Method for detecting a failure in a slot-based random-access procedure of a wireless device in a communication network

Abstract

A method for detecting a failure in a slot-based random-access procedure of a wireless device (14a, 14b, 14c; 14), preferably an ambient IoT (Internet of Things) device, in a communication network (10), wherein the method (100) comprises: - Transmitted, by the wireless device (14a, 14b, 14c; 14), a first message of the random access procedure to a node (12) of the communication network (10), wherein the first message comprises a random value and / or device identification information, for requesting access to a transmission medium of the communication network (10), preferably for requesting transmission resources from the node (12); and - Detect, by the wireless device (14a, 14b, 14c; 14), a failure of a random access procedure when no response to the first message is received by the wireless device (14a, 14b, 14c; 14) within a period of time represented by a defined number of slots.

Description

[0001] The invention relates to two corresponding methods for detecting a failure in a slot-based random-access procedure of a wireless device, preferably an Ambient IoT (Internet of Things) device, in a communication network. The invention further relates to a wireless device, preferably an Ambient IoT device, a node, a computer program, and a non-volatile, computer-readable medium. background

[0002] The state of the art for ambient IoT devices, as currently investigated by 3GPP, comprises low-complexity, low-power wireless devices designed for various use cases, such as inventory management, localization, and sensor data exchange in indoor and outdoor environments. These wireless devices are categorized into three main groups, each with different power consumption and transmission characteristics.

[0003] Type 1 devices have a peak power consumption of approximately 1 µW, include an energy storage device, and have an initial sampling frequency offset (SFO) of up to 10X ppm. They have no in-device gain for either downlink (DL) or uplink (UL) transmission, and their UL transmission is based on backscattering an externally provided carrier wave.

[0004] Devices of types 2a and 2b have a peak power consumption of a few hundred µW, include an energy storage device, and exhibit an initial SFO of up to 10X ppm. Both types feature amplification for DL ​​and / or UL transmission, with type 2a devices generating UL transmissions by backscattering externally supplied carrier waves and type 2b devices generating UL transmission internally.

[0005] The ambient IoT device can be designed to communicate directly and bidirectionally with a user device or base station. Alternatively, the ambient IoT device can be designed to communicate indirectly and bidirectionally with a base station via at least one intermediate node, such as a user device (UE), a reader, or a relay.

[0006] The ambient IoT device can also be configured to receive downlink transmissions directly from a base station and to receive uplink transmissions to the base station via at least one auxiliary node. Alternatively, the ambient IoT device can be configured to receive a downlink transmission from the base station via at least one auxiliary node and to transmit uplink transmissions directly to the base station.

[0007] The random access procedure for these ambient IoT devices can be based on a slotted ALOHA media access (MAC) protocol, where devices access the channel only to start a time slot when triggered by the network. In the event of a collision, a resolution mechanism is required to address simultaneous channel access by multiple ambient IoT devices.

[0008] The random access procedure for ambient IoT devices can be categorized based on the number of message exchanges and the approach to conflict resolution: The procedure can be classified as two-step, three-step, or four-step, depending on the specific sequence of message exchanges involved in initiating and concluding the random access process. Additionally, the procedure can be categorized as conflict-based or conflict-free, based on whether specific mechanisms are used to mitigate conflicts and resolve collisions during channel access.

[0009] In conventional wireless networks using random-access transmission, UEs transmit a random-access preamble over the uplink random-access channel. The network responds with a random-access response. The UEs respond with a conflict resolution identifier (CRID) that is identified by the network. The network then grants the channel to a specified UE based on resources and priority, while other UEs attempt to access the channel at a later random time.

[0010] When an Ambient IoT device is triggered by the network or a reader, it initiates the random access procedure. During this process, messages exchanged between Ambient IoT devices and readers can be lost due to collisions or poor channel conditions, highlighting the need for message failure detection and the implementation of a recovery procedure. Disclosure of the invention

[0011] According to a first aspect, a method for detecting a failure in a slot-based random access procedure of a wireless device, preferably an ambient IoT (Internet of Things) device, in a communication network is provided.

[0012] The procedure according to the first aspect includes: - Transmitted, through the wireless device, an initial message of the random access procedure to a node of the communication network, wherein the first message includes a random value and / or device identification information, for requesting access to a network transmission medium, preferably for requesting transmission resources from the node; and - Detect, by the wireless device, a failure of a random access procedure if no response to the first message is received by the wireless device within a period of time represented by a defined number of slots.

