Transmission from zero-energy device to server device

Abstract

There is provided techniques for conveying application-layer information to a server device. A method is performed by a ZED. The method comprises receiving configuration with respect to a trigger condition from the server device. The method comprises harvesting energy for powering-up the ZED for transmission. The method comprises transmitting a payload-less message conveying application-layer information of the ZED to the server device when having harvested sufficient energy for transmitting the payload-less message and upon the trigger condition is fulfilled.

Description

[0001] TRANSMISSION FROM ZERO-ENERGY DEVICE TO SERVER DEVICE

[0002] TECHNICAL FIELD

[0003] Embodiments presented herein relate to a method, a zero-energy device, a computer program, and a computer program product for conveying application-layer information to a server device. Embodiments presented herein further relate to a method, a server device, a computer program, and a computer program product for receiving application-layer information from the zero-energy device.

[0004] BACKGROUND

[0005] In general terms, Zero Energy Devices (ZED) can be defined as ultra-low power small electronic devices that, for example, can be used in Internet of Things (loT) applications. Typically, ZEDs solely rely on energy that is harvested from the surrounding environment through an energy harvester. Non-limiting examples of such energy harvesters are small solar panels, Radio Frequency (RF) detectors, and the like. Often, the harvested energy is stored in small rechargeable batteries, or super-capacitors, or other type of energy storage. However, the most constrained ZEDs are completely passive, and lack even the energy storage, and thus need to consume the energy directly upon being harvested. ZEDs can be used in many applications and typically comprise some type of sensor, e.g., a temperature sensor, as well as some type of wireless communication interface, such as a radio interface, for offloading the sensor readings.

[0006] ZEDs can be used in a variety of environments and for many different purposes, ranging from warehouse inventory to infrastructure monitoring, such as building and bridges, to in-body implants. Specifically, in infrastructure monitoring and in-body implants applications, ZEDs are usually powered though RF signals, like frequency modulation (FM) radio signals or televisions signals, as such RF signals are widely available and require little overhead.

[0007] It goes without saying that it is desirable to design ZEDs that consume as little energy as possible to fulfill their intended purpose. For this reason, extremely constrained ZEDs have been constructed that are able to offload sensor readings using backscatter communication. Backscatter is an ultra-low power technology that allows constrained devices to communicate information via radio interface consuming powers in the order of microWatts. Generally, a backscatter system needs a backscatter tag (equipped with an RF switch), a carrier emitter, and a receiver. The carrier emitter generates some type of signal, such as a sine tone, that is reflected by the backscatter tag. The RF switch is used for encoding information in the reflected signal, e.g., to report a sensor reading, thus producing a backscattered message. Finally, the receiver receives and decodes the backscattered message. In such communication systems, a tag sends a message to a reader without generating any RF wave. It backscatters ambient waves generated by an external source such as a television tower, a radio station, or other wireless frequencies. Further details on zero-energy loT concepts are disclosed in the technical report 3GPP TR 38.838, "Study on XR (Extended Reality) evaluations for NR”, version 17.0.0. This technical report describes four network topologies to support ZEDs, as well as a categorization into three device classes, based on the energy storage characteristics and power consumption. loT devices may generate verbose and possibly redundant data, depending on their data models and application specific protocols. Transmission of such data is particularly counterproductive for ZEDs due to their intermittent nature and severe energy constraints. For instance, if the transmitted payload is too big, the ZED might not be possible to transmit the entire payload before the ZED runs out of energy. Additionally, the lifecycle management of loT devices usually mandates firmware updates to change device characteristics, e.g., change data model, or formatting of the payload. However, the time it takes for such firmware updates to be provisioned to the ZED might exceed the operational time of the ZED.

[0008] Hence, there is a need for further reductions in the energy consumption of ZEDs.

[0009] SUMMARY

[0010] An object of embodiments herein is to address the above issues by reducing the energy consumption of ZEDs when communicating with a server device.

[0011] A particular object is to enable ZEDs to use as little energy as possible for conveying application-layer information to a server device.

[0012] According to a first aspect there is presented a method for conveying application-layer information to a server device. The method is performed by a ZED. The method comprises receiving configuration with respect to a trigger condition from the server device. The method comprises harvesting energy for powering-up the ZED for transmission. The method comprises transmitting a payload-less message conveying application-layer information of the ZED to the server device when having harvested sufficient energy for transmitting the payloadless message and upon the trigger condition is fulfilled.

[0013] According to a second aspect there is presented a ZED for conveying application-layer information to a server device. The ZED comprises processing circuitry. The processing circuitry is configured to cause the ZED to receive configuration with respect to a trigger condition from the server device. The processing circuitry is configured to cause the ZED to harvest energy for powering-up the ZED for transmission. The processing circuitry is configured to cause the ZED to transmit a payload-less message conveying application-layer information of the ZED to the server device when having harvested sufficient energy for transmitting the payloadless message and upon the trigger condition is fulfilled.

