Method for operating a node in a wireless network - Patents.com
Patent Information
- Application Number
- JP2024514042
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-01-21
- Filing Date
- 2022-08-19
- Publication Date
- 2025-08-19
- Estimated Expiration
- 2042-08-19
AI Technical Summary
The challenge is to reduce the manufacturing cost of nodes in wireless networks while maintaining performance, particularly in energy-independent nodes using non-rechargeable batteries with limited lifespans, by optimizing energy consumption and buffer management.
Implementing pauses between radio bursts, forming radio burst clusters, adjusting transmission intervals, and using less expensive energy buffers such as electrolytic capacitors to manage energy consumption effectively.
This approach reduces manufacturing costs by allowing the use of cheaper energy buffers without compromising performance, ensuring the energy buffer remains above the operating voltage threshold, thereby extending the lifespan of nodes.
Smart Images
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Abstract
Description
[Technical field]
[0001] The invention relates to a method for operating a node in a wireless network according to the preamble of claim 1. The invention also relates to a node of a wireless network according to the preamble of claim 24. [Background technology]
[0002] The present invention relates to a method for operating an energy-independently operated node in a wireless network, preferably of the type described in ETSI TS 103357 V1.1.1 (2018-06). This is a wireless network that uses unlicensed frequency bands. In such a network, a number of nodes, in particular end nodes, are provided that communicate with a base station over the air, either on the uplink only or on the uplink and downlink. The nodes can be sensor devices for collecting any kind of data, actuator devices for carrying out some actions or measures, or a combination of sensor and actuator devices. Such nodes are operated by a dedicated, i.e. autonomous, power source in the form of a non-rechargeable hardwired long-life battery that has a limited life depending on the individual energy consumption of the node, is not rechargeable and must be replaced at the end of its life. In normal circumstances, such a battery can be used to achieve a life of at least 10 years "in the field" before replacement is required.
[0003] An energy buffer is used in the node to buffer energy from the battery, from which the power consumer (e.g., the receiver or transceiver of the node) obtains the required power. In a bidirectional communication, for example, a telegram is first transmitted from the base station to the node on the downlink after the node's telegram has been transmitted on the uplink. The telegram or data packet is "split", i.e. decomposed into individual sub-data packets, which are then continuously received on the downlink or sent out on the uplink as "radio bursts" or "radio burst clusters" with a time transmission interval T_RB(s). A radio burst has a length of about 12-22 ms on the downlink and about 15 ms on the uplink. According to ETSI TS 103357 V1.1.1 (2018-06), the time transmission interval T_RB(s) of adjacent radio bursts is on average about 230 ms on the downlink and on average about 150 ms on the uplink. The sub-data packets may be sent individually in a single frequency channel or, alternatively, on different frequencies or frequency channels. According to ETSI TS 103357 V1.1.1 (2018-06), it is proposed to combine the radio bursts in blocks of extended frames comprising multiple radio bursts on the downlink and to receive them with pauses ΔT_dn between the blocks. The standard also specifies pauses ΔT_Tsi between the core frame and the extended frame. The pauses ΔT_dn (block pauses) and ΔT_Tsi (frame pauses) can be up to 7,168 symbols or 65,532 symbols long. This corresponds to 3.011 seconds for ΔT_dn and 27.53 seconds for ΔT_Tsi. [Prior art documents] [Non-patent literature]
[0004] [Non-Patent Document 1] ETSI TS 103357 V1.1.1(2018-06) Summary of the Invention [Problem to be solved by the invention]
[0005] An object of the present invention is to reduce the manufacturing cost of a node while maintaining the performance of the node. [Means for solving the problem]
[0006] The above object is achieved by a method according to claim 1 and a node according to claim 24. Advantageous embodiments of the method according to the invention are specified in the dependent claims.
[0007] According to the invention, it is provided that at least two, preferably several pauses are provided, each pause being provided between two adjacent radio bursts and in each case longer than 7,168 symbols based on a symbol rate of 2,380,371 sym / s. A pause is a time window during which the transmission process of a radio burst is interrupted or stopped. This means that the pause is not a pause between two frames (in particular a core frame and an extended frame), defined as ΔT_si in ETSI TS 103357 V1.1.1 (2018-06), nor a transmission interval between two adjacent radio bursts, defined as radio burst time T_RB(s) in ETSI TS 103357 V1.1.1 (2018-06).
[0008] Alternatively or additionally, the present invention provides that the radio bursts are combined into radio burst clusters, the radio bursts in the radio burst clusters being transmitted and / or received consecutively, each in a time transmission interval, and that at least one radio burst cluster on the uplink comprises less than 24 radio bursts and / or at least two radio burst clusters on the downlink comprise less than 18 radio bursts.
[0009] Alternatively or additionally, the present invention provides that the time transmission interval (T_RB(s)) is greater than 655 symbols based on a symbol rate of 2,380,371 sym / sec.
[0010] When a radio burst is received or sent, energy is drawn from the energy buffer, which temporarily reduces the voltage of the energy storage device until it is recharged from the battery. By the above measures, individually or in combination, the energy buffer can be effectively protected with respect to its discharge behavior, so that a particularly inexpensive energy buffer can be used. This allows production costs to be effectively reduced without compromising performance.
[0011] A respective pause may in particular be provided between two adjacent radio bursts of a frame, preferably a core frame and / or an extended frame.
