Communications system, detection station, carrier wave emitter, and methods

Abstract

A communications system comprises one or more tags, a controller station, one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the one or more tags, and a detector station. The detector station is configured to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the carrier wave emitter, wherein the controller station is connected to the one or more carrier wave emitters via an interface and is configured to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags. In some examples, the controller station and the detection station are formed by the same device such as an infrastructure equipment of a wireless communications network. In other examples the controller station is formed from an infrastructure equipment and the detection station is formed from a communications device which communicates with the infrastructure equipment. In some examples, the controller station may control the one or more carrier wave emitter in response to the backscattered signals detected from one or more of the tags. Accordingly an advantage can be provided by controlling the carrier wave emitters to reduce interference and reduce power consumption by adjusting transmission of the carrier wave signals in response to the detected backscattered signals so that a power of the carrier wave signals can be adjusted and this can be controlled to only be transmitted when our tags present.

Description

[0001] COMMUNICATIONS SYSTEM, DETECTION STATION, CARRIER WAVE EMITTER, AND METHODS

[0002] BACKGROUND

[0003] Field of the Disclosure

[0004] The present disclosure relates to detection stations of communication system for detecting backscattered signals by tag, which are backscattering a carrier wave signal transmitted by carrier wave emitter. In one example, the detection stations may be infrastructure equipment of a wireless communications network. The present disclosure also relates to carrier wave emitters, tags and methods.

[0005] The present invention claims the Paris convention priority to European patent application EP24158497.8 filed on 19 February 2024, the contents of which are incorporated by reference in its entirety.

[0006] Background

[0007] 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.

[0008] Recent generation mobile telecommunication systems, such as those based on the 3rdGeneration Partnership Project (3GPP (RTM)) defined Universal Mobile Telecommunications System (UMTS), Long Term Evolution (LTE) and 5G New Radio (NR) architectures, are able to support a wider range of services than simple voice and messaging services offered by previous generations of mobile telecommunication systems. For example, with the improved radio interface and enhanced data rates provided by LTE and NR systems, a user is able to experience high data rate applications such as mobile video streaming and mobile video conferencing that would previously only have been available via a fixed line data connection. In addition to supporting these kinds of more sophisticated services and devices, it is also proposed for newer generation mobile telecommunication systems such as NR to support less complex services and devices which make use of the reliable and wide ranging coverage of newer generation mobile telecommunication systems without necessarily needing to rely on the high data rates available in such systems. For example, a less complex device may be a tiny device equipped with sensors and a small battery capacity. Such a less complex device needs to transmit the sensor data at a typically infrequent and / or low data rate. Furthermore some devices may not include a power source may derive power for transmitting signals based on a received radio frequency carrier wave. Such devices may be referred to as “tags”. The disclosed technology relates to improvements in or relating to communication systems which include tags.

[0009] SUMMARY The present disclosure is defined by the claims.

[0010] According to a first aspect embodiments can provide a detection station for detecting signals from tags, the detection station comprising receiver circuitry configured to detect backscattered signals transmitted by one or more tags. The one or more tags comprise an antenna and circuitry connected to the antenna, and the control circuitry and the antenna are configured to backscatter radio frequency signals received from one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the tags. The detection station comprises transmitter circuitry configured to transmit signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with a controller station for communicating with the controller station for controlling the one or more carrier wave emitters to transmit carrier wave signals. The control circuitry is configured with the receiver circuitry and the transmitter station, to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the one or more carrier wave emitters, and to cooperate with the controller station to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags in response to the detected backscattered signals.

[0011] According to a second aspect embodiments can provide a controller station for controlling one or more carrier wave emitters in a communications system, the controller station comprising receiver circuitry configured to receive signals, transmitter circuitry configured to transmit signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with the one or more carrier wave emitters for controlling the one or more carrier wave emitters to transmit carrier wave signals to one or more tags. The control circuitry is configured with the transmitter and receiver circuitry and the controller circuitry to transmit control signals to the one or more carrier wave emitters to control transmission of radio frequency carrier wave signals to the one or more tags in response to backscattered signals.

[0012] Embodiments of the present technique can provide a communications system comprising one or more tags, a controller station, one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the one or more tags, and a detector station. The detector station is configured to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the carrier wave emitter, wherein the controller station is connected to the one or more carrier wave emitters via an interface and is configured to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags. In some examples, the controller station and the detection station are formed by the same device such as an infrastructure equipment of a wireless communications network. In other examples the controller station is formed from an infrastructure equipment and the detection station is formed from a communications device which communicates with the infrastructure equipment

[0013] In some examples, the detection station or the controller station may control the one or more carrier wave emitter in response to the backscattered signals detected from one or more of the tags. Accordingly an advantage can be provided by controlling the carrier wave emitters to reduce interference and reduce power consumption by adjusting transmission of the carrier wave signals in response to the detected backscattered signals so that a power of the carrier wave signals can be adjusted and this can be controlled to only be transmitted when one or more tags present.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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:

[0016] Figures 1A and IB schematically represent examples of communication systems in which tags are deployed within a coverage area of an infrastructure equipment (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 in accordance with an example embodiment;

[0017] Figure 2 is a schematic block diagram illustrating an example wireless communications network configured in accordance with a 5G or new radio (NR) 3 GPP standard according to example embodiments;

[0018] Figure 3 is a schematic block diagram illustrating in more detail a communications device (UE) and an infrastructure equipment (gNB) formed from components of the wireless communications network shown in Figure 2;

[0019] Figure 4 is a schematic block diagram illustrating an example of backscattering circuitry which may be in employed with example embodiments;

[0020] Figure 5 is a schematic illustration representing an example embodiment in which a signal backscattered from a carrier wave signal transmitted by an external carrier wave signal is detected according to one example;

[0021] Figure 6 is a schematic block diagram illustrating an arrangement in which a carrier wave emitter is controlled using an interface between an infrastructure equipment (gNB) and a communications device (UE) forming part of the carrier wave emitter;

[0022] Figure 7 is a schematic block diagram illustrating an arrangement in which an infrastructure equipment (gNB) forming a detection station transmits power control commands to a carrier wave emitter to control transmission of the carrier wave signal according to example embodiments;

[0023] Figure 8 is a schematic block diagram illustrating an example arrangement in which interference caused by a backscattered signal is controlled by an infrastructure equipment (gNB) forming part of a wireless communications network according to example embodiments;

[0024] Figure 9 is a schematic block diagram illustrating an example arrangement in which an infrastructure equipment (gNB) controls a power of a carrier wave signal transmitted by a carrier wave emitter to reduce interference caused by backscattered signal according to example embodiments; and

[0025] Figure 10 is a schematic representation of a deployment of tags in a geographical area in which tags can be identified by increasing the carrier wave signal power level II spatially multiplex tags according to example embodiments.

[0026] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] Ambient loT In release 19 of 3GPP (Rel-19), 3GPP will study Ambient loT [1] where a communications device (UE) is essentially a zero power UE. In Ambient loT, it is considered that the UE can harvest energy to power its communication with the gNB, for example, the energy can be harvested from solar or kinetic energy such as vibrations. Alternatively, the energy to power the device can come from incident RF energy, either directly from a base station (gNB) or from a carrier wave (CW) emitter. An example in which such devices which are powered by radio frequency energy derived from radio signals as a carrier wave transmitted by a carrier wave emitter (CWE) is shown in Figures 1A and IB, which consider different example configurations of a communication system according to example embodiments. Figures 1A and IB show a plurality of low-power 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 devices 1 are powered as a result of radio frequency energy received from an incident carrier wave (CW) 2 transmitted by the CWE 3. In a first example illustrated by Figure 1A, a base station 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 signal 2 transmitted by the CWE. In a second example, a detection station in the form of a UE 7 receives a backscattered signal 5 from the tags 1. The detection station or UE 7, then transmits an indication of the received backscattered signals 5, which were received from the tags 1, to the gNB 4 via a wireless access interface 8 formed between the gNB 4 and the UE 7. Therefore, according to example embodiments, a controller station (gNB 4) controls the carrier wave emitters 3 to transmit the carrier waves, and the backscattered signals are detected by detection station (UE) 7 and the detection station reports the detected backscattered signals to the controller station 4. 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.

[0028] 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.

[0029] As shown in Figures 1A and IB and in accordance with example embodiments, the gNB 4, which provides a wireless access interface within a cell represented by dashed line 12 controls the CWE 3 to transmit the CW 2 as will be explained below. The gNB 4 therefore has an interface 6 to the CWE 3. In some examples the CWE 3 is formed or controlled by a communications device or UE which operates with a wireless communications network of which the gNB 4 forms part. The gNB 4 can therefore control both a power and an activation of the CW transmitted by the CWE via the interface 6. In some examples therefore the interface 6 may be a Uu interface using 3 GPP terminology.

[0030] The CWE 3 can be a standalone device or can be part of another network node. In one example, the CWE is a UE, such as a legacy UE or smartphone. In this case, the UE can be controlled to send a suitable signal to act as a carrier wave signal. It is also possible for the AIoT device to transmit data in the uplink by backscattering another signal (for example the DL signal from the gNB). In some examples, such as the example of Figure IB, the backscattered signal 5 may be received by a separate detection station 7 or reader which does not form part of the gNB 4 and indeed in some examples whilst the CWE 3 are controlled in accordance with example embodiments, this may not form part of a wireless communications network and may be a stand-alone operation. However since example embodiments can operate within or in association with wireless communications networks, and architecture of a typical 5G or New Radio (NR) wireless communications network will be now be described with reference to Figures 2 and 3. As will be explained below, embodiments of the present technique aim to reduce interference to other devices including those operating with a wireless communications network.

[0031] In some examples the carrier wave emitter 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.

[0032] 5G New Radio (NR) Wireless Communications System

[0033] An example configuration of a wireless communications network which uses some of the terminology proposed for NR is shown in Figure 2. In Figure 2 a plurality of transmission and reception points (TRPs) 10 are connected to distributed control units (DUs) 41, 42 by a connection interface represented as a line 16. Each of the TRPs 10 is arranged to transmit and receive signals via a wireless access interface within a radio frequency bandwidth available to the wireless communications network. Thus, within a range for performing radio communications via the wireless access interface, each of the TRPs 10, forms a cell of the wireless communications network as represented by a dashed line 12. As such, wireless communications devices 14 which are within a radio communications range provided by the cells 12 can transmit and receive signals to and from the TRPs 10 via the wireless access interface. Each of the distributed units 41, 42 are connected to a central unit (CU) 40 (which may be referred to as a controlling node) via an interface 46. 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.

[0034] The elements of the wireless access network shown in Figure 2 may operate in a similar way to corresponding elements of an LTE network. It will be appreciated that operational aspects of the telecommunications network represented in Figure 2 and of other networks discussed herein in accordance with embodiments of the disclosure which are not specifically described (for example in relation to specific communication protocols and physical channels for communicating between different elements) may be implemented in accordance with any known techniques, for example according to currently used approaches for implementing such operational aspects of wireless telecommunications systems, e.g. in accordance with the relevant standards.

[0035] The TRPs 10 of Figure 2 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.

[0036] In terms of broad top-level functionality, the central unit 40 and associated DUs 41, 42 / TRPs 10 may be broadly considered to provide functionality corresponding to the base station 1 of Figure 1. The term network infrastructure equipment / access node may be used to encompass these elements and more conventional base station type elements of wireless telecommunications systems. Depending on the application at hand the responsibility for scheduling transmissions which are scheduled on the radio interface between the respective distributed units and the communications devices may lie with the CU 40, DUs 41, 42 and / or TRPs 10. Communications devices 14 are represented in Figure 2 within the coverage area of respective communication cells 12. These communications devices 14 may thus exchange signalling with the CU 40 via the TRP 10 associated with their respective communications cells 12.

[0037] It will further be appreciated that Figure 2 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.

[0038] A more detailed diagram of some of the components of the network shown in Figure 2 is provided by Figure 3. In Figure 3, a TRP 10 as shown in Figure 2 comprises, as a simplified representation, a wireless transmitter 30, a wireless receiver 32 and a controller or controlling processor 34 which 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 14 within a cell 12 formed by the TRP 10. As shown in Figure 3, an example UE 14 is shown to include a corresponding 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.

[0039] 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.

[0040] 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 the network interface 50 of the TRP 10 to the DU 42 and the Fl interface 46 from the DU 42 to the CU 40.

[0041] RF Incident Energy

[0042] As explained above with reference to the example shown in Figure 1, Ambient loT proposes to use energy received from a radio frequency carrier wave in order to power devices. An Ambient loT device could be powered by other ambient power sources, such as solar or thermal power. Harvesting energy based on the incident RF energy has several advantages and disadvantages.

[0043] An advantage is the RF energy is always available. Hence the Ambient loT device can always be awake while being powered from this energy. Furthermore a signal transmitted in the uplink form a tag can be backscattered using the incident radio frequency wave.

[0044] A disadvantage is the received power of the RF energy source is typically low. A receiver operating on such energy typically requires a power level of -30dBm to -20dBm for operation, which is not consistent with the low amounts of received power that are typically available directly from a base station. This required received power level sets a limit on the range (communication distance) supported by the AIoT system.

