METHOD AND UE FOR ACCESSING A SLICE-SPECIFIC RACH RESOURCE POOL - Patent application

Abstract

A method and system are provided for accessing a network slice-specific random access channel resource pool at a user equipment. A wireless communication system includes a base station (gNB), BS, and a user equipment (UE), wherein the user equipment is in a connected mode having an inactive state and initiates a random access procedure for resuming a radio resource control (RRC) connection. Accordingly, at least one slice identifier is provided from a non-access stratum (NAS) layer to an access stratum (AS), and at least one network slice is determined to be used for the radio resource control (RRC) connection based on the provided at least one slice identifier.

Description

[Technical Field]

[0001] The present disclosure relates generally to mobile communication networks, such as 5G communication networks, and more particularly to random access channel (RACH) configuration selection. [Background technology]

[0002] The fifth-generation technology standard (5G) for broadband cellular networks targets diverse use cases and industries. A more distributed core with a combination of diverse Radio Access Network (RAN) deployments is generally seen as a framework for greater flexibility, customization, and service-centric management in a viable 5G system. From a network traffic management perspective, 5G also enables the coordination of different services and provides the provisions for enhancing mobile network performance.

[0003] The main 5G data-driven use cases relate to: Enhanced Mobile Broadband (eMBB) requires high data rates over a wide radio coverage area when users communicate wirelessly with base stations in normal radio operation and with good radio coverage. However, other use cases and traffic types exist with different needs (URLLC, V2X, IoT). A standardized method differentiates various traffic characteristics to facilitate dedicated treatment and ultimately the desired goals. 3GPP Technical Specification 23.501 defines a 5G Quality of Service (QoS) Identifier (5QI) for services expected to be frequently used in 5G, enabling service-optimized signaling per service and reflecting 5G QoS characteristics and profiles.

[0004] To enable differentiated treatment according to each customer's requirements, 5G also supports the concept of network slicing. With network slicing, a mobile network operator (MNO) can consider customers as belonging to different tenant types, with different service requirements governing the slice types each tenant can use based on their service level agreement (SLA) and subscription. Support for network slicing relies on the principle that traffic for different slices is handled by different protocol data unit (PDU) sessions. The network can realize different network slices through scheduling and also by providing different configurations. Summary of the Invention

[0005] The access stratum (AS) layer of the UE performs the RACH random access procedure, and the NAS layer handles information about the network slice. Therefore, the NAS layer in the UE provides information about the requested network slice to the AS layer. Currently, TS 24.501 supports providing a slice identifier from the NAS to the AS layer when the UE is in idle mode and sends an initial NAS message (see, for example, TS 24.501, V16.8.0, clause 4.6.2.3). However, in the future, the UE may be enabled to select between multiple available RACH access procedures based on the requested network slice. Therefore, it is necessary to define a procedure for a UE that is connected but in an inactive mode.

[0006] In this regard, methods, systems, and computer programs are presented for accessing slice-specific RACH resource pools.

[0007] According to a first aspect, a method for accessing a network slice-specific random access channel (RACH) resource pool in a user equipment (UE) is presented. The UE is in a connected mode having an inactive state and initiates a random access (RA) procedure for resumption of a radio resource control (RRC) connection. The method includes providing at least one slice identifier from a non-access stratum (NAS) layer to an access stratum (AS) layer; and determining, by the AS layer, at least one network slice to use for the RRC connection based on the provided at least one slice identifier.

[0008] In an embodiment, providing the at least one slice identifier is performed in response to an RA procedure initiated by one or more protocol data units, PDUs, at least one uplink user data packet of the session, and the at least one slice identifier is associated with the PDU session.

[0009] In a further embodiment, providing the at least one slice identifier is performed in response to the RA procedure being a UE-initiated 5G Mobility Management, 5GMM, procedure, and the 5GMM procedure being invoked by a UE-initiated NAS transport procedure for delivering one or more 5G Session Management, 5GSM, messages, and the at least one slice identifier is associated with the 5GSM message.

[0010] In an embodiment, at least one slice identifier corresponds to a single network slice selection assistance information (S-NSSAI) comprising a standardized slice / service type (SST). Further, the S-NSSAI may comprise an operator-defined access category corresponding to the network slice.

[0011] In an embodiment, the method further includes applying RACH configuration parameters corresponding to the at least one determined network slice to RA procedure selection and preamble transmission.

[0012] According to a second aspect, there is provided a user equipment (UE) for accessing a slice-specific random access channel (RACH) resource pool. The UE is thus in a connected mode having an inactive state and initiates a random access (RA) procedure for resumption of a radio resource control (RRC) connection. The UE is configured to provide at least one slice identifier from a non-access stratum (NAS) layer to an access stratum (AS) layer, and to determine at least one network slice to use for the RRC connection based on the at least one slice identifier provided by the AS layer.

[0013] According to a third aspect, there is provided a base station, BS, for resumption of a radio resource control, RRC, connection with a user equipment, UE, according to the present invention, wherein the BS is configured to: configure a network slice-specific random access channel, RACH, configuration per network slice or network slice group, the RACH configuration being associated with a slice identifier; transmit the RACH configuration to the UE; and receive a preamble transmission from the UE with RACH configuration parameters corresponding to the transmitted RACH configuration.

