Redundancy-free wireless transmission of meter data

Technical solution proposal H2018-059
Business unit: Diehl Metering Systems GmbH
 

Technical field

The present invention relates to a method and an associated device for transmitting consumption data from a measuring device, in particular an energy, water, gas or heat meter, to a remote receiving device via a radio channel.

In known radio meter systems, consumption data is typically repeated at regular intervals and transmitted without explicit acknowledgement of receipt. This approach is particularly established in systems such as those in accordance with standard EN 13757-4 or corresponding OMS specifications. The repeated transmission of identical data serves to increase the probability of reception, but leads to considerable redundancy in the transmitted data. This results in increased radio traffic and higher energy consumption by the meter, which is particularly disadvantageous in the case of battery-powered devices. Furthermore, in such systems, the meter has no knowledge of whether and which consumption data have actually been successfully received.

Object of the invention
The invention is therefore based on the task of providing a method and a device by which consumption data from a measuring device can be transmitted reliably and with significantly reduced redundancy via a radio channel . In doing so, the energy consumption of the meter is to be reduced whilst ensuring high data integrity and temporal accuracy of the transmitted consumption values.

Description of the invention
This task is solved by a method according to the invention, in which the meter transmits consumption data to a gateway and receives, preferably, an authenticated acknowledgement from the gateway regarding the successful receipt of the transmitted data. Based on this acknowledgement, the meter manages an internal data status indicating which consumption data has been successfully transmitted and which is still pending.

This has the effect that, during the next transmission, the meter specifically retransmits only those consumption data for which no acknowledgement of receipt has yet been received. This takes place in a largely redundancy-free data transmission. The advantage is that the data volume in the radio channel is significantly reduced, thereby improving both the battery life of the meter and the utilisation of the radio channel.

According to the invention, there is a reversal of responsibility within the transmission system. Whilst in the prior art the gateway or a central system is responsible for ensuring data completeness, according to the invention the meter itself actively takes over the management and control of the application data to be transmitted. This means that the meter knows exactly which data has been successfully transmitted. The advantage is targeted, demand-driven transmission without unnecessary repetitions.

The invention is particularly suitable for use in modern wireless metering systems with bidirectional communication, for example in smart metering systems for energy, water or gas networks. It can be implemented both in new devices and, by adapting the firmware accordingly, in existing bidirectional meters.

In a preferred embodiment, the meter records consumption data in time-defined registers, for example at intervals of 15 minutes or several hours. The meter stores this register data together with time information, preferably using an internal clock or a regularly synchronised clock. This ensures that the consumption data can be generated and transmitted with precise timing. The advantage is that the receiving systems, in particular head-end systems, can use the data immediately for time-dependent applications such as tariffing or load profiling.

If, following a transmission, no acknowledgement is received from the gateway within a defined period, the meter can be configured to transmit both new consumption data and the previously unacknowledged data at the next regular transmission time. This results in increased transmission reliability even in the event of temporary radio interference, whilst still avoiding the resending of data that has already been acknowledged.

In a further preferred embodiment, the meter manages a so-called upload register set, which maps the transmission status of individual time intervals. This enables the meter to respond flexibly to successful or failed transmissions by applying alternative transmission schedules. The advantage is increased robustness of the overall system whilst simultaneously optimising radio communication.

Description of the Figures

Examples of implementation are explained in more detail below with reference to two figures.

Fig. 1  shows a measurement data upload

Fig. 2  shows an upload schedule

Figure 1 shows a measurement data upload, with the following steps

• The ACKs place an additional load on the downlink.

• ACKs must be authenticated, or

• only LL-ACKs, but with secure settlement at the end of the day via request/response.

• The data is less up-to-date

• The system’s responsiveness for bidirectional communication is increased by sending ACC_NR at shorter intervals

• The counter’s clock is used for timestamping ➔ Time synchronisation of the counter is required.

• The size of the SND_UD frame increases as transmissions are less frequent. It increases with every missing ACK.

• Based on the bidirectional communication pattern ➔ Complexity increases

Figure 2 shows an example of a water meter with a meter reading based on a 3-hour interval.

The upload schedule may, for example, specify that four values are normally uploaded twice a day.

The upload times could be 10 am and 10 pm. The upload at 10 am was successful, so the readings up to 9 am are correct. The upload at 10 pm was unsuccessful, so the remaining readings are missing. The meter can respond with pre-prepared alternative upload schedules, e.g. repeat this message three times after a 10-minute wait. If this also fails, the meter can send 8 values at 10 am the following day. This means that the meter manages the contents of the frames itself based on the meter data upload register.

1. Method for transmitting consumption data from a meter via a bidirectional radio link to a receiving device, wherein the meter determines consumption data and stores it in successive time intervals and transmits this consumption data in the form of radio messages, characterised in that, after transmitting consumption data, the meter receives an acknowledgement of receipt—preferably cryptographically authenticated—sent by the gateway confirming the successful receipt of the transmitted consumption data, updates an internal transmission status of the individual consumption data on the basis of this acknowledgement of receipt and, upon a subsequent transmission of consumption data, only retransmits such consumption data for which no acknowledgement of receipt is available.
2. A method according to claim 1, characterised in that the internal transmission status is maintained in the form of a data register managed by the meter, in which a status value is stored for each data interval, indicating whether the associated consumption data has been successfully transmitted.
3. A method according to claim 1 or 2, characterised in that the consumption data is generated at defined time intervals, preferably at intervals of several minutes or several hours, and is provided with time information in each case.
4. A method according to one of the preceding claims, characterised in that the meter has an internal real-time clock or is regularly synchronised with an external time source, wherein this time information is used for the time-accurate generation and assignment of the consumption data.
5. A method according to one of the preceding claims, characterised in that, if no acknowledgement of receipt is received within a specified period, the meter retransmits both newly generated consumption data and those consumption data whose transmission status is marked as unconfirmed during the next regular transmission process.
6. A method according to one of the preceding claims, characterised in that the meter selects or generates alternative transmission schedules based on the internal transmission status, in particular by adapting the number and scope of the consumption data to be transmitted to the number of previously unacknowledged transmissions.
7. A method according to one of the preceding claims, characterised in that the acknowledgement contains information as to which of the transmitted consumption data has been successfully received, and that the meter uses this information to selectively update the internal transmission status.
8. A method according to one of the preceding claims, characterised in that the amount of data transmitted via the radio channel is reduced by selectively retransmitting only unacknowledged consumption data, thereby reducing the energy consumption of the meter.
9. A meter for transmitting consumption data via a radio channel, comprising a measuring device for recording consumption values, a storage device for storing time-stamped consumption data, a radio transmitting device and a receiving device, as well as a control device, wherein the control device is designed to execute a method according to any one of claims 1 to 8.
10. A system for transmitting consumption data, comprising at least one meter according to claim 9 and a gateway, wherein the gateway is configured to process received consumption data and to send a confirmation of receipt back to the meter regarding the successful receipt of the consumption data, so that the meter controls the content of subsequent transmissions based on the confirmed transmission status

Abstract

A method for transmitting consumption data from a meter via a bidirectional radio link to a receiving device, wherein the meter determines consumption data and stores it in successive time intervals and transmits this consumption data in the form of radio messages, characterised in that, after transmitting consumption data, the meter receives an acknowledgement of receipt—preferably cryptographically authenticated—sent by the gateway confirming the successful receipt of the transmitted consumption data, updates an internal transmission status of the individual consumption data on the basis of this acknowledgement of receipt, and, upon a subsequent transmission of consumption data, retransmits only such consumption data for which no acknowledgement of receipt is available.