[0012] In particular, a radio burst cluster may also be formed by dividing a block of individual radio bursts into at least two radio burst clusters separated by a pause, where a block pause may be maintained between the blocks.
[0013] A pause is preferably provided between two adjacent radio bursts of a frame, each belonging to a different radio burst cluster.
[0014] The radio burst clusters separated by respective pauses may each comprise the same number of radio bursts.
[0015] Preferably, the number of radio bursts per block predefined according to ETSI TS 103357 V1.1.1 (2018-06) may be divided into integer numbers in order to reduce the load on the energy buffer for generating the number of radio bursts in each radio burst cluster.
[0016] Preferably on the uplink, the pause may be omitted in the first part of the data packet or the frame of the data packet and the pause may be provided in the second part of the data packet or the frame of the data packet, or the pause may be provided in the first part of the data packet or the frame of the data packet with a shorter length than in the second part of the data packet or the frame of the data packet.
[0017] For example, the core frame may omit a pause, while the extension frame may include a pause, or both the core frame and the extension frame may include a pause, with the pause in the core frame being dimensioned shorter than the pause in the extension frame.
[0018] Advantageously, the location or distribution of each pause within a data packet or frame and / or the length of each pause and / or the number of radio bursts per radio burst cluster and / or the number of symbols per radio burst are predefined such that the coherence time is maintained.
[0019] Thus, radio bursts of at least one radio burst cluster may be within the coherence time, preferably radio bursts of at least two radio burst clusters on the uplink may be within the coherence time, and / or fewer radio burst clusters may be within the coherence time in a first part of a data packet transmission than in a second part of the transmission.
[0020] Advantageously, the accuracy of the node's crystal and / or the base station's crystal may be included in the dimensioning of the length of the pause.
[0021] Further, radio bursts of at least one radio burst cluster may be within the coherence time, preferably radio bursts of at least two radio burst clusters on the uplink may be within the coherence time, and / or fewer radio burst clusters may be within the coherence time in a first or earlier part of a data packet transmission than in a second or later part of the transmission.
[0022] Preferably, at least one frequency and / or time readjustment, preferably multiple consecutively occurring frequency and / or time readjustments, may be performed upon reception of a radio burst. In particular, this enables the following adaptive measures to be taken to reduce the load on the energy buffer: a lower number of symbols per radio burst (FB) before the first frequency and / or time realignment than thereafter, e.g., 24 symbols instead of 36 symbols; and / or the length of each pause (ΔT_add) is shorter before the first frequency and / or time readjustment than afterwards, and / or a higher average energy consumption per unit time before the first frequency and / or time readjustment than after it; a higher average current is drawn from the energy buffer (7) before the first frequency and / or time readjustment than afterwards; the length of the time transmission interval (T_RB(s)) is shorter before the first frequency and / or time readjustment than after the first frequency and / or time readjustment; and / or Before the first frequency and / or time realignment there is a lower number of radio bursts (FB) per radio burst cluster (CL1, CL+x) than afterwards.
[0023] Thus, the frequency and / or time readjustment can result in an extension of the pauses (ΔT_add) and / or block pauses (ΔT_dn) and / or of the time transmission interval (T_RB(s)). Thus, the length of the pauses of the core frame can be dimensioned taking into account the accuracy of the crystal of the node and / or the length of the pauses of the extended frame can be dimensioned taking into account the accuracy of the crystal of the base station. For example, in the uplink and / or downlink, radio bursts or pauses of the core frame located therein can first be separated based on a coherence time that depends on the crystal used for time measurement in the node. For the radio bursts or blocks of the extended frame containing the radio bursts, a frequency and / or time readjustment, i.e. a resynchronization, can be performed, and then the pauses between clusters of the extended frame, or additional pauses, can be increased taking into account the coherence time. As a result, the core frame can be sent out unchanged or at least with shorter pauses, but larger pauses can be provided in the extended frame due to the increase in the coherence time within the extended frame.
[0024] It has been shown to be particularly advantageous for the energy buffer if radio burst clusters having nine radio bursts each are formed in the downlink and / or radio burst clusters having six radio bursts each are formed in the uplink.
[0025] Preferably, within the coherence time, there are at least 9 radio burst clusters in the downlink and at least 12 radio burst clusters in the uplink.
[0026] According to a further embodiment of the invention, which is also claimed as a subclaim, in order to reduce the energy buffer or to avoid not reaching the minimum operating voltage, The length of the radio burst is reduced by increasing the data rate compared to a data rate of 2,380,371 sym / s, and / or Preferably, in the downlink, the length of the radio burst, preferably the length of the extended frame, is limited to a value smaller than the maximum possible length of a radio burst of the wireless network, and / or the size of the data packets is limited and / or only radio bursts having a predefined maximum length are transmitted and / or allowed for further processing after reception; and / or The transmission power is reduced to a value below 10 dBm, and / or Only a subset of radio bursts from the total number of radio bursts of a data packet are sent out and / or allowed for further processing after reception.
[0027] Limiting the length of each radio burst means that only radio bursts that match a predefined limit are sent out. In particular, the length of each radio burst can be limited such that a maximum "on-air time" is specified. Depending on the payload length, different radio burst lengths are obtained. The relationship is not linear but follows a sawtooth function. The longer the payload length, the shorter the radio burst length may be. Here, for example, additional dummy bytes are added, so that a larger payload length is obtained, which has a smaller radio burst length.
