Method for coordinating participants in a sensor network

Abstract

An embodiment of the present invention provides a participant of a communication system, wherein: the communication system performs wireless communication in a frequency band used by multiple communication systems, wherein the participant is designed to send data in an uncoordinated process relative to other participants and / or base stations of the communication system; and wherein the participant is designed to receive synchronization data packets sent by point-to-multipoint data of a base station of the communication system. The synchronization data packets are sent in a predetermined frequency range of the frequency band or in a frequency band range known to the participant, and the participant is designed to receive user data packets sent by the point-to-multipoint data with reference to the time and / or frequency of the synchronization data packets based on the synchronization data packets.

Description

Technical Field

[0001] Embodiments of the invention relate to wireless communication systems with multiple non-coordinated transmitting participants, and in particular to transmitting multicast messages (point-to-multipoint messages) in such communication systems.Some embodiments relate to a method for coordinating participants in a sensor network. Background Art

[0002] In a typical radio network (or wireless communication system), such as GSM (Global System for Mobile Communications), there is a coordination instance whereby radio resources are provided to participants of the radio network as needed, which resources are dedicated for use by the respective participants.

[0003] This ensures that each participant can transmit its data in the radio resources reserved specifically for it. This avoids interference between participants of the radio network, thereby maximizing throughput.

[0004] In such radio networks, the coordination of the participants regarding radio resources is usually carried out via so-called beacons, which the network participants listen to. With the signaling of the radio resources in these beacons, all participants are required to receive and evaluate them in order to be able to subsequently receive or send data. As a result, participants who rarely access the channel have a very high current consumption.

[0005] In contrast, another approach is an uncoordinated radio network, in which participants transmit their data to the receiver in a contention-based manner. Therefore, it is not necessary to continuously receive beacons that indicate when and which participant is allowed to transmit on which frequency. This reduces the current consumption of the participants, as they only need to be activated when needed.

[0006] However, a disadvantage of this approach is the possibility of interference between the participants of the radio network. However, this disadvantage can be reduced by using “Telegram Split Multiple Access” (TSMA) [4], which allows to obtain a throughput similar to that of a coordinated system.

[0007] In Telegram Splitting Multiple Access (TSMA), the transmission of a message (data packet) is divided into multiple short sub-packets (bursts) with transmission-free intervals of varying lengths between each sub-packet. In this case, the sub-packets are pseudo-randomly distributed over time and available frequency channels, such as Figure 1 as shown in .

[0008] In detail, Figure 1 The schematic diagram shows the occupation of the frequency band of a communication system based on TSMA when transmitting a data packet divided into a plurality of sub-data packets 10, wherein the plurality of sub-data packets are distributed in time and frequency. Figure 1 In , the ordinate describes the frequency (frequency channel) and the abscissa describes the time. In other words, Figure 1 The principle of data transmission according to the TSMA method is shown.

[0009] [1] shows that the TSMA method can achieve a higher data transmission capacity than transmitting data packets in consecutive blocks, i.e. without the need for subdivision into sub-packets 10. In order to achieve the largest possible system capacity, as many different time and / or frequency hopping patterns as possible should be used [3]. The total number of time and / or frequency hopping patterns should be limited and should be derived from a list of pre-known time and / or frequency hopping patterns.

[0010] Contention-based access to the channel at random points in time leads to asynchronous transmission, e.g. Figure 2 A communication system without TSMA is exemplarily shown in FIG.

[0011] Specifically, Figure 2 The frequency band occupation of a contention-based communication system in the transmission of a plurality of uplink messages 12 and a plurality of downlink messages 14 is schematically shown. Figure 2 In the example, the horizontal axis describes the frequency and the vertical axis describes the time. In other words, Figure 2 A schematic diagram of transmission channels in an uncoordinated communication system is shown.

[0012] In an uncoordinated communication system, there are usually multiple participants (e.g., end points) communicating with a base station. In this case, the message transmission from the participants to the base station is the uplink, while the downlink occurs in the opposite direction.

[0013] For energy efficiency reasons, participants usually turn on their send / receive modules only when they want to send a message. Figure 2 One of the downlink messages 14 shown in is not possible.

[0014] To solve this problem, [4] defined that a participant waits for a certain defined time after transmitting an uplink message and then opens a reception window for downlink messages. Therefore, the base station can only send a downlink message to this participant at a certain point in time.

[0015] Typically, the downlink to participants employing uncoordinated transmission is used for messages to be transmitted to multiple participants, such as software updates or time synchronization commands.

[0016] Due to the asynchronous network approach (contention-based access) in [4], downlink messages must be shared with each participant individually. This is a problem especially in large radio networks with many participants, since it takes a long time until all participants get the data for a large number of participants.

[0017] In a coordinated communication system, a point-to-multipoint message (multicast message) can be signaled from a base station to participants in a beacon. All participants that receive the beacon can then also receive the corresponding resources of the multicast message. Summary of the invention

[0018] The invention is therefore based on the object of enabling the transmission of point-to-multipoint messages in a communication system having a plurality of uncoordinated transmission participants.

[0019] This object is solved by the independent patent claims.

[0020] Advantageous further developments can be found in the dependent patent claims.

[0021] An embodiment provides participants of a communication system, [wherein the communication system performs wireless communications in a frequency band [e.g., an ISM band] used by multiple [e.g., mutually non-coordinated] communication systems], wherein the participants are configured to send data in an uncoordinated manner relative to other participants and / or base stations of the communication system, wherein the participants are configured to receive synchronization data packets of point-to-multipoint data transmissions by base stations of the communication system, wherein the synchronization data packets are transmitted in a specified or participant-known frequency range of the frequency band of the communication system, wherein the participants are configured to receive, based on the synchronization data packets, payload data packets of the point-to-multipoint data transmissions that are referenced to the synchronization data packets in time and / or frequency [e.g., synchronized; e.g., at specified time and / or frequency intervals and / or in a time hopping pattern and / or a frequency hopping pattern].

[0022] In an embodiment, a payload data packet of a point-to-multipoint data transmission may be divided into a plurality of partial payload data packets for transmission, wherein the plurality of partial payload data packets each comprise a portion of the payload data packet, and wherein the plurality of partial payload data packets are transmitted distributed over time [e.g., across a plurality of time slots] and / or frequency [e.g., across a plurality of frequency channels] according to a time hopping and / or frequency hopping pattern, wherein a synchronization data packet comprises information about the time hopping and / or frequency hopping pattern, and wherein a participant is configured to receive the plurality of partial payload data packets based on the information about the time hopping and / or frequency hopping pattern.

[0023] In an embodiment, multiple partial payload data packets may be transmitted according to a frequency hopping pattern [e.g., and optionally, a time hopping pattern], wherein the reception bandwidth of the participant's receiver is at least 5 times [e.g., 10 times] smaller than the occupied bandwidth [e.g., frequency channel] of the frequency band indicated by the frequency hopping pattern.

[0024] In an embodiment, a participant may be configured to switch a receiving frequency of a participant's receiver to a corresponding frequency or frequency channel of a frequency band indicated by the frequency hopping pattern based on the frequency hopping pattern [e.g., at a corresponding time or time slot indicated by the time hopping pattern] to receive multiple partial payload data packets.

[0025] In an embodiment, the synchronization data packet may include synchronization information [eg, a synchronization sequence], wherein the participant is configured to synchronize itself [eg, its clock generator and / or timer and / or frequency generator] with the synchronization information.

[0026] In an embodiment, a participant is configured to send an uplink data transmission to a base station of a communication system and to receive a downlink data transmission from the base station in time synchronization with the sent uplink data transmission, wherein the downlink data transmission includes signaling information, and wherein the participant is configured to receive synchronization data packets of the point-to-multipoint data transmission based on the signaling information.

[0027] In an embodiment, the signaling information may include information on a time point [eg, a time slot] of transmission of the synchronization data packet.

[0028] In an embodiment, the signaling information may include information about the frequency range in which the synchronization data packets are transmitted [eg, so that the participants are aware of the frequency range].

[0029] In an embodiment, the downlink data transmission further comprises clock generator correction information for correcting a clock deviation of a clock generator of the participant, wherein the participant is configured to correct the clock deviation of the clock generator based on the clock generator correction information.

[0030] In an embodiment, the synchronization data packet is transmitted multiple times such that the duration of the multiple transmissions of the synchronization data packet is greater than or equal to the maximum possible time offset between the participant and the base station.

[0031] For example, the time span between the start of a first transmission and the start of a last transmission may correspond at least to the time offset between the terminal point and the base station.

[0032] In an embodiment, a participant's reception window [eg, time search range] for receiving synchronization packets [eg, in a single or multiple transmissions of synchronization packets] is larger than a maximum possible time offset between the participant and the base station.

[0033] In an embodiment, the synchronization data packet may be transmitted multiple times, wherein the participant is configured to receive the synchronization packet by using at least two receiving windows, [e.g., wherein the two receiving windows are shorter in time than a maximum time offset between the base station and the participant], wherein an interval between successive transmissions of the multiple transmissions of the synchronization data packet and an interval between the at least two receiving windows of the participant are coprime with respect to each other.

[0034] In an embodiment, the synchronization data packet may be transmitted multiple times, wherein a first transmission of the synchronization data packet and a second transmission of the synchronization data packet are versions of each other that are offset in time and / or frequency.

[0035] In an embodiment, the synchronization data packet may be repeatedly transmitted, wherein the repeated transmission of the synchronization data packet is periodic, wherein the participant is configured to receive the synchronization data packet by exploiting the periodicity of the repeated transmission of the synchronization data packet [eg, based on a cyclic correlation].

[0036] In an embodiment, a synchronization data packet of a point-to-multipoint data transmission is divided into a plurality of partial synchronization data packets for transmission, wherein each of the plurality of partial synchronization data packets comprises a portion of a synchronization data packet, and wherein the plurality of partial synchronization data packets are transmitted distributedly in time [e.g., across a plurality of time slots] and / or frequency [e.g., across a plurality of frequency channels] according to a specified or participant-known time-hopping and / or frequency-hopping pattern, wherein the participants are configured to receive the plurality of partial synchronization data packets based on the specified or participant-known time-hopping and / or frequency-hopping pattern.

[0037] In an embodiment, the downlink data transmission may include information about the time hopping and / or frequency hopping pattern of the synchronization data packets [eg, so that the participants are aware of the time hopping and / or frequency hopping pattern of the synchronization data packets].

[0038] In an embodiment, a plurality of partial synchronization packets may be transmitted according to a time and / or frequency hopping pattern of the synchronization packets within a specified or participant-known frequency range, which at most corresponds to a reception bandwidth of a participant's receiver.

[0039] In an embodiment, the partial synchronization packets are channel coded such that only a subset of the plurality of partial synchronization packets are required to successfully decode the synchronization packet, wherein the participant is configured to receive and decode at least a portion of the plurality of partial synchronization packets to obtain the synchronization packet.

[0040] In an embodiment, the designated or participant-known frequency range includes one or more partial frequency ranges, and wherein the designated or participant-known frequency range is wider than a receiving bandwidth of a participant's receiver, wherein, according to a time hopping and / or frequency hopping pattern of the synchronization data packets, for each partial frequency range within the designated frequency range, at least as many partial synchronization data packets as are required for successfully decoding the synchronization data packets are transmitted among a plurality of partial synchronization data packets, wherein each of the one or more partial frequency ranges corresponds at most to a receiving bandwidth of a participant's receiver.

[0041] In an embodiment, the plurality of partially synchronized data packets are transmitted a plurality of times such that a duration of the plurality of transmissions of the plurality of partially synchronized data packets is greater than or equal to a maximum possible time offset between the participant and the base station.

[0042] For example, the time span between the start of a first transmission and the start of a last transmission may correspond at least to the time offset between the terminal point and the base station.

[0043] In an embodiment, a receiving window of a participant for receiving the plurality of partially synchronized data packets [eg, in a single or multiple transmissions of the plurality of partially synchronized data packets] is larger than a maximum possible time offset between the participant and the base station.

[0044] In an embodiment, the plurality of partially synchronized data packets are transmitted multiple times, wherein the participant is configured to receive the plurality of partially synchronized data packets by using at least two receive windows [e.g., wherein the two receive windows are shorter in time than a maximum time offset between a base station and the participant], wherein an interval between successive transmissions of the multiple transmissions of the plurality of partially synchronized data packets and an interval between the at least two receive windows of the participant are coprime with respect to each other.

[0045] In an embodiment, multiple partially synchronized data packets are repeatedly transmitted, wherein a first transmission of the multiple partially synchronized data packets according to a time hopping and / or frequency hopping pattern and a second transmission of the multiple partially synchronized data packets according to the time hopping and / or frequency hopping pattern are versions of each other that are offset in time and / or frequency.

[0046] In an embodiment, multiple partial synchronization data packets are repeatedly transmitted, wherein a first transmission of the multiple partial synchronization data packets according to a time hopping and / or frequency hopping pattern is within a first partial frequency range of a frequency range specified or known to the participant, and wherein a second transmission of the multiple partial synchronization data packets according to the time hopping and / or frequency hopping pattern is within a second partial frequency range of a frequency range specified or known to the participant, wherein the first partial frequency range is different from the second partial frequency range.

[0047] In an embodiment, the first partial frequency range and the second partial frequency range are separated in frequency to such an extent that unintentional synchronization with the respective other specified partial frequency range caused by frequency offsets [eg by quartz offsets of a participant or a base station] is not possible.

[0048] In an embodiment, the frequency hopping pattern indicates an occupancy of frequency channels, wherein immediately consecutive frequency channels indicated by the frequency hopping pattern are separated in terms of frequency to such an extent that they do not overlap even with a frequency offset.

[0049] In an embodiment, the frequency hopping pattern indicates an occupancy of frequency channels, wherein the occupancy of frequency channels indicated by the frequency hopping pattern does not include any repeated identical frequency intervals between immediately consecutive frequency channels.

[0050] In an embodiment, the time hopping pattern indicates an occupancy of time slots, wherein the occupancy of time slots indicated by the time hopping pattern does not include any repeated identical time intervals between immediately consecutive time slots.

[0051] In an embodiment, multiple partially synchronized data packets are repeatedly transmitted, wherein a first transmission of the multiple partially synchronized data packets according to a time hopping and / or frequency hopping pattern and a second transmission of the multiple partially synchronized data packets according to the time hopping and / or frequency hopping pattern are interleaved with each other [e.g., such that the first transmitted and the second transmitted partial synchronized data packets are transmitted alternately [e.g., implicitly resulting in a frequency hopping pattern with a time interval corresponding to the number of repetitions]].

[0052] For example, the frequency hopping pattern may be selected such that the above-described interleaving is possible.

[0053] In an embodiment, a first transmission of multiple partially synchronized data packets according to a time and / or frequency hopping pattern and a second transmission of multiple partially synchronized data packets according to the time and / or frequency hopping pattern are frequency and / or time offset versions of each other.

[0054] In an embodiment, the plurality of partially synchronized data packets are repeatedly transmitted, wherein the repeated transmission of the plurality of partially synchronized data packets is periodic, wherein the participant is configured to receive the plurality of partially synchronized data packets by adopting the periodicity of the repeated transmission of the plurality of partially synchronized data packets [e.g., based on a cyclic correlation].

[0055] In an embodiment, the participant is configured to receive the plurality of partial synchronization packets by employing a periodicity of repeated transmission of the plurality of partial synchronization packets based on a cyclic correlation of the partial synchronization levels.

[0056] In an embodiment, the number of the plurality of partially synchronized data packets depends on a code rate of error protection of payload data packets of the point-to-multipoint data transmission.

[0057] In an embodiment, [eg, all] the partial synchronization data packets in the plurality of partial synchronization data packets are of the same sign.

[0058] In an embodiment, synchronization data packets [eg, multiple partial synchronization data packets] and payload data packets of a point-to-multipoint data transmission are encoded with the same error protection code.

[0059] In an embodiment, synchronization data packets [eg, multiple partial synchronization data packets] and payload data packets of a point-to-multipoint data transmission are encoded with error protection codes of similar performance.

[0060] In an embodiment, the frequency range specified or known to the participant may include at least one frequency channel of a frequency band.

[0061] In an embodiment, the designated or participant-known frequency range comprises a plurality of frequency channels of a frequency band, wherein at least two frequency channels of the plurality of frequency channels are spaced apart from each other to an extent that the two frequency channels are within a frequency bandwidth corresponding to a reception bandwidth of a receiver of the participant.

[0062] In an embodiment, the receiver of the participant comprises a reception bandwidth corresponding to the bandwidth of two to ten [eg two to four] immediately adjacent frequency channels into which the frequency band of the communication system is divided.

[0063] In an embodiment, a participant's receiver may include a reception bandwidth of 250 kHz or less [eg, or 100 kHz].

[0064] In an embodiment, a participant may be configured to transmit data asynchronously with other participants and / or base stations of the communication system.

[0065] For example, a participant may be configured to asynchronously send uplink data transmissions to a base station.

[0066] In an embodiment, a participant may be configured to send uplink data transmissions to a base station at random or pseudo-random time points.

[0067] In an embodiment, the uplink data transmission may include a plurality of sub-data packets transmitted distributed in time and / or frequency according to a time and / or frequency hopping pattern.

[0068] For example, uplink data transmission may be data transmission based on telegram splitting. In data transmission based on telegram splitting, data to be transmitted [e.g., (encoded) physical layer payload data] is divided into a plurality of sub-data packets, so that each of the plurality of sub-data packets only includes a portion of the data to be transmitted, wherein the plurality of sub-data packets are not transmitted continuously, but are distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern.

[0069] In an embodiment, a downlink data transmission may include a plurality of sub-data packets transmitted distributed in time and / or frequency according to a time and / or frequency hopping pattern.

[0070] For example, downlink data transmission may be data transmission based on telegram splitting. In data transmission based on telegram splitting, data to be transmitted [e.g., (encoded) physical layer payload data] is divided into a plurality of sub-data packets, so that each of the plurality of sub-data packets only includes a portion of the data to be transmitted, wherein the plurality of sub-data packets are not sent continuously, but are distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern.

[0071] In an embodiment, an actor may be a sensor node or an actuator node.

[0072] In an embodiment, the participant may be battery powered.