[0045] Another disadvantage is the transmission power level of a device that is powered by an RF energy source is typically very low. Such devices may operate based on backscattering technology, for example. The backscattered signal is created at the same carrier frequency as the incident RF energy. It is thus hard for the source of the RF energy (e.g. a gNB) to differentiate between the transmitted RF signal and the backscattered signal.

[0046] Another disadvantage is that, to reduce the power consumption of a receiver that operates on incident RF energy, a low power waveform / signaling scheme that is amenable to being decoded and received by a low power consumption receiver is typically required. For example, an on-off keying (OOK) signaling scheme may be used for such lower power communications. There are then issues of multiplexing this new signaling scheme with the currently supported orthogonal frequency-division multiplexing (OFDM) and DFT-s-OFDM waveforms.

[0047] Despite the above listed disadvantages, it is considered that Ambient loT based on RF incident energy is feasible. Hence, 3GPP have started a study item on Ambient loT technology [1] and collected some initial design targets, requirements, topologies, deployment scenarios etc in a technical report TR38.848 [2],

[0048] Backscattering Principle

[0049] A passive device can transmit in the 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.

[0050] Different from the conventional wireless device which actively generates its own signal, backscattering devices rely on reflecting a received signal to transmit data. The encoded data is modulated by varying the amplitude (ASK), phase (PSK), or frequency (FSK) of the signal to be reflected. More specifically, backscattering modulation is achieved by alternating between distinct load impedances of the antenna, with each impedance state leading to a unique characteristic of the reflected signal [4], Figure 4 illustrates a generic form of the backscattering circuitry including a matching network and an IC.

[0051] There are two aspects of power that are relevant to the Ambient loT device:

[0052] • Absorbed power. This is the power that is energy harvested and can be used to drive the circuits within the tag.

[0053] • Reflected power. This is the power that is reflected as a backscattered signal.

[0054] Given the antenna and load impedances denoted as Za= Ra+ jRaand Z„ = Rn+ jXn,n = 1,2, respectively, the reflection coefficient corresponding to each state is expressed as where * denotes the complex conjugate operation. Note that the figure shows the antenna impedanceaas Zant. Note that it is possible for the load impedance to vary between more than two states, while in this document we consider binary state switching for the sake of simplicity. Ideally, when the load impedance is set equal to the antenna impedance at a certain state, e.g., n = 1. Z, = Z , Ij = 1 holds and thus the received power is completely reflected by the device. Note that in practice, the reflection coefficient | Tn| depends on the manufacturing process and may vary within the range of (0,1).

[0055] The absorbed power can be calculated as m,n=F’avail Cl—i i l ) where Pavaildenotes the power delivered from the antenna when the load impedance perfectly matches with the antenna impedance. Note that in the literature, is defined as the power transmission coefficient [4,5], In fact, the power captured by the antenna will be split into two; one part is scattered back to the reader while another part is delivered to the tag. For the design of the reflection ratio, a trade-off needs to be considered to balance the need for both parts of the power.

[0056] Given PaVaii- the average power absorbed by the device can be calculated as

[0057] Where pn,n=i,2 denote the ratio of time duration for each impedance state; = p2holds if the probability of each impedance equals to the other (this also means same probability of Os and Is appeared in the encoded data if the backscattered signal uses a pure OOK waveform). Assuming that there are no antenna losses, the backscattered signal power is calculated as (considering ideal antenna).

[0058] CW Emitter

[0059] Example embodiments address the case that the signal from the tag that is backscattered. The carrier-wave emitter (or CW emitter / CWE) transmits a carrier wave signal (CWS) that can be used by the tag to backscatter a signal from. The tag may additionally harvest energy from the CWS or simply use the power from the CWS to power the circuitry in the tag (i.e. energy may not be stored by the tag but may be used for ongoing operations). The scenario is shown in Figure 5. Figure 5 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 4. 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.

[0060] The tag can be powered by non-RF energy sources, such as via solar power. The tag can also / alternatively be powered by an RF energy source. The RF energy source may be the same signal as the CW emitter (the CW signal may both power the tag and provide a signal that can be backscattered from).

[0061] The CW emitter devices may take the following forms:

[0062] • Base station. The base station (e.g. gNodeB) acts as the CW emitter. • Intermediate node. A reader may act as the CW emitter. The reader is a device that receives the backscattered signal, demodulates it and sends the result to the base station. The reader may also send downlink signals to the tag.

[0063] • Dedicated node. The CW emitter may be a dedicated node whose purpose is to provide a CW signal that can be backscattered from. The CW signal can also be used to power the tag, as discussed above.

[0064] The tag may receive sufficient power to decode downlink signalling, but not have sufficient power to transmit a backscattered signal in the UL (there is insufficient link budget in the uplink). In an example, the tag can decode the AIoT downlink based on ambient RF power, for example power that is received directly from the gNB.

[0065] Example embodiments provide control of CW emitters that are dedicated nodes. The dedicated node CW emitters can have the following characteristics:

[0066] • Deployed close to tags. For example, CW emitters can be installed in a “goods in” bay of a warehouse. Deploying the CW emitters close to the tags is good since the power that hits the backscattering device is relatively high, leading to a larger backscattered signal and improved coverage.

[0067] • Transmit a CW signal in licensed spectrum. By transmitting the CW signal in licensed spectrum, the backscattered signal is backscattered in the licensed spectrum.

[0068] • CW emitters may be deployed in either DL or UL spectrum. Note that in the 3GPP AIoT study item, deployment in UL spectrum is assumed.

[0069] The protocol for Ambient loT operation can be based on a command / response type of protocol. The detection station (which might be the gNodeB) sends a downlink command signal with a command to the tag. For example, the downlink command signal could indicate to the tag that it should respond with its identity (such as an identity number). The downlink command signal could indicate some further aspect of how the tag should respond. For example, the downlink command signal may indicate an amount of frequency shift that should be applied to the response signal, or may indicate a time at which the response signal should be transmitted. Based on the downlink command signal, the tag responds with a backscattered signal, where the backscattered signal is backscattered on the carrier wave signal.

[0070] Acronyms

[0071] We use the following acronyms:

[0072] CWS: Carrier wave signal. This is the signal or power that is sent by a carrier wave emitter in order to provide a signal from which the tag can send a backscattered signal.

[0073] CWE: carrier wave emitter. This is an entity that transmits a carrier wave signal. The CWE can be a standalone device or could be co-located with the reader.

[0074] A CW emitter that transmits power constantly will have the following problems: Excess power consumption. There is no point in transmitting when there are no tags in the vicinity that need to be powered up

[0075] CW emitters operating in UL spectrum create interference at the gNB (or reader) that needs to be controlled. The transmission from the CW emitter can interfere at the gNB with transmissions from either: o Tags (including tags that are illuminated by other CW emitters) o Legacy devices (such as smartphones) o UL transmissions in neighbouring cells

[0076] There is hence a need to control the CW emitters in a network that supports AIoT devices.

[0077] Embodiments of the present technique can provide a communications system comprising one or more tags comprising an antenna and circuitry connected to the antenna, the control circuitry and the antenna being configured to backscatter radio frequency signals, one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the one or more tags, and a detector station. The detector station is configured to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the carrier wave emitter. The detector station is connected to the one or more carrier wave emitters via an interface and is configured to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags.

[0078] In some examples, the detection station may control the one or more carrier wave emitter in response to the backscattered signals detected from one or more of the tags. Accordingly an advantage can be provided by controlling the carrier wave emitters to reduce interference and reduce power consumption by adjusting transmission of the carrier wave signals in response to the detected backscattered signals so that a power of the carrier wave signals can be adjusted and this can be controlled to only be transmitted when one or more tags are present.

[0079] The detection station may be a standalone reader or an infrastructure equipment (gNB). According to example embodiments a carrier wave emitter is controlled by the gNB or reader to turn on / off a carrier wave signal or can be controlled to vary a parameter of the carrier wave signal (e.g. the power of the carrier wave signal).

[0080] Embodiment A: CWE is connected to the gNB or reader

[0081] A connection to the gNB or reader allows the CWE to be controlled by the gNB, allowing the gNB to power control CWEs, turn CWEs on and off, and implement other functions according to aspects of this invention. The connection can be a logical or physical (including wireless) connection.

[0082] A.1 CWE is connected to the gNB.

[0083] In one example, the detector station may be an infrastructure equipment (gNB) forming part of a radio network of a wireless communications network. This allows the gNB to control the CWE directly. A.1.1 CWE has a UE function. The UE that is part of the CWE allows the gNB to communicate directly to the CWE, as shown in Figure 6. In Figure 6, a UE 76 forms part of the carrier wave emitter 3 and forms a connection 78 using a wireless access interface provided by the gNB 4.

[0084] As will be appreciated, a UE function is incorporated within a network entity. Other examples of a UE function being incorporated within a network entity include RIS, integrated access and backhaul (JAB) and network controlled repeaters (NCR). More details of IAB are disclosed in our copending European patent application EP21192674.6 the contents of which are incorporated by reference.

[0085] A.1.2 CWE connected by other backhaul. The CWE could be connected to the gNB by another backhaul link (other than the over the air gNB to UE link, Uu, discussed in A.1.1). The CWE could be connected to the internet and be controlled by the gNB via an internet connection. The CWE could be connected by WiFi, Ethernet or some other technology.

[0086] A.2 CWE is connected to the reader.

[0087] This allows the reader to control the CWE. This sort of connection is useful when the reader needs to control the transmissions from the tag, for example when the interference problem to be solved is the interference at the reader, or when the reader includes a scheduling function (where the reader can decide which tags to schedule and hence needs to control which tags are illuminated by the CWS).

[0088] Note: in the following embodiments, we generally assume that the CWE is controlled by the gNB, but embodiments are also applicable to control by the reader.

[0089] According to some example embodiments, a detection station may control some aspects of the CWE, such as the power of the CWE or the on / off status of the CWE. In other examples, when the detection station is a reader, the detection station can either communicate directly with the CWE to control the CWE’s operation or can communicate some desired aspect of the CWE operation to the gNB and the gNB can communicate with the CWE, where the gNB acts as a controller station. It will be appreciated that it is often advantageous for a controller station to control CWE operation (even when power levels are measured at a reader operating as a detection station), for example in the case that multiple readers (detection stations) control the same CWE. In this example, one detection station might consider that the CWE power should be reduced while another detection station considers that the power of the same CWE should be increased. A controller station (such as a gNB) can take a global view of the requests from the multiple reader detection stations and hence configure a CWE power that is appropriate to the multiple of the detection stations. For the sake of brevity, the description refers to a detection station communicating with a CWE, but a skilled artisan would understand that that communication can pass through another node, such as a gNodeB acting as a controller station, and that that other controller station might aggregate communications from the detection stations to determine an overall communication message that is sent to the CWE. Embodiment B. Power control. The power of the CWE is power controlled. The power of the CWS is increased or decreased depending on the power control command from the gNB, as shown in Figure 7. As shown in Figure 7, the gNB 4 as a detection station sends power control commands 80 via the interface to the carrier wave emitter 3. According to example embodiments the detector station (gNB 4) is configured to control a transmission power of carrier wave signals transmitted by the one or more carrier wave emitters 3.

[0090] B.l Based on power of received backscattered signal

[0091] The gNB receives the backscattered signal and measures the power of the received backscattered signal. Depending on the received power of the backscattered signal, the gNB controls the output power of the CWS transmitted by the CWE:

[0092] • Received power greater than required => “power down” signal sent to CWE

[0093] • Received power less than required => “power up” signal sent to CWE

[0094] The power control command can be in the form of a transmit power control (TPC) command or can more directly control the transmit power of the CWE (for example by sending a number indicating either the relative magnitude by which the CWS power should change or the absolute target power of the CWS).

[0095] Bl.l Power control based on received power of backscattered signal. The power control command is based on the received power of the backscattered signal.

[0096] Bl .1.1 Power control based on received power of backscattered signal of single tag. While the CWS may be used by multiple tags for backscattering, this embodiment only controls the power based on received power from a single tag. This approach is particularly applicable when only a single tag is interrogated at a time. It is more problematic when multiple tags backscatter on the CWS at the same time (e.g. via a frequency division multiplexing or code division multiplexing scheme).

[0097] Bl .1.2 Power control based on received power of backscattered signal of multiple tags. This approach is particularly applicable when the backscattered signal powers from different tags can be measured separately. When multiple tags backscatter on the same CWS, the power control command may be based on either:

[0098] • the aggregate backscattered signal power. This approach might be applicable when the goal is to minimize interference.

[0099] • the weakest received backscattered signal power from a tag of interest. This approach might be applicable when the goal is to attempt to receive a signal from a distant tag that is received at a low signal level. The received power of that tag’s signal could be increased by increasing the CWS power. • the strongest received backscattered signal power from a tag. This approach might be applicable when a large backscattered signal from one of the tags could distort the gNB receiver or exceed the dynamic range of the gNB receiver and hence desensitize the gNB receiver to lower power backscattered signals from other tags. The received power of that tag’s signal could be reduced by reducing the CWS power.

[0100] Bl .2 Power control based on interference caused by backscattered signal. The gNB can estimate the interference caused by the backscattered signal, for example by measuring the power of received harmonics of the received backscattered signal. The power control function would then power control the CWS such that interference received is less than a target.

