Method(s)s for initiating a random access procedure of a wireless device in a communication network

Abstract

A method for initiating a random access procedure of a wireless device (14a, 14b, 14c; 14), preferably an ambient Internet of Things (IoT) device (14a, 14b, 14c; 14), in a communication network (10), the method (100) comprising: - Receiving, by the wireless device (14a, 14b, 14c; 14), a trigger message transmitted from a node (12) or a further node (16) of the communication network (10) for triggering the transmission of a first message of the random access procedure, - Determining, by the wireless device (14a, 14b, 14c; 14), in response to the received trigger message, whether a condition for transmitting the first message is fulfilled; and - Transmitting, by the wireless device (14a, 14b, 14c; 14), the first message to the node (12) based on a result of the determining, wherein the first message comprises a random value and / or a device identification information for requesting access to a transmission medium of the communication network (10), preferably for requesting transmission resources from the node (12).

Description

[0001] R. 416156

[0002] - 1 -

[0003] Specification

[0004] Title

[0005] Method(s)s for initiating a random access procedure of a wireless device in a communication network

[0006] The invention concerns two corresponding methods for initiating a random access procedure of a wireless device, preferably an ambient Internet of Things (loT) device, in a communication network. Further, the invention concerns a wireless device, preferably an ambient loT device, a node, a computer program and a non-transitory computer readable medium.

[0007] Background

[0008] The state of the art in ambient loT devices, as currently studied by 3GPP, encompasses low-complexity, low-energy demanding wireless devices designed for various use-cases, such as inventory management, localization, and sensor data exchange within indoor and outdoor environments. These wireless devices are categorized into three main groups, each with different power consumption and transmission characteristics.

[0009] Type 1 devices have a peak power consumption of approximately 1 pW, comprise an energy storage, and have an initial sampling frequency offset (SFO) of up to 10X ppm. They do not have amplification in the device for either downlink (DL) or uplink (UL) transmission, and their UL transmission is based on backscattering an externally provided carrier wave.

[0010] Type 2a and Type 2b devices have peak power consumption of a few hundred pW, comprise an energy storage, and have an initial SFO of up to 10X ppm. Both types have amplification for DL and / or UL transmission, with Type 2a devices generating UL transmissions by backscattering externally provided carrier waves and Type 2b devices generating UL transmission internally.

[0011] The ambient loT device may be configured to directly and bidirectionally communicate with a user equipment or a base station. The ambient loT device R. 416156

[0012] - 2 - may also be configured to indirectly and bidirectionally communicate with a base station via at least one intermediate node, e.g., a user equipment (UE) or a reader or a relay.

[0013] The ambient loT device may also be configured for receiving downlink transmissions directly from a base station, and for receiving uplinks transmissions to the base station via at least one assisting node. The ambient loT device may alternatively be configured for receiving downlink transmission from the base stations via at least one assisting node, and for transmitting uplinks transmissions directly to the base station.

[0014] The random access procedure for these ambient loT devices may be based on a slotted ALOHA Medium Access (MAC) protocol, where devices access the channel only at the start of a time slot when triggered by the network. In the event of a collision, a resolution mechanism is required to address the simultaneous channel access by multiple ambient loT devices.

[0015] The random access procedure for ambient loT devices can be categorized based on the number of message exchanges and the approach to contention resolution: The procedure may be classified as two-step, three-step, or four-step, depending on the specific sequence of message exchanges involved in initiating and completing the random access process. Additionally, the procedure may be categorized as contention-based or contention-free, based on whether specific mechanisms are employed to mitigate contention and resolve collisions during channel access.

[0016] In conventional wireless networks with random access transmission, UEs transmit a random access preamble via the uplink random access channel. The network responds with a random access response. The U Es respond with a contention resolution identifier (CRID) to be 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.

[0017] Existing random access mechanism do not account for the characteristics and capabilities of ambient loT devices, e.g., limited or no energy storage, low power, energy harvesting operation. R. 416156

[0018] - 3 -

[0019] Disclosure of the invention

[0020] According to a first aspect, there is provided a method for initiating a random access procedure of a wireless device, preferably an ambient Internet of Things (loT) device, in a communication network.