[0073] In an embodiment, a participant may include an energy harvesting element for generating electrical energy.

[0074] A further embodiment provides a base station of a communication system, [wherein the communication system communicates wirelessly in a frequency band [e.g., an ISM band] used by a plurality of [e.g., [mutually uncoordinated] communication systems], wherein the base station is configured to send point-to-multipoint data transmissions to uncoordinated transmitting participants of the communication system, wherein the point-to-multipoint data transmissions include synchronization data packets and payload data packets that are referenced to the synchronization data packets in time and / or frequency [e.g., synchronized; e.g., sent at specified time and / or frequency intervals and / or in a time hopping pattern and / or a frequency hopping pattern], wherein the synchronization data packets are transmitted in a frequency range of the frequency band of the communication system that is specified or known to the participants.

[0075] In an embodiment, a base station is configured to transmit a payload data packet of a point-to-multipoint data transmission that is divided into a plurality of partial payload data packets, wherein the plurality of partial payload data packets each comprise a portion of the payload data packet, and wherein the plurality of partial payload data packets are transmitted distributed in time [e.g. across a plurality of time slots] and / or frequency [e.g. across a plurality of frequency channels] according to a time hopping and / or frequency hopping pattern, wherein the base station is configured to provide information about the time hopping and / or frequency hopping pattern to a synchronization data packet.

[0076] In an embodiment, the base station is configured to transmit a plurality of partial payload data packets according to a frequency hopping pattern [e.g. and optionally a time hopping pattern], wherein the bandwidth of the occupation of the frequency band [e.g. frequency channel] indicated by the frequency hopping pattern is at least 5 times [e.g. 10 times] smaller than the reception bandwidth of the participant's receiver.

[0077] In an embodiment, the base station is configured to provide synchronization information [eg, synchronization sequence] for synchronization of the participants to the synchronization data packet.

[0078] In an embodiment, the base station is configured to receive an uplink data transmission from one of the participants and send a downlink data transmission to the participant in time synchronization with the uplink data transmission, wherein the downlink data transmission comprises signaling information, wherein the signaling information signals a synchronization data packet.

[0079] In an embodiment, the signaling information includes information about a time point [eg a time slot] of transmission of the synchronization data packet.

[0080] In an embodiment, the signaling information includes information about the frequency range over which the synchronization data packets are transmitted [eg so that the participants are aware of the frequency range].

[0081] In an embodiment, the base station is configured to determine a clock deviation of a participant's clock generator [e.g., a deviation of the clock of the clock generator from a reference clock] based on the uplink data transmission, wherein information about the time point or frequency of the point-to-multipoint data transmission included in the signaling information takes into account the clock deviation of the participant's clock [e.g., thereby compensating for the clock deviation of the clock].

[0082] In an embodiment, the base station is configured to determine a clock deviation of a participant's clock generator [e.g., a deviation of the clock of the clock generator from a reference clock] based on an uplink data transmission, wherein the base station is configured to further provide clock correction information to the downlink data transmission for correcting the clock deviation of the participant's clock generator.

[0083] In an embodiment, the base station is configured to transmit the synchronization data packet multiple times such that the duration of the multiple transmissions of the synchronization data packet is greater than or equal to a maximum possible time offset between the participant and the base station.

[0084] For example, the base station can be configured to transmit synchronization data packets multiple times until and / or select the distance between the synchronization data packets so that the time span between the start of the first transmission of the synchronization data packet and the start of the last transmission of the synchronization data packet at least corresponds to the time offset between the terminal point and the base station.

[0085] In an embodiment, the base station is configured to transmit the synchronization data packet multiple times, wherein a first transmission of the synchronization data packet and a second transmission of the synchronization data packet are versions of each other that are offset in time and / or frequency.

[0086] In an embodiment, the base station may be configured to repeatedly transmit the synchronization data packet, wherein the repeated transmission of the synchronization data packet is periodic.

[0087] In an embodiment, the base station is configured to transmit a synchronization data packet of a point-to-multipoint data transmission that is divided into a plurality of partial synchronization data packets, wherein the plurality of partial synchronization data packets each comprises a portion of the synchronization data packet, and wherein the plurality of partial synchronization data packets are transmitted distributed in time [e.g. across a plurality of time slots] and / or frequency [e.g. across a plurality of frequency channels] according to a specified or participant-known time hopping or frequency hopping pattern.

[0088] In an embodiment, the base station is configured to provide information about the time and / or frequency hopping pattern of the synchronization data packets for the downlink data transmission.

[0089] In an embodiment, the base station is configured to transmit a plurality of partial synchronization data packets according to a time hopping and / or frequency hopping pattern of the synchronization data packets within a specified or participant-known frequency range, wherein the specified or participant-known frequency range corresponds at most to a reception bandwidth of a participant's receiver.

[0090] In an embodiment, the base station is configured to channel encode the partial synchronization packets such that only a subset of the plurality of partial synchronization packets are required to successfully decode the synchronization packets.

[0091] In an embodiment, the frequency range specified or known to the participant comprises one or more partial frequency ranges.

[0092] In an embodiment, the frequency range ratio specified or known to the participant is wider than the reception bandwidth of the participant's receiver, wherein the base station is configured to transmit at least as many partial synchronization data packets of the plurality of partial synchronization data packets as are required for successfully decoding the synchronization data packets for each partial frequency range within the specified frequency range according to the time hopping and / or frequency hopping pattern of the synchronization data packets, wherein each of the one or more partial frequency ranges corresponds at most to the reception bandwidth of the participant's receiver.

[0093] In an embodiment, the base station may be configured to transmit the plurality of partial synchronization packets a plurality of times such that a duration of the plurality of transmissions of the plurality of partial synchronization packets is greater than or equal to a maximum possible time offset between the participant and the base station.

[0094] In an embodiment, the base station may be configured to transmit the plurality of partially synchronized data packets multiple times, wherein intervals between subsequent transmissions of the plurality of transmissions of the plurality of partially synchronized data packets and intervals between receive windows based on which participants receive the plurality of partially synchronized data packets are coprime with respect to each other.

[0095] In an embodiment, the base station may be configured to repeatedly transmit a plurality of partial synchronization data packets, wherein a first transmission of the plurality of partial synchronization data packets according to a time hopping and / or frequency hopping pattern and a second transmission of the plurality of partial synchronization data packets according to the time hopping and / or frequency hopping pattern are time-shifted versions of each other.

[0096] In an embodiment, the base station can be configured to repeatedly transmit multiple partial synchronization data packets, wherein the first transmission of the multiple partial synchronization data packets according to the time hopping and / or frequency hopping pattern is within a first partial frequency range of a specified or participant-known frequency range, and wherein the second transmission of the multiple partial synchronization data packets according to the time hopping and / or frequency hopping pattern is within a second partial frequency range of a specified or participant-known frequency range, wherein the first partial frequency range is different from the second partial frequency range.

[0097] In an embodiment, the first partial frequency range and the second partial frequency range are separated in frequency to such an extent that an unintentional synchronization with the respective other specified partial frequency range caused by a frequency offset is not possible.

[0098] In an embodiment, the frequency hopping pattern may indicate an occupancy of frequency channels, wherein immediately consecutive frequency channels indicated by the frequency hopping pattern are separated in terms of frequency to such an extent that they do not overlap even with a frequency offset.

[0099] In an embodiment, the frequency hopping pattern indicates an occupancy of frequency channels, wherein the occupancy of frequency channels indicated by the frequency hopping pattern does not include any repeated identical frequency intervals between immediately consecutive frequency channels.

[0100] In an embodiment, the time hopping pattern may indicate an occupancy of time slots, wherein the occupancy of time slots indicated by the time hopping pattern does not include any repeated identical time intervals between immediately consecutive time slots.

[0101] In an embodiment, the base station may be configured to repeatedly transmit a plurality of partial synchronization data packets, wherein a first transmission of the plurality of partial synchronization data packets according to a time hopping and / or frequency hopping pattern is interleaved with a second transmission of the plurality of partial synchronization data packets according to the time hopping and / or frequency hopping pattern [e.g., such that the first transmitted and the second transmitted partial synchronization data packets are transmitted alternately].

[0102] In an embodiment, a first transmission of multiple partially synchronized data packets according to a time and / or frequency hopping pattern and a second transmission of multiple partially synchronized data packets according to the time and / or frequency hopping pattern are frequency and / or time offset versions of each other.

[0103] In an embodiment, the base station may be configured to repeatedly transmit a plurality of partial synchronization data packets, wherein the repeated transmission of the plurality of partial synchronization data packets is periodic.

[0104] In an embodiment, the number of the plurality of partially synchronized data packets depends on a code rate of error protection of payload data packets of the point-to-multipoint data transmission.

[0105] In an embodiment, [eg, all] of the partial synchronization packets in the plurality of partial synchronization packets are of the same sign.

[0106] In an embodiment, synchronization data packets [eg, multiple partial synchronization data packets] and payload data packets of a point-to-multipoint data transmission are encoded with the same error protection code.

[0107] In an embodiment, synchronization data packets [eg, multiple partial synchronization data packets] and payload data packets of a point-to-multipoint data transmission are encoded with error protection codes of similar performance.

[0108] A further embodiment provides a method of operating an uncoordinated transmission participant of a communication system. The method comprises the step of receiving a synchronization data packet of a point-to-multipoint data transmission of a base station of the communication system, wherein the synchronization data packet is transmitted in a frequency range specified or known to the participant in a frequency band of the communication system. And, the method comprises the step of receiving a payload data packet of the point-to-multipoint data transmission that is referenced in time and / or frequency to the synchronization data packet [e.g., synchronized; e.g., transmitted at specified time and / or frequency intervals] based on the synchronization data packet.

[0109] A further embodiment provides a method for operating a base station of a communication system. The method comprises the steps of transmitting a point-to-multipoint data transmission to a plurality of non-coordinated transmission participants of the communication system, wherein the point-to-multipoint data transmission comprises a synchronization data packet and a payload data packet referenced in time and / or frequency [e.g., synchronized; e.g., at a specified time and / or frequency interval and / or time hopping pattern and / or frequency hopping pattern] to the synchronization data packet, wherein the synchronization data packet is transmitted in a frequency range of a frequency band of the communication system that is specified or known to the participants. BRIEF DESCRIPTION OF THE DRAWINGS

[0110] Embodiments of the present invention are described in more detail with reference to the accompanying drawings, in which:

[0111] Figure 1 A schematic diagram shows the frequency band occupation of a TSMA-based communication system in the transmission of a data packet divided into a plurality of sub-data packets, wherein the plurality of sub-data packets are distributed in time and frequency,

[0112] Figure 2 A schematic diagram shows frequency band occupancy in the transmission of a plurality of uplink messages and a plurality of downlink messages in a contention-based communication system,

[0113] Figure 3 A schematic diagram of a communication system having a base station and one or more participants and two other communication systems according to an embodiment of the present invention is shown.

[0114] Figure 4 The base station and Figure 3 Schematic block diagram of a base station and one of the participants of the communication system shown in,

[0115] Figure 5 is a schematic diagram of frequency band occupation of a communication system when a base station performs multiple uplink data transmissions and downlink data transmissions with multiple participants, and point-to-multipoint data transmissions from the base station to multiple participants according to an embodiment of the present invention,

[0116] Figure 6 shows a schematic circuit block diagram of a participant and a base station according to an embodiment of the present invention,

[0117] Figure 7 A schematic diagram showing frequency band occupancy of a communication system according to an embodiment of the present invention when performing uplink data transmission, downlink data transmission and point-to-multipoint data transmission,

[0118] Figure 8 A schematic diagram showing frequency band occupancy of a communication system according to an embodiment of the present invention when performing a first uplink data transmission, a first downlink data transmission, a second uplink data transmission, and a second downlink data transmission,

[0119] Fig. 9 is a schematic diagram showing frequency band occupation of a communication system according to an embodiment of the present invention when performing uplink data transmission, downlink data transmission, beacon transmission as a support for further data transmission, and point-to-multipoint transmission,

[0120] Fig.10 shows a schematic circuit block diagram of a participant and a base station according to an embodiment of the present invention,

[0121] Fig.11 shows the frequency band occupation of a communication system with point-to-multipoint data transmission with synchronization data packets and payload data packets according to an embodiment of the present invention, wherein the payload data packets are divided into a plurality of partial payload data packets,

[0122] Fig.12 A schematic diagram shows the frequency band occupation of a communication system in a point-to-multipoint data transmission with a synchronization data packet and a payload data packet according to an embodiment of the present invention, wherein the synchronization data packet is divided into a plurality of partial synchronization data packets and the payload data packet is divided into a plurality of partial payload data packets,

[0123] Fig.13 shows the occupation of a specified frequency channel in repeated transmission of a synchronization data packet according to an embodiment of the present invention, wherein the synchronization data packet is divided into a plurality of partial synchronization data packets distributed in a specified frequency range for transmission according to a time hopping and frequency hopping pattern,

[0124] Fig.14 shows the frequency band occupation of a communication system in the transmission of a point-to-multipoint data transmission with a plurality of partial payload data packets according to an embodiment of the present invention, and the repeated transmission of partial synchronization data packets on different partial frequency ranges of a specified frequency range,

[0125] Fig.15 shows the frequency band occupation of a communication system in transmission of a point-to-multipoint data transmission with a plurality of partial payload data packets according to an embodiment of the present invention, and repeated transmission of partial synchronization data packets, wherein the repeated transmission of the partial synchronization data packets are interleaved with each other,

[0126] Fig.16 A schematic diagram shows the occupation of a specified frequency range in the periodic transmission of partial synchronization data packets and the reception window of a receiver of a participant for receiving the partial synchronization data packets according to an embodiment of the present invention,

[0127] Fig.17 A schematic diagram shows the occupation of a specified frequency range in the periodic transmission of partial synchronization data packets according to an embodiment of the present invention, and a reception window of a receiver of a participant receiving the partial synchronization data packets, wherein the length of the reception window corresponds to the length of four partial synchronization data packets,

[0128] Fig.18 A schematic diagram shows the occupation of a specified frequency range in the repeated transmission of a partial synchronization data packet according to an embodiment of the invention, and two reception windows of a receiver of a participant for receiving the partial synchronization data packets, wherein the repeated transmissions of the partial synchronization data packets are versions of each other that are shifted in time and frequency,

[0129] Fig.19 A flowchart showing a method for operating an uncoordinated transmission participant of a communication system according to an embodiment of the present invention, and

[0130] Fig. 20 A flow chart of a method for operating a base station of a communication system according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0131] In the following description of the embodiments of the present invention, the same elements or elements having the same function are given the same reference numerals in the drawings so that their description is interchangeable.

[0132] Before describing in detail the embodiments of the participants (eg, terminal points) and the base station, Figure 3 and 4 The underlying communication system that may use participants and / or base stations is described in more detail.

[0133] Figure 3 A schematic diagram of a communication system 100 and two other communication systems 101 and 102 according to an embodiment of the present invention is shown.

[0134] The communication system 100 may include a base station 104 (or optionally several base stations) and one or more participants (eg, terminal points) 106_1-106_n, where n is a natural number greater than 1. Figure 3 In the illustrated embodiment, for illustrative purposes, the communication system 100 includes five participants 106_1-106_5, however, the communication system 104_1 may also include 1, 10, 100, 1,000, 10,000 or even 100,000 participants.

[0135] The communication system 100 may be configured to communicate wirelessly in a frequency band (e.g., an unlicensed and / or license-exempt frequency band, such as an ISM frequency band) used for communication by multiple mutually non-coordinated communication systems, as exemplified in Figure 3 , the two devices communicate via other communication systems 101 and 102 .

[0136] The frequency band used by the communication system 100 may have a significantly larger bandwidth (eg, at least 5 times (or 10 times)) than the receive filters of the receivers (or transceivers) of the participants 106_1 - 106_n.

[0137] Participants 106_1-106_n of the communication system 100 may be configured to transmit data in an uncoordinated manner (e.g., and asynchronously) relative to other participants and / or the base station 104 of the communication system 100. For example, participants 106_1-106_n may be configured to transmit data at specified coarse intervals (e.g., hourly, daily, weekly, semi-annually, annually, etc.) or as a reaction to external events (e.g., deviations of sensor values ​​from target values). In this case, the respective participant may determine the exact time point and / or the exact frequency of the transmission, or the exact frequency channel of the frequency band, for the transmission of the data. In this case, the respective participant transmits the data regardless of whether another participant and / or the base station 104 transmits data at the same time point or with time overlap and / or on the same frequency or on the same frequency channel of the frequency band.

[0138] In this case, the transmission of data (e.g., data packets) from one of the participants 106_1-106_n, such as data transmission from the participant 106_1 to the base station 104 is referred to as uplink data transmission, and the transmission of data from the base station 104 to one of the participants 106_1-106_n, such as to the participant 106_1, is referred to as downlink data transmission. Therefore, uplink data transmission refers to (or includes) the transmission of uplink data packets (or uplink messages) from the corresponding participant to the base station 104, and downlink data transmission refers to (or includes) the transmission of downlink data packets (or downlink messages) from the base station 104 to the corresponding participant.

[0139] Since the uplink data transmission of the respective participants 106_1-106_n occurs uncoordinatedly and the sending / receiving units (transceivers) of the respective participants 106_1-106_n are usually activated only for data transmission, the downlink data transmission to the respective participants is synchronized in time with the uplink data transmission, i.e. after a specified time and / or frequency after the uplink data transmission, the respective participants activate their sending / receiving units (transceivers) within a specified time interval (receiving window) in order to receive the downlink data transmission sent exactly in this time interval as a response (e.g., reaction) to the uplink data transmission by the base station 104. Optionally, the downlink data transmission to the respective participants may also be synchronized in frequency with the respective uplink data transmission, e.g., it may be on the same frequency (in the same frequency channel) or with a specified frequency interval.

[0140] This has the advantage that the participants 106_1-106_n only have to activate their sending / receiving units (transceivers) for the respective data transmission (uplink data transmission and / or downlink data transmission) (e.g. in normal operating mode), while their sending / receiving units can be deactivated (e.g. into energy saving mode) for the rest of the time to save energy. In particular, this is advantageous if the respective participant has only limited energy, e.g. because it is powered by batteries or collects energy from the surrounding area by means of energy harvesting elements.

