide further example aspects and features of the present technique:

[0140] Paragraph 1. A method of operating a communications device configured to harvest energy from one or more ambient sources and to communicate with one or more readers of a communications system, the method comprising receiving, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, receiving, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and responding either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

[0141] Paragraph 2. A method according to Paragraph 1, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period.

[0142] Paragraph 3. A method according to Paragraph 2, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader if the one or more further triggering messages are each received during a different access round period to the first access round period.

[0143] Paragraph 4. A method according to any of Paragraphs 1 to 3, wherein the triggering message response rule defines that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period.

[0144] Paragraph 5. A method according to Paragraph 4, wherein the triggering message response rule further defines that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period if it is no longer possible for the communications device to receive signals from the first reader. Paragraph 6. A method according to any of Paragraphs 1 to 5, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during one or more subsequent access round periods after the first access round period.

[0145] Paragraph 7. A method according to Paragraph 6, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader during one or more further access round periods after the one or more subsequent access round periods.

[0146] Paragraph 8. A method according to any of Paragraphs 1 to 7, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during a period of time indicated by the first triggering message. Paragraph 9. A method according to any of Paragraphs 1 to 8, wherein the first triggering message comprises an indication of the triggering message response rule.

[0147] Paragraph 10. A method according to any of Paragraphs 1 to 9, wherein the triggering message response rule is preconfigured and known to the communications device.

[0148] Paragraph 11. A method according to any of Paragraphs 1 to 10, wherein the first triggering message comprises a first identifier associated with the first reader and wherein the second triggering message comprises a second identifier associated with the second reader. Paragraph 12. A method according to any of Paragraphs 1 to 11, wherein the first triggering message comprises an identifier associated with a wireless communications network of which the first reader forms part, and wherein the second triggering message comprises an identifier associated with a wireless communications network of which the second reader forms part.

[0149] Paragraph 13. A communications device comprising receiver circuitry to receive downlink signals, energy harvesting circuitry configured to harvest energy from one or more ambient sources, and controller circuitry configured in combination with the receiver circuitry and the backscattering circuitry to receive, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, to receive, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and to respond either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

[0150] Paragraph 14. Circuitry for a communications device, the circuitry comprising receiver circuitry to receive downlink signals, energy harvesting circuitry configured to harvest energy from one or more ambient sources, and controller circuitry configured in combination with the receiver circuitry and the backscattering circuitry to receive, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, to receive, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and to respond either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

[0151] Paragraph 15. A method of operating a first reader forming part of a wireless communications network and configured to transmit signals to and / or to receive backscattered signals from a communications device, the method comprising transmitting, to the communications device during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, and receiving, from the communications device during the first access round period, a response to the first triggering message in accordance with a triggering message response rule.

[0152] Paragraph 16. A method according to Paragraph 15, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period.

[0153] Paragraph 17. A method according to Paragraph 16, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader if the one or more further triggering messages are each received by the communications device during a different access round period to the first access round period.

[0154] Paragraph 18. A method according to any of Paragraphs 15 to 17, wherein the triggering message response rule defines that the communications device is allowed to respond to both of the first triggering message from the first reader and a second triggering message received by the communications device from a second reader during the first access round period.

[0155] Paragraph 19. A method according to Paragraph 18, wherein the triggering message response rule further defines that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period if it is no longer possible for the first reader to transmit signals to the communications device.

[0156] Paragraph 20. A method according to any of Paragraphs 15 to 19, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during one or more subsequent access round periods after the first access round period.

[0157] Paragraph 21. A method according to Paragraph 20, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader during one or more further access round periods after the one or more subsequent access round periods.

[0158] Paragraph 22. A method according to any of Paragraphs 15 to 21, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during a period of time indicated by the first triggering message.

[0159] Paragraph 23. A method according to any of Paragraphs 15 to 22, wherein the first triggering message comprises an indication of the triggering message response rule.

[0160] Paragraph 24. A method according to any of Paragraphs 15 to 23, wherein the triggering message response rule is preconfigured and known to the communications device.

[0161] Paragraph 25. A method according to any of Paragraphs 15 to 23, wherein the first triggering message comprises a first identifier associated with the first reader.