[0014] According to a fourth aspect, there is provided a wireless communication system comprising a base station (BS) according to the present invention and a user equipment (UE), the system being configured to: configure, at the BS, a network slice-specific random access channel (RACH) configuration for each network slice or network slice group, where the RACH configuration is associated with a slice identifier; transmit the RACH configuration from the BS to the UE; provide at least one slice identifier from a non-access stratum (NAS) layer of the UE to an access stratum (AS) layer of the UE; determine a network slice or a group of network slices to use for an RRC connection based on the at least one slice identifier provided by the AS layer of the UE; and transmit, from the UE to the BS, a preamble comprising RACH configuration parameters corresponding to the determined RACH configuration.

[0015] According to a fifth aspect, there is provided a computer program comprising computer program code which, when executed by a computer, causes at least one computer to perform a method as set out herein.

[0016] According to a sixth aspect, there is provided a computer program product comprising program instructions stored on a computer readable medium for carrying out the methods described herein.

[0017] A better understanding of the subject matter described herein may be obtained from the following detailed description of various embodiments when considered in conjunction with the following drawings. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 illustrates a simplified wireless communication system according to some embodiments. [Figure 2] FIG. 1 illustrates a base station (BS) in communication with a user equipment (UE), according to some embodiments. [Figure 3]FIG. 2 illustrates a simplified block diagram of a UE, according to some embodiments. [Figure 4] FIG. 10 is a visualization of the basic procedure for accessing a network slice-specific random access channel (RACH) resource pool at a user equipment (UE). [Figure 5] FIG. 1 illustrates a procedure for using a group of network slices provided by a NAS for communication between a base station and a UE, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0019] 1 illustrates a simplified wireless communication system 100 according to some embodiments. It is noted that the system of FIG. 1 is merely one example of a possible system, and that the features of the subject matter described herein may be implemented in any of a variety of systems.

[0020] As shown, the wireless communication system 100 includes a base station 110-1 that communicates with one or more user devices 120 over a transmission medium. In FIG. 1 , only one base station 110-1 and three user devices 120-1, 120-2, and 120-3 are shown, without limitation. Each of the user devices 120-1, 120-2, and 120-3 may be referred to herein as a “user equipment” (UE). Accordingly, the user devices 120 are referred to as UEs or UE devices.

[0021] As used herein, the term "user equipment" may refer to any of various types of computer system devices that are mobile or portable and communicate wirelessly. Examples of UE include mobile phones or smartphones, portable gaming devices, laptops, wearable devices (e.g., smart watches, smart glasses), personal digital assistants (PDAs), portable Internet devices, music players, data storage devices, or other mobile devices. In general, the term "UE" or "UE device" may be broadly defined to encompass any electronic, computing, and / or telecommunications device (or combination of devices) that is easily transported by a user and has the capability for wireless communication.

[0022] Base station (BS) 110-1 may be a base transceiver station (BTS) or cell site (“cellular base station”) and may include hardware that enables wireless communication with UE 120.

[0023] As used herein, the term "base station" has the full scope of its ordinary meaning and includes at least a wireless communication station installed at a fixed location and used to communicate as part of a wireless telephone system and radio system.

[0024] The communication area (or coverage area) of the base station 110 may be referred to as a "cell." The base station 110 and the UE 120 may be configured to communicate over a transmission medium using any of a variety of radio access technologies (RATs), also referred to as wireless communication technologies or telecommunications standards, such as GSM, UMTS (e.g., associated with a WCDMA or TD-SCDMA air interface), LTE, LTE Advanced (LTE-A), 5G New Radio (5G NR), HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), etc. If the base station 110-1 is implemented in the context of LTE, it may alternatively be referred to as an "eNodeB" or "eNB." If the base station 110-1 is implemented in the context of 5G NR, it may alternatively be referred to as a "gNodeB" or "gNB."

[0025] As shown, the base station 110-1 may also be equipped to communicate with a network 130 (e.g., a cellular service provider's core network, a telecommunications network such as the Public Switched Telephone Network (PSTN), and / or the Internet, among other possibilities). Thus, the base station 110-1 may facilitate communications between user equipment 120 and / or between user equipment 120 and the network 130. In particular, the cellular base station 110-1 may provide various telecommunications capabilities to the UEs 120, such as voice, SMS, and / or data services.

[0026] Base station 110-1 and other similar base stations (such as base stations 110-2 and 110-3) operating according to the same or different cellular communication standards may thus be provided as a network of cells, which may provide overlapping or near-overlapping services to UEs 120 and similar devices over a geographic region via one or more cellular communication standards.

[0027] Thus, base station 110-1 may function as a “serving cell” for UE 120 as shown in FIG. 1, and each UE 120 may also have the capability to receive signals from (and possibly within communication range of) one or more other cells (which may be provided by base station 110 and / or any other base stations), which may also be referred to as “neighboring cells.” Such cells may also have the capability to facilitate communication between user equipment 120 and / or between user equipment 120 and network 130. Such cells may include “macro” cells, “micro” cells, “pico” cells, and / or cells providing any of various other granularities of service area size. For example, base stations 110-1 and 110-2 shown in FIG. 1 may be macro cells, while base station 110-3 may be a micro cell. Other configurations are possible.