[0141] For example, participants 106_1-106_n of the communication system 100 may be actuator nodes and / or sensor nodes, such as heat meters, motion detectors, smoke detectors, and the like.

[0142] Optionally, the base station 104 and the participants 106_1-106_n of the communication system 100 can be configured to transmit data based on a telegram splitting method. In this case, at the data transmitter, the data to be transmitted, such as a telegram or a data packet (e.g., a physical layer in the OSI model), such as an uplink data packet or a downlink data packet, is divided into a plurality of sub-data packets (or partial data packets), and the sub-data packets are not transmitted continuously, but are distributed in time and / or frequency according to a time hopping and / or frequency hopping mode, wherein the sub-data packets are merged (or combined) at the data receiver end to obtain a data packet. In this case, each sub-data packet contains only a portion of the data packet. In addition, the data packet can be encoded (channel coding or error protection coding) so that the data packet can be decoded error-free without all sub-data packets, but only part of the sub-data packets are required.

[0143] As mentioned above, the distribution of the plurality of sub-data packets in time and / or frequency may be performed according to a time hopping and / or frequency hopping pattern.

[0144] The time-hopping pattern may indicate a sequence of transmission time points or transmission time intervals used to transmit the sub-data packets. For example, a first sub-data packet may be transmitted at a first transmission time point (or in a first transmission time slot), and a second sub-data packet may be transmitted at a second transmission time point (or in a second transmission time slot), wherein the first transmission time point and the second transmission time point are different. In this case, the time-hopping pattern may define (or specify or indicate) the first transmission time point and the second transmission time point. Alternatively, the time-hopping pattern may indicate the first transmission time point and the time interval between the first transmission time point and the second transmission time point. Obviously, the time-hopping pattern may also indicate only the time interval between the first transmission time point and the second transmission time point. Between the sub-data packets, there may be a transmission pause in which no transmission occurs. The sub-data packets may also overlap (coincide) in time.

[0145] The frequency hopping pattern may indicate the transmission frequency used to transmit the sub-data packet or the sequence of transmission frequency hopping. For example, the first sub-data packet may be transmitted with a first transmission frequency (or in a first frequency channel), and the second sub-data packet may be transmitted with a second transmission frequency (or in a second frequency channel), wherein the first transmission frequency is different from the second transmission frequency. In this case, the frequency hopping pattern may define (or specify or indicate) the first transmission frequency and the second transmission frequency. Alternatively, the frequency hopping pattern may indicate the first transmission frequency and the frequency interval between the first transmission frequency and the second transmission frequency (transmission frequency hopping). Obviously, the frequency hopping pattern may also only indicate the frequency interval between the first transmission frequency and the second transmission frequency (transmission frequency hopping).

[0146] Obviously, multiple sub-packets can also be transmitted in a distributed manner in time and frequency. The distribution of multiple sub-packets in time and frequency can be performed according to a time hopping and frequency hopping pattern. The time hopping and frequency hopping pattern can be a combination of a time hopping pattern and a frequency hopping pattern, i.e. a sequence of transmission time points or a transmission time interval of the transmission sub-packets, wherein the transmission frequency (or transmission hopping frequency) is assigned to the transmission time point (or transmission time interval).

[0147] In this case, the occupied bandwidth of the frequency band indicated by the frequency hopping pattern may be much larger (e.g., at least 5 times (or 10 times)) than the bandwidth of the reception filter of the receiver (receiver or transceiver) of the participants 106_1-106_n. In order to receive the data transmission based on telegram splitting, the corresponding participants can therefore be configured to switch the reception frequency of their receivers to the corresponding frequencies or frequency channels of the frequency band indicated by the frequency hopping pattern based on the frequency hopping pattern (e.g., at the corresponding times or time slots indicated by the time hopping pattern) to receive multiple sub-data packets.

[0148] Figure 4 The base station 104 and Figure 3A schematic block circuit diagram of one of the participants 106_1 - 106_n of the communication system 100 is shown.

[0149] Participant 106_1 may include a transmitter (or transmission module) 108_1 configured to transmit an uplink data transmission 120 to base station 104. Transmitter 108_1 may be connected to antenna 110_1 of participant 106_1. In addition, participant 106_1 may include a receiver (or reception module) 112_1 configured to receive a downlink data transmission 122 from base station 104. Receiver 112_1 may be connected to antenna 110_1 or another antenna of participant 106_1. Participant 106_1 may also include a combined transmitter / receiver (e.g., a transmit / receive module; a transceiver).

[0150] The base station 104 may include a receiver (or receiving module) 114 configured to receive an uplink data transmission 120 from the participant 106_1. The receiver 114 may be connected to an antenna 116 of the base station 104. In addition, the base station 104 may include a transmitter (or transmitting module) 118 configured to transmit a downlink data transmission 122 to the participant 106_1. The transmitter 118 may be connected to the antenna 116 or another antenna of the base station 104. The base station 104 may also include a combined transmitter / receiver (or transmitting / receiving module; transceiver).

[0151] For example, about Figure 3 and Figure 4 The described communication system 100 may be a LPWAN (Low Power Wide Area Network), as defined in the standard ETSI TS 103 357 [4].

[0152] The embodiment of the participant 106_1 and the base station 104 can be used exemplarily for the above Figure 3 and Figure 4 In the communication system 100 described herein, this will be described below. Obviously, the embodiments of the participant 106_1 and / or the base station 104 described below can also be implemented in other communication systems with non-coordinated transmission participants.

[0153] 1. Signaling multicast messages in an uncoordinated network

[0154] The embodiments described below enable multicast messages (point-to-multipoint data transmission) from the base station 104 to the participants 106_1-106_n or a portion (actual subset) of the participants 106_1-106_n in the uncoordinated communication system 100, where the participants 106_1-106_n transmit data to the base station 104 asynchronously.

[0155] For example, this can be done as Figure 5 As shown, this is implemented, wherein, during the transmission of the multicast message (point-to-multipoint data transmission) 124, there is preferably no other data transmission (e.g., overlapping / covering the point-to-multipoint data transmission 124) (e.g., uplink data transmission 120 and / or downlink data transmission 122).

[0156] In detail, Figure 5 The frequency band occupancy of the communication system 100 when performing a number of uplink data transmissions 120 and a downlink data transmission 122 between a base station 104 and a number of participants 106_1-106_n according to an embodiment of the present invention, as well as a point-to-multipoint data transmission 124 from the base station 104 to a plurality of participants 106_1-106_n is shown in the form of a schematic diagram. Figure 5 In the example, the ordinate describes frequency and the abscissa describes time. In other words, Figure 5 An example of a multicast message (point-to-multipoint data transmission) 124 in an uncoordinated communication system is shown.

[0157] For according to Figure 5 The participants 106_1-106_n or a subset of the participants 106_1-106_n of the communication system 100 receive such a multicast message (point-to-multipoint data transmission) 124. In an embodiment, the point-to-multipoint data transmission 124 is performed or the participants 106_1-106_n can receive other information based on the time point t at which the point-to-multipoint data transmission 124 is received. multicast The signal is sent as described below.

[0158] Figure 6 1 shows a schematic block diagram of a participant 106_1 and a base station 104 according to an embodiment of the present invention.

[0159] Participant 106_1 (eg, a terminal point) may be configured to be relatively independent of base station 104 and / or other participants of communication system 100 (see Figure 3 )Send data uncoordinatedly.

[0160] In addition, participant 106_1 can be configured to send an uplink data transmission 120 to base station 104, and receive a downlink data transmission 122 from base station 104 that is time-synchronized with the uplink data transmission 120, wherein the downlink data transmission 122 includes signaling information, wherein the signaling information indicates or signals the base station 104 of a subsequent point-to-multipoint data transmission 124 and / or a further data transmission (e.g., a data transmission in preparation for the point-to-multipoint data transmission) before the point-to-multipoint data transmission 124.

[0161] Furthermore, the participant 106_1 may be configured to receive a point-to-multipoint data transmission (eg, a multicast data transmission) 124 from the base station 104 based on the signaling information.

[0162] The base station 104 can be configured to receive an uplink data transmission 120 from the participant 106_1 and send a downlink data transmission 122 to the participant 106_1 in time synchronization with the received uplink data transmission 120, wherein the downlink data transmission 122 includes signaling information, wherein the signaling information indicates or signals the base station 104 of a subsequent point-to-multipoint data transmission 124 and / or a further data transmission (e.g., a data transmission in preparation for the point-to-multipoint data transmission) before the point-to-multipoint data transmission 124.

[0163] Furthermore, base station 104 may be configured to transmit point-to-multipoint data transmission 124 to participant 160 (and, for example, to one or more other participants of communication system 100) in accordance with the signaling information.

[0164] In an embodiment, the signaling information may include information about a point in time of the point-to-multipoint data transmission 124. For example, the information about the point in time may be an absolute point in time, a relative point in time (e.g. a defined time span between the downlink data transmission 122 and the point-to-multipoint data transmission 124), or information from which an absolute or relative point in time can be derived, such as a number of clock cycles of a clock generator (oscillator) of a participant.

[0165] In an embodiment, the signaling information may additionally or alternatively include information about the frequency or frequency channel (e.g., of a frequency band used by the communication system) of the point-to-multipoint data transmission 124. For example, the information about the frequency may be an absolute frequency or a relative frequency (e.g., the interval between the frequency of the downlink data transmission 122 and the frequency of the point-to-multipoint data transmission 124). For example, the information about the frequency channel may be an absolute frequency channel or a relative frequency channel (e.g., the distance between the frequency channel of the downlink data transmission 120 and the frequency channel of the point-to-multipoint data transmission 124).

[0166] In an embodiment, the point-to-multipoint data transmission 124 may include a plurality of sub-data packets that are sent distributed in time and frequency according to a time hopping and / or frequency hopping pattern (telegram segmentation transmission method). In this case, the signaling information may further include information about the time hopping and / or frequency hopping pattern of the point-to-multipoint data transmission 124. For example, the point-to-multipoint data transmission 124 may be a data transmission based on telegram segmentation. In a data transmission based on telegram segmentation, the data to be transmitted (e.g., (coded) payload data of the physical layer) is divided into a plurality of sub-data packets, so that each of the plurality of sub-data packets includes only a portion of the data to be transmitted, wherein the plurality of sub-data packets are not transmitted continuously, but are distributed in time and / or frequency according to the time hopping and / or frequency hopping pattern.

[0167] A detailed embodiment of the participant 106_1 and the base station 104 is described in more detail below.

[0168] 1.1 Signaling in previous downlink packets

[0169] In addition to messages for multiple participants 106_1-106_n, the base station 104 typically transmits a single message to the participants 106_1-106_n, such as a verified confirmation or a parameter change for the corresponding participant. Since this is separate for each participant, a separate downlink must be transmitted.

[0170] This is where an embodiment of the present invention is implemented by appending the sending time point of the subsequent multicast message (point-to-multipoint data transmission) 124 to the individually transmitted downlink message (downlink data transmission) 122.

[0171] If multiple frequency channels are available, in addition to the signaling of the transmission time, information about the transmission channel may also be added (eg, signaled).

[0172] By this signaling, the participant now knows the time point and possibly the frequency channel of the upcoming multicast message (point-to-multipoint data transmission) 124. With the help of the same method, other participants can also synchronize to the multicast message (point-to-multipoint data transmission) 124.

[0173] If no individual data is to be sent to a participant, in this case only the time point and possibly the frequency channel can be transmitted in the upcoming downlink message (downlink data transmission) 124 .

[0174] The advantage of this approach is that the time point and possibly the frequency channel are shared only with the participants (the plurality of participants 106_1-106_n of the communication system 100) that will receive the multicast message (point-to-multipoint data transmission) 124. Therefore, for the participants that do not receive the multicast message (point-to-multipoint data transmission) 124, there is no additional effort to increase battery consumption.

[0175] Figure 7 The signaling process of a multicast message (point-to-multipoint data transmission) 124 from an uplink message (uplink data transmission) 120 to the actual multicast message (point-to-multipoint data transmission) 124 for one participant of an uncoordinated radio network (communication system) 100 is shown exemplarily.

[0176] In detail, Figure 7 The frequency band occupancy of the communication system 100 according to the embodiment of the present invention when performing uplink data transmission 120, downlink data transmission 122 and point-to-multipoint data transmission 124 is shown in the form of a schematic diagram. Figure 7In the diagram, the vertical axis describes the frequency and the horizontal axis describes the time.

[0177] from Figure 7 As can be seen in FIG. 1 , the downlink data transmission 122 occurs synchronously in time with the uplink data transmission 120, for example, after a specified (defined) time after the uplink data transmission 120. The downlink data transmission 122 includes signaling information indicating or signaling a subsequent point-to-multipoint data transmission 124.

[0178] like Figure 7 As shown, for example, the signaling information may include information about the time point of the point-to-multipoint data transmission 124. Obviously, the signaling information may also include information about the frequency or frequency channel of the point-to-multipoint data transmission 124 in addition or in lieu thereof.

[0179] In an embodiment, if the point-to-multipoint data transmission 124 is transmitted based on a telegram splitting transmission method (TSMA, Telegram Splitting Multiple Access), the signaling information may include information about a time hopping and / or frequency hopping pattern of the point-to-multipoint data transmission 124 .

[0180] In other words, if TSMA is used for the transmission of multicast messages (point-to-multipoint data transmission) 124, the hopping pattern (time hopping and / or frequency hopping pattern) may additionally be signaled, if this has not been globally defined in advance.

[0181] In an embodiment, information about the transmission time point and / or the transmission channel (transmission frequency) and / or the frequency hopping pattern (only in TSMA) may be appended to a separately generated downlink data packet (eg, downlink data transmission 120) to the participants.

[0182] [4] In the downlink, a so-called authentication wake-up message and / or authentication message is defined. With the help of this message, the base station 104 can send a confirmation of a previous uplink message to a participant individually. If further personal data of the participant are available, the length of this data and the interval between the message and the subsequent data are also signaled in this message. Now, if there is signaling of a multicast message to a participant and there is no further personal data for the participant, then in addition to the wake-up message and the authentication message, an additional transmission can be used for the signaling of the multicast message.

[0183] In the case of only signaling a multicast message (point-to-multipoint data transmission) 124, fields containing additional information (length and time information, or PSI and TSI in [4]) of the following data can also be used for direct signaling of the multicast message (point-to-multipoint data transmission) 124 (time, frequency, length, etc.). This reduces the overhead required for separate transmissions in addition to wake-up and authentication messages.

[0184] In an embodiment, in case only a multicast message (point-to-multipoint data transmission) 124 is signaled, available fields in the wake-up message and / or the authentication message (downlink data transmission according to [4]) can be used for this.

[0185] 1.2 Coarse Time Signaling

[0186] According to Section 1.1, it often takes a long time to inform all necessary participants of an upcoming multicast message (point-to-multipoint data transmission) 124. In particular, in cases where the participants are informed of the upcoming multicast message (point-to-multipoint data transmission) 124 very early, very large time differences are signaled. Being able to solve this problem in a suitably sophisticated manner requires the transmission of many bits. In the case of participants being informed very close (in time) to the actual multicast message (point-to-multipoint data transmission) 124, the high bits of the bits of the data field are located in the signaling with the same resolution.

[0187] It follows from this that, depending on the (time) difference between signaling and multicast message (point-to-multipoint data transmission) 124, sequences of different lengths are meaningful for the signaling.

[0188] However, when considering real participants including Quartz, it is clear that the inaccuracy of the time point at which the participant expects the multicast message (point-to-multipoint data transmission) 124 also depends on the time difference between signaling and the multicast message (point-to-multipoint data transmission) 124.

[0189] The longer the difference, the less accurate the time point assumed by the participant for the multicast message (point-to-multipoint data transmission) 124. The less accurate this time point is, the larger the search range for the multicast message (point-to-multipoint data transmission) 124 chosen by the participant. If the search range is significantly larger than the resolution of the transmission time point of the multicast message (point-to-multipoint data transmission) 124, a lower resolution (and therefore a larger uncertainty) can be chosen without significantly increasing the search range (in the worst case, the quartz error and the resolution error are added).

[0190] Typical values ​​of inaccuracy in signaling range from 1 symbol (eg, symbol duration) to ten 10,000 symbols (symbol duration).

[0191] Values ​​(eg, symbol duration) above 10,000 symbols have too large an accuracy and require very extensive post-synchronization.

[0192] In the case of ideal timing, it is important to note that the uncertainty is still large enough that reception without post-synchronization is impossible.

[0193] In an embodiment, the resolution of the signaling may include a certain inaccuracy that may be determined in the context of post-sync.

[0194] Instead of or in combination with a coarse signaling of the time points, a non-linear scaling of the time points, for example a logarithmic scale, may be chosen. This has the advantage that time points close to an upcoming multicast message (point-to-multipoint data transmission) 124 have a more precise resolution than more distant time points. However, according to the above explanation, this is not critical, since the inaccuracy increases with the (time) interval of the multicast message (point-to-multipoint data transmission) 124 due to quartz offsets (e.g. frequency offsets of the quartz). Therefore, the resolution may also therefore become less accurate, the further in the future the time points of the multicast message (point-to-multipoint data transmission) 124 are.

[0195] In an embodiment, the resolution of the signaling may include non-linear scaling.

[0196] 1.3 Signalling of further uplink messages

[0197] For the signaling of the time point of the multicast message (point-to-multipoint data transmission) 124 according to Section 1.1 or Section 1.2, for example, a variable with 16 bits is typically transmitted. In the case of the exemplary selected quantization of 1 s per LSB (least significant bit), the maximum difference between the signaling and the multicast message (point-to-multipoint data transmission) 124 is 65536 seconds. This is approximately 18 hours.

[0198] Therefore, it should be ensured that all required participants of a multicast message (point-to-multipoint data transmission) 124 can be notified within 18 hours prior to the message.

[0199] Typically, in large networks with hundreds of thousands of participants (e.g., nodes) 106_1-106_n, this is not possible, since there may be participants that transmit data only once a day or less frequently to the base station 104. Therefore, using the above parameters, it is not possible to notify all participants (e.g., nodes) of an upcoming multicast message (point-to-multipoint data transmission) 124, or to send them the same signal.

