Adaptive compression of collection frames

Abstract

Method for transmitting measurements, implemented in a meter (1) and comprising the steps of: - detecting at least one period of constant consumption formed by successive time intervals during each of which the consumption is equal to a constant value; - producing and transmitting a collection frame containing the measurement data associated with the time intervals of the measurement period, by replacing, for each period of constant consumption, the measurement data associated with the successive time intervals of said period of constant consumption by compacted data comprising a first data item making it possible to identify the time intervals of the period of constant consumption and a second data item containing the constant value. FIGURE OF THE ABSTRACT: Fig.1

Description

Title of the invention: Adaptive compression of collection frames

[0001] The invention relates to the field of communicating meters: water, gas, electricity meters, etc.

[0002] BACKGROUND OF THE INVENTION

[0003] Modern water meters, also called "communicating water meters", of course include a measuring unit intended to measure the water consumption of an installation, but also a processing unit and a communication unit.

[0004] The processing unit acquires the measurements and allows the water meter to perform a certain number of functions, and in particular to analyze various data, relating for example to the water consumption of the installation, to the customer's billing, to the state of the water distribution network, or to the operation of the water meter itself.

[0005] The communication unit makes it possible to integrate the meter into a communication network, for example of the LPWAN type (for Low Power Wide Area Network, or low-consumption extended network), and to communicate with other entities of the network, and in particular with the Information System (IS) of the water supplier, possibly via a data concentrator, a gateway, or another meter (such as a communicating neighborhood water meter).

[0006] Each day, a water meter transmits to the IS at least one collection frame containing water consumption indexes of the installation to which the meter is connected.

[0007] The function of transmitting consumption indexes remotely is essential because it allows for better water management. Water suppliers use it to bill customers, to track water consumption in order to detect water leaks, excessive use and potential problems. Water suppliers can also adjust water production and distribution in real time according to demand, which can help reduce waste and optimize resources.

[0008] Each day is therefore divided into time intervals.

[0009] Each collection frame, produced by the processing unit and transmitted by the communication unit, is for example similar to that shown in the table in Appendix 1. The protocol used for communication is for example the DLMS protocol or the M-bus protocol. The collection frame contains, for each time interval, a measurement data item (consumption index). We see that in this collection frame, each time interval has a duration of 5 minutes, and that the measurement data item is the cumulative index (in liters). In a day, there are (24h * 60min) / 5 min = 288 time intervals. Each measurement data item has a size of 4 bytes, so that the size of the collection frame is at least 288 x 4 bytes = 1152 bytes. The size of the collection frame is generally even larger. Indeed, it is possible, for example, that control fields are present to indicate the number of indexes, the start time of the first index and the interval in hours between indexes. For the sake of simplicity, these control fields have been intentionally omitted.

[0010] The smaller the collection step (duration of a time interval), the more the water supplier can manage the network optimally, effectively detect leaks and optimize water distribution. Indeed, a fine resolution of the data allows for greater precision in detecting anomalies and variations in consumption, which facilitates the implementation of measures to reduce water losses and improve network efficiency.

[0011] However, reducing the collection step automatically increases the size of the collection frames.

[0012] However, it is known that the various electronic components of the water meter are powered by one or more batteries positioned in the meter. It is therefore appropriate to limit the electrical consumption of the electronic components of the water meter, to increase its lifespan. The wireless transmission of consumption data has a significant impact on the energy consumption of the meter. It is important to limit the electrical consumption of the communication unit in particular, which forces manufacturers to increase the duration of the time intervals of the collection frame to reduce its size, and thus to lose resolution.

[0013] Furthermore, longer collection frames require more time to be transmitted, which increases the congestion of the communication network and the risk of frame loss (which requires retransmission of the frames, and therefore further increases the congestion).

[0014] Thus, although a fine resolution of the collection step is very advantageous, this implies a large collection frame size and negatively impacts the electrical consumption of the meter and the congestion of the communication network.