[0028] In some embodiments, base station 110-1 may be a next-generation base station, e.g., a 5G New Radio (5G NR) base station, or "gNB." In some embodiments, a gNB may be connected to a legacy Evolved Packet Core (EPC) network and / or an NR Core (NRC) network. In addition, a gNB cell may include one or more Transition and Reception Points (TRPs). In addition, a UE capable of operating in accordance with 5G NR may be connected to one or more TRPs within one or more gNBs.

[0029] The UE 120 may be capable of communicating using multiple wireless communication standards. For example, the UE 120 may be configured to communicate using at least one cellular communication protocol (e.g., GSM, UMTS (e.g., associated with a WCDMA or TD-SCDMA air interface), LTE, LTE-A, 5G NR, HSPA, 3GPP2 CDMA2000 (e.g., 1xRTT, 1xEV-DO, HRPD, eHRPD), etc.), as well as wireless networking (e.g., Wi-Fi) and / or peer-to-peer wireless communication protocols (e.g., Bluetooth, Wi-Fi peer-to-peer, etc.). The UE 120 may also, or instead, be configured to communicate using one or more global navigation satellite systems (GNSS, e.g., GPS or GLONASS), one or more mobile television broadcast standards (e.g., ATSC-M / H or DVB-H), and / or any other wireless communication protocols as desired. Other combinations of wireless communication standards (including more than two wireless communication standards) are also possible.

[0030] 2 illustrates user equipment 120 (e.g., one of devices 120-1, 120-2, and 120-3) communicating with base station 110, according to some embodiments. UE 120 may be a device with cellular communication capabilities, such as a mobile phone, a handheld terminal, a computer or tablet, or virtually any type of wireless device.

[0031] The UE 120 may include a processor configured to execute program instructions stored in memory. The UE 120 may perform any of the method embodiments described herein by executing such stored instructions. Alternatively, or in addition, the UE 120 may include a programmable hardware element, such as a field programmable gate array (FPGA), configured to perform any of the method embodiments described herein, or any portion of any of the method embodiments described herein.

[0032] The UE 120 may include one or more antennas for communication using one or more wireless communication protocols or technologies. In some embodiments, the UE 120 may be configured to communicate using, for example, CDMA2000 (1xRTT / 1xEV-DO / HRPD / eHRPD), or LTE using a single shared radio, and / or GSM or LTE using a single shared radio. To perform wireless communication, the shared radio may be coupled to a single antenna or may be coupled to multiple antennas (e.g., for MIMO). In general, the radio may include any combination of baseband processors, analog RF signal processing circuits (e.g., including filters, mixers, oscillators, amplifiers, etc.), or digital processing circuits (e.g., for digital modulation and other digital processing). Similarly, the radio may implement one or more receive and transmit chains using the hardware described above. For example, the UE 120 may share one or more portions of the receive and / or transmit chains among multiple wireless communication technologies, such as those discussed above.

[0033] In some embodiments, the UE 120 may include a separate transmit and / or receive chain (e.g., including separate antennas and other radio components) for each wireless communication protocol configured to communicate with it. As a further possibility, the UE 120 may include one or more radios shared among multiple wireless communication protocols and one or more radios used exclusively by a single wireless communication protocol. For example, the UE 120 may include a shared radio for communication using either LTE or 5G NR (or LTE or 1xRTT, or LTE or GSM), and separate radios for communication using each of Wi-Fi and Bluetooth. Other configurations are possible.

[0034] 3 shows a simplified block diagram of a UE 120 according to some embodiments. It is noted that the block diagram of the UE 120 in FIG. 3 is merely one example of a possible user equipment. According to embodiments, the UE 120 may be, among other devices, a user equipment, a mobile device or station, a wireless device or station, a desktop computer or computing device, a mobile computing device (e.g., a laptop, notebook, or portable computing device), a tablet, and / or a combination of devices.

[0035] As shown, UE 120 may include a set of components configured to perform core functions. For example, this set of components may be implemented as a system-on-chip (SOC), which may include portions for various purposes. Alternatively, this set of components may be implemented as separate components or groups of components for various purposes. The set of components may be communicatively coupled (e.g., communicatively, directly or indirectly) to various other circuits of UE 120.

[0036] The UE 120 may include at least one antenna 312 in communication with a transmitter 314 and a receiver 316. Alternatively, the transmit and receive antennas may be separate. The UE 120 may also include a processor 320 configured to provide signals to the transmitter 314 and receive signals from the receiver 316, respectively, and to control functionality of the UE 120. The processor 320 may be configured to control functionality of the transmitter 314 and the receiver 316 by causing control signaling through electrical leads to the transmitter 314 and the receiver 316. Similarly, the processor 320 may be configured to control other elements of the UE 120 by causing control signaling through electrical leads connecting the processor 320 to other elements, such as a display or memory. Processor 320 may be embodied in a variety of ways, including, for example, a circuit, at least one processing core, one or more microprocessors with associated digital signal processors, one or more processors without associated digital signal processors, one or more coprocessors, one or more multi-core processors, one or more controllers, processing circuitry, one or more computers, various other processing elements including integrated circuits (e.g., application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and / or the like), or some combination thereof. Thus, although shown as a single processor in FIG. 3, in some example embodiments, processor 320 may comprise multiple processors or processing cores.

[0037] UE 120 may be capable of operating according to one or more air interface standards, communication protocols, modulation types, access types, and / or the like. Signals sent and received by processor 320 may include signaling information according to the applicable cellular system air interface standard and / or any number of different landline or wireless networking technologies, including, without limitation, Wi-Fi, wireless local access network (WLAN) technologies, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11, 802.16, 802.3, ADSL, DOCSIS, and / or the like. Additionally, these signals may include voice data, user-generated data, user-requested data, and / or the like.