[0101] It can be important to power control the backscattered transmission (via power control of the CWS) in the case that the spectrum is shared between AIoT tags and legacy devices, as shown in Figure 8. Figure 8 shows a backscattered signal 5 that is meant to be transmitted at a frequency f>. Since there is limited transmit filtering in the tag 1 and the tag’s electronic components are unsophisticated, the tag’s backscattered signal contains harmonic components, represented as a power spectrum 82 such as a harmonic component at a frequency fi. This harmonic component may interfere with the uplink transmission from a legacy device 84 (e.g. smartphone) that is scheduled to transmit at that frequency fi. Hence, it is beneficial to power control the CWS so as to minimize the interference with the smartphone’s UL transmission.

[0102] Bl .3 Power control based on presence of backscattered signal. The CWS can be used to power the tag (to provide RF incident power) as well as to provide a wave that can be used for backscattering. If there is insufficient power in the CWS to power the tag, the tag would not receive the DL command signal and would not backscatter anything.

[0103] Hence, if the gNB does not receive a backscattered signal from the tag and estimates that that backscattered signal was not present, the gNB instructs the CWE to increase the power of the CWS. This can be repeated until the CWE provides a CWS with sufficient power to power up the tag.

[0104] B.2 Based on power of received CWS at serving cell

[0105] The CWS will be received by the gNB in addition to the backscattered signal. Indeed, the CWS is likely to be the main component of the backscattered signal since the backscattered signal is carried on the CWS. Although the gNB may attempt to cancel the interference from the CWS via interference cancellation circuitry, there may still be residual interference from the CWS.

[0106] Hence, in this embodiment, the gNB measures the interference caused by the CWS and sends a power control command to the CWE based on that interference measurement. The goal is that the interference caused by the CWS at the gNB should fall below a threshold.

[0107] This embodiment is illustrated in Figure 9 where the CWS 2 provides a signal from which the tag 1 can backscatter a signal but the CWS is also received by the gNB 4. The gNB 4 then sends power control commands 80 to the CWE 3, based on the measured interference level caused by the CWS.

[0108] B.3 Based on power of received CWS at neighbour cell The interference caused by the CWS can be measured at a neighbour cell. The neighbour cell then sends a report to the serving cell of the interference level (or the excess interference above a tolerable amount) and the serving cell uses this information to send a power control command to the CWE. The report may be sent from the neighbour cell to serving cell over a backhaul interface such as X2.

[0109] B.4 Based on number of responding tags

[0110] The number of responding tags may depend on the CWS power. For example, if the CWS power is too low, few tags are energized and hence few tags respond with a backscattered signal. Alternatively, if the CWS power is too high, too many tags may respond with a backscattered signal.

[0111] It would be possible to query different tags in the deployment based on the power of the CWS: starting with a low CWS power, only tags close to the CWE would respond increasing the CWS power, further distant tags would respond

[0112] By changing the power of the CWS, the tags that respond could hence be controlled, from tags close to the CWE to tags distant from the CWE. As the power ramps up, tags that had previously responded could be prevented from responding at the higher power level, such that a tag does not respond to an interrogation multiple times.

[0113] Power controlling based on the number of responding tags may be useful when the gNB / reader is able to process backscattered signals from a limited number of tags at a time (for example due to multiplexing or processing constraints).

[0114] Figure 10 shows the spatial multiplexing of tags by changing the power level of transmissions. The figure shows a CWE and two tags, tagl and tag2. Tagl is located in a region close to the CWE, region A. Tag2 is located further away from the CWE in region B. The CWE is able to spatially multiplex the tags as follows:

[0115] • CWS is sent at a first low power level. This CWS is labelled CWS 1. Tagl (and other tags in region A) is able to backscatter based on this power level.

[0116] • The power level of the CWS is increased. The CWS can indicate those tags that have already responded and should not respond at this increased power level. Hence, tags in region B (such as tag2) respond and those tags in region A do not respond.

[0117] Hence the system is able to spatially multiplex the tags, because the tags respond at different times.

[0118] B.4.1. Tag does not respond for a certain time after it has responded previously

[0119] Once a tag has responded, it doesn’t respond for a time Ti. This allows other more distant tags to respond within that Ti time window. The CWE could increase the CWS power during this time window and the tags that had previously responded wouldn’t respond at this increased power level. B.4.2. Downlink command signal contains an ID and the tag doesn’t respond to the same ID for a period of time.

[0120] The downlink command signal can contain an ID, allowing the system to differentiate between downlink command signals. To interrogate multiple tags within an area, the gNB increases the CWS power stepwise, as per B.4.1. The use of multiple IDs avoids the potential latency issue of B.4. 1 by allowing a previously interrogated tag to be interrogated within the Ti time window by sending a downlink command signal with an updated ID.

[0121] B.4.3 Downlink command signal sends a list of tag IDs that shouldn’t respond

[0122] The list allows the gNB to stop devices that had previously responded at a lower power level from responding. When a CWS is sent at a higher power level, only UEs (e.g. more distant UEs) that are not contained within the list would respond.

[0123] This allows the gNB to increase the CWE power in a stepwise manner. At a low power level, Pi, tags close to the CWE (the “first set”) will respond. At the next higher power level, P2, the downlink command signal would indicate that tags in the first set should not respond. Hence, at the P2 power level, those tags in an annulus further away from the CWE will respond etc. In this manner, responses from the tags can be multiplexed, such that not all of the tags respond at the same time.

[0124] B.4.4 Power stepping used to locate the device

[0125] Note that embodiments where the power is increased in a stepwise manner can help in locating the tag. The gNB / reader would know that the tag is located within an area associated with a particular power level of the CWS . Knowing the relationship between the range of the CWS signal transmitted at a certain power level and the power level (e.g. via a path-loss equation), information on the position of the tag can be derived. Referring to Figure 10, the system can determine whether the tag is in region A or region B of the deployment. Further positioning measurements can help to further locate the tag. For example, the angle of arrival of a backscattered signal can further locate the tag within region A or region B.

[0126] B.4.5 CWS power threshold for response

[0127] Either the downlink command signal or the CWS signal indicate a power threshold that controls whether a tag responds.

[0128] B.4.5.1 CWS power threshold is a minimum

[0129] A tag responds if the CWS power is above a minimum value. This embodiment ensures that tags will only respond if their backscattered signal is likely to successfully reach the gNB (i.e. if the backscattered signal will have sufficient power to reach the gNB).

[0130] B.4.5.2 CWS power threshold is a maximum A tag responds if the CWS power is below a maximum value. This helps to spatially multiplex multiple tags. As such:

[0131] CWS is initially sent at a relatively low power and with a large maximum power threshold.

[0132] Only tags within region A of Figure 10 will receive the CWS and they will respond. o The backscattered signal may contain an indication of the measured CWS power level at the tag

[0133] CWS is sent at a higher power level and the power threshold is set below the power at which tags in region A receive CWS. The power threshold may be set based on the indication in the above bullet o Tags in region A do not respond to this CWS since their received power level is above the maximum power threshold o Tags in region B receive a sufficiently powerful CWS and their received power level is below the maximum power threshold (since they are further away from the CWE than tags in region A)

[0134] In this way, the system is able to get tags in different regions of the deployment to respond at different times, hence multiplexing the tag responses.

[0135] B.5 Additional CWE activated if received backscattered signal is too low

[0136] If insufficient power is received from the backscattered signal, additional CWEs can be activated to increase the CWS for backscattering. The tag would then send the backscattered signal on the aggregated CWS from all of the CWE. The tags may not be aware that they are sending a backscattered signal on an aggregated CWS - they just backscatter on the CWS, wherever it is from.

[0137] Embodiment C. Turning on and off CWE

[0138] CWE are turned on or off based on the presence of tags, on tag activity or on whether the gNB / reader is actively engaged in Ambient loT communications.

[0139] C.l. CWE are turned on and off based on gNB activity

[0140] When the gNB / reader needs to communicate with tags, the appropriate CWE are turned on, otherwise CWE can remain off.

[0141] For example, if the gNB wishes to communicate with tags in its deployment area, it turns CWE on within that deployment area. If the gNB is not communicating with tags, it turns the CWE off.

[0142] This saves on the power consumption of the CWE and reduces interference when CWE are not transmitting. C.2 CWE are turned on and off based on location

[0143] CWE are turned on and off based on tag location (or location in which the gNB wants to communicate with tags - the gNB may not know the tag location and so can only turn on CWE in locations where it thinks the tag may be located).

[0144] C.2.1 Potential tag location is signalled by another device

[0145] Another device containing a UE function can signal to the gNB the potential location of tags. The gNB can then use that information to decide which CWE to turn on.

[0146] For example, a forklift truck may be carrying a pallet of parcels, where the parcels carry tags. A UE on the forklift can indicate the location of the forklift to the gNB. The gNB can then activate CWE in the vicinity of the forklift in order to read the inventory of the parcels.

[0147] In another example, a reader wishes to determine the inventory in a certain area of a warehouse. The reader can indicate its location to the gNB and the gNB can turn on CWE in the vicinity of the reader.

[0148] C.3 CWE are turned on and off based on measurements of backscattered signal

[0149] The CWE that yields the strongest backscattered signal from a tag can be used for further communications with that tag and other CWE can be turned off when communicating with that tag.

[0150] C.3.1 Measurement at gNB

[0151] The backscattered signal is measured at the gNB. This allows for direct control of the CWE (either turning it on / off or power controlling the CWE).

[0152] The CWS from the different CWE may contain an identifying signal, such as a CDMA sequence or an offset of a cyclic shift of a signal carried by the CWS. Measurements made on this identifying signal would allow the gNB to choose a preferred CWE.

[0153] C.3.2 Measurement at CWE

[0154] The backscattered signal is measured at the CWE. The CWE can then either: determine whether the backscattered signal is sufficient. If it is insufficient, the CWE can conclude that it is not an appropriate CWE for sending a CWS to that tag. Alternatively, the CWE can power control itself directly until the backscattered signal level is at the target level. The target level can be set by the CWE or signalled to the CWE by the gNB.

[0155] Send reports of the backscattered signal strength to the gNB. The gNB can then choose an appropriate CWE for powering / illuminating the tag.

[0156] C.4 Tag in semi-fixed location The tag may be in a known location. In this case, a CWE can be associated with that tag and the CWE is only turned on when the gNB wishes to communicate with that tag.

[0157] In an example, the tag contains a sensor and is fixed to a wall. The tag location is known. If the system wants to know the sensor reading, the CWE close to that tag can be turned on.

[0158] In another example, a parcel with an attached tag is put in a known location in a warehouse. When the parcel is to be retrieved, the gNB can attempt to communicate with that tag by first activating the CWE close to that tag. If the tag is not found in the expected location, other CWEs can be turned on in order to look for the tag.

[0159] C.5 Round robin activation of CWE

[0160] A large warehouse may contain multiple CWE (for example, the CWE could be deployed in a grid across the warehouse). In order to read the tags in the warehouse, the CWE within the warehouse can be turned on and off in a round robin manner. This scheduling strategy allows CWE to be turned off (to save power and reduce interference) and provides a multiplexing function (the number of tags responding to the gNB can be controlled by controlling the CWE that are activated).

[0161] C.6 Wake up signalling from tag

[0162] Some tags can harvest and store energy. Some of these tags have an active transmitter. Some tags have an active transmitter in addition to a backscattering transmitter. Backscattering is not required for active transmission. The energy storage capacity of the tag may be limited.

[0163] In this embodiment, the tag sends a wake up signal via its active transmitter. The wake up signal can be transmitted for a short period of time using a low signal power, since only a few bits are carried by the wake-up signalling.

[0164] C.6.1 Tag sends wake up signal if CWS is insufficient

[0165] The tag only sends the wake up signalling if it determines that there is either no CWS, or that the CWS power is insufficient for successfully backscattering a signal.

[0166] Hence, the tag uses backscattering communication in preference to active communication. Active communication is used to transmit wake-up signalling that allows the tag to use backscattering communication in the future.

[0167] C.6.2 CWE receives wake up signalling

[0168] A CWE that receives the wake-up signalling turns on, allowing the tag to continue its communications using backscattering.

[0169] A CWE that receives wake-up signalling can indicate this to the gNB. The gNB can then decide whether to turn the CWE on. This maintains network control of the CWEs (and hence control of power consumption and interference). C.6.3 gNB receives wake up signalling

[0170] A gNB receives the wake-up signalling and then turns on a CWE in the area of the tag. The gNB may know the appropriate CWE by either: estimating the tag location based on measurements of the wake-up signal received from the tag knowledge of the tag location (for example in the case of a tag connected to a fixed sensor) the wake-up signalling includes an indication of the tag location or an indication of the preferred CWE (for example, the CWE that the tag used previously for backscattering communication).

[0171] Alternatively, the reader can receive the wake-up signalling. It can then send that to the gNB or turn a CWE on directly.

[0172] Embodiment D: CWE only transmit CWS when there is potentially UL traffic

[0173] The CWE only transmits CWS when there is potentially UL traffic.

[0174] D.l TDD frame structure

[0175] In this embodiment, the Ambient loT protocol operates according to a TDD frame structure. The CWE is made aware of the frame structure (which slots are UL and which are DL). For example, the CWE can be configured with the TDD frame structure. Alternatively, the CWE can learn / decode the frame structure by: listening for which slots are DL and which are UL. The CWE can assume that this slot / frame structure will continue into the future decode system information transmitted by the gNB. This can be a form of system information sent to the tags or can be system information that is sent to a cell that contains both tags and legacy devices (smartphones etc)

[0176] In this embodiment, the CWE turns on during UL portions of the TDD frame structure.