[0015] SUBJECT OF THE INVENTION

[0016] The invention relates to a solution making it possible to reduce the size of the collection frames transmitted by a counter, without reducing the resolution of the measurements transmitted. Summary of the invention

[0017] With a view to achieving this aim, a method of transmitting measurements is proposed, implemented in a processing unit of a meter arranged to measure a quantity consumed by an installation during successive measurement periods, comprising the steps, for each measurement period, of:

[0018] - dividing said measurement period into time intervals;

[0019] - associate a measurement data item with each time interval, said measurement data item measurement being representative of consumption by the installation of the quantity during said time interval;

[0020] - detect, in said measurement period, at least one consumption period constant formed by successive time intervals during each of which consumption is equal to a constant value;

[0021] - produce and transmit a collection frame containing the measurement data associated with the time intervals of the measurement period, by replacing, for each period of constant consumption, the measurement data associated with the successive time intervals of said period of constant consumption by compacted data comprising at least a first data item making it possible to identify said successive time intervals of said period of constant consumption and a second data item containing the constant value corresponding to said period of constant consumption.

[0022] Based on the usual water consumption of households, it has been found that a "normal" day includes a certain number of periods of constant consumption. These periods generally correspond to times when water is not consumed, for example in the evening or during working hours. This can also correspond to small leak rates that are constant over time.

[0023] The existence of these periods of constant consumption can be observed for any quantity measured by any type of meter: gas meter, electricity meter, etc.

[0024] The method for transmitting measurements therefore consists of detecting these periods of constant consumption in each measurement period, and of compacting in the collection frame the measurement data associated with the time intervals of said periods of constant consumption. A collection frame of reduced size is therefore obtained without reducing the resolution of the transmitted data.

[0025] A method for transmitting measurements as previously described is further proposed, comprising the step of verifying, for each period of constant consumption, that a size of the compacted data is less than a size of the measurement data associated with the successive time intervals of said period of constant consumption, and of replacing the measurement data with the compacted data only if this is the case.

[0026] We further propose a method for transmitting measurements as previously described, further comprising the step, for each measurement period, of defining an optimal duration of the time intervals, the optimal duration being the smallest duration which makes it possible to maintain a size of the collection frame less than or equal to a predefined maximum size, said measurement period then being divided into in- time intervals having the optimal duration.

[0027] We further propose a method for transmitting measurements as previously described, further comprising the step of allocating, to each measurement data item, the same data size obtained from a maximum value of the measurement data over said measurement period.

[0028] We further propose a method for transmitting measurements as previously described, in which, for each time interval, the measurement data is equal to the consumption by the installation of the quantity during said time interval.

[0029] A meter is further proposed comprising a communication unit and a processing unit in which the method for transmitting measurements as previously described is implemented, the communication unit being arranged to transmit the collection frames to an entity external to the meter.

[0030] A meter as previously described is further provided, the meter being a fluid meter.

[0031] A computer program is further provided comprising instructions which cause the processing unit of the meter as previously described to execute the steps of the measurement transmission method as previously described.

[0032] A computer-readable recording medium is further provided, on which the computer program as previously described is recorded.

[0033] The invention will be better understood in light of the following description of a particular non-limiting embodiment of the invention. Brief description of the drawings

[0034] Reference will be made to the attached drawings, among which:

[0035] [Fig-1] [Fig.l] represents a water meter, a distribution network and an ins installation powered by said network;

[0036] [Fig.2] [Fig.2] represents a graph comprising a curve of the daily water consumption of an apartment;

[0037] [Fig.3] [Fig.3] represents the steps of a duration definition process optimal time intervals;

[0038] [Fig.4] [Fig.4] represents the steps of a process of calculating the size of a collection frame. DETAILED DESCRIPTION OF THE INVENTION

[0039] With reference to [Fig.l], a water meter 1 is used to measure the volume of water consumed by an installation 2. The water is supplied to the installation 2 by a water distribution network 3.

[0040] The counter 1 comprises a measuring unit 4, a processing unit 5 and a communication unit 6.

[0041] The measuring unit 4 comprises, for example, an ultrasonic measuring device which makes it possible to estimate the flow rate of water consumed and therefore the volume of water consumed.

