Methods and apparatuses for single or dual frequency activation for an A-IoT system

Abstract

Methods and apparatuses are disclosed for single or dual frequency activation for an A-IoT (Ambient-Internet of Things) system. According to a first aspect an apparatus (e.g. reader device) comprises

Description

Technical Field 5 This specification describes systems, methods, and apparatus for an ambient internet of things (A-IoT) system. Background The number of internet of things (loT) connections has been growing rapidly in recent 10 years and is predicted to be hundreds of billions by 2030. Typical loT devices can consume tens or hundreds of milliwatts power during transceiving, w hile the cost for such devices can be around a few dollars. With a greater number of ‘things’ expected to be interconnected, it can be expected that resource consumption of loT devices (e.g., in terms of power consumption, component usage, maintenance requirements, size, cost, 15 etc) will increase. For instance, regular replacement of batteries for loT devices may become impractical due to the large amount of consumption of materials and manpower. As such, in some cases, loT devices which can be powered using energy harvested from environments may be used (e.g., for self-sustainable communications, such as in applications with a large number of devices such as ID tags and sensors). As 20 such, as the number of loT devices and their connections increases (e.g., with the progression towards the so called “internet of everything”), it may be desirable to provide loT derices with lower (e.g., ten or even a hundred times) power consumption and cost (e.g., by reducing required components, etc) and. This may be particularly the case for applications requiring batteryless derices. 25 Technologies supporting batteryless derices include radio frequency identification (RFID). RFID uses techniques such as envelope detection for downlink data reception, and backscatter communication for uplink data transmission. In some cases, the power consumption of commercial passive RFID tags can be as low as, for instance, 1 30 microwatt. However, RFID is designed for short-range communications, with a typical effective range of, for instance, less than 10 meters. In addition, the relatively simple transmission scheme of RFID can limit the link budget and capability of supporting a scalable network. Other low power (e.g., few or tens of microwatts) backscattering technologies based on, for instance, Wi-Fi, Bluetooth, UWB, and LORA, have also been proposed, but are generally focused on independent detailed techniques for particular optimization targets. Summary 5 In a first aspect, this specification relates to a method comprising: responsive to a determination of an occurrence of a trigger condition, causing an apparatus to switch between a first receiving mode and a second receiving mode, wherein in the first receiving mode, the apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type on a first 10 frequency, and in the second receiving mode, the apparatus is configured to receive, from the passive device, a second type of signal comprising a backscattered signal using a second modulation type on a second frequency. In some examples, the first modulation type comprises an on-off keying (OOK) modulation type, and the second modulation type comprises a binary phase-shift 15 keying (BPSK) modulation type. In some examples, the method further comprises: responsive to the determination of the occurrence of the trigger condition, causing an activator apparatus to switch between a first transmission mode in which the activator apparatus transmits a single 20 frequency activation signal to the passive device and a second transmission mode in which the activator apparatus transmits a dual frequency activation signal to the passive device. In some examples, causing the apparatus to switch between the first receiving mode 25 and the second receiving mode responsive to determining the occurrence of a trigger condition comprises: determining that an expected signal of the first type of signal has not been received from the passive device or that a signal of the first type of signal has been received from the passive device with a signal strength below- a first threshold signal strength; transmitting a first request message comprising a request for the 30 apparatus to switch from the first receiving mode to the second receiving mode; and responsive to receiving a configuration message responsive to the first request message to switch from the first receiving mode to the second receiving mode, switching from the first receiving mode to the second receiving mode. 35 In some examples, causing the apparatus to switch between the first receiving mode and the second receiving mode responsive to determining the occurrence of a trigger condition comprises: determining that a signal of the second type of signal has been received from the passive device with a signal strength above a second threshold signal strength; transmitting a second request message comprising a request for the apparatus to switch from the second receiving mode to the first receiving mode; and responsive to 5 receiving a configuration message responsive to the second request message to switch from the second receiving mode to the first receiving mode, switching from the second receiving mode to the first receiving mode. In some examples, the method further comprises: receiving, from the passive device, 10 data indicative of a capability of the passive device to support operating in a first mode corresponding to the first receiving mode and / or a second mode corresponding to the second receiving mode. In a second aspect, this specification relates to a method comprising: responsive to a 15 determination of an occurrence of a trigger condition, transmitting a configuration message to cause a reader apparatus to switch between a first receiving mode and a second receiving mode, wherein in the first receiving mode, the reader apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type on a first frequency, and in the 20 second receiving mode, the reader apparatus is configured to receive, from the passive device, a second type of signal comprising a backscattered signal using a second modulation type on a second frequency. In some examples, the method further comprises: responsive to the determination of 25 the occurrence of the trigger condition, transmitting a configuration message to cause an activator apparatus to switch between a first transmission mode in which the activator apparatus transmits a single frequency activation signal to the passive device and a second transmission mode in which the activator apparatus transmits a dual frequency activation signal to the passive device. 30 In some examples, causing the reader apparatus to switch between the first receiving mode and the second receiving mode responsive to determining the occurrence of a trigger condition comprises: receiving a communication indicating that an expected signal of the first type of signal received has not been received from the passive device 35 by the reader apparatus or that a signal of the first type of signal has been received from the passive device by the reader apparatus with a signal strength below a first threshold signal strength; and transmitting a configuration message to cause the reader apparatus to switch from the first receiving mode to the second receiving mode. In some examples, the method further comprises: responsive to receiving the 5 communication indicating that the expected signal of the first type of signal has not been received from the passive device by the reader apparatus or that the signal of the first type of signal has been received from the passive device by the reader apparatus with a signal strength below the first threshold signal strength, transmitting a configuration message to cause the activator apparatus to switch from a first 10 transmission mode in which the activator apparatus transmits a single frequency activation signal to a second transmission mode in which the activator apparatus transmits a dual frequency activ ation signal. In some examples, causing the reader apparatus to switch between the first receiving 15 mode and the second receiving mode responsive to determining the occurrence of a trigger condition comprises: receiving a communication indicating that a signal of the second type of signal has been received from the passive device by the reader device with a signal strength above a second threshold signal strength; and transmitting a configuration message to cause the reader device to switch from the second receiving 20 mode to the first receiving mode. In some examples, the method further comprises: responsive to receiving the communication indicating that the signal of the second type of signal has been received from the passive device by the reader device with a signal strength above the second 25 threshold signal strength, transmitting a configuration message to cause the activator apparatus to switch from a second transmission mode in which the activator apparatus transmits a dual frequency activation signal to a first transmission mode in which the activator apparatus transmits a single frequency activation signal. 30 In some examples, the method further comprises: initially configuring the reader apparatus to operate in the first receiving mode and / or initially configuring the activator apparatus to operate in the first transmission mode. In some examples, the method further comprises: receiving data indicative of a 35 capability of the passive device to support operating in a first mode corresponding to the first receiving mode and / or a second mode corresponding to the second receiving mode. In a third aspect, this specification relates to a method comprising: responsive to 5 determining to switch between a first transmission mode and a second transmission mode, causing an apparatus to switch between a first transmission mode in which the apparatus transmits a first type of activation signal to a passive device and a second transmission mode in which the apparatus transmits a second type of activation signal to the passive device. 