[0021] The method according to the first aspect comprises:

[0022] Receiving, by the wireless device, a trigger message transmitted from a node or a further node of the communication network for triggering the transmission of a first message of the random access procedure, Determining, by the wireless device in response to the received trigger message, whether a condition for transmitting the first message is fulfilled; and

[0023] Transmitting, by the wireless device, the first message to the node based on a result of the determining, wherein the first message comprises a random value and / or a device identification information for requesting access to a transmission medium of the communication network, preferably for requesting transmission resources from the node.

[0024] The method according to the first aspect can be understood as a method for wireless communications, specifically of operating the wireless device, preferably the ambient loT device, of the communication network.

[0025] According to a second aspect, there is provided a method for initiating a random access procedure of a wireless device, preferably an ambient Internet of Things (loT) device, in a communication network.

[0026] The method according to the second aspect comprises:

[0027] Receiving, by a node of the communication network, a first message of the random access procedure transmitted from the wireless device in response to receiving a trigger message and based on a result of determining, by the wireless device, in response to the received trigger message, whether a condition for transmitting the first message is fulfilled, wherein the first message comprises a random value and / or a device identification information for requesting access to a transmission medium R. 416156

[0028] - 4 - of the communication network, preferably for requesting transmission resources from the node; and

[0029] Transmitting, by the node, a second message of the random access procedure to the wireless device in response to receiving the first message, wherein the second message comprises o the random value and / or the wireless device identification information comprised by the first message and / or o a resource information about transmission and / or retransmission resources allocated for the wireless device.

[0030] The method according to the second aspect can be understood as a method for communications, specifically of operating the node of the communication network.

[0031] According to a third aspect, there is provided a wireless device, preferably an ambient loT device, of a communication network. The wireless device is configured to execute the method according to the first aspect, or its embodiments.

[0032] According to a fourth aspect, there is provided a node, preferably a radio node, of a communication network. The node is configured to execute the method according to the second aspect, or its embodiments.

[0033] According to a fifth aspect, there is provided a computer program comprising machine-readable instructions to cause the wireless device as defined by the third aspect to execute the method according the first aspect, and / or its embodiments, and / or the node as defined by the fourth aspect to execute the method according the second aspect, and / or its embodiments.

[0034] According to a sixth aspect, there is provided a non-transitory computer readable medium having stored thereon the computer program as defined by the sixth aspect.

[0035] The communication network may comprise a wireless network and a core network. The communication network may be configured as a cellular network, R. 416156

[0036] - 5 - preferably according to 3GPP specifications, e.g., according to 3GPP release 18 or beyond, or as a wireless Local Area Network (LAN), preferably according to IEEE specifications. The communication network comprises at least the wireless device and the node.

[0037] The wireless device may be configured as a low-energy or low-power device. The wireless device may have a peak power consumption of less than 1 mW, preferably less than 500 pW, specifically less than 100 pW, according to an embodiment, less than 10 pW, e.g., approximately 1 pW.

[0038] The wireless device is preferably configured for energy harvesting, thus exploiting ambient energy sources, e.g., radio waves, thermal radiation, mechanical vibrations etc. as power supply. The wireless device may or may not comprise an energy storage, e.g., a battery.

[0039] Specifically, the wireless device is different from a Reduced Capability (Redcap) device, a narrow band loT (NB-loT) device, a device for enhanced machine-type communication (eMTC), e.g., due to its lower hardware complexity and / or lower costs, and / or smaller form factors. Additionally, a communication between the wireless device and the node may not be controlled by a Radio Resource Control (RRC) layer. Particularly, a Hybrid Automated Repeat Request (HARQ) procedure may not be deployed or deployable for the communication between the wireless device and the node.

[0040] The wireless device may be arranged on or part of an environmental sensor, e.g., deployed in smart buildings, industrial facilities, and urban infrastructure to enable environmental monitoring and control, a smart home device to enable remote monitoring and control of home environments for energy efficiency, security, and convenience, 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 the location and status of assets, vehicles, and inventory in logistics, transportation, and supply chain management applications, R. 416156

[0041] - 6 - an industrial loT sensor and / or actuator to enable monitoring and controlling machinery, equipment, and processes, a smart agriculture device to enable optimizing resource usage and improving crop yields, a smart city infrastructure unit to enable smart street lighting, traffic monitoring, waste management, public safety, and environmental monitoring.

[0042] The node of the communication network may be a radio or wireless node, or a core network node. The radio node may be a base station or a user equipment, e.g., configured as a reader for ambient loT devices, or a relay or an integrated access and backhaul (IAB).

