Method for transmitting and receiving data in an IoT system

Abstract

Method of transmitting and receiving data (100, 200) with controlled accuracy between a wireless device (1) connected to a wireless network (3) and one or more service platforms (2). The transmission method (100) comprises measuring at least one physical quantity and classifying the measurement datum (Rt) as a standby measurement datum (Ra) if the measurement datum (Rt) is within the reference range (r*) or classifying the measurement datum (Rt) as a transmission measurement datum (Rtx) if the measurement datum (Rt) is outside said reference range (r*), and transmitting the message packet only when, among its component measurement data, the last measurement datum in terms of time is a transmission measurement datum (Rtx). The reception method (200) comprises receiving (S202) a first message packet (Ml), waiting for the reception of a new message packet for a first expected reception time (tpl), wherein, if said new message packet is not received for said first expected reception time (tpl), the method comprises estimating based on a dynamic accuracy value determined in the method the value of a measurement datum for said first expected reception time (tpl) until a second message packet (M2) is received, and replacing the previously estimated values for the expected reception times with the values of the measurement data received with the second message packet associated with the same time instants.

Description

[0001] Method for transmitting and receiving data in an loT system

[0002] TECHNICAL FIELD

[0003] The present invention relates to a method of data transmission by a wireless device connected to a wireless network, in particular an Internet of Things network, connecting the device to one or more service platforms and a method of data reception by a platform connected to a wireless network, in particular an Internet of Things network .

[0004] Furthermore , the present invention relates to a wireless device located within a wireless network, in particular an Internet of Things network, and to an Internet of Things system comprising one or more of said devices . In addition, the present invention relates to a computer product , in particular a computer program, capable of performing the steps of said transmission method and / or said reception method and to a computer-readable medium comprising a program for implementing said methods .

[0005] STATE OF THE ART

[0006] An Internet of Things ( loT ) system is based on an integration between digital and physical components through the use of sensors and actuators . Depending on the applications required, distributed sensors often require short-range or wide-area wireless and battery-operated connections to conveniently connect to data acquisition and processing platforms typically based on a Cloud Computing system (hereinafter simply Cloud) . It is estimated that the global number of connected loT devices can exceed one billion with the progressive improvement of low-power wireless networks in their capacity to manage a large number of devices by extending coverage in both terrestrial and satellite environments.

[0007] Several standards for wireless communications address the issue of energy efficiency for battery-powered sensors. For example, the ZigBee standard is designed for high energy efficiency in short-range wireless communications by allowing a single battery-powered sensor to operate for years without the need to replace or recharge the battery. The 3GPP Narrowband loT (NB loT) standard provides a highly energy efficient solution for wireless communications in networks with a large number of sensors and actuators geographically dispersed over a large area. Various satellite-based systems provide continuous or intermittent radio coverage for loT networks over a wide area (e.g. continental) using different types of typically low Earth orbit (LEO) satellites. As the coverage area of the loT service grows, battery life is an increasingly critical factor in the cost and useful life of the system, for example, the reduction of battery consumption can enable the use of autonomous charging systems based on intermittent sources such as photovoltaic.

[0008] Usually, the radio communication unit of a wireless loT device is the one that consumes the most power in the device. Given a certain wireless loT communication system regardless of the energy efficiency of the radio protocol used (e.g. NB loT) , terrestrial or satellite, the problem arises of how to improve the energy efficiency of the system by reducing the energy use of the radio communication phases increasing the life of the battery and reducing costs. Considering the energy density of the current battery standards as well as special technologies (e.g. nuclear battery) , a similar problem also arises in special loT space applications such as , for example , for deep space exploration probes or micro-satellites ( e . g . Cubesat- type microsatellites ) in which energy savings directly translate into a reduction in the weight and therefore in the costs of the entire system, costs which are strongly linked to launch and commissioning .

[0009] Battery li fe is a key factor in defining the total costs of an loT system, as battery replacement is sometimes impractical or not possible / economically sustainable . In addition, a complete replacement of the device is in many cases expensive due to the installation costs in remote areas .

[0010] To reduce power consumption, loT devices usually rely on limited hardware and software resources , for example , limited data processing resources such as small memories and processors with limited processing capacity and excellent latent state consumption performance ( "deep sleep" state ) , a state in which the device inhibits many of its own functional subunits in order to reduce power consumption .

[0011] An loT device may be provided with a battery charging system such as , for example , small photovoltaic generators or small wind turbines . However, the energy source of these generators is not always constant and predictable .

[0012] Managing the energy budget of the loT device is therefore a key issue to improve the utility of the loT system .

[0013] It is noted that a remote loT device can continuously and regularly measure certain parameters ( e . g . electricity, water, gas , temperature consumption) and can connect according to a predefined time interval with an loT platform via a wireless network . The loT device may also have activation and control capabilities , for example a remote loT wireless device that measures the water level of a tank and controls an actuator that regulates a water flow valve .

[0014] According to a basic operating principle , a local control system of an loT device may establish a transmission command to the radio communication system at regular time intervals (At ) to transmit measurements made by the wireless device to the loT platform . For example , the device can activate radio communication, authenticate and connect to the wireless network by associating with the packet data transmission system, establish a data connection with the platform by sending the measurements , disconnect from the network and deactivate radio communication to conserve battery power by entering a phase called " sleep" . The energy ef ficiency of the system, defined as the amount of time it can operate given a certain battery capacity, would be determined by the amount of energy required for the transmission of each At . It is noted that loT transmission at regular intervals At is not very ef ficient in terms of energy, as an energy consumption is determined for each time interval At in which data is trans ferred, regardless of the change of the measurement in the At with respect to an accuracy necessary for the correct operation of the system .

[0015] US2017 / 0188308A1 discloses a method and apparatus for extending the operational li fe of an loT device . The loT device includes a communication unit configured to transmit a report from a message controller and a power monitor to monitor a backup power level of the battery . A range adj uster controls the timing of the ratio based at least in part on the battery backup power level .

[0016] However, in the system described in this document , during the time intervals when the loT device does not transmit any data, the platform has no possibility to determine possible data values . In addition, the transmission is randomly distributed over time . Therefore , the method of this device cannot be applied when it is necessary to obtain information from the loT device at regular intervals , for example in the case of process control systems or for the measurement of atmospheric temperature or pressure as a function of weather forecast models . In addition, the method described in this prior art document does not allow the control of intermittent transmission intervals based on information contained in the actual data values . Furthermore , this method is not appropriate when the loT device includes actuators that need to be controlled by the cloud platform as there is no way for the platform to control or limit the accuracy and latency of actuator control commands .

[0017] Therefore , it is an obj ect of the present invention to provide a method and device that addresses the problem of managing the energy ef ficiency of battery-powered loT wireless devices . In particular, it is an obj ect of the present invention to provide a method capable of dynamically managing the energy ef ficiency of loT devices with limited processing resources that measure continuously or regularly ( e . g . at defined time intervals ) a certain set of parameters with controllable accuracy within an loT system that requires real-time data at typically regular intervals At . Furthermore , it is an obj ect of the present invention to provide a method capable of managing control and activation actions through actuators . DISCLOSURE OF THE INVENTION

[0018] These obj ects are achieved by a transmission method, by a reception method, by a device , by a system, by a computer product , and by a computer-readable medium according to the claims at the end of the present description .

[0019] In a first aspect of the invention there is provided a method of transmitting data by a wireless device connected to a wireless network, in particular an Internet of Things network, connecting the device to one or more service platforms .

