Terminal device assistance information

Abstract

A method, apparatus, and computer program are described comprising: receiving, at a terminal device from a network node of a mobile communications network, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; performing, by the terminal device, at least one RACH procedure; and sending, from the terminal device to the network node, information associated with the at least one RACH procedure based at least in part on the configuration.

Description

[0001] TERMINAL DEVICE ASSISTANCE INFORMATION

[0002] Field

[0003] Example embodiments may relate to terminal devices, network nodes, and methods for reporting information associated with RACH procedures.

[0004] Background

[0005] Radio Access Networks (RANs) rely on an allocation of spectrum, so that they may assign frequency resources to facilitate communication between network entities and terminal devices. When deploying a Radio Access Technology (RAT), there may be a shortage of unallocated spectrum in which the Radio Access Technology can operate. There is therefore an interest in providing methods supporting the dynamic sharing of spectrum between RATs. There may be an interest in providing methods by which terminal devices may provide information which may inform a dynamic allocation of spectrum.

[0006] Summary

[0007] The scope of protection sought for various embodiments of the invention is set out by the independent claims. The embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0008] A first aspect provides a terminal device comprising means for receiving from a network node of a mobile communications network a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; means for performing at least one RACH procedure; and means for sending to the network node information associated with the at least one RACH procedure based at least in part on the configuration.

[0009] In some example embodiments the at least one RACH procedure comprises: selecting a RACH preamble and RACH occasion, and performing at least one RACH attempt, wherein respective RACH attempts of the at least one RACH attemptcomprise transmitting the selected preamble on the selected RACH occasion.

[0010] In some example embodiments the means for sending information is configured to send, based at least in part on the configuration, information indicative of at least one of: a number of RACH attempts performed by the terminal device; a number of RACH procedures performed by the terminal device that comprise performing a number of RACH attempts, and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; and a transmit power used by the terminal device to transmit the selected preamble during a RACH attempt.

[0011] In some example embodiments the configuration is indicative of a window; and the means for sending information is configured to send information associated with at least one event of the at least one RACH procedure based at least in part on the event occurring within the window.

[0012] In some example embodiments, the means for sending information is configured to send, based at least in part on the configuration, information indicative of a number of RACH attempts performed by the terminal device within the window indicated by the configuration.

[0013] In some example embodiments, the means for sending information is configured to send, based at least in part on the configuration, information indicative of a number of RACH procedures performed by the terminal device within the window that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0014] In some example embodiments, the means for sending information is configured to send, based at least in part on the configuration, information indicative of a RACH occasion used by the terminal device in a RACH procedure performed bythe terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0015] In some example embodiments, the means for sending information is configured to send, based at least in part on the configuration, information indicative of a RACH preamble used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0016] In some example embodiments, the means for sending information is configured to send, based at least in part on the configuration, information indicative of an SSB index mapped to at least one of a RACH preamble and a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0017] In some example embodiments, the means for sending information is configured to send, based at least in part on the configuration, information indicative of a transmit power used by the terminal device to transmit a RACH preamble in the most recent RACH attempt within the window.

[0018] In some example embodiments, the means for receiving the configuration is configured to receive the configuration via a system information broadcast by the network node.

[0019] In some example embodiments, the means for receiving the configuration is configured to receive the configuration via at least one of: RRC signaling; paging;and a physical downlink control channel, PDCCH, instruction to perform a RACH procedure.

[0020] In some example embodiments, the means for sending information is configured to send the information as part of the second uplink message of a four-step RACH procedure.

[0021] In some example embodiments, the means for sending information is configured to send the information as part of the first uplink message of a two-step RACH procedure.

[0022] A second aspect provides a method comprising: receiving, at a terminal device from a network node of a mobile communications network, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; performing, by the terminal device, at least one RACH procedure; and sending, from the terminal device to the network node, information associated with the at least one RACH procedure based at least in part on the configuration.

[0023] In some example embodiments the at least one RACH procedure comprises: selecting a RACH preamble and RACH occasion, and performing at least one RACH attempt, wherein respective RACH attempts of the at least one RACH attempt comprise transmitting the selected preamble on the selected RACH occasion.

[0024] In some example embodiments, sending information comprises sending, based at least in part on the configuration, information indicative of at least one of: a number of RACH attempts performed by the terminal device; a number of RACH procedures performed by the terminal device that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; and a transmit power used by the terminal device to transmit the selected preamble during a RACH attempt.In some example embodiments, the configuration is indicative of a window and sending information comprises sending information associated with at least one event of the at least one RACH procedure based at least in part on the event occurring within the window.

[0025] In some example embodiments, sending information comprises sending, based at least in part on the configuration, information indicative of a number of RACH attempts performed by the terminal device within the window indicated by the configuration.

[0026] In some example embodiments, sending information comprises sending, based at least in part on the configuration, information indicative of a number of RACH procedures performed by the terminal device within the window that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0027] In some example embodiments, sending information comprises sending, based at least in part on the configuration, information indicative of a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0028] In some example embodiments, sending information comprises sending, based at least in part on the configuration, information indicative of a RACH preamble used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving aresponse to the preamble transmission of a RACH attempt.

[0029] In some example embodiments, sending information comprises sending, based at least in part on the configuration, information indicative of an SSB index mapped to at least one of a RACH preamble and a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0030] In some example embodiments, sending information comprises sending, based at least in part on the configuration, information indicative of a transmit power used by the terminal device to transmit a RACH preamble in the most recent RACH attempt within the window.

[0031] In some example embodiments, receiving the configuration comprises receiving the configuration via a system information broadcast by the network node.

[0032] In some example embodiments, receiving the configuration comprises receiving the configuration via at least one of: RRC signaling; paging; and a physical downlink control channel, PDCCH, instruction to perform a RACH procedure.

[0033] In some example embodiments, sending information comprises sending the information as part of the second uplink message of a four-step RACH procedure.

[0034] In some example embodiments, sending information comprises sending the information as part of the first uplink message of a two-step RACH procedure.

[0035] A third aspect provides a computer program comprising instructions which, when executed by at least one processor, cause an apparatus to perform: receiving, at the apparatus from a network node of a mobile communications network, a configuration indicating random access channel, RACH, procedure information forreporting by the apparatus; performing, by the apparatus, at least one RACH procedure; and sending, from the apparatus to the network node, information associated with the at least one RACH procedure based at least in part on the configuration.

[0036] In some example embodiments, the third aspect may include any other feature mentioned with respect to the method of the second aspect.

[0037] A fourth aspect provides a non-transitory computer-readable medium having instructions stored thereon, which, when executed by at least one processor, cause an apparatus to perform: receiving, at the apparatus from a network node of a mobile communications network, a configuration indicating random access channel, RACH, procedure information for reporting by the apparatus; performing, by the apparatus, at least one RACH procedure; and sending, from the apparatus to the network node, information associated with the at least one RACH procedure based at least in part on the configuration.

[0038] The fourth aspect may include any other feature mentioned with respect to the method of the second aspect.

[0039] A fifth aspect provides an apparatus, the apparatus having at least one processor and at least one memory having instructions stored thereon which, when executed by the at least one processor, cause the apparatus to perform: receiving, at the apparatus from a network node of a mobile communications network, a configuration indicating random access channel, RACH, procedure information for reporting by the apparatus; performing, by the apparatus, at least one RACH procedure; and sending, from the apparatus to the network node, information associated with the at least one RACH procedure based at least in part on the configuration.

