WO2017046143A1

WO2017046143A1 - Method of transmitting data from a mobile transmitter device to a host unit, and mobile transmitter device

Info

Publication number: WO2017046143A1
Application number: PCT/EP2016/071662
Authority: WO
Inventors: Przemyslaw PAWELCZAK; Ivar IN 'T VEEN; Qingzhi Liu
Original assignee: Technische Universiteit Delft
Priority date: 2015-09-14
Filing date: 2016-09-14
Publication date: 2017-03-23
Also published as: NL2015432B1

Abstract

Mobile transmitter device (1) having an active radio transmitter (2), a backscatter radio transmitter (3), and a control unit (5). The control unit (5) is e.g. arranged to execute a method of transmitting data from a mobile transmitter device (1) to a host unit (9). For that, it is arranged to select operation of the active radio transmitter (2), the backscatter radio transmitter (3) or both the active radio transmitter (2) and the backscatter radio transmitter (3), in a transmission mode for transmitting data to a host unit (9). Selecting the backscatter radio transmitter (3) as an operative part of the mobile transmitter device (1) is executed if a backscatter condition is fulfilled. The backscatter condition is e.g. that a channel quality indicator of a communication channel between the backscatter radio transmitter (3) and the host unit (9) is higher than a predetermined quality threshold value.

Description

Method of transmitting data from a mobile transmitter device to a host unit, and mobile transmitter device

Field of the invention

The present invention relates to a method of transmitting data from a mobile transmitter device to a host unit, the method comprising using a combination of an active radio transmitter and a backscatter radio transmitter in the mobile transmitter device. In a further aspect, the present invention relates to a mobile transmitter device comprising an active radio transmitter, a backscatter radio transmitter, and a control unit connected to the active radio transmitter and the backscatter radio transmitter.

Prior art

American patent publication US-B-7,215,976 discloses a device having both a RFID backscatter part and a Bluetooth radio part. The device can operate in a backscatter (RFID) mode or in a regular (active) mode. The RFID receiver part is e.g. used to receive a wake-up signal from another radio unit within a certain range (e.g. an Access Point), and the device is arranged to activate the Bluetooth radio part only after receiving such a wake-up signal, thus more efficiently using energy resources.

American patent publication US2002/0126013 discloses a device having an RFID radio interface part and a Bluetooth radio interface part. The device is arranged to localize other devices in its vicinity, e.g. having an RFID tag or a device having a wireless Bluetooth communication capability.

Summary of the invention

The present invention seeks to provide an improved mobile transmission device allowing efficient and reliable data communication to a host unit.

According to the present invention, a method according to the preamble defined above is provided, wherein the method comprises selecting the backscatter radio transmitter as an operative part of the mobile transmitter device if a backscatter condition is fulfilled, the backscatter condition comprising that a channel quality indicator of a communication channel between the backscatter radio transmitter and the host unit is higher than a predetermined quality threshold value. This will ensure that there is a high enough chance of successful data transmission using the backscatter radio transmitter to the host unit.

In an embodiment, the method further comprises selecting the active radio transmitter as operative if the backscatter condition is not fulfilled. This would properly define when switching from backscatter radio transmitter to active radio transmitter is performed. In a further alternative, it is made possible that both the active and backscatter radio transmitters are active at the same time.

The backscatter condition may comprise that the number of other nearby operating backscatter radio transmitters is lower than a predetermined number threshold value. This will result in a lower risk of interfering transmissions from other mobile transmitter devices nearby.

In a further embodiment, the channel quality indicator is calculated or estimated based on previous data transmissions between the backscatter radio transmitter and the host unit. This allows to cater for various circumstances, such as range, received power for backscatter, and other interfering factors.

The backscatter radio transmitter comprises an energy harvesting part connected to an energy storage in a further group of embodiments. The method then further comprises monitoring the amount of energy stored in the energy storage, and using the monitored amount of energy as a further or additional backscatter condition for selecting operation of the active radio transmitter, the backscatter radio transmitter or both the active radio transmitter and the backscatter radio transmitter. This would exploit the possible benefits of using the backscatter radio transmitter to a high extent.

In an even further embodiment, selecting the backscatter radio transmitter and/or active radio transmitter is based upon a machine learning algorithm, which would allow to optimize performance over time.