[0177] D.2 CWE monitors DL command signal

[0178] The CWE monitors the DL command signals from the gNB. The CWE can then determine from the DL command signals when a response is expected from tags. The CWE can then turn itself on and off, as appropriate.

[0179] D.2.1 DL command signal includes CWE identity

[0180] The DL command signal includes the CWE identity. The CWE reads the DL command signal. The CWE turns on or off in response to the command sent in the DL command signal. D.3 CWE monitors direct signalling from gNB

[0181] The gNB can transmit signals directly to the CWE to control when it turns on and off in parallel to communicating with the tag. The gNB can then control the CWE to send a CWS at the appropriate time for the tag to send information in the UL.

[0182] Communication protocol: the communication between the interrogator / reader and the tag may obey the following steps:

[0183] • Step 1 - the reader / gNB transmits to the tag a DL command signal.

[0184] • Step 2 - the tag receives and then processes the DL command signal; at the same time, the CWE is told to transmit CWS at the next step.

[0185] • Step 3 - the external CWE transmits the unmodulated carrier wave to the tag for it to backscatter the response to the reader.

[0186] • Step 4 - the reader successfully receives the tag’s response. An acknowledgement might be sent to the tag. A separate acknowledgement might be sent to the CWE (or the CWE can read the acknowledgement sent to the tag). This acknowledgement can indicate to the CWE that it can turn off.

[0187] Further example embodiments of the present technique are defined in the following numbered claims:

[0188] Paragraph 1. A controller station for controlling one or more carrier wave emitters in a communications system, the controller station comprising receiver circuitry configured to receive signals, transmitter circuitry configured to transmit signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with the one or more carrier wave emitters for controlling the one or more carrier wave emitters to transmit carrier wave signals to one or more tags, wherein the control circuitry is configured with the transmitter circuitry and the controller circuitry to transmit control signals to the one or more carrier wave emitters to control transmission of radio frequency carrier wave signals to the one or more tags in response to backscattered signals detected by a detector station.

[0189] Paragraph 2. A controller station of paragraph 1, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network. Paragraph 3. A controller station of paragraph 1, wherein the controller station is an infrastructure equipment of a radio network part of a wireless communications network and the transmitter circuitry is configured to transmit signals to communications devices via a wireless access interface provided by a wireless communications network and the receiver circuitry is configured to receive signals from the communications devices transmitted via the wireless access interface, and the interface with the controller station is formed by the wireless access interface, and the detection station is a wireless communications device which detects the backscattered signals and the controller station receives an indication of the backscattered signals received from the communications device transmitted via the wireless access interface.

[0190] Paragraph 4. A controller station of paragraph 1, wherein the interface with the one or more carrier wave emitters is formed by a wireless access interface provided by an infrastructure equipment and a communications device which includes transceiver circuitry configured to transmit and to receive radio signals via the wireless access interface provided by the wireless communications network, the communications device forming part of the one or more carrier wave emitters, the interface of the controller station formed by the infrastructure equipment uses the wireless access interface of the wireless communications network.

[0191] Paragraph 5. A controller station of any of paragraphs 1 to 4, wherein the carrier wave emitter forms part of the controller station.

[0192] Paragraph 6. A controller station of any of paragraphs 1 to 5, wherein the controller circuitry with the transmitter circuitry are configured to control a transmission power of carrier wave signals transmitted by the one or more carrier wave emitters, in response to a determined power of the detected backscattered signals.

[0193] Paragraph 7. A controller station of paragraph 6, wherein the controller circuitry with the receiver circuitry are configured to receive an indication of the determine power of the received backscattered signals from a detection device, to determine the transmission power of carrier wave signals based on the received indication of the determined power of the received backscattered signals to control the transmission power of the carrier wave signal transmitted by the one or more carrier wave emitters in accordance with the determined power of the received backscattered signals.

[0194] Paragraph 8. A controller station of paragraph 6, wherein the controller circuitry with the receiver circuitry are configured to receive commands for controlling a transmission power of the carrier wave signal by the one or more carrier wave emitters, and to control the transmission power of the carrier wave signal transmitted by the one or more carrier wave emitters in accordance with the received command.

[0195] Paragraph 9. A controller station of paragraph 7 or 8, wherein the controller station is configured to control the transmission power of carrier wave signals to effect a minimum received power level of the backscattered signal whilst reducing the transmission power of the carrier wave signal.

[0196] Paragraph 10. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the transmitter circuitry is configured to communicate a power control command to the one or more carrier wave emitters to control the transmission power of carrier wave signals, the power control command indicating whether the transmission power of the carrier wave signal should increase or decrease in accordance with the determined received power of the backscattered signal and a reception power target.

[0197] Paragraph 11. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on an aggregate of the determined power of the received backscattered signals from the plurality of the tags. Paragraph 12. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a lowest of the determined power of the received backscattered signals from the plurality of the tags.

[0198] Paragraph 13. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine a power of a backscattered signal received from a plurality of the tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a highest of the determined power of the received backscattered signals from the plurality of the tags.

[0199] Paragraph 14. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine from the received backscattered signals an amount of interference which is likely to be caused to other devices, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce interference which may be caused to the other devices by the backscattered signals.

[0200] Paragraph 15. A controller station of paragraph 14, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the interference comprises at least part of the backscattered signals which may interfere with uplink signals received by the infrastructure equipment from other communications devices communicating data via the wireless communications network.

[0201] Paragraph 16. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to transmit the carrier wave signal at a first power level, and to control the transmission power of carrier wave signals by increasing the transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters until an indication is received that one or more of the backscattered signals can be detected.

[0202] Paragraph 17. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to detect interference caused by the carrier wave signals when receiving the backscattered signals, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce a power of the detected interference by the carrier wave signals.

[0203] Paragraph 18. A controller station of any of paragraphs 6 to 9, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the controller circuitry with the receiver and transmitter circuitry are configured to receive an indication of interference caused by the carrier wave signals detected by another infrastructure equipment of the radio network of a neighbouring cell, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in response to the indication of the interference to the neighbouring cell. Paragraph 19. A controller station of any of paragraphs 6 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level, to identify one or more of the tags in a first category from which the backscattered signals can be received with the power of the first carrier wave signal at the first power level, to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level, which is greater than the first power level, to identify one or more of the tags in a second category from which the backscattered signals can be received with the second power of the second carrier wave signal at the second power level and for which the backscattered signal were not received with the power of the first carrier wave signal at the first power level, and to control the transmission power of the carrier wave signal with respect to the first power level and the second power level to receive the backscattered signals from the tags in the first category and the second category.

[0204] Paragraph 20. A controller station of paragraph 19, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals after transmitting a backscattered signal for a duration which is equal to or greater than a time for the carrier wave emitters to transmit the carrier wave signal at the second power level, so that one or more tags in the second category can be detected with the carrier wave signals transmitted at the second power level from one or more tags in the first category while the one or more tags in the first category are not transmitting.

[0205] Paragraph 21. A controller station of paragraph 19, wherein the first carrier wave signal includes a first identifier and the second carrier wave signal includes a second identifier, and the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals in response to the second carrier wave signal identified by the second identifier if they have transmitted a backscattered signal in response to the first carrier wave signal identified by the first identifier, and to transmit backscattered signals in response to the second carrier wave signal in the case that it is identified by the second identifier.

[0206] Paragraph 22. A controller station of paragraph 19, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and are configured with an identifier, and wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit a first downlink command to the one or more tags, and to control the one or more emitters to transmit a first carrier wave signal, to transmit a second downlink command to the one or more tags, the downlink command including an indication of the one or more identifiers of the first set which should not transmit backscattered signals in response to a second carrier wave signals, and, to transmit an indication to the one or more carrier wave emitters to control the transmission of the second carrier wave signal transmitted by the one or more carrier wave emitters, and to receive an indication of detect backscattered signals of the one or more tags that are not in the first set in response to the second carrier wave signal.

[0207] Paragraph 23. A controller station of paragraph 22, wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit a second downlink command to the one or more tags, the second downlink command identifying one or more of the tags of a second set from which the backscattered signals should be transmitted in response to a second carrier wave signal, which one or more tags of the second set have an identifier identified by the second downlink command, to control the transmission of a second carrier wave signal transmitted by the one or more carrier wave emitters to include a second identifier, and to detect in response to the second carrier wave signal the backscattered signals of one or more of the tags in the second set.

[0208] Paragraph 24. A controller station of paragraph 23, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission of the first carrier wave signal transmitted with a first power, and to control the transmission of the second carrier wave signal transmitted with a second power greater than the first power.

[0209] Paragraph 25. A controller station of paragraph 24, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine a location of one or more tags in the first set and the second set based on the first power and the second power and an angle of arrival of the backscattered signals received from each of the one or more tags in the first set.

[0210] Paragraph 26. A controller station of any of paragraphs 6 to 9, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit an indication of a power threshold of a received carrier wave signal, below which the one or more tags should not transmit the backscattered signal from the received carrier wave signal, and the one or more tags are configured in response to the received carrier wave signal, to determine whether a power of the received carrier wave signal is above the power threshold, and if above the power threshold to transmit the backscattered signal, and if below the power threshold to not transmit the backscattered signal.

[0211] Paragraph 27. A controller station of paragraph 26, wherein the indication of the power threshold is indicated in a downlink command transmitted by the detector station.

[0212] Paragraph 28. A controller station of paragraph 26, wherein the indication of the power threshold is indicated in the carrier wave signal transmitted by the carrier wave emitter. Paragraph 29. A controller station of paragraph 26, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit the backscattered signal if a power of the received carrier wave signal is below a maximum threshold, and wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit a first downlink command to the one or more tags indicating a first maximum power threshold, to control the transmission power of a first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level, to identify one or more of the tags in a first category from backscattered signals received with the power of the first carrier wave signal at the first power level, and to receive an indication of a measured power of the first carrier wave signal, to transmit a second downlink command to the one or more tags indicating a second maximum power threshold, which is below the measured power of the first carrier wave signal, to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level higher than the first power level.

[0213] Paragraph 30. A controller station of paragraph 26, wherein the controller circuitry with the receiver and transmitter circuitry are configured to select one or more of a plurality of the carrier wave emitters to transmit the carrier wave signals, to control the selected one or more of the carrier wave emitters to transmit the carrier wave signals, to determine a power of the received backscattered signals, and if a power of the received backscattered signals is below a predetermined threshold, to select one or more others of the plurality of carrier wave emitters to transmit the carrier wave signals, and to control the selected one or more other carrier wave emitters to transmit the carrier wave signals.

[0214] Paragraph 31. A controller station of any of paragraphs 3 to 9, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the one or more carrier wave emitters selectively to be turned on to transmit the radio frequency carrier wave signals to the one or more tags or turned off and not to transmit the radio frequency carrier wave signals to the one or more tags.

[0215] Paragraph 32. A controller station of paragraph 31 , wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine, based on whether one or more tags are present in a deployment area of the detector station, and if the one or more tags are present in the deployment area, selectively to turn on the carrier wave emitters, and otherwise to turn off the carrier wave emitters.

[0216] Paragraph 33. A controller station of paragraph 31 , wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine a location of the one or more tags, and based on a location of the one or more tags with respect to a location of a detector station, selectively to turn on or off the carrier wave emitters, based on the location of the one or more tags, to receive backscattered signals at the location of the detector station.

[0217] Paragraph 34. A controller station of paragraph 31, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the controller circuitry with the receiver and transmitter circuitry are configured to receive an indication of a location of the one or more tags from another communications device configure to communicate via the wireless access interface of the wireless communications network.

[0218] Paragraph 35. A controller station of paragraph 31 , wherein the controller circuitry with the receiver and transmitter circuitry are configured based on a location of the one or more carrier wave emitters and a determined power with which the received backscattered signals are received from one or more tags, selectively to turn on one or more carrier wave emitters, which result in a highest power of the received backscattered signals, and otherwise to turn off the other carrier wave emitters.

[0219] Paragraph 36. A controller station of paragraph 35, wherein the controller station is configured to receive an indication of measured power with which the received backscattered signals are received by a detection station from one or more tags for each of the one or more carrier wave emitters, and selectively to turn on the carrier wave emitter for which the power of the received backscattered signal is the highest.

[0220] Paragraph 37. A controller station of paragraph 36, wherein the carrier wave signal includes an identifying signal from which the backscattered signal with the highest power can be identified. Paragraph 38. A controller station of paragraph 35, wherein the controller station is configured to receive an indication of a measured power with which the received backscattered signals are received from one or more tags, and selectively to turn on the carrier wave emitter based on the power of the received backscattered signal, and to turn off the other carrier wave emitters.

[0221] Paragraph 39. A controller station of paragraph 31, wherein the controller station is configured to receive an indication of a measured power with which the received backscattered signals are received from one or more tags, and to increase a power of the carrier wave signal transmitted by the carrier wave emitter based on the power of the received backscattered signal, until a measured power of the received back scattered signal is above a minimum.

[0222] Paragraph 40. A controller station of paragraph 35, wherein a location of the one or more tags is known to the controller station, and the detector station is configured to turn on the one or more carrier wave emitters depending on a location of the one or more tags.