[0038] For example, the UE 120 and / or the cellular modem therein may be capable of operating according to various first-generation (1G) communication protocols, second-generation (2G or 2.5G) communication protocols, third-generation (3G) communication protocols, fourth-generation (4G) communication protocols, fifth-generation (5G) communication protocols, Internet Protocol Multimedia Subsystem (IMS) communication protocols (e.g., Session Initiation Protocol (SIP)), and / or the like. For example, the UE 120 may be capable of operating according to 2G wireless communication protocols IS-136, time division multiple access (TDMA), Global System for Mobile Communications (GSM), IS-95, code division multiple access (CDMA), and / or the like. Additionally, for example, the UE 120 may be capable of operating according to 2.5G wireless communication protocols General Packet Radio Service (GPRS), Enhanced Data GSM Environment (EDGE), and / or the like. Additionally, for example, UE 120 may be capable of operating according to a 3G wireless communication protocol, such as Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), Wideband Code Division Multiple Access (WCDMA), Time Division Synchronous Code Division Multiple Access (TD-SCDMA), and / or the like. UE 120 may also be capable of operating according to a 3.9G wireless communication protocol, such as Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), and / or the like. Additionally, for example, UE 120 may be capable of operating according to a 4G wireless communication protocol, such as LTE-Advanced, 5G, and / or the like, and similar wireless communication protocols that may be later developed.

[0039] It will be understood that the processor 320 may include circuitry for implementing the audio / video and logic functions of the UE 120. For example, the processor 320 may comprise a digital signal processor device, a microprocessor device, an analog-to-digital converter, a digital-to-analog converter, and / or the like. The control and signal processing functions of the UE 120 may be allocated among these devices according to their respective capabilities. The processor 320 may further include an internal voice coder (VC) 320a, an internal data modem 320b, and / or the like. Furthermore, the processor 320 may include functionality for operating one or more software programs, which may be stored in memory. Generally, the processor 320 and the stored software instructions may be configured to cause the UE 120 to perform operations. For example, the processor 320 may have the capability to operate a connectivity program, such as a web browser. The connectivity program may enable the UE 120 to send and receive web content, such as location-based content, according to protocols such as the Wireless Application Protocol (WAP), Hypertext Transfer Protocol (HTTP), and / or the like.

[0040] The UE 120 may also include a user interface, including, for example, an earpiece or speaker 324, a ringer 322, a microphone 326, a display 328, a user input interface, and / or the like, which may be operatively coupled to the processor 320. The display 328 may include a touch-sensitive display, as described above, where a user may perform touches and / or gestures to make selections, enter values, and / or the like. The processor 320 may also include user interface circuitry configured to control at least some functions of one or more elements of the user interface, such as the speaker 324, the ringer 322, the microphone 326, the display 328, and / or the like. The processor 320, and / or the user interface circuitry comprising the processor 320, may be configured to control one or more functions of one or more elements of the user interface through computer program instructions, e.g., software and / or firmware, stored in memory accessible to the processor 320, e.g., volatile memory 340, non-volatile memory 342, and / or the like. The UE 120 may include a battery for powering various circuits associated with a mobile terminal, such as a circuit that provides mechanical vibration as a detectable output. A user input interface may comprise devices that allow the UE 120 to receive data, such as a keypad 330 (which may be a virtual keyboard presented on the display 328 or an externally coupled keyboard) and / or other input devices.

[0041] 3, the UE 120 may also include one or more mechanisms for sharing and / or obtaining data. For example, the UE 120 may include a short-range radio frequency (RF) transceiver and / or interrogator 364, whereby data may be shared with and / or obtained from electronic devices according to RF techniques. The UE 120 may include other short-range transceivers, such as an infrared (IR) transceiver 366, a Bluetooth (BT) transceiver 368 using Bluetooth wireless technology, a wireless universal serial bus (USB) transceiver 370, a Bluetooth low energy transceiver, a ZigBee transceiver, an ANT transceiver, a cellular device-to-device transceiver, a wireless local area link transceiver, and / or any other short-range wireless technology. The UE 120, and in particular the short-range transceiver, may have the capability to transmit data to and / or receive data from electronic devices within the vicinity of the UE, e.g., within 10 meters. A UE 120 including a Wi-Fi or wireless local area networking modem may also be capable of transmitting and / or receiving data from electronic devices via various wireless networking techniques, including WLAN techniques such as 6LoWpan, Wi-Fi, Wi-Fi low power, IEEE 802.11 techniques, IEEE 802.15 techniques, IEEE 802.16 techniques, and / or the like.

[0042] The UE 120 may include memory, such as a subscriber identity module (SIM) 338, a removable user identity module (R-UIM), an eUICC, a UICC, and / or the like, which may store information elements associated with a mobile subscriber. In addition to the SIM, the UE 120 may include other removable and / or fixed memory. The UE 120 may include volatile memory 340 and / or nonvolatile memory 342. For example, the volatile memory 340 may include random access memory (RAM), including dynamic and / or static RAM, on-chip or off-chip cache memory, and / or the like. The non-volatile memory 342, which may be embedded and / or removable, may include, for example, read-only memory, flash memory, magnetic storage devices such as hard disks, floppy disk drives, magnetic tape, optical disk drives and / or media, non-volatile random access memory (NVRAM), and / or the like. Like the volatile memory 340, the non-volatile memory 342 may include a cache area for temporary storage of data. At least a portion of the volatile and / or non-volatile memory may be embedded in the processor 320. The memory may store one or more software programs, instructions, information, data, and / or the like that may be used by the UE to perform the operations disclosed herein.