[0013] The method according to the first aspect can be understood as a method for wireless communications, in particular for operating the wireless device, preferably the ambient IoT device, of the communication network.

[0014] According to a second aspect, a method for detecting a failure in a slot-based random access procedure of a wireless device, preferably an ambient IoT (Internet of Things) device, in a communication network is provided.

[0015] The procedure according to the second aspect includes: - Receiving, by a node of the communication network, a first message of the random access procedure transmitted by the wireless device, wherein the first message includes a random value and / or device identification information, to request access to a transmission medium of the network, preferably to request transmission resources from the node; - Transmitted, through the node, a second message of the random-access procedure in response to receiving the first message, wherein the second message comprises: the random value and / or the device identification information contained in the first message, and / or o resource information about transmission resources allocated to the wireless device; and - Detect, by the node, a failure of a random access procedure if no response to the second message is received by the node within a period represented by a defined number of slots.

[0016] The procedure according to the second aspect can be understood as a procedure for communications, in particular for operating the node of the communication network.

[0017] According to a third aspect, a wireless device, preferably an Ambient IoT device, is provided as part of a communication network. The wireless device is designed to perform the method according to the first aspect or its embodiments.

[0018] According to a fourth aspect, a node, preferably a radio node, of a communication network is provided. The node is designed to execute the method according to the second aspect or its embodiments.

[0019] According to a fifth aspect, a computer program is provided that includes machine-readable instructions to cause the following: - the wireless device, as defined by the third aspect, performs the method according to the first aspect and / or its embodiments, and / or - the node, as defined by the fourth aspect, performs the procedure according to the second aspect and / or its embodiments.

[0020] According to a sixth aspect, a non-volatile, computer-readable medium is provided on which the computer program, as defined by the sixth aspect, is stored.

[0021] The communication network can comprise a wireless network and a core network. The communication network can be configured as a cellular network, preferably according to 3GPP specifications, e.g., 3GPP Release 18 or later, or as a wireless local area network (LAN), preferably according to IEEE specifications. The communication network includes at least the wireless device and the node.

[0022] The wireless device can be configured as a low-energy or low-power device. The wireless device can have a peak power consumption of less than 1 mW, preferably less than 500 µW, particularly less than 100 µW, and in one embodiment less than 10 µW, e.g., approximately 1 µW.

[0023] The wireless device is preferably configured for energy harvesting, thereby utilizing ambient energy sources, such as radio waves, thermal radiation, mechanical vibrations, etc., as a power source. The wireless device may or may not include an energy storage device, such as a battery.

[0024] In particular, the wireless device differs from a reduced-capability device (redcap device), a narrowband IoT (NB-IoT) device, or an enhanced machine-type communication (eMTC) device, for example, due to its lower hardware complexity, lower cost, and / or smaller form factors. Additionally, communication between the wireless device and the node may not be controlled by a radio resource control (RRC) layer. Specifically, a hybrid automated retry request (HARQ) procedure may not be used or may not be applicable for communication between the wireless device and the node.

[0025] The wireless device can be located on or be part of the following: - an environmental sensor used, for example, in smart buildings, industrial plants and urban infrastructure to enable environmental monitoring and control, - a smart home device to enable remote monitoring and control of residential environments for energy efficiency, security and comfort, - a wearable health and / or fitness tracker to enable personal health and fitness tracking as well as remote patient monitoring in healthcare applications, - an asset tracking device to enable monitoring of the location and status of assets, vehicles and inventory in logistics, transportation and supply chain applications, - an industrial IoT sensor and / or actuator to enable the monitoring and control of machines, devices and processes, - an intelligent agricultural device to enable the optimization of resource use and improvement of crop yields, - a smart city infrastructure unit to enable intelligent street lighting, traffic monitoring, waste management, public safety and environmental monitoring.

[0026] The node of the communication network can be a radio or wireless node, or a core network node. The radio node can be a base station, a user device configured, for example, as a reader for Ambient IoT devices, a relay, or an IAB (Integrated Access and Backhaul).

[0027] The random access procedure preferably includes at least the transmission of the first message of the random access procedure from the wireless device to the node and the transmission of the second message of the random access procedure from the node to the wireless device.