10 In some examples, the first type of activation signal comprises a single frequency activation signal and / or a first state indication and wherein the second type of activation signal comprises a dual-frequency activation signal and / or a second state indication, wherein the first state indication causes the passive device to operate in a 15 first mode corresponding to the first transmission mode and the second state indication causes the passive device to operate in a second mode corresponding to the second transmission mode. In some examples, causing the apparatus to switch between a first transmission mode 20 and a second transmission mode responsive to determining to switch between the first transmission mode and the second transmission mode comprises: responsive to receiving a configuration message, switching from the first transmission mode to the second transmission mode. 25 In some examples, causing the apparatus to switch between a first transmission mode and a second transmission mode responsive to determining to switch between the first transmission mode and the second transmission mode comprises: responsive to receiving a configuration message, switching from the second transmission mode to the first transmission mode. 30 In some examples, the method further comprises: transmitting a request for the passive device to provide data indicative of a capability of the passive device to support operating in a first mode corresponding to the first transmission mode and / or a second mode corresponding to the second transmission mode. In a fourth aspect, this specification relates to a method comprising: responsive to receiving an activation signal comprising a first state indication, reflecting a backscattered signal with a first modulation type on a first frequency; and responsive to receiving an activation signal comprising a second state indication, reflecting a 5 backscattered signal with a second modulation type on a second frequency. According to a further aspect of this specification, there is described an apparatus comprising means for performing the method of any of the first to fourth aspects. 10 According to a further aspect of this specification, there is described an apparatus comprising at least one processor, and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus to perform any of the methods described herein. 15 According to a further aspect of this specification, there is described a computer program product / non-transitory computer readable medium storing computer-readable instructions that, when executed by a computer (such as a network node), cause the computer to perform any one or more of the methods described herein. 20   Brief Description of the Drawings Example embodiments will now be described by way of non-limiting examples, with reference to the accompanying drawings, in which: FIG. 1 shows an example of an A-IoT system; 25 FIG. 2 shows an example backscatter operation for two types of passive devices; FIGs. 3A and 3B show example message flow sequences; FIGs. 4, 5 and 6 show flow diagrams of example methods of operating various apparatus in an A-IoT system; FIG. 7 shows an apparatus according to some example embodiments, which may form 30 at least a part of an A-IoT system; and FIG. 8 shows a non-transitory media according to some embodiments. Detailed Description In the description and drawings below, like reference numerals refer to like elements 35 throughout. When providing passive devices in a network (e.g., a cellular network), the power which can be generated using energy harvesting considering the (limited) size of such devices may be limited. For instance, typical cellular devices may consume tens or even hundreds of milliwatts power for transceiver processing. For instance, taking a 5 NarrowBand-Internet of Things (NB-IoT) module as an example, typical current consumption for receive processing may be around 6omA with supply voltage higher than 3.1V. For transmit processing, the current consumption can be around 70mA for transmit processing at odBm transmit power. Furthermore, the output power provided by a typical energy harvester (considering the small size of a few square centimetres for 10 practical devices) may be below 1 milliwatt. Since, in this case, the available power is less than the consumed power, it may be impractical to power cellular devices directly by energy harvesting. One possible solution to this problem is to integrate energy harvesting with 15 rechargeable batteries or supercapacitors. However, both rechargeable batteries and supercapacitors may suffer from shortened lifetime in practical cases. For instance, it may be difficult to provide constant charging current or voltage by energy harv esting, while long-time continuous charging is needed due to the relatively small power output available from energy harvesting. In addition, inconstant charging current and long-20 time continuous charging are both harmful to battery life. Moreover, as a small size (e.g., button) battery can generally only provide current of a few tens of milliamps, batteries with a much larger size (e.g., AA battery) may instead be used to power cellular devices. Such larger batteries can be even larger than the 25 module itself. Similarly, to store energy for a proper duration of operation (e.g., one second), the required capacitance of a supercapacitor may be around hundred millfarads. The size of such supercapacitors may also be larger than an NB-IoT module. Thirdly, both rechargeable batteries and supercapacitors can be more expensive than the module itself. 30 As such, it may be desirable to provide passive devices and techniques related to the use of such passive devices which enable A-IoT systems for various applications e.g., cellular networks. 35 Implementations described herein relate to operations of an loT system including a loT device which can be powered using energy harvested from environments (otherwise termed, a passive device, a passive radio, an ambient device, an A-IoT device, an A-IoT tag, etc.). In other words, a passive device can harness energy from wireless signals sent on specific carriers and / or bandwidths to charge a simple circuitry that, once activated, will emit / reflect a signal which encodes at least the ID of the passive radio 5 (and in some cases, for instance, capability information as described herein, sensor data, etc). Such loT systems can be known as A-IoT systems. Some implementations relate to use of the such A-IoT systems with networks (e.g., cellular networks such as those associated with 3GPP technologies). 10 Turning to FIG. 1, an example of an A-IoT system is depicted. As depicted in FIG. 1, an loT system can comprise one or more of a session control unit no (which might also be referred to as a session control apparatus), an activator 120 (which might also be referred to as an activator apparatus), a reader 130 (which might also be referred to as a reader apparatus), and a passive device 140. 15 As described herein, the passive device 140 may be capable of harnessing energy over a range of frequencies and listening for activation signals. Once an activation signal is detected, the passive device can emit / reflect a signal which may include data specific to the passive device 140 (e.g., an identification (ID) number or string), and in some 20 implementations, for instance, capability information as described herein, sensor data, etc. Passive devices may be provided in a variety of forms. For instance, fully passive devices can be entirely batteryless with no energy storage capability at all. Such devices 25 may be completely dependent on the availability of an external source of energy. Semi passive devices can include limited energy storage capabilities that do not need to be replaced or recharged manually. Similarly some devices may include components for active transmission (e.g., active RF components for transmission) whilst other devices may include components only for passive transmission (e.g., backscattering 30 transmission). A passive device’s peak power availability may be based on, for instance, its form factor (which may be determined by the device’s intended use cases), its energy source, etc. As an example, tvpe A passive devices may have relatively simple levels of design 35 complexity (e.g., comparable to UHF RFID), and may not include energy storage, or components for independent signal generation or amplification. Instead, type A passive devices can include components for backscattering transmission. As another example, type B passive devices also may not include components for 5 independent signal generation, and thus make use of components for backscattering transmission. However, type B passive devices may have a higher level of design complexity relative to type A passive devices, and may include energy storage and components for amplification of reflected signals. Type B devices may provide lower backscatter reflection loss (e.g., compared to a type A device) by making use of their 10 stored energy reserves. As such, type B devices may offer increased coverage range (e.g., compared to type A devices). As another example, type C passive devices can have a higher level of design complexity still (however, still orders of magnitude lower than, for instance, NB-IoT modules). For 15 instance, type C devices can include energy storage, and components for independent signal generation (e.g., active RF components for transmission). Type A devices might be expected to consume up to around 10 microwatts. Type C devices might be expected to consume up to around 1 milliwatt. Type B devices might 20 be expected to consume power somewhere between the power consumed by type A devices and the power consumed by type C devices. Since type A devices do not include energy storage, these devices can charge on the activation signal to wake up and initiate ID / data modulated backscattering. To sustain 25 the backscattering transmission, type A devices can use 011 / off keying (OOK) modulation. For instance, the modulation may include switching the antenna load between two states: a matched state, Xo, for energy absorbing charging, and an unmatched (or otherwise termed, mismatched) reflecting state. Since a type A device may effectively only reflect the activation signal half of the time, the backscatter 30 modulation factor, M, can be calculated as: -* 1X1 -XOI 2 1 1 = 0.25 where Xo=o and Xl=l. As described herein, type B devices may include energy storage which can be filled with energy which may be harvested up front (e.g., before any backscattering). As such, type B devices may not need to harvest energy from the activation signal while modulating the backscatter. Type B devices consequently may reflect the activation all the time 5 while performing modulation (e.g., BPSK or any other phase modulation) betw een two or more reflective states. As such, the backscatter modulation factor, M, can be calculated as: / 1 ? M = ( —*|X1-XOH =1 io where Xo=-1 and Xl=l. For instance, turning briefly to FIG. 2, an example backscatter operation of two different types of passive devices is depicted. 15 As indicated byline 210 of FIG. 2, at To, an activator 120 may not transmit an activation signal. As also indicated by line 210, at Ti, the activator 120 can start to transmit an activation signal. 