Methods, communications apparatus and devices

Abstract

A method of operating a reader device forming part of a wireless communications network and configured to transmit signals to and / or to receive signals from one or more low power AIoT devices via a ra

Description

BACKGROUND Field of the Disclosure The present disclosure relates to methods, a communications apparatus and devices. Background The “background” description provided 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 the 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 disclosure. Current and future wireless communications networks are expected routinely and efficiently to support communications with an ever-increasing range of devices associated with a wider range of data traffic profiles and types. For example, wireless communications networks will be expected efficiently to 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, devices 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 devices 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). 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, efficiently to support connectivity for a wide range of devices associated with different applications and different characteristic data traffic profiles and requirements. 5G NR has continuously evolved and the current work plan includes 5G-NR-Advanced in which some further enhancements are expected, especially to support new use-cases / scenarios with higher requirements. A further area of study which has developed concerns the use of low complexity devices, which may use power from incident radiation for communicating or backscattering received signals. Such devices may be referred to as tags or Ambient loT devices (tags / A-IoT). Improving communication with such devices can represent a technical challenge. SUMMARY The present disclosure can help address or mitigate at least some of the issues discussed above. According to example embodiments a communications device acting as a reader for a low power or ultra low power device, such as an A-IoT device, and a method of operating a reader device for a lower power device or an ultra low power device is disclosed. The reader forms part of a wireless communications network and is configured to transmit signals to and / or to receive signals from one or more other low power devices via a radio access interface between the reader device and the one or more other low power devices. The method comprises transmitting, to the one or more low power devices, a parameter as a schedule command to schedule physical resources for reader-to-device (R2D) or device-to-reader (D2R) data transmission, the parameter comprising information for mapping the physical resources; and performing data transmission with a first low power devices using the scheduled physical resources. According to various disclosed examples, the method can provide an energy efficient contention free channel access signaling method for A-IoT devices to access the channel resources. Respective aspects and features of the present disclosure are defined in the appended claims. 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. BRIEF DESCRIPTION OF THE DRAWINGS Non-limiting embodiments and advantages of the present disclosure are explained with reference to the following detailed description taken in conjunction with the accompanying drawings, in which like parts have the same numerical designations and wherein: Figures 1A and IB schematically represent examples of communications systems in which A-IoT devices 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; Figures 2A and 2B schematically represent examples in which a reader in the form of a base station of a wireless communications network (Figure 2A) and a communications device (UE) of a wireless communications network (Figure 2B) transmit a reader to device (R2D) signal to a A-IoT device and receive a response signal as a backscattered signal according to example embodiments; Figure 3 is a schematic block diagram illustrating an example wireless communications network configured in accordance with a 5G or new radio (NR) 3GPP standard according to example embodiments; Figure 4 is a schematic block diagram illustrating in more detail a communications device (e.g. a UE) and an infrastructure equipment (e.g. a gNB) formed from components of the wireless communications network shown in Figure 2; Figure 5 is a schematic block diagram illustrating an example of backscattering circuitry of an example A-IoT device; Figure 6 is a schematic illustration representing an example in which a carrier wave signal transmitted by an external carrier wave emitter is backscattered; Figure 7 schematically represent an example of communications systems in which A-IoT devices are deployed within partially overlapping coverage areas of two reader devices; Figure 8 is an illustrative representation of an example of TDMA based scheduling for a communications system comprising A-IoT devices and reader devices in accordance with embodiments of the present disclosure; Figure 9 is an illustrative representation of another example of TDMA based scheduling for a communications system comprising A-IoT devices and reader devices in accordance with embodiments of the present disclosure; Figure 10 is an illustrative representation of an example of combining FDMA and TDMA based scheduling for a communications system comprising A-IoT devices and reader devices in accordance with embodiments of the present disclosure; Figure 11 is an illustrative representation of an example scheduling life cycle for a communications system comprising A-IoT devices and reader devices in accordance with embodiments of the present disclosure; Figure 12 illustrates a signal flow diagram representation of an example communications system comprising A-IoT devices, reader devices and an infrastructure equipment in accordance with embodiments of the present disclosure; Figure 13 illustrates another signal flow diagram representation of an example communications system comprising A-IoT devices, reader devices and an infrastructure equipment in accordance with embodiments of the present disclosure; Figure 14 is a flow diagram illustrating a method of operating a reader device forming part of a wireless communications network and configured to transmit signals to and / or to receive signals from A-IoT devices in accordance with example embodiments of the present disclosure; and Figure 15 is a flow diagram illustrating a method of operating an A-IoT device configured to transmit signals to and / or to receive signals from reader devices forming part of a wireless communications network in accordance with example embodiments of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS Ambient loT In release 19 of 3GPP (Rei-19), 3GPP will study Ambient loT [1] where a communications device (such as a user equipment (UE)) is essentially a communications device with very limited energy consumption in range of 1 pW to several hundreds of pW. In Ambient loT, it is considered that the communications device may harvest energy to power its communication with a base station (such as a gNB). For example, the energy may be harvested from solar or kinetic energy such as vibrations. Alternatively, the energy to power the communications device may 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 communications 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, which can be referred to as “tags” because of the simplicity of the devices. These tags 1 are powered as a result of radio frequency energy received from an incident CW 2 transmitted by the CWE 3. The tags 1 may also be referred to as ambient loT (A-IoT) devices. In the present disclosure, the terms ‘tag’ and ‘ A-IoT device may be used interchangeably except where indicated otherwise. 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. In a second example, a UE 7 receives a backscattered signal 5 from the tags 1 or an RF signal generated by the tags 1. The UE 7 then transmits an indication of the received 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 received signals are detected by the detection station (UE) 7, and the detection station transmits an indication of the detected signals to the gNB 4. The station which controls the CWEs 3 may be regarded as a controller station. The station which detects the received signals 5 may be regarded as detection station. The detection station may also be referred to as reader. Therefore, in the Figure 1A both the controller station and the detection station are formed by a gNB 4 whereas in Figure IB the detection station 7 in the form of the UE is separate from the gNB 4 which acts as a 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, the gNB 4, which provides a cell represented by dashed line 12 controls the CWE 3 to transmit the CW 2. 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 A-IoT device to transmit data in the uplink by backscattering another signal (for example the DL signal from the gNB 4). 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 3 and 4. 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. Although Figures 1A and IB describe A-IoT devices performing data transmission based on backscattered signals, the present disclosure is not so limited and any low power or ultra-low power devices generating its own RF signal are also envisaged. Figures 2A and 2B provide alternative scenarios in which a reader of a tag / A-IoT device 1 transmits a reader to device (R2D) signal 21 to the tag / A-IoT device 1. In Figure 2A, the reader is a gNB 4 and in Figure 2B the reader is a UE 7. In some examples the reader may also receive a backscattered signal 5 reflected or backscattered by the tag / A-IoT device 1. Example embodiments described below relate to a design of the R2D signal 21. A problem addressed by the present technique concerns a need for the tags to synchronise with information transmitted in the R2D signal. The tags / A-IoT devices 1 may be of low complexity and have low accuracy clocks in order to reduce device complexity and to reduce 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 Synchronization Signal Block (SSB)) as the tag’s clock would drift in the meantime. The low complexity of the tag / A-IoT device means that there may be limited processing capability for both cost and power consumption reasons and it is likely to be challenging to maintain an accurate clock frequency. The sampling frequency offset (SFO) can reach 104 or 105 parts per million (ppm) and can depend on device type. A type 1 device is a very low cost, low power and low complexity device and may use a ring oscillator with a frequency accuracy of 105 parts per million (ppm). In contrast, a type 2a or 2b device can tolerate higher cost, higher power consumption and higher complexity. These type 2a or 2b devices may use an RC or crystal oscillator having a frequency accuracy of 103 or 104 parts per million (ppm). The frequency accuracy impacts the SFO directly. It is hence apparent that the initial SFO may relate to the device type. The SFO of a device can alternatively be determined by a reader from a measurement performed by the reader during a protocol exchange involving D2R signals that are sent by the tag / A-IoT device. In this case, the reader can measure the SFO on the D2R signals and determine that that SFO will also be applied by the tag / A-IoT device when the tag / A-IoT device decoding R2D signals. A tag / A-IoT device will have a small energy store; hence reception and transmission procedures can only consume small amounts of power. The device may hence not be capable of performing complicated signal processing algorithms. Although Figures 2A and 2B describe A-IoT devices performing data transmission based on backscattered signals, the present disclosure is not so limited and any low power or ultra-low power devices generating its own RF signal are also envisaged. 