[0028] The first message may include or consist of the random access preamble. The random access preamble may include a random number and / or device identification information.

[0029] The second message may include or consist of the random access response. The random access response may be an echo of the random number and / or device identification information contained in the random access preamble.

[0030] Random-access procedure messages transmitted between the node and the wireless device—that is, messages transmitted by the wireless device and received by the node, and / or messages transmitted by the node and received by the wireless device—can be transmitted either directly, specifically on the physical random-access channel (PRACH), or indirectly via an intermediate or auxiliary node of the communication network. For example, a message received by the wireless device can be transmitted from a core node of the communication network to the wireless device via a radio node, such as a base station, of the communication network, and vice versa.

[0031] The failure of the random access procedure can result in the loss of one of the messages from the wireless device's random access procedure. In a three- or four-step random access procedure, the first message transmitted from the wireless device to the node, and / or the second message transmitted from the node to the wireless device, and / or the third message transmitted from the wireless device to the node, can be lost. In a two-step random access procedure, the first message transmitted from the wireless device to the node, and / or the second message transmitted from the node to the wireless device, can be lost.The failure of the random access procedure can also be a loss of a possible negative acknowledgment (NACK) transmitted in response to a failed transmission of the second and / or third message.

[0032] The detection of a random access procedure failure is based on the non-receipt of an expected response message to a transmitted random access procedure message within a period represented by a defined number of slots. More precisely, the period corresponds to the duration of a slot multiplied by a natural number. The period can be one slot or N slots, corresponding to a round of the random access channel conflict. The number N of slots defining a random access procedure conflict round can be configured by the network or a reader node. The period can correspond to the number of slots in the current or next random access channel conflict round. The period can also be set by the node as a time, a counter, or the duration of a scheduled time slot for receiving the third message.

[0033] The proposed solution effectively addresses the challenge of detecting transmission failures in a slot-based random-access procedure of a wireless device. By enabling fast and efficient detection of failed transmissions, recovery steps can be initiated early, preventing potential resource waste and improving energy efficiency. This is particularly beneficial for low-power or low-energy wireless devices, such as ambient IoT devices, where resources must be carefully managed.

[0034] According to one embodiment of the first aspect, the method further comprises: - Prior to transmitting the first message, the node receives a trigger message, transmitted by the node or another node in the communication network, to trigger the random access procedure, with the first message being transmitted in response to receiving the trigger message.

[0035] Accordingly, the method according to one embodiment of the second aspect further comprises: - Before receiving the first message, the node transmits a trigger message to the wireless device to initiate the random access procedure.

[0036] The additional node can be a core network node or a radio node, such as a base station or a user device. The trigger message can be part of a paging message transmitted over a paging channel of the communication network. This enables efficient and coordinated initiation of the random access procedure, thereby reducing collisions and conflicts with other devices attempting to access the network.

[0037] According to one embodiment of the first aspect, the method further comprises: - Transmitted, through the wireless device, a further first message of the random access procedure to the node based on the detected failure, wherein the further first message includes the random value or another random value and / or the device identification information, to request access to the network's transmission medium, preferably to request transmission resources from the node.

[0038] In other words, to detect a loss of the first or second message, a counter or timer can be set by the wireless device to receive a response or feedback on the transmission of the first message, e.g., information about winning a conflict for access to the transmission medium, in particular the random value and / or device identification information as contained in the first message. When the timer or counter reaches a defined value corresponding to the defined number of slots, the next first message is transmitted. Here, the defined number of slots can also be represented by a limited time window defined as one or more rounds of conflicts for random channel access. Preferably, the next first message is transmitted if no feedback or response is received within the time window. That is to say,The wireless device can be configured to wait for a limited time, such as a set of slots defined as a round, and try again, or to immediately repeat the first message after a time window, depending on whether a timer or counter reaches a threshold defined by a specified number of slots. A configuration for waiting for a certain number of slots or rounds can be based on a configuration received from the network, such as the core network, or from a base station or reader, or configured by higher layers.

[0039] The transmission of the subsequent first message can be a retransmission of the first message or a transmission with a new random value. Here, the subsequent first message can additionally or alternatively include the device identification information. This enables proactive recovery from detected failures in the random access procedure, allowing the wireless device to adapt and potentially avoid the same collision or conflict, thereby improving overall efficiency and reliability.