The active radio transmitter is an IEEE 802.15.x transmitter in a specific embodiment, e.g. using a Bluetooth or even Bluetooth low energy (BLE)

implementations of the active radio transmitter. Furthermore, the backscatter radio transmitter may be implemented as an RFID transmitter, e.g. a Computational RFID transmitter (having its own processing unit).

In an even further embodiment, the method further comprises receiving sensor data and converting the sensor data into a data block as part of an Electronic Product Code (EPC). E.g. when using an RFID standard implementation, 62 bytes per transmitted data block are available, and an on-board computational unit may be used for converting sensor data in appropriate data blocks.

In the further aspect, the control unit is arranged to select operation of the active radio transmitter, the backscatter radio transmitter or both the active radio transmitter and the backscatter radio transmitter, in a transmission mode for transmitting data to a host unit. The control unit may be further arranged to execute any one method embodiment as described herein.

The mobile transmitter device may further comprise an energy harvesting part connected to an energy storage unit, e.g. as part of the backscatter radio transmitter. Alternatively, the energy harvesting part is implemented as a separate module connected to the control unit.

In an even further embodiment, one or more peripheral components may be provided, e.g. a sensor, connected to the control unit. This would allow a very versatile and compact mobile sensing device as embodiment of the mobile transmitter device.

Short description of drawings

The present invention will be discussed in more detail below, using a number of exemplary embodiments, with reference to the attached drawings, in which

Fig. 1 shows a schematic diagram of a mobile transmitter device according to an embodiment of the present invention in communication with a host unit.

Detailed description of exemplary embodiments

Radio Frequency Identification (RFID) is a well known technique, which is normally used to identify or localize items provided with an RFID tag within a limited range. Furthermore, RFID devices are known which are provided with processing power, the so-called Computational RFID devices.

The article 'Design of an RFID-Based Battery-Free Programmable Sensing Platform', by Alanson P. Sample et al, IEEE Transactions on Instrumentation and Measurement, Vol. 57, no. 11, November 2008, which is incorporated herein by reference, describes an example of a Computational RFID device in the form of a battery free sensing and computational platform for sensor enhanced RFID

applications. A disadvantage of RFID communications is that the transfer is not very robust, and quite dependent on the distance between the RFID device and a host unit, and possible disturbances and/or interference in the communication path.

The present invention embodiments provide a new type of data transfer from a mobile transmitter device 1 to a host unit 9, as shown in the schematic diagram of Fig. 1. The host unit 9 is provided with suitable antennae 8a, 8b to receive

transmissions from the mobile transmitter device 1 in an appropriate manner. The mobile transmitter device 1 comprises an active radio transmitter 2 in combination with a backscatter radio transmitter 3. The backscatter radio transmitter 3 is e.g. a

Computational RFID (CRFID) device, and uses energy received by its antenna 8b to operate the backscatter radio transmitter 3, by 'reflecting' the received energy, e.g. in the form of an Electronic Product Code message. The active radio transmitter 2 is e.g. a Bluetooth or Bluetooth Low Energy (BLE) radio transmitter (IEEE 802.15.x) provided with a suitable antenna 8a.

As shown in Fig. 1, the mobile transmitter device 1 is further provided with a control unit 5, connected to the active radio transmitter 2 and the backscatter radio transmitter 3 (as indicated by the solid lines denoting power/energy flow, and dotted lines denoting control/data flow). According to the present invention embodiments, the control unit 5 is arranged to select operation of the active radio transmitter 2, the backscatter radio transmitter 3 or both the active radio transmitter 2 and the backscatter radio transmitter 3, in a transmission mode for transmitting data to a host unit 9. This allows to use the backscatter radio transmitter 3 whenever possible (when the circumstances allow for a robust data transmission to the host unit using the energy harvested by the backscatter radio transmitter 3), and using the active radio transmitter 2 otherwise or additionally. In the end, this will save energy and have an efficient as possible use of energy per transmitted byte of data, yet can also provide a robust and reliable data transmission. The control unit 5 may further be arranged to execute the method embodiments as described herein.

The control unit 5 may further be arranged to control supply of electrical power to the active radio transmitter 2 and/or the backscatter radio transmitter 3. E.g. the control unit 5 may be arranged to use a fixed power supply (e.g. a battery), or use the harvested energy, to directly power the active radio transmitter 2 and/or the backscatter radio transmitter 3. On their own, both the active radio transmitter 2 and the backscatter radio transmitter 3 have specific advantages but also disadvantages when desiring to use these for transmitting data to the host unit 9. An active radio transmitter 2 radiates energy into the air, but the energy consumption is relatively large. When looking at data transmission, in general the energy consumption per byte is constant over the transmission range. The backscatter radio transmitter 3 reflects energy (received mainly from the transmissions by the host unit 9), and usually the back and forward path loss in data communication is not alike. The energy consumption per byte increases with increasing communication path distance, and this is usually a limiting factor in attainable range and robustness of data transfer. It is known to increase performance of such backscatter radio transmitters 3 by adding a power supply (e.g. a battery).

