Method for initiating a random access procedure of a wireless device in a communication network
The method addresses repeated channel access failures in low-energy wireless devices by implementing a backoff mechanism and dynamic mapping policies, enhancing network performance and power efficiency.
Patent Information
- Authority / Receiving Office
- DE · DE
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-10-02
- Publication Date
- 2026-04-02
AI Technical Summary
Low-energy wireless devices, such as ambient IoT devices, experience repeated channel access failures during random access procedures due to collisions, which are not efficiently addressed by conventional mechanisms, leading to inefficient power consumption and network performance.
A method for initiating a random access procedure that includes detecting access failures, determining a backoff termination condition, and transmitting a further message when the condition is met, utilizing customizable backoff mechanisms and dynamic mapping policies to mitigate collisions and improve channel re-access efficiency.
The method effectively reduces repeated collisions and enhances the efficiency of channel re-access attempts, improving overall system performance and power management in wireless communication networks.
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Abstract
Description
[0001] The invention relates to a method for initiating a 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 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. The ambient IoT device can also 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] If an ambient IoT device does not receive an access response message in response to the transmission of an access preamble, or receives only an access response message containing the random number and / or device identifier of another wireless device, it may attempt to access the transmission medium again by transmitting another access preamble. Such a channel access failure can occur repeatedly for the same wireless device. For a low-energy wireless device, an efficient channel access mechanism is critical. Disclosure of the invention
[0011] According to a first aspect, a method for initiating a 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, by the wireless device, a first 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, to request access to a transmission medium of the communication network, preferably to request transmission resources from the node; - Detect, by the wireless device, a failure of the access request if no response message containing the random value and / or device identification information is received by the wireless device (within a defined period of time); - Determine, by the wireless device, based on the detected failure, a backoff termination condition to transmit another first message of the random access procedure to the node; and - Transmitted, through the wireless device, the further first message of the random access procedure to the node when the backoff termination condition is met, wherein the further first message includes the random value and / or another random value and / or the device identification information.
[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 wireless device, preferably an Ambient IoT device, is provided for a communication network. The wireless device is designed to perform the method according to the first aspect or its embodiments.
[0015] According to a third aspect, a computer program is provided which includes machine-readable instructions that cause the wireless device, as defined by the third aspect, to perform the procedure according to the first aspect and / or its embodiments.
[0016] According to a fourth aspect, a non-volatile, computer-readable medium is provided on which the computer program, as defined by the sixth aspect, is stored.
[0017] 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.
[0018] 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 according to one embodiment less than 10 µW, e.g., approximately 1 µW.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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).
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] The failure of the access request is preferably detected if no response message, in particular no second message of the random access procedure containing the random value and / or the device identification information, is received by the wireless device within a defined period. The defined period can be represented by a defined number of access opportunities, preferably by a defined number of slots.
[0028] 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 conflict round of the random access procedure 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 conflict round. The period can be defined as a timer, a counter, or the duration of a scheduled time slot for receiving the response message.
[0029] Not receiving a reply message containing the random value and / or device identification information can be interpreted as either not receiving a reply message to the first message at all, or receiving a reply message that does not contain the random value and / or device identification information contained in the first message.
[0030] In the first case, the same random value, i.e., the same access opportunity, e.g., the same slot, was potentially selected by at least two wireless devices. Consequently, the same initial message / random access preamble is transmitted by at least two devices, generating interference on the random access channel. As a result, the one or more initial messages cannot be successfully received by the node, and no response to the initial message(s) is transmitted by the node.
[0031] In the second case, the first message may have been received by the node. However, instead of the intended wireless device, the node selected a different wireless device for channel access. Consequently, a response to the first message may be received by the wireless device, but it will contain the random value and / or device identification information of the other wireless device.
[0032] The transmission of the additional first message can be understood as an attempt by the wireless device to re-access the transmission medium or channel. Here, the additional first message is transmitted when the backoff termination condition is met. In other words, the method may involve backing off, or refraining from attempting to re-access the transmission medium or channel during a backoff interval or period, and attempting re-access by transmitting the additional first message after the backoff has ended. In other words, the wireless device's attempt to re-access the channel is delayed until the backoff has ended. Preferably, the additional first message includes the random value and / or another random value and / or the device identification information.
[0033] The proposed solution effectively addresses access failures in a wireless device's random access procedure by mitigating repeated collisions. To this end, a customizable backoff mechanism is provided, tailored to device- or network-specific conditions, thereby increasing the efficiency of channel re-access attempts and improving overall system performance in wireless communication networks.