[0040] According to one embodiment of the first aspect, the method further comprises: - Receiving, by the wireless device, a second message transmitted by the node in response to the reception of the first message and / or the subsequent first message, the second message includes: ◯ the random value and / or the device identification information contained in the first and / or subsequent first message, and / or o resource information about transmission resources allocated to the wireless device.

[0041] The second message can be the random access response. It can include an echo of the random number and / or device identification information. Additionally or alternatively, the second message can specify network transmission resources allocated for a transmission or one or more retransmissions by the wireless device. For example, the resource information can specify a slot or set of slots allocated for a transmission by the wireless device. Furthermore, the second message can include control information. This allows for efficient signaling to the wireless device to proceed to step three of a three- or four-step random access procedure or to begin payload transmission in a two-step random access procedure.

[0042] According to one embodiment of the first aspect, the method further comprises: - Transmitted by the wireless device, in response to the reception of the second message, a third message to the node, preferably using the allocated transmission resources, wherein the third message includes device identification information and / or data using the allocated transmission resources.

[0043] The third message can be a third message of the random access procedure or a third message transmitted after the successful completion of the random access procedure, i.e., after successful access to the transmission medium or channel. The third message preferably includes (only) the device identification if the first message does not include the device identification. The third message can also be a payload transmission. This allows the wireless device to effectively utilize the allocated transmission resources by transmitting data or device identification information.

[0044] According to one embodiment of the first aspect, the method further comprises: - Receiving, through the wireless device, a further second message transmitted by the node, - the second message includes: ◯ the random value and / or the device identification information contained in the first and / or subsequent first message, and / or ◯ Resource information about the or alternative transmission resources allocated to the wireless device; and / or ◯ a negative confirmation of not receiving a reply to the second message within a further period, represented by a further defined number of slots; and - Retransmitting, through the wireless device, the third message to the node in response to the reception of the further second message, preferably using the resources specified by the resource information of the further second message.

[0045] The second message can be transmitted by the node if no response to the second message is received by the node within the specified waiting period. This waiting period (the node waits for a response) can be different from or the same as the waiting period (the wireless device waits for a response). The wireless device's receipt of the second message can be interpreted as the node's implicit acknowledgment that the third message was not received.

[0046] If the second message includes the negative acknowledgment, the negative acknowledgment is explicit. This allows the wireless device to effectively respond to potential communication failures by retransmitting the third message, thus ensuring robustness and reliability in the random-access procedure.

[0047] According to one embodiment of the second aspect, the method further comprises: - Received by the node, another first message of the random access procedure after the transmission of the second message procedure, - the further first message includes: ◯ the or another random value, and / or ◯ the device identification information for requesting transmission resources from the node; and - Detect, through the node, the failure of the random access procedure based on the receipt of the next first message.

[0048] Based on the receipt of a second initial message, specifically instead of a third, a loss of the second message by the node can be detected. This represents an additional or alternative option for effectively detecting a failure of the random access procedure.

[0049] According to one embodiment of the second aspect, the method further comprises: - Transmitted, through the node, a further second message of the random access procedure in response to the detected failure of the random access procedure, - the second message includes: ◯ the random value and / or device identification information contained in the first message, and / or ◯ Resource information about the or alternative transmission resources allocated to the wireless device; and / or ◯ a negative confirmation of not receiving a reply to the second message within the period represented by the defined number of slots.

[0050] Preferably, in the event of a loss of the second or third message, the node can be configured to repeat the same second message to induce the selected wireless device to begin transmission on the scheduled time slot. If the scheduled time slot has already expired, a new schedule can be included in the subsequent second message. Additionally or alternatively, a negative acknowledgment is transmitted to the wireless device. Successful transmission of the third message is essential, as it indicates that the wireless device has successfully gained access and has been identified within the random access procedure.

[0051] In a two-step random access procedure, a response to the second message can be one or more messages containing data or payload. Similarly, in a four-step random access procedure, a response to the second message can be one or more messages containing data or payload. Here, the one or more messages are transmitted by the wireless device to the node after successful completion of the random access procedure, i.e., after successful access to the channel.