[0020] The method comprises : pre-determining an initial accuracy value between the device and the platform for at least one physical quantity measured by the wireless device ( 1 ) , wherein the initial accuracy value is previously communicated by the device to the platform or vice versa, or negotiated between the device and the platform, in particular according to the needs of the type of service ; dividing a scale of the values of the physical quantity detected into ranges of disj oint and consecutive values of homogeneous si ze and dependent on the initial accuracy value ; measuring the physical quantity by the wireless device for several time instants and detecting a corresponding plurality of measurement data of said physical quantity by means of at least one sensor ; for each time instant , determining the range of values within which each measurement datum is located and comparing the measurement datum detected at a certain time with a reference range relating to the measurement datum detected at the previous time instant ; classifying the measurement datum as a standby measurement datum if the measurement datum is within the reference range or classifying the measurement datum as a transmission measurement datum if the measurement datum is outside said reference range, preparing a message packet comprising one or more measurement data detected at different time points; and transmitting the message packet via a communication unit to the platform connected to the network, wherein the message packet is only transmitted when, among its component measurement data, the last measurement datum in terms of time is a transmission measurement datum and wherein the message packet is transmitted to the platform together with a subsequent accuracy value to be applied to the measurement data detected at times subsequent to that of transmission .

[0021] In particular, the method comprises: pre-determining an initial accuracy value between the device and the platform for at least one physical quantity measured by the wireless device, wherein the initial accuracy value is previously communicated by the device to the platform or vice versa, or negotiated between the device and the platform; measuring the physical quantity through the wireless device for several consecutive time instants (tl, t2, t3,...tn) and detecting a corresponding plurality of measurement data (Rtl, Rt2, Rt3,...Rtn) of said physical quantity by means of at least one sensor; for each time instant (tl, t2, t3,...tn) determining a range of values (rl, r2, r3,...rm) within which each measurement datum (Rtl, Rt2, Rt3,...Rtn) is located and comparing (S105) the measurement datum detected at a certain time (Rt) with a reference range (r*) relative to the measurement datum detected at the previous time (Rt-1) ; and transmitting (Sill) a message packet (M) comprising one or more measurement data (Rtl, Rt2, Rt3,...Rtn) detected at different time instants (tl, t2, t3,...tn) via a communication unit to the platform connected to the network, wherein the message packet is only transmitted when, among the component measurement data (Rtl, Rt2, Rt3,...Rtn) , the last measurement datum in terms of time is a measurement datum wherein the measurement datum (Rt) is outside the said reference interval (r*) and wherein the message packet (M) is transmitted to the platform (2) together with a subsequent accuracy value to be applied to the measurement data detected at times subsequent to that of transmission.

[0022] In general, lower amplitude ranges correspond to higher accuracy values.

[0023] It is noted that the amplitude of the value ranges (rl, r2, r3,...rm) of the detected physical quantity can be determined, both in the device and in the platform, based on the shared initial accuracy value (A) .

[0024] In this way, the residual battery capacity is optimized and the life of the device is increased. In fact, the transmission only takes place when the measured values are outside a certain range determined based on the defined accuracy value, so as to avoid ineffective battery consumption . In a second aspect of the invention, a method of receiving data by a service platform connected to a wireless network, in particular an Internet of Things network, is provided .

[0025] The method comprises : pre-determining an initial accuracy value between the device and the platform, wherein the initial accuracy value is previously communicated by the device to the platform or vice versa, or negotiated between the device and the platform, in particular according to the needs of the type of service ; establishing a set of reception times associated with the measurement of at least one physical quantity for di f ferent time instants by a wireless device connected to the network; receiving a first message packet at a first reception time , wherein the first message packet is composed of one or more measurement data associated with the measurement of the physical quantity and further comprises a subsequent accuracy value to be applied to subsequent reception times , waiting for the receipt of a new message packet for a first expected reception time , the first expected reception time being subsequent to the first reception time , wherein, i f said new message packet is not received for said first expected reception time , the method comprises :

[0026] - estimating the value of a measurement datum for said first expected reception time on the basis of the subsequent accuracy value and the measurement data received with the first message packet ; and

[0027] - continuing to estimate the value of a measurement datum at the reception times following the first reception time expected until the platform receives a second message packet at a second reception time ; receiving a second message packet composed of one or more measurement data detected at di f ferent time instants subsequent to those of the first message packet and including a subsequent accuracy value , wherein the time instants at which the measurement data of the second message packet were detected correspond to the expected reception times ; replacing the previously estimated values for the expected reception times with the values of the measurement data received with the second message packet associated with the same time instants ; and updating the subsequent accuracy value with that received with the second message packet and modi fying the criteria for estimating the values following receipt of the second message packet accordingly .

[0028] This reception method, when used in conj unction with the transmission method described above , is particularly advantageous when the platform must receive values at regular time intervals to ensure real-time operation with guaranteed system accuracy . In fact , although there are time intervals in which the platform does not receive data, it can estimate the data with guaranteed accuracy on the basis of the data previously received . In this way, the platform is able to determine possible data values with guaranteed accuracy even when the transmission device is in a phase of energy saving ( e . g . " sleep" ) .

[0029] Furthermore , the j oint use of the transmission and reception method described ensures that there is no loss of information ( it is therefore a so-called " lossless" system) , since the estimated values are subsequently replaced with those measured . This allows data to be used for an accurate description of the phenomena, for example for modelling purposes .

[0030] It is noted that in reference to the subsequent accuracy value to be applied to the subsequent reception times , for the first packet this value may conventionally be made to match the initial one , e . g . in order to simpli fy the implementation .

[0031] In a third aspect of the invention, there is provided a wireless device located within a wireless network, in particular an Internet of Things network . The device is configured to apply the method according to the first aspect . The device comprises : at least one sensor for measuring at least one physical quantity for di f ferent time instants and detecting a corresponding plurality of measurement data of said physical quantity; a controller connected to the sensor for managing the detected data, wherein the controller is configured to :

[0032] - divide a scale of the values of the physical quantity detected into disj oint and consecutive intervals , of homogeneous si ze and corresponding to an accuracy value ;

[0033] - determine for each time instant a range of values , within which each measurement datum is located and comparing the measurement datum detected at a certain time with a reference range relating to a measurement datum detected at the previous time instant ; classi fy the measurement datum as a standby measurement datum i f the measurement datum is within the reference range or as a transmission measurement datum i f the measurement datum is outside said reference range , and

[0034] - prepare a message packet comprising one or more measurement data detected at di f ferent time instants ; a battery, particularly a rechargeable battery, connected to the control unit to power the wireless device ; and a communication unit connected to the controller for transmitting the message packet to the platform, wherein the message packet is only transmitted when, among its component measurement data, the last measurement datum in terms of time is a transmission measurement datum and wherein the message packet is transmitted together with a subsequent accuracy value to be applied to the measurement data detected at times subsequent to that of transmission .

[0035] In a fourth aspect of the invention, there is provided an Internet of Things system comprising one or more wireless devices according to the third aspect of the invention, and at least one platform, wherein the one or more wireless devices are configured to exchange information with the platform over a wireless network .

[0036] In a fi fth aspect of the invention, there is provided a computer product , in particular a computer program, capable of performing the steps of the method according to the first aspect and / or second aspect . In a sixth aspect of the invention, there is provided a computer readable medium comprising a computer program for implementing the method according to the first aspect and / or second aspect .

[0037] These and other aspects of the present invention will become more apparent by reading the following description of some preferred embodiments disclosed below .

[0038] Fig . 1 shows a flow diagram of the transmission method according to one example .