[0040] The fifth aspect may include any other feature mentioned with respect to the method of the second aspect.A sixth aspect provides a network node comprising: means for sending, to a terminal device, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; and means for receiving from the terminal device information associated with at least one RACH procedure performed by the terminal device.

[0041] In some example embodiments the at least one RACH procedure comprises: selecting a RACH preamble and RACH occasion, and performing at least one RACH attempt, wherein respective RACH attempts of the at least one RACH attempt comprise transmitting the selected preamble on the selected RACH occasion.

[0042] In some example embodiments, the means for receiving information is configured to receive information indicative of at least one of: a number of RACH attempts performed by the terminal device; a number of RACH procedures performed by the terminal device that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; and a transmit power used by the terminal device to transmit the selected preamble during a RACH attempt.

[0043] In some example embodiments, the configuration is indicative of a window, and the means for receiving information is configured to receive information associated with at least one event of the at least one RACH procedure, the event having occurred within the window.

[0044] In some example embodiments, the means for receiving information is configured to receive information indicative of a number of RACH attempts performed by the terminal device within the window indicated by the configuration.

[0045] In some example embodiments, the means for receiving information is configured to receive information indicative of a number of RACH procedures performed by the terminal device within the window that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number ofRACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0046] In some example embodiments, the means for receiving information is configured to receive information indicative of a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0047] In some example embodiments, the means for receiving information is configured to receive information indicative of a RACH preamble used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0048] In some example embodiments, the means for receiving information is configured to receive information indicative of an SSB index mapped to at least one of a RACH preamble and a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0049] In some example embodiments, the means for receiving information is configured to receive information indicative of a transmit power used by the terminal device to transmit a RACH preamble in the most recent RACH attempt within the window.

[0050] In some example embodiments, the means for sending the configuration isconfigured to send the configuration via a system information broadcast by the network node.

[0051] In some example embodiments, the means for sending the configuration is configured to send the configuration via at least one of: RRC signaling; paging; and a physical downlink control channel, PDCCH, instruction to perform a RACH procedure.

[0052] In some example embodiments, the means for receiving the information is configured to receive the information as part of the second uplink message of a four-step RACH procedure.

[0053] In some example embodiments, the means for receiving the information is configured to receive the information as part of the first uplink message of a two-step RACH procedure.

[0054] A seventh aspect provides a method comprising: sending, from a network node to a terminal device, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; and receiving, at the network node from the terminal device, information associated with at least one RACH procedure performed by the terminal device.

[0055] In some example embodiments, receiving information comprises receiving information indicative of at least one of: a number of RACH attempts performed by the terminal device; a number of RACH procedures performed by the terminal device that comprise performing a number of RACH attempts and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; and a transmit power used by the terminal device to transmit the selected preamble during a RACH attempt.

[0056] In some example embodiments, the configuration is indicative of a window; and receiving information comprises receiving information associated with at least oneevent of the at least one RACH procedure, the event having occurred within the window.

[0057] In some example embodiments, receiving information comprises receiving information indicative of a number of RACH attempts performed by the terminal device within the window indicated by the configuration.

[0058] In some example embodiments, receiving information comprises receiving information indicative of a number of RACH procedures performed by the terminal device within the window that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0059] In some example embodiments, receiving information comprises receiving information indicative of a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0060] In some example embodiments, receiving information comprises receiving information indicative of a RACH preamble used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0061] In some example embodiments, receiving information comprises receiving information indicative of an SSB index mapped to at least one of a RACH preamble and a RACH occasion used by the terminal device in a RACH procedure performedby the terminal device within the window and that comprises: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0062] In some example embodiments, receiving information comprises receiving information indicative of a transmit power used by the terminal device to transmit a RACH preamble in the most recent RACH attempt within the window.

[0063] In some example embodiments, sending the configuration comprises sending the configuration via a system information broadcast by the network node.

[0064] In some example embodiments, sending the configuration comprises sending the configuration via at least one of: RRC signaling; paging; and a physical downlink control channel, PDCCH, instruction to perform a RACH procedure.

[0065] In some example embodiments, receiving the information comprises receiving the information as part of the second uplink message of a four-step RACH procedure.

[0066] In some example embodiments, receiving the information comprises receiving the information as part of the first uplink message of a two-step RACH procedure.

[0067] An eighth aspect provides a computer program comprising instructions which, when executed by at least one processor, cause an apparatus to perform: sending, from the apparatus to a terminal device, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; and receiving, at the apparatus from the terminal device, information associated with at least one RACH procedure performed by the terminal device.

[0068] In some example embodiments, the eighth aspect may include any other feature mentioned with respect to the method of the seventh aspect.A ninth aspect provides a non-transitory computer-readable medium having instructions stored thereon, which, when executed by at least one processor, cause an apparatus to perform: sending, from the apparatus to a terminal device, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; and receiving, at the apparatus from the terminal device, information associated with at least one RACH procedure performed by the terminal device.

[0069] The ninth aspect may include any other feature mentioned with respect to the method of the seventh aspect.

[0070] A tenth aspect provides an apparatus, the apparatus having at least one processor and at least one memory having instructions stored thereon which, when executed by the at least one processor, cause the apparatus to perform: sending, from the apparatus to a terminal device, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; and receiving, at the apparatus from the terminal device, information associated with at least one RACH procedure performed by the terminal device.

[0071] The tenth aspect may include any other feature mentioned with respect to the method of the seventh aspect.

[0072] Brief Description of the Drawings

[0073] Example embodiments will now be described by way of non-limiting example, with reference to the accompanying drawings, in which:

[0074] Fig. 1 illustrates an example of a communication system to which examples disclosed herein may be applied;

[0075] Fig. 2 is a schematic diagram illustrating a system implementing MRSS in accordance with example embodiments;

[0076] Fig. 3 is a schematic diagram illustrating an example partition of RACH resources in accordance with example embodiments;Fig. 4 is a flow diagram of a portion of a RACH procedure in accordance with example embodiments;

[0077] Fig. 5 is a signaling diagram of a method in accordance with example embodiments;

[0078] Fig. 6 is a flow diagram of a method in accordance with example embodiments; Fig. 7 is a flow diagram of a method in accordance with example embodiments; Fig. 8 is a schematic diagram of a system that may be used to implement one or more of the example embodiments; and

[0079] Fig. 9 shows tangible media for storing computer-readable code which when run by a computer may perform methods according to example embodiments described herein.

[0080] Detailed Description

[0081] The following embodiments are exemplary. Although the specification may refer to "an", "one", or "some" embodiment(s) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiment(s), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. Further, when a particular feature, structure, or characteristic is described in connection of an embodiment, it is within the knowledge of one skilled in the art to apply such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. It shall be understood that although the terms "first," "second" and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another.

[0082] For the purposes of the present disclosure, the phrases "at least one of A or B", "at least one of A and B", and "A and / or B" means (A), (B), or (A and B). For the purposes of the present disclosure, the phrase "A, B, and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C).