[0052] If the one or more messages containing data or payload are not received by the node in the corresponding slots allocated for the transmission(s), the node detects a failure. After detecting the transmission failure of the one or more messages containing data or payload, the detected failure can be communicated to the wireless device. To communicate the detected failure, a message containing a negative acknowledgment can be transmitted from the node to the wireless device. Additionally or alternatively, the node can schedule new transmission resources for the wireless device, preferably for one or more retransmissions of the failed transmission(s) and / or for transmissions of additional messages.According to one embodiment, the detected failure can be indicated by the node using a single bit that is signaled to the wireless device.

[0053] In other words, it is proposed that if the third message is not received by the node within one round or the defined period using a timer or counter, or on a scheduled time slot for the third message, the node sends a negative acknowledgment to the wireless device to trigger a retransmission of the third message. Additionally or alternatively, the node can send a new scheduled time for the third message. As a further alternative, the transmission of the second message can be repeated, optionally including any additional information already transmitted with the second message. This allows the wireless device to be signaled, implicitly or explicitly, about the loss of the second or third message.

[0054] According to one embodiment of the second aspect, the method further comprises: - Detect, by the node, a further failure of a random-access procedure if no response to the further second message is received by the node within a further period represented by a further defined number of slots; and - Retransmitted, through the node, the further second message, preferably with a specified periodicity and / or for a specified plurality of times.

[0055] Preferably, the second message, which includes the negative acknowledgment, is retransmitted. In other words, if a negative acknowledgment for non-receipt of a response to the second message is lost, the node is expected to retransmit the third message, expecting the wireless device to receive further messages from the node, containing, for example, control information as scheduling information for the payload transmission. To resolve this situation, the node should retransmit the second message, which includes the NACK, several times within a specific time period. Additionally or alternatively, the wireless device can be configured to remain in sleep mode until control information for the payload transmission is provided.

[0056] The periodicity or specified plurality of retransmissions can depend on - an impending traffic and / or access need in the communication network, and / or - a buffer status report from at least one other wireless device, and / or - be fixed and different for specific types of wireless devices, e.g., Ambient IoT device categories Type 1, 2a, 2b, and / or - be suitable for all types of wireless devices.

[0057] This improves the chances that the wireless device will successfully access the transmission medium.

[0058] According to one embodiment of the second aspect, the method further comprises: - Receiving, by the node, a third message transmitted by the wireless device, wherein the third message includes device identification information and / or data transmitted by the wireless device using the allocated transmission resources.

[0059] This allows for the successful completion of the random access procedure.

[0060] According to one embodiment of the second aspect, the method further comprises: - Transmitted by the node, in response to the detected failure and / or the detected further failure, failure information to another node of the communication network, wherein the failure information includes the device identification information and optionally information about the detected failure and / or the detected further failure, e.g. a type or category of failure.

[0061] The failure information can be transmitted to a node of a core network of the communication system.

[0062] In other words, transmissions between the wireless device and the node may fail, particularly multiple times, due to blockages, low power levels, hardware malfunctions, or any other reason. The failure information is preferably used to report such a failure, e.g., a malfunctioning wireless device, to the core network. The failure information can be contained in a failure message transmitted over a wireless or wired channel of the communication network. The failure message can include an identifier for the wireless device and, optionally, a type or category of failure or malfunction.

[0063] Preferably, based on the transmitted failure information, corresponding wireless devices are excluded from subsequent paging phases by other nodes, such as wireless device readers, of the communication network. The communication network, particularly the core network, can utilize the failure information for applications such as "maintenance of ambient IoT devices." This increases the efficiency of the random access procedure for other nodes of the communication network by preventing the waste of resources on malfunctioning wireless devices. Furthermore, it enables the initiation of processes to adjust channel conditions or device settings to prevent future failures of the wireless device's random access procedure.

[0064] According to one embodiment of the second aspect, the method further comprises: - Transmitted through the node in response to the detected failure and / or the detected further failure, ◯ a trigger message to another wireless device in the communication network to trigger the random access procedure of the other wireless device, and / or ◯ a second message of a random-access procedure from another wireless device to the other wireless device.

[0065] The second message can be transmitted to the other wireless device if the node has already received the first message from the other wireless device's random access procedure. The other wireless device may initially have lost a conflict against the other wireless device for access to the transmission medium.

[0066] In other words, regardless of whether the random-access procedure involves the transmission of two, three, or four messages, if a transmission of the message from the node to the wireless device fails several times or rounds, instead of repeatedly transmitting the same second message, the node can assume unfavorable channel conditions. In this case, the node can select a different wireless device on the communication network. Specifically, the failed or lost message can be regenerated with new content, for example, a newly selected random value, a new selected identifier, or a new selected device ID, to avoid wasting resources such as the energy consumption of competing wireless devices.