[0034] According to one embodiment, the backoff termination condition specifies a repetition of one or more successive trigger messages, wherein the trigger message(s) can specify a start of at least one of the following: - a paging round that includes several access rounds, - an access round that includes multiple sets of access opportunities, - a set of access opportunities.
[0035] The trigger message can be transmitted by the node or another node in the communication network. The trigger message can be a paging message, transmitted before or at the beginning of each paging round. The trigger message can be a round trigger message, transmitted before or at the beginning of each access round. The trigger message can be an opportunity trigger message, transmitted before or at the beginning of each set of access opportunities. In this case, the backoff termination condition can require delaying the transmission of the next initial message until the next trigger message is received, or the trigger message following the next one, or the trigger message following each subsequent one.As an example, backing-off until the next paging trigger message is received can include receiving one or more round trigger messages and multiple access opportunity trigger messages without accessing the channel again.
[0036] In other words, the transmission of the next first message, when the backoff termination condition is met, can include: - Backing off for an entire current set of access opportunities, preferably slots, and re-accessing the transmission medium after receiving the next trigger message from the node. Multiple access opportunities, preferably slots, can occur after each trigger message. If accessing the transmission medium fails on one opportunity, backing off and re-accessing the transmission medium can occur on the next opportunity within the same round. - Backing-off for an entire current set of opportunities and re-accessing the transmission medium after receiving the trigger message following the next one, or one after the other. In other words, re-accessing the transmission medium can be attempted after receiving one of the subsequent trigger messages received by the node. - Backing-off for the current round and re-accessing the transmission medium in the following round, preferably after receiving a round trigger message. - Backing-off for the current paging round and re-accessing the transmission medium after receiving the next paging message from the node.
[0037] This allows for dynamic adjustment of channel re-access using trigger messages to indicate the end of a backoff interval.
[0038] According to one embodiment, the backoff termination condition indicates the occurrence of a defined access opportunity, in particular a defined slot, for transmitting the next initial message. In other words, the backoff termination condition requires a backoff until a defined access opportunity, represented, for example, by an access opportunity or slot index, occurs. According to this embodiment, the backoff termination condition can be independent of the reception of trigger messages, such as paging trigger, round trigger, or access opportunity trigger messages. This allows for the assignment of specific access opportunities to the wireless device, thereby offering the possibility of further reducing channel collisions.
[0039] According to one embodiment, the method further comprises: - Determine, by the wireless device, the defined access opportunity, in particular the defined slot, for transmitting the further first message, in particular based on the random number and / or the further random number, using a mapping guideline.
[0040] The wireless device may include a random number generator for generating the random number and / or further random numbers. The random number may be generated using a uniform random distribution or another distribution.
[0041] The wireless device can further comprise a mapping policy, e.g., a mapping function or a mapping table, for mapping input data, in particular the random number and / or the further random number, to an index of an access opportunity, preferably a slot. In other words, the mapping policy is designed to map input data such as the random number to an index of an access opportunity, preferably a slot. As an alternative to the random number, an index of an access opportunity, preferably a slot, which is used to transmit the first message, can be used as input data for the mapping policy.
[0042] The mapping policy can be configured as a modulo function. A module of the modulo function can be set to the number of slots, for example, in a paging period (as configured by the node using a paging trigger message) or a rounding period (as configured by the node using a rounding trigger message). Here, the respective mapping policy maps a defined set of random numbers to a defined set of indices of access opportunities. In other words, random number generation is followed by a mapping of the generated random number using the mapping policy.
[0043] The procedure may, prior to transmitting the first message, include determining the random number and mapping the random number to an index of an access opportunity, preferably a slot, using the mapping policy, wherein the first message is transmitted at the access opportunity with the index derived from the random number. The first message may include the determined random number or a random number that differs from the determined random number.
[0044] The method can further comprise, in response to the detected failure, determining the further random number and mapping the further random number to an index of a further access opportunity, preferably a further slot, using the mapping policy, wherein the further first message includes the further random number and is transmitted at the further access opportunity, preferably the further slot, with the index derived from the further random number.
[0045] The method can further comprise, in response to the detected failure, mapping the random number to an index of another access opportunity, preferably using a different mapping policy, wherein the further first message includes the random number and is transmitted at the further access opportunity with the index derived from the further random number. A set of mapping policies can be provided to the wireless device by configuration or preconfiguration. The set of mapping policies is preferably also provided to the node.
[0046] Using a mapping policy to determine the backoff termination condition enables the wireless device's reaccess strategy to be dynamically adjusted in response to detected access failures.