[0083] Embodiments described may be implemented in a communication system, suchas any of the following radio access technologies (RATs): World-wide Interoperability for Micro-wave Access (WiMAX), Global System for Mobile communications (GSM, 2G), GSM EDGE radio access Network (GERAN), General Packet Radio Service (GRPS), Universal Mobile Telecommunication System (UMTS, 3G) based on basic wideband-code division multiple access (W-CDMA), high-speed packet access (HSPA), Long Term Evolution (LTE), LTE-Advanced, and enhanced LTE (eLTE), 5G (also called NR), or any future RAT such as 6G. Moreover, communication within the communication system may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Frequency Division Duplexing (FDD), Time Division Duplexing (TDD), Multiple-Input Multiple-Output (MIMO), Orthogonal Frequency Division Multiplexing (OFDM), and / or Discrete Fourier Transform spread OFDM (DFT-s-OFDM).

[0084] As used herein, the term "network device" or "network node" refers to a node in a communication system via which user equipment may access the network and / or which is capable of controlling radio communication and managing radio resources within a cell. The network node or network device may be referred to as a base station (BS), an access point (AP) or an access node. The network device may be, depending on the applied technology, for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), an NR NB (also referred to as a gNB), a Remote Radio Unit (RRU), a radio head (RH), a remote radio head (RRH), a relay, an Integrated Access and Backhaul (IAB) node, a low power node, a nonterrestrial network (NTN) node or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, or an aircraft network device.

[0085] Moreover, in connection of split radio access network (RAN), the network device may refer to a centralised unit (CU) of a base station and / or a distributed unit (DU) of a base station. An interface between CU and DU may be referred to as an Fl interface in NR. In the split RAN architecture, node operations may be carried out, at least partly, in the central / centralized unit, CU, (e.g. server, host or node)operationally coupled to the DU, (e.g. a radio head / node). One CU may control one or more DUs, acting at least as transmit / receive (Tx / Rx) nodes. In some embodiments, the DUs may comprise e.g. a radio link control (RLC), medium access control (MAC) layer and a physical (PHY) layer, whereas the CU may comprise the layers above RLC layer, such as a packet data convergence protocol (PDCP) layer, Service Data Application Protocol (SDAP) layer and a radio resource control (RRC) layer. Other functional splits are possible too. In practice, any processing task may be performed in either the CU and / or the DU and the boundary where the responsibility is shifted between the CU and the DU may depend on the applied implementation.

[0086] The term "terminal device" refers to any end device that may be capable of wireless communication. By way of example, a terminal device may be referred to as a communication device, user equipment (UE), a Subscriber Station (SS), or a Mobile Station (MS). The terminal device may include a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones a tablet, a wearable terminal device, a personal digital assistant (PDA), portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and play-back appliances, vehicle-mounted wireless terminal devices, USB dongles, an Internet of Things (loT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and / or other wireless devices operating in an industrial and / or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and / or industrial wireless networks, and the like.

[0087] A term "resource", as used herein, may refer to radio resources in time domain, in frequency domain, in space domain, and / or in code domain. Some examples of resources include e.g. a physical resource block (PRB), a radio frame, a subframe, a time slot, a subband, a frequency region, a sub-carrier, a beam, etc. The term "transmission" and / or "reception" may refer to wirelessly transmitting and / or receiving via a wireless propagation channel on radio resources.Fig. 1 illustrates an example of a communication system to which examples disclosed herein may be applied. The communication system or a cellular communication system may comprise a network node 110 providing one or more cells, such as cell 100, and a network node 112 providing one or more other cells, such as cell 102. Each cell may be, e.g., a macro cell, a micro cell, femto, or a pico cell, for example. The cell may define a coverage area or a service area of the corresponding access node.

[0088] The network node 110 may provide a user equipment (UE) 120 (one or more UEs) with wireless access to the communication system. The wireless access may comprise downlink (DL) communication from the network node to the UE 120 and uplink (UL) communication from the UE 120 to the network node. Examples of uplink channels comprise physical uplink control channel (PUCCH) for transmitting control information and physical uplink shared channel (PUSCH) for transmitting data towards the network. Examples of downlink channels comprise physical downlink control channel (PDCCH) for transmitting control information and physical downlink shared channel (PDSCH) for transmitting data towards the user equipment.

[0089] There may be a plurality of UEs 120, 122 in the system. Each of them may be served by the same or by different network nodes 110, 112. UE may be configured with dual connectivity (DC), wherein the UE, e.g. UE 120, may be connected to multiple network nodes 110, 112. The UEs 120, 122 may communicate with each other, in case device-to-device (D2D) communication interface is established between them via a so-called sidelink (SL). Such D2D communications may be referred to as machine-to-machine, peer-to-peer (P2P) communications, or vehicle-to-vehicle (V2V), for example.

[0090] In the case of multiple network nodes in the communication system, the network nodes may be connected to each other via an interface. LTE specifications call such an interface as X2 interface. An interface between an LTE node and a 5G node, or between two 5G nodes is called Xn interface.The network nodes 110 and 112 may be further connected via another interface to a core network 116 of the communication system. The LTE specifications specify the core network as an evolved packet core (EPC), and the core network may comprise e.g. a mobility management entity (MME) and a gateway node. The MME may handle mobility of terminal devices in a tracking area encompassing a plurality of cells and handle signalling connections between the terminal devices and the core network. The gateway node may handle data routing in the core network and to / from the terminal devices. The 5G specifications specify the core network as a 5G core (5GC). The 5G core may comprise e.g. an access and mobility management function (AMF) and a user plane function / gateway (UPF) and other functions. The AMF may handle termination of non-access stratum (NAS) signalling, NAS ciphering & integrity protection, registration management, connection management, mobility management, access authentication and authorization, security context management. The UPF node may support packet routing and forwarding, packet inspection and quality of service (QoS) handling, for example.

[0091] Multi- RAT Spectrum Sharing

[0092] Multi-RAT Spectrum Sharing (MRSS) allows cells operating using different radio access technologies (RATs) to share the same carrier(s). For example, MRSS may allow 5G NR (a 5G RAT) to share carriers with a 6G RAT, allowing for more convenient migration from 5G to 6G. For example, spectrum sharing may allow the network to serve 5G RAT capable but 6G RAT incapable terminal devices using a 5G RAT, and serve 6G capable terminal devices using a 6G RAT, without the allocation of additional resources. Dynamic spectrum sharing may allow the network to adapt to long- and short-term changes in the populations of 6G RAT capable and 5G RAT capable, 6G RAT incapable devices attempting to access the network at the per-cell level.

[0093] Fig. 2 is a schematic diagram illustrating a system implementing MRSS, designated generally by reference numeral 200.In system 200, a 5G cell (served by 5G gNB 210) and a 6G cell (served by 6G NB 230) share the same radio unit (RU) 230. The 5G and 6G cells may have the same or similar coverage. A UE may connect to the 5G cell or the 6G cell via RU 230. An MRSS cell may therefore serve 6G capable UEs and legacy 5G UEs.