In the present invention embodiments, the advantages of both subsystems in the mobile transmitter device 1 are combined. For that, the mobile transmitter device 1 is operated in a specific manner: selecting the backscatter radio transmitter 3 as an operative part of the mobile transmitter device 1 if a backscatter condition is fulfilled, the backscatter condition comprising that a channel quality indicator of a

communication channel between the backscatter radio transmitter 3 and the host unit 9 is higher than a predetermined quality threshold value. This ensure a high enough chance of successful data transmission to and reception at the host unit.

The channel quality indicator can be directly or indirectly derived from estimates or calculations of a probability of successful transmission over that channel. Examples include, but are not limited to, parameters which have a relation to the channel quality indicator:

- if multiple communication channels are used by either the active radio transmitter 2 or the backscatter radio transmitter 3, the quality on one of these channels may be used to provide a channel quality indicator to be used in the present embodiments;

- sensor data may be used, e.g. from a mobility detection sensor: if motion is detected, the channel quality indicator of the backscatter radio transmitter 3 is lowered, favoring a switch to the active radio transmitter 2. I.e. when a user is static, the backscatter radio transmitter 3 will be used, and when in motion the active radio transmitter 2 will be used (as that will provide a higher probability of successful transmissions; - situational parameters may be used: the channel quality indicator may be lowered in case of an emergency situation, again favoring a switch over to the active radio transmitter 2 with a higher probability of successful transmission of data;

- interference parameters may be used: if it is detected that a number of other backscatter radio transmitters 3 are used in the vicinity of the present mobile transmitter device 1 , the channel quality indicator may be lowered. Again, this will favor use of the active radio transmitter 2 in such circumstances, thus avoiding interference using the backscatter radio transmitter 3.

In a further embodiment, the active radio transmitter 2 is selected as operative if the backscatter condition is not fulfilled, and thus always one of the active radio transmitter 2 or the backscatter radio transmitter 3 is operating, which results in an efficient as possible use of energy in the mobile transmitter device 1. As an alternative, situations may be interpreted where both the active radio transmitter 2 and the backscatter radio transmitter 3 are operating, e.g. as a sort of diversity system in case of a lot of interference or other disturbances in the radio communication paths.

In addition, the backscatter condition may further comprise that the number of other nearby operating backscatter radio transmitters is lower than a predetermined number threshold value. The lower the number of other similar backscatter radio transmissions are received, the lower the risk will be of interfering transmissions, and the higher the chance of a successful transmission using the backscatter radio transmitter 3.

The channel quality indicator is e.g. measured in the backscatter radio transmitter 3, and is e.g. calculated or estimated based on previous data transmissions between the backscatter radio transmitter 3 and the host unit 9. In CRFID devices it is e.g. possible to monitor the number of Query and/or Acknowledge messages (and additionally or alternatively a packet loss rate) and use these as parameters for the channel quality indicator. In alternative embodiments, other messages may be used such as handshake messages, or reader broadcast messages. This measurement or estimation takes into account effects of the range of the data transmissions, the received power for a backscatter transmission and various interference possibilities.

As mentioned above, and illustrated in the exemplary embodiment shown in Fig. 1, the backscatter radio transmitter 3 comprises an energy harvesting part 4. The energy harvesting part 4 may comprise or be connected to an energy storage 7, from which supply power to the backscatter radio transmitter 3 can be provided. The energy harvesting part 4 and/or the energy storage 7 may also be units or devices separate from the backscatter radio transmitter 3. In the embodiment shown in Fig. 1, e.g. the energy storage 7 is connected to the control unit 5, and power flows also via the control unit 5.

The amount of energy stored in the energy storage 7 is monitored in a further embodiment, and the monitored amount of energy is then used as a further or additional backscatter condition for selecting operation of the active radio transmitter 2, the backscatter radio transmitter 3 or both the active radio transmitter 2 and the backscatter radio transmitter 3. This can result in an efficient as possible use of energy harvested by the present invention mobile transmitter device 1, thus obviating the need for a larger battery (energy storage 7) when a larger range or higher data rate is needed.