[0047] According to one embodiment, the method further comprises: - Selecting, by the wireless device, the imaging policy from a group comprising at least two imaging policies, the selection being based on at least one of the following: ◯ a failure message, preferably indicating a number of failed access attempts by the wireless device, or o energy information, preferably indicating an energy level of the wireless device, or ◯ buffer information, preferably indicating the size or fill level of a buffer of the wireless device, or ◯ a data piece of information which preferably indicates a criticality of data, in particular in a / the buffer of the wireless device, or ◯ Location information of the wireless device, preferably specifying an identifier of a zone encompassing the wireless device, or ◯ Use case information for the wireless device, preferably specifying a use case as part of which the method is carried out, ◯ an opportunity to transmit the first message.
[0048] The mapping policy set can include at least one modulo function and one uniform random distribution. The mapping policy selection can be performed in response to a detected failure. The use case as part of which the procedure is performed can be a command use case or an inventory use case, such as those specified in the 3GPP Ambient IoT Devices Specification.
[0049] For example, if the energy information indicates a low energy level, a mapping policy can be selected that increases the duration of a backoff interval but reduces the risk of a channel collision leading to a further failure. Conversely, if the energy information indicates a high energy level, a mapping policy can be selected that shortens the duration of a backoff interval at the cost of an increased risk of a channel collision.
[0050] As another example, if the buffer information indicates a low buffer level, a mapping policy can be selected that increases the duration of a backoff interval but reduces the risk of a channel collision leading to another failure. Conversely, if the buffer information indicates a high buffer level, a mapping policy can be selected that shortens the duration of a backoff interval at the cost of an increased risk of a channel collision.
[0051] By introducing a dynamic selection of the mapping policy based on a variety of parameters, the backoff strategy of the wireless device can be adapted to device-based and / or network-based conditions.
[0052] According to one embodiment, the method further comprises: - Selecting, by the wireless device, the imaging policy from a group comprising at least two imaging policies, the selection being made randomly.
[0053] The mapping policy set can include at least one modulo function and a uniform random distribution. Mapping policy selection can be performed in response to a detected failure. For example, each time a failure is detected, a new mapping policy can be randomly selected from the set. This avoids a purely deterministic backoff procedure, significantly reducing the risk of repeated access failures due to successive channel collisions between the same wireless devices.
[0054] According to one embodiment, the method further comprises: - Selecting, by the wireless device, an access opportunity configuration based on the detected failure from a set comprising at least two access opportunity configurations, wherein the at least two access opportunity configurations differ by a duration of individual access opportunities, and - Change, by the wireless device, from a current access opportunity configuration to the selected access opportunity configuration, wherein the defined access opportunity, in particular the defined slot, for transmitting the further first message is based on the selected access opportunity configuration.
[0055] The two or more access opportunity configurations can each have a fixed access opportunity duration. For example, a first access configuration can have an access opportunity duration of 0.1 ms, and a second access configuration can have an access opportunity duration of 0.01 ms.
[0056] The two or more access opportunity configurations can be synchronized such that at least a subset of the access opportunities from each configuration start at the same time. Synchronization can be achieved before the random access procedure, for example, during paging, or regularly, for example, periodically, using known mechanisms such as PTP (Precision Time Protocol), White Rabbit, etc. In the example above, the start of an access opportunity in the first configuration can be aligned with the start of every tenth access opportunity in the second configuration.
[0057] For example, an initial access opportunity configuration can be selected and changed to after a failed access request is detected, and a second access opportunity configuration can be selected and changed to after a subsequent failed access request is detected. Here, the duration of each individual access opportunity configuration is preferably fixed. Furthermore, the duration of the access opportunities for the first configuration can be longer or shorter than the duration of the access opportunities for the second configuration.
[0058] In particular, a third access opportunity configuration can be selected and changed after a subsequent access request failure is detected following a further access request. Here, the duration of the individual access opportunities of the third configuration is preferably also fixed. Furthermore, the duration of the access opportunities of the second configuration can be longer or shorter than the duration of the access opportunities of the third configuration.
[0059] The dynamic selection and modification of access opportunity configurations by the wireless device based on detected failures enables dynamic switching between configurations with different access opportunity durations, further improving the adaptability and efficiency of the wireless device's access attempts.
[0060] According to one embodiment, the set of access opportunity configurations is preconfigured by the communication network and / or depends on the type of wireless device. This allows for different types of wireless devices with varying adaptability to re-access attempts.