[0043] The random access procedure preferably comprises 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.

[0044] The first message may comprise or consist of the random access preamble. The random access preamble may comprise a random number and / or a device identification information.

[0045] The second message may comprise of consist of the random access response. The random access response may be an echo of the random number and / or the device identification information comprised by the random access preamble.

[0046] Messages of the random access procedure transmitted between the node and the wireless device, i.e., messages transmitted from the wireless device and received by the node and / or messages transmitted from the node and received by the wireless device, may either be transmitted directly, specifically, on the physical random access channel (PRACH), or indirectly via an intermediate or assisting node of the communication network. As an example, a message received by the wireless device may be transmitted from a core node of the communication network via a radio node, e.g., a base station, of the communication network, to the wireless device, and vice versa. R. 416156

[0047] - 7 -

[0048] The proposed solution addresses the challenge of adapting random access procedures to the characteristics of wireless devices, particularly ambient loT devices. By incorporating condition-based determination, the initiation of the random access procedure is optimized based on the device's specific operational requirements. This adaptive approach ensures that the wireless device responds to trigger messages and transmits the first message in a manner aligned with its operational capabilities and resource needs. Overall, this enhances the efficiency and effectiveness of the random access procedure, thus contributing to improved resource utilization.

[0049] According to an embodiment of the first aspect, the condition is pre-configured or comprised by the received trigger message. The condition may be pre-configured within the wireless device's operational parameters. Alternatively, the condition may be dynamically included in the trigger message received from the communication network or any dedicated control message. The pre-configured condition allows for predetermined criteria, such as specific energy levels or buffer states, to be set within the device. On the other hand, the dynamic inclusion of conditions in the trigger message enables the network to communicate specific requirements or triggers tailored to the device's operational state. This embodiment offers versatility in determining the conditions for initiating the random access procedure.

[0050] According to an embodiment of the first aspect, the condition is a device-based condition regarding a state and / or an operating mode of the wireless device. The condition may be determined or defined based on specific operational characteristics of the device itself, and / or of the device’s current and / or predicted operating mode. By basing the condition on the device's internal state and / or operational mode, the initiation of the random access procedure is tailored to the device's specific capabilities and requirements, optimizing its interaction with the communication network.

[0051] According to an embodiment of the first aspect, the device-based condition regards an energy state of an energy storage of the wireless device, and / or a buffer state of a buffer of the wireless device, and / or a message state of messages contained in a / the buffer of the wireless device, and / or R. 416156

[0052] - 8 - a location of the wireless device, and / or an operating mode of the wireless device.

[0053] The condition may be based on the energy state of the device's energy storage. For instance, the device may initiate the random access procedure when its energy level is above a (pre-) configurable or defined threshold, ensuring that it has sufficient power to engage in communication activities. The device may refrain from initiating the random access procedure when its energy level is below the (pre-) configurable or defined threshold.

[0054] The condition may be based on the buffer state of the device, indicating a fill level of the buffer and / or a number of messages stored in its buffer, and / or a type of message in the buffer, and / or requirements of message in the buffer, and / or a priority of messages in the buffer. For example, the device may refrain from initiating the random access procedure when a fill level of the buffer is below a (pre-) configurable or defined threshold. The device may initiate the random access procedure when the fill level of the buffer is above the (pre-) configurable or defined threshold.

[0055] The condition may be based on the state, e.g., an urgency and / or a packet delay and / or priority and / or an accumulation of a specific type, of (individual) messages contained in the device's buffer. For example, the device may refrain from initiating the random access procedure when a packet delay of the messages in the buffer is below a (pre-) configurable or defined threshold. The device may initiate the random access procedure when the packet delay is above the (pre-) configurable or defined threshold.

[0056] The condition may be based on a location of the wireless device, e.g., whether the device is located inside or outside of a predetermined zone or area. The device may initiate the random access procedure when it’s located inside or outside the zone, and may refrain from initiating the random access procedure when it is located outside or inside the zone.

[0057] The condition may be based on an operating or operation mode of the wireless device. The operating or operation mode may be a transmission mode or an energy harvesting mode. For example, the device may refrain from initiating the random access procedure when it is in the energy harvesting mode. The device may initiate the random access procedure when it is in transmission mode. R. 416156

[0058] - 9 -

[0059] In other words, the device-based condition may be an energy condition representing a relation between an energy level of the wireless device and a corresponding energy threshold, and / or a buffer condition representing a relation between a number and / or a delay of messages in a buffer of the wireless device and (a) corresponding threshold(s), and / or a message condition representing a relation between a number and / or a delay of messages in a buffer of the wireless device and (a) corresponding threshold(s), a location condition representing a relation between the location of the wireless device and a predetermined zone, and / or an operating mode condition representing a relation between an actual or current operating mode of the wireless device and a target operating mode.