[0200] Therefore, in an embodiment, instead of the time point of the multicast message (point-to-multipoint data transmission) 124, the (approximate) time at which the participant should / must send the uplink message (uplink data transmission) 120 to the base station 104 can again be shared with all participants who were temporarily notified of the multicast message (point-to-multipoint data transmission) 124 before the maximum signaling length.

[0201] If this new uplink message (uplink data transmission) 120 is sent by a participant, the base station 104 can then send back a downlink message (downlink data transmission) 122 and inform the time point of the multicast message (point-to-multipoint data transmission) 124 therein.

[0202] The time series of this mode is Figure 8 . In this case, the (rough) time of a further uplink message (second uplink data transmission) 120_2 is transmitted in a first downlink message (first downlink data transmission) 122_1. Information about the time point and / or frequency of a multicast message (point-to-multipoint data transmission) 124 then follows in a second downlink message (second downlink data transmission) 122_2.

[0203] In detail, Figure 8 The schematic diagram shows the frequency band occupancy of the communication system 100 according to the embodiment of the present invention when performing the first uplink data transmission 120_1, the first downlink data transmission 122_1, the second uplink data transmission 120_1, the second downlink data transmission 122_2 and the point-to-multipoint data transmission 124. Figure 8 The vertical axis describes the frequency and the horizontal axis describes the time.

[0204] from Figure 8 As can be seen in FIG. 1 , the first downlink data transmission 122 occurs synchronously with the first uplink data transmission 120_1 in time, for example after a specified (defined) time after the first uplink data transmission 120_1. The first downlink data transmission 122 includes first signaling information.

[0205] The first signaling information may indicate or signal a further data transmission before the point-to-multipoint data transmission 124 (eg, a data transmission in preparation for the point-to-multipoint data transmission), wherein Figure 8 In the illustrated embodiment, the further data transmission may include both a second uplink data transmission 120_2 and a second downlink data transmission 122_2 after the same time synchronization.

[0206] like Figure 8 As shown, the first signaling information may signal a time span or a time point (e.g., a rough time point) of a second uplink data transmission 120_2, wherein the second uplink data transmission 122_2 occurs in the time span, or at a rough time point, signaled by the first signaling information, and wherein the second downlink data transmission 122_2 occurs synchronously in time with the second uplink data transmission 120_2, for example, after a specified (defined) time after the first uplink data transmission 120_1. The second downlink data transmission 122_2 may include second signaling information, wherein the second signaling information indicates or signals a subsequent point-to-multipoint data transmission 124 of the base station 104.

[0207] For example, Figure 8As shown, the second signaling information may include information about the time point of the point-to-multipoint data transmission 124. Obviously, the second signaling information may additionally or alternatively include information about the frequency or frequency channel of the point-to-multipoint data transmission 124. If the point-to-multipoint data transmission 124 is transmitted based on the telegram split transmission method (TSMA, telegram split multiple access), the second signaling information may additionally or alternatively include information about the time hopping and / or frequency hopping pattern of the point-to-multipoint data transmission 124.

[0208] In other words, Figure 8 Signaling for the time of a further uplink message (e.g., a second uplink data transmission) 120_2 is shown, wherein the further uplink message (e.g., a second uplink data transmission) 120_2 is followed by a further downlink message (second downlink data transmission) 122_2, for example, defining the time of a multicast message (e.g., a point-to-multipoint data transmission) 124.

[0209] If a participant sends messages to the base station 104 less frequently, for example only once a week, further uplink messages (uplink data transmissions) may also be requested multiple times as long as the time required for signaling is within the valid range.

[0210] In an embodiment, instead of signaling the time points of multicast messages (point-to-multipoint data transmission), (rough, approximate) times can be defined at which participants should / must send further uplink messages.

[0211] Due to the lack of coordination of the communication system (radio network) 100, there may be interference and failures in transmission. The communication system 100 described here often operates in an unlicensed frequency band and where the communication system 100 shares resources with other communication systems (see Figure 3 ), where the communication system 100 and other communication systems are not coordinated with each other. Therefore, there may also be interference from third-party communication systems.

[0212] Using the telegram splitting transmission method, a method has been developed which includes a very high interference robustness, however, a maximum probability of getting through cannot be guaranteed.

[0213] If the participant has been informed according to Section 1.3 of further transmission of uplink messages (uplink data transmission), the participant may expect a reliable response from the base station 104 in the downlink (eg, in the form of a downlink data transmission).

[0214] However, if a participant does not receive a downlink message (downlink data transmission) or an erroneous / faulty / corrupted message, the participant knows that something in the transmission did not go correctly (eg, due to channel interference).

[0215] In this case, the participant can immediately send a further uplink message (e.g. a third uplink data transmission) to the base station 104 (e.g. a repetition of a previous uplink message (e.g. a second uplink data transmission 120_2)). It then waits for a downlink message (e.g. a third downlink data transmission) for the base station 104 again. If this is received correctly again, it is ensured that the uplink message (e.g. the third uplink data transmission) has now correctly arrived at the base station 104. Otherwise, the participant can open another reception window (e.g. for a further downlink data transmission) (if this is known to the base station 104) or perform another transmission of an uplink message (uplink data transmission).

[0216] In an embodiment, if a further uplink message (e.g. a second uplink data transmission) that is (roughly) signaled in time does not obtain a correct answer in the downlink (e.g. in the form of a second downlink data transmission), a further uplink message may be sent (immediately) (e.g. a third uplink data transmission).

[0217] As an alternative to signaling the multicast message (point-to-multipoint data transmission) 124, the time point of the multicast message (point-to-multipoint data transmission) 124 can still be shared, however, with another resolution (e.g., in the range of 1 minute to 1.5 months). The participants can then decide for themselves when (before the multicast message (point-to-multipoint data transmission) 124) they send an uplink message again (e.g., the fourth uplink data transmission) to obtain a more precise time point (point-to-multipoint data transmission 124).

[0218] In this way, a participant can wait, for example, up to 1 hour before a multicast message (point-to-multipoint data transmission) 124 whether an uplink message (uplink data transmission) is needed, thereby obtaining an accurate point in time. If this is not the case, the participant can send a dedicated uplink message (e.g., the fourth uplink data transmission). In this case, the dedicated uplink message (e.g., the fourth uplink data transmission) should obviously be (pseudo) randomly placed in the remaining time so that not all participants (e.g., nodes) do not have the precise time synchronization for the one-time transmission of the multicast message (point-to-multipoint data transmission) 124.

[0219] In an embodiment, a greater resolution can be selected in the signaling at a point in time, in case the participants are informed long before the actual multicast message. Then, tentatively, the participants can wait to see whether there has been an uplink message (uplink data transmission) shortly before the multicast message (point-to-multipoint data transmission) 124. If this is not the case, a dedicated uplink message (e.g. the fourth uplink data transmission) can be triggered.

[0220] 1.4 Support for signaling of beacon time and / or frequency channels

[0221] In an embodiment, a so-called support beacon may be used before transmitting a multicast message (point-to-multipoint data transmission) 124. Such a support beacon may contain signaling until the next support beacon or multicast message (point-to-multipoint data transmission) 124.

[0222] In an embodiment, a participant (of the communication system 100) may synchronize with this support beacon. In the same manner as in Section 1.1, for example, the time before the support beacon and the frequency channel of the support beacon that may be used may be signaled, such as Fig. 9 Indicated schematically.

[0223] Fig. 9 FIG. 1 is a schematic diagram showing frequency band occupancy of the communication system 100 according to an embodiment of the present invention when performing uplink data transmission 120, downlink data transmission 122, and point-to-multipoint data transmission 124. Fig. 9 In the diagram, the vertical axis describes the frequency and the horizontal axis describes the time.

[0224] from Fig. 9 As can be seen in FIG. 1 , the downlink data transmission 122 occurs synchronously in time with the uplink data transmission 120, for example, after a specified (defined) time after the uplink data transmission 120. The downlink data transmission 122 includes first signaling information.

[0225] The first signaling information may indicate or signal a further data transmission prior to the point-to-multipoint data transmission 124 (eg, a data transmission in preparation for the point-to-multipoint data transmission). Fig. 9 In the embodiment shown, the further data transmission is a support beacon 123 .

[0226] like Fig. 9As shown, the first signaling information may include information about the time point of the support beacon 123. Obviously, the first signaling information may also additionally or alternatively include information about the frequency or frequency channel of the support beacon. If the support beacon 123 is transmitted based on the telegram split transmission method (TSMA, telegram split multiple access), the first signaling information may additionally or alternatively also include information about the time hopping and / or frequency hopping mode of the support beacon 124.

[0227] The supporting beacon may include second signaling information, wherein the second signaling information indicates or signals further supporting beacons or subsequent point-to-multipoint data transmission 124 of the base station 104 .

[0228] For example, Fig. 9 As shown, the second signaling information may include information about the time point of the point-to-multipoint data transmission 124. Obviously, the second signaling information may additionally or alternatively also include information about the frequency channel of the point-to-multipoint data transmission 124. If the point-to-multipoint data transmission 124 is transmitted based on the telegram segmentation transmission method (TSMA, telegram segmentation multiple access), the second signaling information may additionally or alternatively also include information about the time hopping and / or frequency hopping pattern of the point-to-multipoint data transmission 124.

[0229] In other words, Fig. 9 The signaling of the time and possible frequency offset from the participant's message (downlink data transmission 120) to the supporting beacon 123 is shown.

[0230] In an embodiment, information about the transmission time and / or transmission channel (transmission frequency) and / or frequency hopping pattern (only in the case of TSMA) of supported beacons can be added to a separately generated downlink data packet (e.g., downlink data transmission 120) to the participants.

[0231] 1.5 Quartz offset compensation

[0232] As already mentioned in section 1.2, the participants 106_1-106_n and the base station 104 usually have an oscillating quartz for generating an internal reference frequency (e.g. as a clock generator). However, these quartz are not ideal and have so-called tolerances on the available frequencies. These tolerances are also transferred to the internal reference frequency.

[0233] Among other things, the transmission frequency and the timers fed by these reference frequencies determine the time difference between messages. Therefore, the tolerance of the quartz directly affects the transmission and reception of messages.

[0234] For example, in [4] the reception frequency of the participant is estimated from the uplink message (uplink data transmission) and the downlink transmission frequency is modified so that the participant can receive the downlink message (downlink data transmission) without a frequency offset. In other words, the characteristics of the downlink message (downlink data transmission) are adjusted according to the participant's (quartz's) frequency offset so that the participant no longer sees the quartz's frequency offset.

[0235] This mode works perfectly as long as there is only communication between one base station 104 and one participant 106_1. If the base station 100 communicates with two or more participants 106_1-106_n, the base station 104 obtains a different frequency offset generated by the corresponding quartz for each of the participants 106_1-106_n.

[0236] Therefore, it is not possible to send a multicast message (point-to-multipoint data transmission) 124 to all participants 106_1-106_n in such a way that all participants 106_1-106_n do not see any or only ignore low frequency offsets and / or time offsets through quartz.

[0237] Due to its admissible tolerance, each participant (eg, node) must perform time and frequency synchronization at the beginning of a multicast message (point-to-multipoint data transmission) 124 .

[0238] Starting from a typical oscillating quartz with a tolerance range of 20ppm and a maximum signaling length of about 18 hours, as shown in the example in Section 1.3, there is a maximum time inaccuracy of the participant at the time of transmitting the multicast message (point-to-multipoint data transmission) 124 of 65536s*20ppm=1.31s. Therefore, for the correct time point, the participant must search within a search range of ±1.31s before and after the expected time point of the multicast message (point-to-multipoint data transmission) 124.

[0239] The same applies to frequency deviations, where with a typical carrier frequency of 900 MHz the maximum deviation that the respective participants have to search for is ±18 kHz.

[0240] If the participant has a fast processor for real-time searching, it can determine the correct time point and frequency offset without extensive storage requirements. However, if the search cannot be performed in real-time, all baseband data can instead be stored for subsequent offline evaluation.

[0241] In the second case, the participants usually have only very small microprocessors on which the errors are so large that it is impossible to fully store the baseband data.

[0242] Consider the following example: the data rate of the multicast message (point-to-multipoint data transmission) 124 is 5 kHz. In the case of the above-mentioned quartz offset of 20 ppm, the bandwidth to be searched is therefore 2*18 kHz+5 kHz=41 kHz. Therefore, when using an SDR front end in baseband (I phase and Q phase), the sampling rate is also at least 41 ksamples / s. Therefore, within the above-mentioned search range of ±1.31 seconds, 107,420 samples must be available to be buffered in memory for processing. For a typical ADC resolution of 16 bits (16 bits for I phase and 16 bits for Q phase), this requires at least 429,680 KB of random access memory. Typical values ​​for random access memory on small microprocessors are less than 100 KB (e.g. 64 KB). Therefore, the entire search range cannot be processed offline.

[0243] Both cases also require a very high computational effort and therefore significantly increase the current consumption, which is particularly important for battery-powered actors.

[0244] Therefore, large search ranges in both the time direction and the frequency direction must be avoided.

[0245] In some systems, the participants also have more than one quartz, for example LF quartz (LF = low frequency) and HF quartz (HF = high frequency). LF quartz usually requires less current than HF quartz. Therefore, the LF quartz is usually operated continuously and the timing is derived from this. However, the radio chip requires a higher frequency clock and is therefore operated using the HF quartz. Therefore, the transmission frequency depends on the HF quartz. Due to current consumption reasons, the HF quartz can be switched off between transmissions.

[0246] LF quartz typically has a higher tolerance than HF quartz. For example, LF quartz might have a tolerance of 100ppm, while HF quartz might have a tolerance of, for example, 20ppm.

[0247] As already mentioned, a measurement / estimation of the carrier frequency is performed in [4]. The frequency offset can be determined with the help of the expected carrier frequency and the quartz error can be determined from this. Alternatively or in combination with the estimation of the carrier frequency, the time interval (between two telegrams / data packets / transmissions or within one transmission in the case of telegram splitting) can also be measured to estimate the deviation of the quartz.

[0248] This offset or these offsets can also be transmitted in the downlink (ie together with the downlink data transmission) together with the parameters from the previous sections 1.1 to 1.4. As a result, the participant now knows its quartz offset at the transmission time of the uplink message (uplink data transmission).

[0249] Alternatively, an average quartz offset from several previous uplink messages (uplink data transmissions) may be used, and / or if the temperature is available, the temperature dependency may also be considered (information temperature normalized frequency deviation).

[0250] When the method of determining the quartz offset by time offset is used, the cumulative offset (e.g., time offset) can also be determined. Here, the base station 104 knows the time between two arbitrary transmissions (e.g., uplink data transmissions), i.e., not necessarily two consecutive transmissions. Now, the base station 104 receives two transmissions (e.g., uplink data transmissions) and determines the time offset between the transmissions (e.g., uplink data transmissions). From this, the cumulative quartz offset (e.g., time offset) can be determined. Therefore, the quartz offset caused by the temperature deviation during the time between two transmissions (e.g., uplink data transmissions) is accumulated, because the quartz must be continuously running to determine the transmission time point, and therefore, the current environmental conditions always have an impact on the quartz.

[0251] If the quartz offset is determined via the transmission frequency, the situation is different, since only the offset (eg frequency offset) at the current transmission time has an influence on the transmission frequency.

[0252] Typically, the environmental conditions of the respective participants do not change immediately, so it can be assumed that, if the current quartz offset (e.g. the frequency offset of the quartz) is known, the maximum error over time between the signaling (point-to-multipoint data transmission) 124 and the actual transmission (point-to-multipoint data transmission 124) of the multicast message is less than the maximum allowed quartz offset.

[0253] This reduces the search range in both the time direction and the frequency direction, thus saving computing power, storage space and energy. When the same parameters are selected as in the previous example, except for the quartz offset in the respective participant which is corrected based on the values ​​in this case from the previous uplink message (uplink data transmission), the maximum possible remaining offset (e.g., residual frequency offset) is reduced to, for example, 5 ppm.

[0254] As a result, the maximum search range in the time direction is reduced to 328 ms, or in the frequency direction to 4.5 kHz. As a result, only one-quarter of the storage space is required, and the computing power is reduced accordingly.

[0255] If more than one quartz is installed in the respective participant, the base station 104 can also determine the offset (e.g. frequency offset) of several quartzes accordingly and signal the same (e.g. in the downlink data transmission). Alternatively, the quartz can also be coupled in the participant (e.g. node). As a result, (e.g. all) quartzes (of the respective participant) have the same offset (e.g. frequency offset). In this case, it is sufficient if the base station 104 estimates the offset (e.g. frequency offset) of only one quartz, since the respective participant can directly apply the offset to the other quartzes.

[0256] In an embodiment, the quartz offset of a participant can be determined from an uplink message (uplink data transmission) and the participant can be informed in a subsequent downlink message (downlink data transmission). The participant can correct for this offset when receiving a multicast message (point-to-multipoint data transmission) and select a smaller search window accordingly.

[0257] As an alternative to signaling a quartz offset (e.g., a frequency offset of quartz) from the uplink (e.g., an uplink data transmission), the base station 104 can also use the quartz offset to adapt the signaled time points of the multicast messages (point-to-multipoint data transmission). To this end, the base station 104 can calculate the deviation of the time point taking into account the quartz offsets of the participants (e.g., terminal points) and signal a "wrong" or corrected time point accordingly. The same applies to the signaling of the frequency channels and, if applicable, the signaling of the frequency hopping pattern in the case of telegram splitting.

[0258] Therefore, a participant does not have to know anything about its quartz offset and can assume a small quartz error when searching for the start of a multicast message (point-to-multipoint data transmission) (see above).

[0259] In an embodiment, the quartz offset (eg, frequency offset of the quartz) of the participants may be taken into account when signaling the start time (eg, point-to-multipoint data transmission 124) and may be modified accordingly in the base station 104.

[0260] 2. Point-to-multipoint data transmission with synchronization packets for participant synchronization

[0261] It is assumed below that there is one coordination instance (eg, base station 104 ) and non-coordinating participants (eg, terminal devices or terminal points) 106_1 - 106_n within each network (or communication system) 100 .

[0262] For the operation of low-power wide area networks (LPWANs), message transmission in the form of the telegram splitting method (telegram splitting multiple access) has proven to be particularly advantageous. [1], [2], [5] illustrate the basis of this transmission method by way of example. In this case, a message (data packet (e.g. physical layer in the OSI model)) is divided into a number of partial data packets and transmitted over different time / frequency resources. The sequence in which the partial data packets are transmitted in time and / or frequency is called a channel access pattern or frequency hopping pattern.