[0042] The processing unit 5 is an electronic and software unit. The processing unit 5 comprises at least one processing component 7, which is for example a “generalist” processor, a processor specialized in signal processing (or DSP, for Digital Signal Processor), a processor specialized for artificial intelligence algorithms (of the NPU type, for Neural Processing Unit), a microcontroller, or a programmable logic circuit such as an FPGA (for Field Programmable Gate Arrays) or an ASIC (for Application Specific Integrated Circuit).

[0043] The processing unit 5 also comprises one or more memories 8, connected to or integrated in the processing component 7. At least one of these memories 8 forms a computer-readable recording medium, on which is recorded at least one computer program comprising instructions which cause the processing unit 5 to execute at least some of the steps of the measurement transmission method which will be described.

[0044] The processing unit 5 implements a certain number of functionalities. Among these, the processing unit 5 acquires the measurements made by the measurement unit 4, processes and formats said measurements, and produces collection frames from these measurements. The collection frames are then transmitted to the IS 10 by the communication unit 6.

[0045] The meter 1 therefore measures the volume of water consumed by the installation 2 during successive measurement periods.

[0046] The measurement periods here each last one day, i.e. 24 hours, and begin at OOhOO (00:00) and end at 23:59 (23:59).

[0047] After each measurement period, the processing unit 5 produces a collection frame from the measurements made by the measurement unit 4 during said measurement period.

[0048] According to data provided by the water agencies and ADEME (Agence de la transition écologique), which are French public institutions, the average consumption of drinking water in France for a household of four people is approximately 120 liters per day per person.

[0049] Even if water consumption varies considerably depending on the habits of each household and its equipment (number of people, sanitary equipment, household appliances, garden, etc.), the consumption profile systematically presents areas of non-consumption.

[0050] By non-consumption, we mean two cases: - no consumption (i.e. zero flow); - stable consumption (e.g. a small potential leak, which is stable in time).

[0051] The typical daily consumption for a two-person apartment, shown in the graph in [Fig.2], shows that for at least 80% of the time, the variation in consumption is constant. This information is important because it is the entry point for the measurement transmission method described here.

[0052] This observation is not surprising, because households do not consume continuously. Continuous consumption is observed only in specific cases (factory, water fountain, water leak).

[0053] For each measurement period, the processing unit 5 first acquires all the measurements carried out by the measurement unit 4 during said measurement period.

[0054] Then, the processing unit 5 divides each measurement period into time intervals.

[0055] The processing unit 5 associates a measurement datum with each time interval, said measurement datum being representative of a consumption of water volume by the installation 2 during said time interval.

[0056] The measurement data could be absolute cumulative indexes (as for the measurement frame of Appendix 1).

[0057] Here, however, for each time interval (except for the first), the measurement data is equal to the consumption by the installation of the quantity (volume of water) during said time interval. Thus, rather than sending absolute cumulative indexes, the processing unit 5 calculates the difference in index between two moments, also called “delta index”, i.e. the index at time “t” minus the index at time “t-1”. In this way, the size allocated for each delta will be less than that allocated for a cumulative index (4 bytes for example for the cumulative index).

[0058] The processing unit 5 then allocates, to each measurement data item, the same data size obtained from a maximum value of the measurement data over said measurement period.

[0059] The allocated data size is therefore calculated dynamically for each day based on the consumption deltas. By calculating all the deltas and selecting the maximum, we can determine the size to be allocated, for each delta, based on this maximum value.

[0060] The processing unit 5 uses the following formula:

[0061] data size = number of bits allocated per time interval = roundsuP (logvpelta |)) + 1 \' max

[0062] where Deltamax is the maximum value of the measurement data over said measurement period.

[0063] Thus, for example, if the maximum value of the measurement data over a period of measurement is 30 liters for a 5-minute step (time interval), then the processing unit 5 allocates 6 bits to each measurement data (except for that associated with the first time interval of the day, between 00:00 and 00:05). The 6 bits include a sign bit to cover the case of backflow (negative consumption) which is taken into account by some water suppliers. The "+ 1" in the formula above allows the sign bit to be taken into account.

[0064] Thus, the size of the collection frame goes from 1152 bytes to 220 bytes, i.e. an 80% reduction in the size of the useful data.