[0039] Fig . 2 shows a flow diagram of the reception method according to one example .

[0040] Fig . 3 shows a schematic representation of an loT system according to one example .

[0041] Fig . 4 shows a schematic representation of an loT system according to one example .

[0042] Fig . 5 shows the standard power consumption of an loT device with " sleep" mode according to one example .

[0043] Fig . 6A-B show examples of a transmission operating method with regard to the device .

[0044] Fig . 7A-D show examples of a transmission operating method with regard to the platform . Fig . 8 shows the energy consumption of the loT device according to one example .

[0045] Fig . 9 shows a flow diagram of the transmission and reception method according to one example .

[0046] Fig . 10A-E show examples of diagrams for adj usting accuracy as a function of battery level according to one example .

[0047] Fig . 11A-B show examples of diagrams for adj usting accuracy as a function of battery level according to another example .

[0048] Fig . 12 shows a flow diagram of the transmission and reception method according to another example .

[0049] Fig . 13 shows a flow diagram of the transmission and reception method according to a further example .

[0050] Fig . 14A-B show examples of diagrams for accuracy change wherein the ranges of values constitute a series of predefined combinations .

[0051] Fig . 15A-D show examples of diagrams for the change in the accuracy based on a linear interpolation system .

[0052] Fig . 16A-B show the change in accuracy for times following the example of Figure 15 .

[0053] Fig . 17A-B show the change in accuracy by linear interpolation according to one example .

[0054] Figure 1 shows a flow diagram describing the method 100 for transmitting data . With reference to Figs . 3 and 4 , data are transmitted from a wireless device 1 to a service platform 2. Both the wireless device 1 and the platform 2 are connected to a wireless network 3. In the specific case described herein, the wireless device 1 is an loT device and the wireless network 3 is an loT network.

[0055] In step S101 of the method 100, an accuracy value A is defined between the device 1 and the platform 2. This is an initial value determined in advance that is previously communicated from the device 1 to the platform 2 or from the platform 2 to the device 1 or negotiated between the device and the platform. Similarly, the range of values of the measured quantity is predefined between device and platform, for example it is defined that the range goes from 0 to an rMAX value also based on the characteristics of the sensor (e.g. a sensor that is capable of measuring a temperature up to a tMAX value) . Once the initial accuracy value A has been established, a scale of values of the detected physical quantity is subdivided into disjoint and consecutive value ranges rl, r2, r3... rm in step S102. These ranges have a homogeneous size, that is, they are regular and uniform and depend on the initial accuracy value A. Higher accuracy values correspond to a smaller size of the ranges, for example, A = 1 / rm. It is noted that this step S102 may be skipped according to a generalization of the method 100.

[0056] For each time instant tl, t2, t3,...tn, the device 1 measures a physical quantity in a step S103. For example, the device 1 comprises a sensor 4 for measuring the ambient temperature or the value of a voltage. As a result, a set of measurement data Rtl is detected, for the first time instant and Rt2, Rt3,...Rtn for the subsequent times. In step S104 (performed for each time interval tl, t2, t3,...tn) , the range of values rl, r2, r3... rm within which the measurement datum Rtl (Rt2, Rt3,...Rtn) is located is determined and, in step S105, the measurement datum detected at a certain time instant (for example Rt with tl<t<tn) is compared with a reference range r* . This reference range r* is relative to the measurement datum detected at the previous time instant (for example Rt-1 ) .

[0057] If the measurement datum Rt is within the reference range r* , then this measurement datum Rt is classified or indicated as a standby measurement datum Ra (step S106) and stored (step S107) . If, on the other hand, the measurement datum Rt is outside the reference range r* , then this measurement datum Rt is classified or referred to as a transmission measurement datum Rtx (step S108) .

[0058] At this point, in step S109, the message packet M is prepared. The message packet M comprises one or more measurement data Rtl, Rt2, Rt3,...Rtn detected at different time instants tl, t2, t3,...tn. The message packet M is transmitted to the platform 2 via a communication unit 6 in step Sill.

[0059] It is noted that the message packet M is transmitted only if certain conditions are met. In particular, the message packet M is transmitted only if, among the component measurement data Rtl, Rt2, Rt3,...Rtn, the last measurement datum in terms of time is a transmission measurement datum Rtx. In addition, the message packet M is transmitted to the platform 2 together with a subsequent accuracy value Af to be applied to the measurement data detected at times subsequent to that of transmission, determined in step S110. At this step, the accuracy can be appropriately adjusted as will be described later .

[0060] In one example, the subsequent accuracy value Af matches the initial accuracy value A or the subsequent accuracy value Af is an updated accuracy value, different from the initial accuracy value A. In the first case, this means that the accuracy used initially can be used for subsequent measurements. In the second case, however, there was a need to change the accuracy, increasing or decreasing it depending on the situation, as will be described in detail later.

[0061] A device 1 used for the method 100 just described is schematically illustrated in Figure 3. The device 1 comprises at least one sensor 4 for measuring at least one physical quantity for different time instants tl, t2, t3,...tn and detecting a corresponding plurality of measurement data Rtl, Rt2, Rt3,...Rtn of said physical quantity. The device 1 further comprises a control unit 5 which is connected to the sensor 4 and to a memory 8 and which serves to manage the data detected by the sensor 4. The device 1 further comprises a battery 7, for example a rechargeable battery, connected to the controller

[0062] 5 for powering the wireless device 1 and a communication unit

[0063] 6 connected to the controller 5 for transmitting a message packet M to and receiving messages from the platform 2.

[0064] The controller 5 is configured to execute the process steps defined by the method 100 described above. Specifically, the control unit 6 is configured to determine for each time instant tl, t2, t3,...tn a range of values rl, r2, r3,...rn of accuracy A, within which each measurement datum Rtl, Rt2, Rt3,...Rtn is located and compare the measurement datum detected at a certain time with a reference range r* relative to a measurement datum detected at a previous time instant Rt-1. Furthermore, the control unit 5 is configured to classify the measurement datum as a standby measurement datum Ra if the measurement datum is within the reference range r* or as a transmission measurement datum Rtx if the measurement datum is outside said reference range r* . The control unit 5 is further configured to prepare a message packet M comprising one or more measurement data Rtl, Rt2, Rt3,...Rtn detected at different time instants tl, t2, t3,...tn and to adjust the subsequent accuracy value Af on the basis of the battery status and other parameters. As mentioned above, the message packet M is only transmitted when, among the component measurement data Rtl, Rt2, Rt3,...Rtn, the last measurement datum in terms of time is a transmission measurement datum Rtx.

[0065] According to one example, the device 1 further comprises an actuator 9 connected to the control unit 5. Additionally or alternatively, the device 1 comprises a charging unit 10, in particular powered by renewable energy, connected to the battery 7. Additionally or alternatively, the device 1 comprises a memory unit 8. This is shown schematically in Figure 4.

[0066] As regards its operation, the wireless device 1 may advantageously be an ToT device used to measure certain parameters (e.g. power consumption) via one or more dedicated sensors 4. Furthermore, the device 1 can be used to control certain actions via one or more dedicated actuators 9 (e.g. opening a valve or closing a switch) . The measurement of the parameters (and / or the control of certain actions) can be carried out continuously or regularly at well-defined time intervals, for example every 15 minutes. The measurement datum R(t) detected by the sensor 4 is sent to the control unit 5 while the control signal C(t) is sent by the control unit 5 to the corresponding actuator 9. The loT device 1 is connected to an loT platform via a wireless network 3 using a wireless connection as well, e.g. a radio connection. For this purpose, the loT device 1 is provided with a radio communication unit 6. The battery 7 is a rechargeable battery and can optionally be connected to a charging unit 10 based for example on solar photovoltaic panels, a wind turbine or any other power generation system.