[0014] According to a third aspect there is presented a computer program for conveying application-layer information to a server device. The computer program comprises computer code which, when run on processing circuitry of a ZED, causes the ZED to perform actions. One action comprises the ZED to receive configuration with respect to a trigger condition from the server device. One action comprises the ZED to harvest energy for powering-up the ZED for transmission. One action comprises the ZED to transmit a payload-less message conveying applicationlayer information of the ZED to the server device when having harvested sufficient energy for transmitting the payload-less message and upon the trigger condition is fulfilled.

[0015] According to a fourth aspect there is presented a method for receiving application-layer information from a ZED. The method is performed by a server device. The method comprises providing configuration with respect to a trigger condition to the ZED. The method comprises receiving a payload-less message from the ZED. The method comprises extracting the application-layer information from the payload-less message by comparing reception of the payload-less message to the trigger condition.

[0016] According to a fifth aspect there is presented a server device for receiving application-layer information from a ZED. The server device comprises processing circuitry. The processing circuitry is configured to cause the server device to provide configuration with respect to a trigger condition to the ZED. The processing circuitry is configured to cause the server device to receive a payload-less message from the ZED. The processing circuitry is configured to cause the server device to extract the application-layer information from the payload-less message by comparing reception of the payload-less message to the trigger condition.

[0017] According to a sixth aspect there is presented a computer program for receiving application-layer information from a ZED. The computer program comprises computer code which, when run on processing circuitry of a server device, causes the server device to perform actions. One action comprises the server device to provide configuration with respect to a trigger condition to the ZED. One action comprises the server device to receive a payload-less message from the ZED. One action comprises the server device to extract the application-layer information from the payload-less message by comparing reception of the payload-less message to the trigger condition.

[0018] According to a seventh aspect there is presented a computer program product comprising a computer program according to at least one of the third aspect and the sixth aspect and a computer readable storage medium on which the computer program is stored. The computer readable storage medium could be a non-transitory computer readable storage medium.

[0019] Advantageously, these aspects enable the ZED to convey information without transmitting any payload.

[0020] Advantageously, these aspects enable the operational time of the ZED to be prolonged (i.e., enhancing the battery life of the ZED).

[0021] Advantageously, these aspects enable semantics of sensed information to be inferred from ZEDs with minimal overhead.

[0022] Advantageously, these aspects enable the hardware construction of ZEDs to be simplified, enabling the ZED to be cheaper yet more energy efficient. Advantageously, these aspects enable the energy harvester to become the sensor itself, hence not requiring any dedicated sensor (and associated data buffer) to be mounted in the ZED.

[0023] Advantageously, these aspects enable firmware updates, concerning simple data models and encodings, to be provided to the ZED over the air through a wireless network with minimal overhead.

[0024] Advantageously, these aspects enable the functionality of the server device to be simplified, as it does not need to be configured for payload parsing.

[0025] Advantageously, these aspects enable existing nodes in the network structure to be utilized for critical tasks, e.g., infrastructure monitoring.

[0026] Other objectives, features and advantages of the enclosed embodiments will be apparent from the following detailed disclosure, from the attached dependent claims as well as from the drawings.

[0027] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / an / the element, apparatus, component, means, module, step, etc." are to be interpreted openly as referring to at least one instance of the element, apparatus, component, means, module, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The inventive concept is now described, by way of example, with reference to the accompanying drawings, in which:

[0030] Fig. 1 is a schematic diagram illustrating a network according to embodiments;

[0031] Fig. 2 is a block diagram of a ZED according to an embodiment;

[0032] Fig. 3 is a block diagram of a server device according to an embodiment;

[0033] Figs. 4 and 5 are flowcharts of methods according to embodiments;

[0034] Fig. 6 is a signaling diagram of a method according to an embodiment;

[0035] Fig. 7 is a schematic diagram showing structural units of a ZED according to an embodiment;

[0036] Fig. 8 is a schematic diagram showing structural units of a server device according to an embodiment; and

[0037] Fig. 9 shows one example of a computer program product comprising computer readable means according to an embodiment. DETAILED DESCRIPTION

[0038] The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the inventive concept are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like elements throughout the description. Any step or feature illustrated by dashed lines should be regarded as optional.

[0039] Fig. 1 is a schematic diagram illustrating a network 100 where embodiments presented herein can be applied. The network 100 comprises ZEDs 110, illustrated as belonging to two set of ZEDs 130a, 130b, being operatively connected to a server device 120 for the ZEDs 110 to convey application-layer information to the server device 120 and for the server device 120 to configure the ZEDs 110. The server device 120 can be located, or provided, within a network node 140, such as a gNB, in an access network 150, in a core network 160, or in a data network 170, such as in an edge node or a cloud virtual machine within a datacenter. It is assumed that at least the connection between the ZEs 110 and the network node 140 is wireless.