[0065] The collection frame obtained could then be similar to that of Appendix 2. The measurement data associated with the first time interval has a size of 4 bytes, because it contains the cumulative index of water consumed.

[0066] On the other hand, the other measurement data have a size of 6 bits.

[0067] However, as we have just seen, based on the water consumption ha In the household water consumption study, it was observed that 80% of the time, the difference in consumption is constant. These periods correspond to times when water is not generally used, such as in the evening or during working hours. This also corresponds to small leak rates that are constant over time.

[0068] It is therefore particularly advantageous to compress these constant difference values ​​in order to further reduce the size of the collection frame.

[0069] Thus, for each measurement period, the processing unit 5 detects, in said measurement period, at least one period of constant consumption formed by successive time intervals (at least two) during each of which the consumption is equal to a constant value. [Fig.2] shows periods of constant consumption Pc.

[0070] A day includes, for example, a period of constant consumption between 01:00 and 01:20 (i.e. four successive time intervals), another period of constant consumption between 04:30 and 04:55 (i.e. five successive time intervals), etc. For these two periods of constant consumption, the consumption may be zero (constant value = 0 L), or non-zero in the case of a small constant leak.

[0071] Periods of constant consumption are detected dynamically and therefore vary according to the measurement periods.

[0072] The processing unit 5 then produces and transmits a collection frame containing the measurement data associated with the time intervals of the measurement period, by replacing, for each constant consumption period, the measurement data associated with the successive time intervals of said constant consumption period with compacted data comprising at least a first piece of data making it possible to identify said successive time intervals of said constant consumption period. constant consumption and a second data item containing the constant value corresponding to said period of constant consumption.

[0073] Here, the compacted data includes, for each identified constant consumption period:

[0074] - two first data allowing the identification of successive time intervals of said constant consumption period. This first data is the identifier of the first time interval of the constant consumption period (data size: 2 bytes), and the number of successive time intervals of the constant consumption period (data size: 1 byte);

[0075] - a second data item containing the constant value associated with the period of constant consumption, i.e. here the constant index delta (data size: 2 bytes).

[0076] We therefore obtain, for each period of constant consumption, a metadata coded on 5 bytes.

[0077] Advantageously, the processing unit 5 verifies, for each period of constant consumption, that a size of the compacted data is much smaller than a size of the measurement data associated with the successive time intervals of said period of constant consumption, and replaces the measurement data with the compacted data only if this is the case.

[0078] Thus, if the size of a metadata is greater than the area to be removed, the algorithm does not delete the area and keeps the measurement data of the area.

[0079] When the SI 10 receives the collection frame, it begins by processing the metadata to obtain the original deltas.

[0080] Advantageously, the processing unit 5 defines an optimal duration of the time intervals. The optimal duration is the smallest duration which makes it possible to maintain a size of the collection frame less than or equal to a predefined maximum size. The processing unit 5 then divides said measurement period into time intervals having the optimal duration as their duration, and produces the collection frame using time intervals each having the optimal duration as their duration.

[0081] Thus, depending on the measurement periods, the duration of the time intervals can vary. The shorter the time intervals, the higher the resolution of the collected measurements, but the larger the size of the collection frame.

[0082] The optimal duration is therefore the smallest duration which allows the size of the collection frame to be kept less than or equal to the predefined maximum size.

[0083] In the context where the maximum size of the payload of the measurement frame is limited, a compression algorithm is therefore used to adjust the resolution of the measurements in order to maximize the number of indexes transmitted while remaining below this fixed limit.

[0084] The general idea is that the compression algorithm can iterate through the data to be compressed and vary the resolution of the measurements. The algorithm can then evaluate the number of indexes generated using different resolutions and select the one that maximizes the number of indexes while ensuring that the total payload size remains below the specified limit.

[0085] By intelligently adjusting the measurement resolution, the algorithm can find a trade-off between data accuracy and payload size.

[0086] We now turn to the implementation of the invention by describing two processes: a process for defining the optimal duration of the time intervals, and a process for calculating the size of the collection frame. These two processes are presented separately to improve understanding of the method.

[0087] With reference to [Fig.3], we first present an example of an algorithm used to implement the process of defining the optimal duration of the time intervals.