20 As indicated by line 220, a type A device 140A within range of the activator 120 may not receive an activation signal between To and Ti. Between Ti and T2, the type A device 140A can receive the activation signal, and can thus charge its circuitry. This time period, indicated by arrows 222, may be referred to as an initial charge time for the type A device. From T2, the type A device 140A can start reflecting backscattered 25 signals (e.g., using OOK). For instance, the type A device 140A can switch the antenna load between an unmatched state St (e.g., during reflection), and a matched state S2 (e.g., during charging). As indicated by line 230, a type B device 140B within range of the activator 120 may not 30 receive an activation signal between To and Ti. Between Ti and T2, the type B device 140A can receive the activation signal. As described herein, type B devices include their own energy storage (which may be charged by other means than the activation signal and / or at another time). This time period, indicated by arrows 232, may be referred to as an initial charging time for the type B device. In some situations, the type B device 35 may not start backscattering until T2. at which point it can be assumed that the type B device has completed up front energy harvesting if needed, depending on its current level of energy storage. In some other situations, if the energy storage of the type B device 140 B is sufficiently charged, the type B device 140B can immediately start backscattering the activation signal (e.g., at Ti), such that the initial charging time can 5 be shorter or eliminated entirely. For instance, in some situations, the initial charging / activation time for a type B device 140B may be shorter than an initial charging time for a type A device 140A e.g., if the type B device 140B has harvested energy before the activation signal has started to be emitted, and in other situations, the initial charging / activation time for a type B device 140 B may be greater than the 10 initial charging time for type A devices 140A, e.g., if the type B device 140B needs to charge before back scattering (as the type B device 140 B needs energy for the full BPSK modulation duration). In the example embodiment of FIG. 2, from T2, the type B device 140A can start reflecting backscattered signals (e.g., using BPSK). For instance, the type B device 140B can switch the antenna load between an unmatched phase 1 15 state Si, and an unmatched phase 2 state S3- Since the activation signal is reflected at all times (e.g., because BPSK is used), at unmatched phase 1 state Si and unmatched phase 2 state S3, the activation signal cannot be used to charge the device. Instead, as described herein, other means must be used. 20 From the above it can be seen that type A devices may be advantageous in that they do not require “up-front energy harvesting” (e.g., since they do not include an energy storage) which may require additional resources (or alternative harvesting techniques such as solar, kinetic, etc.), and can thus be accessed at any point of time when in range of an activator 120 (e.g., and a reader). On the other hand, type B devices may be 25 advantageous in that they provide relatively better coverage (e.g., by use of amplification), and can use modulation techniques (e.g., BPSK rather than OOK) which have lower error rates. Implementations described herein generally relate to aspects of an A-IoT system 30 involving a type A device that can use phase modulation (e.g., BPSK) when activated with a dual frequency activation signal and a different modulation technique (e.g., OOK) when activated with a single frequency activation signal. For instance, such devices may, when receiving a dual frequency activation signal, use the first activation frequency for constant charging. Such devices may also use BPSK modulation 35 backscatter on the second activation frequency. When receiving the single frequency signal, such devices may perform OOK modulation on the first activation frequency. Such devices may not necessarily be capable of detecting whether the activation signal is single or dual frequency and may not therefore be capable of determining which modulation type to use absent the techniques described herein. In addition, such devices may not necessarily be capable of performing both modulation types 5 simultaneously at the different activation frequencies. Use of dual frequency activation signals can result in increased coverage of the link between a passive device and a reader (e.g., due to the increased modulation gain of BPSK compared to 00K). However, dual frequency activation signals require 10 increased resource allocation. As such, it may be beneficial to only activate the use of dual frequency activation signals when required. Implementations described herein therefore relate to enabling a passive device to be aware of the state of the configured activation signal and thereby use the expected modulation form. 15 Although implementations are generally described herein in relation to a type A device, it will be understood that the operations described herein may be used with other devices. For instance, the operations may be used with type B or type C devices (e.g., when operating in a resource conserving mode). 20 Turning now back to FIG. 1, the A-IoT system too can include a session control unit (SOU) no. The SCU no can generally control the A-IoT system too, for instance, by transmitting configuration signals to one or more other apparatus of the A-IoT system too (e.g., the activator 120 or the reader 130). The SCU no can be for instance, provided as an independent unit, provided as a separate unit implemented in any 25 device or node connected to a network (e.g., a cellular network such as a 3GPP compliant network), such as a gNB, a UE, an LMF, etc, integrated with the activator 120 and / or the reader 130, etc. In some cases, the session control unit can be omitted, with the various communication described herein being redirected accordingly (e.g., the activator 120 and the reader 130 can communicate with each other directly). 30 The SCU no can store capability information corresponding to the passive device 140. For instance, the capability information can be indicative of the passive device’s capability of supporting single frequency activation (e.g., for OOK modulation) and dual frequency modulation (e.g., for BPSK modulation). As described herein, BPSK 35 modulation can be utilized to increase the passive device 140 to reader 130 coverage, as BPSK modulation may provide a 6 dB gain advantage over OOK (e.g., since BPSK may provide a modulation factor of M=1 whilst OOK may provide a modulation factor of M=o.25). Although implementations are generally described herein in relation to OOK and BPSK, it will be appreciated that any respective suitable modulation techniques may be used. 5 The capability information may be associated with a particular type (e.g., manufacturer, model number, etc) of passive device 140, a unique ID associated with the passive device 140, etc. In some implementations, the capability information can be hard coded or programmed into the memory of the SCU no (e.g., by a manufacturer, an 10 installer, an end-user, via an update received by the SCU no, etc). Additionally or alternatively, the capability information can be dynamically obtained by the SCU no, for instance, by requesting passive device capability reports for newly discovered passive devices in the A-IoT network, as described herein. 15 As also depicted in FIG. 1 the A-IoT system too includes an activator 120. The activator 120 can be a device that sends an activation signal targeted at waking up the passive device 140, as described herein. As also depicted in FIG. 1, the A-IoT system too includes a reader 130. The reader 130 20 can be a device that listens and detects the passive radio signals, e.g., backscattered signals, from the passive device 140. In some implementations, the reader 130 can be collocated with the activator 120. Although in FIG.1 only a single instance of the activator 120, the reader 130, and the 25 passive device 140 is illustrated, it should be understood that this is for the sake of illustration only and is in no way limiting. For instance, an A-IoT system too can include any number of activators 120, readers 130 and passive devices 140, which may be controlled in concert, independently, etc. As an example, there may be a plurality of passive devices 140 in the A-IoT system too (e.g., 2,10, too, 1000, etc). 30 The A-IoT system too described herein can be used in any suitable application or deployment scenario. For instance, the A-IoT too system can be used in an indoor environment or an outdoor environment. In some implementations, the A-IoT system too can be used in association with a base station (e.g. macro / micro / pico cells-based 35 deployments). In some implementations, the A-IoT system too can be configured for use with one or more connectivity' topologies, including e.g., which node(s), (e.g., basestation, UE, relay, repeater, etc) can communicate with target devices. In some implementations, the A-IoT system 100 can be configured for use with different wireless technologies, such as TDD, FDD, frequency bands in licensed or unlicensed spectrum, etc. In some implementations, the A-IoT system can be configured to coexist 5 with UEs and infrastructure in frequency bands for existing technologies (e.g., existing 3GPP technologies). In some implementations, the A-IoT system can be configured to operate with device originated and / or device terminated traffic assumption. Turning to FIGs. 3A and 3B. an example message flow sequence in an A-IoT system too 10 is depicted. At operation 301, the SCU110 initializes / configures a device as an activator 120 in a A-loT session (e.g., by sending an initialization message to the activator 120). For instance, the device configured to act as an activator 120 may be determined to be 15 compatible as an activator (e.g., a 3GPP compatible device). At operation 302, the SCU no initialize / configures a device as a reader 130 in a A-IoT session (e.g., by sending an initialization message to the reader 130). For instance, the device configured to act as a reader 130 may be determined to be compatible as reader 20 (e.g., a 3GPP compatible device). At operation 303 the SCU no initially configures the activator 120 for single frequency activation. This can be performed as single frequency activation may require less uplink resources (e.g., relative to dual frequency activation). Similarly, at operation 25 304, the SCU no initially configures the reader 130 for OOK modulation on a first frequency. In some implementations, the SCU no can request OOK and BPSK modulation capability reports for all newly discovered passive devices 140 in the network. The 30 received passive device capability- report be provided as an indication of support of BPSK modulation when exposed with a dual frequency activation signal. For instance, the capability report can be implemented with a simple and / or standardized code sequence after an ID of the passive device 140 (e.g., received from the passive device 140). A reply from a passive device 140 with missing information of dual modulation 35 support may be interpretated as that passive device 140 only supporting OOK modulation. For instance, at operation 305? the activator 120 can send out a passive device capability report request. The capability report request can initially be sent as a single frequency activation signal for OOK modulation (e.g., by the passive device 140). The 5 SCU no can additionally or alternatively send the capability report request (e.g., via the activator 120), which in an example embodiment can be a dual frequency activation signal for BPSK modulation (e.g., by the passive device 140), in case the passive device is out of coverage of the reader 130 when utilizing OOK modulation. 