[0028] Another way to use a small energy buffer is to limit the payload, i.e. send out smaller data packets essentially. For example, with a very small energy buffer, two packets of 50 bytes each can be sent instead of a 100 byte packet. This reduces the number of radio bursts per packet. The second packet is not sent until later, for example 30 minutes later.
[0029] If only radio bursts with a predefined maximum length are sent out and / or allowed for further processing after reception, this ensures that the operating voltage remains permanently above the threshold, which compensates for a slightly lower fault tolerance, or some loss of sensitivity.
[0030] To reduce the load on the energy buffer, the radio bursts of the core frame may be transmitted at shorter time intervals than the radio bursts of the extended frame.
[0031] Furthermore, preferably on the uplink, the number of symbols per radio burst of a core frame is limited to a number less than the maximum possible number, effectively preferably less than 36 symbols / radio burst.
[0032] According to the method of the invention, an operating voltage threshold for the energy buffer (e.g. 2.8-3.0 V) can be specified, which serves as a control variable for the selection of the method mode for mitigating the energy buffer according to the invention. Preferably, the method mode can be selected from several possible method modes.
[0033] Furthermore, the method mode may be pre-calculated. An approval decision may then be made in the base station as to the method mode in which operation should take place depending on the operating voltage threshold.
[0034] According to an exemplary embodiment of the invention, at least two different modes of emitting and / or receiving radio bursts, having different impacts on the discharge of the energy buffer, may be provided for selection. Preferably, the node signals which of the at least two modes is or is not suitable for it based on its energy buffer. An approval may then be decided at the base station or at the headend, e.g. as to whether the method mode as described in the preceding claims is enabled or not.
[0035] Thus, multiple nodes with different energy buffers may be provided in a wireless network.
[0036] Preferably, electrolytic capacitors are used as energy buffers, as such energy buffers are 5-10 times cheaper than hybrid layer capacitors (HLC).
[0037] The invention further relates to a node according to the preamble of claim 23, characterized in that the microprocessor and / or the transceiver of the node are operated according to the method according to the preceding claims.
[0038] Examples of advantageous embodiments of the invention will now be explained in more detail with reference to the figures of the drawings. [Brief description of the drawings]
[0039] [Figure 1] 1 is a highly simplified schematic diagram of a wireless network, preferably an SRD wireless network, for applying the method according to the invention; [Diagram 2] FIG. 2 is a highly simplified schematic diagram of an example of functional elements that a node of a wireless network comprises; [Diagram 3] FIG. 3 shows an exemplary wiring configuration of the energy buffer of the node according to FIG. 2. [Figure 4] 1 is an exemplary graph of a drawn current and operating voltage curve of a node's energy buffer over time during emission of a data packet on the uplink and downlink. [Figure 5a] 1 is an exemplary diagram of division of a radio burst block into individual clusters and separation of the clusters by pauses ΔT_add in the uplink; [Figure 5b] FIG. 13 is an exemplary diagram of the formation of clusters with intervening pauses ΔT_add in the downlink. [Figure 6] 13 is an exemplary graph of both the drawn current and operating voltage curves of a node's energy buffer over time during the emission of data packets on the uplink and downlink, thereby forming individual radio burst clusters and separating the clusters by pauses ΔT_add. [Figure 7]FIG. 7 is an enlarged view of a portion of the operating voltage curve of the graph in FIG. 6 for the uplink. [Figure 8] 1A-1D are highly simplified schematic diagrams of examples of different cluster arrangements according to the present invention; [Figure 9] FIG. 13 is an illustration of increasing the data rate as a measure to reduce the load on the energy buffer. [Figure 10] FIG. 2 is a diagram of the "on-air time" of a radio burst as a function of the payload or length of the radio burst. [Figure 11] FIG. 13 illustrates splitting a radio burst into two separate radio bursts as a measure to reduce the load on the energy buffer. [Figure 12] FIG. 13 illustrates an example of radio bursts of a particular length that are allowed in an extended frame as a measure to reduce the load on the energy buffer. [Figure 13] FIG. 1 illustrates an example of emitting radio bursts as a measure to reduce the load on an energy buffer. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] Fig. 1 shows a wireless network 100, preferably of the type defined in the ETSI TS 103357 V1.1.1 (2018-06) standard. It comprises a plurality of individual energy-independent operating nodes 1a-1n and a base station 10 (sometimes called data collector). The nodes 1a-1n are in particular sensor devices, actuators or a combination thereof for use in the so-called IoT. In these, data from the individual nodes 1a-1n are transmitted by radio transmission 9 to the base station 10 (uplink) and / or data are transmitted by radio transmission 9 from the base station 10 to the individual nodes 1a-1n (downlink). The individual nodes 1a-1n are within the transmission and reception range of the respective base station 10.
[0041] Node 1 may be, for example, a water meter, a gas meter, an electricity meter, or an energy meter.
[0042] The data of the nodes 1a-1n received from the base station 10 can then be transmitted to the headend 20 or to a data center via suitable data transmission means 11. The data transmission means 11 can be, for example, a cellular or Internet connection or a combination of these. The data is transmitted by telegraph division in narrowband, preferably in ultra-narrowband, particularly preferably within the context of so-called telegraph division (TS-UMB family). The uplink usually concerns mainly the transmission of user data generated in the individual nodes 1a-1n and / or operational data of the individual nodes. The data provided by the headend 20 to the base station 10 via the data transmission means 11 and transmitted onward by radio transmission 9 in the downlink to the nodes 1a-1n are mainly configuration data, data for the operating systems of the individual nodes, software updates, etc.