[0094] To use the spectrum effectively, it is desirable for the spectrum sharing between 5G and 6G RATs to be dynamic. To fully exploit dynamic sharing, a fast and reliable coordination between 5G RAN and 6G RAN is desirable. Different deployments can be expected for 6G RAN, which may result in different exchange rates between a 5G L2 scheduler and a 6G L2 scheduler. For example, an MRSS system with a cloud native RAN deployment for 6G and a classical deployment for 5G (e.g., in which CU / DU and RU are co-located) may result in a considerable delay between the 5G scheduler and the 6G scheduler. In this example, the exchange rate may be limited due to the non-co-located 5G and 6G RAN deployments.

[0095] Therefore, it may be desirable to take a potential delay in communication between 5G and 6G schedulers into account when implementing a dynamic sharing of resources.

[0096] Smart resource splitting between 5G and 6G RATs may enable more efficient MRSS. A resource split that reflects the traffic load per RAT (e.g., that avoids congestion of one RAT while the resources of the other RAT are not fully utilized) is therefore desirable.

[0097] Compared to a baseline of one RAT using the full spectrum, an MRSS deployment of two RATs sharing the spectrum may increase congestion (particularly on the uplink), especially when devices generating high data rates are not properly spread across the portion of the spectrum reserved to the two technologies (e.g., because a single RAT using the full spectrum may efficiently allocate resources using its scheduler, without the need for potentially inefficient coordination of resources between RATs).Contention based RACH procedure

[0098] Random access channel (RACH) procedures may allow terminal devices that do not have an RRC connection with a radio access network, or a node of the network, to establish an RRC connection. Initially, there may be no resources allocated to a terminal device to perform uplink communications (other than random access resources that are not allocated to any particular terminal device), and the terminal device may therefore rely on random access resources to establish a connection with the network, request resources, etc. Through the RACH procedure, a terminal device may perform an initial uplink communication. The RACH procedure may also provide the terminal device with uplink synchronization information, and a network node assigned ID.

[0099] In addition to initial access, RACH procedures may be used in beam recovery, handover procedures, etc.

[0100] In an example RACH procedure, a network node configures a set of RACH preambles and RACH occasions. These RACH preambles and RACH occasions may be indicated in system information (i.e., indicated in broadcast information accessible to terminal devices even without an RRC connection to the network node).

[0101] The RACH occasions comprise time / frequency resources on which a RACH preamble may be transmitted. The RACH preambles correspond to uncorrelated / orthogonal sequences, distinguishable by the network node even if received on the same time / frequency resource (at least under ideal radio conditions). The time / frequency / preamble combinations correspond to RACH resources configured in the system information. If each device attempting random-access at a particular time selects different RACH resources, then the network may determine the number of devices attempting random-access and identify the devices by the resources used.

[0102] In the RACH procedure, a terminal selects a preamble. This preamble may beselected randomly from RACH preambles, or randomly from a subset of RACH preambles (e.g., the subset may be based on a selected downlink beam / SSB index).

[0103] This random selection may result in the same preamble being randomly selected by multiple terminal devices performing the RACH procedure using the same RACH occasion. This may be referred to as RACH collision or a "contention". A RACH process that allows this type of "Contention" may be called a "Contention based" RACH Process.

[0104] To resolve this contention, the RACH procedure may take place as follows:

[0105] 1. A terminal device sends a RACH preamble to a network node;

[0106] 2. The network node sends "Msg2" to the terminal device, including a randomaccess radio network temporary identifier, RA-RNTI, a temporary cell radio network temporary identifier, T_C-RNTI, an uplink grant, and a timing advance, TA;

[0107] 3. The terminal device sends "Msg3" to the network node, carried by PUSCH with a cell radio network temporary identifier, C-RNTI; and

[0108] 4. The network node sends "Msg4" to the terminal device, carried by PDSCH, with a contention resolution message.

[0109] If two terminal devices send the same preamble on the same time / frequency resources, both terminal devices will receive the same T_C-RNTI and they will decode the same Msg2 (presuming that both receive Msg2 successfully).

[0110] Then, two msg3 will be sent by the two terminal devices, and the network node may decode one of these two messages and reply to one, treating msg3 from the other terminal device as interference. A hybrid automatic repeat request (HARQ) acknowledgement (ACK) is provided by the network node to the terminal device in step 4 and called "contention resolution" process.

[0111] Notably, it is possible that the network node is unable to detect the RACHmessages (preambles) from either terminal device, and thus the RACH attempts of both devices fail, and terminal devices may re-send the preambles to the network node.

[0112] Further, it is possible that the network node may be unable to decode either of the "msg3" received. Neither of the terminal devices will receive the HARQ ACK, and the RACH process re-starts.

[0113] In an example RACH procedure, a terminal device transmits a RACH preamble, using RACH resources.

[0114] Spectrum sharing and RACH resources

[0115] Dynamic spectrum sharing, e.g. as part of MRSS, between 5G and 6G RATs may be deployed for the reasons discussed above, particularly at lower frequencies (e.g., in FR1).

[0116] However, as summarized above, uplink congestion may be more severe in an MRSS deployment, as by design the uplink resources are split between two RATs.

[0117] Aspects of this disclosure address the efficient utilization of UL resources in a dynamic spectrum sharing context.

[0118] One option for addressing uplink congestion is to allocate more uplink resources (e.g., at the cost of downlink resources). For example, a different frame pattern in which more uplink slots are reserved could be considered. However, this is not always feasible as DL traffic growth may also increase, and is expected to increase significantly.

[0119] Another option is more efficient utilization of the same uplink resources (e.g., to offset some of the effects of spectrum sharing, by more efficiently allocating resources between RATs).Aspects of this disclosure address uplink resources for initial access.

[0120] One option for dynamic spectrum sharing of uplink resources for initial access is sharing RACH occasions (e.g., adapting the allocation of RACH occasions to different RATs based on traffic load).

[0121] Fig. 3 is a schematic diagram illustrating an example partition of RACH resources (RACH occasions in this example), designated generally by the reference numeral 300.

[0122] In the example partition, shared RACH occasions (ROs) are provided. These shared ROs may be dynamically allocated to the RATs. For example, the shared ROs may be partitioned between the RATs, and this partitioning may be adapted based on traffic load.

[0123] In this example, some ROs are dedicated for each RAT (e.g., some are dedicated 5G ROs, some are dedicated 6G ROs). This may set a minimum number of ROs that are allocated to each RAT at any time. In examples in which ROs are mapped to SSB indices (e.g., corresponding to downlink beams), providing dedicated ROs allocated to each RAT may assist with mapping SSB indices to RACH resources. In some examples the network node may rely on RO selection to indicate an SSB beam (e.g., to assist in Msg2 beamforming), and having sufficient ROs allocated to each RAT to maintain an RO to SSB mapping may therefore be useful.

[0124] Some ROs may be dedicated for each RAT, and in this example, at least one dedicated RO is allocated to each SSB index of each RAT. In other examples, dedicated ROs may be allocated to groups of SSB indices, etc.

[0125] Aspects of the present disclosure relate to extensions of the contention-based RACH procedure to facilitate efficient UL resource allocation and utilization. For example, the contention-based RACH procedure may be extended to facilitate informed decisions regarding the partition of shared ROs between the RATs.Fig. 4 is a flow diagram of a portion of an example RACH procedure, designated generally by reference numeral 400. The method may be carried out by a terminal device (such as a UE).

[0126] The method starts at step 410.