[0162] Paragraph 26. A method according to any of Paragraphs 15 to 24, wherein the first triggering message comprises an identifier associated with the wireless communications network of which the first reader forms part.

[0163] Paragraph 27. A method according to any of Paragraphs 15 to 25, wherein the reader is implemented within a base station of the wireless communications network.

[0164] Paragraph 28. A method according to any of Paragraphs 15 to 25, wherein the reader is implemented within a detector station and is configured to detect signals from the communications device and forward the detected signals to a base station of the wireless communications network.

[0165] Paragraph 29. A reader forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, and to receive, from the communications device during the first access round period, a response to the first triggering message in accordance with a triggering message response rule.

[0166] Paragraph 30. Circuitry for a reader forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, and to receive, from the communications device during the first access round period, a response to the first triggering message in accordance with a triggering message response rule.

[0167] Paragraph 31. A wireless communications system comprising a communications device according to Paragraph 13 and a reader according to Paragraph 29.

[0168] Paragraph 32. A wireless communications system according to Paragraph 31, further comprising a carrier wave emitter station configured to transmit the carrier wave signals.

[0169] Paragraph 33. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to any of Paragraphs 1 to 12 or Paragraphs 15 to 28.

[0170] Paragraph 34. A non-transitory computer-readable storage medium storing a computer program according to Paragraph 33.

[0171] It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and / or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and / or processors may be used without detracting from the embodiments.

[0172] Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more data processors and / or digital signal processors. The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and / or processors.

[0173] Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognise that various features of the described embodiments may be combined in any manner suitable to implement the technique.

[0174] References

[0175] [1] RP -234058, “New SID: Study on solutions for Ambient loT (Internet of Things) in NR”, Huawei, 3GPP TSG RAN Meeting #102, Edinburgh, December 2023.

[0176] [2] RP -240826, “Revised SID: Study on solutions for Ambient loT (Internet of Things) in NR”, CMCC, Huawei, T-Mobile USA, 3GPP TSG RAN Meeting #103, Maastricht, March 2024.

[0177] [3] TR 38.848, “Study on Ambient loT (Internet of Things) in RAN (Version 18.0.0)”, 3GPP, September 2023.

[0178] [4] “Sensing, Computing, and Communication for Energy Harvesting loTs: A Survey”, Dong Ma, Guohao Lan, Mahbub Hassan, Wen Hu, Sajal K. Das, [online, available at: https: / / arxiv.org / abs / 1905.03949], December 2019.

[0179] [5] “Ambient Backscatter Communications: A Contemporary Survey”, Van Huynh, Nguyen, Dinh Thai Hoang, Xiao Lu, Dusit Niyato, Ping Wang, and Dong In Kim, IEEE Communications Surveys & Tutorials 20, no. 4 (2018): 2889-2922.

[0180] [6] R2-2403114, “Random access-like procedure for Ambient loT”, Huawei, HiSilicon, 3GPP TSG RAN WG2 Meeting #125bis, Changsha, April 2024.

Claims

CLAIMSWhat is claimed is:

1. A method of operating a communications device configured to harvest energy from one or more ambient sources and to communicate with one or more readers of a communications system, the method comprising receiving, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, receiving, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and responding either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

2. A method according to Claim 1, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period.

3. A method according to Claim 2, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader if the one or more further triggering messages are each received during a different access round period to the first access round period.

4. A method according to Claim 1, wherein the triggering message response rule defines that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period.

5. A method according to Claim 4, wherein the triggering message response rule further defines that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period if it is no longer possible for the communications device to receive signals from the first reader.

6. A method according to Claim 1, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during one or more subsequent access round periods after the first access round period.

7. A method according to Claim 6, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader during one or more further access round periods after the one or more subsequent access round periods.

8. A method according to Claim 1, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during a period of time indicated by the first triggering message.

9. A method according to Claim 1, wherein the first triggering message comprises an indication of the triggering message response rule.

10. A method according to Claim 1, wherein the triggering message response rule is preconfigured and known to the communications device.