In a further specific operating mode, the mobile transmitter device 1 is operative using the active radio transmitter 2. In this group of embodiments, the backscatter radio transmitter 3 comprises an energy harvesting part 4 connected to an energy storage unit 7, and the method further comprises selecting the active radio transmitter 2 as an operative part of the mobile transmitter device 1 for transmitting data to the host unit 9, harvesting energy from the transmitted data by the energy harvesting part 4, and selecting the backscatter radio transmitter 2 as an operative part of the mobile transmitter device 1 for transmitting data to the host unit 9. [claim language of new claim 6]

When the active radio transmitter 2 sends a data message to the host unit 9, the energy radiated by antenna 8a is also picked up by the antenna 8b of the backscatter radio transmitter 3. The control unit 5 may control the backscatter radio transmitter 3 to harvest the energy associated with this transmission of the active radio transmitter 2. The harvested energy (stored in the energy storage 7) may then be used to execute a further data transmission using the backscatter radio transmitter 3, wherein the further data transmission is associated with the initial data transmission by the active radio transmitter 2. The further data transmission may comprise the same data as the initial data transmission, enhancing robustness of the data transmission to the host unit 9. Alternatively, the further data transmission may comprise other data which need to be transmitted to the host unit 9, enhancing the transmission efficiency, as a higher amount of data is transmitted to the host unit 9 without using additional energy. The control unit 5 may be arranged to control if and when this semi-parallel operating mode is activated for the mobile transmitter device 1.

The backscatter conditions can be programmed and stored in the mobile transmitter device 1 and the conditions can be checked e.g. using the control unit 5. Also the control unit 5 may be part of the backscatter radio transmitter 3, e.g. when implemented as a CRFID device or module. Furthermore, it would be possible to use a self-learning or machine learning algorithm for selecting the backscatter transmitter 3 and/or active radio transmitter 2. The machine learning algorithm can be trained to optimize energy consumption, transmission range and data rate for the mobile transmission device 1.

The backscatter condition can e.g. be one or more of the following parameters (possibly in combination):

• the amount of backscatter neighbors;

• the amount of successful messages;

· data acknowledgment rate;

• handshake rate;

• successful handshake rate

• difference between successful versus unsuccessful handshake rates;

• received signal strength indicator (RSSI);

· stored energy level (in energy storage 7);

• increase/decrease rate of stored energy;

• current data rate/ amount of data in transmit buffer.

Some parameters (see above) may be set by machine learning results. Some examples are as follows:

The mobile transmitter device 1 (control unit 5) can learn the correlation between channel quality of the active radio transmitter 2 and the channel quality of the backscatter radio transmitter 3 in a predetermined time duration. Based on this machine learning result, the mobile transmitter device 1 can anticipate whether the backscatter radio transmitter 3 is suitable for communication based on observing the channel quality of the active radio transmitter 2.

The mobile transmitter device 1 (control unit 5) can learn the correlation between the harvested power (e.g. RSSI) and the channel quality of backscatter radio transmitter 3. Based on this machine learning result, the mobile transmitter device 1 can anticipate whether the backscatter radio transmitter 3 is suitable for communication based on observing the harvested power.

In most applications, the mobile transmitter device 1 does not know the deployment of the host units 9 (i.e. the data aggregators). The deployment parameters (e.g. host unit density, host unit communication range, etc.) highly influences the selection of the backscatter radio transmitter 3 or the active radio transmitter 2 of the mobile transmitter device 1. In an embodiment, the mobile transmitter device 1 can learn the deployment parameters of the host units in a neighbouring area.

The mobile transmitter device 1 can learn the correlation between the sensor data and the channel quality of the backscatter radio transmitter 3 and the active radio transmitter 2. The mobile transmitter device 1 can learn how the mobility influences the channel quality of the backscatter radio transmitter 3, e.g. using an acceleration sensor. For example, if mobility and the channel quality of the backscatter radio transmitter 3 have a strong correlation (e.g. the mobility of the user can interrupt the backscatter radio channel with a high probability), then the mobile transmitter device 1 should use the active radio transmitter 2 having a high probability when mobile.