[0088] This process uses the process of calculating the size of a collection frame, which will be described below.

[0089] The algorithm of [Fig.3] makes it possible to define the optimal duration of each time interval for the transmission of data according to a predefined maximum size L of the collection frame, which is the size not to be exceeded.

[0090] For example, L = 255 bytes.

[0091] The algorithm uses the variables: - Current duration D of time intervals; - Current size 1 of the collection frame.

[0092] The process begins with a step of defining the initial configuration: step EL The initial configuration is defined with the following parameters.

[0093] The predefined maximum size is equal to L = 255 bytes. The optimal duration D0 of each time interval is initialized to 0. The maximum duration Dmax of a time interval is 24 hours.

[0094] Then, the current duration D is initialized with the value Dmax:

[0095] D = Dmax (step E2).

[0096] The processing unit 5 then calculates the current size 1 of the collection frame using the current duration D (step E3). The processing unit 5 uses for this calculation the process for calculating the size of a collection frame which will be described below. This function is called “Compute (D)” here.

[0097] The processing unit 5 then compares the current size 1 of the collection frame with the predefined maximum size L (step E4).

[0098] If the current size 1 is less than the predefined maximum size L (here strictly less), the processing unit 5 saves the current duration D as duration optimal DO:

[0099] DO = D (step E5).

[0100] The processing unit 5 then reduces the current duration D:

[0101] D = D / 2.

[0102] Then, the process returns to step E3.

[0103] In step E4, if the current size 1 is greater than the predefined maximum size L (here greater than or equal), the process ends (step E6). The optimal duration D0 has been identified.

[0104] This algorithm can be implemented in the following manner:

[0105] intmain(){

[0106] int L = 255;

[0107] int Pmin = 1 ; / / Unit: minutes

[0108] int Pmax = 24*60; / / Unit: minutes

[0109] intPo = 0;

[0110] for (int P = Pmax; P >= Pmin; P / = 2) { [YES] int 1 = compute(P);

[0112] if (1 < L) {

[0113] Po = P;

[0114] } else {

[0115] break;

[0116] }

[0117] }

[0118] printf("The optimal value of Po is: %d\n", Po);

[0119] return 0;

[0120] }

[0121] We now describe, with reference to [Fig.4], an example of an algorithm used to implement the process of calculating the size of the collection frame (“Compute (D)”). This process also makes it possible to produce the collection frame.

[0122] We use the operations previously described: calculation of the measurement data, of the size allocated to each measurement data, and of the metadata.

[0123] The process therefore begins with the calculation of the measurement data, i.e. here the variations in consumption between the measurement intervals of the measurement period (step E10).

[0124] Then, the processing unit 5 calculates the data size allocated to each measurement data, i.e. the number of bits necessary to represent each index delta (step Eli).

[0125] The processing unit 5 then iterates over the content of the collection frame and scans each element of the collection frame to perform the compression operations. (step El2).

[0126] The processing unit 5 identifies the periods of constant consumption (step E13).

[0127] The processing unit 5 produces for each period of constant consumption the compacted data and compares the size of the measurement data of each constant consumption period with the size of a metadata Lm (step El4).

[0128] If the size of the measurement data of the constant consumption period is greater (here strictly greater) than the size of a metadata, the processing unit 5 uses said metadata to produce the collection frame (step El5).

[0129] The processing unit 5 checks whether the process has reached the end of the collection frame (step E16). If this is not the case, the process returns to step E12.

[0130] If this is the case, the processing unit returns the calculated size of the collection frame (step El7).

[0131] In step E14, if the size of the measurement data of the constant consumption period is less (here less than or equal to) the size of a metadata, the processing unit 5 does not use the metadata and retains the measurement data of the constant consumption period in the collection frame. The process proceeds to step E16.

[0132] The invention therefore makes it possible to compress the collection data in order to maintain a high measurement resolution while reducing the quantity of data to be transmitted.

[0133] We therefore reduce the amount of data to be transmitted while maintaining sufficient resolution. We maximize the amount of useful information in a collection frame. We reduce the energy impact of the collection frames in a communicating meter.