10 At operation 306, passive device(s) 140 within range and with an understanding of the capability7 report request, backscatter a reply with a capability report (e.g., a standardized code indicative of the passive device’s capability to support OOK and / or BPSK modulation). The reader 130 may receive the capability reports from the passive device(s). 15 At operation 307, the SCU receives the passive device capability reports (e.g., via the reader 130). The SCU no can thus store the received capability reports. At operation 308, the activator 120 sends a single frequency activation signal, with an 20 indication of a first state or configuration for the passive device 140. The indication of the passive device state can be implemented by including, in the activation signal, data indicative of the first state. For instance, a simple code sequence consisting of a few bits can be embedded in the activation signal. The data (e.g., the code sequence) can have a predetermined meaning (e.g., and therefore may be interpreted by the passive 25 device 140 according to this predetermined meaning). At operation 309, the passive device 140 backscatters in a first state. In particular, the passive device 140 backscatters the signal using OOK modulation on a first frequency. The passive devdee 140 may backscatter in the first state in response to receiving the 30 first state indication. The backscattered signal 130 can be received by the reader 130. At operation 310, one or more expected passive device backscattering signals are not received (e.g., within a threshold period of time) or are received with a signal strength lower than a threshold signal strength. In an example embodiment, the number and / or 35 identity of passive devices 140 in the operating in the A-IoT system 100 may be known (e.g., based on network topology information stored by the SCU no or the reader 130). If the number of received signals from the passive devices 140 is lower than the number of, or a threshold number of, passive devices 140 operating in the A-IoT system too and / or if a signal is not received from a passive device 140 known to be operating in the A-IoT system 100, it may be determined that an expected signal has not been received. 5 The threshold signal strength may be based on the sensitivity level of the reader 130 (e.g., if the signal strength is close to the sensitivity level of the reader 130, it may be assumed that the respective passive device may soon be out of range). As an example, the threshold signal strength may be + 3 dB from the sensitivity level of the reader 130. 10 In some implementations, the determination whether one or more expected passive device backscattering signals are not received or are received with a signal strength lower than a threshold signal strength may be based only on passive devices 140 known to support BPSK modulation when activated with a dual frequency activation signal (e.g., based on capability information stored by the SCU no). In other words, if, e.g., at 15 least a threshold number of the passive devices 140 which do support BPSK modulation when activated with a dual frequency activation signal are still within range (e.g., based on the received signal strength), single frequency activation can be maintained (e.g., switching to dual frequency activation for the A-IoT system too can be bypassed) even when other passive devices 140 (e.g., those which don’t support BPSK modulation when 20 activated with a dual frequency activation signal) operating in the A-IoT system too are out of range (or close to being out of range). In some additional or alternative examples, if, e.g., at least a threshold number of the passive devices 140 which do support BPSK modulation when activated with a dual frequency activation signal are out of range (or close to being out of range), e.g., based on the received signal strength, switching from 25 single frequency activation to dual frequency activation can be performed even when other passive devices 140 (e.g., those which don’t support BPSK modulation when activated with a dual frequency activation signal) operating in the A-IoT system too are still within range. It may be assumed that passive devices 140 which do not support BPSK modulation when activated with a dual frequency activation signal will continue 30 operating with OOK modulation on one of the frequencies of the dual frequency activation signal when provided with a dual frequency activation signal. In other words, it may be assumed that no additional range can be expected by providing a passive device 140 which does not support BPSK modulation with a dual frequency activation signal. In this way, resources which would otherwise be consumed in 35 providing dual frequency activation signal can be conserved. At operation 311, the reader 130 requests (e.g., via the SCU no) that the activator 120 switches to providing dual frequency activation signals and / or that the reader 130 switches to a configuration for receiving BPSK backscattered signals on the second frequency. In some implementations, the reader 130 can send an explicit request for 5 this purpose. Additionally or alternatively, the reader 130 can report a determination that one or more expected passive device backscattering signals are not received or are received with a signal strength lower than a threshold signal strength. Additionally or alternatively, the SCU 110 can determine that one or more expected passive device backscattering signals are not received or are received with a signal strength lower than 10 a threshold signal strength (e.g., based on reported signals / signal strengths from the reader 130, or the absence thereof). At operation 312, the SCU 110 configures the activator 120 for dual frequency activation (e.g., by transmission of a configuration message). Similarly, at operation 313, the SCU 15 no configures the reader 130 for receiving BPSK backscattering signals at a second frequency. In some implementations, the reader 130 may be configured to also receive OOK backscattered signals at the first (and / or second) frequency (e.g., from passive devices present which do not support BPSK backscattering in response to a dual frequency activation signal). This may be the case, for instance, when it is known (e.g., 20 based on information accessible to the SCU) that passive devices which do not support BPSK backscattering in response to a dual frequency activation signal are participating in the A-IoT system. Accordingly, at operation 314, the activator 120 sends a dual frequency signal, with an indication of a second state / configuration. The second state indication can be implemented, for instance, in a similar manner to that described in 25 relation to the first state indication. At operation 315, the passive device 140 backscatters in a second state. In particular, the passive device 140 backscatters the signal using BPSK modulation on a second frequency. The passive device 140 may backscatter in the second state based on 30 receiving the second state indication. At operation 316, all (or at least a threshold number of) expected passive device back-scattering signals are received with a signal strength above a threshold signal strength. The threshold signal strength may be based on the sensitivity level of the reader 130. 35 For instance, since the gain between OOK and BPSK is 6 dB, the threshold signal strength could be 9 dB higher than the sensitivity level of the reader 130. In some implementations, the determination whether all (or at least a threshold number of) expected passive device back-scattering signals are received with a signal strength above a threshold signal strength may be based only on passive devices 140 known to support BPSK modulation when activated with a dual frequency activation signal (e.g., 5 based on capability information stored by the SCU 110). In other words, even if other passive devices 140 (e.g., those which don’t support BPSK modulation when activated with a dual frequency activation signal) operating in the A-IoT system too are close to being out of range, switching to single frequency activation for the A-IoT system too may still occur (e.g., when at least a threshold number of expected passive device 10 backscattering signals are received with a signal strength above a threshold signal strength from passive devices supporting BPSK modulation when activated with dual frequency activation). In some additional or alternative examples, even if other passive devices 140 (e.g., those which don’t support BPSK modulation when activated with a dual frequency activation signal) operating in the A-IoT system too are received with a 15 signal strength above a threshold signal strength, dual frequency activation can be still maintained (e.g., when at least a threshold number of expected passive device backscattering signals are received with a signal strength not above a threshold signal strength from passive devices supporting BPSK modulation when activated with dual frequency activation). It may be assumed that passive devices 140 which do not 20 support BPSK modulation when activated with a dual frequency activation signal will continue operating with OOK modulation on one of the frequencies of the dual frequency activation signal when provided with a dual frequency activation signal. In other words, it maybe assumed that no additional range can be expected by continuing to provide a passive device 140 which does not support BPSK modulation with a dual 25 frequency activation signal. In this way, resources which would otherwise be consumed in continuing to provide dual frequency activation signal can be conserved. At operation 317, the reader 130 requests the activator 120 switch to single frequency activation signals (e.g., via the SCU 110), and / or the reader 130 to switch to a 30 configuration for receiving OOK signals on the first frequency. In some implementations, the reader 130 can send an explicit request for this purpose. Additionally or alternatively, the reader 130 can report a determination that all expected passive device back-scattering signals are received with at least a threshold signal strength. Additionally or alternatively, the SCU 110 can determine that all 35 expected passive device back-scattering signals are received with at least a threshold signal strength (e.g., based on reported signals / signal strengths from the reader 130, or the absence thereof). At operation 318, the SCU no can return to operation 303, to thereby configure the 5 activator 120 for single frequency passive device activation, and subsequently the reader 130 for receiving OOK back scattered signals on the first frequency, at which point the process can start again. However, since it can be assumed that the capabilities of the passive device 140 is known, (and if there is no indication that a newly added passive device is present), operations 305 306, and 307 can be omitted. 