[0067] Figures 3 and 4 also show an loT system 11 consisting of one or more loT devices 1 connected to the platform 2 via a wireless network 3, for example using a radio connection. It is noted that the transmission of messages takes place directly between the individual loT device 1 and the platform (or server) 2. In other words, there is no device, such as a gateway device, located between device 1 and platform 2. This ensures that energy consumption can be optimised directly from the individual integrated device 1 with respect to transmission to the platform 2.

[0068] The control unit 5 is able to control, and possibly power, the sensors 4 and to receive and sample the measurement data Rt for different time intervals tl, t2, t3,...tn. The measurement data Rt is processed by the controller 5 on the basis of the initial accuracy A and can be classified as standby measurement data Ra or as transmission measurement data Rtx . The transmission of a message packet M(t) containing the measurement data Rt is triggered by the presence of at least one transmission measurement datum Rtx . This is done via a transmission interface TX using the communication unit 6.

[0069] The control unit 5 is further able to control the value of the charge level B ( t ) of the battery 7 and to calculate di f ferent parameters on the basis of said value in order to measure the changes in charge level and the di scharge tendency of the battery . In other words , it is possible to estimate the useful li fe of the device 1 . Optionally, this estimate can be based on additional information such as the temperature of the battery 7 , for example through a dedicated sensor integrated into the battery 7 itsel f or through a reading of the ambient temperature .

[0070] Figure 2 shows a flow diagram describing the method 200 for receiving data . With reference to Figs . 3 and 4 , data are transmitted by a wireless device 1 and received by a service platform 2 . Both the wireless device 1 and the platform 2 are connected to a wireless network 3 . In the speci fic case described herein, the wireless device 1 is an loT device and the wireless network 3 is an loT network .

[0071] In a step S201a of the method 200 , an initial accuracy value may be determined between the device and the platform, wherein the initial accuracy value is previously communicated by the device to the platform or vice versa, or negotiated between the device and the platform

[0072] In step S201 of the method 200 a set of reception times tri , tr2 , tr3 , ...trn is established . These reception times tri , tr2 , tr3 , ...trn are associated with the measurement of a physical quantity by the wireless device 1 connected to the network 3 for a series of time instants tl , t2 , t3 , ...tn . In other words , a synchroni zation is determined between the measurement carried out , for example by a sensor 4 of the device 1 , at a time tl and the reception time tri at the platform 2 of the measured datum . At step S202 , the platform 2 receives a message packet M, for example a first message packet Ml , at a reception time tr, for example a first reception time tri . The message packet M received from the platform 2 comprises one or more measurement data Rtl , Rt2 , Rt3 , ...Rtn associated with the measurement of the physical quantity . For example , the first message packet Ml received at the reception time tri may comprise only the measurement datum Rtl detected by the sensor 4 of the device 1 at the time tl . The message packet further comprises , in general , an accuracy value A associated with the measurement data of the packets following the message packet M . It is noted that one way to communicate the initial accuracy value A to the platform is to associate this value with the first received message Ml together with the subsequent accuracy value ( this value for simplicity can be matched with A, this simpli fied case will be referred to below) , the initial accuracy value determined in advance can also be previously communicated from the device 1 to the platform 2 , from the platform to the device or negotiated between device and platform .

[0073] At step S203 , the platform 2 waits for the reception of a new message packet M, for example a second message packet M2 , for an expected reception time tpl . This expected reception time tpl is subsequent to the first reception time tri in which the platform 2 has received the first message packet Ml containing the measurement datum Rt and represents a time instant in which the platform 2 should receive a new message packet M relating to a measurement datum Rt+ 1 subsequent to that present in the first message packet Ml. As mentioned above, the platform 2 knows when the message packets M containing the measurement data Rtl, Rt2, Rt3,...Rtn must arrive as it is synchronized with the wireless device 1 and in particular with the detection times of the measurement data Rtl, Rt2, Rt3,...Rtn by a dedicated sensor 4.

[0074] At this point, the platform may or may not receive the new message packet M. If at the expected reception time tpl the message packet is not received, then a value of a measurement datum for this first expected reception time tpl is estimated on the basis of the known accuracy value A and on the basis of the measurement data associated with it received with the first message packet Ml. This estimation is made for all reception times following the first expected reception time tpl until the platform 2 receives a second message packet M2 at a second reception time tr2 (step S204) .

[0075] At step S205, the platform 2 receives a second message packet M2 composed of one or more measurement data Rtl, Rt2, Rt3,...Rtn detected at different time instants tl, t2, t3,...tn subsequent to those of the first message packet Ml and comprising a subsequent accuracy value Af . This subsequent accuracy value Af represents the accuracy value applied to the measurement data detected in times following that of the transmission of the first message packet Ml. It is noted that Af could match the initial value A or be different.

[0076] At step S206, the previously estimated values for the expected reception times tpl, tp2, tp3,...tpn are replaced by the values of the measurement data received with the second message packet M2 associated with the same time instants. Finally, the initial accuracy value A is updated with the following value Af received with the second message packet M2 and the estimation criteria of the values subsequent to the reception of the second message packet M2 are modi fied accordingly .

[0077] In one example , the value of the estimated measurement data for the expected reception times is calculated based on the accuracy value included in the last message packet received .

[0078] It is to be noted that the data transmission method 100 and the data reception method 200 described herein allow an optimisation of the energy consumption of the battery 7 present in the device 1 by allowing the accuracy to be dynamically changed within defined and controlled ranges according to the characteristics of the speci fic application method .

[0079] According to a standard operating principle that is known in the literature , in order to minimi ze battery power consumption, an loT local control system can establish a data connection with the platform and disconnect from the network by disabling radio communication to conserve battery power by entering a phase called " sleep" . In this case , the energy ef ficiency of the system, defined as the amount of time for operating the device given a certain battery capacity, is determined by the amount of energy required for transmission at each time interval At . Figure 5 shows an example according to the state of the art of the average energy consumption of an loT device that goes from the " sleep" phase , with low consumption, to the data transmission and processing phase , with high consumption, periodically . However, this approach is not very ef ficient with regard to the energy savings of the battery since an energy consumption is determined for each time interval At in which data is transferred, regardless of the trend of the phenomenon whose measurements are transmitted and in particular the accuracy A.

[0080] The methods described here are instead more efficient with regard to the energy saving of the battery 7 associated with the wireless device 1. In fact, the message packets M(t) are transmitted only when the measurement data Rt reflect certain conditions with reference to the accuracy of the detected measurement, as shown in Figure 8. In addition, the accuracy can be dynamically changed to optimize the remaining battery charge .

[0081] Depending on whether the measurement datum is inside or outside a certain reference range r* , the measurement datum Rt is classified as a standby measurement datum Ra and therefore is not transmitted, or as a transmission measurement datum Rtx and therefore is transmitted. In one example, each measurement datum classified as a standby measurement datum Ra (i.e. inside the reference range r*) is saved inside the memory unit 8 of the wireless device 1 until the time instant in which a measurement datum is classified as a transmission measurement datum Rtx (i.e. outside the reference interval r*) and, starting from said time instant, each standby measurement datum Ra saved in the memory unit 8 is inserted in the message packet M to be transmitted together with the transmission measurement datum Rtx.