[0043] The memory may comprise an identifier, such as an International Mobile Equipment Identity (IMEI) code, capable of uniquely identifying the UE 120. The memory may comprise an identifier, such as an International Mobile Equipment Identity (IMEI) code, capable of uniquely identifying the UE 120. In an example embodiment, the processor 320 may be configured with computer code stored in the memory 340 and / or 342 to cause the processor 320 to perform the operations disclosed herein.

[0044] Some of the embodiments disclosed herein 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, for example, on memory 340, processor 320, or other electronic components. In some example embodiments, the application logic, software, or instruction set is maintained on any one of a variety of conventional computer-readable media. In the context of this document, a "computer-readable medium" may be any non-transitory medium that can contain, store, communicate, propagate, or transport instructions for use by or in connection with an instruction execution system, UE, or device, such as a computer or data processor circuitry, in the example shown in FIG. 3, and the computer-readable medium may comprise a non-transitory computer-readable storage medium that can contain or store instructions for use by or in connection with an instruction execution system, UE, or device, such as a computer.

[0045] A procedure 400 for accessing a network slice-specific random access channel (RACH) resource pool at a user equipment (UE) 120 is visualized in FIG. 4. When the UE 120 is in a connected mode having an inactive state, the UE 120 starts the procedure at 410 to initiate a random access, RA, procedure for resumption of a radio resource control (RRC) connection. The UE 120 comprises upper and lower layers, such as a non-access stratum (NAS) layer and an access stratum (AS) layer. The NAS layer may initiate the resumption of the RRC connection. In other embodiments, the resumption may be initiated by the AS or any other layer.

[0046] Then, at 420, the non-access stratum (NAS) layer of the inactive UE 120 provides at least one slice identifier to the access stratum (AS) layer. The slice identifier may correspond to a slice selection assistance information (S-NSSAI), which characterizes the service type identified for slicing purposes. The S-NSSAI may also be included in a list of S-NSSAIs. The S-NSSAI may comprise a standardized slice / service type, SST. Furthermore, the S-NSSAI may also comprise an operator-defined access category corresponding to the network slice. Standardized SST values, defined for the purpose of establishing global interoperability for slicing so that public land mobile networks (PLMNs) can more efficiently support roaming use cases for the most commonly used slices / service types, are defined in TS 23.501 as follows:

[0047] [Table 1]

[0048] The services shown in this table for each SST value may also be supported by other SSTs.

[0049] The unified access control framework for 5G further defines access categories and access identities to enable categorization of any access attempt. When a user UE 120 initiates an access attempt, the UE 120 determines one or more access identities and one access category from a set of standardized access identities. The set of access categories distinguishes between standardized access categories and operator-defined access categories to be associated with the access attempt. Signaling currently supports access categories ranging from 0 to 63. TS 24.501 specifies how each UE's access attempt is categorized at the NAS layer. There are 32 access categories reserved for operator use, which can be associated with a slice identifier. Based on the operator-defined set of access categories, the UE 120 determines whether the access attempt to a given slice is authorized based on the broadcasted barring information, which is further defined in TS 38.331.

[0050] After the AS layer receives the at least one slice identifier, the AS layer determines which network slice to use for the RRC connection based on the provided at least one slice identifier at 430. Then, based on this information, the UE 120 initiates an RA procedure.

[0051] There are two types of RA procedure: a four-step RA type with message MSG1 and a two-step RA type with message MSGA. The UE 120 selects the type of random access at the start of the RA procedure based on the network configuration, which is sent to the UE 120 in advance by the network by common or dedicated signaling.

[0052] The four-step RA type MSG1 includes a preamble on the physical RACH (PRACH). After MSG1 transmission, the UE 120 monitors for a response from the network, e.g., from a base station or gNB, within a configured time window. For contention-free RA (CFRA), a dedicated preamble for MSG1 transmission is assigned by the network. Upon receiving an RA response from the network, the UE 120 terminates the RA procedure. For contention-based RA (CBRA), upon receiving an RA response, the UE 120 sends a message MSG3 with a scheduled uplink grant in the response and monitors contention resolution. If contention resolution is not successful after MSG3 (re)transmission, the UE 120 reverts to MSG1 transmission.

[0053] The two-step RA type MSGA includes a preamble on the PRACH and a payload on the Primary Uplink Shared Channel (PUSCH). After the MSGA transmission, the UE 120 monitors for a response from the network within a configured time window. For CFRA, a dedicated preamble and PUSCH resources are configured for the MSGA transmission, and the UE 120 terminates the RA procedure as soon as it receives a network response. For CBRA, the UE 120 terminates the RA procedure if contention resolution is successful as soon as it receives a network response.

[0054] The RA procedure may result in the end 440 of the procedure 400. In this situation, the UE 120 applies the RACH configuration parameters corresponding to the at least one determined network slice for the RA procedure and for preamble transmission within this RA procedure as described above.