[0043] Fig. 2 shows an exemplary structure of a node 1a for use in the method according to the invention. The node 1a comprises a microprocessor 2, a transceiver 3 and an antenna 4 for transmitting or receiving radio signals of a radio transmission 9. Furthermore, the node 1a comprises a memory 5, a battery 6 and an energy buffer 7. The battery 6 is preferably a so-called long-life battery, i.e. a non-rechargeable battery, which supplies energy to the node 1a for the entire usage cycle of the node 1a until the battery needs to be replaced. Such a long-life battery has a life of more than 10 years, assuming a normal power consumption of the node 1a. Power to the microprocessor 2 or the transceiver 3 or the memory 5 is supplied via an energy buffer 7 upstream of the battery 6, which is discharged when an energy demand occurs and then recharged by the battery. The above-mentioned components of the node 1a, such as the microprocessor 2, the transceiver 3, the antenna 4 and / or the memory 5, may also be provided in a modular component.
[0044] Reference 2a designates a quartz crystal provided as a time measurement device, i.e. for acting as a time reference and for generating a carrier signal. The base station is also equipped with a quartz crystal (not shown) which generates the clock for the carrier signal for the carrier frequency of the radio signal sent by the base station 10 and is responsible for the time measurements carried out therein. The precision of the two crystals is different: the crystal of the base station 10 has a precision of about 2 ppm, while the crystal 2a only has a precision of about 20 ppm.
[0045] As can be seen from figure 3, the battery 6 has a certain internal resistance 8. The microprocessor 2 and the transceiver 3 form "consumers" of the energy stored in the energy buffer 7. When the energy stored in the energy buffer 7 is consumed by the microprocessor 2 or the transceiver 3, for example because a data packet (telegram) is sent or received, the energy buffer 7 is discharged for a certain length of time until it is recharged by the battery 6. This causes a voltage drop in the energy buffer 7. The voltage drop depends on the energy required by the consumer. The voltage drop and recharge of the energy buffer 7 is illustrated below using an example.
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[0046] The electronics of node 1a require a stable voltage of the energy buffer 7 in order for it to function. A stable voltage means a minimum voltage or voltage threshold that must not be reached during operation. For example, the minimum voltage for a conventional node is in the range of 2.7 to 3.0 V.
[0047] For better understanding, the top left diagram in Fig. 4 shows an example of current distribution for the transmission of a telegram in the uplink in the conventional telegram division method, and the right side shows the current distribution in the downlink for the reception of all sub-data packets by a node in the conventional telegram division method. The telegram division method means that a data packet is divided into individual sub-data packets, which are each sent out consecutively as a radio burst, received by a receiver, and recombined again to form information in a data packet. The time interval T_RB for the continuous continuous transmission of sub-data packets is about 150 ms in the uplink and about 220 ms in the downlink on average.
[0048] According to the invention, the sub-data packets can be sent over a single frequency channel or alternatively over a number of different frequency channels in a so-called frequency hopping procedure.
[0049] As can be seen from Fig. 4, in the conventional method, the energy buffer 7 is strongly discharged by sending a data packet on the uplink until it is charged again above the operating voltage threshold V_min at about 2.9V, during a rest period of 0.37 seconds due to charging by the battery 6. When a data packet is received by the node's receiver on the downlink, the energy buffer 7 is again strongly discharged. It is then recharged, which is not shown in the upper diagram of Fig. 4. It can be seen that the energy buffer 7 is below the operating voltage threshold V_min line for a significant period of time during the uplink and downlink. Conventionally, so-called hybrid layer capacitors (HLC) are commonly used to prevent over-discharge. HLC is expensive.
[0050] 5a and 5b show a section of the so-called telegram segmentation procedure, in which a data packet DP intended for sending in the uplink or for receiving in the downlink by the respective node 1a to 1n is divided, i.e. "segmented", into individual sub-data packets C1 to C1+m, E1 to E1+n according to ETSI TS 103357 V1.1.1 (2018-06). For the transmission of the data packet DP, it may first be segmented into a so-called core frame CF and an extended frame EF, where the extended frame EF typically contains at least essentially user data and the core frame CF contains at least essentially control information. For the transmission, the data of the extended frame EF is segmented into individual sub-data packets E1 to E1+n. Similarly, on the uplink, the data of the core frame CF is also segmented into sub-data packets C1 to C1+m, as shown in Fig. 5a and Fig. 5b, respectively.
[0051] According to ETSI TS 103357 V1.1.1 (2018-06), the individual sub-data packets E1 to E1+n and the corresponding radio bursts FB are transmitted after being combined in a number of blocks B1, B2, ..., as shown in Fig. 5b. Adjacent radio bursts generally have a time interval T_RB for each of the two radio bursts FB of the extended frame, as shown in the examples of Fig. 5a and 5b. The pause between the core frame and the extended frame is specified as ΔT_si in ETSI TS 103357 V1.1.1 (2018-06). A block B in the downlink in a conventional wireless system consists of, for example, 18 radio bursts or sub-data packets E1 to E18. Conventionally, a block pause ΔT_dn is provided between each block. In the ETSI TS 103357 V1.1.1 (2018-06) wireless standard, this block pause can be up to 7,168 symbols based on a symbol rate of 2,380,371 sym / s, which corresponds to a time value of 3.011 seconds.