[0082] In one example, the accuracy value A has a minimum value determined by the wireless device 1, wherein in particular said minimum value corresponds to a maximum size of the corresponding intervals rl, r2,...rm. For example, this value can be programmed into the firmware of the device 1. Alternatively, the accuracy value A has a minimum value established by a reception message (acknowledgement message) , in particular an acknowledgement signal, transmitted by the platform 2 and received by the wireless device 1. In this way, the platform 2 can determine the minimum accuracy that the wireless device 1 must use up to a new message from the platform 2.

[0083] Figures 6A-B show an example of the application of methods 100, 200 described here. The device 1 measures a physical quantity for the time intervals tl-t7. The graph in Figure 6A shows the time intervals on the axis of the abscissas and the values of the measurement data Rt on the axis of the ordinates. In particular, the ordinate axis is subdivided into disjoint and consecutive value ranges rl, r2, r3,...rm that correspond to the initial accuracy value A. Assuming that the device 1 is measuring a temperature and that the initial accuracy has been determined such that the data range is 2 °C, the value ranges rl, r2, r3,...rm will then vary by 2°C. For example, the value of rl=[rlmin, rlmax] may be a range between 28°C and 30°C, the value of r2=[r2min, r2max] may be a range between 30°C and 32°C, the value of r3=[r3min, r3max] may be a range between 32 °C and 34°C, and so on. At time tl, the control unit 5 of the wireless device 1 determines the range of values in which the first measurement datum is located (e.g. Rtl= 31.1°C) . In the case of the figure, this range is r2.

[0084] In the example of Figure 6A, at time tl the transmission of the message packet M(tl) containing the measurement datum Rtl is triggered. The symbol of the black triangle at time tl refers to an event of data transmission from the device 1 to the platform 2. The platform 2 receives the packet M(tl) and possibly sends a reception message based for example on the particular radio protocol used by the radio connection.

[0085] At times t2 and t3, e.g. 15 minutes and 30 minutes respectively from the first measurement at time tl (At= 15 minutes) , two new temperature measurements (Rt2 and Rt3) are made. For example, Rt2= 31.4°C and Rt3=29.8°C. Since the control unit 5 determines that both Rt2 and Rt3 are within the reference range r* , i.e. are within the same range as Rtl, the values of Rt2 and Rt3 are both classified as standby values Ra and saved in the memory unit 8. In this case, no transmission to the platform 2 is triggered either at time t2 or at time t3. However, the platform 2 performs an estimation of the measurement data for these time instants t2 and t3. The estimated values are temporary in the sense that these will be replaced by the actually measured values later, when a new data transmission will take place from device 1 to platform 2. The black square symbol at times t2 and t3 refers to a data estimation event by platform 2. The values used as estimated values are represented by the average value of the range of values in which there is the last datum transmitted, i.e. Rtl with M(tl) . In particular, the estimated values will be rlmax+r* / 2, for example 30°C + (32°C - 30°C) / 2 = 31°C with an error respectively equal to -0.4°C and +1.2°C with respect to the actual values respectively 31.4°C and Rt3=29.8°C. In other words, since the values actually measured are within the initially determined accuracy range, the platform 2 assumes that they do not deviate much from the last value received and the device 1 can avoid transmitting the real values at times t2 and t3, thus reducing the power consumption of the battery 7. Figure 6A shows in the graph the trend of the values actually measured with a solid line while showing the trend of the estimated values with a dotted line.

[0086] At time t4 a value of Rt4 = 34.9°C is measured. In this case, the control unit 5 determines that this value is outside the reference range r* relative to the previous time instant (t3) . For this reason, Rt4 is classified as a transmission value Rtx and a transmission to the platform 2 is then triggered. A message packet M(t4) is formed which contains not only the value Rt4 but also the values Rt2 and Rt3 previously saved in the memory unit 8. As shown in the figure, the message packet M(t4) will be longer than the previous one M(tl) as it consists of a set of values at times t2, t3 and t4. When the M(t4) packet is received from the platform 2, the values that had been previously estimated for the times t2 and t3 are replaced with the values actually measured and contained in the M(t4) message packet, this ensures that the platform acquires the actual measurement values.

[0087] Considering the subsequent time instants, t5, t6 and t7 , the example of Figure 6A shows how at time t5 and time t6 the transmission of the message packets M(t5) and M(t6) takes place since the measured values Rt5 and Rt6 are outside the corresponding reference range r* of the previous datum (respectively at time t4 for Rt5 and time t5 for Rt6) and are therefore classified as transmission values Rtx. For example, Rt5= 36.4°C (which is outside the reference range r*= [34°C, 36°C] time t4) and Rt6 = 32.9°C which is outside the reference range r*= [36°C, 38°C] at time t5) . On the other hand, since at time t7 a value within the same reference range r*= [32°C, 34°C] of Rt6 is measured, no transmission will occur and the value of Rt7 (e.g. Rt7 = 33.1°C) is classified as a standby value Ra and saved in the memory unit 8 in standby for it to be transmitted later when a new transmission is triggered. Figure 6B shows the same phenomenon as in the example of Figure

[0088] 6A, in which, however, the initial accuracy is different, specifically equal to half that of Figure 6A. In particular, the axis of the ordinates is divided into ranges of disjoint and consecutive values rl, r2, r3,...rm that correspond to the value of an initial accuracy A such that the reference range is 2r*, i.e. twice that of Figure 6A. Consider an initial accuracy value A such that the ranges of values rl, r2, r3,...rm vary by 4°C. For example, the value of rl can be rl=[26°C, 30°C] , the value of r2 can be r2=[30°C, 34°C] , the value of r3 can be r3=[34°C, 38°C] , and so on. As in Figure 6A, at time tl, the control unit 5 of the wireless device 1 determines the range of values in which the first measurement datum is located (e.g. Rtl= 31.1°C) . In the case of the figure, this range is r2 and can be considered as a reference range 2r* . In this case, 30°C < 2r* < 34°C.

[0089] Given the lower accuracy, the data may or may not be transmitted at different times. In this case, between times tl and t4 the transmission trend will be the same as in Figure 6A. The only difference concerns the estimation of the values at times t2 and t3 which results in higher values due to lower accuracy. In particular, the estimated values will be rlmax+2r* / 2, i.e. 30°C + (34°C - 30°C) / 2 = 32°C. Unlike the case of Figure 6A, the value at time t5 is classified as a standby value Ra as within the same range as the value at the previous time Rt4, i.e. 2r*=[34°C, 38°C] . Therefore, at time t5 no transmission will occur and the platform will be able to estimate a value for time t5 considering the lower accuracy and previous reference range, for example r2max+2r* / 2 34 °C + (38°C - 34°C) / 2 = 36°C. The value actually measured at time t5 and temporarily saved in the memory unit 8 is transmitted from the device 1 to the platform 2 at time t 6 with the message packet M ( t 6 ) and will take the place of the value estimated by the platform 2 upon receipt of message packet M ( t 6 ) .

[0090] Figures 7A-D show a detail of the data estimated by the platform 2 between times tl and t5 with respect to the example of Figure 6B . It is noted that in this time frame there are only two transmission events at times tl and t4 and that the estimated data at times t2 , t3 and t5 are later replaced by the data actually measured with the next transmission .