[0040] A block diagram of a ZED is provided in Fig. 2. The ZED 200 comprises an energy harvester block 210, a transceiver block 220, and an (optional) sensor block 230. Generally, the energy harvester block 210 is configured to harvest energy so as to power the transceiver block 220. The transceiver block 220 is configured to, when having sufficient energy, convey application-layer information to the server device 120 and receive configuration from the server device 120. As will be further disclosed below, the application-layer information as conveyed by the transceiver block 220 might be acquired by either the sensor block 230 or the energy harvester block 210 itself. In the latter case there is no need for the ZED 200 to comprise a dedicated sensor block 230. The ZED 110 needs to harvest sufficient energy in order to convey application-layer information to the server device 120 and to receive configuration from the server device 120. This should be achieved with as little energy consumption of the ZED 110 as possible. The operations of the energy harvest block 210, the transceiver block 220, and the sensor block 230 are controlled by a microcontroller embedded in the ZED 200 (not shown). The ZED 110 needs to harvest sufficient energy in order to convey application-layer information to the server device 120 and to receive configuration from the server device 120. This should be achieved with as little energy consumption of the ZED 110 as possible.

[0041] A block diagram of a server device is provided in Fig. 3. The server device 300 comprises a transceiver block 310, an information extraction block 320, and an (optional) application function module 330. Generally, the transceiver block 310 is configured to receive messages from the ZED 200 and to provide configuration to the ZED 200. In this respect, messages as received from the ZED 200 are processed by the information extraction block 320, and the application-layer information extracted therefrom can be provided to the application function module 330 for further processing, as will be further disclosed below. The operations of the transceiver block 310, the information extraction block 320, and the application function 330 are controlled by a microcontroller embedded in the server device 300 (not shown).

[0042] Reference is now made to Fig. 4 illustrating a method for conveying application-layer information to a server device 120, 300, as performed by the ZED 110, 200 according to an embodiment.

[0043] S106: The ZED 110, 200 receives configuration with respect to a trigger condition from the server device 120, 300.

[0044] S108: The ZED 110, 200 harvests energy for powering-up the ZED 110, 200 for transmission.

[0045] S112: The ZED 110, 200 transmits a payload-less message conveying application-layer information of the ZED 110, 200 to the server device 120, 300 when having harvested sufficient energy for transmitting the payload-less message and upon the trigger condition being fulfilled.

[0046] In this way, the ZED is able to convey meaningful application-layer information without transmitting any heavy pay load.

[0047] Embodiments relating to further details of conveying application-layer information to a server device 120, 300, 800 as performed by the ZED 110, 200 will now be disclosed with continued reference to Fig. 4.

[0048] There could be different examples of payload-less messages. In some non-limiting examples, the payload-less message is a heartbeat message, a ping message or a beacon message.

[0049] As will be further disclosed below, the ZED can indicate if it has the capability to convey application-layer information with semantic meaning. Therefore, in some embodiments, the ZED 110, 200 is configured to perform (optional) step S102.

[0050] S102: The ZED 110, 200 indicates, to the server device 120, 300, a capability of the ZED 110, 200 to convey application-layer information with semantic meaning.

[0051] As disclosed above, the ZED 110, 200 in step S112 transmits a payload-less message conveying applicationlayer information of the ZED 110, 200. In some aspects, the application-layer information pertains to sensor data as collected by the ZED 110, 200. Therefore, Therefore, in some embodiments, the ZED 110, 200 is configured to perform (optional) step S110.

[0052] S110: The ZED 110, 200 collects sensor data, wherein information pertaining to the sensor data is conveyed as the application-layer information.

[0053] There can be different ways for the ZED to collect the sensor data in step S110. In some aspects, the ZED is without any dedicated sensor. This is because the application-layer information can be implicitly conveyed by the energy harvester through the ZED when a transmission occurs. That is, in some embodiments, the ZED 110, 200 comprises an energy harvester 210 for harvesting the energy, and the sensor data is collected by the energy harvester 210. This allows the ZED to use the energy harvester as an implicit sensor, enabling the ZEDs to have a simple construction and thus further improving the energy efficiency.

[0054] In some aspects, the data is collected using dedicated sensor. That is, in some embodiments, the ZED 110, 200 comprises a sensor 230, and the sensor data is collected by the sensor 230. This might allow more specific sensor data to be collected than if using the energy harvester 210 for collecting the sensor data.

[0055] In some aspects, the ZED sends the payload-less message as soon as the ZED has harvested enough energy, typically the energy needed to power up the embedded microcontroller. That is, in some embodiments, according to the trigger condition, the payload-less message is to be transmitted as soon as the ZED 110, 200 has harvested the sufficient energy for transmitting the payload-less message. In this case the amount of harvested energy thus has an impact over how often payload-less messages are transmitted. As will be further disclosed below, the server device can, by means of tracking the frequency of occurrence of the payload-less messages, extract application-layer information as conveyed by the ZED.