[0052] A block B in the uplink conventionally consists of, for example, 24 radio bursts or sub-data packets E1 to E24.
[0053] In order not to fall below the operating voltage threshold V_min of the energy buffer 7, according to one aspect of the invention, on the one hand, a pause (ΔT_add) is provided between two adjacent radio bursts (FB) of a frame on the uplink and / or downlink, which is longer than 7,168 symbols based on a symbol rate of 2380.371 sym / s.
[0054] On the other hand, alternatively or additionally, it is provided to set the time transmission interval (T_RB(s)) on the uplink and / or downlink to be greater than 655 symbols based on a symbol rate of 2,380,371 sym / sec.
[0055] Alternatively or additionally, it is provided to divide the radio bursts FB of the core frame CF and the extended frame EF into clusters CL1 and CL2 on the uplink, as shown by way of example in Fig. 5a, with pauses ΔT_add between each of the clusters. Furthermore, according to Fig. 5b, corresponding clusters CL with pauses ΔT_add may also be formed on the downlink. On the downlink, blocks B1, B2, ... of the extended frame may be divided and separated by pauses ΔT_add. Clusters CL of different blocks may also be separated from each other by pauses ΔT_add. In this case, the pauses ΔT_add are greater than the block pauses ΔT_dn. This is shown in Fig. 5b. However, alternatively, the block pauses ΔT_dn may also be kept. Preferably, in order to relieve the energy buffer for generating the number of radio bursts in the respective radio burst cluster, the number of radio bursts per block predefined according to ETSI TS 103357 V1.1.1 (2018-06) may be divided into integer numbers. For example, in the case of an uplink according to FIG. 5a, the 24 radio bursts FB of a block B may be divided into, for example, four clusters CL1 to CL4 each having 6 radio bursts and sent offset with respect to each other by an additional pause ΔT_add.
[0056] Similarly, on the downlink according to FIG. 5b, a block may be divided into two clusters with nine radio bursts each and received from nodes spaced apart from each other by an additional pause ΔT_add.
[0057] In 5b, the core frame is transmitted without pauses and only the blocks of the extension frame are divided into clusters. Alternatively, however, the core frame may also be divided into clusters with additional pauses ΔT_add, i.e., the clusters may be sent or received with intervening pauses ΔT_add to reduce the energy buffer.
[0058] The length of the pause ΔT_add may remain constant or variable in the uplink and / or downlink. Thus, the length of the pause ΔT_add in a core frame may be shorter than in an extended frame.
[0059] The upper diagram of Fig. 6 shows, by way of example, the current drawn from the energy buffer 7 both on the uplink and on the subsequent downlink. Each dash in this diagram corresponds to a cluster CL that includes several radio bursts. The time between two dashes corresponds to a respective pause ΔT_add. In the example of Fig. 6, the pause is ΔT_add 12 seconds.
[0060] The lower diagram in Fig. 6 shows the change in the operating voltage of the energy buffer 7 during each discharge caused by a transmission or reception at node 1. It can be seen that the clustering and the respective pause ΔT_add do not cause the operating voltage of the energy buffer 7 to fall below the operating voltage threshold V_min for both the uplink and the downlink, so that the operating voltage of the energy buffer remains at the required level.
[0061] FIG. 7 shows, for example, a scaled down version of the discharge curve of FIG. 6 on a downlink with six clusters each containing nine radio bursts.
[0062] For dimensioning of the additional pause ΔT_add, i.e. the time interval between the respective clusters CL, the so-called coherence time must be observed. The coherence time is the time during which a radio burst FB of a transmission can still be used by the receiver without the need to readjust the frequency or time. The coherence time is defined by specifying the maximum time error in the form of a fraction of the symbol duration (for example 0.25). The coherence time depends on the frequency accuracy of the frequency crystal and can be expressed as follows:
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[0063] One possibility according to the invention is to choose the additional pause ΔT_add according to the top diagram of figure 8, so that the coherence time is maintained. In that case, no frequency or time readjustment is required in the receiver.
[0064] Alternatively, the pause ΔT_add according to the middle diagram of Fig. 8 can be chosen to be outside the coherence time, in which case the frequency and / or time must be readjusted.
[0065] Alternatively, there is also a mixed option, as shown in the lower diagram of Figure 8. This means that a pause ΔT_add between two clusters CL is within the coherence time and a second pause between two clusters CL is outside the coherence time. This option is particularly interesting for the uplink.
[0066] In the uplink, due to the greater inaccuracy of the crystal 2a used there, the coherence time becomes:
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[0067] For the downlink, this allows a factor of 2.5 improvement (increase in coherence time) to be achieved, and for the uplink, another factor of 10. On the uplink, the carrier frequency is known after 12 radio bursts have been received. This allows the accuracy to be reduced to 20 ppm, as explained above. This also allows the number of radio bursts (FB) per radio burst cluster to be reduced. For example, instead of 24 radio bursts, only 12 radio bursts may be sufficient in the uplink. Preferably, in the downlink, a radio burst cluster (CL1, CL+x) comprises 9 radio bursts and in the uplink 12 radio bursts.