[0060] By incorporating these device-based conditions, the random access procedure is intelligently linked to the device's internal state and operational requirements, allowing for efficient and context-aware initiation of communication activities within the network.

[0061] According to an embodiment of the first aspect, the device-based condition regards an energy harvesting operating mode of the wireless device. The condition for transmitting the first message may, e.g., be that the device is not in the harvesting operating mode or will not be in the harvesting operating mode for a specific number of upcoming slots. The device may refrain from initiating the random access process if the device is in the energy harvesting operating mode. For example, if the device is actively harvesting energy from its environment or is expected to do so for a predetermined duration, it may delay the initiation of the random access procedure for a defined period or number of slots. By incorporating this condition, the wireless device optimizes its communication activities based on its energy harvesting operational mode, ensuring that the random access procedure is initiated at an opportune time when energy resources are readily available and stable.

[0062] According to an embodiment of the first aspect, the method further comprises: Receiving, by the wireless device, a second message transmitted from the node in response to receiving the first message, R. 416156

[0063] - 10 - wherein the second message comprises o the random value and / or the wireless device identification information comprised by the first message and / or o a resource information about transmission and / or retransmission resources allocated for the wireless device.

[0064] The second message may the random access response. The second message may comprise an echo of the random number and / or the device identification information. The second message may additionally or alternatively indicate transmission resources of the network allocated for a transmission or a or multiple retransmission(s) of the wireless device. The resource information may indicate, e.g., a slot or a set of slots allocated for a transmission or retransmission of the wireless device. Further, the second message may comprise control information.

[0065] This allows for efficient signaling the wireless device to continue with step three of a three / four step random access procedure or to start with payload transmission in a two step random access procedure.

[0066] According to an embodiment of the first aspect, the method further comprises: Transmitting, by the wireless device, in response to receiving the second message, a third message to the node, preferably using the allocated transmission resources, wherein the third message comprises a / the device identification information and / or data.

[0067] The third message may be a third message of the random access procedure. The third message preferably (only) comprises the device identification in case the first message does not comprise the device identification. The third message may also be a payload transmission. This allows the wireless device to effectively utilize the allocated transmission resources by transmitting data or device identification information.

[0068] According to an embodiment of the second aspect, the method comprises: Transmitting, by the node, a trigger message to the wireless device o for triggering the transmission of the first message of the random access procedure, and, o optionally, to at least one further wireless device of the communication network for triggering the transmission of a further R. 416156

[0069] - 11 - first message of a random access procedure of the at least one further wireless device, wherein the at least one further wireless device is located in a zone comprising the wireless device.

[0070] The trigger message may part of a paging message transmitted over a paging channel of the communication network. For example, the trigger message may be transmitted, by the node, to all wireless devices, e.g., of a specific device type of category, within the zone. The zone may be a spatial zone of predetermined shape and / or size.

[0071] For example, in a wireless network, the trigger message may be transmitted by base station to an ambient loT device, prompting the device to initiate the random access procedure. Additionally, the trigger message may also be transmitted to other ambient loT devices located within the same coverage area or zone, ensuring coordinated initiation of the random access procedure for devices within the designated zone.

[0072] This allows for an efficient and coordinated initiation of the random access procedure, thus reducing collisions and contention with other devices attempting to access the network. Further, this embodiment facilitates the synchronized initiation of the random access procedure for multiple wireless devices within a specific zone, ensuring efficient and coordinated access to the communication network.

[0073] According to an embodiment of the second aspect, the method comprises: Receiving, by a node of the communication network, a / the further first message of a / the random access procedure transmitted from a / the further wireless device of the communication network; and Performing contention resolution based on the received first and further first message, wherein the second message is transmitted based on a result of the contention resolution.

[0074] The result of the contention resolution may a random number and / or a device identification information winning the contention. By performing contention resolution access requests from multiple wireless devices within the communication network may be managed effectively. R. 416156

[0075] - 12 -

[0076] According to an embodiment of the second aspect, in the step of performing channel contention, the wireless device is selected for obtaining access to the transmission medium based on at least one of: the random value(s) contained in the first and / or the further first message; additional information comprised by the first and / or the further first message; a priority assigned to the wireless device and / or to a / the spatial zone comprising the wireless device.