[0091] The data transmission and data reception methods described here show various advantages in that they provide a short-term estimate with a well-defined and controlled accuracy for ( temporarily) untransmitted data and provide all the data actually measured in the long term . Since for each time instant the accuracy is known for both the wireless device 1 and the platform 2 , assuming that this accuracy is appropriately adj usted within values defined by the type of application ( for example liquid flow control ) , the real-time estimated data can be used by the platform 2 to control , within known limits of accuracy, the trend of a phenomenon and / or regular process actuators while the actual measured data, available at a later time , can be used to adj ust an accurate model and for other uses where more precise data is needed .

[0092] In one example , the method 100 further comprises :

[0093] - measuring the charge level of a battery 7 of the wireless device 1 , and - adjusting the subsequent accuracy value Af as a function of the measured charge level value by correspondingly changing the size of the intervals rl, r2, r3... rm.

[0094] In particular, the size of the intervals is decreased when the subsequent accuracy value Af is increased, or increased when the subsequent accuracy value Af is decreased.

[0095] Specifically, the method comprises calculating a rate of change of the charge level of the battery 7 in a certain time interval, in particular between a time instant of transmission of the message M(t) and the time instant of transmission of the previous message M(t-l) and / or between a time instant of measurement of the physical quantity (t) and the previous time instant (t-1) and adjusting, in particular increasing or decreasing, the subsequent accuracy value Af as a function of the value of said rate of change of the charge level of the battery 7.

[0096] In other words, the accuracy level may be dynamically determined by the control unit 5 on the basis of the state and trend of the measured residual charge B(t) . In this way, the accuracy of the measurement data estimated by the platform 2 can be dynamically adjusted by the wireless device 1. For example, the accuracy may be decreased when the battery charge is low and a small number of transmissions need to be sent, or it may be increased when the battery charge is high and allows a larger number of transmissions. In this way, the useful life of the device 1 can be increased within certain data accuracy limits, which can in turn be predefined on the basis of the application or (optionally) can be adjusted by the platform 2 by sending the maximum and / or minimum usable accuracy value to the device 1 .

[0097] By applying the methods described above , the power consumption of the wireless device 1 can then be reduced . Figure 8 shows , for example , the trend of energy consumption as a function of time , for example between time instants tl and t4 , with reference to the graphs of Figure 6A and 6B in which the transmission occurs only at time instants tl and t4 . Comparing the graph of Figure 8 with that of Figure 5 , it is immediately noticeable how the average energy consumption in the range tl- t4 is decidedly lower i f the methods described here are applied ( Figure 8 ) . In the graph of Figure 8 it is noted that at the data processing step there is below average energy consumption . This represents all data processing processes except transmission, e . g . insertion of the measured data into the memory unit 8 . It is noted that data processing times are also generally shorter than those relating to data transmission ( also depending on the radio protocols used) .

[0098] As shown in Figure 4 , the loT device 1 may comprise more than one sensor 4 . In this situation, the control unit 5 is able to obtain multiple measurements of di f ferent parameters at the same time t . In other words , the device 1 is able to obtain a set n of measurements that can be represented by a vector in an n-dimensional space . For example , a two-dimensional vector may include both a power consumption reading and a temperature reading at time t . Accordingly, the message packet M ( t ) is represented by a matrix including a number of subsequent measurement vectors . The methods described above can be applied to a multidimensional case in which the basic principle can be applied to each dimension n . For example , the methods can be applied to energy consumption and temperature values in which the control unit 5 dynamically adj usts the accuracy value for each dimension within the limits defined for each dimension .

[0099] Figure 9 shows a flow diagram for a process of intermittent transmission by the loT device 1 and reception by the loT platform 2 . It is noted that the accuracy is adj usted on the basis of some parameters such as , for example , whether the residual charge runtime of the battery 7 is above or below a certain threshold or whether a measurement limit value has been exceeded .

[0100] According to one example , the transmission method 100 comprises determining a standby threshold value Na, wherein i f the number of consecutive measurement data Rtl , Rt2 , Rt3 , ...Rtn classi fied as standby measurement data Ra exceeds said threshold value Na, corresponding to the time interval between tl and tn, then the immediately following measurement datum is classi fied as a transmission measurement datum Rtx . In this way it is possible to limit the time within which the platform will definitely receive a measurement message M, for example for applications that need to periodically check ( e . g . every 24 hours ) the extent of the estimation errors .

[0101] Analogously to the previous example , limiting the maximum number of missed transmissions can be advantageously used to realise control systems with actuators .

[0102] As already mentioned above , the loT device 1 may include one or more actuators 9 . Each actuator 9 is controlled by the control unit 5 at time t by a command C ( t ) based on the data processed in the device 1 and / or on command input signals from the platform 2 received in acknowledgement messages at the transmission by the device 1 of messages M . In the latter case , it is possible to introduce a maximum latency command, i . e . it is possible to introduce an additional parameter in the control system based on a maximum interval T - corresponding to a number of consecutive time intervals At - without any transmission taking place . In this case , the message packet M ( T ) includes all the measurements during these time intervals and a transmission is triggered by the control unit 5 regardless of the controls based on the accuracy value .

[0103] In this way, the platform 2 can receive the real data within a certain time T and provide the device 1 with the commands for the actuators 9 with a maximum controlled latency T . Such a scenario guarantees an advantageous solution when the loT device 1 statistically transmits data within a certain time span but is required not to exceed a certain time to receive control inputs from the platform 2 that are necessary for adequate operation of the actuators 9 .

[0104] Speci fically, according to one example , the transmission method 100 comprises introducing a maximum controlled latency value T corresponding to a number of consecutive time intervals without any transmission taking place and classi fying the measurement datum Rt as a transmission measurement datum Rtx once the maximum controlled latency time value T has been reached and sending to the platform 2 a subsequent accuracy value Af updated together with the message packet M .

[0105] Figures 10A-E show an example of adj usting the accuracy as a function of the charge level of the battery 7 of the device 1 . Figure 10A shows in particular the change in the charge level of the battery 7 with respect to time , for example over the course of a day . Assuming that the battery 7 is connected to a solar charging unit 10 , the charge level decreases at night and then increases during the day . Speci fically, the charge level can be divided into three bands , namely a band A with a high charge level , a band B with an intermediate charge level and a band C with a low charge level . The accuracy of the system is adj usted by the control unit 5 in the transition from one band to another ( Figure 10B ) . For example , when the charge level of the battery 7 is in the band A, the accuracy has a high value and the transmission of the measured data can be carried out according to the graph in Figure 10c . Moving to a charge level in band B, the accuracy decreases and the transmission of the measured data can be carried out according to the graph in Figure l Od . For example , halving the accuracy means that in the graph of Figure l Od the ranges of the values rl , r2 , r3 , ...rm are spaced twice as far apart as the ranges of Figure 10c . Turning then to the charge level in band C, the accuracy decreases further and the transmission of the measured data can take place according to the graph in Figure 10E . For example , halving the accuracy means that in the graph of Figure 10E the ranges of the values rl , r2 , r3 , ...rm are spaced twice as far apart as the ranges of Figure l Od ( four times as far apart as the ranges of Figure 10C ) . The graphs in Figures 10A- E show how a compromise is determined between the need to save energy consumption by avoiding data transmissions and the need to obtain measurements with good accuracy . It should also be noted that there is no loss of information since the actual values of the previously estimated data are received from the platform in correspondence with the transmissions . Figures 11A and 11B show how the accuracy can be adjusted when the battery level (dotted line in Figure 11B) has reached a certain level. Specifically, when the control unit 5 of the device 1 determines that the level of the battery 7 is above a certain threshold value TB and the measured value R(T) is deemed to be stable within a certain accuracy range (e.g. when two or more consecutive measured values are within this accuracy range during a specific time interval e.g. night) , a transmission event may take place for the sole purpose of increasing the accuracy (symbol with two triangles superimposed on the time tc in Figure 11A) and providing the platform 2 with the new accuracy value. With reference to the figure, after the time tc the accuracy has increased by a factor of 2 without the need for there to be a subsequent transmission by the device 1. In this way, the device 1 improves the accuracy while preserving the battery charge. This aspect is illustrated in the flow diagram of Figure 12 and Figure 13. These figures show a flow diagram similar to that of Figure 9 in which however a test is included relating to the evaluation of the battery charge level above the threshold TB for a certain period of time at different stages of the process of detecting the measured data values and preparing the message packet M(t) .