[0127] At step 412, the terminal device selects a RACH occasion and preamble. The terminal device may select the preamble randomly, or from a subset of preambles based on an SSB index to preamble mapping.

[0128] At step 414, the terminal device sends the preamble to the network node on the selected RO. The terminal device waits an amount of time (e.g., indicated in system information). In the case of four-step RACH, this may correspond to Msgl. In the case of two-step RACH, this may correspond to MsgA (and the terminal device may also send a PUSCH transmission).

[0129] At step 416, the terminal device either receives a response to the preamble (which may correspond to Msg2 in the four step RACH procedure or MsgB in the two step RACH procedure) from the network node (within a configured amount of time) or the terminal device does not receive the response.

[0130] If the terminal device does not receive the response (i.e., the configured amount of time expires), the method may proceed to step 418.

[0131] If the terminal device does receive the response, the method may proceed to step 422.

[0132] At step 418, the terminal device determines whether a number of attempts to transmit the preamble on the RO has exceeded a configured limit without receiving a response. If the number of attempts has not exceeded the limit, the method proceeds to step 420, at which the terminal device increases (increments) the transmit power used to transmit the preamble, and returns to step 414, at which the terminal device re-attempts the transmission with the increased transmitpower.

[0133] If the number of attempts to transmit the preamble on the RO has reached the limit, the method may proceed to step 424 and the RACH procedure may be deemed to have failed. In some examples the terminal device may return to step 412, and reselect an RO and preamble.

[0134] At step 422, if the terminal device receives a response to the preamble, the response of the terminal device may depend on the RACH procedure used. In the case of four-step RACH as described above, the terminal device may transmit Msg3 to the network node. In the case of two-step RACH, the response from the network node may correspond to MsgB of the two-step RACH procedure, and conclude the RACH procedure.

[0135] In method 400, the number of re-attempts is not indicated to the network node. The network node may therefore be unable to use the number of re-attempts in determining a number of collisions, to determine an efficient division of shared ROs between RATs.

[0136] Further, the following scenarios may occur in the example RACH procedures described above.

[0137] Assuming two terminal devices initiate a RACH procedure using the same RO, the following can occur:

[0138] 1. Terminal device 1 sends a preamble to the network node.

[0139] 2. Terminal device 2 sends the same preamble to the network node on the same RO.

[0140] 3. The network nodes sends terminal device 1 and 2 the same Msg2, including RA-RNTI, T_C-RNTI, UL grant, TA (as the network node has not identified two separate terminal devices)

[0141] 4. Terminal device 1 and 2 send Msg3 to the network node on PUSCH with C- RNTI5. The network node sends Msg4 to terminal device 1 on PDSCH, with the contention resolution message.

[0142] 6. The 4-step RACH succeeds for terminal device 1, however, terminal device 2 assumes that the RACH procedure has failed, and terminal device 2 initiates the RACH procedure from scratch.

[0143] In the above, the network node may be unaware that the RACH failure occurs for terminal device 2 due to collision.

[0144] A further scenario considers one terminal device:

[0145] 1. Terminal device 1 sends a preamble to the network node.

[0146] 2. Terminal device 1 does not receive Msg2 during the random access response (RAR) window.

[0147] 3. Terminal device 1 "re-attempts" by sending the same preamble to the network node, on the same RO. This may be repeated up to a network configured maximum number of attempts.

[0148] 4. The network node sends terminal device 1 Msg2, including RA-RNTI, T_C-RNTI, UL grant, TA

[0149] 5. Terminal device 1 sends Msg3 to the network node on PUSCH with C-RNTI 6. The network node sends Msg4 to terminal device 1 on PDSCH, with the contention resolution message.

[0150] In the above further scenario, the RACH procedure succeeds after a number of reattempts, but the network node may be unaware that multiple RACH attempts were required. The number of RACH attempts required can be influenced by radio conditions or collisions with other UEs.

[0151] When partitioning RACH resources, such as preambles and / or RACH occasions, between RATs, the following information may be useful in tracking collisions during the RACH procedure:

[0152] • A number of attempts or re-attempts during a RACH procedure.• A number of RACH failures, e.g., a number of times that the terminal device reaches the maximum allowed number of re-attempts without receiving a response (e.g., Msg2 in the case of four-step RACH and MsgB in the case of two-step RACH), and / or a number of times that the terminal device does not receive the contention resolution message (e.g., after sending a PUSCH during the RACH procedure).

[0153] • A terminal device transmit power of the latest RACH attempt. This may correspond to the most recent successful RACH attempt.

[0154] These performance metrics may allow effective tracking of the actual performance of RACH procedures of the RATs.

[0155] Further, the transmit power may be used to determine a reason for a RACH failure. For example, whether a previous RACH failure occurred due to radio conditions or collisions may be inferred from transmit power and measured uplink reference signal received power.

[0156] The network node may partition, or re-partition RACH resources based on the above information, to reduce the number of RACH collisions in a cell of one of the RATs.

[0157] For example, if the network node determines that a large number of collisions are occurring in a cell of a first RAT, and a smaller number of collisions are occurring in a cell of a second RAT, the network node the network node may re-partition RACH resources between the RATS.

[0158] In one example, the network node re-partitions RACH resources by re-partitioning RACH occasions. The re-partitioned RACH resources may be part of a subset of the total RACH resources across both cells (e.g., the RACH resources may comprise shared resources that may be re-partitioned dynamically, and dedicated resources that may be reserved for a respective RAT).

[0159] Fig. 5 is a signaling diagram of a method designated generally by referencenumeral 500.

[0160] In method 500, a terminal device 510 performs the four-step RACH procedure, attempting to connect to network node 520. Aspects of method 500 are applicable to other RACH procedures, such as two-step RACH.

[0161] At step 530, network node 520 indicates RACH resources to terminal device 510. This indication may be included in system information. This indication may be included in a broadcast message.

[0162] At step 532, network node 520 sends RACH failure reporting configuration information to terminal device 510. This configuration information indicates to the terminal device that it is to report events of the RACH procedure, or information associated with these events. For example, the RACH failure reporting configuration may indicate that the terminal device is to indicate (e.g., in the report) a number of attempts or re-attempts during a RACH procedure (e.g., the most recent procedure), and / or a number of attempts or reattempts across all RACH procedures (e.g., including failed RACH procedures and successful RACH procedures), during a defined time period. The time period may be defined in terms of events (e.g., between receipt of the configuration information and between transmission of the report), or in terms of a time (e.g., a number of subframes), or both (e.g., a number of subframes preceding or following an event). The RACH failure reporting configuration information may indicate that the terminal device is to indicate a number of RACH failures (e.g., failures to receive a random access response within a random access response window within the allowed number of re-attempts, and / or failures to receive a contention resolution message). The RACH failure reporting configuration information may indicate or define a time period, related to RACH failure reporting (i.e., the reporting configuration may indicate that the terminal device is to indicate the number of RACH failures within this time period), which may be the same as or different to the time period for reattempt reporting. The RACH failure reporting configuration information may indicate that the terminal device is to indicate in a report a transmission power used to transmit a RACH preamble. For example, the RACHfailure reporting configuration may indicate that the terminal device is to indicate the transmission power of the latest preamble transmission (i.e., which results in success of the RACH procedure).