[0077] The additional information could include device-specific parameters and / or requirements and / or message priorities and / or other relevant data that aids in the contention decision. The priority assigned to the spatial zone comprising the wireless device may also impact the contention resolution. For instance, if the device is located in a zone with higher priority, it may be given precedence in accessing the transmission medium. This allows for a fair and efficient access to the transmission medium, taking into account the specific characteristics and requirements of the wireless devices within the network.

[0078] According to a further aspect of the invention, there is provided a (wireless) communication network comprising at least the wireless device and the node.

[0079] According to a further aspect of the invention, there is provided a method of operating the communication network. The method of 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.

[0080] The non-transitory computer readable medium is preferably configured 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- transitory computer readable media may include RAM, ROM, EEPROM, and any other non-volatile storage device.

[0081] Description of the figures

[0082] Exemplary embodiments of the present invention are depicted in the figures, which are not to be construed as limiting the claims, and are explained in greater detail below. R. 416156

[0083] - 13 -

[0084] Fig. 1 schematically illustrates a communication network according to an embodiment of the invention;

[0085] Fig. 2A,B schematically illustrate methods according to embodiments of the invention; and

[0086] Fig. 3 schematically illustrates a method according to a further embodiment of the invention.

[0087] Fig. 1 schematically illustrates a communication network 10 according to an 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 may comprise a core network and a wireless network.

[0088] The communication network 10 comprises a radio node 12, configured as a user equipment 12, or a reader 12 for an ambient Internet of Things (loT) device, or a relay node acting as a reader, and a plurality of wireless devices 14a, 14b, 14c, preferably configured as ambient loT devices 14a, 14b, 14c, specifically according to 3GPP specifications. The wireless devices 14a, 14b, 14c are collectively represented by reference sign 14. The communication network 10 further comprises a radio node 16 configured as a base station 16.

[0089] For requesting access to a transmission medium of the communication network 10, the wireless devices 14 are configured to perform a method for initiating a preferably slot-based random access procedure. Here, the random access procedure may be based on a slotted ALOHA random access MAC protocol. I.e., the wireless devices 14 are configured to begin a transmission only at the beginning of a slot. The length of the slot preferably equals the sum of a packet transmission time and a maximum propagation delay in the network to ensure that both transmission and reception of a data packet can be completed within one slot.

[0090] The random access procedure may be established between the respective wireless device 14a, 14b, 14c and the reader 12, or between the respective wireless device 14a, 14b, 14c and the base station 16. For the latter case, R. 416156

[0091] - 14 - transmission between the wireless devices 14 and the base station 16 may be routed or relayed via the reader 12.

[0092] According to an alternative embodiment, the base station 16 may be configured as a reader for the wireless devices 14. Consequently, 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).

[0093] The wireless devices 14 are configured for initiating a random access procedure of the respective wireless device 14a, 14b, 14c by performing the method according to the first aspect of the invention, and / or its embodiments, as further described in Fig. 2A.

[0094] The node 12 and / or the node 16 are configured for initiating a random access procedure of the at least one of the wireless device 14a, 14b, 14c by performing the method according to the second aspect of the invention, and / or its embodiments, as further described in Fig. 2B.

[0095] Fig. 2 schematically illustrates two methods according to embodiments of the invention.

[0096] Fig. 2A schematically illustrates a method 100 for initiating a random access procedure of a wireless device 14a, preferably an ambient Internet of Things (loT) device, in a communication network, e.g., the communication network 10 of Fig. 1.

[0097] The method 100 comprises a step 110 of receiving, by the wireless device 14a, a trigger message transmitted from a node 12 or a further node 16 of the communication network for triggering the transmission of a first message of the random access procedure.

[0098] The method 100 comprises a step 120 of determining, by the wireless device 14a, in response to the received trigger message, whether a condition for transmitting the first message is fulfilled.

[0099] The method 100 comprises a step 130 of transmitting, by the wireless device 14a, the first message to the node 12 based on a result of the determining. The first message comprises a random value and / or a device identification R. 416156

[0100] - 15 - information for requesting access to a transmission medium of the communication network, preferably for requesting transmission resources from the node 12. The first message may be configured as a random access preamble.