[0067] According to another aspect of the invention, a (wireless) communication network is provided which includes at least the wireless device and the node.

[0068] According to a further aspect of the invention, a method for operating the communication network is provided. The method for operating the communication network comprises the steps of the method according to the first aspect or its embodiments and the steps of the method according to the second aspect or its embodiments.

[0069] The non-volatile, computer-readable medium is preferably designed to store the computer program to be executed by a processor of the first LAN element and / or the second LAN element and / or the communication network. The non-volatile, computer-readable media may include RAM, ROM, EEPROM, and any other persistent storage device. Description of the characters

[0070] Exemplary embodiments of the present invention are shown in the figures, which are not to be regarded as limiting the claims, and are explained in more detail below. Fig. Figure 1 schematically illustrates a communication network according to embodiments of the invention; and Fig. Figures 2A and 2B schematically illustrate two methods according to embodiments of the invention.

[0071] Fig. Figure 1 schematically illustrates a communication network 10 according to one aspect of the invention. The communication network 10 is configured as a cellular communication network 10, preferably according to 3GPP specifications. The communication network 10 can comprise a core network and a wireless network.

[0072] The communication network 10 comprises a radio node 12 configured as a user device 12, or a reader 12 for an Ambient IoT (Internet of Things) device, or a relay node acting as a reader, and a plurality of wireless devices 14a, 14b, 14c, preferably configured as Ambient IoT devices 14a, 14b, 14c, particularly according to 3GPP specifications. The wireless devices 14a, 14b, 14c are collectively represented by reference numerals 14. The communication network 10 further comprises a radio node 16 configured as a base station 16.

[0073] To request access to a transmission medium of the communication network 10, the wireless devices 14 are designed to perform a method for initiating a preferably slot-based random access procedure. Here, the random access procedure can be based on a slotted ALOHA random access MAC protocol. That is, the wireless devices 14 are designed to begin a transmission only at the beginning of a slot. The length of the slot is preferably equal to the sum of a packet transmission time and a maximum propagation delay in the network to ensure that both the transmission and reception of a data packet can be completed within a slot.

[0074] The random access procedure can be set up between the respective wireless devices 14a, 14b, 14c and the reader 12, or between the respective wireless devices 14a, 14b, 14c and the base station 16. In the latter case, transmission between the wireless devices 14 and the base station 16 can be routed or forwarded via the reader 12.

[0075] According to an alternative embodiment, the base station 16 can be configured as a reader for the wireless devices 14. Accordingly, messages of the random access procedure are transmitted directly between the base station 16 and the wireless devices 14a, 14b, 14c (i.e., without routing them via the radio node 12).

[0076] The wireless devices 14 are designed to detect a failure in the slot-based random-access procedure of the respective wireless device 14 by performing the method according to the first aspect of the invention and / or its embodiments, as further described in Fig. 2A described, configured.

[0077] Node 12 and / or node 16 are used to detect a failure in the slot-based random-access procedure of the wireless devices 14 by performing the method according to the second aspect of the invention and / or its embodiments, as further described in Fig. 2B described, configured.

[0078] Fig. Figure 2 schematically illustrates two methods according to embodiments of the invention.

[0079] Fig. Figure 2A schematically illustrates a method 100 for detecting a failure in a slot-based random-access procedure of a wireless device 14a, preferably an ambient IoT (Internet of Things) device 14a, e.g. according to Fig. 1, in a communication network according to the first aspect of the invention.

[0080] The procedure 100 includes an optional step 110 for receiving, by the wireless device 14a, a trigger message transmitted by one node or another node of the communication network, to trigger the random access procedure.

[0081] Method 100 comprises a step 120 for transmitting, via the wireless device 14a, a first message of the random access procedure to a node of the communication network. The first message is preferably transmitted in response to the receipt of the trigger message. The first message includes a random value and / or device identification information for requesting access to a transmission medium of the network, preferably for requesting transmission resources from the node.

[0082] The procedure 100 includes a step 130 for detecting, by the wireless device 14a, a failure of a random-access procedure if no response to the first message is received by the wireless device 14a within a period of time represented by a defined number of slots.