[0056] In some aspects, the ZED refrains from any transmission, if no anomaly is detected at the ZED. For example, the microcontroller in the ZED might be configured to decide whether sensor readings are normal or not, and only invoke the backscattering (i.e., the conveying of application-layer information from the the transceiver block 220) in case any type of anomaly is detected. Consequently, the ZED preserves energy and avoids polluting the spectrum with non-meaningful information. That is, in some embodiments, according to the trigger condition, the payload-less message is to be transmitted when the sensor data exceeds a threshold. In some non-limiting examples, the threshold is defined by at least one of a temperature value, a pressure value, a vibration intensity value, a light brightness level.

[0057] The ZED can also use different patterns of payload-less messages for conveying different sensor reading values. In particular, in some embodiments, the application-layer information is conveyed by the ZED 110, 200 altering inter-transmission times between subsequently transmitted payload-less messages.

[0058] In some aspects, and as will be disclosed in further detail below, the server device configures the ZED in terms of which type of application-layer information that is to be conveyed by the ZED. Hence, in some embodiments, the ZED 110, 200 is configured to perform (optional) step S104.

[0059] S104: The ZED 110, 200 receives information from the server device 120, 300 regarding which type of application-layer information that is to be conveyed by the ZED 110, 200, and the application-layer information as conveyed is of this type of application-layer information. The specification of the type of application-layer information can be regarded as defining the semantics of the application-layer information, and hence the information from the server device about the which type of application-layer information that is to be conveyed by the ZED can be regarded as defining the semantics to be used by the ZED when conveying the application-layer information. As a non-limiting and illustrative example, a software component in the ZED is configured to map specific signals as received from the server device via the network node into actionable functions, such as a software functions. For example, the reception of a specific standard random-access channel (RACH) preamble might trigger this software component to invoke a function invert_warning_preamble() by means of which the ZED inverts the semantic of a particular message.

[0060] Reference is now made to Fig. 5 illustrating a method for receiving application-layer information from a ZED 110, 200 as performed by the server device 120, 300 according to an embodiment.

[0061] S204: The server device 120, 300 provides configuration with respect to a trigger condition to the ZED 110, 200.

[0062] S204: The server device 120, 300 receives a payload-less message from the ZED 110, 200.

[0063] S204: The server device 120, 300 extracts the application-layer information from the payload-less message by comparing reception of the payload-less message to the trigger condition.

[0064] In this way the server device is able to detect the activity of the ZED at the same time as the ZED is allowed to use as little energy as possible for conveying the application-layer information to the server device.

[0065] Embodiments relating to further details of receiving application-layer information from a ZED 110, 200 as performed by the server device 120, 300 will now be disclosed with continued reference to Fig. 5.

[0066] As disclosed above, the server device provides configuration to the ZED. One purpose of this configuration is to improve spectrum efficiency, in addition to reducing the energy consumption of the ZEDs. Further, this configuration should be provided to the ZEDs in a lightweight manner. For example, the configuration could pertain to basic transmission characteristics, such as the maximum amount of transmissions per day, or a change of the identifier associated with a given ZED. In this way the server device might reconfigure the semantics of the transmissions from the ZEDs so as to optimize spectrum utilization.

[0067] For example, in an effort to reduce the probability of interference or contention, the server device might be configured to instruct each set of ZEDs to perform transmissions on a separate radio channel.

[0068] For example, in an effort to reduce the burden of heavy and complicated firmware updates over the air, the device might be configured to instruct the ZEDs regarding the semantics to be used by the ZEDs when conveying the application-layer information. Therefore, in some embodiments, the server device 120, 300 is configured to perform (optional) step S202. S202: The server device 120, 300 provides information to the ZED 110, 200 regarding which type of applicationlayer information that is to be conveyed by the ZED 110, 200.

[0069] For example, the configuration may pertain to the semantics to be used by the ZEDs for conveying an “all-ok" message and an "alarm” message, respectively. In this respect, more capable ZEDs may use different radio channels to convey different information, whilst less capable ZED may use different physical (PHY) layer resources (or medium access control (MAC) resources) to convey different information.

[0070] In some examples, the server device configures the ZEDs based on different carriers. For example, one set of frequency bands, carriers, or subcarriers can be used configure one set of instructions e.g., the configuration for "all-ok” messages, and other set of frequency bands, carriers, or subcarriers can be used configure one set of instructions e.g., the configuration for "alarm” messages. This principle can be extended to more than two frequency bands, carriers, or subcarriers depending on the defined semantics. Generally, in some embodiments, the information in step S202 is provided in carriers, sub-carriers, or frequency-intervals with separate instructions per carrier, sub-carrier, or frequency interval.

[0071] Considering the example with two frequency bands, carriers, or subcarriers (for two semantics types). Then the ZEDs should be configured for operational capabilities for these two frequency bands, carriers, or subcarriers. For this purpose, in one example, each ZED has hardware, such as antennas, circuitry, etc. for transmitting or receiving in both these two frequency bands, carriers, or subcarriers. In another example, each ZED has hardware that can be tuned for transmit or reception in each of the frequency bands, carriers, or subcarriers one at a time. For e.g., at time T1 , the antenna is tuned with a first impedance enabling the antenna to transmit or receive in a first frequency band, carrier, or subcarrier, and at time T2, the antenna is tuned with a second impedance enabling the antenna to transmit or receive in a second frequency band, carrier, or subcarrier.