[0163] At step 534, in this example, a time window (e.g., one or more of the time periods described above) for terminal device 510 to collect RACH failure information to report may begin. For example, the RACH failure reporting configuration information may indicate that RACH failures, RACH attempts or re-attempts, and / or a transmission power of the most recent preamble transmission should be recorded from this point, for later transmission to the network in a report.

[0164] At step 536, terminal device 510 sends a RACH preamble to the network using a RACH occasion (e.g., using the frequency / time resources of RACH occasion). The preamble, RO, and / or combination of preamble and RO may be selected randomly, or randomly from a subset of preamble and RO combinations.

[0165] At step 538, a time window for receiving a response to the RACH preamble expires without the terminal device 510 successfully receiving the response from the network.

[0166] At step 540, terminal device 510 stores information associated with the attempt. For example, device 510 may increment a re-attempt counter, and / or store information related to the attempt, such as an indication of the time, preamble used, RO used, etc.

[0167] At step 542, terminal device 510 re-attempts transmission of the preamble (using the same RO), with incremented transmission power. This preamble is successfully received and decoded by network node 520.

[0168] At step 544, network node 520 sends a response to terminal device 510, which receives the response. For example, this response may correspond to Msg2 of the four step RACH procedure.At step 546, terminal device 510 sends a RACH failure report to network node 520, in accordance with the RACH failure reporting configuration, including information indicative of the number of reattempts and / or the most recently used preamble transmission power. This report may be sent during the RACH procedure (e.g., in the first PUSCH of the RACH procedure, before receipt of Ms4 of the four step RACH procedure, or before receipt of MsgB of the two step RACH procedure). Successful reception of the report may correspond to success of the RACH procedure (e.g., because this may correspond to the PUSCH in which the report is sent being successfully decoded). If the network node does not successfully receive the report, this may correspond to an unsuccessful RACH procedure, and a subsequent report may include information indicative of this RACH failure. In accordance with the reporting configuration, the RACH failure report may include RACH failure information related to events, such as attempts or re-attempts, the transmission power of the most recent attempt or re-attempt, and RACH failures, occurring between the start of the time window and transmission of the report (e.g., between receipt of the reporting configuration and transmission of the report, or in period of time preceding transmission of the report). Method 500 includes a re-attempt, but example methods may additionally or alternatively include multiple re-attempts, a RACH failure and / or RACH failures, and the report may include information reflecting this.

[0169] At step 548, the time window covered by the RACH failure report at step 546 ends with the transmission of the report. In the event of a failure to receive the contention resolution message, the time window may be extended to cover the transmission of a further report. The contention resolution message may be received in a PDSCH.

[0170] At step 550, terminal device 510 receives a contention resolution message from network node 520. The RACH procedure may be considered successful at this point, with the first PUSCH and PDSCH transmissions having been successfully received (e.g., msg3 may be received at the network node and msg4 may be received at the terminal device respectively).At step 552, based on at least in part on the RACH failure report (e.g., based on a plurality of RACH failure reports), the network determines to repartition RACH resources, such as RACH occasions. For example, the network may determine, based at least in part on the RACH failure reports, the frequency of collisions for a first RAT, and a frequency of collisions for a second RAT, and repartition the RACH resources between the RATs (e.g., to increase utilization of underutilized RACH resources, and / or to reduce collisions on one of the RATs).

[0171] Fig. 6 is a flow diagram of a method designated generally by reference numeral 600.

[0172] Method 600 may be carried out at a terminal device, such as a UE, communicating with a network node. For example, the terminal device may be a 5G NR capable device communicating with a gNB, or a 6G RAT capable device communicating with a 6G base station. The terminal device may be in communication with a network node participating in MRSS. Method 600 may be performed as part of the two-step or four-step RACH procedure.

[0173] At step 610, a terminal device receives from a network node of a mobile communications network a configuration indicating RACH procedure information for reporting by the terminal device.

[0174] At step 612, the terminal device performs at least one RACH procedure.

[0175] In some example embodiments, performing the at least one RACH procedure comprises selecting a RACH preamble and RACH occasion, and performing at least one RACH attempt, wherein respective RACH attempts of the at least one RACH attempt comprise transmitting the selected preamble on the selected RACH occasion.

[0176] At step 614, the terminal device sends to the network node information associated with the at least one RACH procedure based at least in part on the configuration.By receiving the reporting configuration and sending RACH failure information based on the reporting configuration, the terminal device may report RACH failure information to a network node based on the network node's needs. For example, a network node using MRSS may have a greater requirement for RACH failure information, so that it may partition RACH resources between RATs efficiently, while a network node that does not use MRSS may have a lesser requirement for RACH failure information, and reporting extensive RACH failure information may result in needless signaling overhead. Basing the report on the configuration allows the report to be sent responsive to the network node indicating a need for the information of the report and allows the content of the report to be based on the needs of the network node.

[0177] In some example embodiments, sending information comprises, based at least in part on the configuration, sending information indicative of at least one of: a number of RACH attempts performed by the terminal device; a number of RACH procedures performed by the terminal device that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; and a transmit power used by the terminal device to transmit the selected preamble during a RACH attempt. In some examples, a RACH procedure that concludes by reaching the configured number of RACH attempts without receiving a response to the preamble transmission can be considered to have concluded in RACH failure. In some examples, sending information comprises indicating a number of RACH failures of this kind, or a number of RACH failures generally.

[0178] In some examples, in the context of the two-step RACH procedure, a RACH failure may generally be considered to occur when a RACH procedure concludes without the terminal device receiving MsgB. For example, the terminal device may infer RACH failure if it fails to receive a response to the preamble within a configured number of re-attempts.In some examples, in the context of the four-step RACH procedure, a RACH failure may generally be considered to occur when a RACH procedure concludes without the terminal device receiving Msg4. For example, the terminal device may infer RACH failure if it fails to receive the response to the preamble within a configured number of re-attempts (e.g., due to radio conditions), or RACH failure may be inferred if the terminal device fails to receive Msg4 even after Msg2 is successfully received (e.g., due to collision or radio conditions).

[0179] In some examples, a RACH failure may more generally be considered to occur when the RACH procedure concludes (e.g., based at least in part on the terminal device not having received a response to an uplink communication) without the terminal device successfully decoding a PDSCH communication.

[0180] In some examples, the configuration is indicative of a window; and sending information comprises sending information associated with at least one event of the at least one RACH procedure based at least in part on the event occurring within the window. For example the configuration may indicate that the window begins with receipt of the configuration and concludes with sending the information / a successful RACH procedure, or that the window concludes with sending the information / a successful RACH procedure and begins a configured period / number of subframes before the sending of the information (e.g., information may be stored before the time period covered by the window is known, the window may be determined when the time of transmission of the information is known, and the information sent may be based on stored information associated with the window).

[0181] In some example embodiments, sending the information comprises sending, based at least in part on the configuration, information indicative of a number of RACH attempts performed by the terminal device within the window.

[0182] In some example embodiments, sending the information comprises sending, based at least in part on the configuration, information indicative of a number of RACH procedures performed by the terminal device within the window thatconclude with a RACH failure. For example, the information may be indicative of a number of RACH procedures performed within the window and that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

[0183] In some example embodiments, sending the information comprises sending, based at least in part on the configuration, information indicative of a RACH occasion and / or RACH preamble used by the terminal device in a RACH procedure performed by the terminal device within the window that concludes with a RACH failure.