[0223] Paragraph 41. A controller station of paragraph 35, wherein the controller circuitry with the receiver and transmitter circuitry are configured selectively to turn on each of the carrier wave emitters in turn in accordance with a predetermined schedule.

[0224] Paragraph 42. A controller station in any of paragraphs 1 to 41, wherein the one or more tags include circuitry to transmit a wake up signal, and each of the one or more tags is configured to determine that it has not received the carrier wave signal for a predetermined time or that a power of the carrier wave signal detected by the tag is below a predetermined threshold, and in response to the carrier wave signal not being detected or detected with a power below the predetermined threshold to the transmit the wake up signal.

[0225] Paragraph 43. A controller station of paragraph 42, wherein the controller station is configured to detect the wake up signal, and in response to detecting the wakeup signal from the one or more tags, to control the one or more carrier wave emitters to transmit the carrier wave signal. Paragraph 44. A controller station of paragraph 43, wherein the carrier wave signal is transmitted in a location of the tag from which the wake up signal was received.

[0226] Paragraph 45. A controller station of paragraph 44, wherein the carrier wave signal is transmitted with an increased power.

[0227] Paragraph 46. A controller station of any of paragraphs 1 to 45, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, the infrastructure equipment being configured to provide a wireless access interface with a time division duplex, TDD, frame structure and the one or more carrier wave emitters are configured to transmit the carrier wave signal on uplink communications resources of the TDD frame structure, so that the backscattered signals are received on the uplink communications resources. Paragraph 47. A controller station of paragraph 46, wherein the one or more carrier wave emitters detect the TDD frame structure by monitoring signals transmitted or received by the infrastructure equipment.

[0228] Paragraph 48. A controller station of paragraph 46, wherein the one or more carrier wave emitters receive an indication of the TDD frame structure from the interface with the infrastructure equipment.

[0229] Paragraph 49. A controller station of paragraph 46, wherein the one or more carrier wave emitters determine the TDD frame structure by receiving an indication from system information broadcast by the infrastructure equipment.

[0230] Paragraph 50. A controller station of paragraph 46, wherein the one or more carrier wave emitters monitor downlink command signals transmitted by the infrastructure equipment, and based on the monitored downlink command signals determine when the carrier wave emitter should turn on to transmit the carrier wave signal and turn off not to transmit.

[0231] Paragraph 51. A method of operating a controller station in a communications system comprising transmitting control signals to one or more carrier wave emitters to control transmission of radio frequency carrier wave signals to one or more tags in response to backscattered signals detected by a detector station, the control signals being transmitted via an interface with the one or more carrier wave emitters for controlling the one or more carrier wave emitters to transmit carrier wave signals to one or more tags.

[0232] Paragraph 52. A detection station for operating with one or more tags, the detection station comprising receiver circuitry configured to detect signals, including backscattered signals transmitted by one or more tags, the one or more tags comprising an antenna and circuitry connected to the antenna, the control circuitry and the antenna being configured to backscatter radio frequency signals received from one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the tags, transmitter circuitry configured to transmit signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with a controller station for communicating with the controller station, for controlling one or more carrier wave emitters to transmit carrier wave signals, wherein the control circuitry is configured with the receiver circuitry and the transmitter circuitry, to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the one or more carrier wave emitters, and to cooperate with the controller station to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags in response to the detected backscattered signals.

[0233] Paragraph 53. A detection station of paragraph 52, wherein the detector station is a reader for reading the backscattered signals from the one or more tags.

[0234] Paragraph 54. A detection station of paragraph 52 or 53, wherein the detector station is a communications device and the transmitter circuitry is configured to transmit signals via a wireless access interface provided by a wireless communications network and the receiver circuitry is configured to receive signals transmitted via the wireless access interface, and the interface with the controller station is formed by the wireless access interface.

[0235] Paragraph 55. A detection station of paragraph 52, wherein the controller circuitry with the receiver circuitry are configured to determine a power of a backscattered signal received from one or the tags, and to transmit an indication of the determined received backscattered power to the controller station for the controller station to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in accordance with the determined power of the received backscattered signal from the tag.

[0236] Paragraph 56. A detection station of paragraph 52, wherein the controller circuitry with the receiver circuitry are configured to determine a power of a backscattered signal received from one or the tags, and to transmit a command signal to the controller to control the one or more carrier wave emitters based on the determined received backscattered power for the controller station to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in accordance with the determined power of the received backscattered signal from the tag.

[0237] Paragraph 57. A detection station of paragraph 55 or 56, wherein the detector station is configured to control the transmission power of carrier wave signals to effect a minimum received power level of the backscattered signal whilst reducing the transmission power of the carrier wave signal.

[0238] Paragraph 58. A detection station of any of paragraphs 54 to 57, wherein the controller station is an infrastructure equipment forming part of a radio network of the wireless communications network.

[0239] Paragraph 59. A method of operating a detection station in a communications system, comprising detecting signals backscattered from one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by one or more carrier wave emitters, the one or more tags comprising an antenna and circuitry connected to the antenna, the control circuitry and the antenna being configured to backscatter radio frequency signals received from one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the tags, and cooperating with a controller station to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags in response to the detected backscattered signals.

[0240] Paragraph 60. A carrier wave emitter, the carrier wave emitter comprises transmitter circuitry configured to transmit a carrier wave signal to one or more tags, to be detect backscattered by the one or more tags, the one or more tags configured to backscatter radio frequency signals received from carrier wave emitters, receiver circuitry configured to receive signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with a detection station for receiving control commands to from the detection station, wherein the control commands received from the detector station to control the carrier wave emitter to transmit the radio frequency carrier wave signals to the one or more tags. Paragraph 61. A communications system comprising one or more tags comprising an antenna and circuitry connected to the antenna, the control circuitry and the antenna being configured to backscatter radio frequency signals, one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the tags, a detector station configured to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the carrier wave emitter, and a controller station connected to the one or more carrier wave emitters via an interface and configured to cooperate with the detector station to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags in response to the detected backscattered signals.

[0241] Paragraph 62. A communications system of paragraph 61, wherein the detector station is a reader for detecting the backscattered signals from the one or more tags and the reader includes an interface with the controller station for indicating the detected backscattered signals. Paragraph 63. A communications system of paragraph 62, wherein the detector station is a communications device configured to communicate via a wireless access interface provided by a wireless communications network, and the controller station is an infrastructure equipment forming part of a radio network of the wireless communications network and the interface between the controller station and the detector station is formed by the wireless access interface. Paragraph 64. A communications system of paragraph 61, wherein the controller station and the detector station are combined and form part of an infrastructure equipment forming part of a radio network of a wireless communications network.

[0242] Paragraph 65. A communications system of paragraph 64, one or more of the carrier wave emitters comprises a communications device, the communications device including transceiver circuitry configured to transmit and to receive radio signals via a wireless access interface provided by the wireless communications network, the communications device providing the interface with the infrastructure equipment forming the detector station by using the wireless access interface of the wireless communications network.

[0243] Paragraph 66. A communications system of paragraph 64, comprising Integrated Access and Backhaul network equipment and the interface between the one or more carrier wave emitters and the infrastructure equipment forming the detector station is provided by the Integrated Access and Backhaul network.

[0244] Paragraph 67. A communications system of paragraph 62, wherein the carrier wave emitter forms part of the detection station or the controller station.

[0245] Paragraph 68. A communications system of any of paragraphs 61 to 67, wherein the detector station is configured to determine a power of the received backscattered signals, and to cooperate with the controller station to control a transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in accordance with the determined received transmission power of the backscattered signals.

[0246] Paragraph 69. A communications system of paragraph 68, wherein the detector station is configured to determine a power of the received backscattered signals, and to transmit an indication of the determined power of the received backscattered signals to the controller station for the controller station to control a transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters. Paragraph 70. A communications system of paragraph 69, wherein the communications device operating the detector station is configured to transmit the determined power of the received backscattered signals, and to transmit the indication of the determined power of the received backscattered signal to an infrastructure equipment operating as the controller station for controlling a transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters.

[0247] Paragraph 71. A communications system of paragraph 68, wherein the detector station is configured to determine a power of the received backscattered signals, to determine a power with which the carrier wave signal should be transmitted in response to the determined power of the received backscattered signals and to transmit a control command to the controller station for the controller station to transmit to the one or more carrier wave emitters to control a transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters.

[0248] Paragraph 72. A communications system of paragraph 71, wherein a communications device operating as the detector station is configured to determine the transmission power of carrier wave signals, which should be transmitted by the one or more carrier wave emitters, and to communicate a control command to the infrastructure equipment operating as the controller station for communication to the one or more carrier wave emitters to control the carrier wave emitter to transmit with the determined transmission power

[0249] Paragraph 73. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to control the transmission power of carrier wave signals to effect a minimum received power level of the backscattered signal whilst reducing the transmission power of the carrier wave signal.

[0250] Paragraph 74. A communications system of any of paragraphs 68 to 73, wherein the detector station and the controller station are configured to communicate a power control command to the one or more carrier wave emitters to control the transmission power of carrier wave signals, the power control command indicating whether the transmission power of the carrier wave signal should increase or decrease in accordance with the determined received power of the backscattered signal and a reception power target.

[0251] Paragraph 75. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to determine a power of a backscattered signal received from a plurality of the tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on an aggregate of the determined power of the received backscattered signals from the plurality of the tags.

[0252] Paragraph 76. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to determine a power of a backscattered signal received from a plurality of the tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a lowest of the determined powers of the received backscattered signals from the plurality of the tags.

[0253] Paragraph 77. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to determine a power of a backscattered signal received from a plurality of the tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a highest of the determined powers of the received backscattered signals from the plurality of the tags. Paragraph 78. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to determine from the received backscattered signals an amount of interference which is likely to be caused to other devices, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce interference which may be caused to the other devices by the backscattered signals. Paragraph 79. A communications system of paragraph 68, wherein one of the detector station and the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the interference comprises at least part of the backscattered signals which may interfere with uplink signals received by the infrastructure equipment from other communications devices communicating data via the wireless communications network.

[0254] Paragraph 80. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to transmit the carrier wave signal at a first power level, to determine whether one or more backscattered signals are received from the one or more tags, and to control the transmission power of carrier wave signals by increasing the transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters until one or more of the backscattered signals can be detected.

[0255] Paragraph 81. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to detect interference caused by the carrier wave signals when receiving the backscattered signals, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce a power of the detected interference by the carrier wave signals.

[0256] Paragraph 82. A communications system of any of paragraphs 68 to 72, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the detector station and the controller station are configured to receive an indication of interference caused by the carrier wave signals detected by another infrastructure equipment of the radio network of a neighbouring cell, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in response to the indication of the interference to the neighbouring cell. Paragraph 83. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to control the transmission power of a first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level, to identify one or more of the tags in a first category from which the backscattered signals can be received with the power of the first carrier wave signal at the first power level, to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level, which is greater than the first power level, to identify one or more of the tags in a second category from which the backscattered signals can be received with the second power of the second carrier wave signal at the second power level, which one or more tags in the second category from which the backscattered signals were not received with the power of the first carrier wave signal at the first power level, and to control the transmission power of the carrier wave signal with respect to the first power level and the second power level to receive the backscattered signals from the tags in the first category and the second category.

[0257] Paragraph 84. A communication system of paragraph 83, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals after transmitting a backscattered signal for a duration which is equal to or greater than a time for the carrier wave emitters to transmit the carrier wave signal at the second power level, so that one or more tags in the second category can be detected with the carrier wave signals transmitted at the second power level from one or more tags in the first category while the one or more tags in the first category are not transmitting.

[0258] Paragraph 85. A communication system of paragraph 83, wherein the first carrier wave signal includes a first identifier and the second carrier wave signal includes a second identifier, and the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals in response to the second carrier wave signal if they have transmitted a backscattered signal in response to the carrier wave signal identified by the first identifier, and to transmit backscattered signals in response to the second wave signal in the case that it is identified by the second identifier.

[0259] Paragraph 86. A communication system of paragraph 83, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and are configured with an identifier, and wherein the detector station and the controller station are configured to transmit a first downlink command to the one or more tags, a first carrier wave signal transmitted by the one or more carrier wave emitters, to receive from the one or more tags backscattered signals containing an identifier identifying each of the one or more tags of the first set, to transmit a second downlink command to the one or more tags, the downlink command including an indication of the one or more identifiers of the first set which should not transmit backscattered signals in response to a second carrier wave signals, and to transmit an indication to the one or more carrier wave emitters to control the transmission of a second carrier wave signal transmitted by the one or more carrier wave emitters, and to detect in response to the second carrier wave signal the backscattered signals of one or more of the tags that are not in the first set.

[0260] Paragraph 87. A communication system of paragraph 83, wherein the detector station and the controller station are configured to control the transmission of the first carrier wave signal transmitted with a first power, and to control the transmission of the second carrier wave signal transmitted with a second power greater than the first power.

[0261] Paragraph 88. A communication system of paragraph 87, wherein the detector station and the controller station are configured to determine a location of one or more tags in the first set and the second set based on the first power and the second power and an angle of arrival of the backscattered signals received from each of the one or more tags in the first set.