[0134] The invention therefore proposes a method of adaptive compression of the collection frame in order to reduce its size while retaining the most important information on water consumption.

[0135] The invention proposes to study the water index data collected by the meter, calculate the index deltas and compress them using an appropriate compression algorithm.

[0136] The invention makes it possible to maximize the quantity of useful information in a given collection frame by adjusting, if necessary, the index measurement step.

[0137] The implementation of the invention is very simple. Thanks to this “tailor-made” approach, it makes it possible to obtain a better conversion rate than standard compression methods.

[0138] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0139] The method of transmitting measurements can be implemented in any type of meter: fluid meter (water, gas, oil, etc.), electricity meter, etc. For electric meters, reducing the electricity consumption of said meters by implementing the method is not necessarily very advantageous, because these are generally supplied by the electricity distribution network. On the other hand, as we have seen, the method also makes it possible, by reducing the size of the collection frames, to reduce the congestion of the communication network, which is very advantageous even for an electric meter.

[0140] The measurement periods are not necessarily days.

[0141] The measurement data are not necessarily each equal to the consumption by the installation of the quantity during a time interval. This could be cumulative consumption. In this case, the compacted data may include data that identify the time intervals of the constant consumption period, the constant consumption value corresponding to said constant consumption period, as well as the consumption value at the beginning of the first interval of the constant consumption period. Annex 1

[0142] format of a collection frame Cumulative Index (L) Index Size (bytes) Index @ 00:00 12060 4 Index @ 00:05 12064 4 Index @ 00:10 12064 4 Index @ 23:55 12184 4 Annex 2

[0143] format of a collection frame with delta index Index (L) Size (bits) Index @ 00:00 12060 4*8 Delta Index @00:05 - Index@00:00 4 6 Delta Index @00:10 - Index @ 00:05 30 6 Delta Index @23:55 - Index @ 23:50 2 6

Claims

Claims

1. Method for transmitting measurements, implemented in a processing unit (5) of a meter (1) arranged to measure a quantity consumed by an installation (2) during successive measurement periods, comprising the steps, for each measurement period, of: - dividing said measurement period into time intervals; - associating a measurement datum with each time interval, said measurement datum being representative of a consumption by the installation (2) of the quantity during said time interval; - detecting, in said measurement period, at least one period of constant consumption (Pc) formed by successive time intervals during each of which the consumption is equal to a constant value;- produce and transmit a collection frame containing the measurement data associated with the time intervals of the measurement period, by replacing, for each constant consumption period (Pc), the measurement data associated with the successive time intervals of said constant consumption period with compacted data comprising at least a first data item making it possible to identify said successive time intervals of said constant consumption period and a second data item containing the constant value corresponding to said constant consumption period.;

2. Method for transmitting measurements according to claim 1, comprising the step of verifying, for each period of constant consumption, that a size of the compacted data is less than a size of the measurement data associated with the successive time intervals of said period of constant consumption, and of carrying out the replacement of the measurement data by the compacted data only if this is the case.

3. Method for transmitting measurements according to one of the preceding claims, further comprising the step, for each measurement period, of defining an optimal duration of the time intervals, the optimal duration being the smallest duration which makes it possible to maintain a size of the collection frame less than or equal to a predefined maximum size, said measurement period then being divided into time intervals having the optimal duration as their duration.

4. Method for transmitting measurements according to one of the preceding claims- preceding, further comprising the step of allocating, to each measurement data, the same data size obtained from a maximum value of the measurement data over said measurement period.

5. Method for transmitting measurements according to one of the preceding claims, in which, for each time interval, the measurement data is equal to the consumption by the installation of the quantity during said time interval.

6. Meter (1) comprising a communication unit (6) and a processing unit (5) in which the method for transmitting measurements according to one of the preceding claims is implemented, the communication unit being arranged to transmit the collection frames to an entity (10) external to the meter (1).

7. A meter according to claim 6, the meter being a fluid meter.

8. Computer program comprising instructions which cause the processing unit (5) of the meter according to one of claims 6 or 7 to execute the steps of the method for transmitting measurements according to one of claims 1 to 5.

9. A computer-readable recording medium on which the computer program according to claim 8 is recorded.

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