5G New Radio (NR) Wireless Communications System As indicated above, example embodiments utilise and / or form part of components of the wireless communications network as illustrated in Figures 1A and IB and 2A and 2B. An example configuration of a wireless communications network which uses some of the terminology proposed for NR is shown in Figure 3. In Figure 3 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 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 dashed line 12. As such, wireless communications devices 7, 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 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. The central unit 40 is then connected to a core network 20 which may contain all other functions required for communicating data to and from the wireless communications devices and the core network 20. The core network 20 may be connected to other radio networks and infrastructure equipment. The elements of the wireless access network shown in Figure 3 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 3 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 3 may in part have a corresponding functionality to a base station or eNodeB of an LTE network. It will be appreciated, therefore, that operational aspects of an NR 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 an NR network will be functionally similar to, respectively, the core network component, base stations and communications devices of an LTE wireless communications network. Base stations, which are an example of network infrastructure equipment, may also be referred to as transceiver stations, nodeBs, e-nodeBs, eNB, g-nodeBs, gNB and so forth. In this regard different terminology is often associated with different generations of wireless telecommunications systems for elements providing broadly comparable functionality. However, certain embodiments of the disclosure may be equally implemented in different generations of wireless telecommunications systems, and for simplicity certain terminology may be used regardless of the underlying network architecture. That is to say, the use of a specific term in relation to certain example implementations is not intended to indicate these implementations are limited to a certain generation of network that may be most associated with that particular terminology. As such, the terms infrastructure equipment, base station, transceiver stations, nodeBs, e-nodeBs, eNB, g-nodeBs, and gNB are used interchangeably in the present disclosure. The term network infrastructure equipment / access node may be used to encompass the central unit 40 and associated DU 42 and TRP 10 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 CU 40, DUs 42 and / or TRPs 10. Communications devices 7 are represented in Figure 3 within the coverage area of respective communication cells 12. These communications devices 7 may thus exchange signalling with the CU 40 via the TRP 10 associated with their respective communications cells 12. It will further be appreciated that Figure 3 represents merely one example of a proposed architecture for an NR-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. A more detailed diagram of some of the components of the network shown in Figure 3 is provided by Figure 4. In Figure 4, a TRP 10 as shown in Figure 3 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which is configured to control the transmitter 30 and the receiver 32 to transmit radio signals to and receive radio signals from one or more UEs 7 within a cell 12 formed by the TRP 10. As shown in Figure 4, an example UE 7 is shown to include a corresponding wireless transmitter 49, wireless receiver 48 and a controller or controlling processor 44 which is configured to control the transmitter 49 to transmit signals representing uplink data to the wireless communications network via the wireless access interface formed by the TRP 10 and the receiver 48 to receive downlink data as signals transmitted by the transmitter 30 in accordance with the conventional operation. 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 filters 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 interface 46 between the DU 42 and the CU 40 is known as the Fl 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, for example, may be formed from a fibre optic or other wired 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 TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40. RF Incident Energy As explained above with reference to the example shown in Figures 1 A, IB, 2A and 2B, Ambient loT proposes to use energy received from a radio frequency carrier wave in order to power devices. An Ambient loT device 1 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. Backscattering Principle As explained above with reference to Figures 1 A, IB, 2A and 2B, 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. 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 5 illustrates a generic form of the backscattering circuitry including a matching network and an integrated circuit (IC). There are two aspects of power that are relevant to the Ambient loT device: • Absorbed power. This is the power that is energy harvested and can be used to drive the circuits within the tag. • Reflected power. This is the power that is reflected as a backscattered signal. Given the antenna and load impedances denoted as Za = Ra + jXa and Zn = Rn + jXn, n = 1,2, respectively, the reflection coefficient corresponding to each state is expressed as Zn-z: •p __ n d n — 7 + Z where * denotes the complex conjugate operation. Note that Figure 5 shows the antenna impedance Za as Zant. Note that it is possible for the load impedance to vary between more than two states, while in the present disclosure we consider binary state switching for the sake of simplicity. Ideally, when the load impedance is set to the complex conjugate of the antenna impedance at a certain state, n = 1, = Z*a, F, = 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 Zn that is much greater than Za will lead to a reflection coefficient close to 1, leading to a higher reflection state. Note that in practice, the reflection coefficient |Fn | depends on the manufacturing process and may vary within the range of (0,1). The absorbed power can be calculated as P^n = ^avail(l “ 1^(2) where Pavail denotes the power delivered from the antenna when the load impedance perfectly matches with the antenna impedance. In the literature the power transmission coefficient [5,6] is defined as: ^PnPa T = 1 - r 2 = ---- n 1 nl \zn+za\2 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. Given Pavau, the average power absorbed by the device can be calculated as Pm = P„«| (P1(1 - irl2) + p2(i - |r2|2)) Where pn,n=i,2 denote the ratio of time duration for each impedance state; p± = p2 holds if the probability of each impedance equals to the other (this also means that the same probability of Os and Is appears in the encoded data if the backscattered signal uses a pure OOK waveform). CW Emitter As explained above with reference to Figures 1 A, IB, 2A and 2B, carrier-wave emitters (or CW emitter / CWE) can transmit a carrier wave signal (CWS) that can be used by the tag to backscatter a signal from. As explained above, the CWE may form part of a reader or detector and the CWS may be the R2D signal transmitted by the reader. 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). The scenario is shown in Figure 6. Figure 6 shows a tag 1 with a backscattering module 70. The backscattered signal is backscattered on the CW signal by the backscattering circuit, which may have the structure shown in Figure 5. The tag 1 includes an energy harvesting module 72, which converts energy of the carrier wave signal into power to drive a microcontroller 74 and the backscattering module 70. More explanation of the role and functionality of the CWE and CWS is described in European patent application 24192725.0, the contents of which are incorporated herein by reference. Although embodiments of the present disclosure describe A-IoT devices performing data transmission based on backscattered signals, it is envisaged that the various concepts of uplink contention free channel access described herein may be equally employed for other types of low power or ultra-low power devices that generate its own RF signals. A-IoT uplink contention free channel access with reduced overhead As discussed above, to meet design targets and use cases where existing 3GPP LPWA loT solution are not able to compete, 3GPP study has been carried out targeting to standardize a system for connecting ultra-low power and / or ultra-low complexity A-IoT devices in cellular networks. In terms of energy storage, the study considers two main types of device characteristics. The first type is an extremely low energy storage limited device, capable of consuming only 1 pW in peak power consumption. The second type has more energy storage and aims to support power consumption less than a few hundred pW. Both the first type and the second type A-IoT devices may have their uplinks based on backscattering transmission. The second type of A-IoT devices may also conduct their own uplink transmission in a conventional way. In order for these A-IoT devices to access the channel resources, methods consuming very low amount of energy are required. Embodiments of the present technique provides a method to schedule an A-IoT device in uplink, i.e., device-to-reader direction. The initial channel access attempt may be made by a locally unique parameter, or a short version thereof, that is mapped to a reoccurring slot of a slotted based channel access procedure. In some embodiments, a slot may be a basic time unit of channel resource scheduling and may comprise a discrete number of OFDM symbols. The time unit may comprise of discrete number of chip duration or bits of R2D or D2R symbols. This is technically advantageous particularly for the uplink case where the A-IoT device may not be able to keep the timing to OFDM symbols. In some embodiments, the parameter may be shared within a group of A-IoT devices, such as A-loT devices belonging to the same type, or having similar device characteristics, such