[0262] Paragraph 89. A communications system of any of paragraphs 68 to 72, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and wherein the detector station and the controller station are configured to transmit an indication of a power threshold of a received carrier wave signal, below which the one or more tags should not transmit the backscattered signal from the received carrier wave signal, and the one or more tags are configured in response to the received carrier wave signal, to determine whether a power of the received carrier wave signal is above the power threshold, and if above the power threshold to transmit the backscattered signal, and if below the power threshold to not transmit the backscattered signal.

[0263] Paragraph 90. A communications system of paragraph 89, wherein the indication of the power threshold is indicated in a downlink command transmitted by the detector station.

[0264] Paragraph 91. A communications system of paragraph 89, wherein the indication of the power threshold is indicated in the carrier wave signal transmitted by the carrier wave emitter.

[0265] Paragraph 92. A communications system of paragraph 89, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit the backscattered signal if a power of the received carrier wave signal is below a maximum threshold, and wherein the detector station and the controller station are configured to transmit a first downlink command to the one or more tags indicating a first maximum power threshold, to control the transmission power of a first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level, to identify one or more of the tags in a first category from backscattered signals received with the power of the first carrier wave signal at the first power level, and to receive an indication of a measured power of the first carrier wave signal, to transmit a second downlink command to the one or more tags indicating a second maximum power threshold, which is below the measured power of the first carrier wave signal , to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level higher than the first power level.

[0266] Paragraph 93. A communications system of any of paragraphs 68 to 72, wherein the detector station and the controller station are configured to select one or more of a plurality of the carrier wave emitters to transmit the carrier wave signals, to control the selected one or more of the carrier wave emitters to transmit the carrier wave signals, to determine a power of the received backscattered signals, and if a power of the received backscattered signals is below a predetermined threshold, to select one or more others of the plurality of carrier wave emitters to transmit the carrier wave signals, and to control the selected one or more other carrier wave emitters to transmit the carrier wave signals.

[0267] Paragraph 94. A communications system of paragraph 61, wherein the detector station and the controller station are configured to control the one or more carrier wave emitters selectively to be turned on to transmit the radio frequency carrier wave signals to the one or more tags or turned off and not to transmit the radio frequency carrier wave signals to the one or more tags.

[0268] Paragraph 95. A communications system of paragraph 94, wherein the detector station and the controller station are configured to determine, based on whether one or more tags are present in a deployment area of the detector station, and if the one or more tags are present in the deployment area, selectively to turn on the carrier wave emitters, and otherwise to turn off the carrier wave emitters.

[0269] Paragraph 96. A communications system of paragraph 94, wherein the detector station and the controller station are configured to determine a location of the one or more tags, and based on a location of the one or more tags with respect to a location of the detector station, selectively to turn on or turn off the carrier wave emitters based on the location of the one or more tags, to receive backscattered signals and the location of the detector station.

[0270] Paragraph 97. A communications system of paragraph 94, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the detector station and the controller station are configured to receive an indication of a location of the one or more tags from another communications device configured to communicate via the wireless access interface of the wireless communications network.

[0271] Paragraph 98. A communications system of paragraph 94, wherein the detector station and the controller station are configured to determine a power with which the received backscattered signals are received from one or more tags, based on a location of the one or more carrier wave emitters, and selectively to turn on one or more carrier wave emitters, which result in a highest power of the received backscattered signals, and otherwise to turn off the other carrier wave emitters. Paragraph 99. A communications system of paragraph 98, wherein the detector station and the controller station are configured to measure a power with which the received backscattered signals are received from one or more tags for each of the one or more carrier wave emitters, and selectively to turn on the carrier wave emitter for which the power of the received backscattered signal is the highest.

[0272] Paragraph 100. A communications system of paragraph 99, wherein the carrier wave signal includes an identifying signal from which the backscattered signal with the highest power can be identified. Paragraph 101. A communications system of paragraph 98, wherein the each of the one or more carrier wave emitters is configured to measure a power with which the received backscattered signals are received from one or more tags, and the detector station and the controller station are configured selectively to turn on the carrier wave emitter based on the power of the received backscattered signal, and to turn off the other carrier wave emitters.

[0273] Paragraph 102. A communications system of paragraph 98, wherein the each of the one or more carrier wave emitters is configured to measure a power with which the received backscattered signals are received from one or more tags, and to increase a power of the carrier wave signal transmitted by the carrier wave emitter based on the power of the received backscattered signal, until a measured power of the received back scattered signal is above a minimum.

[0274] Paragraph 103. A communications system of paragraph 98, wherein the each of the one or more carrier wave emitters is configured to measure a power with which the received backscattered signals are received from one or more tags, to transmit an indication of the measured power of the received backscattered signals to the detector station, and to receive a command from the detector either to turn on the carrier wave emitter based on the power of the received backscattered signal, or to turn off.

[0275] Paragraph 104. A communication system of paragraph 98, wherein a location of the one or more tags is known to the detector station, and the detector station and the controller station are configured to turn on the one or more carrier wave emitters depending on a location of the one or more tags.

[0276] Paragraph 105. A communications system of paragraph 98, wherein the detector station and the controller station are configured selectively to turn on each of the carrier wave emitters in turn in accordance with a predetermined schedule.

[0277] Paragraph 106. A communications system as of in any of paragraphs 61 to 105, wherein the one or more tags include circuitry to transmit a wake up signal, and each of the one or more tags is configured to determine that it has not received the carrier wave signal for a predetermined time or that a power of the carrier wave signal detected by the tag is below a predetermined threshold, and in response to the carrier wave signal not being detected or detected with a power below the predetermined threshold to the transmit the wake up signal.

[0278] Paragraph 107. A communications system of paragraph 106, wherein the detector station and the controller station are configured to detect the wake up signal and in response to detecting the wake up signal from one or more tags, to control the one or more carrier wave emitters to transmit the carrier wave signal.

[0279] Paragraph 108. A communication system of paragraph 107, wherein the carrier wave signal is transmitted in a location proximate to a location of the tag from which the wake up signal was received.

[0280] Paragraph 109. A communication system of paragraph 107, wherein the carrier wave signal is transmitted with an increased power. Paragraph 110. A communications system of any of paragraphs 61 to 109, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, the infrastructure equipment being configured to provide a wireless access interface with a time division duplex, TDD, frame structure and the one or more carrier wave emitters are configured to transmit the carrier wave signal on uplink communications resources of the TDD frame structure, so that the backscattered signals are received on the uplink communications resources.

[0281] Paragraph 111. A communications system of paragraph 110, wherein the one or more carrier wave emitters detect the TDD frame structure by monitoring signals transmitted or received by the infrastructure equipment.

[0282] Paragraph 112. A communications system of paragraph 111, wherein the one or more carrier wave emitters receive an indication of the TDD frame structure from the interface with the infrastructure equipment.

[0283] Paragraph 113. A communications system of paragraph 110, wherein the one or more carrier wave emitters determine the TDD frame structure by receiving an indication from system information broadcast by the infrastructure equipment.

[0284] Paragraph 114. A communications system of paragraph 110, wherein the one or more carrier wave emitters monitor downlink command signals transmitted by the infrastructure equipment, and based on the monitored downlink command signals determine when the carrier wave emitter should turn on to transmit the carrier wave signal and turn off not to transmit.

[0285] Numerous modifications and variations of the present disclosure are possible in light of the above teachings. It is therefore to be understood that, within the scope of the claims, the disclosure may be practiced otherwise than as specifically described herein.

[0286] In so far as embodiments of the disclosure have been described as being implemented, at least in part, by one or more software-controlled information processing apparatuses, it will be appreciated that a machine-readable medium (in particular, a non-fransitory machine-readable medium) carrying such software, such as an optical disk, a magnetic disk, semiconductor memory or the like, is also considered to represent an embodiment of the present disclosure. In particular, the present disclosure should be understood to include a non-fransitory storage medium comprising code components which cause a computer to perform any of the disclosed method(s).

[0287] It will be appreciated that the above description for clarity has described embodiments with reference to different functional units, circuitry and / or processors. However, it will be apparent that any suitable distribution of functionality between different functional units, circuitry and / or processors may be used without detracting from the embodiments.

[0288] Described embodiments may be implemented in any suitable form including hardware, software, firmware or any combination of these. Described embodiments may optionally be implemented at least partly as computer software running on one or more computer processors (e.g. data processors and / or digital signal processors). The elements and components of any embodiment may be physically, functionally and logically implemented in any suitable way. Indeed, the functionality may be implemented in a single unit, in a plurality of units or as part of other functional units. As such, the disclosed embodiments may be implemented in a single unit or may be physically and functionally distributed between different units, circuitry and / or processors.

[0289] Although the present disclosure has been described in connection with some embodiments, it is not intended to be limited to these embodiments. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in any manner suitable to implement the present disclosure.

[0290] REFERENCES

[0291] [1] RP -234058, “New SID: Study on solutions for Ambient loT (Internet of Things) in NR”. RAN plenary #102. Edinburgh. December 2023.

[0292] [2] TR38.848. “Study on Ambient loT (Internet of Things) in RAN”.

[0293] [3] “Sensing, Computing, and Communication for Energy Harvesting loTs: A Survey”. Dong Ma, Guohao Lan, Mahbub Hassan, Wen Hu, Sajal K. Das https: / / arxiv.org / abs / 1905.03949

[0294] [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.

Claims

CLAIMS1. A controller station for controlling one or more carrier wave emitters in a communications system, the controller station comprising receiver circuitry configured to receive signals, transmitter circuitry configured to transmit signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with the one or more carrier wave emitters for controlling the one or more carrier wave emitters to transmit carrier wave signals to one or more tags, wherein the control circuitry is configured with the transmitter circuitry and the controller circuitry to transmit control signals to the one or more carrier wave emitters to control transmission of radio frequency carrier wave signals to the one or more tags in response to backscattered signals detected by a detector station.

2. A controller station of claim 1, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network.

3. A controller station of claim 1, wherein the controller station is an infrastructure equipment of a radio network part of a wireless communications network and the transmitter circuitry is configured to transmit signals to communications devices via a wireless access interface provided by a wireless communications network and the receiver circuitry is configured to receive signals from the communications devices transmitted via the wireless access interface, and the interface with the controller station is formed by the wireless access interface, and the detection station is a wireless communications device which detects the backscattered signals and the controller station receives an indication of the backscattered signals received from the communications device transmitted via the wireless access interface.

4. A controller station of claim 1, wherein the interface with the one or more carrier wave emitters is formed by a wireless access interface provided by an infrastructure equipment and a communications device which includes transceiver circuitry configured to transmit and to receive radio signals via the wireless access interface provided by the wireless communications network, the communications device forming part of the one or more carrier wave emitters, the interface of the controller station formed by the infrastructure equipment uses the wireless access interface of the wireless communications network.

5. A controller station of claim 1, wherein the carrier wave emitter forms part of the controller station.

6. A controller station of claim 1, wherein the controller circuitry with the transmitter circuitry are configured to control a transmission power of carrier wave signals transmitted by the one or more carrier wave emitters, in response to a determined power of the detected backscattered signals.

7. A controller station of claim 6, wherein the controller circuitry with the receiver circuitry are configured to receive an indication of the determine power of the received backscattered signals from a detection device, to determine the transmission power of carrier wave signals based on the received indication of the determined power of the received backscattered signals to control the transmission power of the carrier wave signal transmitted by the one or more carrier wave emitters in accordance with the determined power of the received backscattered signals.

8. A controller station of claim 6, wherein the controller circuitry with the receiver circuitry are configured to receive commands for controlling a transmission power of the carrier wave signal by the one or more carrier wave emitters, and to control the transmission power of the carrier wave signal transmitted by the one or more carrier wave emitters in accordance with the received command.

9. A controller station of claim 7, wherein the controller station is configured to control the transmission power of carrier wave signals to effect a minimum received power level of the backscattered signal whilst reducing the transmission power of the carrier wave signal.

10. A controller station of claim 6, wherein the controller circuitry with the transmitter circuitry is configured to communicate a power control command to the one or more carrier wave emitters to control the transmission power of carrier wave signals, the power control command indicating whether the transmission power of the carrier wave signal should increase or decrease in accordance with the determined received power of the backscattered signal and a reception power target.

11. A controller station of claim 6, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on an aggregate of the determined power of the received backscattered signals from the plurality of the tags.

12. A controller station of claim 6, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a lowest of the determined power of the received backscattered signals from the plurality of the tags.

13. A controller station of claim 6, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine a power of a backscattered signal received from a plurality of the tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a highest of the determined power of the received backscattered signals from the plurality of the tags.

14. A controller station of claim 6, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine from the received backscattered signals an amount of interference which is likely to be caused to other devices, and to control thetransmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce interference which may be caused to the other devices by the backscattered signals.

15. A controller station of claim 14, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the interference comprises at least part of the backscattered signals which may interfere with uplink signals received by the infrastructure equipment from other communications devices communicating data via the wireless communications network.

16. A controller station of claim 6, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to transmit the carrier wave signal at a first power level, and to control the transmission power of carrier wave signals by increasing the transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters until an indication is received that one or more of the backscattered signals can be detected.

17. A controller station of claim 6, wherein the controller circuitry with the receiver and transmitter circuitry are configured to detect interference caused by the carrier wave signals when receiving the backscattered signals, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce a power of the detected interference by the carrier wave signals.