[0068] Furthermore, after the initial frequency and / or time adjustment, the number of symbols per radio burst (FB) may be reduced, for example, to 24 instead of 36 symbols per burst.
[0069] For a coherence time of 52.53 seconds, in the uplink, a pause ΔT_add of, for example, 12 seconds may be provided between each of, for example, four clusters CL1 to CL4, each including six radio bursts, resulting in a total time for the uplink of 36 seconds, which is within the coherence time of 52.53 seconds.
[0070] Due to the initial frequency and / or time readjustment, the length of the time transmission interval (T_RB(s)) may also be extended compared to its previous value.
[0071] Thus, by performing at least one frequency and / or time readjustment, the average energy consumption per unit time and the average current drawn from the energy buffer for a radio burst following the frequency and / or time readjustment is reduced, thereby effectively protecting the energy buffer.
[0072] To avoid over-discharging the energy buffer 7, the data rate may also be increased. For example, the data rate may be increased compared to a data rate of 2,380,371 sym / s. This results in shorter data packets or telegrams and less energy required from the energy buffer 7. For example, increasing the data rate by a factor of two results in a radio burst FB of a data packet being twice as short. This may help to alleviate the energy buffer by itself. Furthermore, the increase in the data rate may also be used in combination with providing a pause ΔT_add. Thus, the two measures may be advantageously combined. Increasing the data rate means some loss of sensitivity, but nevertheless allows the use of cheaper components in the nodes. Thus, for example, the head end 20 may assign different data rates to the individual nodes. The increase in the data rate combined with the use of a pause ΔT_add is shown diagrammatically in FIG. 9.
[0073] The radio bursts FB on the downlink have different lengths depending on the payload. Another way to alleviate the energy buffer 7 is to allow radio bursts FB with a certain length, so that only radio bursts FB not exceeding this size are sent and received by the node.
[0074] The graph of FIG. 10 shows the relationship between the length of the payload, i.e. the radio burst FB, as a function of the "on-air time" of the radio burst. As the length of the radio burst FB increases, its "on-air time" also increases. In the case of a larger continuous payload, i.e. in one radio burst, more energy is consumed, so that the requirements for the operating voltage of the energy buffer 7 can no longer be met. The measure taken by the invention is therefore to split the payload into parts and to send and / or receive said parts of the payload in a split form, by several radio bursts, in order to meet the voltage requirements. A corresponding subdivision of the payload is shown diagrammatically in FIG. 11. Each radio burst FB1, FB2 contains one part of the maximum payload PL. This measure can be used alone to relieve the energy buffer 7 or in conjunction with the measures mentioned above (pause ΔT_add and / or increase of the data rate).
[0075] Instead of splitting the payload or data packets, radio bursts that exceed a certain length (L_max) may for example not be allowed to be received and therefore not be processed. The relationship between payload and radio burst length for the sawtooth curve of Figure 10 is shown in Figure 12 for a range between 20 and 30 bytes.
[0076] Another measure to be applied alone or in conjunction with other solution ideas to mitigate the energy buffer 7 consists of omitting radio bursts of the transmission and / or reception chains of radio bursts of data packets. For example, instead of sending or receiving 9 radio bursts, this could be only 8 radio bursts, as is evident from FIG. 13. This also allows the operating voltage of the energy buffer 7 to be kept above the minimum operating voltage V_min. In exchange for that, a slightly lower fault tolerance and possibly a small loss of sensitivity must be accepted. This measure can be used alone or in conjunction with the measures mentioned above (pause ΔT_add and / or data rate increase and / or radio burst splitting) to mitigate the energy buffer 7.
[0077] Another measure to alleviate the energy buffer 7 is to limit, preferably in the uplink, the number of symbols per radio burst FB of a core frame CF to a number smaller than the maximum possible number. According to ETSI TS 103357 V1.1.1 (2018-06), a radio burst of a core frame CF on the uplink consists of 36 symbols (bits). For example, it is possible to send only 26 symbols (bits) per radio burst FB in a core frame CF. This also alleviates the load on the energy buffer 7 by preventing its discharge below the operating voltage threshold V_min. This measure can be used alone or in combination with one or all of the above-mentioned measures.
[0078] As a further measure to protect the energy buffer, the transmission power may be reduced to a value below 10 dBm. This measure may also be used alone or in combination with one or all of the measures mentioned above.
[0079] According to the invention, a specific value for the operating voltage threshold V_min for the energy buffer 7 may be predefined, which may preferably be provided at the same time as a control parameter or control variable for selecting a method mode from a plurality of selectable method modes. Such a method mode may be one of the above measures of providing a pause ΔT_add, increasing the data rate, allowing radio bursts of a certain length, omission of radio bursts, radio bursts with a lower number of symbols, or a combination thereof. Depending on the particular product, different transmit and / or receive currents may be used, batteries may have different internal resistances, sensors may have different voltage requirements, and the fact that a given operating mode that may be selected as needed may provide considerable advantages in use.
[0080] Likewise, according to the invention, the voltage can be monitored as a controlled variable and, if a certain voltage is present, a certain method mode can be selected in which the energy buffer 7 is protected by the measures described.