[0263] In the case of channel access methods, contention-based access is often used, for example, in LPWAN networks. Here, there are no resources specifically allocated to the participants (e.g., terminal devices) 106_1-106_n, but rather multiple participants (e.g., terminal devices) 106_1-106_n actively access a common directory of radio resources. Therefore, there may be access conflicts, i.e., two or more participants occupy radio resources at the same time. In order to minimize the impact of such access conflicts, the participants (e.g., terminal devices) 106_1-106_n are provided with different channel access patterns (frequency hopping patterns).

[0264] If the base station 104 wants to send a message to a participant (e.g., terminal device) 106_1, this is done at defined time and frequency points (receive windows). Otherwise, the participant (terminal device) would not be able to receive the message (e.g., data packets; e.g., downlink data transmission) with its limited resources. In order to transmit messages to multiple participants (e.g., terminal devices) 106_1-106_n simultaneously (multicast), the receive windows of the participants (terminal devices) 106_1-106_n must be tuned to each other.

[0265] However, in normal operation, the participants (eg, terminal devices) 106_1 - 106_n operate completely asynchronously with the other participants and the base station 104.

[0266] Transmission by base station 104 to several participants (eg terminal nodes) is called multicast (point-to-multipoint data transfer). The special case of direct transmission to all participants (eg and terminals) is called broadcast. This is also covered by the embodiments.

[0267] A network (communication system) using the telegram splitting method occupies only a very small bandwidth for a single transmission of a partial data packet. However, since synchronization requires the reception of several partial data packets, and these partial data packets are distributed over a very large bandwidth by means of a frequency hopping method to reduce interference susceptibility, synchronization with the telegram splitting signal still requires the consideration of a large frequency range for initial synchronization.

[0268] In small (usually battery powered) (low cost) participants, such high rate data processing (as required by the above frequency ranges) is not available and the reception bandwidth required for this is usually not available. Therefore, it is not possible for the (low cost) participants to receive multicast messages (point-to-multipoint data transmission) without additional information.

[0269] This is where the subsequent embodiment begins, according to which a multicast message (point-to-multipoint data transmission) is preceded by a so-called synchronization (partial) data packet which can be used by the addressed participants for time and / or frequency synchronization.

[0270] Thus, the embodiments described below allow participants 106_1-106_n (e.g., including participant 106_1) operating in an asynchronous network (communication system) 100 to synchronize themselves to a message (point-to-multipoint data transmission 124) to multiple participants. In this case, participant 106_1 is unable to receive the broadband transmission (point-to-multipoint data transmission) 124 of the multicast message at full bandwidth and is unable to process it in real time.

[0271] In this case, the main aspect concerns the two-phase synchronization process, namely the establishment and detection process of the synchronization sequence in which the explicit information about the receiving window is used.

[0272] Fig.10 FIG. 4 shows a schematic circuit block diagram of a participant 106_1 and a base station 104 according to an embodiment of the present invention.

[0273] Participant 106_1 (eg, a terminal point) may be configured to be relatively independent of base station 104 and / or other participants of communication system 100 (see Figure 3 )Send data uncoordinatedly.

[0274] Furthermore, the participant 106_1 may be configured to receive a synchronization data packet 126 of a point-to-multipoint data transmission 124 of the base station 104 of the communication system 100 , wherein the synchronization data packet 126 is transmitted in a frequency range 125 of a frequency band 103 of the communication system 100 that is specified or known to the participant.

[0275] Furthermore, the participant 106_1 may be configured to receive a payload data packet 128 of the point-to-multipoint data transmission 124 that references the synchronization data packet 128 in time and / or frequency based on the synchronization data packet 126 .

[0276] The base station 104 can be configured to send a point-to-multipoint data transmission 124 to non-coordinated transmitting participants 106_1-106_n of the communication system 100, including participant 106_1, wherein the point-to-multipoint data transmission 124 includes a synchronization data packet 126 and a payload data packet 128 that is referenced in time and / or frequency (e.g., synchronized; e.g., transmitted at specified or defined time and / or frequency intervals) to the synchronization data packet 126, wherein the synchronization data packet 126 is transmitted in a frequency range 125 of a frequency band 103 of the communication system 100 specified or known to the participants 106_1-106_n.

[0277] In an embodiment, the synchronization data packet 126 may include synchronization information such as a synchronization sequence or a pilot sequence, wherein the participant 106_1 may be configured to synchronize itself with the synchronization information (e.g., the synchronization sequence). As a result, the participant 106_1 may know, for example, the (relative) time point (or time slot) and / or the (relative) frequency (or frequency channel) (transmitted) of the synchronization data packet 126. Based on the (relative) time point (or time slot) and / or the (relative) frequency (or frequency channel) of the synchronization data packet 126 and information about the time point (or time slot) and / or frequency (or frequency channel) and / or the frequency hopping pattern (e.g. in the case of TSMA) of the transmission of the payload data packet 128 (e.g. relative to or relative to the synchronization data packet 126), for example, wherein said information can be contained in the synchronization data packet 126 or can be derived from information transmitted together with the synchronization data packet 126, or is known to the participant 106_1 in any other way, such as from a previous downlink data transmission 122 or a (strictly) defined data transmission 122 in the system, the participant 106_1, which is actually sent uncoordinatedly (and asynchronously) relative to the base station 104, is able to receive the payload data packet 128 of the point-to-multipoint data transmission 124 of the base station 104.

[0278] In an embodiment, the point-to-multipoint data transmission 124 may be signaled using signaling information sent from the base station 104 to the participant 106_1, for example, via the downlink data transmission 122.

[0279] In detail, the participant 106_1 can be configured to receive a downlink data transmission 122 synchronized in time with the uplink data transmission 120 from the base station 104, wherein the downlink data transmission 122 includes signaling information, wherein the signaling information signals the transmission of the point-to-multipoint data transmission 124, or strictly speaking, the transmission of a synchronization data packet 126 of the point-to-multipoint data transmission 124.

[0280] In this case, the participant 106_1 may be configured to receive the synchronization data packet 126 of the point-to-multipoint data transmission 124 based on the signaling information.

[0281] In an embodiment, the signaling information may include at least one of the following:

[0282] - information about the point in time (e.g. time slot) at which the synchronization data packet 126 is transmitted,

[0283] - information about the (specified) frequency range 125 in which the synchronization data packets 126 are transmitted,

[0284] - Information about the time hopping and / or frequency hopping pattern, based on which the synchronization data packet 126 is transmitted.

[0285] For example, the information about the time point can be an absolute time point (or time slot), a relative time point (or time slot) (e.g., a defined time span between the transmission of the downlink data 122 and the transmission of the synchronization data packet 126), or information from which an absolute or relative time point (or time slot) can be derived, such as the number of clock cycles of the oscillator of participant 106_1.

[0286] For example, the information about the specified frequency range 125 may be an absolute frequency range, such as an absolute frequency channel (eg, c0, c1, c2; see Fig.11 ), or relative frequency ranges, such as a frequency channel (e.g., c4) of a downlink data transmission 122 and a specified frequency range (e.g., c4-c1=c3; c4-c2=c2; c4-c3=c1; see Fig.11 ) between the two.

[0287] For example, the synchronization data packet 126 can be transmitted based on a telegram segmentation transmission method (TSMA). In the transmission of the synchronization data packet 126 based on the telegram segmentation transmission method, the synchronization data packet 126 (e.g., the physical layer in the OSI model) can be divided into a plurality of partial synchronization data packets, so that each of the plurality of partial synchronization data packets only includes a portion of the synchronization data packet 126, wherein the plurality of partial synchronization data packets are not transmitted continuously, but are distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern in a specified frequency range 125.

[0288] A detailed embodiment of the participant 106_1 and the base station 104 is described in more detail below.

[0289] 2.1 Transmitting (partial) synchronization packets before payload packets for point-to-multipoint data transmission

[0290] Signals with multi-MHz bandwidth used in a typical network (eg, communication system) 100 generally cannot be received and / or processed simultaneously at their full bandwidth by participants 106_1-106_n using very cost-effective hardware and / or battery power.

[0291] Typically, the radio chips installed on such participants 106_1-106_n can provide bandwidths of several hundred kHz. Furthermore, the computing power of such participants 106_1-106_n is configured to make real-time processing of these bandwidths possible.

[0292] It is still possible for these participants 106_1-106_n to synchronize their reception windows to a multicast (eg point-to-multipoint data transmission) 124 of multiple participants 106_1-106_n, embodiments enabling transmission of the necessary information for reception windows with frequency and / or time location within a bandwidth of approximately 100 kHz.

[0293] After extracting the required data, participant 106_1 can determine the time position and / or frequency channel / frequency channel of the reception window (e.g., the frequency hopping pattern of the (partial) payload data packet of the point-to-multipoint data transmission 124) and receive the (partial) payload data packet of the multicast message (point-to-multipoint data transmission 124) accordingly by switching the carrier frequency.

[0294] For this purpose, so-called (partial) synchronization data packets 126 can be transmitted at a fixed defined frequency at a previously agreed upon time point in a time-defined interval before the payload data packet 128 of the point-to-multipoint data transmission 124. This (partial) synchronization data packet 126 can be used to determine the start of the payload data packet 128 of the point-to-multipoint data transmission 124.

[0295] If the payload data packet 128 of the point-to-multipoint data transmission 124 is transmitted via a channel access pattern (or a frequency hopping pattern), then this (partial) synchronization data packet 126 may further include information for deriving the channel access pattern (or frequency hopping pattern) and the time and frequency position of the payload data packet 128 of the point-to-multipoint data transmission 124, or this is agreed upon in another way in advance.

[0296] This transmission of a (partial) synchronization data packet 126 prior to the actual transmission (of the payload data packet 128 for the point-to-multipoint data transmission) is performed at Fig.11 In this case, the (partial) synchronization data packet 126 contains information about the channel access mode (e.g. frequency hopping mode) for the payload data packet 128 of the point-to-multipoint data transmission 124. The interval between the (partial) synchronization data packet 126 and the payload data packet 128 of the point-to-multipoint data transmission 124 may be strictly defined or may be available as information in the (partial) synchronization data packet 126.

[0297] In detail, Fig.111 shows the occupancy of the frequency band 103 of the communication system 100 in the transmission of a point-to-multipoint data transmission 124 with synchronization data packets 126 and payload data packets 128 according to an embodiment of the present invention. Fig.11 In , the ordinate describes the frequency (frequency channel) and the abscissa describes the time (time slot).

[0298] from Fig.11 As can be seen in FIG. 1 , the synchronization data packet 126 can be transmitted within the specified frequency range 125 ( Fig.11 For example, Fig.11 As shown, the designated frequency range 125 may include one frequency channel. Obviously, the designated frequency range 125 may also include more than one frequency channel, for example two or three frequency channels, if the designated frequency range 125 is smaller than the receiving bandwidth of the receiver of the participant 106_1. If the synchronization data packet 126 is transmitted based on the telegram splitting method, the designated frequency range 125 may also be larger than the receiving bandwidth of the receiver of the participant 106_1, depending on the channel coding used.

[0299] from Fig.11 It can be further seen in that the payload data packet 128 of the point-to-multipoint data transmission 124 can be transmitted based on a telegram segmentation method (TSMA). In this case, the payload data packet 128 (e.g., of the physical layer in the OSI model) can be divided into a plurality of partial payload data packets 128_1-128_i (i=8), wherein the plurality of partial payload data packets 128_1-128_i (i=8) are transmitted in a distributed manner in time (e.g., across a plurality of time slots) and / or frequency (e.g., across a plurality of frequency channels) according to a time hopping and / or frequency hopping pattern.

[0300] Therefore, the synchronization data packet 128 may include information about the time hopping and / or frequency hopping pattern, wherein the participant 106_1 may be configured to receive a plurality of partial payload data packets 128_1 - 128_i (i=8) based on the information about the time hopping and / or frequency hopping pattern.

[0301] In other words, Fig.11 The transmission of a (partial) synchronization data packet 126 prior to the actual transmission of a payload data packet 128 of a point-to-multipoint data transmission 124 is shown.

[0302] In an embodiment, a (partial) synchronization data packet 126, e.g. containing necessary information about the channel access mode / frequency hopping pattern of a payload data packet 128 for a point-to-multipoint data transmission 124, may be transmitted time-referenced prior to the transmission of the payload data packet 128 of the point-to-multipoint data transmission 124.

[0303] 2.2 Information to participants about upcoming multicasts (e.g. point-to-multipoint data transmission)

[0304] Typically, participants 106_1-106_n operate asynchronously in a network (e.g., communication system) 100 and are therefore prepared to receive messages (e.g., downlink data transmission 122) only after they have sent a telegram (e.g., uplink data transmission 120) to a base station 104, such as is the case in a communication system specified in ETSI standard TS 103 357 [4].

[0305] It is still possible for the participants (e.g., devices) 106_1-106_n to receive the multicast (e.g., point-to-multipoint data transmission) 124, each of which is individually notified of the upcoming multicast (e.g., point-to-multipoint data transmission) 124. In addition, the exact frequency of the multicast (e.g., point-to-multipoint data transmission) 124 can be transmitted, for example, as explained in Section 1.

[0306] In addition to signaling a multicast message (e.g., point-to-multipoint data transmission) 124 according to Section 1, the base station 104 may transmit information about the time and frequency of the actual quartz offset relative to the participant 106_1. One possibility is to directly inform the participant 106_1 of the quartz offset so that it can perform compensation itself.

[0307] In an embodiment, in addition to signaling the time point of a multicast message (e.g., a point-to-multipoint data transmission) 124 according to Section 1, information about the time and / or frequency and / or frequency hopping pattern relative to the current participant's quartz offset may be transmitted to each participant individually.

[0308] The information about the upcoming multicast (e.g. point-to-multipoint data transmission) 124 can also occur several days in advance. However, in this case, it should be taken into account that the quartz of the participant 106_1 may have significant deviations. For example, a simple clock quartz of ±60 ppm will have a deviation of ±36 seconds after 7 days. By using HF quartz calibration, this inaccuracy is reduced to 12 seconds in 7 days, for example an accuracy of ±20 ppm.

[0309] In an embodiment, instead of signaling the actual multicast start as described in Section 1 (e.g., the actual point-to-multipoint data transmission 124, i.e., the payload data packet 128 of the point-to-multipoint data transmission 124), the start of the (partial) synchronization data packet 126 of the point-to-multipoint data transmission 124 can be signaled in a separate downlink message (downlink data transmission 122).

[0310] 2.3 Divide the synchronization data packet into several partial synchronization data packets

[0311] At the beginning of Section 2, a (partial) synchronization data packet 126 was introduced which was transmitted in time reference to a subsequent payload data packet 128 of a point-to-multipoint data transmission 124. This (partial) synchronization data packet 126 may also contain information about how the channel access pattern (or frequency hopping pattern) of the payload data packets 128 of the point-to-multipoint data transmission 124 is composed.

[0312] Compared to the payload data packet 128 of the point-to-multipoint data transmission 124 which is usually divided into a plurality of partial data packets (eg, partial payload data packets) 128_1-128_i, Fig.11 The (partial) synchronization data packet 126 in the present embodiment shown in FIG. 1 is only a single transmission (eg occupied resource element).

[0313] If an interruption occurs during this transmission, the participants 106_1 - 106_n are typically unable to extract data from this (partial) synchronization data packet 126 .

[0314] Fig.11 The typical bandwidth of the medium frequency channels is below 50 kHz. However, the low cost participants 106_1-106_n can typically process frequencies up to 100 kHz or even higher in real time.

[0315] Therefore, it is possible for participants 106_1-106_n to receive and search in parallel via at least two frequency channels.

[0316] Advantageously, the (partial) synchronization data packets 126 are also divided by the telegram splitting transmission method. Due to the very limited size of the payload data in the (partial) synchronization data packets 126, usually no more than five partial data packets (eg partial synchronization data packets) are needed.

[0317] When using a coding that allows the loss of at least one partial data packet (e.g. a partial synchronization data packet), the frequency hopping pattern for the divided synchronization data packets 126 can be selected so that a larger bandwidth is occupied than the bandwidth that the low-cost participants can receive. The only important thing is that the low-cost participants can always receive at least a minimum number of the required frequency channels, regardless of the quartz drift.

[0318] Fig.12 Such an example is outlined in . Here, the synchronization data packet 126 is divided into three partial data packets (partial synchronization data packets) 126_1-126_k (k=3) and transmitted on the frequency channels c0 to c2. It is also possible to introduce pauses in the transmission between the partial data packets (partial synchronization data packets) 126_1-126_k (k=3) and to select different partial data packets 126_1-126_k (k=3) relative to the arrangement of the frequencies. It is only important that the participant 106_1 knows this structure (e.g., hopping pattern) in advance.

[0319] In detail, Fig.12 The schematic diagram shows the occupation of the frequency band 103 of the communication system 100 in the transmission of a point-to-multipoint data transmission 124 with synchronization data packets 126 and payload data packets 128 according to an embodiment of the present invention, wherein the synchronization data packets 126 are divided into a plurality of partial synchronization data packets 126_1-126_k (k=3), and the payload data packets 128 are divided into a plurality of partial payload data packets 128_1-128_i (i=8). Fig.12 In , the ordinate describes the frequency (frequency channel) and the abscissa describes the time (time slot). In other words, Fig.12 The subdivision of the synchronization data packet 126 into three partial data packets (partial synchronization data packets) 126_1 - 126_k (k=3) is shown, wherein these are transmitted on different frequencies.

[0320] from Fig.12 As can be seen from FIG. 1 , the partial synchronization data packets 126_1-126_k (k=3) can be transmitted in different frequency channels ( Fig.12 1 ). In this case, the specified frequency range 125 may be smaller than or equal to the reception bandwidth of the receiver of the participant 106_1. If the partial synchronization data packets 126_1-126_k (k=3) are channel coded, i.e. not all partial synchronization data packets 126_1-126_k are required for successful decoding of the synchronization data packet 126, but only some of the synchronization data packets 126_1-126_k are required, the specified frequency range 125 may also be larger than the reception bandwidth of the receiver of the participant 106_1, as long as it is ensured that at least a plurality of partial synchronization data packets 126_1-126_k are transmitted within the specified frequency range 125 according to each partial frequency range required for successful decoding of the synchronization data packet 126, wherein each of the one or more partial frequency ranges corresponds at most to the reception bandwidth of the receiver of the participant 106_1.