10 In this way, the operations described herein can provide resource optimization (e.g., by dynamically allocating resources for single or dual frequency activation signals) whilst effectively increasing the coverage of the link between passive devices 140 and the reader 130. For instance, the coverage may be increased by a factor of 2, due to the 15 increased modulation gain of 6 dB for BPSK compared to OOK. In some cases, the increase in coverage can be less than 2 e.g., due to implementation loss of adding the capability’ to switch between OOK and BPSK at the passive device. For instance, assuming an implementation loss of less than 0.5 dB, which is equal to a modulation factor of 0.89, a modulation gain of 5.5 dB can be expected. 20 Turning to FIG. 4, a flow diagram of an example method of operating an apparatus (e.g., a reader apparatus) in an A-IoT system (e.g., the A-IoT system too of FIG. 1) is depicted. 25 At operation S4.1, an occurrence of a trigger condition can be determined (e.g., as described in relation to one or more of operations 310, 311,313,316,317, and 318 of FIGs. 3A and 3B). For instance, the determination of the occurrence of a trigger condition may be based on a signal strength of a signal received from a passive device, or on a communication received from another apparatus (e.g., a session control 30 apparatus). At operation S4.2, responsive to the determination that a trigger condition has occurred, switching between a first receiving mode and a second receiving mode is caused (e.g., as described in relation to one or more of operations 311, 313,317, and 318 35 of FIG. 3A and 3B). In the first receiving mode, the apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type (e.g., OOK modulation) on a first frequency. In the second receiving mode, the apparatus is configured to receive, from the passive device, a second type of signal comprising a backscattered signal using a second modulation type (e.g., BPSK modulation) on a second frequency. In some implementations, in the 5 second receiving mode, the apparatus may be configured to also receive signals of the first type (e.g., from passive devices present which do not support BPSK backscattering in response to a dual frequency activation signal). This maybe the case, for instance, when it is known (e.g., based on information accessible to an SCU) that passive devices which do not support BPSK backscattering in response to a dual frequency activation 10 signal are participating in the A-loT system. For instance, it may be determined that an expected signal of the first type of signal has not been received from the passive device or that a signal of the first type of signal has been received from the passive device with a signal strength below a first threshold 15 signal strength (e.g., as described in relation to operation 310 of FIG. 3A). Responsively, a first request message comprising a request for the apparatus to switch from the first receiving mode to the second receiving mode can be transmitted (e.g., to a session control apparatus). In response to receiving a configuration message responsive to the request (e.g., from the session control apparatus) to switch from the 20 first receiving mode to the second receiving mode, the apparatus can switch from the first receiving mode to the second receiving mode. Additionally or alternatively, it may be determined that a signal of the second type of signal has been received from the passive device with a signal strength above a second 25 threshold signal strength (e.g., as described in relation to operation 316 of FIG. 3B). In response, a second request message comprising a request for the apparatus to switch from the second receiving mode to the first receiving mode can be transmitted (e.g., to a session control apparatus). In response to receiving a configuration message responsive to the request (e.g., from the session control apparatus) to switch from the 30 second receiving mode to the first receiving mode, the apparatus can switch from the second receiving mode to the first receiving mode. In some implementations, the example method of FIG. 4 can further include causing an activator apparatus to switch between a first transmission mode and a second 35 transmission mode responsive to the determination of the occurrence of the trigger condition (e.g., as described in relation to one or more of operations 310,311,312,316, 317, and 318 of FIGs. 3A and 3B). For instance, the apparatus can transmit a message (e.g., a request) to cause the activator apparatus to switch from the first transmission mode to the second transmission mode (or vice versa). The apparatus can transmit the message to the activator apparatus (e.g., via the session control unit). For instance, the 5 apparatus can send the message to the session control unit, which can responsively transmit a corresponding configuration message to the activator apparatus. Responsive to receiving the configuration message, the activator apparatus can switch between the transmission modes. 10 In the first transmission mode, the activator apparatus can be configured to transmit a first type of activation signal to the passive device (e.g., as described in relation to operation 308 of FIG. 3A). For instance, the first type of activation signal can comprise a single frequency activation signal and / or a first state indication. The first state indication can cause the passive device, upon receipt of the first state indication, to 15 operate in a first mode corresponding to the first transmission mode and the first receiving mode (e.g., as described in relation to operation 309 of FIG. 3A). In the second transmission mode, the activator apparatus can be configured to transmit a second type of activation signal to the passive device. For instance, the second type of activation signal can comprise a dual-frequency activation signal and / or a second state 20 indication. The second state indication can cause the passive device to operate in a second mode corresponding to the second transmission mode and the second receiving mode (e.g., as described in relation to operation 315 of FIG. 3B). For instance, referring to the earlier example in which it is determined that an expected 25 signal of the first type of signal has not been received from the passive device or that a signal of the first type of signal has been received from the passive device with a signal strength below a first threshold signal strength, the first request message can further comprise a request for an activator apparatus to switch from a first transmission mode to a second transmission mode. Upon receipt of the first request message, the session 30 control apparatus can transmit a configuration message. Upon receipt by the activator apparatus of the configuration message, the activator apparatus is caused to switch from the first transmission mode to the second transmission mode (e.g., as described in relation to operations 310, 311, and 312 of FIG. 3A). 35 Additionally or alternatively, referring to the earlier example in which it is determined that a signal of the second type of signal has been received from the passive device with a signal strength above a second threshold signal strength, the second request message can further comprise a request for an activator apparatus to switch from a second transmission mode to a first transmission mode. Upon receipt of the second request message, the session control apparatus can transmit a configuration message to the 5 activator apparatus. Upon receipt by the activator apparatus of the configuration message, the activator apparatus is caused to switch from the second transmission mode to the first transmission mode (e.g., as described in relation to operations 316, 317, 318 and 303 of FIGs. 3A and 3B). 10 In some implementations, the example method of FIG. 4 can include receiving an initial configuration message (e.g., from the session control apparatus) to cause the apparatus to operate in the first receiving mode (e.g., as described in relation to operation 304 of FIG. 3A). 15 In some implementations, the example method of FIG. 4 can include receiving, from the passive device, data indicative of a capability of the passive device to support operating in a first mode corresponding to the first receiving mode and / or a second mode corresponding to the second receiving mode (e.g., as described in relation to operation 306 of FIG. 3A). The apparatus can responsively communicate the capability 20 information to the session control apparatus. Turning to FIG. 5, a flow diagram of an example method of operating an apparatus (e.g., a session control apparatus no) in an A-IoT system (e.g., the A-IoT system too of FIG. 1) is depicted. 25 At operation S5.1, an occurrence of a trigger condition is determined. For instance, the determination of the occurrence of a trigger condition may be based on a communication received from another apparatus (e.g., a reader apparatus, as described in relation to operations 311 and 317 of FIGs. 3A and 3B). The communication can, for 30 instance, be indicative of a signal strength of a signal received by the reader apparatus from a passive device lower or above a threshold signal strength. At operation S5.2, responsive to the determination that a trigger condition has occurred, a configuration message is transmitted to a reader apparatus to cause the 35 reader apparatus to switch between a first receiving mode and a second receiving mode (e.g., as described in relation to one or more of operations 311,313, 317,318, and 304 of FIGs. 3A and 3B). In the first receiving mode, the reader apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type (e.g., OOK modulation) on a first frequency. In the second receiving mode, the reader apparatus is configured to receive, from the passive 5 device, a second type of signal comprising a backscattered signal using a second modulation type (e.g., BPSK modulation) on a second frequency. In some implementations, the example method of FIG. 5 can include operation S5.3. At operation S5.3, responsive to the determination that a trigger condition has occurred, a 10 configuration message can be transmitted to an activator apparatus to cause the activator apparatus to switch between a first transmission mode and a second transmission mode (e.g., as described in relation to one or more of operations 312,318, and 303 of FIGs. 3A and 3B). 