[0061] According to one embodiment, the access opportunity configuration is further selected by the wireless device based on a received configuration message. The message can be an access opportunity configuration message, a paging trigger message, a round trigger message, or an access opportunity trigger message transmitted by the node or another node in the communication network. The configuration message can specify an index of the access opportunity configuration, such as the number of access opportunities within a defined duration, e.g., 10 slots per millisecond. This enables device-specific selection of the access opportunity configuration, thus allowing for individualized and flexible configuration choices.
[0062] According to one embodiment, the method further comprises: - Receiving, by the wireless device, a message transmitted by the node, wherein the message specifies a set of access opportunities, in particular a set of slots, and the further message can be transmitted by the wireless device only in one of the access opportunities included in the set.
[0063] The set of access opportunities can be specified in an access opportunity configuration message and / or a paging trigger message and / or a round trigger message and / or an access opportunity trigger message. Specifying a different set of access opportunities to different wireless devices with failed access attempts can further reduce the likelihood of channel collisions for multiple devices attempting to re-access.
[0064] According to one embodiment, the method further comprises: - Receiving, through the wireless device, an access configuration message transmitted by the node, where the access configuration message is used to configure the wireless devices to access the transmission medium of the communication network, where the access configuration message can specify the following: ◯ a number of access rounds per paging round, and / or ◯ a number of sets of access opportunities per access, and / or ◯ a number of access opportunities per set.
[0065] This allows the node to effectively configure the devices with the access-relevant features or parameters.
[0066] According to one embodiment, the method further comprises: - Performing energy harvesting by the wireless device, based on the specified backoff condition, to achieve an energy level of
[0067] The device is designed to increase the power required for transmitting the subsequent first message. Energy harvesting can involve capturing and accumulating energy from the surrounding environment, such as ambient radio frequency waves, thermal radiation, or mechanical vibrations, and converting it into electrical energy to power the device. For this purpose, the wireless device preferably includes an energy storage device, such as a battery. By utilizing the backoff interval for energy harvesting, the wireless device can replenish its energy reserves, ensuring that it has sufficient power to transmit the subsequent first message after the backoff interval.
[0068] According to one embodiment, the method further comprises: - Prior to transmitting the first message, the wireless device receives a trigger message transmitted by the node or another node of the communication network to initiate the random access procedure, with the first message being transmitted in response to the receipt of the trigger message.
[0069] 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.
[0070] 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 further first message, wherein the second message comprises: ◯ 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.
[0071] 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.
[0072] According to another aspect of the invention, a (wireless) communication network is provided which includes at least the wireless device and the node.
[0073] 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
[0074] 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. Figure 2 schematically illustrates a method according to an embodiment of the invention.
[0075] 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.
[0076] 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.
[0077] 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.
[0078] 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.
[0079] 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).
[0080] The wireless devices 14 are for initiating a 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. 2 described, configured. In particular, the wireless devices 14 are designed for backing-off after the detection of a failed channel access attempt.
[0081] Fig. Figure 2 schematically illustrates a method 100 for initiating a preferably slot-based random access procedure of a wireless device, preferably an ambient IoT (Internet of Things) device, in a communication network.
[0082] Method 100 comprises a step 110 for transmitting, through the wireless device, a first message of the random access procedure to a node of the communication network. The first message includes a random value and / or device identification information for requesting access to a transmission medium of the communication network, preferably for requesting transmission resources from the node.
[0083] Method 100 includes a step 120 for detecting, by the wireless device, a failure of the access request if no response message containing the random value and / or device identification information is received by the wireless device.
[0084] Procedure 100 includes a step 130 to determine, by the wireless device, based on the detected failure, a backoff termination condition to transmit another first message of the random access procedure to the node.
[0085] According to one embodiment, the backoff termination condition specifies a repetition of one or more successive trigger messages, wherein the trigger message(s) can specify a start of at least one of the following: - a paging round that includes several access rounds, - an access round that includes multiple sets of access opportunities, - a set of access opportunities.
[0086] According to an alternative embodiment, the backoff termination condition indicates the occurrence of a defined access opportunity, in particular a defined slot, for transmitting the next first message.
[0087] Procedure 100 includes a step 140 for transmitting, through the wireless device, the further first message of the random access procedure to the node when the backoff termination condition is met. The further first message includes the random value and / or another random value and / or the device identification information.