[0055] As described earlier, the S-NSSAI is provided from the NAS layer to the AS layer as the AS layer performs the RA procedure, and the S-NSSAI is handled by the NAS layer. However, which S-NSSAI is sent from the NAS layer to the AS layer may vary depending on several factors.

[0056] For example, when UE 120 is in idle mode (which is not the focus of this disclosure), the NAS layer of UE 120 provides a list of S-NSSAIs to the AS layer according to the process described in clause 4.6.2.3 of TS 24.501, Rel-16, V16.8.0. Alternatively, the NAS layer can provide a list of S-NSSAIs for RACH-specific purposes, i.e., the S-NSSAIs are provided together with or separately from the access category and access identity provided for normal access attempts. Clause 4.6.2.3 of TS 24.501, Rel-16, V16.8.0 is described below.

[0057] Start of quotation 4.6.2.3 Providing NSSAI to lower layers in 5GMM idle mode The UE NAS layer may provide the NSSAI (requested NSSAI or allowed NSSAI) to the lower layer when the UE sends an initial NAS message in 5GMM idle mode. The AMF may indicate the NSSAI inclusion mode in which the UE shall operate, if any, through the current access in the current PLMN or SNPN via the NSSAI Inclusion Mode IE in the Registration Accept message (see sub-clauses 5.5.1.2.4 and 5.5.1.3.4), where the NSSAI inclusion mode is selected from the following NSSAI inclusion modes as stated in Table 4.6.2.3.1:

[0058] [Table 2] UE is a) Indicated by the AMF if the AMF included the NSSAI Inclusion Mode IE in the Registration Accept message, or b) If the NSSAI Inclusion Mode IE was not included in the Registration Accept message, as determined by the UE, The NSSAI inclusion mode shall be stored together with the current PLMN or SNPN identity and access type in non-volatile memory in the ME as specified in Annex C. The UE shall apply the NSSAI inclusion mode received in the Registration Accept message via Current Access within the Current PLMN and its equivalent PLMN, or Current SNPN, if any, if it is within the Current Registration Area. When the UE performs a registration procedure to a PLMN or SNPN that is not a PLMN in its current registration area, and the UE has no NSSAI inclusion mode for the PLMN or SNPN stored in non-volatile memory in the ME, the UE shall provide the following to lower layers: a) no NSSAI if the UE is performing the registration procedure through 3GPP access, or b) The requested NSSAI if the UE is performing the registration procedure via non-3GPP access. When the UE performs the registration procedure after an inter-system change from S1 mode to N1 mode, if the UE has no NSSAI inclusion mode for the PLMN stored in the non-volatile memory in the ME and the registration procedure is performed through 3GPP access, the UE shall not provide any NSSAI to lower layers through 3GPP access.

[0059] End of quote

[0060] In some embodiments, when a UE 120 in 5GMM idle mode sends an initial NAS message, the UE NAS layer may provide the UE AS layer with one set of S-NSSAIs (or no S-NSSAIs) in accordance with clause 4.6.2.3 of TS 24.501, Rel-16, V16.8.0, and additionally with another set of S-NSSAIs to which the initial NAS message pertains (e.g., the other set of S-NSSAIs may be determined assuming that the UE 120 is configured with NSSAI inclusion mode A or B, regardless of the actual NSSAI inclusion mode in which the UE 120 is operating). This may be necessary, for example, because if the UE 120 were configured with NSSAI inclusion mode D, the UE NAS layer would not send S-NSSAIs to the UE AS layer in accordance with clause 4.6.2.3 of TS 24.501, Rel-16, V16.8.0.

[0061] As described above, when UE 120 is in connected mode with an RRC inactivity indication (i.e., inactive state or inactive mode), the NAS layer of UE 120 in the inactive state provides a list of S-NSSAIs to the AS layer when the NAS layer initiates the resumption of the RRC connection. The S-NSSAIs to be included in the list of S-NSSAIs may further vary depending on how the resumption of the RRC connection is initiated.

[0062] For example, if the resumption of the RRC connection is triggered by pending uplink user data (to be transmitted by at least one packet of one or more protocol data unit (PDU) sessions), the S-NSSAI associated with the PDU session is provided to the AS layer. However, if the resumption of the RRC connection is triggered by a UE-initiated 5G Mobility Management (5GMM) procedure, there are two options: If the 5GMM procedure is a UE-initiated NAS transport procedure for delivering one or more 5G Session Management (5GSM) messages, the S-NSSAI associated with the 5GSM messages is provided to the AS layer. If the 5GMM procedure is a registration procedure or a service request procedure, the S-NSSAI provided to the AS layer is determined in accordance with the procedure described in clause 4.6.2.3 of TS 24.501 (it can be assumed that the specific NSSAI inclusion mode is independent of the actual NSSAI inclusion mode in which the UE 120 is operating).

[0063] In any of the described cases, the AS layer ultimately uses the list of S-NSSAIs provided by the NAS layer for the RA procedure. Therefore, the AS layer can select the corresponding RACH configuration parameters broadcast from the BS based on the S-NSSAIs provided by the NAS layer. This is also described in more detail below.