11. A method according to Claim 1, wherein the first triggering message comprises a first identifier associated with the first reader and wherein the second triggering message comprises a second identifier associated with the second reader.

12. A method according to Claim 1, wherein the first triggering message comprises an identifier associated with a wireless communications network of which the first reader forms part, and wherein the second triggering message comprises an identifier associated with a wireless communications network of which the second reader forms part.

13. A communications device comprising receiver circuitry to receive downlink signals, energy harvesting circuitry configured to harvest energy from one or more ambient sources, and controller circuitry configured in combination with the receiver circuitry and the backscattering circuitry to receive, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, to receive, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and to respond either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

14. Circuitry for a communications device, the circuitry comprising receiver circuitry to receive downlink signals, energy harvesting circuitry configured to harvest energy from one or more ambient sources, and controller circuitry configured in combination with the receiver circuitry and the backscattering circuitry to receive, from a first reader during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, to receive, from a second reader during the first access round period, a second triggering message to trigger an access procedure between the communications device and the second reader, and to respond either to only the first triggering message or to both of the first triggering message and the second triggering message in accordance with a triggering message response rule.

15. A method of operating a first reader forming part of a wireless communications network and configured to transmit signals to and / or to receive backscattered signals from a communications device, the method comprising transmitting, to the communications device during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, and receiving, from the communications device during the first access round period, a response to the first triggering message in accordance with a triggering message response rule.

16. A method according to Claim 15, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period.

17. A method according to Claim 16, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader if the one or more further triggering messages are each received by the communications device during a different access round period to the first access round period.

18. A method according to Claim 15, wherein the triggering message response rule defines that the communications device is allowed to respond to both of the first triggering message from the first reader and a second triggering message received by the communications device from a second reader during the first access round period.

19. A method according to Claim 18, wherein the triggering message response rule further defines that the communications device is allowed to respond to both of the first triggering message from the first reader and the second triggering message from the second reader during the first access round period if it is no longer possible for the first reader to transmit signals to the communications device.

20. A method according to Claim 15, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during one or more subsequent access round periods after the first access round period.

21. A method according to Claim 20, wherein the triggering message response rule further defines that the communications device is allowed to respond to one or more further triggering messages from one or more different readers to the first reader during one or more further access round periods after the one or more subsequent access round periods.

22. A method according to Claim 15, wherein the triggering message response rule defines that the communications device is only allowed to respond to the first triggering message from the first reader during the first access round period, and wherein the triggering message response rule further defines that the communications device is only allowed to respond to one or more subsequent triggering messages from the first reader during a period of time indicated by the first triggering message.

23. A method according to Claim 15, wherein the first triggering message comprises an indication of the triggering message response rule.

24. A method according to Claim 15, wherein the triggering message response rule is preconfigured and known to the communications device.

25. A method according to Claim 15, wherein the first triggering message comprises a first identifier associated with the first reader.

26. A method according to Claim 15, wherein the first triggering message comprises an identifier associated with the wireless communications network of which the first reader forms part.

27. A method according to Claim 15, wherein the reader is implemented within a base station of the wireless communications network.

28. A method according to Claim 15, wherein the reader is implemented within a detector station and is configured to detect signals from the communications device and forward the detected signals to a base station of the wireless communications network.

29. A reader forming part of a wireless communications network, the infrastructure equipment comprising transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, and to receive, from the communications device during the first access round period, a response to the first triggering message in accordance with a triggering message response rule.

30. Circuitry for a reader forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to transmit signals to and / or to receive signals from a communications device, and controller circuitry configured in combination with the transceiver circuitry to transmit, to the communications device during a first access round period, a first triggering message to trigger an access procedure between the communications device and the first reader, and to receive, from the communications device during the first access round period, a response to the first triggering message in accordance with a triggering message response rule.

31. A wireless communications system comprising a communications device according to Claim 13 and a reader according to Claim 29.

32. A wireless communications system according to Claim 31, further comprising a carrier wave emitter station configured to transmit the carrier wave signals.

33. A computer program comprising instructions which, when loaded onto a computer, cause the computer to perform a method according to Claim 1 or Claim 15.

34. A non-transitory computer-readable storage medium storing a computer program according to Claim 33.

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