as A-IoT devices having similar energy storage size, energy harvesting capability, or power consumption. In other examples, the same group of A-IoT devices may have a comparable distance between the A-IoT device and the reader device, or a comparable distance between the A-IoT device and the carrier wave emitter. In addition, it has been set out that the objective of the 3GPP study for item Ambient loT (Revised SID, RP-240826) concerns light weight signalling procedures enabling Device Originated - Device Terminated Triggered (DO-DTT) and Device Terminated (DT) data transmission. DO-DTT data transmission is intended for uplink, i.e. D2R transmissions that are triggered / controlled from network side. DT data transmission is intended for sending DL / R2D command to the A-IoT devices. Although embodiments of the present technique focus on the case of DO-DTT data transmission, it is envisaged that the technique described herein may be equally employed for any uplink related case, e.g. Device Originated (DO) transmission. In A-IoT devices, energy is considered to be constrained. The interval between an R2D control information reception and a subsequent D2R transmission may depend on the amount of available energy at the A-IoT device. In addition, the R2D control signal may be a command, such as an inventory, triggering many devices at the same time. This means that all of these triggered devices may need to access the channel at the same time. Therefore, there is a need for an improved channel access mechanism that is suitable for power constrained A-IoT devices. Furthermore, it has been discussed how an A-IoT device accesses the channel resources to perform D2R transmission. The two known methods are contention based and contention free channel access. The former may lead to collision while the latter is done based on scheduling and therefore there is no collision. In the 3GPP legacy methods, the initial access is referred to as a sequence of process between UE and Network in order for UE to acquire uplink synchronization and obtain specified ID for the radio access communication. This can be done in a 2-step or 4-step Random Access Channel (RACH) procedure. Nevertheless, both the RACH configuration and its procedures become very energy costly for A-IoT devices with limited energy resources. Additionally, the A-IoT device may need to receive and decode downlink control signal every time it needs to access the channel. The 3GPP study on A-IoT technology and some initial design targets, requirements, topologies, deployment scenarios, etc., are discussed in a technical report TR38.848. There are also extensive ongoing discussions of the topic in RANI 3GPP agenda Item 9.4.2.2. Specifically, a summary of the latest discussions for random access is set out in section 4 of RI-2409244. Embodiments of the present disclosure provide an energy efficient contention free channel access signaling method for A-IoT devices to access the channel resources. The present disclosure can help address or mitigate at least some of the issues discussed above, and particularly, reduce congestion caused by reader devices triggering multiple A-IoT devices simultaneously. Parameter Embodiments of the present technique provides a channel access method that comprises signalling a parameter for scheduling D2R data package to physical resources. Specifically, the method comprises the reader device transmitting, to one or more A-IoT devices, the parameter as a schedule command to schedule physical resources for R2D or D2R data transmission, in which the physical resources are scheduled based on a device type of the one or more A-IoT devices. Subsequently, the reader device performs data transmission with the one or more A-IoT devices using the scheduled physical resources. In some embodiments of the present technique, the data transmission via the scheduled physical resources may be performed in response to a triggering signal, which may be generated by the reader device or the A-IoT device. In the case where the triggering signal is generated by the reader, the parameter may be signaled as part of the triggering signal. In some embodiments, the physical resources may be scheduled in time domain, frequency domain, or a combination of both. The parameter may be signalled by user specific physical layer control, data information or as higher layer parameter. In some embodiments, the parameter may include a device identifier of the A-IoT device, or a short version the device identifier. Figure 7 schematically represent an example of communications systems in which a plurality of A-IoT devices are deployed within partially overlapping coverage areas of two reader devices. Although Figure 7 shows only two reader devices, but the present disclosure is not so limited and any number of reader devices and A-IoT devices is envisaged. According to some embodiments of the present technique, the parameter may be locally unique in the geographic vicinity of a reader device. In some embodiments, the reader may signal the parameter to the A-IoT devices within its coverage area when the reader communicates with the A-IoT device in direct R2D communication, for instance as part of a triggering signal or the data part of a triggering command. In some other embodiments, the signalling can also be performed well in advance of the R2D transmission. According to embodiments of the present technique, the parameter may be reader dependent. In other words, each A-IoT device may have mapped its D2R data differently depending on the reader device (e.g.: based on reader device ID) triggering the data transmission of the A-IoT device. In the example scenario of Figure 7, the A-IoT devices DI, D2 in the coverage area of the reader device RI may be scheduled for physical resources that are different to physical resources of the A-IoT device D3 within the coverage area of the reader device R2. As for A-IoT device D4, which is in the overlapping coverage area under both reader devices RI and R2, the A-IoT device may be scheduled for multiple physical resources respectively for reader devices RI and R2. In some embodiments, A-IoT device D4 may have one resource configuration for reader device RI and a different configuration for reader device R2. In some embodiments, A-IoT device D4 may have the same resource configuration for reader device RI and reader device R2. According to embodiments of the present technique, the parameters for multiple A-IoT devices may be known and coordinated among the reader devices. For example, the coordination can be done at network level or by one or several reader devices. The coordination between the reader devices may be carried out in order to minimize interference, such as any device-to-reader based interference in the case where the A-IoT device is within coverage of multiple reader devices. This is particularly the case when intermediate nodes, e.g., UE devices, are used as reader devices. Figures 8 to 10 illustrate examples of channel access for two A-IoT devices (Device 1 and Device 2) based on TDMA and FDMA in accordance with embodiments of the present disclosure. Although Figures 8 to 10 show only two A-IoT devices, but the present disclosure is not so limited and any number of A-IoT devices is envisaged. Figure 8 and Figure 9 both involve TDMA based scheduling. According to the example embodiment in Figure 8, the physical resources are scheduled as semi-persistent resources on a plurality of consecutive time slot. In particular, each A-IoT device is assigned to several consecutive time units X (here X=2) such that A-IoT Device 1 using resources A (Al and A2) is scheduled in two sequential time-units, slots SI and S2, whereas A-IoT Device 2 using resources B (Bl and B2) is scheduled in slots S3 and S4 after the A-IoT Device 1 resources. According to the example embodiment in Figure 9, the A-IoT device is assigned to reoccurring time slots separated by a plurality of time units as semi-persistent resource allocation. In particular, the A-IoT devices are scheduled in reoccurring slots with a time gap (e.g.: 6 time units) in between the possible slots, such that A-IoT Device 1 is scheduled in slots SI and S8, whereas A-IoT Device 2 is scheduled in slots S2 and S9, with an offset compared to the slots for A-IoT Device 1. In some embodiments, the scheduling of reoccurring slots and time gap in between are based on energy storage size of the A-IoT device, energy harvesting capability of the A-IoT device, power consumption of the A-IoT device, distance between the A-IoT device and the reader device, or distance between the A-IoT device and a carrier wave emitter. According to the example embodiment in Figure 10, a combination of TDMA and FDMA is used for scheduling where the two A-IoT devices are scheduled to access the channel at the same reoccurring time-unit resources but at different frequency resources. In particular, resources Al, A2 for A-IoT Device 1 is scheduled in reoccurring slots (SI and S8) with a time gap (e.g.: 6 time unit) in between the possible slots. Likewise for A-IoT Device 2 but here Device 1 and Device 2 are scheduled in same time slots but different frequency resources. In the example embodiments of Figures 8 to 10, uplink time-unit of the A-IoT devices as a time slot may be several NR Orthogonal frequency-division multiplexing (OFDM) symbols. However, the disclosure is not so limited and it is envisaged that the uplink time-unit of the A-loT devices does not necessarily align with NR. For example, a time-slot or a time-unit may be one or several chips duration of an uplink D2R or downlink R2D signal or symbols. According to embodiments of the present technique, CDMA based channel access in D2R transmission may also be applied. Optionally or additionally, CDMA may be used for channel access in D2R transmission together with TDMA, FDMA, or both. Accordingly, the parameter may point at TDMA, FDMA or CDMA, as well as a combination thereof. Scheduling life cycle Figure 11 is an illustrative representation of an example scheduling life cycle for a communications system comprising A-IoT devices and reader devices in accordance with embodiments of the present disclosure. It is noted that the triggering of an A-IoT device may have an extensive amount of control overhead. According to embodiments of the present technique, a semi-persistent scheduling technique is applied in which a trigger command may precede an R2D or an D2R transmission with the transmission to take place within a time window of a minimum and maximum defined time. In some embodiments, the scheduling technique described above may be valid for a longer time period. For example, the scheduling may be valid for an infinite amount of time or until a new command / scheduling is communicated, as illustrated in Figure 11. This means the A-IoT device may receive just a triggering signal to perform the intended communication, without specifying the scheduling information, for example. The arrangement is particularly advantageous due to the resources can be