[0064] 5 illustrates a procedure 500 for using a group of network slices provided by a NAS for communication between a base station 510 and a UE 120, the UE 120 comprising an AS layer 520 and a NAS layer 520, in a connected mode having an inactive state. The base station, for example, and a gNB 510, determines the need to activate 540 optimized RA control within the cell between a common resource pool and a slice-specific resource pool. The activation can be an internal operation within the gNB 510 based on a received indication for a slice group deserving dedicated resources (a dedicated RA pool) and / or based on an indication of resource sharing or partitioning.

[0065] The gNB 510 then configures a specific RACH configuration for each slice or slice group. Thus, the gNB 510 determines which slices require prioritization by determining the slice by the S-NSSAI, (a set of) standardized SSTs, or (a set of) operator-defined access categories corresponding to the slice. Furthermore, the gNB 510 determines which RA parameters need to be set to slice-specific values ​​(e.g., scaling factor for back-off indicator, power ramping step, back-off timer, random access opportunity, PRACH configuration index, PRACH configuration frame offset, PRACH configuration period scaling, target power for MSGA or MSG1, target reference signal received power (RSRP) for MSGA or MSG1, RSRP threshold for MSGA or MSG1, maximum transmit power, minimum transmit power, etc.).

[0066] The gNB 510 generates a corresponding slice-specific RACH configuration with the RACH parameters for each slice group as determined. At 545, this information is broadcast to the UE 120 in a system information block (SIB) message. At 550, the AS layer 520 obtains this information about the slice-specific RACH configuration and stores it in a memory, for example.

[0067] When an RA procedure is initiated to return from an RRC inactive state to an active state, the NAS layer 530 transmits a list of S-NSSAIs to the UE AS layer 520 at 555. This may be the case, for example, if higher layers determine that data packets should be uploaded, e.g., for a video upload or a message to be sent; if the UE 120 needs to establish a new PDU session (i.e., send the 5GSM message "PDU Session Establishment Request"); or if the UE 120 moves outside of its current registration area and therefore needs to initiate a registration procedure. The NAS layer 530 is then initiated to provide the AS layer 520 with an S-NSSAI corresponding to a specific purpose. In the embodiment shown, the S-NSSAI included in the transmitted list corresponds to a network slice group. Network slices may be grouped based on their purpose, location, or other common characteristics. The purpose may be RA resource isolation or prioritization.

[0068] At 560, the AS layer 520 holds the information received from the gNB 510 at 545 and from the NAS layer 530 at 555. Using this information, the AS layer 520 initiates an initiated RA procedure at 570 and uses the list of received S-NSSAIs to determine which RACH configuration and which parameters apply at 580. Finally, the RA parameters of the determined RA configuration are sent in MSG1 or MSGA, for example, in the preamble.

[0069] In some embodiments, the UE 120 may be configured with information about a mapping between one or more S-NSSAIs and network slice group identities. The mapping information may be pre-configured in the UE 120 or may be received from the network. If the mapping information is maintained within the NAS layer 530, the NAS layer 530 maps the list of S-NSSAIs to network slice group identities and provides the network slice group identities to the AS layer 520. On the other hand, if the mapping information is maintained within the AS layer 520, the NAS layer 530 provides the list of S-NSSAIs to the AS layer 520, which performs the mapping and determines which RACH configuration should be applied based on the mapped network slice group identities.

[0070] In some embodiments, without loss of generality, what is applicable to the gNB 510 may also apply to the eNB supporting access to the 5G core network.

[0071] FIG. 6 shows a simplified block diagram of a network node 411 according to some embodiments. The network node 411 may be a base station combined with an MME or an AMF. The network node 411 has an antenna 415 for transmitting and receiving radio signals. A radio frequency (RF) transceiver module 414 coupled to the antenna receives RF signals from the antenna 415, converts them to baseband signals, and sends them to a processor 413. The RF transceiver 414 also converts the received baseband signals from the processor 413, converts them to RF signals, and sends them to the antenna 415. The processor 413 processes the received baseband signals and invokes different function modules to perform functions in the network node 411. A memory 412 stores program instructions and data 420 for controlling the operation of the network node 411. In the example of FIG. 6, the network node 411 also includes a protocol stack 480 and a set of control function modules and circuits 490 that implement the mobility management functions described above. Suitable processors include, by way of example, special purpose processors, digital signal processors (DSPs), multiple microprocessors, one or more microprocessors associated with a DSP core, controllers, microcontrollers, application specific integrated circuits (ASICs), field programmable gate array (FPGA) circuits, and other types of integrated circuits (ICs), and / or state machines. Other nodes of the communications network, such as servers in an EDN, are appropriately equipped, i.e., with similar internal components. Instead of the transceiver module 414 and antenna 415, these nodes may use wired communications techniques to communicate with other network nodes.

[0072] In general, the routines executed to implement the embodiments may be referred to herein as "computer program code" or simply "program code," whether implemented as part of an operating system or as a specific application, component, program, object, module, or sequence of instructions, or even a subset thereof. Program code typically resides at various times in various memory and storage devices within a computer and comprises computer-readable instructions that, when read and executed by one or more processors within the computer, cause the computer to perform operations and / or actions necessary to carry out elements embodying various aspects of embodiments of the present invention. Computer-readable program instructions for carrying out operations of embodiments of the present invention may be source code or object code, for example, written in assembly language or any combination of one or more programming languages.

[0073] In some alternative embodiments, the functions and / or acts specified in the flowcharts, sequence diagrams, and / or block diagrams may be reordered, processed sequentially, and / or processed simultaneously without departing from the scope of the invention. Additionally, any of the flowcharts, sequence diagrams, and / or block diagrams may include more or fewer blocks than illustrated, consistent with an embodiment of the invention.