[0184] In some example embodiments, sending the information comprises sending, based at least in part on the configuration, information indicative of an SSB index mapped to at least one of a RACH preamble and a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window that concludes with a RACH failure. This information may for example be useful in determining whether RACH resources associated particular downlink beams / sets of downlink beams correspond to higher rates of collision, which may indicate that some SSBs / downlink beams are underused compared to other SSBs / downlink beams (e.g., because terminal devices are not evenly distributed amongst the beams). This may allow the re-partitioning to account for per-beam RACH performance in addition to per-RAT RACH performance. For example, in examples in which ROs are mapped to SSB indices, SSBs indices with a relatively high rate of collisions could be prioritized in the mapping (e.g., so that the SSB indices with a relatively high rate of collisions are mapped to a larger number of ROs, to reduce the chance of collision).

[0185] In some example embodiments, sending the information comprises sending, based at least in part on the configuration, information indicative of a transmit power used by the terminal device to transmit a RACH preamble in the most recent RACH attempt within the window. In some examples, transmit power informationmay indicate whether a RACH failure results from radio conditions (such as noise, interference, attenuation, etc.) or collision with another terminal device using the same RACH resources.

[0186] In some example embodiments, receiving the configuration comprises receiving the configuration via at least one of: a system information broadcast by the network node; RRC signaling; paging; and a PDCCH instruction to perform a RACH procedure.

[0187] In some example embodiments, sending the information comprises sending the information as part of the second uplink message of a four-step RACH procedure.

[0188] In some example embodiments, sending the information comprises sending the information as part of the first uplink message of a two-step RACH procedure.

[0189] Fig. 7 is a flow diagram of a method designated generally by reference numeral 700.

[0190] Method 700 may be carried out at a network node, such as a base station. The network node may be capable of communicating with terminal devices, such as UEs. The network node may part of, or may comprise, a gNB and or a 6G RAT base station. The network node may perform MRSS. Method 700 may be performed as part of the two-step or four-step RACH procedure.

[0191] At step 710, the network node sends, to a terminal device, a configuration indicating RACH procedure information for reporting by the terminal device.

[0192] At step 712, the network node receives, from the terminal device, information associated with at least one RACH procedure performed by the terminal device.

[0193] In some examples the at least one RACH procedure comprises: selecting (by the terminal device) a RACH preamble and RACH occasion, and performing at least one RACH attempt, wherein respective RACH attempts of the at least one RACHattempt comprise transmitting the selected preamble on the selected RACH occasion.

[0194] In some examples, receiving the information comprises receiving information indicative of at least one of: a number of RACH attempts performed by the terminal device; a number of RACH procedures performed by the terminal device that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; and a transmit power used by the terminal device to transmit the selected preamble during a RACH attempt.

[0195] At step 714, in some examples, the network node determines, based at least in part on the information of step 712, that a RACH collision or a plurality of RACH collisions has occurred. For example, in some examples the network node may receive an indication that the transmit power of the most recent successful RACH attempt is relatively small (indicating that the radio conditions are likely not responsible for a RACH failure), and that at least one RACH failure has occurred, and infer that the RACH failure or RACH failures are the result of collisions.

[0196] At step 716, in some examples, the network node re-partitions RACH resources (e.g., ROs and / or preambles) between RATs. This re-partitioning may be based at least in part on the determination made at step 714. The re-partitioned RACH resources may be shared resources (e.g., non-shared, dedicated resources for one or both RATs may be unaffected by the re-partitioning). The re-partitioning may comprise changing system information of cells of different RATs to indicate a larger or smaller set of RACH resources available for RACH procedures. For example, the re-partitioning may increase the RACH resources available for a RAT with a large number of collisions and decrease the RACH resources available for a RAT with a small number of collisions.

[0197] In some examples, the steps of network node method 700 may have features corresponding to those discussed in connection with terminal device method600.

[0198] For completeness, FIG. 8 is a schematic diagram of components of one or more of the example embodiments described previously, which hereafter are referred to generically as a processing system 1800. The processing system 1800 may, for example, be comprised by the device referred to in the claims below.

[0199] The processing system 1800 may have a processor 1802, a memory 1804 closely coupled to the processor and comprised of a Random Access Memory (RAM) 1814 and a Read Only Memory (ROM) 1812, and, optionally, a user input 1810 and a display 1818. The processing system 1800 may comprise one or more network / apparatus interfaces 1808 for connection to a network / apparatus, e.g., a modem which may be wired or wireless. The network / apparatus interface 1808 may also operate as a connection to other apparatus such as device / apparatus which is not network side apparatus. Thus, direct connection between devices / apparatus without network participation is possible.

[0200] The processor 1802 is connected to each of the other components in order to control operation thereof.

[0201] The memory 1804 may comprise a non-volatile memory, such as a hard disk drive (HDD) or a solid-state drive (SSD). The ROM 1812 of the memory 1804 stores, amongst other things, an operating system 1815 and may store software applications 1816. The RAM 1814 of the memory 1804 is used by the processor 1802 for the temporary storage of data. The operating system 1815 may contain code which, when executed by the processor implements aspects of the methods 400, 500, 600, and 700 described above. Note that in the case of small device / apparatus the memory can be most suitable for small size usage i.e., not always a hard disk drive (HDD) or a solid state drive (SSD) is used.

[0202] The processor 1802 may take any suitable form. For instance, it may be a microcontroller, a plurality of microcontrollers, a processor, or a plurality of processors.The processing system 1800 may be a standalone computer, a server, a console, or a network thereof. The processing system 1800 and needed structural parts may be all inside device / apparatus such as loT device / apparatus i.e., embedded to very small size.

[0203] In some example embodiments, the processing system 1800 may also be associated with external software applications. These may be applications stored on a remote server device / apparatus and may run partly or exclusively on the remote server device / apparatus. These applications may be termed cloud-hosted applications. The processing system 1800 may be in communication with the remote server device / apparatus in order to utilize the software application stored there.

[0204] FIG. 9 shows a tangible media, in the form of a removable memory unit 1910, storing computer-readable code which when run by a computer may perform methods according to example embodiments described above. The removable memory unit 1910 may be a memory stick, e.g., a Universal Serial Bus (USB) memory stick, having internal memory 1930 storing the computer-readable code. The internal memory 1930 may be accessed by a computer system via a connector 1920. Of course, other forms of tangible storage media may be used, as will be readily apparent to those of ordinary skilled in the art. Tangible media can be any device / apparatus capable of storing data / information which data / information can be exchanged between devices / apparatus / network.

[0205] Embodiments of the present invention may be implemented in software, hardware, application logic or a combination of software, hardware and application logic. The software, application logic and / or hardware may reside on memory, or any computer media. In an example embodiment, the application logic, software or an instruction set is maintained on any one of various conventional computer-readable media. In the context of this document, a "memory" or "computer-readable medium" may be any non-transitory media or means that can contain, store, communicate, propagate or transport theinstructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0206] Reference to, where relevant, "computer-readable medium", "computer program product", "tangibly embodied computer program" etc., or a "processor" or "processing circuitry" etc. should be understood to encompass not only computers having differing architectures such as single / multi-processor architectures and sequencers / parallel architectures, but also specialised circuits such as field programmable gate arrays (FPGA), application specific integrated circuits (ASIC), signal processing devices / apparatus and other devices / apparatus. References to computer program, instructions, code etc. should be understood to express software for a programmable processor firmware such as the programmable content of a hardware device / apparatus as instructions for a processor or configured or configuration settings for a fixed function device / apparatus, gate array, programmable logic device / apparatus, etc.