[0321] For the purpose of illustration, the synchronization packet 126 is Fig.12 In the embodiment, the synchronization data packet 126 can be divided into three partial synchronization data packets 126_1-126_k (k=3); in the embodiment, the synchronization data packet 126 can be divided into k partial synchronization data packets 126_1-126_k, k is a natural number greater than or equal to 2, k≥2.

[0322] In an embodiment, the transmission of the synchronization data packet 126 may be divided into partial data packets (partial synchronization data packets) 126_1-126_k, wherein these are placed so that the low-cost participant (more cost-efficient participant) 106_1 can receive at least a portion of these partial data packets (partial synchronization data packets) 126_1-126_k. That is, at least the number of partial data packets (partial synchronization data packets) 126_1-126_k required for trouble-free reception is within the bandwidth of the low-cost receiver.

[0323] 2.4 Sharing the sending and receiving load between the base station and participants

[0324] When the announcement of the multicast (e.g., point-to-multipoint data transmission) 124 occurs long before the multicast (e.g., point-to-multipoint data transmission) 124, the time difference between the expected transmission and the actual transmission may be several seconds, e.g., ±36 seconds, due to the reference time offset (e.g., caused by quartz offset) between the base station 104 and the participant 106_1. In order for the participant 106_1 to receive the minimum number of required symbols, the participant 106_1 must perform reception for a long time, e.g., 72 seconds, or for the base station 104 to send repetitions very frequently.

[0325] In an embodiment, the transmission of the synchronization data packet 126 may be repeated a plurality of times (e.g., the base station 104 may be configured to repeat the same number of times) such that the duration of the complete sequence (e.g., multiple transmissions of the synchronization data packet 126) is longer than the maximum offset (e.g., time offset) between the base station 104 and the participant 106_1.

[0326] In an embodiment, the search range of a receiver (eg, of participant 106_1 ) may be longer than the maximum possible time offset (eg, caused by quartz offset) between the base station 104 and participant 106_1 .

[0327] With regard to the first possibility, it is to be considered that the base station 104 usually has only a limited transmission time per time unit (e.g. SRD in EU with a duty cycle of 10% = 6 minutes per hour). In the case of the second possibility, the participant must perform a long reception. This may not be possible due to limited resources in the form of batteries, available RAM and CPU computing time. A solution is that the base station transmits the synchronization sequence (e.g. synchronization data packet 126) more frequently (e.g. multiple times) and the participant 106_1 searches for the transmission more frequently. Using intervals that are mutually prime between the transmission interval and the reception window interval, the probability of a transmission (e.g. synchronization data packet 126) occurring at a point in time in the reception window can be increased.

[0328] In an embodiment, the intervals between repeated transmissions of the (partial) synchronization data packets 126 may be relatively prime with respect to each other.

[0329] In an embodiment, the distances of the receiving windows of the participant 106_1 may be relatively prime to each other. For example, in the selection of the receiving window, the participant 106_1 may be configured to select distances that are relatively prime to each other.

[0330] Such an example is Fig.13 . The base station 104 sends a (partial) synchronization packet 126 (synchronization sequence) four times, and the participant 106_1 attempts to find the sequence three times. The intervals between the transmit and receive windows 129 (of the (partial) synchronization packet 126) can be chosen to be orthogonal (e.g., mutually prime) to increase the probability of overlap.

[0331] In detail, Fig.13 The occupancy of a specified frequency range 125 in a repeatedly transmitted synchronization data packet 126 according to an embodiment of the present invention is shown, wherein the synchronization data packet is divided into a plurality of partial synchronization data packets 126_1-126_k (k=3) according to a time hopping and frequency hopping pattern and is transmitted distributed within the specified frequency range. In this case, the ordinate describes the frequency and the abscissa describes the time. In other words, Fig.13 Multiple repetitions of (partial) synchronization data packets 126 and multiple searches for them are shown.

[0332] from Fig.13 It can be seen that the distance t1 between the receiving windows 129 of the participants and the distance t2 between the repeated transmissions of the synchronization data packet 126 or the repeated transmissions of multiple partial synchronization data packets 126_1-126_k (k=3) may be relatively prime to each other.

[0333] 2.5 Frequency changes of (partial) synchronization packets

[0334] In the embodiments described in sections 2.1, 2.3 and 2.4, (partial) synchronization data packets 126 are transmitted on the same frequency or the same (adjacent) frequency to enable low-cost participants to have synchronization on the payload data packets 128 of the point-to-multipoint data transmission 124.

[0335] The transmission of the payload data packets 128 of the point-to-multipoint data transmission 124 takes place over a larger frequency range. This increases the interference reliability of the payload data packets 128 of the point-to-multipoint data transmission 124 compared to the (partial) synchronization data packets 126. Furthermore, in static scenarios, a few frequency channels of the (partial) synchronization data packets 126 may happen to be located in fading holes and thus never be received by the participants. Furthermore, in some regions (e.g. the United States) it may be necessary to unify the occupied frequencies in order to obtain certification (e.g. according to the FCC).

[0336] This problem can be circumvented by transmitting the (partial) synchronization packets 126_1-126_k multiple times on different frequencies. Fig.14Here, the first transmission (e.g. of (partial) synchronization packets 126_1-126_k) occupies frequency channels c0 to c2, and the second transmission (e.g. of (partial) synchronization packets 126_1-126_k) occupies channels c3 to c5. Therefore, frequency channels c6 to c8 may be occupied by further transmissions (e.g. of (partial) synchronization packets 126_1-126_k).

[0337] In detail, Fig.14 The occupancy of the frequency band 103 of the communication system 100 in the transmission of a point-to-multipoint data transmission 104 with a plurality of partial payload data packets 128_1-128_i (i=8) according to an embodiment of the present invention and the repeated transmission of partial synchronization data packets 126_1-126_k on different partial frequency ranges 125_1 and 125_2 of the specified frequency range 125 are shown. Fig.14 In , the ordinate describes the frequency (frequency channel) and the abscissa describes the time (time slot).

[0338] In an embodiment, the partial frequency ranges 125_1 and 125_2 may each be smaller than a reception bandwidth of a receiver of the participant 106_1 or a receiver of a participant ( 106_1 - 106_n ) of the communication system 100 .

[0339] In other words, Fig.14 The change of the frequency channels of (part of) the synchronization data packets 126_1 - 126_k is shown.

[0340] Thus, for example, a participant 106_1 that did not detect a (partial) synchronization packet 126_1-126_k in channel c0 to c2 may change channels and look for a (partial) synchronization packet 126_1-126_k there again. If it does not detect anything there, it may change the frequency channel again, etc.

[0341] This makes it possible for participants (eg, nodes) that face continuous outages or are in fading holes on some parts of the channel to still participate in multicast (eg, point-to-multipoint data transmission) 124 .

[0342] For illustration purposes, in an embodiment, an increasing order of frequency channels for successive partial synchronization packets 126_1-126_k is selected. However, this is not mandatory, i.e. another sequence of frequency channels (e.g., transmit n: c0, c1, c2, transmit n+1: c10, c11, c12, transmit n+2: c5, c6, c7, etc.) may be determined in other embodiments.

[0343] In an embodiment, the frequency channels used for transmitting (partial) synchronization data packets 126_1-126_k may vary over time. In this case, there may be a temporal periodicity of the entire pattern of repeating the channel sequence.

[0344] In order to maximize the transmission reliability, the (partial) synchronization data packets 126_1-126_k of different time slots can be derived from the same synchronization information so that any combination of the (partial) synchronization data packets 126_1-126_k can be used for reconstructing the data. If this is the case, then the receiver (e.g. of the participant 106_1) cannot unambiguously determine which frequency offset is present in the case of the same cluster across time slots, because it cannot determine whether the partial synchronization data packet 126_1-126_k belongs to transmission n or n+1 if the frequency offset is greater than the distance of the cluster.

[0345] In this case, the term cluster refers to the transmission of the partial synchronization packets 126_1-126_k. For example, the first transmission of the partial synchronization packets 126_1-126_k (k=3) can be referred to as the first cluster 130_1, and the second transmission of the partial synchronization packets 126_1-126_k (k=3) can be referred to as the second cluster 130_2 (see Fig.14 ).

[0346] In an embodiment, the clusters 130_1 - 130_2 may be separated from each other in frequency so that it is not possible to accidentally synchronize to a cluster that is moving within the frequency range due to frequency offset.

[0347] Within a cluster 130_1-130_2, it may be advantageous to know exactly which of the (partial) synchronization packets 126_1-126_k have been received. For example, in the case of a 3-segment cluster c0+c1+c2, if one of the outer two (partial) synchronization packets 126_1-126_k is corrupted, i.e. c0 or c2, the participant (e.g. node) 106_1 may be able to successfully synchronize and decode due to error protection, but will not know whether c0+c1 or c1+c2 was received.

[0348] This ambiguity no longer occurs if the frequency channels cX and cX+1 are spaced far enough apart from one another that, despite the frequency offset, it is possible to unambiguously determine on which cX a (partial) synchronization data packet has been sent.

[0349] In an embodiment, frequency channels within clusters 130_1 - 130_2 may be separated from each other in frequency such that adjacent channels do not overlap, even in the case of frequency offset.

[0350] Another solution is to design the clusters 130_1-130_2 so that the frequency hopping pattern within the cluster is unambiguous. That is, it is not like Fig.14 The step-wise approach shown, but rather the sequence c0+c2+c1, unambiguously determines which (partial) synchronization data packet 126_1-126_k has been received in the event of successful detection of at least two (partial) synchronization data packets 126_1-126_k.

[0351] In an embodiment, the clusters 130_1-130_2 of (partial) synchronization data packets 126_1-126_k may be selected such that the (partial) synchronization data packets 126_1-126_k within a cluster do not have repeated identical intervals in time and / or frequency.

[0352] A further possibility is to identify the frequency position of the clusters 130_1 - 130_2 based on the distance to the payload data packets 128 or partial payload data packets 128_1 - 128_i of the point-to-multipoint data transmission 124 .

[0353] In an embodiment, the clusters 130_1 - 130_2 may have such a temporal distance that they may be unambiguously assigned by the participant 106_1 .

[0354] 2.6 Repeated transmission of (partial) synchronization packets before the payload packets in point-to-multipoint data transmission Staggered Clusters

[0355] According to Section 2.4, if the partial synchronization data packets 126_1-126_k are transmitted repeatedly, it is possible to stagger at least two transmissions in time. For double transmission in the case of a subdivision (of the synchronization data packet 126, for example) into three partial synchronization data packets 126_1-126_k (k=3), this can be done in Fig.15 Seen in.

[0356] In detail, Fig.15 The occupancy of the frequency band 103 of the communication system 100 in the transmission of a point-to-multipoint data transmission 104 with repeated transmissions of a plurality of partial payload data packets 128_1-128_i (i=8) and partial synchronization data packets 126_1-126_k (k=3) is shown according to an embodiment of the present invention, wherein the repeated transmissions of the partial synchronization data packets 126_1-126_k (k=3) are interleaved. Fig.15 In , the ordinate describes the frequency (frequency channel) and the abscissa describes the time (time slot). In other words, Fig.15 The time interleaving of two transmissions of partial synchronization data packets 126_1-126_k (k=3) is shown.

[0357] The advantage of this time staggering is interference robustness, since there is a larger time interval between adjacent frequency channels. As for the synchronization characteristics of the participant 106_1, there is no change, except that there is a higher delay in the reception of the partial synchronization packets 126_1-126_k. However, this is not a problem, because after receiving the partial synchronization packets 126_1-126_k, the participant 106_1 must wait anyway until it can receive the payload packet 128, or a plurality of partial payload packets 128_1-128_i of the point-to-multipoint data transmission 124.

[0358] Since the distance between the last synchronization data packet 126_3 and the start of the first partial payload data packet 128_1 of the point-to-multipoint data transmission 124 varies from cluster 130_1 to cluster 130_2, this distance (i.e., the time start of the first partial payload data packet 128_1 and the point-to-multipoint data transmission 124) can be known in advance to the participant 106_1 or can be appropriately signaled.

[0359] In an embodiment, in case of repeated transmission of partial synchronization packets 126_1-126_k (eg before a (partial) payload packet 128 of a point-to-multipoint data transmission 124), the repetitions of the partial synchronization packets 126_1-126_k may be interleaved.

[0360] In case of multiple repetitions, all transmissions (eg, of partial synchronization packets 126_1 - 126_k) may be interleaved with each other, wherein between transmitted partial synchronization packets 126_1 - 126_k there is a pause corresponding to the number of repetitions.

[0361] exist Fig.15 In the example of FIG. 1 , a single repetition (e.g., of partial synchronization packets 126_1-126_k) is used, so that between each of the partial synchronization packets 126_1-126_k of the first transmission r0 there is a pause of exactly one hop, i.e., the duration of the partial synchronization packet. In the case of a double repetition (e.g., of partial synchronization packets 126_1-126_k), the pause would be two hops (e.g., of the partial synchronization packets), and so on.

[0362] Emission r1 starts at time step t1 with the same pattern (corresponding to the cluster). By choosing equidistant distances, it is ensured that there is no temporal overlap between repetitions.

[0363] When two repetitions are used, the second repetition will start at time slot t2.

[0364] In an embodiment, a basic cluster (eg, a basic frequency hopping pattern) that is used in all repeated transmissions (eg, of the partial synchronization packets 126_1 - 126_k) may be used.

[0365] In an embodiment, the time interval between the partial synchronization packets 126_1 - 126_k within the cluster may correspond to the number of repetitions (eg, of the partial synchronization packets 126_1 - 126_k).

[0366] 2.7 Virtual Cyclic Continuation of Sequences in the Case of Partial Reception with Cyclic Dependencies

[0367] If the participant (eg, terminal node) 106_1 does not know the exact time position of the partial synchronization packets 126_1-126_k, it may receive a sequence at least twice as long to obtain it completely at once. It is assumed that the base station 104 repeats the partial synchronization packets 126_1-126_k continuously (eg, without time pauses).

[0368] In order to reduce the reception time exactly to the length of the partial synchronization data packets 126_1-126_k, the receiver (e.g. of the participant 106_1) can cyclically associate the partial synchronization data packets and thus receive the sequence regardless of the position of the received data. For this purpose, the transmission (e.g. of the partial synchronization data packets 126_1-126_k) should occur consistently over the entire length, e.g. with an SDR front end (SDR=software defined radio).

[0369] Fig.16 The diagram shows the occupancy of a given frequency range 125 and the reception window 129 of the receiver of the participant 106_1 for receiving the partial synchronization data packets 126_1-126_k (k=3) according to an exemplary embodiment of the present invention in the case of periodic transmission of partial synchronization data packets 126_1-126_k (k=3). Fig.16 In the example, the ordinate describes frequency and the abscissa describes time. In other words, Fig.16 The cyclic reception of a synchronization sequence, such as partial synchronization data packets 126_1 - 126_k (k=3), is shown.

[0370] In an embodiment, a receiver (eg, of participant 106_1 ) may use the periodicity of the partial synchronization packets 126_1 - 126_k (k=3) to perform a cyclic correlation.

[0371] For more robust reception, cyclic correlation may be performed only on completely received partial synchronization packets. In this case, for example, the receive window 129 is extended to the length of four partial synchronization packets. Thus, three partial synchronization packets are always completely received and can be combined into a sequence. The correlation may occur in the time domain or the frequency domain (e.g., via FFT).

[0372] Fig.17The diagram shows the occupancy of a given frequency range 125 and a reception window 129 of a receiver of a participant 106_1 for receiving partial synchronization data packets 126_1-126_k (k=3) according to an exemplary embodiment of the present invention, wherein the length of the reception window 129 corresponds to the length of four partial synchronization data packets. Fig.17 In the example, the ordinate describes frequency and the abscissa describes time. In other words, Fig.17 The cyclic reception of a synchronization sequence (eg, partial synchronization packets 126_1 - 126_k (k=3)) at the partial synchronization packet level is shown.

[0373] In an embodiment, a receiver (eg, of participant 106_1 ) may use the periodicity of the partial sync packets 126_1 - 126_k for cyclic correlation on the partial sync packet level.

[0374] Furthermore, combinations of the embodiments of Sections 2.4, 2.5 and 2.6 are possible, such as Fig.18 as shown in .

[0375] In detail, Fig.18 The schematic diagram shows the occupation of a specified frequency range 125 in the repeated transmission of partial synchronization data packets 126_1-126_k (k=3) according to an embodiment of the invention and two reception windows 129_1 and 129_2 of a receiver of a participant 106_1 for receiving partial synchronization data packets 126_1-126_k (k=3), wherein the repeated transmissions of the partial synchronization data packets 126_1-126_k (k=3) are versions of each other that are offset in time and frequency. Fig.18 In the example, the ordinate describes frequency and the abscissa describes time. In other words, Fig.18 A cyclic reception of a sequence of partial synchronization packet levels (eg, partial synchronization packets 126_1 - 126_k) on different frequencies is shown.

[0376] 2.8 Different Bitrates

[0377] In order to ensure the highest possible transmission reliability, it is advantageous to provide the transmitted data with an error protection code. Depending on the requirements of the system (communication system) 100, it may be necessary to use more (partial) synchronization packets, so that the threshold of a synchronization packet (e.g. a partial synchronization packet) is at least below the threshold at which it may be decoded.

[0378] For example, if a very low rate error protection (e.g., a convolutional code with a code rate of 1 / 4) is used in the payload data packet 128 of the point-to-multipoint data transmission 124, this packet may be decoded up to, for example, an SNR of 0 dB. Now, if very few (partial) synchronization data packets 126_1-126_k are transmitted (e.g., high rate error protection (e.g., a convolutional code with a code rate of 1 / 2)), the (partial) synchronization data packets 126_1-126_n may be successfully synchronized only when the SNR reaches +3 dB. In this case, the increased error protection in the payload data packet 128 of the point-to-multipoint data transmission 124 will waste energy in the transmission of the payload data packet 128 of the point-to-multipoint data transmission 124, because without the synchronization of the (partial) synchronization data packets 126_1-126_k, the payload data packet 128 of the point-to-multipoint data transmission 124 may not be received because its position and / or hopping pattern is unknown.