Based on the learned results in a time duration according to one or more options described above, the mobile transmitter device 1 can anticipate which radio 2, 3 is best suited for communication in a particular temporal and spatial condition and provide a high probability of successful communication. This anticipation can increase the accuracy that the mobile transmitter device 1 selects the most efficient radio transmitter 2, 3, and decrease the power consumption in switching between the active and backscatter radio transmitter 2, 3.

Furthermore, the mobile transmission device 1 may be arranged such that the active radio transmitter 2 is used to send channel statistics back to the host unit 9. E.g. when there is a request from the host unit for this type of data, the mobile transmission device 1 may switch over to the active radio transmitter 2 to ensure a high robustness and reliability of the channel statistics data being transmitted to the host unit.

Further alternatives for switching from the backscatter radio transmitter 3 to the active radio transmitter 2 can be as a backscatter condition indicating an importance or priority level of a message to be transmitted. Also, it would be possible to have the mobile transmission device 1 to randomly switch to the currently not used radio transmitter 2, 3, in order to prevent any possible starvation, life-locks or deadlock situations.

As shown in the embodiment of Fig. 1, the mobile transmission device 1 may further comprise one or more peripheral components 6, e.g. a sensor, connected to the control unit 5. In a further embodiment, the method further comprises

receiving sensor data and converting the sensor data into a data block as part of an Electronic Product Code (EPC). According to the RFID standards, 62 bytes of data are available per transmitted data block, when the 'normal' identification code of an RFID tag is replaced by actual data. The control unit 5, or alternatively an on-board computational unit of the backscatter radio transmitter 3 (CRFID variant) may be used to receive and convert sensor data in appropriate data blocks for transmission by the backscatter radio transmitter 3 (when selected as being active). Similar, this may also be applied when the active radio transmitter 2 is selected as active, using an appropriate data format for the protocol used by the active radio transmitter 2 (e.g. a Bluetooth or BLE module).

In a further group of embodiments, the active radio transmitter 2 and the backscatter radio transmitter 3 each comprise a diversity antenna arrangement 8a; 8b. A diversity antenna arrangement allows to improve the efficiency of the data transmission to/from the host unit 9, e.g. using multiple antennas to mitigate effects of possible interferers or other performance limiting circumstances, such as multi-path

interference. In a specific group of embodiments, the diversity antenna arrangement 8a, 8b comprises multiple antennae with mutually different orientations. The control unit 5 (or the active radio transmitter 2 itself) can then be arranged to select the best antenna from the diversity antenna arrangement, e.g. taking into account polarization direction and/or communication performance. In an even further specific embodiment, the antennae 8a of the active radio transmitter 2 are having the same orientation in the mobile communication device 1 as the antennae 8b of the backscatter radio transmitter 3. In other words, each antenna 8a has a parallel antenna 8b in the mobile

communication device 1. To establish the best efficiency communication from the mobile communication device 1 to the host unit 9, the control unit 5 may be arranged to select one of the antennae 8a of the active radio transmitter 2 and an associated one of the antennae 8b of the backscatter radio transmitter 3 as a combination for communication (see also the embodiment described above). The control unit 5 can be arranged to select the antenna combination that has the best communication efficiency, no matter how the orientation of the mobile communication device 1 is with respect to the (antennae 8a, 8b of) host unit 9. This would allow the mobile communication device 1 to be attached on the body of a person. At first, the person may stand in front of the host unit 9, and the control unit 5 searches and uses the antenna combination 8a, 8b, which has the best polarization direction and communication performance. Then the person may change position and e.g. lay in front of the host unit 9. The control unit 5 then again searches and uses the antenna combination 8a, 8b, which then has the best polarization direction and communication performance.

Using one of the invention embodiments as described above allows to improve the performance of a mobile transmission unit 1 , using as little energy per transmitted byte as possible. Yet, reliability and robustness of the data transmissions is maintained, in some embodiments independent from the distance of the data transmission to the host unit 9. In experimental set-ups this was measured, and the resulting performance was an equal achieved data rate substantially independent on range from 100-600cm. In similar circumstances, a backscatter radio transmitter 3 would only achieve such performance up to 300cm, and an active radio transmitter would only achieve such performance from 400cm and upwards.