[0083] Method 100 includes an optional step 140 for transmitting, through the wireless device 14a, a further first message of the random access procedure to the node based on the detected failure. The further first message includes the or further random value and / or the device identification information for requesting access to a transmission medium of the network, preferably for requesting transmission resources from the node.

[0084] Fig. Figure 2B schematically illustrates a method 200 for detecting a failure in a slot-based random access procedure of a wireless device, preferably an ambient IoT (Internet of Things) device, in a communication network according to the second aspect of the invention.

[0085] The procedure 200 includes an optional step 210 for transmission through a node 12 of the communication network, e.g. the reader 12 according to Fig. 1, a trigger message to the wireless device to trigger the random access procedure.

[0086] Method 200 comprises a step 220 for receiving, by node 12, a first message of the random access procedure transmitted by the wireless device. The first message includes a random value and / or device identification information for requesting access to a transmission medium of the network, preferably for requesting transmission resources from node 12.

[0087] Procedure 200 includes a step 230 for transmitting, through node 12, a second message of the random-access procedure in response to receiving the first message. The second message includes - the random value and / or device identification information contained in the first message, and / or - Resource information about transmission resources allocated to the wireless device.

[0088] Procedure 200 includes a step 240 for detecting, by node 12, a failure of a random access procedure if no response to the second message is received by the node within a period of time represented by a defined number of slots.

[0089] Procedure 200 includes an optional step 250 for transmitting, through node 12, a further second message of the random access procedure in response to the detected failure of the random access procedure. This further second message includes - the random value and / or device identification information contained in the first message, and / or - resource information about the or alternative transmission resources allocated to the wireless device; and / or - a negative confirmation of not receiving a reply to the second message within the period represented by the defined number of slots.

[0090] Method 200 includes an optional step 260 for transmitting, by node 12, in response to the detected failure, failure information to another node of the communication network. The failure information includes the device identification information and optionally information about the detected failure and / or the detected further failure, e.g., a type or category of failure.

[0091] The procedure 200 includes an optional step 270 for transmitting, by node 12, in response to the detected failure, a trigger message to another wireless device of the communication network to trigger the random access procedure of the other wireless device.