[0074] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the present disclosure. It will be further understood that, as used herein, the terms "comprise" and / or "comprising" specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not exclude the presence of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Furthermore, to the extent that "includes," "having," "has," "with," "comprised of," or variations thereof, are used in either the Detailed Description or the Claims, such terms are intended to be inclusive in the same manner as the term "comprising."

[0075] While the description of the various embodiments is fully illustrative of the invention, and these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will readily occur to those skilled in the art. Thus, the invention in its broader aspects is not limited to the specific details, representative UE and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicants' general inventive concept.

Claims

1. 1. A method for accessing a network slice specific random access channel (RACH) resource pool in a user equipment (UE), wherein the UE is in a connected mode having an inactive state and the method includes initiating a random access (RA) procedure for resumption of a radio resource control (RRC) connection; providing at least one slice identifier from a non-access stratum, NAS, layer to an access stratum, AS, layer; determining, by the AS layer, at least one network slice to use for the RRC connection based on the provided at least one slice identifier; A method comprising:

2. 2. The method of claim 1, wherein providing the at least one slice identifier is performed in response to an RA procedure initiated by at least one uplink user data packet of one or more protocol data units (PDUs) of a session, and the at least one slice identifier is associated with the PDU session.

3. 3. The method of claim 1 or 2, wherein providing the at least one slice identifier is further performed in response to the RA procedure being a UE-initiated 5G Mobility Management (5GMM) procedure and the 5GMM procedure being initiated by a UE-initiated NAS transport procedure for delivering one or more 5G Session Management (5GSM) messages, and the at least one slice identifier is associated with the 5GSM messages.

4. The method according to any one of claims 1 to 3, wherein the at least one slice identifier corresponds to a single network slice selection assistance information, S-NSSAI, with a standardized slice / service type, SST.

5. 5. The method of claim 4, wherein the S-NSSAI further comprises an operator-defined access category corresponding to a network slice.

6. applying RACH configuration parameters corresponding to the at least one determined network slice to the RA procedure selection and preamble transmission. The method of any one of claims 1 to 5, further comprising:

7. A user equipment, UE, for accessing a slice-specific random access channel, RACH, resource pool, wherein the UE is in a connected mode having an inactive state and initiates a random access, RA, procedure for resumption of a radio resource control, RRC, connection; providing at least one slice identifier from a non-access stratum, NAS, layer to an access stratum, AS, layer; determining, by the AS layer, at least one network slice to use for the RRC connection based on the provided at least one slice identifier; A UE configured to:

8. 8. The UE of claim 7, wherein the UE is configured to provide at least one slice identifier in response to the RA procedure being initiated by a UE-initiated 5G Mobility Management, 5GMM, procedure and the 5GMM procedure being a UE-initiated Non-Access Stratum, NAS, transport procedure for delivering one or more 5G Session Management, 5GSM, messages, and the at least one slice identifier is associated with the 5GSM message.

9. 9. The UE of claim 7 or 8, wherein the UE is further configured to provide at least one slice identifier in response to the RA procedure being initiated by a UE-initiated 5G Mobility Management, 5GMM, procedure and the 5GMM procedure being a UE-initiated Non-Access Stratum, NAS, transport procedure for delivering one or more 5G Session Management, 5GSM, messages, and the at least one slice identifier is associated with the 5GSM message.

10. 10. The UE according to any one of claims 7 to 9, wherein the at least one slice identifier corresponds to a single network slice selection assistance information, S-NSSAI, with a standardized slice / service type, SST.

11. The UE of claim 10, wherein the S-NSSAI further comprises an operator-defined access category corresponding to a network slice.

12. The UE applying RACH configuration parameters corresponding to the at least one determined network slice to the RA procedure selection and preamble transmission. The UE of claim 11 further configured to:

13. A base station, BS, for resumption of a Radio Resource Control, RRC, connection with a user equipment, UE, according to any one of claims 7 to 12, comprising: Configuring a network slice-specific random access channel (RACH) configuration for each network slice or network slice group, wherein the RACH configuration is associated with a slice identifier; transmitting the RACH configuration to the UE; receiving a preamble transmission from the UE comprising RACH configuration parameters corresponding to the transmitted RACH configuration; A BS configured to perform the following.

14. A wireless communication system comprising a base station (BS) according to claim 13 and a user equipment (UE) according to any one of claims 7 to 12, In the BS, configuring a network slice-specific random access channel (RACH) configuration for each network slice or network slice group, wherein the RACH configuration is associated with a slice identifier; transmitting the RACH configuration from the BS to the UE; providing at least one slice identifier from a non-access stratum (NAS) layer of the UE to an access stratum (AS) layer of the UE; determining, by the AS layer of the UE, a network slice or a group of network slices to use for the RRC connection based on the provided at least one slice identifier; transmitting a preamble from the UE to the BS, the preamble comprising RACH configuration parameters corresponding to the determined RACH configuration; A system configured to:

15. A computer program comprising computer program code which, when executed by a computer, causes at least one computer to perform the method according to any one of claims 1 to 6.

16. A computer program product comprising program instructions stored on a computer readable medium, said program performing the method of any one of claims 1 to 6 when said program is run on a computer.

Images