saved and control / data information overhead can be minimized. According to embodiments of the present technique, the channel access method may involve transparent physical control information. For instance, a scheduling may be seen as a reoccurring pattern where a device may respond in dedicated resources. In some embodiments, the scheduling may be aborted or reconfigured with a new control information communicated, for example, with the transmission of another parameter. In some embodiments, the A-IoT device may comprise a timer and the scheduling is valid for a defined time until the timer expires. Although Figure 11 shows scheduling data for D2R transmission, it is envisaged that the technique is also applicable to R2D transmission. By communicating the scheduling of channel access as a semi-persistent scheduling, the overhead of control information can be reduced as long as the number of reconfigurations is lower than the number of data packages. As mentioned earlier, the scheduling command, or parameter, according to embodiments of the disclosure can be part of an R2D control information or R2D data information. In some embodiments, it may be a fix command length structure in a physical layer, a variable length command structure or a higher layer command. Additionally, the command may partially or fully update or reconfigure a scheduling. The command may also update other parts of the control information and not only the scheduling information. Congestion If there are more devices than physical resources to schedule at, there is a possible case of congestion, or collision. According to some embodiments of the present disclosure, where congestion is detected, the A-IoT device may try to perform the transmission again using the same physical resource but at a later time. Optionally or additionally, time slots different from the scheduled time slots may be assigned for secondary transmission attempts. In other words, the reader device may assign a retransmission to certain specific slots or frames intended for the secondary transmission attempts. Those specific slots may be, e.g., placed sparsely, but be known to the A-IoT devices from, e.g. reading R2D preamble and resolving a frame structure / timing. Within those special slots, random retransmission attempts may be performed, such as transmission attempts based on slotted ALOHA scheme. In some embodiments, where the network / reader device notice a possible congestion, it may use group-based scheduling rather than broadcast, to limit the number of responding devices and thereby reduce congestion. The above-described embodiments of the present technique concern a contention-free channel access scheme for data transmission, and particularly for D2R data transmission, between A-IoT devices and reader devices. Specifically, a parameter that points at an initial resource for D2R channel access may be signaled by the reader device to the A-IoT devices. The parameter may point at TDMA, FDMA or CDMA, as well as a combination thereof. The parameter may be part of a local A-IoT device ID, or a shorter version of the A-IoT device ID. The parameter may be a unique value from e.g. HL signaling or LL signaling (LI Ctrl information). The parameter may be locally unique for a A-IoT device, or may be shared by a group of A-IoT devices. The parameter may be based on the number of responses received by the reader device, i.e. number of responding A-IoT devices in vicinity of the reader device during discovery or on-boarding. The parameters may be based on energy storage size of the A-IoT device, energy harvesting capability of the A-IoT device, power consumption of the A-IoT device, distance between the A-loT device and the reader device, or distance between the A-IoT device and a carrier wave emitter. Additionally, some embodiments of the present technique concern a semi-persistent channel access and scheduling. The A-IoT device may use the scheduled physical resources for subsequently triggered data transmission. For instance, a scheduling command of a channel access is a valid scheduling until aborted or reconfigured. Furthermore, the data transmission may be trigged (using already scheduled resources) both for single and multiple resources. By scheduling the physical resources as semi-persistent resources, the scheduling remains valid for an infinite amount of time until a new scheduling command is communicated, data of unknown length / duration may therefore be transmitted by the A-IoT devices. In some embodiments, a group-based trigger command (trigger signal) may be used to mitigate congestion, for example, by sharing the parameter among a group of A-IoT devices. Figure 12 shows a signal flow diagram representation of an example communications system comprising A-IoT devices, reader devices and an infrastructure equipment in accordance with embodiments of the present technique. Although Figure 12 shows that the reader device and the infrastructure equipment are separate devices, it is envisaged that the reader device and the infrastructure equipment may be the same device, and the signalling between reader device and the infrastructure equipment as described in Figure 12 may be internal signalling within the same device. In Figure 12, signal flow 1201 includes parameters transmitted from an infrastructure equipment 1210 in the network, such as a gNB, to a reader device 1220, such as a UE-based reader device. The parameters provided from the network schedule physical resources for data transmission, particularly D2R data transmission, between the reader device 1220 and A-IoT device 1230. Next, the reader device 1220 forwards the parameters provided from the network to A-IoT device 1230 as parameters via signal flow 1202. According to some embodiments of the present technique, the A-IoT device 1230 receives a triggering signal from an application 1240 within the A-IoT device 1230 via signal flow 1203, and is triggered autonomously by the application 1240 to perform uplink channel access for data transmission. According to some other embodiments of the present technique, the A-IoT device 1230 receives a triggering signal from the reader device 1220 via signal flow 1204 which triggers the A-IoT device to perform uplink channel access for data transmission. In some embodiments, the parameter may be part of the triggering signal sent by the reader device 1220, hence signal flow 1202 is combined with signal flow 1204. After receiving the triggering signal, either via signal flow 1203 or signal flow 1204, the A-IoT device 1230 evaluate scheduling from the parameter and performs a mapping from the parameter to a corresponding uplink resource. Subsequently, the A-IoT device 1230 performs D2R data transmission via signal flow 1205 using the scheduled uplink resource. Optionally or additionally, the reader device 1220 further forwards the data from A-IoT device 1230 to the gNB 1210 via signal flow 1206, using legacy methods. Figure 13 shows another signal flow diagram representation of an example communications system comprising A-IoT devices, reader devices and an infrastructure equipment in accordance with embodiments of the present technique. Although Figure 13 shows that the reader device and the infrastructure equipment are separate devices, it is envisaged that the reader device and the infrastructure equipment may be the same device, and the signalling between reader device and the infrastructure equipment as described in Figure 13 may be internal signalling within the same device. In Figure 13, signal flow 1301 includes parameters transmitted from an infrastructure equipment 1310 in the network, such as a gNB, to a reader device 1320, such as a UE-based reader device. The parameters provided from the network schedule physical resources for data transmission, particularly D2R data transmission, between the reader device 1320 and A-IoT device 1330. Next, the reader device 1320 forwards the parameters provided from the network to A-IoT device 1330 as parameters via signal flow 1302. According to some embodiments of the present technique, the reader device 1320 combines a triggering signal with the parameters in the signal flow 1302. In some other embodiments, the reader device 1320 may transmit the triggering signal to the A-IoT 1330 via a separate signal flow (not shown), as previously discussed in Figure 12. In some other embodiments of the present technique, the A-IoT device 1330 may receive a triggering signal instead from an application (not shown) within the A-IoT device, as previously discussed in Figure 12. After receiving the triggering signal, the A-IoT device 1330 evaluates scheduling from the parameter and performs a mapping from the parameter to a corresponding uplink resource. Subsequently, the A-IoT device 1330 performs D2R data transmission via signal flow 1303 using the scheduled uplink resource. Optionally or additionally, the reader device 1320 further forwards the data from A-IoT device 1330 to the gNB 1310 via signal flow 1304, using legacy methods. In signal flow 1305, the reader device 1320 sends a second triggering signal to the A-IoT device 1330. Since the previously scheduled resources are semi-persistently allocated for the A-IoT device 1330, successive data transmission can be performed on these previously scheduled resources, and the reader device 1320 does not need to send parameter to the A-IoT device 1330 for the successive data transmission. Upon receiving the triggering signal, the A-IoT device 1330 performs D2R data transmission via signal flow 1306 using the persistently scheduled uplink resource. Optionally or additionally, the reader device 1320 further forwards the data from A-IoT device 1330 to the gNB 1310 via signal flow 1307, in accordance with legacy methods. In both Figure 12 and Figure 13, an onboarding phase for discovering the A-IoT devices is omitted and is assumed to occur in advance of usage of the method according embodiments of the present technique. Although Figure 12 and Figure 13 describe that the parameter is used for determination of uplink resources, the present disclosure is not so limited and it is envisaged that the concept of scheduling described herein may be equally employed for downlink scheduling determination. Figure 14 shows a flow diagram illustrating a method of operating a reader device in accordance with example embodiments of the present technique. The process shown by Figure 14 is specifically a method of operating a reader device (e.g. UE-based reader device or a base stationbased reader device) forming part of a wireless communications network and configured to transmit signals to and / or to receive signals from one or more low power devices such as A-IoT devices. The method begins in step Sil. The method comprises, in step S12 transmitting, to the one or more A-IoT devices, a parameter as a schedule command to schedule physical resources for reader-to-device (R2D) or device-to-reader (D2R) data transmission, the parameter comprising information for mapping the physical resources. A