[0081] Another aspect of the invention involves providing at least two different modes of sending and / or receiving radio bursts or radio burst clusters, which have different effects on the discharge of the energy buffer 7. In this case, the node 1 can signal to the base station 10 which mode is appropriate based on its energy buffer 7. Then, by selecting the appropriate mode, communication in the wireless network can be performed. Similarly, calculations can be performed in advance to determine which method mode is appropriate for which node. Depending on the result, only the method mode that reliably precludes the discharge of the energy buffer 7 below the voltage threshold V_min can be enabled. This is advantageous when nodes are operated with different energy buffers in a wireless network (radio cell).
[0082] Thus, with the present invention, due to the possibility of using less expensive energy buffers, significant cost reductions in the manufacture of nodes for SRD wireless networks can be achieved.It is expressly pointed out that even subcombinations of features in this specification, even if not explicitly mentioned, are considered essential to the present invention. [Explanation of symbols]
[0083] 1a~1n nodes 2 Microprocessor 2a Quartz Crystal (Time) 2b Quartz crystal (carrier frequency) 3 Transceiver 4 Antennas 5. Memory 6 Battery 7 Energy Buffer 8 Internal Resistance 9 Radio Transmission 10 base station 11 Data transmission means 20 Headend 100 Short-range wireless network FB Radio Burst CF Core Frame EF Extended Frame C Sub Data Packet E sub data packet DP Data Packet Block B CL Cluster PL Payload
Claims
1. A method for operating a node (1), preferably an end node, in a wireless network (100) comprising at least one node (1) and at least one base station (10), comprising: said node (1) comprising a transmitter and / or receiver, preferably a transceiver (5), for transmitting radio messages in the form of data packets (DP) on an uplink and / or receiving them on a downlink, a battery (6) and an energy buffer (7), each data packet (DP) on the uplink and / or downlink is divided into a plurality of individual sub-data packets, which are preferably sub-data packets of different frames of the data packet (DP), in particular sub-data packets (C1 to C1+m or E1 to E1+n) of a Core Frame (CF) and / or an Extended Frame (EF) of the data packet (DP), each sub-data packet being sent and / or received consecutively in a time transmission interval (T_RB(s)) in the form of a radio burst (FB), preferably in a narrowband or very narrowband, preferably at a different frequency; at least two, preferably a plurality of pauses (ΔT_add) are provided, each said pause (ΔT_add) being provided between two adjacent radio bursts (FB), in each case longer than 7,168 symbols based on a symbol rate of 2,380,371 sym / s; and / or radio bursts (FB) are combined into radio burst clusters (CL1, CL+x), and the radio bursts (FB) in the radio burst clusters (CL1, CL+x) are each transmitted and / or received consecutively in the time transmission interval (T_RB(s)), and at least one radio burst cluster (CL1, CL+x) on the uplink comprises less than 24 radio bursts (FB), and / or at least two radio burst clusters (CL1, CL+x) on the downlink comprise less than 18 radio bursts (FB); and / or the time transmission interval (T_RB(s)) is greater than 655 symbols based on a symbol rate of 2,380,371 sym / sec; method.
2. 2. The method of claim 1, wherein each said pause (ΔT_add) is provided between two adjacent radio bursts (FB) of a frame, preferably of the core frame (CF) and / or the extended frame (EF).
3. 2. The method of claim 1, wherein the pause (ΔT_add) is provided between two adjacent radio bursts (FB) of a frame, each belonging to a different radio burst cluster (CL1, CL+x).
4. 2. The method of claim 1, wherein the radio burst clusters (CL1, CL+x) each comprise the same number of radio bursts (FB).
5. 2. The method of claim 1, wherein a number of radio bursts (FB) per block predefined in ETSI TS 103357 V1.1.1 (2018-06) is divided into integers to generate the number of radio bursts (FB) in each of the radio burst clusters (CL1, CL+x).
6. 2. The method of claim 1, wherein, preferably on the uplink, the pause (ΔT_add) is not provided in a first part of the data packet (DP) or a frame of the data packet (DP), and the pause (ΔT_add) is provided in a second part of the data packet (DP) or a frame of the data packet (DP), or the pause (ΔT_add) in the first part of the data packet (DP) or the frame of the data packet (DP) has a shorter length than in the second part of the data packet (DP) or the frame of the data packet (DP).
7. The Core Frame (CF) does not include a pause (ΔT_add) and the Extended Frame (EF) includes the pause (ΔT_add), or The core frame (CF) and the extension frame (EF) each include a pause (ΔT_add), and the pause (ΔT_add) of the core frame is smaller than the pause (ΔT_add) of the extension frame (EF); The method of claim 6.
8. 2. The method of claim 1, wherein a position or distribution of each pause (ΔT_add) within the data packet (DP) or the frame, and / or a length of each pause (ΔT_add), and / or a number of radio bursts (FB) per radio burst cluster (CL1, CL+x), and / or a number of symbols per radio burst (FB) are specified such that a coherence time is maintained.
9. 2. The method of claim 1, wherein the radio bursts (FB) of at least one radio burst cluster (CL1, CL+x) are within a coherence time, preferably the radio bursts (FB) of at least two radio burst clusters (CL1, CL+x) on the uplink are within the coherence time, and / or fewer radio burst clusters (CL1, CL+x) are within the coherence time in a first part of a transmission of the data packet (DP) than in a second part of the transmission.
10. 2. The method of claim 1, wherein the accuracy of the crystal oscillator (2a) of the node (1) and / or the crystal oscillator of the base station (10) is included in determining the length of the pause (ΔT_add).