[0072] In some examples, the server device configures the ZEDs to convey the application-layer information using, e.g., two or more set of preambles (e.g., RACH preamble), transmission using two or more physical uplink control channel (PUCCH) formats, transmission using two or more set of physical uplink shared channel (PUSCH) formats, two or more sets of MAC control elements (CEs) and / or, two or more sets PPHY layer or network layer messages.

[0073] In some examples, the ZEDs indicate their capabilities for conveying application-layer information during transmission of identifiers at the beginning of the network registration procedure. Here, each ZED may indicate an identifier such as a Subscription Permanent Identifier (SUPI) or a Subscription Concealed Identifier (SUPI), or the like.

[0074] In some aspects, the server device is configured to estimate the extent of the energy as harvested by the ZED. Such an estimate can, among many things, be used to detect anomalies. For example, an increasing number of messages received from a ZED embedded in a concrete structure may signal excessive vibration of the concrete structure, where the excessive vibration causes the energy harvesting in the ZED to increase. For example, a complete lack of reception of messages from a ZED may signal failure of the ZED.

[0075] In some aspects, the server device is configured to build a statistical distribution of transmissions as received from each ZED. For example, the server device might timestamp all received transmissions from a ZED and associate the time with a unique identifier associated with the specific ZED. Therefore, in some embodiments, the server device 120, 300 is configured to perform (optional) step S210.

[0076] S210: The server device 120, 300 associates the payload-less message with a timestamp and an identifier of the ZED 110, 200.

[0077] The server device might then build a statistical model based on some metrics, e.g., interarrival time or number of packets per time unit, to define the normal behavior of the specific ZED, based on the energy conditions of the surrounding environment. That is, in some embodiments, the statistics are of message interarrival times or number or received messages per time unit. Such distribution can, by the server device, be used to individuate anomalies in the physical object, or structure, hosting the ZED. Hence, in some embodiments, the server device 120, 300 is configured to perform (optional) step S212.

[0078] S212: The server device 120, 300 determines that the payload-less message indicates an anomaly in case statistics of the payload-less message as derivable from the timestamp deviates more than a threshold value from other timestamped data as available to the server device 120, 300.

[0079] There can be different types of such other timestamped data. In some embodiments, this other timestamped data is timestamped previously received payload-less messages from the ZED 110, 200 or timestamped sensor data. For example, the timestamped sensor data can be sensor data received from a camera, some dedicated senor device, etc.

[0080] An anomaly may be detected in several ways, such as with a machine learning model rather than a simple arithmetic expression.

[0081] As a non-limiting and illustrative example, for a ZED mounted within a bridge structure (or a building wall), one transmission per day from the ZED might be expected since very little energy can be harvested by the ZED in case the bridge (or building wall) is without any vibrations. On the other hand, if the bridge (or building wall) starts to vibrate, this causes the ZED to harvest energy faster and thus to increase the frequency, or intensity, of its transmissions. The server device, by detecting such an increase in frequency, or intensity, might deduce a potentially dangerous situation and trigger an alarm to the relevant entity. For example, if the server device estimates that the frequency, or intensity, of transmission has exceeded a predefined threshold, this might trigger the server device to send an alarm signal to an application function that monitors activity of the bridge (or building wall). In some aspects, the server device is configured to assess malfunctioning ZEDs belonging to the same physical structure, e.g., a bridge or a building. In particular, in some embodiments, the ZED 110, 200 is associated with a set of ZEDs 130a and the server device 120, 300 is configured to perform (optional) step S216.

[0082] S214: The server device 120, 300 determines that the ZED 110, 200 is malfunctioning by in case statistics of the payload-less message as derivable from the timestamp deviate more than a threshold from statistics of payloadless messages with matching timestamps and received from the set of ZEDs 130a.

[0083] For example, assume that most of the ZEDs in a set of ZEDs installed in one of the pillars of a bridge transmit with similar interarrival time, whilst one of the ZEDs in the same set of ZEDs transmits with a much longer interarrival time (or at least with some outlier interarrival times). Based on this, the server device might deduce that this one of the ZEDs is malfunctioning.

[0084] As a further non-limiting and illustrative example, for a ZED mounted within a bridge structure, the transmissions from the ZED can, by the server device, be used to estimate the traffic intensity on the bridge. In further detail, as the number of vehicles transiting over the bridge increases, the amount of vibrations within the bridge will also increase. In turn, this cases the frequency, or intensity, of the transmissions from the ZED to increase. In particular, in some embodiments, the server device 120, 300 comprises an application function module 330 and is configured to perform (optional) step S216.

[0085] S216: The server device 120, 300 uses the application-layer information as input to the application function module 330.

[0086] In view of the above, the server device might be trained to distinguish between a potential dangerous situation and a normal increase in traffic. This is possible since the statistics of transmissions from the ZEDs during potentially dangerous situations is different from the statistics of transmissions from the ZEDs during a normal increase in traffic, for example because the former shows a more erratic behavior and even higher frequency, or intensity, of transmissions than the latter.