[0106] The method so far described by exemplifying the disjoint and consecutive ranges as being of homogeneous size for each accuracy value, can be generalized.

[0107] The accuracy can be dynamically varied in different ways as explained below.

[0108] According to one example, the dimensions of each of the disjoint and consecutive intervals rl, r2, r3... rm are variable constituting a series of k predefined combinations Cl, C2...Ck to each of which corresponds a subsequent accuracy value rCl, rC2... rCk that is associated with the transmission of the message M. This is shown in Figures 14A-B. In particular, the intervals are variable between a minimum value and a maximum value. For example, the range is wider (e.g. rl in Figure 14) in regions where the occurrence of R(t) values is more unlikely while the range is narrower (e.g. r2 in Figure 14) in regions where the occurrence of R(t) values is more likely. The probability of occurrence of R(t) can be defined in advance or dynamically through an analysis of the probability distribution function. In such a situation, the accuracy value exchanged by message between the wireless device 1 and the platform 2 may be replaced by a predefined combination C representing a specific configuration of variable ranges within a predefined set of values that is known to both the device 1 and the platform 2. As shown in Figure 14, C may take the value of Cl containing ten variable ranges between rl and r2 or C may take the value C2 containing eight variable ranges between rl and r2. For example, assuming C=C1 at tl, the device 1 may set C=C2 at time t2 so that the interval configuration is changed by changing from ten to eight intervals with a different distribution.

[0109] The dynamic change of the accuracy and the way in which the measured data values are estimated can take place in different ways. One of these uses a tracking method with estimation based on a linear system.

[0110] In one example, the midpoint of the reference interval r* is positioned at time t on a line passing through the values Rt- 1 and Rt, wherein the value Rt and subsequent values are classified as standby Ra if they remain within the reference interval r* whose midpoint is positioned on said line at the points corresponding to the times tl, t2,...tn subsequent to t and as transmission Rtx otherwise. In the case of transmission at the generic time tk, the estimation line is repositioned as passing between the point corresponding to the actual value Rtk-1 corresponding to the immediately preceding time tk-1 and the value Rtk corresponding to the time tk. This is shown in Figs. 15A-D. In this case, the position of the interval for the subsequent transmission is based on an adaptive model using a linear interpolation thereby allowing the values of the intervals to continuously change in the range of R(t) . With reference to the figures, at time t3 no transmission occurs if the actual measured value is within the range ±r* / 2 from the linear interpolation based on the two measured values at times tl and t2. In the example of Figures 15, the value measured at time t3 is not transmitted while that measured at time t4 and time t5 is as outside the range ±r* / 2 from the linear interpolation based on the last two previously measured values.

[0111] Figures 16A-B show an approach similar to that shown in Figures 15A-D, wherein the accuracy varies, in particular decreases, at time t6 and is applied to subsequent measurements. In this example, three transmissions take place on seven measurements made by the device 1, namely M(tl) , M(t4) and M(t6) respectively at times tl, t4 and t6.

[0112] Figures 17A-B show that in the case of a linear interpolation, the envelope of the accuracy range moves along the measurement at discrete times potentially ensuring better efficiency (in terms of average number of transmission events) than in the case of uniform distribution of ranges (e.g. Figure 6) depending on the intrinsic characteristics of the data measured by the sensor .

[0113] The system 11 described herein is an integral part of the data transmission and reception method for achieving a desired balance between the battery li fe of the device 1 and the dynamic performance of the system itsel f . It is noted that the real values measured by the device 1 will sooner or later always be transmitted to the platform 2 while the estimated values will be produced by the platform 2 in real time in a way that can be immediately used in applications that require this data and subsequently replaced by real data, when conditions permit .

[0114] A person skilled in the art may perform numerous further modi fications and variations to the methods , to the device and to the system described above , in order to satis fy further and contingent requirements , all said modi fications and variations being however included within the scope of protection of the present invention as defined by the appended claims .

Claims

CLAIMS1. Method of data transmission (100) by a wireless device (1) connected to a wireless network (3) , in particular an Internet of Things network, connecting the device (1) to one or more service platforms (2) , the method (100) comprising : pre-determining (S101) an initial accuracy value (A) between the device (1) and the platform (2) for at least one physical quantity measured by the wireless device (1) , wherein the initial accuracy value (A) is previously communicated by the device (1) to the platform (2) or vice versa, or negotiated between device and platform; measuring (S103) the physical quantity using the wireless device (1) for different time instants (tl, t2, t3,...tn) and detecting a corresponding plurality of measurement data (Rtl, Rt2, Rt3,...Rtn) of said physical quantity by means of at least one sensor (4) ; for each time instant (tl, t2, t3,...tn) determining (S104) a range of values (rl, r2, r3,...rm) within which each measurement datum (Rtl, Rt2, Rt3,...Rtn) is located and comparing (S105) the measurement datum detected at a certain time (Rt) with a reference range (r*) relative to the measurement datum detected at a previous time (Rt-1) ; and transmitting (Sill) a message packet (M) comprising one or more measurement data (Rtl, Rt2, Rt3,...Rtn) detected at different time points (tl, t2, t3,...tn) via a communication unit (6) to the platform (2) connected to the network (3) , wherein the message packet (M) is only transmitted when, among the component measurement data (Rtl, Rt2, Rt3,...Rtn) , the last measurement datum in terms of time is ameasurement datumwherein the measurement datum (Rt) is outside the said reference interval (r*)and wherein the message packet (M) is transmitted to the platform (2) together with a subsequent accuracy value (Af) to be applied to the measurement data detected at times subsequent to that of transmission.

2. Data transmission method (100) according to Claim 1, wherein the subsequent accuracy value (Af) coincides with the initial accuracy value (A) or the subsequent accuracy value (Af) is an updated accuracy value different from the initial accuracy value (A) .

3. Data transmission method (100) according to any of the preceding claims, wherein each measurement datum within the reference range (r*) is classified as a standby measurement datum (Ra) and each measurement datum outside said reference range (r*) is classified as a transmission measurement datum (Rtx)and wherein each standby measurement datum (Ra) is saved within a memory unit (8) of the wireless device (1) until the time point at which a measurement datum is classified as a transmission measurement datum (Rtx) and, starting from said time point, each standby measurement datum (Ra) saved in the memory unit (8) is inserted in the message packet (M) to be transmitted together with the transmission measurement datum (Rtx) .

4. Data transmission method (100) according to any of the preceding claims, wherein the initial accuracy value (A) has a minimum value determined by the wireless device (1) , wherein in particular said minimum value corresponds to a maximum size of the corresponding intervals (rl, r2,...rm) , oris established by a reception message, in particular an acknowledgement signal, transmitted by the platform (2) and received by the wireless device (1) .