[0207] If desired, the different functions discussed herein may be performed in a different order and / or concurrently with each other. Furthermore, if desired, one or more of the above-described functions may be optional or may be combined. Similarly, it will also be appreciated that the flow and signalling diagrams of Figures 4 - 7 are examples only and that various operations depicted therein may be omitted, reordered and / or combined.

[0208] It will be appreciated that the above-described example embodiments are purely illustrative and are not limiting on the scope of the invention. Other variations and modifications will be apparent to persons skilled in the art upon reading the present specification.

[0209] Moreover, the disclosure of the present application should be understood to include any novel features or any novel combination of features either explicitly or implicitly disclosed herein or any generalization thereof and during the prosecution of the present application or of any application derived therefrom,new claims may be formulated to cover any such features and / or combination of such features.

[0210] Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described example embodiments and / or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims.

[0211] It is also noted herein that while the above describes various examples, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims.

Claims

Claims1. A terminal device comprising:means for receiving from a network node of a mobile communications network a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device;means for performing at least one RACH procedure; andmeans for sending to the network node information associated with the at least one RACH procedure based at least in part on the configuration.

2. The terminal device of claim 1, wherein the at least one RACH procedure comprises:selecting a RACH preamble and RACH occasion; andperforming at least one RACH attempt, wherein respective RACH attempts of the at least one RACH attempt comprise transmitting the selected preamble on the selected RACH occasion.

3. The terminal device of claim 2, wherein the means for sending information is configured to send, based at least in part on the configuration, information indicative of at least one of:a number of RACH attempts performed by the terminal device;a number of RACH procedures performed by the terminal device that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; anda transmit power used by the terminal device to transmit the selected preamble during a RACH attempt.

4. The terminal device of claim 2, wherein:the configuration is indicative of a window; andthe means for sending information is configured to send information associated with at least one event of the at least one RACH procedure based atleast in part on the event occurring within the window.

5. The terminal device of claim 4, wherein the means for sending information is configured to send, based at least in part on the configuration, information indicative of a number of RACH attempts performed by the terminal device within the window indicated by the configuration.

6. The terminal device of claim 4 or claim 5, wherein the means for sending information is configured to send, based at least in part on the configuration, information indicative of a number of RACH procedures performed by the terminal device within the window that comprise:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

7. The terminal device of any of claims 4 to 6, wherein the means for sending information is configured to send, based at least in part on the configuration, information indicative of a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

8. The terminal device of any of claims 4 to 7, wherein the means for sending information is configured to send, based at least in part on the configuration, information indicative of a RACH preamble used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

9. The terminal device of any of claims 4 to 8, wherein the means for sending information is configured to send, based at least in part on the configuration, information indicative of an SSB index mapped to at least one of a RACH preamble and a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

10. The terminal device of any of claims 4 to 9, wherein the means for sending information is configured to send, based at least in part on the configuration, information indicative of a transmit power used by the terminal device to transmit a RACH preamble in the most recent RACH attempt within the window.

11. The terminal device of any preceding claim, wherein the means for receiving the configuration is configured to receive the configuration via a system information broadcast by the network node.

12. The terminal device of any preceding claim, wherein the means for receiving the configuration is configured to receive the configuration via at least one of:RRC signaling;paging; anda physical downlink control channel, PDCCH, instruction to perform a RACH procedure.

13. The terminal device of any preceding claim, wherein the means for sending information is configured to send the information as part of the second uplink message of a four-step RACH procedure.

14. The terminal device of any of claims 1 - 12, wherein the means for sending information is configured to send the information as part of the first uplink message of a two-step RACH procedure.

15. A network node comprising:means for sending, to a terminal device, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; andmeans for receiving from the terminal device information associated with at least one RACH procedure performed by the terminal device.

16. The network node claim 15, wherein the at least one RACH procedure comprises:selecting a RACH preamble and RACH occasion, andperforming at least one RACH attempt, wherein respective RACH attempts of the at least one RACH attempt comprise transmitting the selected preamble on the selected RACH occasion.

17. The network node of claim 16, wherein the means for receiving information is configured to receive information indicative of at least one of: a number of RACH attempts performed by the terminal device;a number of RACH procedures performed by the terminal device that comprise: performing a number of RACH attempts; and concluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt; anda transmit power used by the terminal device to transmit the selected preamble during a RACH attempt.

18. The network node of claim 16, wherein:the configuration is indicative of a window; andthe means for receiving information is configured to receive information associated with at least one event of the at least one RACH procedure, the event having occurred within the window.

19. The terminal device of claim 16, wherein the means for receiving information is configured to receive information indicative of a number of RACH attempts performed by the terminal device within the window indicated by the configuration.

20. The network node of claim 19, wherein the means for receiving information is configured to receive information indicative of a number of RACH procedures performed by the terminal device within the window that comprise:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

21. The network node of claim 19 or claim 20, wherein the means for receiving information is configured to receive information indicative of a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

22. The network node of any of claims 19 - 21, wherein the means for receiving information is configured to receive information indicative of a RACHpreamble used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

23. The network node of any of claims 19 - 22, wherein the means for receiving information is configured to receive information indicative of an SSB index mapped to at least one of a RACH preamble and a RACH occasion used by the terminal device in a RACH procedure performed by the terminal device within the window and that comprises:performing a number of RACH attempts; andconcluding the RACH procedure based on the number of RACH attempts performed reaching a configured number without the terminal device receiving a response to the preamble transmission of a RACH attempt.

24. The network node of any of claims 19 - 23, wherein the means for receiving information is configured to receive information indicative of a transmit power used by the terminal device to transmit a RACH preamble in the most recent RACH attempt within the window.

25. The network node of any of claims 15 - 24, wherein the means for sending the configuration is configured to send the configuration via a system information broadcast by the network node.

26. The network node of any of claims 15 - 24, wherein the means for sending the configuration is configured to send the configuration via at least one of:RRC signaling;paging; anda physical downlink control channel, PDCCH, instruction to perform a RACH procedure.

27. The network node of any of claims 15 - 26, wherein:the means for receiving the information is configured to receive the information as part of the second uplink message of a four-step RACH procedure.

28. The terminal device of any of claims 15 - 27, wherein:the means for receiving the information is configured to receive the information as part of the first uplink message of a two-step RACH procedure.

29. A method comprising:receiving, at a terminal device from a network node of a mobile communications network, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device;performing, by the terminal device, at least one RACH procedure; and sending, from the terminal device to the network node, information associated with the at least one RACH procedure based at least in part on the configuration.

30. A method comprising:sending, from a network node to a terminal device, a configuration indicating random access channel, RACH, procedure information for reporting by the terminal device; andreceiving, at the network node from the terminal device, information associated with at least one RACH procedure performed by the terminal device.

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