Thus as illustrated and described above, the present invention embodiments allow to coordinate data transmissions using the two types of radio transmissions, in order to achieve a decreased power consumption compared to using an active radio transmitter 2 alone, while also increasing the range and/or reliability as compared to a backscatter radio transmitter 3 alone. This makes the present invention mobile transmission device 1 suitable for a large number of applications, including, but not limited to wearable devices e.g. for health monitoring, wireless medical hospital (smart) sensors (ECG, EEG, heart rate, etc.), warehouse inventory tracking and condition monitoring, indoor localization, crowd monitoring, etc. Furthermore it is noted that the proposed architecture of the embodiments as described above is not only limited to one active radio transmitter 2, and multiple active radio transmitters 2 may be used in a multi-radio device.

The present invention embodiments have been described above with reference to a number of exemplary embodiments as shown in the drawings. Modifications and alternative implementations of some parts or elements are possible, and are included in the scope of protection as defined in the appended claims.

Claims

1. Method of transmitting data from a mobile transmitter device (1) to a host unit (9),

the method comprising

using a combination of an active radio transmitter (2) and a backscatter radio transmitter (3) in the mobile transmitter device (1),

selecting the backscatter radio transmitter (3) as an operative part of the mobile transmitter device (1) if a backscatter condition is fulfilled,

the backscatter condition comprising that a channel quality indicator of a

communication channel between the backscatter radio transmitter (3) and the host unit (9) is higher than a predetermined threshold value.

2. Method according to claim 1, further comprising selecting the active radio transmitter (2) as operative if the backscatter condition is not fulfilled.

3. Method according to claim 1 or 2, wherein the backscatter condition further comprises that the number of other nearby operating backscatter radio transmitters is lower than a predetermined number threshold value.

4. Method according to any one of claims 1-3, wherein the channel quality indicator is calculated or estimated based on previous data transmissions between the backscatter radio transmitter (3) and the host unit (9).

5. Method according to any one of claims 1-4, wherein the backscatter radio transmitter (3) comprises an energy harvesting part (4) connected to an energy storage unit (7), and the method further comprises

monitoring the amount of energy stored in the energy storage unit (7), and using the monitored amount of energy as a further or additional backscatter condition for selecting operation of the active radio transmitter (2), the backscatter radio transmitter (3) or both the active radio transmitter (2) and the backscatter radio transmitter (3).

6. Method according to any one of claims 1-5, wherein the backscatter radio transmitter (3) comprises an energy harvesting part (4) connected to an energy storage unit (7), and the method further comprises

selecting the active radio transmitter (2) as an operative part of the mobile transmitter device (1) for transmitting data to the host unit (9),

harvesting energy from the transmitted data by the energy harvesting part (4), and selecting the backscatter radio transmitter (2) as an operative part of the mobile transmitter device (1) for transmitting data to the host unit (9). [same/further data]

7. Method according to any one of claims 1-6, wherein selecting the backscatter radio transmitter (3) and/or active radio transmitter (2) is based upon a machine learning algorithm.

8. Method according to any one of claims 1-7, wherein the active radio transmitter (2) is an IEEE 802.15.x transmitter.

9. Method according to any one of claims 1-8, wherein the backscatter radio transmitter (3) is an RFID transmitter, e.g. a Computational RFID transmitter.

10. Method according to any one of claims 1-9, further comprising

receiving sensor data and converting the sensor data into a data block as part of an Electronic Product Code (EPC).

11. Mobile transmitter device (1) comprising

an active radio transmitter (2),

a backscatter radio transmitter (3), and

a control unit (5) connected to the active radio transmitter (2) and the backscatter radio transmitter (3), the control unit (5) being arranged to select operation of the active radio transmitter (2), the backscatter radio transmitter (3) or both the active radio transmitter (2) and the backscatter radio transmitter (3), in a transmission mode for transmitting data to a host unit (9).

12. Mobile transmitter device (1) according to claim 1 1,

the control unit (5) being further arranged to execute the method according to any one of claims 1-10.

13. Mobile transmitter device (1) according to claim 11 or 12,

further comprising an energy harvesting part (4) connected to an energy storage unit

(V).

14. Mobile transmitter device (1) according to any one of claims 11-13, wherein the energy harvesting part (4) is a separate module connected to the control unit (5).

15. Mobile transmitter device (1) according to any one of claims 11-14, further comprising one or more peripheral components (6), e.g. a sensor, connected to the control unit (5).

16. Mobile transmitter device (1) according to any one of claims 11-15, the active radio transmitter (2) and the backscatter radio transmitter (3) each comprise a diversity antenna arrangement (8 a; 8b).

17. Mobile transmitter device (1) according to claim 16, wherein the diversity antenna arrangement (8a, 8b) comprises multiple antennae with mutually different orientations.