15 In the first transmission mode, the activator apparatus can be configured to transmit a first type of activation signal to the passive device (e.g., as described in relation to operation 308 of FIG. 3A). For instance, the first type of activation signal can comprise a single frequency activation signal and / or a first state indication. The first state indication can cause the passive device, upon receipt of the first state indication, to 20 operate in a first mode corresponding to the first transmission mode and the first receiving mode (e.g., as described in relation to operation 309 of FIG. 3A). In the second transmission mode, the activator apparatus can be configured to transmit a second type of activation signal to the passive device. For instance, the second type of activation signal can comprise a dual-frequency activation signal and / or a second state 25 indication. The second state indication can cause the passive device to operate in a second mode corresponding to the second transmission mode and the second receiving mode (e.g., as described in relation to operation 315 of FIG. 3B). In an example embodiment, a communication maybe received (e.g., from a reader 30 apparatus) indicating that an expected signal of the first type of signal has not been received from the passive device (e.g., by the reader apparatus) or that a signal of the first type of signal has been received (e.g., by the reader apparatus) from the passive device with a signal strength below a first threshold signal strength (e.g., as described in relation to operations 310 and 311 of FIG. 3A). In response, a configuration message 35 can be transmitted (e.g., to the reader apparatus) to cause the reader apparatus to switch from the first receiving mode to the second receiving mode. Additionally or alternatively, a configuration message can be transmitted (e.g., to the activator apparatus) to cause the activator apparatus to switch from the first transmission mode to the second transmission mode. 5 Additionally or alternatively, a communication may be received (e.g., from a reader apparatus) indicating that a signal of the second type of signal has been received from the passive device with a signal strength above a second threshold signal strength (e.g., as described in relation to operations 316 and 317 of FIG. 3B). In response, a configuration message can be transmitted (e.g., to the reader apparatus) to cause the 10 reader apparatus to switch from the second receiving mode to the first receiving mode. Additionally or alternatively, a configuration message can be transmitted (e.g., to the activator apparatus) to cause the activator apparatus to switch from the second transmission mode to the second transmission mode. 15 In some implementations, an initial configuration message can be sent to the reader apparatus to cause the reader apparatus to initially operate in the first receiving mode (e.g., as described in relation to operation 304 of FIG. 3A). Additionally or alternatively, an initial configuration message can be sent to the activator apparatus to cause the activator apparatus to initially operate in the first transmission mode (e.g., as 20 described in relation to operation 303 of FIG. 3A). In some implementations, a communication can be received (e.g., from the passive device via the reader apparatus) indicative of a capability of the passive device to support operating in a first mode corresponding to the first receiving mode and / or a 25 second mode corresponding to the second receiving mode (e.g., as described in relation to operations 306 and 307 of FIG. 3A). The communication can be received responsive to a capability request signal transmitted by the activator apparatus. The activator apparatus can be caused to send the capability request signal, for instance, by an initial configuration message. The capabilities of the passive device can be stored, along with 30 identifying information of the passive device (e.g., a unique identification number). Turning to FIG. 6, a flow diagram of an example method of operating an apparatus (e.g., an activator apparatus 120) in an A-IoT system (e.g., the A-IoT system too of FIG. 1) is depicted. 35 At operation S6.1, it is determined to switch between a first transmission mode and a second transmission mode. For instance, the determination may be based on a communication received e.g.. from the session control apparatus, or from the reader apparatus via the session control apparatus (e.g., as described in relation to operations 5 311,312,317, 318, and 303 of FIGs. 3A and 3B). For instance, the communication can be indicative that a signal strength of a signal received from a passive device lower or above a signal strength threshold. At operation S6.2, responsive to determining to switch between a first transmission 10 mode and a second transmission mode, switching between the first transmission mode and the second transmission mode is caused. In the first transmission mode, the apparatus can be configured to transmit a first type of activation signal to the passive device (e.g., as described in relation to operation 308 of FIG. 3A). For instance, the first type of activation signal can comprise a single frequency activation signal and / or a 15 first state indication. The first state indication can cause the passive device, upon receipt of the first state indication, to operate in a first mode corresponding to the first transmission mode (e.g., as described in relation to operation 309 of FIG. 3A). In the second transmission mode, the apparatus can be configured to transmit a second type of activation signal to the passive device. For instance, the second type of activation 20 signal can comprise a dual-frequency activation signal and / or a second state indication. The second state indication can cause the passive device to operate in a second mode corresponding to the second transmission mode (e.g., as described in relation to operation 315 of FIG. 3B). 25 In some implementations, an initial configuration message can be received (e.g., from the session control apparatus) to cause the apparatus to initially operate in the first transmission mode (e.g., as described in relation to operation 303 of FIG. 3A). In some implementations, responsive to receiving a configuration message (e.g., from 30 the session control apparatus) switching from the first transmission mode to the second transmission mode can be caused (e.g., as described in relation to operations 311, and 312 of FIG. 3A). For instance, the configuration message may be received in response to a determination (e.g., by the reader apparatus and / or the session control apparatus) that an expected signal has not been received from the passive device (e.g., by the 35 reader apparatus) or that a signal has been received from the passive device (e.g., by the reader apparatus) with a signal strength below a first threshold signal strength. Additionally or alternatively, responsive to receiving a configuration message (e.g., from the session control apparatus) switching from the second transmission mode to the first transmission mode can be caused. For instance, the configuration message 5 may be received responsive to a determination (e.g., by the reader apparatus and / or the session control apparatus) indicating that a signal has been received from the passive device (e.g., by the reader device) with a signal strength above a second threshold signal strength. 10 In some implementations, a request can be sent to the passive device to provide data indicative of a capability of the passive device to support operating in a first mode corresponding to the first transmission mode and / or a second mode corresponding to the second transmission mode. The passive device can respond with its capabilities, which can be received by the reader apparatus, and stored by the session control 15 apparatus. FIG. 7 shows an apparatus according to some example embodiments, which may form at least a part of a user equipment or network node. The apparatus may be configured to perform the operations described herein, for example operations described with 20 reference to any disclosed process. The apparatus comprises at least one processor 700 and at least one memory 701 directly or closely connected to the processor. The memory 701 includes at least one random access memory (RAM) 701A and / or at least one read-only memory (ROM) 701B. Processor instructions (software) 705 is stored in the ROM 701B. The apparatus may be connected to a transmitter (TX) and a receiver 25 (RX). The apparatus may, optionally, be connected with a user interface (UI) for instructing the apparatus and / or for outputting data. The at least one processor 700, with the at least one memory7 701 and the instructions 705 are arranged to cause the apparatus to at least perform at least the method, or a part of the method, according to any preceding process, for example as disclosed in relation to the flow diagrams and 30 related features thereof. FIG. 8 shows a non-transitory media 800 according to some embodiments. The non-transitory media 800 is a computer readable storage medium. It maybe e.g., a CD, a DVD, a USB stick, a blue ray disk, etc. The non-transitory media 800 stores 35 instructions that, when executed by at least one processor, cause an apparatus to perform the method of any preceding process, for example as disclosed in relation to the flow diagrams and related features thereof. Names of network elements, protocols, and methods are based on current standards. In 5 other versions or other technologies, the names of these network elements and / or protocols and / or methods may be different, as long as they provide a corresponding functionality. For example, embodiments may be deployed in 2G / 3G / 4G / 5G networks and further generations of 3GPP but also in non-3GPP radio networks such as Wi-Fi. 10 A memory' may be volatile or non-volatile. It may be e.g.. a RAM, a SRAM, a flash memory7, a FPGA block ram, a DCD, a CD, a USB stick, and a blue ray disk. If not otherwise stated or otherwise made clear from the context, the statement that two entities are different means that they perform different functions. It does not 15 necessarily mean that they are based on different hardware. That is, each of the entities described in the present description may be based on a different hardware, or some or all of the entities may be based on the same hard w are. It does not necessarily mean that they are based on different software. That is, each of the entities described in the present description may be based on different software, or some or all of the entities 20 may be based on the same software. Each of the entities described in the present description may be embodied in the cloud. Implementations of any of the above-described blocks, apparatuses, systems, techniques or methods include, as non-limiting examples, implementations as 25 hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof. Some embodiments may be implemented in the cloud. It is to be understood that what is described above is what is presently considered the 30 preferred embodiments. However, it should be noted that the description of the preferred embodiments is given by way of example only and that various modifications may be made without departing from the scope as defined by the appended claims.