[0379] Thus, the number of (partial) synchronization data packets 126_1 - 126_k may be adapted to the error protection code of the payload data packets 128 of the point-to-multipoint data transmission 124 to be used.

[0380] In an embodiment, the number of (partial) synchronization packets 126_1 - 126_k may be adapted to the error protection used in the payload packets 128 of the point-to-multipoint data transmission 124 .

[0381] Since the information in (part of) the synchronization data packet should also be decodable under the same threshold as the payload data packet 128 of the point-to-multipoint data transmission 124, it may be advantageous to provide the synchronization data packet 126 with similar error protection code as the payload data packet 128 of the point-to-multipoint data transmission 124.

[0382] In an embodiment, the payload data packets 128 and the synchronization data packets 126 of the point-to-multipoint data transmission 124 may use the same error protection code.

[0383] In an embodiment, the payload data packets 128 and the synchronization data packets 126 of the point-to-multipoint data transmission 124 may use error protection codes with comparable performance.

[0384] If the synchronization data packet 126 is very short, it may be useful to use a simple repetition code instead of a common error protection code (such as a convolutional code) and pack all the information into each individual partial synchronization data packet 126_1-126_k.

[0385] In an embodiment, all partial sync packets 126_1 - 126_k may be of the same sign.

[0386] 3. Further Embodiments

[0387] The embodiments described below may be implemented or applied alone or in combination with the above embodiments.

[0388] Fig.19 A flow chart of a method 240 for operating an uncoordinated transmission participant of a communication system according to an embodiment of the present invention is shown. The method 240 includes a step 242 of receiving a synchronization data packet of a point-to-multipoint data transmission of a base station of the communication system, wherein the synchronization data packet is transmitted within a frequency range of a frequency band specified or known to the participant. In addition, the method 240 includes a step 244 of receiving a payload data packet of the point-to-multipoint data transmission referenced based on the synchronization data packet [e.g., synchronously; e.g., at a specified time and / or frequency interval] transmitted at a time and / or frequency to the synchronization data packet.

[0389] Fig. 20 A flow chart of a method 250 for operating a base station of a communication system according to an embodiment of the present invention is shown. The method 250 comprises a step 252 of transmitting a point-to-multipoint data transmission to a plurality of non-coordinated transmission participants of the communication system, wherein the point-to-multipoint data transmission comprises a synchronization data packet and a payload data packet which is referenced in time and / or frequency [e.g. synchronized: e.g. at a specified time and / or frequency interval and / or time hopping pattern and / or frequency hopping pattern] to the synchronization data packet, wherein the synchronization data packet is transmitted within a frequency range of a frequency band of the communication system specified or known to the participants.

[0390] Embodiments of the present invention are used in a communication system for radio transmission of data from a participant [terminal device] to a base station or from one or more base stations to a participant [e.g., terminal device]. For example, the communication system may be a personal area network (PAN) or a low power wide area network (LPWAN), wherein the participant (e.g., terminal device) may be, for example, a battery-powered sensor (sensor node).

[0391] Exemplary embodiments of the present invention are directed to applications in which a message (eg a data packet) is transmitted to a plurality of participants in the form of a plurality of partial data packets (multicast) by means of a so-called telegram splitting method (Telegram Splitting Multiple Access, TSMA).

[0392] Embodiments of the invention relate to a system (communication system) for digital transmission of data via a radio transmission system. The transmitted data are usually transmitted in several partial frequency channels of the total available bandwidth.

[0393] Embodiments of the invention may be used in so-called uncoordinated networks, in which radio participants transmit data in an uncoordinated manner (without prior allocation of radio resources).

[0394] For example, embodiments of the present invention may be used in a communication system as defined in the ETSI TS 103 357 standard [4].

[0395] Embodiments provide participants [e.g., terminal points] of a communication system, [wherein the communication system communicates wirelessly in a frequency band [e.g., an ISM band] used by multiple [e.g., mutually non-coordinated] communication systems], wherein the participants are configured to send data uncoordinatedly relative to other participants and / or base stations of the communication system, wherein the participants are configured to receive, in time synchronization with uplink data transmissions sent to a base station of the communication system, downlink data transmissions from the base station, wherein the downlink data transmissions include signaling information, wherein the participants are configured to receive point-to-multipoint data transmissions [e.g., [multicast data transmissions]] from the base station based on the signaling information.

[0396] In an embodiment, the signaling information may include information on a time point of point-to-multipoint data transmission.

[0397] For example, the information about the time point can be an absolute time point, a relative time point [such as a defined time span between a downlink data transmission and a point-to-multipoint data transmission], or information from which an absolute or relative time point can be derived, such as the number of clock cycles of a participant oscillator.

[0398] In an embodiment, the signaling information may further include information about a frequency channel [eg, a frequency band used by the communication system] for point-to-multipoint data transmission.

[0399] For example, the information on the frequency channel may be an absolute frequency channel or a relative frequency channel [eg, a distance between a frequency channel for downlink data transmission and a frequency channel for point-to-multipoint data transmission].

[0400] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the signaling information further includes information about the time hopping and / or frequency hopping pattern.

[0401] For example, point-to-multipoint data transmission may be data transmission based on telegram splitting. In data transmission based on telegram splitting, data to be transmitted [e.g., [encoded] physical layer payload data] is divided into a plurality of sub-data packets, so that each of the plurality of sub-data packets only includes a portion of the data to be transmitted, wherein the plurality of sub-data packets are not transmitted continuously but are distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern.

[0402] In an embodiment, information about the time point of the point-to-multipoint data transmission may include a defined [e.g. expected or intentional] inaccuracy that is at least large enough so that receiving the point-to-multipoint data transmission requires the recipient to synchronize to the point-to-multipoint data transmission, wherein the participant is configured to perform synchronization to the point-to-multipoint data transmission in order to receive the point-to-multipoint data transmission.

[0403] In an embodiment, the defined inaccuracy may be in the range of 1 to 10,000 symbol durations.

[0404] In an embodiment, the defined inaccuracy may be subject to non-linear scaling [eg logarithmic scaling] as a function of the time interval of the point-to-multipoint data transmissions, so that the inaccuracy is larger as the interval of the point-to-multipoint data transmissions increases.

[0405] In an embodiment, the downlink data transmission may further include clock generator correction information [e.g., quartz offset in ppm for timers and frequency generators] for correcting clock deviation of the participant's clock generator, wherein the participant is configured to correct the clock deviation of the clock generator based on the clock generator correction information.

[0406] In an embodiment, the uplink data transmission may be a first uplink data transmission, wherein the downlink data transmission may be a first downlink data transmission, wherein the signaling information is first signaling information, wherein the first signaling information signals a period of time or a time point [e.g., a rough time point] for a second uplink data transmission [e.g., after the first uplink data transmission], wherein the participant is configured to send the second uplink data transmission to the base station within the signaled time period, and to receive the second downlink data transmission from the base station in time synchronization with the second uplink data transmission, wherein the second downlink data transmission includes second signaling information, and wherein the participant is configured to receive point-to-multipoint data transmission [e.g., multicast data transmission] based on the second signaling information.

[0407] In an embodiment, the second signaling information may include information about a time point of point-to-multipoint data transmission.

[0408] In an embodiment, the second signaling information may further include information on a frequency channel for point-to-multipoint data transmission [eg, of a frequency band used by the communication system].

[0409] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the second signaling information further includes information about the time hopping and / or frequency hopping pattern.

[0410] In an embodiment, if the second downlink data transmission cannot be successfully received [for example, if the second downlink data transmission does not occur or is interrupted], the participant can be configured to send a third uplink data transmission to the base station and receive a third downlink data transmission from the base station that is synchronized with the third uplink data transmission time, wherein the third downlink data transmission includes third signaling information, and wherein the participant is configured to receive point-to-multipoint data transmission [for example, multicast data transmission] based on the third signaling information.

[0411] In an embodiment, the first downlink data transmission or the second downlink data transmission may further include clock generator correction information describing a clock deviation of a participant's clock generator relative to a reference clock, wherein the participant is configured to receive point-to-multipoint data transmission by using the clock generator correction information [e.g., correcting the clock deviation of the clock generator based on the clock generator correction information to receive the point-to-multipoint data transmission].

[0412] In an embodiment, the uplink data transmission may be a first uplink data transmission, wherein the downlink data transmission is a first downlink data transmission, wherein the signaling information is first signaling information, wherein the first signaling information comprises information about a coarse time point of the point-to-multipoint data transmission, [e.g. wherein the information about the coarse time point of the point-to-multipoint data transmission is too inaccurate for reception of the point-to-multipoint data transmission], wherein the participant is configured to send a fourth uplink data transmission to the base station before the coarse time point of the point-to-multipoint data transmission, and to receive a fourth downlink data transmission from the base station that is time-synchronized with the fourth uplink data transmission, wherein the fourth downlink data transmission comprises fourth signaling information, and wherein the participant is configured to receive the point-to-multipoint data transmission [e.g., multicast data transmission] based on the fourth signaling information.

[0413] In an embodiment, the fourth signaling information may include information about a time point of point-to-multipoint data transmission.

[0414] In an embodiment, the fourth signaling information may further include information on a frequency channel for point-to-multipoint data transmission [eg, a frequency band used by the communication system].

[0415] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the fourth signaling information may further include information about the time hopping and / or frequency hopping pattern.

[0416] In an embodiment, the first downlink data transmission or the fourth downlink data transmission may further include clock generator correction information for correcting a clock deviation of a clock generator of the participant, wherein the participant is configured to correct the clock deviation of the clock generator based on the clock generator correction information.

[0417] In an embodiment, the signaling information may be first signaling information, wherein the first signaling information includes information about a time point of a support beacon, wherein the participant is configured to receive the support beacon based on the first signaling information, wherein the support beacon includes fifth signaling information, wherein the participant is configured to receive point-to-multipoint data transmission [e.g., multicast data transmission] based on the fifth signaling information.

[0418] In an embodiment, the first signaling information may further include information about a frequency channel [eg, the frequency of a frequency band used by the communication system] or a frequency offset supporting the beacon.

[0419] In an embodiment, the fifth signaling information may include information on a time point of point-to-multipoint data transmission.

[0420] In an embodiment, the fifth signaling information may further include information on a frequency channel for point-to-multipoint data transmission [eg, of a frequency band used by the communication system].

[0421] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the fifth signaling information further includes information about the time hopping and / or frequency hopping pattern.

[0422] In an embodiment, the downlink data transmission or supporting beacon may further include clock generator correction information for correcting the clock deviation of the clock generator of the participant, wherein the participant is configured to correct the clock deviation of the clock generator based on the clock generator correction information.

[0423] In an embodiment, participants may be configured to asynchronously send data to other participants and / or a base station of the communication system.

[0424] For example, a participant may be configured to send uplink data asynchronously to a base station.

[0425] In an embodiment, a participant may be configured to send uplink data transmissions to a base station at random or pseudo-random time points.

[0426] In an embodiment, the uplink data transmission may include a plurality of sub-data packets transmitted distributed in time and / or frequency according to a time and / or frequency hopping pattern.

[0427] For example, uplink data transmission may be data transmission based on telegram splitting. In data transmission based on telegram splitting, data to be transmitted [e.g., (encoded) physical layer payload data] is divided into a plurality of sub-data packets, so that each of the plurality of sub-data packets only includes a portion of the data to be transmitted, wherein the plurality of sub-data packets are not transmitted continuously, but are distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern.

[0428] In an embodiment, a downlink data transmission may include a plurality of sub-data packets transmitted distributed in time and / or frequency according to a time and / or frequency hopping pattern.

[0429] For example, downlink data transmission may be data transmission based on telegram splitting. In data transmission based on telegram splitting, data to be transmitted [e.g., (encoded) physical layer payload data] is divided into a plurality of sub-data packets, so that each of the plurality of sub-data packets only includes a portion of the data to be transmitted, wherein the plurality of sub-data packets are not transmitted continuously, but are distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern.

[0430] In an embodiment, an actor may be a sensor node or an actuator node.

[0431] In an embodiment, the participant may be battery powered.

[0432] In an embodiment, a participant may include an energy harvesting element for generating electrical energy.

[0433] A further embodiment provides a base station of a communication system [wherein the communication system performs wireless communications [e.g., an ISM band] in a frequency band used by a plurality of [e.g., mutually uncoordinated] communication systems], wherein the base station is configured to receive an uplink data transmission from a participant of the communication system, wherein the uplink data transmission is uncoordinated, wherein the base station is configured to send a downlink data transmission to the participant in time synchronization with the received uplink data transmission of the participant, wherein the downlink data transmission comprises signaling information, wherein the signaling information signals a subsequent point-to-multipoint data transmission or a further data transmission preceding the point-to-multipoint data transmission, wherein the base station is configured to send the point-to-multipoint data transmission [e.g., to a plurality of participants of the communication system, wherein the participant is part of a plurality of participants] in accordance with the signaling information.

[0434] In an embodiment, the signaling information may include information on a time point of point-to-multipoint data transmission.

[0435] For example, the information about the time point can be an absolute time point, a relative time point [such as a defined time span between a downlink data transmission and a point-to-multipoint data transmission], or information from which an absolute or relative time point can be derived, such as the number of clock cycles of a participant oscillator.

[0436] In an embodiment, the signaling information may further include information about a frequency channel for point-to-multipoint data transmission [eg, of a frequency band used by the communication system].

[0437] For example, the information on the frequency channel may be an absolute frequency channel or a relative frequency channel [eg, a distance between a frequency channel for downlink data transmission and a frequency channel for point-to-multipoint data transmission].

[0438] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the signaling information further includes information about the time hopping and / or frequency hopping pattern.

[0439] For example, point-to-multipoint data transmission may be data transmission based on telegram splitting. In data transmission based on telegram splitting, data to be transmitted [e.g., [encoded] physical layer payload data] is divided into a plurality of sub-data packets, so that each of the plurality of sub-data packets only includes a portion of the data to be transmitted, wherein the plurality of sub-data packets are not transmitted continuously but are distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern.

[0440] In an embodiment, the information about the timing of the point-to-multipoint data transmission may include a defined [eg expected or intentional] at least sufficiently large inaccuracy such that receiving the point-to-multipoint data transmission requires the receiver to synchronize to the point-to-multipoint data transmission.

[0441] In an embodiment, the defined inaccuracy may be in the range of 1 to 10,000 symbol durations.

[0442] In an embodiment, the defined inaccuracy may be non-linearly scaled as a function of the time interval to the point-to-multipoint data transmission, such that the inaccuracy is larger as the interval to the point-to-multipoint data transmission increases.

[0443] In an embodiment, the base station may be configured to determine a clock bias of a participant's clock generator based on the participant's uplink data transmission, wherein the base station is configured to provide clock generator correction information to the downlink data transmission for correcting the clock bias of the participant's clock generator.

[0444] In an embodiment, the base station can be configured to determine the clock deviation of the participant's clock generator based on the uplink data transmission to the participant, wherein the signaling information includes information about the time point of the point-to-multipoint data transmission taking into account the clock deviation on the participant's clock generator [e.g., so that the clock deviation of the clock generator is compensated], and / or wherein the signaling information includes information about the frequency channel of the point-to-multipoint data transmission taking into account the clock deviation of the participant's clock generator [e.g., so that the clock deviation of the clock generator is compensated].

[0445] In an embodiment, the uplink data transmission may be a first uplink data transmission, wherein the downlink data transmission is a first downlink data transmission, wherein the signaling information is first signaling information, wherein the first signaling information signals a period of time or a point in time [e.g. a rough point in time] for a second uplink data transmission [e.g. after the first uplink data transmission], wherein the base station is configured to receive a second uplink data transmission from a participant within the signaled time period, and to send a second downlink data transmission to the participant in time synchronization with the second uplink data transmission, wherein the second downlink data transmission comprises second signaling information, wherein the second signaling information signals a subsequent point-to-multipoint data transmission [e.g. wherein the second uplink data transmission and / or the second downlink data transmission is a further data transmission], wherein the base station is configured to send the point-to-multipoint data transmission according to the second signaling information [e.g. to multiple participants of the communication system, wherein the participant is part of multiple participants].

[0446] In an embodiment, the second signaling information may include information about a time point of point-to-multipoint data transmission.

[0447] In an embodiment, the second signaling information may further include information on a frequency channel for point-to-multipoint data transmission [eg, of a frequency band used by the communication system].

[0448] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the second signaling information further includes information about the time hopping and / or frequency hopping pattern.

[0449] In an embodiment, the base station may be configured to determine a clock deviation of a participant's clock generator based on the participant's second uplink data transmission, wherein the base station is configured to provide correction information for the clock generator to correct the clock deviation of the participant's clock generator for the second downlink data transmission.

[0450] In an embodiment, the base station can be configured to determine the clock deviation of the participant's clock generator based on the participant's first or second uplink data transmission, wherein the second signaling information includes information about the time point of the point-to-multipoint data transmission taking into account the clock deviation of the participant's clock generator [e.g., thereby compensating for the clock deviation of the clock generator].

[0451] In an embodiment, the uplink data transmission may be a first uplink data transmission, wherein the downlink data transmission is a first downlink data transmission, wherein the signaling information is first signaling information, wherein the first signaling information comprises information about a coarse point in time of the point-to-multipoint data transmission [e.g. wherein the information about the coarse point in time of the point-to-multipoint data transmission is too inaccurate for reception of the point-to-multipoint data transmission], wherein the base station is configured to receive a fourth uplink data transmission from the participant before the coarse point in time of the point-to-multipoint data transmission, and to send a fourth downlink data transmission to the participant in time synchronization with the fourth uplink data transmission, wherein the fourth downlink data transmission comprises fourth signaling information, wherein the fourth signaling information signals a subsequent point-to-multipoint data transmission, [e.g. wherein the fourth uplink data transmission and / or the fourth downlink data transmission is a further data transmission], wherein the base station is configured to send the point-to-multipoint data transmission according to the fourth signaling information [e.g. to multiple participants of the communication system, wherein the participant is part of multiple participants].