[0087] In some aspects, the application-layer information from the ZED is used together with some other type of information to assess potentially dangerous situations. The application-layer information can in this way thus be used for a secondary purpose. As a non-limiting and illustrative example, the server device might in addition to having access to the application-layer information from the ZED also have access to other type of sensor data, such as images from a video surveillance system. For example, by receiving an excessive number of transmissions from a ZED mounted within a bridge structure, whilst the video surveillance system shows no traffic on the bridge, may trigger an anomaly to be detected. One particular embodiment for conveying application-layer information from a ZED to a server device based on at least some of the above disclosed embodiments will now be disclosed in detail with reference to the signaling diagram of Fig. 6.

[0088] S300: The server device obtains statistics of ZED transmissions.

[0089] Step S300 needs only to be performed in case the server device will not compile statistics, as in step S305.

[0090] S301: The server device provides configuration with respect to a trigger condition to the ZED.

[0091] S302: The ZED harvests energy for powering-up the ZED for transmission.

[0092] S303: The ZED transmits a payload-less message conveying application-layer information of the ZED to the server device when having harvested sufficient energy for transmitting the payload-less message and upon the trigger condition being fulfilled.

[0093] S304: The server device extracts the application-layer information from the payload-less message, adds a timestamp, and stores the thus timestamped application-layer information and an identifier of the ZED.

[0094] Steps S302, S303, and S304 can be repeated for the server device to on-the-fly build statistics of transmissions from the ZED. Alternatively, the server device might already have been provided with statistics, as for example generated by a model, other ZEDs, etc.

[0095] S305: The server device compiles statistics of the transmissions from the ZED based on the stored applicationlayer information for the ZED.

[0096] Step S305 needs only to be performed in case the server device has not already been provided with the statistics, as in step S300.

[0097] S306: The ZED harvests energy for powering-up the ZED for transmission.

[0098] S307: The ZED transmits a payload-less message conveying application-layer information of the ZED to the server device when having harvested sufficient energy for transmitting the payload-less message and upon the trigger condition being fulfilled.

[0099] S308: The server device determining whether the payload-less message in step S307 indicates an anomaly or not by comparing statistics derivable from the payload-less message in step S307 to the statistics compiled in step S305 (or otherwise provided to the server device).

[0100] Step S306 is entered again in case no anomaly was detected. Step S309 is entered in case an anomaly was detected. S309: The server device issues an alarm message to the relevant entity.

[0101] Fig. 7 schematically illustrates, in terms of a number of structural units, the components of a ZED 700 according to an embodiment. Processing circuitry 710 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 910a (as in Fig. 9), e.g. in the form of a storage medium 730. The processing circuitry 710 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0102] Particularly, the processing circuitry 710 is configured to cause the ZED 700 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 730 may store the set of operations, and the processing circuitry 710 may be configured to retrieve the set of operations from the storage medium 730 to cause the ZED 700 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 710 is thereby arranged to execute methods as herein disclosed.

[0103] The storage medium 730 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0104] The ZED 700 may further comprise a communications (comm.) interface 720 for communications with other entities, functions, nodes, and devices, as in Fig. 1. As such the communications interface 720 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0105] The processing circuitry 710 controls the general operation of the ZED 700 e.g. by sending data and control signals to the communications interface 720 and the storage medium 730, by receiving data and reports from the communications interface 720, and by retrieving data and instructions from the storage medium 730. Other components, as well as the related functionality, of the ZED 700 are omitted in order not to obscure the concepts presented herein.

[0106] Fig. 8 schematically illustrates, in terms of a number of structural units, the components of a server device 800 according to an embodiment. Processing circuitry 810 is provided using any combination of one or more of a suitable central processing unit (CPU), multiprocessor, microcontroller, digital signal processor (DSP), etc., capable of executing software instructions stored in a computer program product 910b (as in Fig. 9), e.g. in the form of a storage medium 830. The processing circuitry 810 may further be provided as at least one application specific integrated circuit (ASIC), or field programmable gate array (FPGA).

[0107] Particularly, the processing circuitry 810 is configured to cause the server device 800 to perform a set of operations, or steps, as disclosed above. For example, the storage medium 830 may store the set of operations, and the processing circuitry 810 may be configured to retrieve the set of operations from the storage medium 830 to cause the server device 800 to perform the set of operations. The set of operations may be provided as a set of executable instructions. Thus the processing circuitry 810 is thereby arranged to execute methods as herein disclosed.

[0108] The storage medium 830 may also comprise persistent storage, which, for example, can be any single one or combination of magnetic memory, optical memory, solid state memory or even remotely mounted memory.

[0109] The server device 800 may further comprise a communications interface 820 for communications with other entities, functions, nodes, and devices, as in Fig. 1. As such the communications interface 820 may comprise one or more transmitters and receivers, comprising analogue and digital components.