[0101] The method may comprise an optional step 140 of receiving, by the wireless device 14a, a second message transmitted from the node 12 in response to receiving the first message, wherein the second message comprises

[0102] - the random value and / or the wireless device identification information comprised by the first message and / or

[0103] - a resource information about transmission and / or retransmission resources allocated for the wireless device.

[0104] The first message may be configured as a random access response.

[0105] The method may comprise an optional step 150 of transmitting, by the wireless device 14a, in response to receiving the second message, a third message of the random access procedure and / or a further message to the node 12, preferably using the allocated transmission resources.

[0106] Fig. 2B schematically illustrates a method 200 for initiating a random access procedure of a wireless device 14a, preferably an ambient Internet of Things (loT) device, in a communication network.

[0107] The method 200 may comprise an optional step 210 of transmitting, by a node 12 of the communication network, a trigger message to the wireless device 14a for triggering the transmission of the first message of the random access procedure, and, optionally, to at least one further wireless device 14b of the communication network for triggering the transmission of a further first message of a random access procedure of the at least one further wireless device 14b.

[0108] Here, the at least one further wireless device 14b is located in a zone comprising the wireless device 14a.

[0109] The method 200 comprises a step 220 of receiving, by the 12, the first message of the random access procedure transmitted from the wireless device 14 in R. 416156

[0110] - 16 - response to receiving a trigger message and based on a result of determining, by the wireless device 14, in response to the received trigger message, whether a condition for transmitting the first message is fulfilled. The first message comprises a random value and / or a device identification information for requesting access to a transmission medium of the communication network, preferably for requesting transmission resources from the node 12.

[0111] The method 200 may further comprise an optional step 230 of

[0112] Receiving, by the node 12, the further first message of the random access procedure transmitted from the further wireless device 14b of the communication network.

[0113] The method 200 may further comprise an optional step 240 of Performing contention resolution, by the node 12, based on the received first and further first message.

[0114] The method 200 comprises a step 250 of transmitting, by the node 12, a second message of the random access procedure to the wireless device 14a in response to receiving the first message, preferably further in response on receiving the further first message and based on a result of the contention resolution. The second message comprises the random value and / or the wireless device identification information comprised by the first message and / or a resource information about transmission and / or retransmission resources allocated for the wireless device 14a.

[0115] Fig. 3 schematically illustrates a method 300 for performing a random access procedure of a an ambient loT device, in a communication network 10 according to a further embodiment of the invention. The method 300 can be understood as an enhancement of known random access procedures to trigger an ambient loT device or a set of ambient loT devices to start random access and data transmission or data retransmission.

[0116] In step 310, a standardized trigger preamble set upon reception of control messages from network for e.g., core network or from application layer, is generated by a radio node of the network. The radio node may be a carrier-wave emitter or a reader of ambient loT devices, e.g., a specific reader device, or a R. 416156

[0117] - 17 - user equipment with ambient loT capability or a relay or a subnetwork management entity.

[0118] In step 320, a trigger message consisting of or containing the trigger preamble is sent, by the radio node, as unicast or multicast or groupcast or broadcast to the device or the set of devices. As an alternative, the trigging message can also be sent, by the radio node, based on a predefined or indicated zone where the ambient loT devices are located. In this case, all devices located in the indicated zone are triggered for random access mechanism based on reception of the trigger message.

[0119] The trigger message or trigger preambles are transmitted periodically with a specified rate or based on signaling received, by the radio node, from the network, e.g., from the core network or from higher layers e.g., from the application layer.

[0120] In step 320, the trigger message is received, by the ambient loT device(s), i.e., the ambient loT device(s) are triggered (conditional paging) to start a random access procedure.

[0121] The start of random access procedure is based on checking a condition for transmitting a first message of the random access procedure. Here, the start of the random access procedure may be based on a set of configured or preconfigured conditions. The condition may regard, e.g., a number of existing messages in a buffer of device, and / or a sufficiency of a current energy level for transmission of data, e.g., for transmission of a specific number of messages in the buffer, and / or a harvesting time (ignore paging and continue paging to reach specific energy threshold) and / or packet delay budget (keep message in buffer as long as packet delay is below threshold).