[0452] In an embodiment, the fourth signaling information may include information about a time point of point-to-multipoint data transmission.

[0453] In an embodiment, the fourth signaling information may further include information on a frequency channel for point-to-multipoint data transmission [eg, a frequency band used by the communication system].

[0454] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the fourth signaling information may further include information about the time hopping and / or frequency hopping pattern.

[0455] In an embodiment, the base station may be configured to determine a clock deviation of a participant's clock generator based on the participant's fourth uplink data transmission, wherein the base station is configured to provide clock generator correction information to the fourth downlink data transmission for correcting the clock deviation of the participant's clock generator.

[0456] In an embodiment, the base station can be configured to determine the clock deviation of the participant's clock generator based on the participant's fourth uplink data transmission, wherein the fourth signaling information includes information about the time point of the point-to-multipoint data transmission taking into account the clock deviation on the participant's clock generator [for example, so that the clock deviation of the clock generator is compensated], and / or wherein the fourth signaling information includes information about the frequency channel of the point-to-multipoint data transmission taking into account the clock deviation of the participant's clock generator [for example, so that the clock deviation of the clock generator is compensated].

[0457] In an embodiment, the signaling information may be first signaling information, wherein the first signaling information comprises information about a point in time of supporting a beacon, wherein the base station is configured to support the beacon based on sending of the first signaling information [e.g. sending to a plurality of participants of the communication system, wherein the participant is part of a plurality of participants], wherein the supporting beacon comprises fifth signaling information, wherein the fifth signaling information signals a subsequent point-to-multipoint data transmission [e.g. wherein the supporting beacon is a further data transmission].

[0458] In an embodiment, the first signaling information may further include information on a frequency channel supporting the beacon [eg, of a frequency band used by the communication system].

[0459] In an embodiment, the fifth signaling information may include information on a time point of point-to-multipoint data transmission.

[0460] In an embodiment, the fifth signaling information may further include information on a frequency channel for point-to-multipoint data transmission [eg, a frequency band used by the communication system].

[0461] In an embodiment, the point-to-multipoint data transmission may include multiple sub-data packets transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the fifth signaling information further includes information about the time hopping and / or frequency hopping pattern.

[0462] In an embodiment, the base station may be configured to determine a clock bias of a participant's clock generator based on the participant's uplink data transmission, wherein the base station is configured to provide clock generator correction information to a downlink data transmission or a supporting beacon for correcting the clock bias of the participant's clock generator.

[0463] In an embodiment, the base station can be configured to determine the clock deviation of the clock generator of the participant based on the uplink data transmission of the participant, wherein the information about the time point of the point-to-multipoint data transmission included in the fifth signaling information takes into account the clock deviation of the clock generator of the participant [e.g. so as to compensate for the clock deviation of the clock generator].

[0464] A further embodiment provides a method for operating a participant of a communication system. The method comprises the step of sending an uplink data transmission to a base station of the communication system, wherein the uplink data transmission is uncoordinated. Furthermore, the method comprises the step of receiving a downlink data transmission from the base station that is synchronized in time with the uplink data transmission, wherein the downlink data transmission comprises signaling information. Furthermore, the method comprises the step of receiving a point-to-multipoint data transmission [e.g., a multicast data transmission] from the base station based on the signaling information.

[0465] A further embodiment provides a method for operating a base station of a communication system. The method comprises the step of receiving an uplink data transmission from a participant of the communication system, wherein the uplink data transmission is uncoordinated. Furthermore, the method comprises the step of sending a downlink data transmission to the participant that is synchronized in time with the uplink data transmission, wherein the downlink data transmission comprises signaling information, wherein the signaling information signals a subsequent point-to-multipoint data transmission or a further data transmission preceding the point-to-multipoint data transmission. Furthermore, the method comprises sending the point-to-multipoint data transmission in accordance with the signaling information [e.g. to a plurality of participants of the communication system, wherein the participant is part of a plurality of participants].

[0466] Although certain aspects have been described in the context of a device, it should be understood that the aspects also represent a description of the corresponding method, and therefore the blocks or structural components of the device should also be understood as corresponding method steps or as features of method steps. Similarly, aspects that have been described in the context of method steps or as method steps also represent descriptions of corresponding blocks or details or features of corresponding devices. Some or all method steps can be performed when using hardware devices, such as microprocessors, programmable computers, or electronic circuits. In some embodiments, some or several of the most important method steps can be performed by such devices.

[0467] Depending on the specific implementation requirements, embodiments of the present invention can be implemented in hardware or software. It can be implemented using a digital storage medium, such as a floppy disk, DVD, Blu-ray disc, CD, ROM, PROM, EPROM, EEPROM or flash memory, hard disk or any other magnetic or optical storage with electronically readable control signals stored thereon, which can cooperate with a programmable computer system to perform the corresponding method. This is why the digital storage medium can be computer readable.

[0468] Therefore, some embodiments according to the invention comprise a data carrier comprising electronically readable control signals capable of cooperating with a programmable computer system, such that any of the methods described herein is performed.

[0469] Generally, embodiments of the present invention can be implemented as a computer program product with a program code, which is effective to perform any method when the computer program product runs on a computer.

[0470] For example, the program code can also be stored on a machine-readable carrier.

[0471] Other embodiments comprise the computer program for performing any of the methods described herein, stored on a machine readable carrier.

[0472] In other words, an embodiment of the inventive method is, therefore, a computer program having a program code for performing any of the methods described herein, when the computer program runs on a computer.

[0473] Therefore, a further embodiment of the inventive method is a data carrier (or a digital storage medium or a computer-readable medium), on which the computer program for executing any of the methods described herein is recorded. The data carrier, the digital storage medium or the recorded medium is generally tangible or non-volatile.

[0474] Therefore, a further embodiment of the inventive method is a data stream or a sequence of signals representing the computer program for performing any of the methods described herein.The data stream or the sequence of signals may be configured to be sent, for example, via a data communication link, for example via the Internet.

[0475] Further embodiments comprise a processing unit, for example a computer or a programmable logic device, configured or adapted to perform any of the methods described herein.

[0476] A further embodiment comprises a computer on which is installed the computer program for performing any of the methods described herein.

[0477] A further embodiment according to the invention comprises a device or system configured to send a computer program for performing at least one of the methods described herein to a receiver. For example, the sending may be electronic or optical. For example, the receiver may be a computer, a mobile device, a memory device, or the like. For example, the device or system may comprise a file server for sending the computer program to the receiver.

[0478] In some embodiments, a programmable logic device (e.g., a field programmable gate array, FPGA) may be used to perform some or all of the functions of the methods described herein. In some embodiments, a field programmable gate array may cooperate with a microprocessor to perform any of the methods described herein. Typically, in some embodiments, these methods are performed by any hardware device. The hardware device may be any general-purpose hardware, such as a computer processor (CPU), or may be hardware specific to the method, such as an ASIC.

[0479] For example, the apparatus described herein may be implemented using a hardware device, or may be implemented using a computer, or may be implemented using a combination of a hardware device and a computer.

[0480] The apparatus described herein or any component of an apparatus described herein may be implemented at least partly in hardware and / or software (computer program).

[0481] For example, the methods described herein may be implemented using a hardware device, or using a computer, or using a combination of a hardware device and a computer.

[0482] The methods described herein or any component of the methods described herein may be implemented at least in part by execution and / or software (computer program).

[0483] The above embodiments represent only an illustration of the principles of the present invention. It should be understood that other persons skilled in the art will appreciate modifications and variations of the arrangements and details described herein. This is why the present invention is intended to be limited only by the scope of the appended claims rather than by the specific details presented herein through the description and discussion of the embodiments.

[0484] References

[0485] [1] G.Kilian, M.Breiling, HHPetkov, H.Lieske, F.Beer, J.Robert, andA.Heuberger, "Increasing Transmission Reliability for Telemetry Systems Using Telegram Splitting," IEEE Transactions on Communications, vol.63, no.3, pp.949–961, Mar.2015.

[0486] [2]DE 10 2011 082 098 B1

[0487] [3]DE 10 2017 206 236 A1

[0488] [4]ETSI TS 103 357 Standard v1.1.1

[0489] [5]G.Kilian,H.Petkov,R.Psiuk,H.Lieske,F.Beer,J.Robert,andA.Heuberger,“Improved coverage for low-power telemetry systems using telegramsplitting,”in Proceedings of 2013 European Conference on Smart Objects,Systems and Technologies(SmartSysTech),2013

Claims

1. Participants (106_1) of the communication system (100), including: A transmitter (108_1) configured to asynchronously transmit data to a base station (104) of the communication system (100), and The receiver (112_1) is configured as: Receiving a synchronization data packet (126) of a multicast data transmission (124) of the base station (104) of the communication system (100), wherein the synchronization data packet (126) is transmitted in a frequency range (125) known to the participant (106_1) of a frequency band (103) of the communication system (100), wherein the frequency range known to the participant corresponds at most to a reception bandwidth of a receiver of the participant, wherein the frequency band used by the communication system comprises a bandwidth at least five times greater than the reception bandwidth of the receiver of the participant, and receiving, based on the synchronization data packet (126), a payload data packet (128) of the multicast data transmission (124) that refers to the synchronization data packet (126) in time and / or frequency, wherein the synchronization data packet (126) of the multicast data transmission (124) is transmitted divided into a plurality of partial synchronization data packets (126_1-126_k), wherein each of the plurality of partial synchronization data packets (126_1-126_k) comprises a portion of the synchronization data packet (126), and wherein the plurality of partial synchronization data packets (126_1-126_k) are transmitted distributed in time and / or frequency according to a time hopping and frequency hopping pattern known to the participant (106_1), and The plurality of partially synchronized data packets (126_1-126_k) are received based on the time and frequency hopping pattern known to the participant (106_1), wherein the plurality of partially synchronized data packets (126_1-126_k) are transmitted within the frequency range known to the participant.

2. The participant (106_1) according to claim 1, in, The payload data packet (128) of the multicast data transmission (124) is transmitted divided into a plurality of partial payload data packets (128_1-128_i), wherein each of the plurality of partial payload data packets (128_1-128_i) comprises a portion of the payload data packet (128), and wherein the plurality of partial payload data packets (128_1-128_i) are transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, wherein the synchronization data packet (126) includes information about the time hopping and / or frequency hopping pattern, The receiver (112_1) is configured to receive the plurality of partial payload data packets (128_1-128_i) based on the information about the time hopping and / or frequency hopping pattern.

3. The participant (106_1) according to claim 1, in, The transmitter (108_1) is configured to send an uplink data transmission (120) to the base station (104) of the communication system (100), and wherein the receiver (112_1) is configured to receive a downlink data transmission (122) from the base station (104) in time synchronization with the sent uplink data transmission (120), wherein the downlink data transmission (122) includes signaling information, and The synchronization data packet (126) of the multicast data transmission (124) is received based on the signaling information.

4. The participant (106_1) according to claim 3, in, The signaling information includes information about a time point of transmission of the synchronization data packet (126).

5. The participant (106_1) according to claim 1, in, The synchronization data packet (126) is transmitted multiple times, The first transmission of the synchronization data packet (126) and the second transmission of the synchronization data packet (126) are versions of each other that are offset in time and / or frequency.

6. The participant (106_1) according to claim 3, wherein: The downlink data transmission (122) includes information about the time and / or frequency hopping pattern of the synchronization data packet (126).

7. The participant (106_1) according to claim 1, in, The partial synchronization packets (126_1-126_k) are channel coded such that only a subset of the plurality of partial synchronization packets (126_1-126_k) are required to successfully decode the synchronization packet (126), The receiver (112_1) is configured to receive and decode at least a portion of the plurality of partial synchronization data packets (126_1-126_k) to obtain the synchronization data packet (126).

8. The participant (106_1) according to claim 1, in, The synchronization data packets (126) and the payload data packets (128) of the multicast data transmission (124) are encoded with the same error protection code.

9. The participant (106_1) according to claim 1, in, The participant (106_1) is a sensor node or an actuator node, wherein the participant (106_1) is battery powered, and / or Therein, the participant (106_1) comprises an energy collection element for generating electrical energy.

10. A base station (104) of a communication system (100), comprising a transmitter (118), configured to: sending a multicast data transmission (124) to asynchronously transmitting participants (106_1-106_n) of the communication system (100), wherein the multicast data transmission (124) comprises a synchronization data packet (126) and a payload data packet (128) that references the synchronization data packet (126) in time and / or frequency, wherein the synchronization data packet (126) is transmitted in a frequency range (125) known to the participants (106_1-106_n) of a frequency band (103) of the communication system (100), and The synchronization data packet (126) of the multicast data transmission (124) is divided into a plurality of partial synchronization data packets (126_1-126_k) for transmission, wherein each of the plurality of partial synchronization data packets (126_1-126_k) comprises a portion of the synchronization data packet (126), and wherein the plurality of partial synchronization data packets (126_1-126_k) are transmitted distributed in time and / or frequency according to a time hopping and frequency hopping pattern known to the participant (106_1), in, transmitting the plurality of partial synchronization packets (126_1-126_k) according to the time-hopping and frequency-hopping pattern of the synchronization packet (126) within the frequency range (125) known to the participants (106_1-106_n), wherein the frequency range (125) known to the participants (106_1-106_n) corresponds at most to a reception bandwidth of a receiver of the participants (106_1-106_n), Therein, the frequency band used by the communication system includes a bandwidth at least 5 times larger than the reception bandwidth of the receiver of the participant.

11. The base station (104) according to claim 10, wherein: The transmitter (118) is configured to: transmitting the payload data packet (128) of the multicast data transmission (124) divided into a plurality of partial payload data packets (128_1-128_i), wherein the plurality of partial payload data packets (128_1-128_i) each comprises a portion of the payload data packet (128), and wherein the plurality of partial payload data packets (128_1-128_i) are transmitted distributed in time and / or frequency according to a time hopping and / or frequency hopping pattern, and The synchronization data packet (126) is provided with information regarding the time hopping and / or frequency hopping pattern.

12. The base station (104) of claim 10, further comprising a receiver (114) configured to receive an uplink data transmission (120) from one of the participants (106_1), in, The transmitter (118) is configured to send a downlink data transmission (122) to the participant (106_1) in time synchronization with the uplink data transmission (120), wherein the downlink data transmission (122) includes signaling information, wherein the signaling information signals the synchronization data packet (126).

13. The base station (104) according to claim 12, in, The signaling information includes information about a time point of transmission of the synchronization data packet (126).

14. The base station (104) of claim 13, further comprising a processor configured to: determining a clock deviation of a clock generator of the participant (106_1) based on the uplink data transmission (120), in, The information about the time point or frequency of the multicast data transmission (124) comprised by the signaling information takes into account the clock deviation of the clock of the participant (106_1).

15. The base station (104) according to claim 10, in, The transmitter (118) is configured to transmit the synchronization data packet (126) a plurality of times, The first transmission of the synchronization data packet (126) and the second transmission of the synchronization data packet (126) are versions of each other that are offset in time and / or frequency.

16. The base station (104) of claim 12, wherein: The transmitter (118) is configured to provide information about the time and / or frequency hopping pattern of the synchronization data packet (126) to the downlink data transmission (122).

17. The base station (104) of claim 10, further comprising a processor configured to: The partial synchronization data packets (126_1-126_k) are channel coded such that only a subset of the plurality of partial synchronization data packets (126_1-126_k) are required to successfully decode the synchronization data packet (126).

18. The base station (104) according to claim 10, in, The synchronization data packets (126) and the payload data packets (128) of the multicast data transmission (124) are encoded with the same error protection code.

19. A method for operating an asynchronous sending participant (106_1) of a communication system (100), the method comprising: receiving a synchronization data packet (126) of a multicast data transmission (124) of a base station (104) of the communication system (100), wherein the synchronization data packet (126) is transmitted in a frequency range (125) known to the participant (106_1) of a frequency band (103) of the communication system (100), receiving, based on the synchronization packet, a payload packet (128) of the multicast data transmission (124) that references the synchronization packet (126) in time and / or frequency, wherein the synchronization data packet (126) of the multicast data transmission (124) is divided into a plurality of partial synchronization data packets (126_1-126_k) for transmission, wherein each of the plurality of partial synchronization data packets (126_1-126_k) comprises a portion of the synchronization data packet (126), and wherein the plurality of partial synchronization data packets (126_1-126_k) are transmitted distributed in time and / or frequency according to a time hopping and frequency hopping pattern known to the participant (106_1), wherein the plurality of partially synchronized data packets (126_1-126_k) are received based on the time hopping and frequency hopping patterns known to the participant (106_1), wherein the plurality of partially synchronized data packets (126_1-126_k) are transmitted within the frequency range known to the participants, wherein the frequency range known to the participant corresponds at most to the reception bandwidth of the participant's receiver, Therein, the frequency band used by the communication system includes a bandwidth at least 5 times larger than the reception bandwidth of the receiver of the participant.

20. A method for operating a base station (104) of a communication system (100), the method comprising: sending a multicast data transmission (124) to a plurality of asynchronous transmitting participants (106_1-106_n) of the communication system (100), wherein the multicast data transmission (124) comprises a synchronization data packet (126) and a payload data packet (128) which references the synchronization data packet (126) in time and / or frequency, wherein the synchronization data packet (126) is transmitted in a frequency range (125) known to the participants (106_1-106_n) of a frequency band (103) of the communication system (100), wherein the synchronization data packet (126) of the multicast data transmission (124) is divided into a plurality of partial synchronization data packets (126_1-126_k) for transmission, wherein each of the plurality of partial synchronization data packets (126_1-126_k) comprises a portion of the synchronization data packet (126), and wherein the plurality of partial synchronization data packets (126_1-126_k) are transmitted distributed in time and / or frequency according to a time hopping and frequency hopping pattern known to the participant (106_1), wherein the plurality of partial synchronization data packets (126_1-126_k) are transmitted according to the time hopping and frequency hopping pattern of the synchronization data packet (126) within the frequency range (125) known to the participants (106_1-106_n), wherein the frequency range (125) known to the participants (106_1-106_n) corresponds at most to a reception bandwidth of a receiver of the participants (106_1-106_n), Therein, the frequency band used by the communication system includes a bandwidth at least 5 times larger than the reception bandwidth of the receiver of the participant.

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