[0110] The processing circuitry 810 controls the general operation of the server device 800 e.g. by sending data and control signals to the communications interface 820 and the storage medium 830, by receiving data and reports from the communications interface 820, and by retrieving data and instructions from the storage medium 830. Other components, as well as the related functionality, of the server device 800 are omitted in order not to obscure the concepts presented herein.

[0111] The server device 120, 300, 800 may be provided as a standalone device or as a part of at least one further device. For example, the server device 120, 300, 800 may be provided in a network node 140 in the access network 150, the core network 160, or in the data network 170. Alternatively, functionality of the server device 120, 300, 800 may be distributed between at least two devices, or nodes. These at least two nodes, or devices, may either be part of the same network part (such as the access network 150, the core network 160, or the data network 170) or may be spread between at least two such network parts. In general terms, instructions that are required to be performed in real time may be performed in a device, or node, operatively closer to the cell than instructions that are not required to be performed in real time. Thus, a first portion of the instructions performed by the server device 120, 300, 800 may be executed in a first device, and a second portion of the instructions performed by the server device 120, 300, 800 may be executed in a second device; the herein disclosed embodiments are not limited to any particular number of devices on which the instructions performed by the server device 120, 300, 800 may be executed. Hence, the methods according to the herein disclosed embodiments are suitable to be performed by a server device 120, 300, 800 residing in a cloud computational environment. Therefore, although a single processing circuitry 810 is illustrated in Fig. 8 the processing circuitry 810 may be distributed among a plurality of devices, or nodes. The same applies to the computer program 920b of Fig. 9.

[0112] Fig. 9 shows one example of a computer program product 910a, 910b comprising computer readable means 930. On this computer readable means 930, a computer program 920a can be stored, which computer program 920a can cause the processing circuitry 710 and thereto operatively coupled entities and devices, such as the communications interface 720 and the storage medium 730, to execute methods according to embodiments described herein. The computer program 920a and / or computer program product 910a may thus provide means for performing any steps of the ZED 110, 200, 700 as herein disclosed. On this computer readable means 930, a computer program 920b can be stored, which computer program 920b can cause the processing circuitry 810 and thereto operatively coupled entities and devices, such as the communications interface 820 and the storage medium 830, to execute methods according to embodiments described herein. The computer program 920b and / or computer program product 910b may thus provide means for performing any steps of the server device 120, 300, 800 as herein disclosed.

[0113] In the example of Fig. 9, the computer program product 910a, 910b is illustrated as an optical disc, such as a CD (compact disc) or a DVD (digital versatile disc) or a Blu-Ray disc. The computer program product 910a, 910b could also be embodied as a memory, such as a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM), or an electrically erasable programmable read-only memory (EEPROM) and more particularly as a non-volatile storage medium of a device in an external memory such as a USB (Universal Serial Bus) memory or a Flash memory, such as a compact Flash memory. Thus, while the computer program 920a, 920b is here schematically shown as a track on the depicted optical disk, the computer program 920a, 920b can be stored in any way which is suitable for the computer program product 910a, 910b.

[0114] The inventive concept has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the inventive concept, as defined by the appended patent claims.

Claims

CLAIMS1 . A method for conveying application-layer information to a server device (120, 300, 800), the method being performed by a zero-energy device, ZED (110, 200, 700), the method comprising: receiving (S106) configuration with respect to a trigger condition from the server device (120, 300, 800); harvesting (S108) energy for powering-up the ZED (110, 200, 700) for transmission; and transmitting (S112) a payload-less message conveying application-layer information of the ZED (110, 200, 700) to the server device (120, 300, 800) when having harvested sufficient energy for transmitting the payloadless message and upon the trigger condition being fulfilled.

2. The method according to claim 1 , wherein the method further comprises: collecting (S110) sensor data, wherein information pertaining to the sensor data is conveyed as the application-layer information.

3. The method according to claim 1, wherein the ZED (110, 200, 700) comprises an energy harvester (210) for harvesting the energy, and wherein the sensor data is collected by the energy harvester (210).

4. The method according to claim 1, wherein the ZED (110, 200, 700) comprises a sensor (230), and wherein the sensor data is collected by the sensor (230).

5. The method according to claim 1, wherein, according to the trigger condition, the payload-less message is to be transmitted as soon as the ZED (110, 200, 700) has harvested the sufficient energy for transmitting the payload-less message.

6. The method according to claim 2, wherein, according to the trigger condition, the payload-less message is to be transmitted when the sensor data exceeds a threshold.

7. The method according to claim 6, wherein the threshold is defined by at least one of: a temperature value, a pressure value, a vibration intensity value, a light brightness level.

8. The method according to claim 1, wherein the payload-less message is a heartbeat message, a ping message or a beacon message.

9. The method according to claim 1, wherein the application-layer information is conveyed by the ZED (110, 200, 700) altering inter-transmission times between subsequently transmitted payload-less messages.