sufficient time-gap between D2R and R2D transmissions may be considered to accommodate frequency error caused by SFO / CFO or other circuitry aspects needed to be taken into account. The time-gap may be different depending on the device type and its characteristics. The time-gap may be taken into account when associating R2D resources in relation to D2R resources. Subsequently, in step S13, the method comprises performing data transmission with the a first A-loT devices using the scheduled physical resources. The process ends in step S14. In some embodiments, the information for mapping the physical resources may comprise a device identifier of the first low power device or a short version thereof. In some embodiments, the device identifier may be locally unique in the geographic vicinity of the reader device and / or the A-IoT device. In some embodiments, the data transmission via the scheduled physical resources may be performed in response to a triggering signal. Furthermore, the triggering signal may be generated by the reader device or the A-IoT device, in which case, the method may comprise signalling the parameter as part of the triggering signal. In some embodiments, a sufficient time-gap between D2R and R2D transmissions may be considered to accommodate frequency error caused by SFO / CFO or other circuitry aspects needed to be taken into account. The time-gap may be different depending on the device type and its characteristics. The time-gap may be taken into account when associating R2D resources in relation to D2R resources. According to some embodiments of the present technique, the parameter may point at TDMA resources, and the data transmission may be assigned with one or more time slots of the TDMA resources. In some other embodiments, the parameter may point at FDMA resources, and the data transmission may be assigned with one or more channels of the FDMA resources. In some further embodiments, the parameter may point at CDMA resources, and the data transmission may be assigned with one or more codes of the CDMA resources. The parameter may point at a combination of TDMA resources, FDMA resources and CDMA resources. The parameter may be signalled by user specific physical layer control, data information or higher layer parameter. The parameter also may be locally unique in the geographic vicinity of the reader device. According to some embodiments of the present technique, the physical resources may be scheduled as semi-persistent resources on a plurality of consecutive time slot. On the other hand, the A-IoT device may be assigned to reoccurring time slots separated by a plurality of time slots as semi-persistent resource allocation, in which each time slot may comprise a plurality OFDM symbols, or one or several chip duration of R2D or D2R signal. According to some embodiments of the present technique, the A-IoT device may be scheduled for different physical resources depending on which reader device triggers the data transmission of A-loT device. In some embodiments, the wireless communications network may include a plurality of reader devices, the parameters for the one or more A-IoT devices may then be coordinated among the plurality of reader devices to minimize interference. According to some embodiments of the present technique, the scheduling may be semi-persistent scheduling being valid for a predetermined period of time or until another parameter is transmitted. Additionally, the scheduling may be aborted or reconfigured with the transmission of another parameter. The scheduling may also be partially or fully reconfigured by the other parameter. According to some embodiments of the present technique, the parameter may be part of control information or data information transmitted from the reader device to the A-IoT device. The parameter may be a fix command length structure in a physical layer, a variable length command structure in a physical layer, or a higher layer command. According to some embodiments of the present technique, where congestion is detected, the method may comprise performing data transmission again using the scheduled physical resource after a predetermined period of time. According to some other embodiments of the present technique, where congestion is detected, the method may comprise assigning time slots different from the scheduled time slots for secondary transmission attempts. According to some other embodiments of the present technique, where congestion is detected, the method may comprise transmitting parameter for scheduling data transmission to physical resources by group-based scheduling. In some embodiments, the assigned time slots may be placed sparsely but be known to the A-IoT devices from reading the parameter and resolving a frame structure / timing. Within the scheduled physical resources it may be allowed for random retransmission attempts. According to some other embodiments of the present technique, the parameter may be based on factors including: the number of responding A-IoT devices, energy storage size of the A-IoT device, energy harvesting capability of the A-IoT device, power consumption of the A-IoT device, distance between the A-IoT device and the reader device, and distance between the A-IoT device and a carrier wave emitter. The physical resources may be scheduled based on a device type of the one or more A-IoT devices. The data transmission using scheduled physical resources may be triggered both for single and multiple physical resources. Furthermore, the A-IoT device may use the scheduled physical resources for subsequently triggered data transmission. According to some other embodiments of the present technique, the reader device may be a base station or a user equipment (UE). In some embodiments, a UE-based reader device may be an intermediate node, and the resources from the intermediate node to the low power devices may be assigned to the intermediate node by a base station. Figure 15 shows a flow diagram illustrating a method of operating an A-IoT device in accordance with example embodiments of the present technique. The process shown by Figure 15 is particularly a method of operating an A-IoT device configured to transmit signals to and / or to receive signals from one or more reader devices (e.g. UE-based reader device or a base stationbased reader device) forming part of a wireless communications network. The method begins in step S21. The method comprises, in step S22, receiving, from a first reader device among the one or more reader devices, a parameter as a schedule command to schedule physical resources for reader-to-device (R2D) or device-to-reader (D2R) data transmission, the parameter comprising information for mapping the physical resources. In some embodiments, the information for mapping the physical resources may comprise a device identifier of a first low power device or a short version thereof, and the device identifier may be locally unique in the geographic vicinity of the reader device and / or the first low power device. In step S23, the A-IoT device translates the received parameter into scheduling of the physical resources. Specifically, the parameter might not be a direct indication of the scheduling, and the A-IoT device converts the parameter into scheduling of the resources through a translation process. In some example embodiments, the translation can be done according to predefined or specified rules. In some other example embodiments, the translation can be done by direct mapping based on resource block groups or similar mapping. Next, in step S24, the process comprises performing data transmission with the first reader device using the scheduled physical resources. The process ends in step S25. According to some embodiments of the present technique, the data transmission via the scheduled physical resources may be performed in response to a triggering signal, in which the triggering signal may be generated by the reader device or the A-IoT device. The method may comprise receiving the parameter as part of the triggering signal. According to some embodiments of the present technique, the parameter may point at TDMA resources, and the data transmission may be assigned with one or more time slots of the TDMA resources. In some other embodiments, the parameter may point at FDMA resources, and the data transmission may be assigned with one or more channels of the FDMA resources. In some further embodiments, the parameter may point at CDMA resources, and the data transmission may be assigned with one or more codes of the CDMA resources. The parameter may point at a combination of TDMA resources, FDMA resources and CDMA resources. The parameter may be signalled by user specific physical layer control, data information or higher layer parameter. The parameter also may be locally unique in the geographic vicinity of the reader device. According to some embodiments of the present technique, the physical resources may be scheduled as semi-persistent resources on a plurality of consecutive time slot. On the other hand, the A-IoT device may be assigned to reoccurring time slots separated by a plurality of time slots as semi-persistent resource allocation, in which each time slot may comprise a plurality of OFDM symbols, or one or several chip duration of R2D or D2R signal. According to some embodiments of the present technique, the A-IoT device may be scheduled for different physical resources depending on which reader device triggers the data transmission of A-loT device. In some embodiments, the wireless communications network may include a plurality of reader devices, the parameters for the one or more A-IoT devices may then be coordinated among the plurality of reader devices to minimize interference. According to some embodiments of the present technique, the scheduling may be semi-persistent scheduling being valid for a predetermined period of time or until another parameter is transmitted. Additionally, the scheduling may be aborted or reconfigured with the transmission of another parameter. The scheduling may also be partially or fully reconfigured by the other parameter. According to some embodiments of the present technique, the parameter may be part of control information or data information transmitted from the reader device to the A-IoT device. The parameter may be a fix command length structure in a physical layer, a variable length command structure in a physical layer, or a higher layer command. According to some embodiments of the present technique, where congestion is detected, the method may comprise performing data transmission again using the scheduled physical resource after a predetermined period of time. According to some other embodiments of the present technique, where congestion is detected, the method may comprise performing secondary transmission attempts based on newly assigned time slots different from the scheduled time slots. According to some other embodiments of the present technique, where congestion is detected, the method may comprise receiving parameter for