Claims

1. An apparatus comprising:means for, responsive to a determination of an occurrence of a trigger5 condition, causing the apparatus to switch between a first receiving mode and a second receiving mode, wherein in the first receiving mode, the apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type on a first frequency, and in the second receiving mode, the apparatus is configured to receive, from the passive device, a second type of signalio comprising a backscattered signal using a second modulation type on a second frequency.

2. The apparatus of claim 1, wherein the first modulation type comprises an on-off keying (OOK) modulation type, and the second modulation type comprises a binary 15 phase-shift keying (BPSK) modulation type.

3. The apparatus of claim 1 or claim 2, further comprising: means for, responsive to the determination of the occurrence of the trigger condition, causing an activator apparatus to switch betw een a first transmission mode 20 in which the activator apparatus transmits a single frequency activation signal to the passive device and a second transmission mode in which the activator apparatus transmits a dual frequency activation signal to the passive device.

4. The apparatus of any one of the preceding claims, wherein causing the 25 apparatus to switch between the first receiving mode and the second receiving mode responsive to determining the occurrence of a trigger condition comprises: determining that an expected signal of the first type of signal has not been received from the passive device or that a signal of the first type of signal has been received from the passive device with a signal strength below a first threshold signal 30 strength;transmitting a first request message comprising a request for the apparatus to switch from the first receiving mode to the second receiving mode; andresponsive to receiving a configuration message responsive to the first request message to switch from the first receiving mode to the second receiving mode,35 switching from the first receiving mode to the second receiving mode.5- The apparatus of any one of the preceding claims, wherein causing the apparatus to switch between the first receiving mode and the second receiving mode responsive to determining the occurrence of a trigger condition comprises:determining that a signal of the second type of signal has been received from the 5 passive device with a signal strength above a second threshold signal strength;transmitting a second request message comprising a request for the apparatus to switch from the second receiving mode to the first receiving mode; andresponsive to receiving a configuration message responsive to the second request message to switch from the second receiving mode to the first receiving mode, io switching from the second receiving mode to the first receiving mode.

6. The apparatus of any one of the preceding claims, further comprising: means for receiving, from the passive device, data indicative of a capability of the passive device to support operating in a first mode corresponding to the first15 receiving mode and / or a second mode corresponding to the second receiving mode.

7. An apparatus comprising:means for, responsive to a determination of an occurrence of a trigger condition, transmitting a configuration message to cause a reader apparatus to switch20 between a first receiving mode and a second receiving mode, wherein in the first receiving mode, the reader apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type on a first frequency, and in the second receiving mode, the reader apparatus is configured to receiv e, from the passive device, a second type of signal comprising a backscattered25 signal using a second modulation type on a second frequency.

8. The apparatus of claim 7, further comprising:means for, responsive to the determination of the occurrence of the trigger condition, transmitting a configuration message to cause an activator apparatus to30 switch between a first transmission mode in which the activator apparatus transmits a single frequency activation signal to the passive device and a second transmission mode in which the activator apparatus transmits a dual frequency activation signal to the passive device.9- The apparatus claim 7 or claim 8, wherein causing the reader apparatus to switch between the first receiving mode and the second receiving mode responsive to determining the occurrence of a trigger condition comprises:receiving a communication indicating that an expected signal of the first type of5 signal received has not been received from the passive device by the reader apparatus or that a signal of the first type of signal has been received from the passive device by the reader apparatus with a signal strength below a first threshold signal strength; and transmitting a configuration message to cause the reader apparatus to switch from the first receiving mode to the second receiving mode.1010. The apparatus of claim 9, further comprising:means for, responsive to receiving the communication indicating that the expected signal of the first type of signal has not been received from the passive device by the reader apparatus or that the signal of the first type of signal has been received15 from the passive device by the reader apparatus with a signal strength below the first threshold signal strength, transmitting a configuration message to cause the activator apparatus to switch from a first transmission mode in which the activator apparatus transmits a single frequency activation signal to a second transmission mode in which the activator apparatus transmits a dual frequency activation signal.2011. The apparatus of any one of claims 7 to 10, wherein causing the readerapparatus to switch between the first receiving mode and the second receiving mode responsive to determining the occurrence of a trigger condition comprises:receiving a communication indicating that a signal of the second type of signal 25 has been received from the passive device by the reader device with a signal strength above a second threshold signal strength; andtransmitting a configuration message to cause the reader device to switch from the second receiving mode to the first receiving mode.30 12. The apparatus of claim 11, further comprising:means for, responsive to receiving the communication indicating that the signal of the second type of signal has been received from the passive device by the reader device with a signal strength above the second threshold signal strength, transmitting a configuration message to cause the activator apparatus to switch from a second35 transmission mode in which the activator apparatus transmits a dual frequencyactivation signal to a first transmission mode in which the activator apparatus transmits a single frequency activation signal.