18. A controller station of claim 6, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the controller circuitry with the receiver and transmitter circuitry are configured to receive an indication of interference caused by the carrier wave signals detected by another infrastructure equipment of the radio network of a neighbouring cell, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in response to the indication of the interference to the neighbouring cell.

19. A controller station of claim 6, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission power of first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level, to identify one or more of the tags in a first category from which the backscattered signals can be received with the power of the first carrier wave signal at the first power level, to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level, which is greater than the first power level, to identify one or more of the tags in a second category from which the backscattered signals can be received with the second power of the second carrier wave signal at the secondpower level and for which the backscattered signal were not received with the power of the first carrier wave signal at the first power level, and to control the transmission power of the carrier wave signal with respect to the first power level and the second power level to receive the backscattered signals from the tags in the first category and the second category.

20. A controller station of claim 19, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals after transmitting a backscattered signal for a duration which is equal to or greater than a time for the carrier wave emitters to transmit the carrier wave signal at the second power level, so that one or more tags in the second category can be detected with the carrier wave signals transmitted at the second power level from one or more tags in the first category while the one or more tags in the first category are not transmitting.

21. A controller station of claim 19, wherein the first carrier wave signal includes a first identifier and the second carrier wave signal includes a second identifier, and the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals in response to the second carrier wave signal identified by the second identifier if they have transmitted a backscattered signal in response to the first carrier wave signal identified by the first identifier, and to transmit backscattered signals in response to the second carrier wave signal in the case that it is identified by the second identifier.

22. A controller station of claim 19, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and are configured with an identifier, and wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit a first downlink command to the one or more tags, and to control the one or more emitters to transmit a first carrier wave signal, to transmit a second downlink command to the one or more tags, the downlink command including an indication of the one or more identifiers of the first set which should not transmit backscattered signals in response to a second carrier wave signals, and, to transmit an indication to the one or more carrier wave emitters to control the transmission of the second carrier wave signal transmitted by the one or more carrier wave emitters, and to receive an indication of detect backscattered signals of the one or more tags that are not in the first set in response to the second carrier wave signal.

23. A controller station of claim 22, wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit a second downlink command to the one or more tags, the second downlink command identifying one or more of the tags of a second set from which the backscattered signals should be transmitted in response to a second carrier wave signal, which one or more tags of the second set have an identifier identified by the second downlink command,to control the transmission of a second carrier wave signal transmitted by the one or more carrier wave emitters to include a second identifier, and to detect in response to the second carrier wave signal the backscattered signals of one or more of the tags in the second set.

24. A controller station of claim 23, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the transmission of the first carrier wave signal transmitted with a first power, and to control the transmission of the second carrier wave signal transmitted with a second power greater than the first power.

25. A controller station of claim 24, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine a location of one or more tags in the first set and the second set based on the first power and the second power and an angle of arrival of the backscattered signals received from each of the one or more tags in the first set.

26. A controller station of claim 6, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit an indication of a power threshold of a received carrier wave signal, below which the one or more tags should not transmit the backscattered signal from the received carrier wave signal, and the one or more tags are configured in response to the received carrier wave signal, to determine whether a power of the received carrier wave signal is above the power threshold, and if above the power threshold to transmit the backscattered signal, and if below the power threshold to not transmit the backscattered signal.

1. A controller station of claim 26, wherein the indication of the power threshold is indicated in a downlink command transmitted by the detector station.

28. A controller station of claim 26, wherein the indication of the power threshold is indicated in the carrier wave signal transmitted by the carrier wave emitter.

29. A controller station of claim 26, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit the backscattered signal if a power of the received carrier wave signal is below a maximum threshold, and wherein the controller circuitry with the receiver and transmitter circuitry are configured to transmit a first downlink command to the one or more tags indicating a first maximum power threshold, to control the transmission power of a first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level,to identify one or more of the tags in a first category from backscattered signals received with the power of the first carrier wave signal at the first power level, and to receive an indication of a measured power of the first carrier wave signal, to transmit a second downlink command to the one or more tags indicating a second maximum power threshold, which is below the measured power of the first carrier wave signal, to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level higher than the first power level.

30. A controller station of claim 26, wherein the controller circuitry with the receiver and transmitter circuitry are configured to select one or more of a plurality of the carrier wave emitters to transmit the carrier wave signals, to control the selected one or more of the carrier wave emitters to transmit the carrier wave signals, to determine a power of the received backscattered signals, and if a power of the received backscattered signals is below a predetermined threshold, to select one or more others of the plurality of carrier wave emitters to transmit the carrier wave signals, and to control the selected one or more other carrier wave emitters to transmit the carrier wave signals.

31. A controller station of claim 3, wherein the controller circuitry with the receiver and transmitter circuitry are configured to control the one or more carrier wave emitters selectively to be turned on to transmit the radio frequency carrier wave signals to the one or more tags or turned off and not to transmit the radio frequency carrier wave signals to the one or more tags.

32. A controller station of claim 31, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine, based on whether one or more tags are present in a deployment area of the detector station, and if the one or more tags are present in the deployment area, selectively to turn on the carrier wave emitters, and otherwise to turn off the carrier wave emitters.

33. A controller station of claim 31, wherein the controller circuitry with the receiver and transmitter circuitry are configured to determine a location of the one or more tags, and based on a location of the one or more tags with respect to a location of a detector station, selectively to turn on or off the carrier wave emitters, based on the location of the one or more tags, to receive backscattered signals at the location of the detector station.

34. A controller station of claim 31, wherein the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the controller circuitry with the receiver and transmitter circuitry are configuredto receive an indication of a location of the one or more tags from another communications device configure to communicate via the wireless access interface of the wireless communications network.

35. A controller station of claim 31, wherein the controller circuitry with the receiver and transmitter circuitry are configured based on a location of the one or more carrier wave emitters and a determined power with which the received backscattered signals are received from one or more tags, selectively to turn on one or more carrier wave emitters, which result in a highest power of the received backscattered signals, and otherwise to turn off the other carrier wave emitters.

36. A controller station of claim 35, wherein the controller station is configured to receive an indication of measured power with which the received backscattered signals are received by a detection station from one or more tags for each of the one or more carrier wave emitters, and selectively to turn on the carrier wave emitter for which the power of the received backscattered signal is the highest.

37. A controller station of claim 36, wherein the carrier wave signal includes an identifying signal from which the backscattered signal with the highest power can be identified.

38. A controller station of claim 35, wherein the controller station is configured to receive an indication of a measured power with which the received backscattered signals are received from one or more tags, and selectively to turn on the carrier wave emitter based on the power of the received backscattered signal, and to turn off the other carrier wave emitters.

39. A controller station of claim 31, wherein the controller station is configured to receive an indication of a measured power with which the received backscattered signals are received from one or more tags, and to increase a power of the carrier wave signal transmitted by the carrier wave emitter based on the power of the received backscattered signal, until a measured power of the received back scattered signal is above a minimum.

40. A controller station of claim 35, wherein a location of the one or more tags is known to the controller station, and the detector station is configured to turn on the one or more carrier wave emitters depending on a location of the one or more tags.

41. A controller station of claim 35, wherein the controller circuitry with the receiver and transmitter circuitry are configured selectively to turn on each of the carrier wave emitters in turn in accordance with a predetermined schedule.

42. A controller station in claim 1, wherein the one or more tags include circuitry to transmit a wake up signal, and each of the one or more tags is configured to determine that it has not received the carrier wave signal for a predetermined time or that a power of the carrier wave signal detected by the tag is below a predetermined threshold, and in response to the carrier wave signal not being detected or detected with a power below the predetermined threshold to the transmit the wake up signal.

43. A controller station of claim 42, wherein the controller station is configured to detect the wake up signal, and in response to detecting the wakeup signal from the one or more tags, to control the one or more carrier wave emitters to transmit the carrier wave signal.

44. A controller station of claim 43, wherein the carrier wave signal is transmitted in a location of the tag from which the wake up signal was received.

45. A controller station of claim 44, wherein the carrier wave signal is transmitted with an increased power.

46. A controller station of claim 1, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, the infrastructure equipment being configured to provide a wireless access interface with a time division duplex, TDD, frame structure and the one or more carrier wave emitters are configured to transmit the carrier wave signal on uplink communications resources of the TDD frame structure, so that the backscattered signals are received on the uplink communications resources.

47. A controller station of claim 46, wherein the one or more carrier wave emitters detect the TDD frame structure by monitoring signals transmitted or received by the infrastructure equipment.

48. A controller station of claim 46, wherein the one or more carrier wave emitters receive an indication of the TDD frame structure from the interface with the infrastructure equipment.

49. A controller station of claim 46, wherein the one or more carrier wave emitters determine the TDD frame structure by receiving an indication from system information broadcast by the infrastructure equipment.

50. A controller station of claim 46, wherein the one or more carrier wave emitters monitor downlink command signals transmitted by the infrastructure equipment, and based on the monitored downlink command signals determine when the carrier wave emitter should turn on to transmit the carrier wave signal and turn off not to transmit.

51. A method of operating a controller station in a communications system comprising transmitting control signals to one or more carrier wave emitters to control transmission of radio frequency carrier wave signals to one or more tags in response to backscattered signals detected by a detector station, the control signals being transmitted via an interface with the oneor more carrier wave emitters for controlling the one or more carrier wave emitters to transmit carrier wave signals to one or more tags.

52. A detection station for operating with one or more tags, the detection station comprising receiver circuitry configured to detect signals, including backscattered signals transmitted by one or more tags, the one or more tags comprising an antenna and circuitry connected to the antenna, the control circuitry and the antenna being configured to backscatter radio frequency signals received from one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the tags, transmitter circuitry configured to transmit signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with a controller station for communicating with the controller station, for controlling one or more carrier wave emitters to transmit carrier wave signals, wherein the control circuitry is configured with the receiver circuitry and the transmitter circuitry, to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the one or more carrier wave emitters, and to cooperate with the controller station to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags in response to the detected backscattered signals.

53. A detection station of claim 52, wherein the detector station is a reader for reading the backscattered signals from the one or more tags.

54. A detection station of claim 52, wherein the detector station is a communications device and the transmitter circuitry is configured to transmit signals via a wireless access interface provided by a wireless communications network and the receiver circuitry is configured to receive signals transmitted via the wireless access interface, and the interface with the controller station is formed by the wireless access interface.

55. A detection station of claim 52, wherein the controller circuitry with the receiver circuitry are configured to determine a power of a backscattered signal received from one or the tags, and to transmit an indication of the determined received backscattered power to the controller station for the controller station to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in accordance with the determined power of the received backscattered signal from the tag.

56. A detection station of claim 52, wherein the controller circuitry with the receiver circuitry are configured to determine a power of a backscattered signal received from one or the tags, and to transmit a command signal to the controller to control the one or more carrier wave emitters based on the determined received backscattered power for the controller station to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in accordance with the determined power of the received backscattered signal from the tag.

57. A detection station of claim 55, wherein the detector station is configured to control the transmission power of carrier wave signals to effect a minimum received power level of the backscattered signal whilst reducing the transmission power of the carrier wave signal.

58. A detection station of claim 54, wherein the controller station is an infrastructure equipment forming part of a radio network of the wireless communications network.

59. A method of operating a detection station in a communications system, comprising detecting signals backscattered from one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by one or more carrier wave emitters, the one or more tags comprising an antenna and circuitry connected to the antenna, the control circuitry and the antenna being configured to backscatter radio frequency signals received from one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the tags, and cooperating with a controller station to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags in response to the detected backscattered signals.

60. A carrier wave emitter, the carrier wave emitter comprises transmitter circuitry configured to transmit a carrier wave signal to one or more tags, to be detect backscattered by the one or more tags, the one or more tags configured to backscatter radio frequency signals received from carrier wave emitters, receiver circuitry configured to receive signals, control circuitry configured to control the transmitter circuitry and the receiver circuitry, and an interface with a detection station for receiving control commands to from the detection station, wherein the control commands received from the detector station to control the carrier wave emitter to transmit the radio frequency carrier wave signals to the one or more tags.

61. A communications system comprising one or more tags comprising an antenna and circuitry connected to the antenna, the control circuitry and the antenna being configured to backscatter radio frequency signals, one or more carrier wave emitters configured to transmit a radio frequency carrier wave signal to the tags, a detector station configured to detect signals backscattered from the one or more tags, the backscattered signals being transmitted by the one or more tags in response to incident carrier wave signals transmitted by the carrier wave emitter, and a controller station connected to the one or more carrier wave emitters via an interface and configured to cooperate with the detector station to control the one or more carrier wave emitters to transmit the radio frequency carrier wave signals to the one or more tags in response to the detected backscattered signals.

62. A communications system of claim 61, wherein the detector station is a reader for detecting the backscattered signals from the one or more tags and the reader includes an interface with the controller station for indicating the detected backscattered signals.

63. A communications system of claim 62, wherein the detector station is a communications device configured to communicate via a wireless access interface provided by a wireless communications network, and the controller station is an infrastructure equipment forming part of a radio network of the wireless communications network and the interface between the controller station and the detector station is formed by the wireless access interface.

64. A communications system of claim 61, wherein the controller station and the detector station are combined and form part of an infrastructure equipment forming part of a radio network of a wireless communications network.