scheduling data transmission to physical resources by group-based scheduling. In some embodiments, the assigned time slots may be placed sparsely but be known to the A-IoT devices from reading the parameter and resolving a frame structure / timing. Within the scheduled physical resources it may be allowed for random retransmission attempts. According to some other embodiments of the present technique, the parameter may be based on factors including: the number of responding A-IoT devices, energy storage size of the A-IoT device, energy harvesting capability of the A-IoT device, power consumption of the A-IoT device, distance between the A-IoT device and the reader device, and distance between the A-IoT device and a carrier wave emitter. The physical resources may be scheduled based on a device type of the one or more A-IoT devices. The data transmission using scheduled physical resources may be triggered both for single and multiple physical resources. Furthermore, the A-IoT device may use the scheduled physical resources for subsequently triggered data transmission. According to some other embodiments of the present technique, the reader device may be a base station or a user equipment (UE). In some embodiments, a UE-based reader device may be an intermediate node, and the resources from the intermediate node to the low power devices may be assigned to the intermediate node by a base station. Those skilled in the art would further appreciate that methods, 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. The methods described herein may also be embodied or encoded in a computer-readable medium, such as a computer-readable storage medium, containing instructions. Instructions embedded or encoded in a computer-readable medium may cause a programmable processor, or other processor, to perform the method, e.g., when the instructions are executed. Computer-readable media may include non-transitory computer-readable storage media and transient communication media. Computer readable storage media, which is tangible and non-transitory, may include random access memory (RAM), read only memory (ROM), programmable read only memory (PROM), erasable programmable read only memory (EPROM), electronically erasable programmable read only memory (EEPROM), flash memory, a hard disk, a CD-ROM, a floppy disk, a cassette, magnetic media, optical media, or other computer-readable storage media. The term “computer-readable storage media” refers to physical storage media, and not signals, carrier waves, or other transient media. As noted above, computer readable media may include transient communication media. Such communication media may occur within a single computer system or between multiple computer systems, and may take the form of transient signal-conveying media such as carrier waves and transmission signals. Therefore, from one perspective there has been described methods, reader devices, communications devices, and circuitry for an energy efficient contention free channel access signaling method for A-IoT devices to access the channel resources. Particular examples of the present disclosure are set out in the following numbered paragraphs: Paragraph 1. A method of operating a reader device forming part of a wireless communications network and configured to transmit signals to and / or to receive signals from one or more low power devices via a radio access interface between the reader device and the one or more low power devices, the method comprising: transmitting, to the one or more low power devices, a parameter as a schedule command to schedule physical resources for reader-to-device (R2D) or device-to-reader (D2R) data transmission, the parameter comprising information for mapping the physical resources , and performing data transmission with a first low power device using the scheduled physical resources. Paragraph 2. A method according to paragraph 1, wherein the information for mapping the physical resources comprises a device identifier of the first low power device or a short version thereof, and the device identifier is locally unique in the geographic vicinity of the reader device and / or the first low power device. Paragraph 3. A method according to paragraph 1, wherein the data transmission via the scheduled physical resources is performed in response to a triggering signal. Paragraph 4. A method according to paragraph 3, wherein the triggering signal is generated by the reader device or the first low power device. Paragraph 5. A method according to paragraph 3 or paragraph 4, comprising signalling the parameter as part of the triggering signal. Paragraph 6. A method according to any of the preceding paragraphs, wherein the parameter points at TDMA resources, the data transmission being assigned with one or more time slots of the TDMA resources. Paragraph 7. A method according to any of the preceding paragraphs, wherein the parameter points at FDMA resources, the data transmission being assigned with one or more channels of the FDMA resources. Paragraph 8. A method according to any of the preceding paragraphs, wherein the parameter points at CDMA resources, the data transmission being assigned with one or more codes of the CDMA resources. Paragraph 9. A method according to any of the preceding paragraphs, wherein the parameter points at a combination of TDMA resources, FDMA resources and CDMA resources. Paragraph 10. A method according to any of the preceding paragraphs, wherein the parameter is signalled by user specific physical layer control, data information or higher layer parameter. Paragraph 11. A method according to any of the preceding paragraphs, wherein the parameter comprises a device identifier of the first low power device or a short version thereof. Paragraph 12. A method according to any of the preceding paragraphs, wherein the parameter is locally unique in the geographic vicinity of the reader device. Paragraph 13. A method according to any of the preceding paragraphs, wherein the physical resources are scheduled as semi-persistent resources on a plurality of consecutive time slot. Paragraph 14. A method according to any of paragraphs 1 to 12, wherein the low power device is assigned to reoccurring time slots separated by a plurality of time slots as semi-persistent resource allocation. Paragraph 15. A method according to paragraph 13 or paragraph 14, wherein each time slot comprises a plurality of OFDM symbols or a plurality of chip duration of R2D or D2R symbols.. Paragraph 16. A method according to any of the preceding paragraphs, wherein the parameter comprises a reader identifier. Paragraph 17. A method according to any of the preceding paragraphs, wherein the wireless communications network includes a plurality of reader devices, the parameters for the one or more low power devices are coordinated among the plurality of reader devices. Paragraph 18. A method according to any of the preceding paragraphs, wherein the scheduling is semi-persistent scheduling being valid for a predetermined period of time or until another parameter is transmitted. Paragraph 19. A method according to any of the preceding paragraphs, wherein the scheduling is aborted or reconfigured with the transmission of another parameter. Paragraph 20. A method according to any of the preceding paragraphs, wherein the scheduling is partially or fully reconfigured by the other parameter. Paragraph 21. A method according to any of the preceding paragraphs, wherein the parameter is part of control information or data information transmitted from the reader device to the first low power device. Paragraph 22. A method according to any of the preceding paragraphs, wherein the parameter is a fix command length structure in a physical layer, a variable length command structure in a physical layer, or a higher layer command. Paragraph 23. A method according to any of the preceding paragraphs, comprising, where congestion is detected, performing data transmission again using the scheduled physical resource after a predetermined period of time. Paragraph 24. A method according to any of the preceding paragraphs, comprising, where congestion is detected, assigning time slots different from the scheduled time slots for secondary transmission attempts. Paragraph 25. A method according to any of the preceding paragraphs, wherein the assigned time slots are placed sparsely but be known to the low power devices from reading the parameter and resolving a frame structure / timing. Paragraph 26. A method according to any of the preceding paragraphs, wherein one or more retransmission attempts are allowed within the scheduled physical resources . Paragraph 27. A method according to any of the preceding paragraphs, comprising, where congestion is detected, transmitting parameter for scheduling data transmission to physical resources by group-based scheduling. Paragraph 28. A method according to any of the preceding paragraphs, wherein the parameter is based on the number of responding low power devices. Paragraph 29. A method according to any of the preceding paragraphs, wherein the parameter is based on energy storage size of the low power device, energy harvesting capability of the low power device, power consumption of the low power device, distance between the low power device and the reader device, or distance between the low power device and a carrier wave emitter. Paragraph 30. A method according to any of the preceding paragraphs, wherein the physical resources are scheduled based on a device type of the one or more low power devices. Paragraph 31. A method according to any of the preceding paragraphs, wherein the data transmission using scheduled physical resources is triggered both for single and multiple physical resources. Paragraph 32. A method according to any of the preceding paragraphs, wherein the low power device uses the scheduled physical resources for subsequently triggered data transmission. Paragraph 33. A method according to any of the preceding paragraphs, wherein the reader device is a base station or a user equipment (UE). Paragraph 34. A method according to any of the preceding paragraphs, wherein the reader device is an intermediate node, the resources from the intermediate node to the low power devices are assigned to the intermediate node by a base station. Paragraph 35. A method according to any of the preceding paragraphs, wherein the low power device is an Ambient loT (A-IoT) device. Paragraph 36. A method of operating a lower power device configured to transmit signals to and / or to receive signals from one or more reader devices forming part of a wireless communications network via a radio access interface between the low power device and the one or more reader devices, the method comprising: receiving, from a first reader device among the one or more reader devices, a parameter as a schedule command to schedule physical resources for reader-to-device (D2R) or device-to-reader (R2D) data transmission, the parameter comprising information for mapping the physical resources; and performing data