5. Method of data transmission (100) according to any of the preceding claims, further comprising: measuring the charge level of a battery (7) of the wireless device (1) ; and adjusting the subsequent accuracy value (Af) as a function of the measured charge level value by correspondingly changing the size of the intervals (rl, r2, r3... rm) , wherein in particular, the size of the intervals is decreased when the subsequent accuracy value (Af) is increased, or increased when the subsequent accuracy value (Af) is decreased.

6. Data transmission method (100) according to Claim 5, further comprising calculating a rate of change of the charge level of the battery (7) in a certain time interval, in particular between a time point of transmission of the message M(t) and the time point of transmission of the previous message M(t-l) and / or between a time point of measurement of the physical quantity (t) and the previous time point (t-1) , and adjusting, in particular increasing or decreasing, the subsequent accuracy value (Af) as a function of the value of said rate of change of the charge level of the battery ( 7 ) .

7. Method of data transmission (100) according to any of the preceding claims, comprisingdetermining a standby threshold value (Na) , wherein if the number of consecutive measurement data (Rtl, Rt2, Rt3,...Rtn) classified as standby measurement data (Ra) exceeds said threshold value (Na) , corresponding to the time interval between tl and tn, then the immediately following measurement datum is classified as a transmission measurement datum (Rtx) .

8. Method of data transmission (100) according to any of the preceding claims, comprising introducing a maximum controlled latency value (T) corresponding to a number of consecutive time intervals without any transmission taking place; and classifying (S108) the measurement datum (Rt) as a transmission measurement datum (Rtx) once the maximum controlled latency time value (T) is reached and sending to the platform (2) an updated subsequent accuracy value (Af) together with the message packet (M) .

9. Method of data transmission (100) according to any of the preceding claims, further comprising dividing (S102) a scale of the values of the physical quantity detected into intervals of disjoint and consecutive values (rl, r2, r3... rm) of homogeneous size and dependent on the initial accuracy value (A) , wherein in particular the dimensions of each of the disjoint and consecutive intervals (rl, r2, r3... rm) are variable constituting a series of k predefined combinations (Cl, C2...Ck) to each of which corresponds a subsequent accuracy value (AC1, AC2... ACk) that is associated with the transmission of the message M.

10. Method of data transmission (100) according to any of the preceding claims, wherein the midpoint of the reference range r* is positioned at time t on a line passing through the values Rt-1 and Rt, wherein the value Rt and subsequent values are classified as standby data (Ra) if they remain within the reference range r* whose midpoint is positioned on said line at the points corresponding to the times (tl, t2,...tn) following t and as transmission (Rtx) otherwise.

11. Method of receiving data (200) by a service platform (2) connected to a wireless network (3) , in particular an Internet of Things network, the method (200) comprising : pre-determining an initial accuracy value between the device (1) and the platform (2) , wherein the initial accuracy value is previously communicated from the device (1) to the platform (2) or vice versa, or negotiated between the device (1) and the platform (2) ; establishing (S201) a set of reception times (tri, tr2, tr3,...trn) associated with the measurement of at least one physical quantity for different time instants (tl, t2, t3,...tn) by a wireless device (1) connected to the network (3) ; receiving (S202) a first message packet (Ml) at a first reception time (tri) , wherein the first message packet (Ml) is composed of one or more measurement data (Rtl, Rt2, Rt3,...Rtn) associated with the measurement of the physical quantity and further comprises a subsequent accuracy value (Af) to be applied to subsequent reception times; waiting (S203) for the receipt of a new message packet for a first expected reception time (tpl) , the first expectedreception time (tpl) being subsequent to the first reception time (tri) , wherein, if said new message packet is not received for said first expected reception time (tpl) , the method comprises: estimating (S204) the value of a measurement datum for said first expected reception time (tpl) on the basis of the subsequent accuracy value (AfMl) and the measurement data received with the first message packet (Ml ) ; and continuing to estimate the value of a measurement datum at the subsequent reception times (tp2, tp3,... tpn) at the first expected reception time (tpl) until the platform (2) receives a second message packet (M2) at a second reception time (tr2) ; receiving (S205) a second message packet (M2) composed of one or more measurement data (Rtl, Rt2, Rt3,...Rtn) detected at different time points (tl, t2, t3,...tn) following those of the first message packet (Ml) and including a subsequent accuracy value (Af), wherein the time points (tl, t2, t3,...tn) at which the measurement data of the second message packet (M2) were detected correspond to the expected reception times (tpl, tp2, tp3,...tpn) ; replacing (S206) the previously estimated values for the expected reception times (tpl, tp2, tp3,...tpn) with the values of the measurement data received with the second message packet (M2) associated with the same time instants; and updating (S207) the subsequent accuracy value (AfMl) with that (AfM2) received with the second message packet (M2)and correspondingly modifying the estimation criteria of the values following receipt of the second message packet (M2) .

12. Data reception method (200) according to Claim 11, wherein the value of the estimated measurement data for the expected reception times is calculated based on the accuracy value included in the last message packet received.

13. Wireless device (1) located within a wireless network (3) , in particular an Internet of Things network, wherein the device (1) comprises: at least one sensor (4) for measuring at least one physical quantity for different time instants (tl, t2, t3,...tn) and detecting a corresponding plurality of measurement data (Rtl, Rt2, Rt3,... Rtn) of said physical quantity; a controller (5) connected to the sensor (4) to manage the detected data, wherein the controller (4) is configured to :- divide a scale of the values of the physical quantity detected into disjoint and consecutive intervals, of homogeneous size and corresponding to an accuracy value ;- determine for each time instant (tl, t2, t3,...tn) a range of values (rl, r2, r3,...rn) of accuracy A, within which each measurement datum (Rtl, Rt2, Rt3,...Rtn) is located and compare the measurement datum detected at a certain time (Rt) with a reference range (r*) relating to a measurement datum detected at the previous time (Rt-1) ;classify the measurement datum (Rt) as a standby measurement datum (Ra) if the measurement datum (Rt) is within the reference range (r*) or as a transmission measurement datum (Rtx) if the measurement datum (Rt) is outside said reference range (r*) , and- preparing a message packet (M) comprising one or more measurement data (Rtl, Rt2, Rt3,...Rtn) detected at different time points (tl, t2, t3,...tn) ; a battery (7) , in particular a rechargeable battery, connected to the control unit (5) for powering the wireless device ( 1 ) ; and a communication unit (6) connected to the control unit (5) for transmitting the message packet (M) to the platform (2) , wherein the message packet (M) is only transmitted when, among the component measurement data (Rtl, Rt2, Rt3,...Rtn) , the last measurement datum in terms of time is a transmission measurement datum (Rtx) and wherein the message packet (M) is transmitted together with a subsequent accuracy value (Af) to be applied to the measurement data detected at times subsequent to that of transmission.

14. Device (1) according to Claim 13, further comprising : a. at least one actuator (9) connected to the control unit ( 5 ) , and / or b. a charging unit (10) , in particular powered by renewable energy, connected to the battery (7) , and / or c. a memory unit (8) .

15. Internet of Things system (11) , comprising: one or more wireless devices (1) according to any ofClaims 13 to 14, and at least one platform (2) , wherein the one or more wireless devices (1) are configured to exchange information with the platform (2) through a wireless network (3) .

16. Computer product, in particular computer program, capable of performing the steps of the data transmission method (100) according to any of Claims 1 to 10 and / or of the data reception method (200) according to any of Claims 11 to 12.

17. Computer-readable medium comprising a computer program for implementing the data transmission method (100) according to any of Claims 1 to 10 and / or the data reception method (200) according to any of Claims 11 to 12.

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