[0122] In step 330, in a three or four step random access procedure, a random number or random value is generated by the ambient loT device(s). In a two step random access procedure, a random number / value and at least one of a device identifier and upper layer data is determined for participating in a contention for accessing a channel or transmission medium of the communication network. The random value can have fixed or variable size. The random value can be fully random or influenced by several parameters such as remaining energy, and / or R. 416156

[0123] - 18 - priority of messages or message requirements such as latency or packet delay budget, and / or be repeated from a prior round of random access channel contention.

[0124] In step 340, the random value, or the random value and additional information like the device identifier and / or status information and / or the upper layer data, is sent, by the ambient loT device(s), to the radio node. Here, the sent information is preferably comprised by a message, specially a first message of the random access procedure, e.g., a random access preamble. The message is transmitted at some point in time, e.g., at the start of a slot in case of a slotted-ALOHA random access or at the start of a time window defined for channel contention by the reader or the network.

[0125] In step 350, the random value of at least one device is received and decoded at the reader (successfully).

[0126] In step 360, based on the received random value from the ambient loT device(s), channel contention resolution is performed by the reader to select an ambient loT device for channel access. The selection of devices by the reader could be

[0127] - fully random, and / or

[0128] - based the random value, and / or

[0129] - based on some additional information explicitly modulated in the random value signal, and / or

[0130] - based on the priority of the ambient loT device(s) and / or a priority of the zone where the set of ambient loT device(s) is located, and / or

[0131] - based on conditions defined by higher layers or the network.

[0132] In step 370, the same random value or some additional information is sent back to the ambient loT device(s) by the reader.

[0133] Here, along with the random value sent back to the device(s) by the reader, a transmission of upcoming message(s) may also be scheduled by the reader. To this end, transmission resources may be indicated by the reader to provide the possibility of contention free transmission(s) by the device(s). In addition, one or several further message from the ambient loT device to the reader may be scheduled, by the reader, to help the device(s) to avoid contention and random R. 416156

[0134] - 19 - access in the future. Besides, multiple resource may be scheduled for the device for retransmissions to enhance the reliability of communication.

[0135] The scheduled transmission resources, specifically the scheduled time slot(s) can be used, by the wireless device, for transmission of control messages, and / or for transmission of buffered messages in a buffer of the device(s), and / or for retransmission of buffered messages in a / the buffer of the device(s) to increase a reliability of the message transmission, and / or for purposeful retransmissions for increasing reliability.

[0136] Here, the scheduling of the one or several further messages may be based on set of pre-requirements or conditions.

[0137] In step 380, the information / message transmitted in step 370 is received by the ambient loT device. In other words, the device receives the same random value it generated in step 330.

[0138] In step 390, a next message, preferably a third message, of the random access procedure may be transmitted by the device. The message may be transmitted with or without contention. The message may be transmitted in a next slot in case of a slotted-ALOHA random access procedure, or in a time slot scheduled by the reader. The scheduled time slot or the allocated radio resource(s) can be conveyed to the device, alongside the second or fourth message of the random access procedure or over a control channel in a different frequency slot, e.g., over a downlink channel. Prior to initiating or starting a transmission of a buffered message in the following or scheduled time slot, the identifier of the device may be transmitted to the reader.

[0139] In an optional step 400, an acknowledgement for successful reception of the device identifier and / or the buffered message(s) may be transmitted, by the reader, to the device.

Claims

R. 416156- 20 -Claims1 . A method (100) for initiating a random access procedure of a wireless device (14a, 14b, 14c; 14), preferably an ambient Internet of Things (loT) device (14a, 14b, 14c; 14), in a communication network (10), the method (100) comprising:Receiving (110), by the wireless device (14a, 14b, 14c; 14), a trigger message transmitted from a node (12) or a further node (16) of the communication network (10) for triggering the transmission of a first message of the random access procedure,Determining (120), by the wireless device (14a, 14b, 14c; 14), in response to the received trigger message, whether a condition for transmitting the first message is fulfilled; andTransmitting (130), by the wireless device (14a, 14b, 14c; 14), the first message to the node (12) based on a result of the determining (120), wherein the first message comprises a random value and / or a device identification information for requesting access to a transmission medium of the communication network (10), preferably for requesting transmission resources from the node (12).

2. The method (100) according to claim 1 , wherein the condition is preconfigured or comprised by the received trigger message.

3. The method (100) according to claim 1 or 2, wherein the condition is a device-based condition regarding a state and / or an operating mode of the wireless device (14a, 14b, 14c; 14).