transmission with the first reader device using the scheduled physical resources. Paragraph 37. A method according to paragraph 36, wherein the information for mapping the physical resources comprise a device identifier, and the device identifier is locally unique in the geographic vicinity of the first reader device and / or the low power device. Paragraph 38. A method according to paragraph 36, wherein the data transmission via the scheduled physical resources is performed in response to a triggering signal. Paragraph 39. A method according to paragraph 38, wherein the triggering signal is generated by the first reader device or the low power device. Paragraph 40. A method according to paragraph 38 or paragraph 39, comprising receiving the parameter as part of the triggering signal. Paragraph 41. A method according to any of paragraphs 36 to 40, comprising translating the parameter received from the first reader device into scheduling of physical resources. Paragraph 42. A method according to any of paragraphs 36 to 41, wherein the low power device is scheduled for different physical resources depending on which reader device triggers the data transmission of low power device. Paragraph 43. A method according to any of paragraphs 36 to 42, wherein the parameter points at TDMA resources, the data transmission being assigned with one or more time slots of the TDMA resources. Paragraph 44. A method according to any of paragraphs 36 to 43, wherein the parameter points at FDMA resources, the data transmission being assigned with one or more channels of the FDMA resources. Paragraph 45. A method according to any of paragraphs 36 to 44, wherein the parameter points at CDMA resources, the data transmission being assigned with one or more codes of the CDMA resources. Paragraph 46. A method according to any of paragraphs 36 to 45, wherein the parameter points at a combination of TDMA resources, FDMA resources and CDMA resources. Paragraph 47. A method according to any of paragraphs 36 to 46, wherein the parameter is signalled by user specific physical layer control, data information or higher layer parameter. Paragraph 48. A method according to any of paragraphs 36 to 47, wherein the parameter comprises a device identifier of the low power device or a short version thereof. Paragraph 49. A method according to any of paragraphs 36 to 48, wherein the parameter is locally unique in the geographic vicinity of the first reader device. Paragraph 50. A method according to any of paragraphs 36 to 49, wherein the physical resources are scheduled as semi-persistent resources on a plurality of consecutive time slot. Paragraph 51. A method according to any of paragraphs 36 to 49, wherein the low power device is assigned to reoccurring time slots separated by a plurality of time slots as semi-persistent resource allocation. Paragraph 52. A method according to paragraph 50 or paragraph 51, wherein each time slot comprises a plurality of OFDM symbols or a plurality of chip duration of R2D or D2R symbols. Paragraph 53. A method according to any of paragraphs 36 to 52, wherein the parameter comprises a reader identifier. Paragraph 54. A method according to any of paragraphs 36 to 53, wherein the wireless communications network includes a plurality of reader devices, the parameters for the one or more low power devices are coordinated among the plurality of reader devices. Paragraph 55. A method according to any of paragraphs 36 to 54, wherein the scheduling is semi-persistent scheduling being valid for a predetermined period of time or until another parameter is transmitted. Paragraph 56. A method according to any of paragraphs 36 to 55, wherein the scheduling is aborted or reconfigured with the transmission of another parameter. Paragraph 57. A method according to any of paragraphs 36 to 56, wherein the scheduling is partially or fully reconfigured by the other parameter. Paragraph 58. A method according to any of paragraphs 36 to 57, wherein the parameter is part of control information or data information transmitted from the first reader device to the low power device. Paragraph 59. A method according to any of paragraphs 36 to 58, wherein the parameter is a fix command length structure in a physical layer, a variable length command structure in a physical layer, or a higher layer command. Paragraph 60. A method according to any of paragraphs 36 to 59, comprising, where congestion is detected, performing data transmission again using the scheduled physical resource after a predetermined period of time. Paragraph 61. A method according to any of paragraphs 36 to 60, comprising, where congestion is detected, receiving assignment of time slots different from the scheduled time slots for secondary transmission attempts. Paragraph 62. A method according to any of paragraphs 36 to 61, wherein the assigned time slots are placed sparsely but be known to the low power devices from reading the parameter and resolving a frame structure / timing. Paragraph 63. A method according to any of paragraphs 36 to 62, wherein one or more retransmission attempts are allowed within the scheduled physical resources . Paragraph 64. A method according to any of paragraphs 36 to 63, comprising, where congestion is detected, receiving parameter for scheduling data transmission to physical resources by group-based scheduling. Paragraph 65. A method according to any of paragraphs 36 to 64, wherein the parameter is based on the number of responding low power devices. Paragraph 66. A method according to any of paragraphs 36 to 65, wherein the parameter is based on energy storage size of the low power device, energy harvesting capability of the low power device, power consumption of the low power device, distance between the low power device and the first reader device, or distance between the low power device and a carrier wave emitter. Paragraph 67. A method according to any of paragraphs 36 to 66, wherein the physical resources are scheduled based on a device type of the one or more low power devices. Paragraph 68. A method according to any of paragraphs 36 to 67, wherein the data transmission using scheduled physical resources is triggered both for single and multiple physical resources. Paragraph 69. A method according to any of paragraphs 36 to 68, comprising using the scheduled physical resources for subsequently triggered data transmission. Paragraph 70. A method according to any of paragraphs 36 to 69, wherein the first reader device is a base station or a user equipment (UE). Paragraph 71. A method according to any of paragraphs 36 to 70, wherein the first reader device is an intermediate node, the resources from the intermediate node to the low power devices are assigned to the intermediate node by a base station. Paragraph 72. A method according to any of paragraphs 36 to 71, wherein the low power device is an Ambient loT (A-IoT) device. Paragraph 73. A communications apparatus operating as a reader device forming part of a wireless communications network, the communications apparatus comprising transceiver circuitry configured to: transmit, to one or more low power devices of the wireless communications network via a radio access interface between the one or more low power device and the reader device, a parameter as a schedule command to schedule physical resources for reader-to-device (R2D) or device-to-reader (D2R) data transmission, the parameter comprising information for mapping the physical resources, and perform data transmission with a first low power device using the scheduled physical resources. Paragraph 74. A low power device, comprising transceiver circuitry configured to: receive, from a first reader device among one or more reader devices of a wireless communications network via a radio access interface between the low power device and the one or more reader devices, a parameter as a schedule command to schedule physical resources for reader-to-device (D2R) or device-to-reader (R2D) data transmission, the parameter comprising information for mapping the physical resources; and perform data transmission with the first reader device using the scheduled physical resources. Paragraph 75. Circuity for a communications device operating as a reader device forming part of a wireless communications network, the circuitry comprising transceiver circuitry configured to: transmit, to one or more low power devices of the wireless communications network via a radio access interface between the one or more low power device and the reader device, a parameter as a schedule command to schedule physical resources for reader-to-device (R2D) or device-to-reader (D2R) data transmission, the parameter comprising information for mapping the physical resources, and perform data transmission with a first low power device using the scheduled physical resources. Paragraph 76. Circuity for a low power device, the circuitry comprising transceiver circuitry configured to: receive, from a first reader device among one or more reader devices of a wireless communications network via a radio access interface between the low power device and the one or more reader devices, a parameter as a schedule command to schedule physical resources for reader-to-device (D2R) or device-to-reader (R2D) data transmission, the parameter comprising information for mapping the physical resources; and perform data transmission with the first reader device using the scheduled physical resources. Paragraph 77. A computer program which, when the program is executed by a computer, cause the computer to perform the method of paragraph 1 or paragraph 36. Paragraph 78. A non-transitory computer-readable storage medium storing a computer program according to paragraph 77. REFERENCES [1] RP-234058, “New SID: Study on solutions for Ambient loT (Internet of Things) in NR”. RAN plenary #102. Edinburgh. December 2023. [2] TR 38.913, “3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14)”, 3GPP, V14.3.0, August 2017. [3] ‘Study Ambient loT (Internet of Things) in RAN’, 3 GPP TR38.848. https: / / www.3gpp.org / ftp / Specs / archive / 38_series / 38.848 / 38848-i00.zip [4] Van Huynh, Nguyen, Dinh Thai Hoang, Xiao Lu, Dusit Niyato, Ping Wang, and Dong In Kim. "Ambient Backscatter Communications: A Contemporary Survey." IEEE Communications Surveys &Tutorials 20, no. 4 (2018): 2889-2922. [5] RP-234065, “New WID: Enhancements of network energy savings for NR,” 3GPP TSG RAN Meeting# 102, Edinburgh, Scotland, December 1 lth-15th, 2023 [6] GSMA, 5G energy efficiencies: Green is the new black, https: / / data.gsmaintelligence.com / api-web / v2 / research-file- download?id=54165956&file=241120-5G-energy.pdf [7] ‘Study Ambient loT (Internet of Things) in RAN’, 3 GPP TR 38.848. https: / / www.3gpp.org / ftp / Specs / archive / 38_series / 38.848 / 38848-i00.zip [8] Rl-2403821 “Report of RAN1#116bis meeting”. ETSIMC, 3GPP TSGRAN WG1 #117, Fukuoka, Japan, May 20th - May 24th, 2024. [9] ‘Draft Report of 3GPP TSG RAN WG1 #117 v0.2.0’, 3GPP TSG RAN WG1 #117, Fukuoka, Japan, May 20th - May 24th, 2024. 28