Claims

[1] Method (100) for detecting a failure in a slot-based random access procedure of a wireless device (14a, 14b, 14c; 14), preferably an ambient IoT (Internet of Things) device, in a communication network (10), wherein the method (100) comprises: - Transmitted (120), by the wireless device (14a, 14b, 14c; 14), a first message of the random access procedure to a node (12) of the communication network (10), wherein the first message includes a random value and / or device identification information, to request access to a transmission medium of the communication network (10), preferably to request transmission resources from the node (12); and - Detect (130) by the wireless device (14a, 14b, 14c; 14) a failure of a random access procedure when no response to the first message is received by the wireless device (14a, 14b, 14c; 14) within a period of time represented by a defined number of slots. [2] Method (100) according to claim 1, further comprising: - prior to the transmission (120) of the first message, receiving (110) by the node (12), a trigger message transmitted by the node (12) or another node (16) of the communication network (10) to trigger the random access procedure, wherein the first message is transmitted in response to the receipt (110) of the trigger message. [3] Method (100) according to claim 1 or 2, further comprising: - Transmitted (140) by the wireless device (14a, 14b, 14c; 14) a further first message of the random access procedure to the node (12) based on the detected failure, wherein the further first message includes the or a further random value and / or the device identification information, to request access to the transmission medium of the communication network (10), preferably to request transmission resources from the node (12). [4] Method (100) according to any one of the preceding claims, further comprising: - Receiving, by the wireless device (14a, 14b, 14c; 14), a second message transmitted by the node (12) in response to the reception of the first message and / or the further first message, the second message comprising: ◯ the random value and / or the device identification information contained in the first and / or subsequent first message, and / or ◯ Resource information about transmission resources allocated to the wireless device (14a, 14b, 14c; 14). [5] Method (100) according to claim 4, further comprising: - Transmitted by the wireless device (14a, 14b, 14c; 14), in response to the reception of the second message, a third message to the node (12), preferably using the allocated transmission resources, wherein the third message includes a device identification information and / or data using the allocated transmission resources. [6] Method (100) according to claim 5, further comprising: - Receiving, by the wireless device (14a, 14b, 14c; 14), a further second message transmitted by the node (12), - the second message includes: ◯ the random value and / or the device identification information contained in the first and / or subsequent first message, and / or ◯ resource information about the or alternative transmission resources allocated to the wireless device (14a, 14b, 14c; 14); and / or o a negative acknowledgment of not receiving a reply to the second message within a further period represented by a further defined number of slots; and - Retransmitted, by the wireless device (14a, 14b, 14c; 14), the third message to the node (12) in response to the reception of the further second message. [7] Method (200) for detecting a failure in a slot-based random access procedure of a wireless device (14a, 14b, 14c; 14), preferably an ambient IoT (Internet of Things) device, in a communication network (10), wherein the method (200) comprises: - Receiving (220), by a node (12) of the communication network (10), a first message of the random access procedure transmitted by the wireless device (14a, 14b, 14c; 14), wherein the first message includes a random value and / or device identification information, to request access to a transmission medium of the communication network (10), preferably to request transmission resources from the node (12); - Transmitted (230), through node (12), a second message of the random-access procedure in response to receiving the first message, wherein the second message comprises: ◯ the random value and / or device identification information contained in the first message, and / or ◯ Resource information about transmission resources allocated to the wireless device (14a, 14b, 14c; 14); and - Detect (240), by node (12), a failure of a random access procedure if no response to the second message is received by node (12) within a period of time represented by a defined number of slots. [8] Method (200) according to claim 7, further comprising - prior to receiving (220) the first message, transmitting (210) through the node (12) a trigger message to the wireless device (14a, 14b, 14c; 14) to trigger the random access procedure. [9] Method (200) according to claim 7 or 8, further comprising: - Received, by node (12), another first message of the random access procedure after the transmission of the second message procedure, - the further first message includes: ◯ the or another random value, and / or ◯ the device identification information for requesting transmission resources from the node (12); and - Detect, through node (12), the failure of the random access procedure based on the reception of the next first message. [10] Method (200) according to any one of claims 7 to 9, further comprising: - Transmitted (250), through node (12), a further second message of the random access procedure in response to the detected failure of the random access procedure, - the second message includes: ◯ the random value and / or device identification information contained in the first message, and / or ◯ Resource information about the or alternative transmission resources allocated to the wireless device (14a, 14b, 14c; 14); and / or ◯ a negative confirmation of not receiving a reply to the second message within the period represented by the defined number of slots. [11] Method (200) according to claim 10, further comprising: - Detect, by node (12), a further failure of a random-access procedure if no response to the further second message is received by node (12) within a further period represented by a further defined number of slots; and - Retransmitted, through node (12), the further second message, preferably with a specified periodicity and / or for a specified plurality of times. [12] Method (200) according to any one of claims 7 to 11, further comprising: - Received by the node (12) a third message transmitted by the wireless device (14a, 14b, 14c; 14), wherein the third message includes device identification information and / or data transmitted by the wireless device (14a, 14b, 14c; 14) using the allocated transmission resources. [13] Method (200) according to any one of claims 7 to 12, further comprising: - Transmitted (260), by the node (12), in response to the detected failure and / or the detected further failure, a failure information to another node (16) of the communication network (10), wherein the failure information includes the device identification information and optionally information about the detected failure and / or the detected further failure, e.g. a type or category of failure. [14] Method (200) according to any one of claims 7 to 13, further comprising: - Transmitted (270), through the node (12), in response to the detected failure and / or the detected further failure, ◯ a trigger message to another wireless device (14a, 14b, 14c; 14) of the communication network (10) to trigger the random access procedure of the other wireless device (14a, 14b, 14c; 14), and / or ◯ a second message of a random-access procedure from another wireless device to the other wireless device. [15] Wireless device (14a, 14b, 14c; 14), preferably an Ambient IoT (Internet of Things) device, of a communication network (10) designed to perform the method (100) according to any one of claims 1 to 6. [16] Node (12) of a communication network (10) designed to perform the method (200) according to any one of claims 7 to 14. [17] Computer program that includes machine-readable instructions to cause the - the wireless device (14a, 14b, 14c; 14) according to claim 15 performs the method (100) according to any one of claims 1 to 6, and / or - the node (12) according to claim 16 performs the method (200) according to one of claims 7 to 14. [18] Non-volatile computer-readable medium on which the computer program according to claim 17 is stored.

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