13. The apparatus of any one of claims 7 to 12, further comprising means for:5 initially configuring the reader apparatus to operate in the first receiving modeand / or initially configuring the activator apparatus to operate in the first transmission mode.

14. The apparatus of any one of claims 7 to 13, further comprising:10 means for receiving data indicative of a capability of the passive device tosupport operating in a first mode corresponding to the first receiving mode and / or a second mode corresponding to the second receiving mode.

15. An apparatus comprising:15 means for, responsive to determining to switch between a first transmissionmode and a second transmission mode, causing the apparatus to switch between a first transmission mode in which the apparatus transmits a first type of activation signal to a passive device and a second transmission mode in which the apparatus transmits a second type of activation signal to the passive device.2016. The apparatus of claim 15, wherein the first type of activation signal comprises a single frequency activation signal and / or a first state indication and wherein the second type of activation signal comprises a dual-frequency activation signal and / or a second state indication, wherein the first state indication causes the passive device to operate25 in a first mode corresponding to the first transmission mode and the second stateindication causes the passive device to operate in a second mode corresponding to the second transmission mode.

17. The apparatus of claim 15 or claim 16, wherein causing the apparatus to switch30 between a first transmission mode and a second transmission mode responsive to determining to switch between the first transmission mode and the second transmission mode comprises:responsive to receiving a configuration message, switching from the first transmission mode to the second transmission mode.3518. The apparatus of any one of claims 15,16, or 17, wherein causing the apparatus to switch between a first transmission mode and a second transmission mode responsive to determining to switch between the first transmission mode and the second transmission mode comprises:5 responsive to receiving a configuration message, switching from the secondtransmission mode to the first transmission mode.

19. The apparatus of any one of claims 15 to 18, further comprising: means for transmitting a request for the passive device to provide data 10 indicative of a capability of the passive device to support operating in a first mode corresponding to the first transmission mode and / or a second mode corresponding to the second transmission mode.

20. An apparatus comprising:15 means for, responsive to receiving an activation signal comprising a first stateindication, reflecting a backscattered signal with a first modulation type on a first frequency; andmeans for, responsive to receiving an activation signal comprising a second state indication, reflecting a backscattered signal with a second modulation type on a 20 second frequency.

21. A method performed by a reader apparatus comprising: responsive to a determination of an occurrence of a trigger condition, causing the apparatus to switch between a first receiving mode and a second receiving mode, 25 wherein in the first receiving mode, the apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type on a first frequency, and in the second receiving mode, the apparatus is configured to receive, from the passive device a second type of signal comprising a backscattered signal using a second modulation type on a second frequency.3022. A method performed by a session control apparatus comprising: responsive to a determination of an occurrence of a trigger condition, transmitting a configuration message to cause the reader apparatus to switch between a first receiving mode and a second receiving mode, wherein in the first receivi ng mode, 35 the reader apparatus is configured to receive, from a passive device, a first type of signal comprising a backscattered signal using a first modulation type on a first frequency,and in the second receiving mode, the reader apparatus is configured to receive, from the passive dev ice a second type of signal comprising a backscattered signal using a second modulation type on a second frequency.5 23. A method performed by a activator apparatus comprising:responsive to determining to switch between a first transmission mode and a second transmission mode, causing the apparatus to switch between a first transmission mode in which the apparatus transmits a first type of activation signal to a passive device and a second transmission mode in which the apparatus transmits a10 second type of activation signal to the passive device.

24. A method performed by a passive device comprising: responsive to receiving an activation signal comprising a first state indication, reflecting a backscattered signal with a first modulation type on a first frequency; and 15 responsive to receiving an activation signal comprising a second stateindication, reflecting a backscattered signal with a second modulation type on a second frequency.Application No: GB2313204.6Examiner:Adam TuckerClaims searched: 1-14, 20-22 &24Date of search: 19 February 2024Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 20&24 US 2007 / 0036237 Al (Semiconductor Energy Lab) See the whole document and in particular Figures 1-3 and paragraphs 2, 3, 8, 9, 55, 57 &66 X 1,2, 4, 6, 20, 21 &24 US 2023 / 0078737 Al (IDAC Holdings Inc.) See the whole document and in particular e.g. Figures 11 &12 and paragraphs 2-4, 88, 98-103, 134, 135, 278-286 &319-325 A - EP 3201839 Bl (X Development LLC) See the whole document A - US 2016 / 0191279 Al (Proton World International) See the whole document. Modulation type is indicated but only a single frequency is used in the transponder response signal A - US 2023 / 0119907 Al (Huawei Tech.) See the whole document. Passive device with network device and relay (activation) device. A,E - WO 2023 / 193192 Al (Oppo Mobile) See the whole document. Passive device that backscatters at first and / or second frequencies A - US 6836468 Bl (Micron Technology Inc.) See the whole document. RFID device configured to switch between active and passive modulation typesX Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB. EP, WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPCH04B; H04L; H04W__________________________________________The following online and other databases have been used in the preparation of this search report SEARCH-PATENT, SEARCH-NPLInternational Classification:Subclass Subgroup Valid From H04L 0027 / 00 01 / 01 / 2006 H04L 0001 / 00 01 / 01 / 2006 H04W 0004 / 80 01 / 01 / 2018 H04B 0001 / 401 01 / 01 / 2015 H04L 0001 / 18 01 / 01 / 2023 H04L 0027 / 02 01 / 01 / 2006 H04L 0027 / 18 01 / 01 / 2006Application No: GB2313204.6 Examiner: Adam TuckerClaims searched: 15-19 &23 Date of search: 23 May 2024Patents Act 1977Further Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance v A 15-19 &23 US 6836468 Bl (O'Toole et al.) See paragraph spanning columns 24 &25, col 26 lines 25-33 and lines 46-54, col 67 lines 3-13 and col 86 lines 41-67 X 15-19 &23 US 2007 / 0036237 Al (Kobayashi et al.) See the whole document and in particular Figures 2 & 3 v A 15-19 &23 US 2014 / 0235165 Al (Restiau et al.) See the whole document and in particular Figure 1 and paragraphs 52-55 and the claims X,E 15-19& 23 WO 2024 / 059413 Al (Qualcomm Inc.) See the whole document and in particular Figure 10 and paragraphs 120-123 X 15-19 & 23 WO 2023 / 005593 Al (Huawei Tech.) see the whole document and in particular paragraph spanning pages 1-2 and penultimate paragraph page 21 A - US 2023 / 0119907 Al (Wu et al.) See the whole documentCategories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:International Classification:Subclass Subgroup Valid From H04L 0027 / 00 01 / 01 / 2006 H04L 0001 / 00 01 / 01 / 2006 H04W 0004 / 80 01 / 01 / 2018 H04B 0001 / 401 01 / 01 / 2015 H04L 0001 / 18 01 / 01 / 2023 H04L 0027 / 02 01 / 01 / 2006 H04L 0027 / 18 01 / 01 / 2006

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