Claims
[1] Method (100) for initiating a random access procedure of a wireless device (14a, 14b, 14c; 14), preferably an ambient IoT (Internet of Things) device (14a, 14b, 14c; 14) in a communication network (10), wherein the method (100) comprises: - Transmitted (110) 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); - Detect (120) by the wireless device (14a, 14b, 14c; 14) a failure of the access request if no response message including the random value and / or device identification information is received by the wireless device (14a, 14b, 14c; 14); - Determine (130), by the wireless device (14a, 14b, 14c; 14), based on the detected failure, a backoff termination condition to transmit another first message of the random access procedure to the node (12); and - Transmitted (140), through the wireless device (14a, 14b, 14c; 14), the further first message of the random access procedure to the node (12) when the backoff termination condition is met. [2] Method (100) according to claim 1, wherein the backoff termination condition specifies a repetition of one or more successive trigger messages, wherein the trigger message(s) can specify a start of at least one of the following: - a paging round that includes several access rounds, - an access round that includes multiple sets of access opportunities, - a set of access opportunities. [3] Method (100) according to one of the preceding claims, wherein the backoff termination condition specifies the occurrence of a defined access opportunity, in particular a defined slot, for transmitting the further first message. [4] Method (100) according to claim 3, further comprising: - Determine, by the wireless device (14a, 14b, 14c; 14), the defined access opportunity, in particular the defined slot, for transmitting the further first message, in particular based on the random number and / or the further random number, using a mapping guideline. [5] Method (100) according to claim 4, further comprising: - Selecting, by the wireless device (14a, 14b, 14c; 14), the mapping guideline from a group comprising at least two mapping guidelines, the selection being made based on at least one of the following: ◯ a failure information, preferably indicating a number of failed access attempts by the wireless device (14a, 14b, 14c; 14), or ◯ Energy information, preferably indicating an energy level of the wireless device (14a, 14b, 14c; 14), or ◯ buffer information, preferably indicating a size or fill level of a buffer of the wireless device (14a, 14b, 14c; 14), or ◯ a data information which preferably indicates a criticality of data, in particular in a / the buffer, of the wireless device (14a, 14b, 14c; 14), or ◯ location information of the wireless device (14a, 14b, 14c; 14), which preferably specifies an identifier of a zone encompassing the wireless device (14a, 14b, 14c; 14), or ◯ an application case information of the wireless device (14a, 14b, 14c; 14) which preferably specifies an application case as part of which the method (100) is carried out, ◯ an opportunity to transmit the first message. [6] Method (100) according to claim 4, further comprising: - Selecting, by the wireless device (14a, 14b, 14c; 14), the imaging guideline from a group comprising at least two imaging guidelines, wherein the selection is made randomly. [7] Method (100) according to any one of the preceding claims, further comprising: - Selecting, by the wireless device (14a, 14b, 14c; 14), an access opportunity configuration based on the detected failure from a set comprising at least two access opportunity configurations, wherein the at least two access opportunity configurations differ by a duration of individual access opportunities, and - Change, by the wireless device (14a, 14b, 14c; 14), a current access opportunity configuration to the selected access opportunity configuration, wherein the defined access opportunity, in particular the defined slot, for transmitting the further first message is based on the selected access opportunity configuration. [8] Method (100) according to claim 7, wherein the set of access opportunity configurations is preconfigured by the communication network (10) and / or depends on a type of wireless device (14a, 14b, 14c; 14). [9] Method (100) according to any of the preceding claims, wherein the access opportunity configuration is further selected by the wireless device (14a, 14b, 14c; 14) based on a received configuration message. [10] Method (100) according to any one of the preceding claims, further comprising: - Receiving, by the wireless device (14a, 14b, 14c; 14), a message transmitted by the node (12), wherein the message specifies a set of access opportunities, in particular a set of slots, and the further message can be transmitted by the wireless device (14a, 14b, 14c; 14) only in one of the access opportunities contained in the set. [11] Method (100) according to any one of the preceding claims, further comprising: - Receiving, by the wireless device (14a, 14b, 14c; 14), an access configuration message transmitted by the node (12) to configure the wireless device (14a, 14b, 14c; 14) to access the transmission medium of the communication network (10), wherein the access configuration message may specify the following: ◯ a number of access rounds per paging round, and / or ◯ a number of sets of access opportunities per access, and / or ◯ a number of access opportunities per set. [12] Method (100) according to any one of the preceding claims, further comprising: - Performing energy harvesting by the wireless device (14a, 14b, 14c; 14), based on the specified backoff condition, to increase the energy level of the device for transmitting the next first message. [13] 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 of the preceding claims. [14] Computer program comprising machine-readable instructions to cause the wireless device (14a, 14b, 14c; 14) according to claim 13 to execute the method (100) according to any one of claims 1 to 12. [15] Non-volatile, computer-readable medium on which the computer program according to claim 14 is stored.