4. The method (100) according to claim 3, wherein the device-based condition regards an energy state of an energy storage of the wireless device (14a, 14b, 14c; 14), and / or a buffer state of a buffer of the wireless device (14a, 14b, 14c; 14), and / or a message state of messages contained in a / the buffer of the wireless device (14a, 14b, 14c; 14), and / or a location of the wireless device (14a, 14b, 14c; 14), and / orR. 416156- 21 - an operating mode of the wireless device (14a, 14b, 14c; 14).

5. The method (100) according to claim 3 or 4, wherein the device-based condition regards an energy harvesting operating mode of the wireless device (14a, 14b, 14c; 14).

6. The method (100) according to one of the preceding claims, further comprising:Receiving (140), by the wireless device (14a, 14b, 14c; 14), a second message transmitted from the node (12) in response to receiving the first message, wherein the second message comprises o the random value and / or the wireless device (14a, 14b, 14c; 14) identification information comprised by the first message and / or o a resource information about transmission and / or retransmission resources allocated for the wireless device (14a, 14b, 14c; 14).

7. The method (100) according to claim 6, further comprising:Transmitting (150), by the wireless device (14a, 14b, 14c; 14), in response to receiving (140) the second message, a third message to the node (12), preferably using the allocated transmission resources, wherein the third message comprises a / the device identification information and / or data.

8. A method (200) for initiating a random access procedure of a wireless device (14a, 14b, 14c; 14), preferably an ambient Internet of Things (loT) device (14a, 14b, 14c; 14), in a communication network (10), the method (200) comprising:Receiving (220), by a node (12) of the communication network (10), a first message of the random access procedure transmitted from the wireless device (14a, 14b, 14c; 14) in response to receiving a trigger message and based on a result of determining, by the wireless device (14a, 14b, 14c; 14), in response to the received trigger message, whether a condition for transmitting the first message is fulfilled, wherein the first message comprises a random value and / or a device (14a, 14b, 14c; 14) identification information for requesting access to a transmission medium of the communication network (10), preferably for requesting transmission resources from the node (12); andR. 416156- 22 -Transmitting (250), by the node (12), a second message of the random access procedure to the wireless device (14a, 14b, 14c; 14) in response to receiving the first message, wherein the second message comprises o the random value and / or the wireless device (14a, 14b, 14c; 14) identification information comprised by the first message and / or o a resource information about transmission and / or retransmission resources allocated for the wireless device (14a, 14b, 14c; 14).

9. The method (200) according to claim 8, further comprising:Transmitting (210), by the node (12), a trigger message to the wireless device (14a, 14b, 14c; 14) o for triggering the transmission of the first message of the random access procedure, and, o optionally, to at least one further wireless device (14a, 14b, 14c;14) of the communication network (10) for triggering the transmission of a further first message of a random access procedure of the at least one further wireless device (14a, 14b, 14c; 14), wherein the at least one further wireless device (14a, 14b, 14c;14) is located in a zone comprising the wireless device (14a, 14b, 14c; 14).

10. The method (200) according to claim 8 or 9, further comprising:Receiving (230), by a node (12) of the communication network (10), a / the further first message of a / the random access procedure transmitted from a / the further wireless device (14a, 14b, 14c; 14) of the communication network (10); andPerforming (240) contention resolution based on the received first and further first message, wherein the second message is transmitted based on a result of the contention resolution.11 . The method (200) according to claim 10, wherein in the step of performing channel contention the wireless device (14a, 14b, 14c; 14) is selected for obtaining access to the transmission medium based on at least one of: the random value(s) contained in the first and / or the further first message;R. 416156- 23 - additional information comprised by the first and / or the further first message; a priority assigned to the wireless device (14a, 14b, 14c; 14) and / or to a / the spatial zone comprising the wireless device (14a, 14b, 14c; 14).

12. A wireless device (14a, 14b, 14c; 14) of a communication network (10) configured to execute the method (100) according to one of claims 1 to 7.

13. A node (12) of a communication network (10) configured to execute the method (200) according to one of claims 8 to 11 .

14. A computer program comprising machine-readable instructions to cause the wireless device (14a, 14b, 14c; 14) according to claim 15 to execute the method (100) according to one of claims 1 to 7, and / or the node (12) according to claim 16 to execute the method (200) according to one of claims 8 to 11.

15. A non-transitory computer readable medium having stored thereon the computer program according to claim 14.

Images