11. 2. The method of claim 1, wherein the radio bursts (FB) of at least one radio burst cluster (CL1, CL+x) are within a coherence time, preferably the radio bursts (FB) of at least two radio burst clusters (CL1, CL+x) on the uplink are within the coherence time, and / or fewer radio burst clusters (CL1, CL+x) are within the coherence time in a first part of a transmission of the data packet (DP) than in a second part of the transmission.
12. A frequency and / or time readjustment is carried out, in particular a lower number of symbols per radio burst (FB) before the first frequency and / or time readjustment than afterwards; and / or the duration of each pause (ΔT_add) is shorter before the first frequency and / or time readjustment than afterwards; and / or a higher average energy consumption per unit time before said first frequency and / or time readjustment than after said first frequency and / or time readjustment; and / or a higher average current is drawn from the energy buffer (7) before the first frequency and / or time readjustment than afterwards; and / or the time transmission interval (T_RB(s)) has a shorter length before the first frequency and / or time readjustment than after the first frequency and / or time readjustment; and / or a lower number of radio bursts per radio burst cluster (CL1, CL+x) before said first frequency and / or time readjustment than after said first frequency and / or time readjustment; The method of claim 1.
13. 2. The method of claim 1, wherein the pauses (ΔT_add) between the radio burst clusters (CL1, CL+x) of the extended frame (EF) are greater than the pauses (ΔT_add) between the radio burst clusters (CL1, CL+x) of the core frame (CF).
14. radio burst clusters (CL1, CL+x) each having nine radio bursts are formed on the downlink; and / or Radio burst clusters (CL1, CL+x), each having six radio bursts, are formed on the uplink; The method of claim 1.
15. 2. The method of claim 1, wherein at least nine radio burst clusters (CL1, CL+x) in the downlink and at least twelve radio burst clusters (CL1, CL+x) in the uplink are within a coherence time.
16. A method for operating a node (1), preferably an end node, in a wireless network (100) comprising at least one node (1) and at least one base station (10), comprising: said node (1) comprising a transmitter and / or receiver, preferably a transceiver (5), for transmitting radio messages in the form of data packets (DP) on an uplink and / or receiving them on a downlink, a battery (6) and an energy buffer (7), each data packet (DP) on the uplink and / or downlink is divided into a plurality of individual sub-data packets, preferably sub-data packets of different frames of the data packet (DP), in particular sub-data packets (C1 to C1+m or E1 to E1+n) of a core frame (CF) and / or an extended frame (EF) of the data packet (DP), each sub-data packet being sent and / or received consecutively in a time transmission interval (T_RB(s)) in the form of a radio burst (FB), preferably in a narrowband or ultra narrowband, preferably at different frequencies, in order to reduce the load on the energy buffer (7); The length of the radio burst (FB) is reduced by increasing the data rate compared to a data rate of 2,380,371 sym / s, and / or Preferably, in the case of the downlink, the length of the radio burst (FB), preferably of the extended frame (EF), is limited to a value (VL) that is smaller than the maximum possible length (ML) of the radio burst (FB) of the wireless network (100), and / or the length of the payload is limited to a value less than the maximum possible length of said payload; and / or The transmission power is reduced to a value below 10 dBm, and / or Only radio bursts (FB) with a predefined maximum length are transmitted and / or allowed for further processing after reception, and / or only a subset of radio bursts (FB) from the total number of radio bursts (FB) of said data packet (DP) are sent and / or allowed for further processing after reception, method.
17. The length of each said radio burst (FB) is limited to specify a maximum "on-air time" by adding additional dummy bytes, or The maximum length of the payload PL is limited so that only a part of the data packet (DP) is transmitted initially.
17. The method of claim 16.
18. 17. The method of claim 16, wherein the radio bursts (FB) of the core frame (CF) are transmitted at shorter time intervals than the radio bursts (FB) of the extended frame (EF).
19. 17. The method of claim 16, wherein, preferably on the uplink, the number of symbols per radio burst (FB) of the core frame (CF) is limited to a number less than the maximum possible number, preferably less than 36 symbols / radio burst.
20. 17. The method according to claim 16, wherein an operating voltage threshold (V_min) is specified, which is used as a control variable, in particular for the selection of the method mode according to any of claims 1 to 15.
21. 17. The method of claim 16, wherein a plurality of nodes (1) with different energy buffers (7) are provided in the wireless network (100).
22. 17. The method of claim 16, wherein at least two different modes of emitting and / or receiving radio bursts, having different effects on the discharge of the energy buffer (7), are predefined for selection, and the node (1) preferably signals, based on its energy buffer (7), which of the at least two modes is / is not suitable for it.
23. 17. The method according to claim 16, wherein an electrolytic energy buffer or an energy buffer with a capacitance of up to 25,000 μF is used as the energy buffer (8).
24. A node (1), preferably an end node, for a wireless network (100) for communication with a base station (10) of said wireless network (100) on an uplink and / or a downlink, a microprocessor (2); a transmitter and / or receiver, preferably a transceiver (5), for transmitting radio messages in the form of data packets (DP) on the uplink and / or receiving them on the downlink; a battery (6); Energy buffer (7) and wherein the microprocessor (2) and / or the transmitter and / or the receiver, preferably the transceiver (5), are operated according to the method of any of claims 1 to 19 or any of claims 21 to 23. Node (1).