10. The method according to claim 1, wherein the method further comprises:indicating (S102), to the server device (120, 300, 800), a capability of the ZED (110, 200, 700) to convey application-layer information with semantic meaning.11 . The method according to claim 1 , wherein the method further comprises: receiving (S104) information from the server device (120, 300, 800) regarding which type of applicationlayer information that is to be conveyed by the ZED (110, 200, 700), and wherein the application-layer information as conveyed is of said type of application-layer information.

12. A method for receiving application-layer information from a zero-energy device, ZED (110, 200, 700), the method being performed by a server device (120, 300, 800), the method comprising: providing (S204) configuration with respect to a trigger condition to the ZED (110, 200, 700); receiving (S206) a payload-less message from the ZED (110, 200, 700); and extracting (S208) the application-layer information from the payload-less message by comparing reception of the payload-less message to the trigger condition.

13. The method according to claim 12, wherein the method further comprises: associating (S210) the payload-less message with a timestamp and an identifier of the ZED (110, 200, 700).

14. The method according to claim 13, wherein the method further comprises: determining (S212) that the payload-less message indicates an anomaly in case statistics of the payloadless message as derivable from the timestamp deviates more than a threshold value from other timestamped data as available to the server device (120, 300, 800).

15. The method according to claim 14, wherein said other timestamped data is timestamped previously received payload-less messages from the ZED (110, 200, 700) or timestamped sensor data.

16. The method according to claim 13 or 14, wherein the ZED (110, 200, 700) is associated with a set of ZEDs (130a), and wherein the method further comprises: determining (S214) that the ZED (110, 200, 700) is malfunctioning by in case statistics of the payload-less message as derivable from the timestamp deviate more than a threshold from statistics of payload-less messages with matching timestamps and received from the set of ZEDs (130a).

17. The method according to claim 14, 15 or 16, wherein the statistics are of message interarrival times or number or received messages per time unit.

18. The method according to claim 12, wherein the server device (120, 300, 800) comprises an application function module (330), and wherein the method further comprises: using (S216) the application-layer information as input to the application function module (330).

19. The method according to claim 12, wherein the method further comprises: providing (S202) information to the ZED (110, 200, 700) regarding which type of application-layer information that is to be conveyed by the ZED (110, 200, 700).

20. The method according to claim 12, wherein the information is provided in carriers, sub-carriers, or frequency-intervals with separate instructions per carrier, sub-carrier, or frequency interval.

21. The method according to claim 12, wherein the server device (120, 300, 800) is provided in an access network (150), a core network (160), or a data network (170).

22. A zero-energy device, ZED, (110, 200, 700) for conveying application-layer information to a server device (120, 300, 800), the ZED (110, 200, 700) comprising processing circuitry (710), the processing circuitry being configured to cause the ZED (110, 200, 700) to: receive configuration with respect to a trigger condition from the server device (120, 300, 800); harvest energy for powering-up the ZED (110, 200, 700) for transmission; and transmit a payload-less message conveying application-layer information of the ZED (110, 200, 700) to the server device (120, 300, 800) when having harvested sufficient energy for transmitting the payload-less message and upon the trigger condition being fulfilled.

23. The ZED (110, 200, 700) according to claim 22, further being configured to perform the method according to any of claims 2 to 11.

24. A server device (120, 300, 800) for receiving application-layer information from a zero-energy device, ZED, (110, 200, 700), the server device (120, 300, 800) comprising processing circuitry (810), the processing circuitry being configured to cause the server device (120, 300, 800) to: provide configuration with respect to a trigger condition to the ZED (110, 200, 700); receive a payload-less message from the ZED (110, 200, 700); and extract the application-layer information from the payload-less message by comparing reception of the payload-less message to the trigger condition.

25. The server device (120, 300, 800) according to claim 24, further being configured to perform the method according to any of claims 13 to 20.

26. A computer program (920a) for conveying application-layer information to a server device (120, 300, 800), the computer program comprising computer code which, when run on processing circuitry (710) of a zero-energy device, ZED, (110, 200, 700), causes the ZED (110, 200, 700) to: receive (S106) configuration with respect to a trigger condition from the server device (120, 300, 800); harvest (S108) energy for powering-up the ZED (110, 200, 700) for transmission; and transmit (S112) a payload-less message conveying application-layer information of the ZED (110, 200, 700) to the server device (120, 300, 800) when having harvested sufficient energy for transmitting the payloadless message and upon the trigger condition being fulfilled.

27. A computer program (920b) for receiving application-layer information from a zero-energy device, ZED, (110, 200, 700), the computer program comprising computer code which, when run on processing circuitry (810) of a server device (120, 300, 800), causes the server device (120, 300, 800) to: provide (S204) configuration with respect to a trigger condition to the ZED (110, 200, 700); receive (S206) a payload-less message from the ZED (110, 200, 700); and extract (S208) the application-layer information from the payload-less message by comparing reception of the payload-less message to the trigger condition.

28. A computer program product (910a, 910b) comprising a computer program (920a, 920b) according to at least one of claims 26 and 27, and a computer readable storage medium (930) on which the computer program is stored.

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