[10] ‘Study on Low-Power Wake-Up signal and Receiver for NR’, 3GPP TR 38.869. https: / / www.3gpp.org / ftp / Specs / archive / 38 series / 38.869 / 38869-i00.zip

[11] European patent application EP24192725.0

[12] Rl-2409244 Final FL summary on frame structure and timing aspects for Rel-19 Ambient 5 loT Moderator (vivo)

Claims

1. A method of operating a reader device forming part of a wireless communications network and configured to transmit signals to and / or to receive signals from one or more low power devices via a radio access interface between the reader device and the one or more low power devices, the method comprising:transmitting, to the one or more low power devices, a parameter as a schedule command to schedule physical resources for reader-to-device (R2D) or device-to-reader (D2R) data transmission, the parameter comprising information for mapping the physical resources , andperforming data transmission with a first low power device using the scheduled physical resources.

2. A method according to claim 1, wherein the information for mapping the physical resources comprises a device identifier of the first low power device or a short version thereof, and the device identifier is locally unique in the geographic vicinity of the reader device and / or the first low power device.

3. A method according to claim 1, wherein the data transmission via the scheduled physical resources is performed in response to a triggering signal.

4. A method according to claim 3, wherein the triggering signal is generated by the reader device or the first low power device.

5. A method according to claim 3 or claim 4, comprising signalling the parameter as part of the triggering signal.

6. A method according to any of the preceding claims, wherein the parameter points at TDMA resources, the data transmission being assigned with one or more time slots of the TDMA resources.

7. A method according to any of the preceding claims, wherein the parameter points at FDMA resources, the data transmission being assigned with one or more channels of the FDMA resources.

8. A method according to any of the preceding claims, wherein the parameter points at CDMA resources, the data transmission being assigned with one or more codes of the CDMA resources.

9. A method according to any of the preceding claims, wherein the parameter points at a combination of TDMA resources, FDMA resources and CDMA resources.

10. A method according to any of the preceding claims, wherein the parameter is signalled by user specific physical layer control, data information or higher layer parameter.3011. A method according to any of the preceding claims, wherein the parameter comprises a device identifier of the first low power device or a short version thereof.

12. A method according to any of the preceding claims, wherein the parameter is locally unique in the geographic vicinity of the reader device.

13. A method according to any of the preceding claims, wherein the physical resources are scheduled as semi-persistent resources on a plurality of consecutive time slot.

14. A method according to any of claims 1 to 12, wherein the low power device is assigned to reoccurring time slots separated by a plurality of time slots as semi-persistent resource allocation.

15. A method according to claim 13 or claim 14, wherein each time slot comprises a plurality of OFDM symbols or a plurality of chip duration of R2D or D2R symbols..

16. A method according to any of the preceding claims, wherein the parameter comprises a reader identifier.

17. A method according to any of the preceding claims, wherein the wireless communications network includes a plurality of reader devices, the parameters for the one or more low power devices are coordinated among the plurality of reader devices.

18. A method according to any of the preceding claims, wherein the scheduling is semi-persistent scheduling being valid for a predetermined period of time or until another parameter is transmitted.

19. A method according to any of the preceding claims, wherein the scheduling is aborted or reconfigured with the transmission of another parameter.

20. A method according to any of the preceding claims, wherein the scheduling is partially or fully reconfigured by the other parameter.

21. A method according to any of the preceding claims, wherein the parameter is part of control information or data information transmitted from the reader device to the first low power device.

22. A method according to any of the preceding claims, wherein the parameter is a fix command length structure in a physical layer, a variable length command structure in a physical layer, or a higher layer command.

23. A method according to any of the preceding claims, comprising, where congestion is detected, performing data transmission again using the scheduled physical resource after a predetermined period of time.

24. A method according to any of the preceding claims, comprising, where congestion is detected, assigning time slots different from the scheduled time slots for secondary transmission attempts.

25. A method according to any of the preceding claims, wherein the assigned time slots are placed sparsely but be known to the low power devices from reading the parameter and resolving a frame structure / timing.s

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