65. A communications system of claim 64, one or more of the carrier wave emitters comprises a communications device, the communications device including transceiver circuitry configured to transmit and to receive radio signals via a wireless access interface provided by the wireless communications network, the communications device providing the interface with the infrastructure equipment forming the detector station by using the wireless access interface of the wireless communications network.

66. A communications system of claim 64, comprising Integrated Access and Backhaul network equipment and the interface between the one or more carrier wave emitters and the infrastructure equipment forming the detector station is provided by the Integrated Access and Backhaul network.

67. A communications system of claim 62, wherein the carrier wave emitter forms part of the detection station or the controller station.

68. A communications system of claim 61, wherein the detector station is configured to determine a power of the received backscattered signals, and to cooperate with the controller station to control a transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in accordance with the determined received transmission power of the backscattered signals.

69. A communications system of claim 68, wherein the detector station is configured to determine a power of the received backscattered signals, and to transmit an indication of the determined power of the received backscattered signals to the controller station for the controller station to control a transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters.

70. A communications system of claim 69, wherein the communications device operating the detector station is configured to transmit the determined power of the received backscattered signals, and to transmit the indication of the determined power of the received backscatteredsignal to an infrastructure equipment operating as the controller station for controlling a transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters.

71. A communications system of claim 68, wherein the detector station is configured to determine a power of the received backscattered signals, to determine a power with which the carrier wave signal should be transmitted in response to the determined power of the received backscattered signals and to transmit a control command to the controller station for the controller station to transmit to the one or more carrier wave emitters to control a transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters.

72. A communications system of claim 71, wherein a communications device operating as the detector station is configured to determine the transmission power of carrier wave signals, which should be transmitted by the one or more carrier wave emitters, and to communicate a control command to the infrastructure equipment operating as the controller station for communication to the one or more carrier wave emitters to control the carrier wave emitter to transmit with the determined transmission power73. A communications system of claim 68, wherein the detector station and the controller station are configured to control the transmission power of carrier wave signals to effect a minimum received power level of the backscattered signal whilst reducing the transmission power of the carrier wave signal.

74. A communications system of claim 68, wherein the detector station and the controller station are configured to communicate a power control command to the one or more carrier wave emitters to control the transmission power of carrier wave signals, the power control command indicating whether the transmission power of the carrier wave signal should increase or decrease in accordance with the determined received power of the backscattered signal and a reception power target.

75. A communications system of claim 68, wherein the detector station and the controller station are configured to determine a power of a backscattered signal received from a plurality of the tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on an aggregate of the determined power of the received backscattered signals from the plurality of the tags.

76. A communications system of claim 68, wherein the detector station and the controller station are configured to determine a power of a backscattered signal received from a plurality of the tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a lowest of the determined powers of the received backscattered signals from the plurality of the tags.

77. A communications system of claim 68, wherein the detector station and the controller station are configured to determine a power of a backscattered signal received from a plurality ofthe tags, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters based on a highest of the determined powers of the received backscattered signals from the plurality of the tags.

78. A communications system of claim 68, wherein the detector station and the controller station are configured to determine from the received backscattered signals an amount of interference which is likely to be caused to other devices, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce interference which may be caused to the other devices by the backscattered signals.

79. A communications system of claim 68, wherein one of the detector station and the controller station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the interference comprises at least part of the backscattered signals which may interfere with uplink signals received by the infrastructure equipment from other communications devices communicating data via the wireless communications network.

80. A communications system of claim 68, wherein the detector station and the controller station are configured to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to transmit the carrier wave signal at a first power level, to determine whether one or more backscattered signals are received from the one or more tags, and to control the transmission power of carrier wave signals by increasing the transmission power of the carrier wave signals transmitted by the one or more carrier wave emitters until one or more of the backscattered signals can be detected.B.

281. A communications system of claim 68, wherein the detector station and the controller station are configured to detect interference caused by the carrier wave signals when receiving the backscattered signals, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters to reduce a power of the detected interference by the carrier wave signals.

82. A communications system of claim 68, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the detector station and the controller station are configured to receive an indication of interference caused by the carrier wave signals detected by another infrastructure equipment of the radio network of a neighbouring cell, and to control the transmission power of carrier wave signals transmitted by the one or more carrier wave emitters in response to the indication of the interference to the neighbouring cell.

83. A communications system of claim 68, wherein the detector station and the controller station are configured to control the transmission power of a first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level,to identify one or more of the tags in a first category from which the backscattered signals can be received with the power of the first carrier wave signal at the first power level, to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level, which is greater than the first power level, to identify one or more of the tags in a second category from which the backscattered signals can be received with the second power of the second carrier wave signal at the second power level, which one or more tags in the second category from which the backscattered signals were not received with the power of the first carrier wave signal at the first power level, and to control the transmission power of the carrier wave signal with respect to the first power level and the second power level to receive the backscattered signals from the tags in the first category and the second category.

84. A communication system of claim 83, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals after transmitting a backscattered signal for a duration which is equal to or greater than a time for the carrier wave emitters to transmit the carrier wave signal at the second power level, so that one or more tags in the second category can be detected with the carrier wave signals transmitted at the second power level from one or more tags in the first category while the one or more tags in the first category are not transmitting.

85. A communication system of claim 83, wherein the first carrier wave signal includes a first identifier and the second carrier wave signal includes a second identifier, and the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit, and the one or more tags are configured not to transmit the backscattered signals in response to the second carrier wave signal if they have transmitted a backscattered signal in response to the carrier wave signal identified by the first identifier, and to transmit backscattered signals in response to the second wave signal in the case that it is identified by the second identifier.

86. A communication system of claim 83, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and are configured with an identifier, and wherein the detector station and the controller station are configured to transmit a first downlink command to the one or more tags, a first carrier wave signal transmitted by the one or more carrier wave emitters, to receive from the one or more tags backscattered signals containing an identifier identifying each of the one or more tags of the first set, to transmit a second downlink command to the one or more tags, the downlink command including an indication of the one or more identifiers of the first set which should not transmit backscattered signals in response to a second carrier wave signals, andto transmit an indication to the one or more carrier wave emitters to control the transmission of a second carrier wave signal transmitted by the one or more carrier wave emitters, and to detect in response to the second carrier wave signal the backscattered signals of one or more of the tags that are not in the first set.

87. A communication system of claim 83, wherein the detector station and the controller station are configured to control the transmission of the first carrier wave signal transmitted with a first power, and to control the transmission of the second carrier wave signal transmitted with a second power greater than the first power.

88. A communication system of claim 87, wherein the detector station and the controller station are configured to determine a location of one or more tags in the first set and the second set based on the first power and the second power and an angle of arrival of the backscattered signals received from each of the one or more tags in the first set.

89. A communications system of claim 68, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit or not to transmit and wherein the detector station and the controller station are configured to transmit an indication of a power threshold of a received carrier wave signal, below which the one or more tags should not transmit the backscattered signal from the received carrier wave signal, and the one or more tags are configured in response to the received carrier wave signal, to determine whether a power of the received carrier wave signal is above the power threshold, and if above the power threshold to transmit the backscattered signal, and if below the power threshold to not transmit the backscattered signal.

90. A communications system of claim 89, wherein the indication of the power threshold is indicated in a downlink command transmitted by the detector station.

91. A communications system of claim 89, wherein the indication of the power threshold is indicated in the carrier wave signal transmitted by the carrier wave emitter.

92. A communications system of claim 89, wherein the one or more tags are configured to control transmission of the backscattered signals to transmit the backscattered signal if a power of the received carrier wave signal is below a maximum threshold, and wherein the detector station and the controller station are configured to transmit a first downlink command to the one or more tags indicating a first maximum power threshold, to control the transmission power of a first carrier wave signal transmitted by the one or more carrier wave emitters to transmit the first carrier wave signal at a first power level,to identify one or more of the tags in a first category from backscattered signals received with the power of the first carrier wave signal at the first power level, and to receive an indication of a measured power of the first carrier wave signal, to transmit a second downlink command to the one or more tags indicating a second maximum power threshold, which is below the measured power of the first carrier wave signal , to control the transmission power of a second carrier wave signal transmitted by the one or more carrier wave emitters to transmit the second carrier wave signal at a second power level higher than the first power level.

93. A communications system of claim 68, wherein the detector station and the controller station are configured to select one or more of a plurality of the carrier wave emitters to transmit the carrier wave signals, to control the selected one or more of the carrier wave emitters to transmit the carrier wave signals, to determine a power of the received backscattered signals, and if a power of the received backscattered signals is below a predetermined threshold, to select one or more others of the plurality of carrier wave emitters to transmit the carrier wave signals, and to control the selected one or more other carrier wave emitters to transmit the carrier wave signals.

94. A communications system of claim 61, wherein the detector station and the controller station are configured to control the one or more carrier wave emitters selectively to be turned on to transmit the radio frequency carrier wave signals to the one or more tags or turned off and not to transmit the radio frequency carrier wave signals to the one or more tags.

95. A communications system of claim 94, wherein the detector station and the controller station are configured to determine, based on whether one or more tags are present in a deployment area of the detector station, and if the one or more tags are present in the deployment area, selectively to turn on the carrier wave emitters, and otherwise to turn off the carrier wave emitters.

96. A communications system of claim 94, wherein the detector station and the controller station are configured to determine a location of the one or more tags, and based on a location of the one or more tags with respect to a location of the detector station, selectively to turn on or turn off the carrier wave emitters based on the location of the one or more tags, to receive backscattered signals and the location of the detector station.

97. A communications system of claim 94, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, and the detector station and the controller station are configuredto receive an indication of a location of the one or more tags from another communications device configured to communicate via the wireless access interface of the wireless communications network.

98. A communications system of claim 94, wherein the detector station and the controller station are configured to determine a power with which the received backscattered signals are received from one or more tags, based on a location of the one or more carrier wave emitters, and selectively to turn on one or more carrier wave emitters, which result in a highest power of the received backscattered signals, and otherwise to turn off the other carrier wave emitters.

99. A communications system of claim 98, wherein the detector station and the controller station are configured to measure a power with which the received backscattered signals are received from one or more tags for each of the one or more carrier wave emitters, and selectively to turn on the carrier wave emitter for which the power of the received backscattered signal is the highest.

100. A communications system of claim 99, wherein the carrier wave signal includes an identifying signal from which the backscattered signal with the highest power can be identified.

101. A communications system of claim 98, wherein the each of the one or more carrier wave emitters is configured to measure a power with which the received backscattered signals are received from one or more tags, and the detector station and the controller station are configured selectively to turn on the carrier wave emitter based on the power of the received backscattered signal, and to turn off the other carrier wave emitters.

102. A communications system of claim 98, wherein the each of the one or more carrier wave emitters is configured to measure a power with which the received backscattered signals are received from one or more tags, and to increase a power of the carrier wave signal transmitted by the carrier wave emitter based on the power of the received backscattered signal, until a measured power of the received back scattered signal is above a minimum.

103. A communications system of claim 98, wherein the each of the one or more carrier wave emitters is configured to measure a power with which the received backscattered signals are received from one or more tags, to transmit an indication of the measured power of the received backscattered signals to the detector station, and to receive a command from the detector either to turn on the carrier wave emitter based on the power of the received backscattered signal, or to turn off.

104. A communication system of claim 98, wherein a location of the one or more tags is known to the detector station, and the detector station and the controller station are configured to turn on the one or more carrier wave emitters depending on a location of the one or more tags.

105. A communications system of claim 98, wherein the detector station and the controller station are configured selectively to turn on each of the carrier wave emitters in turn in accordance with a predetermined schedule.

106. A communications system as claimed in claim 61 , wherein the one or more tags include circuitry to transmit a wake up signal, and each of the one or more tags is configured to determine that it has not received the carrier wave signal for a predetermined time or that a power of the carrier wave signal detected by the tag is below a predetermined threshold, and in response to the carrier wave signal not being detected or detected with a power below the predetermined threshold to the transmit the wake up signal.

107. A communications system of claim 106, wherein the detector station and the controller station are configured to detect the wake up signal and in response to detecting the wake up signal from one or more tags, to control the one or more carrier wave emitters to transmit the carrier wave signal.

108. A communication system of claim 107, wherein the carrier wave signal is transmitted in a location proximate to a location of the tag from which the wake up signal was received.

109. A communication system of claim 107, wherein the carrier wave signal is transmitted with an increased power.

110. A communications system of claim 61, wherein the detector station is an infrastructure equipment forming part of a radio network of a wireless communications network, the infrastructure equipment being configured to provide a wireless access interface with a time division duplex, TDD, frame structure and the one or more carrier wave emitters are configured to transmit the carrier wave signal on uplink communications resources of the TDD frame structure, so that the backscattered signals are received on the uplink communications resources.

111. A communications system of claim 110, wherein the one or more carrier wave emitters detect the TDD frame structure by monitoring signals transmitted or received by the infrastructure equipment.

112. A communications system of claim 111, wherein the one or more carrier wave emitters receive an indication of the TDD frame structure from the interface with the infrastructure equipment.

113. A communications system of claim 110, wherein the one or more carrier wave emitters determine the TDD frame structure by receiving an indication from system information broadcast by the infrastructure equipment.

114. A communications system of claim 110, wherein the one or more carrier wave emitters monitor downlink command signals transmitted by the infrastructure equipment, and based on the monitored downlink command signals determine when the carrier wave emitter should turn on to transmit the carrier wave signal and turn off not to transmit.

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