Addressing core network connectivity failures

Abstract

Generally, the present subject matter relates to handling core network connectivity failures. In some implementations, upon connectivity down between a gNodeB and a 5G core network, a gNodeB can be transitioned to an active state so that the gNodeB can provide support for non-standalone (NSA) user equipment (UE) upon connectivity down between the gNodeB and the 5G core network.

Description

[Technical Field]

[0001] In some implementations, the present subject matter relates to communication systems, and in particular to dealing with core network connectivity failures. [Background technology]

[0002] In today's world, cellular networks provide on-demand communication capabilities to individuals and business entities. Typically, cellular networks are wireless networks that can be distributed over a terrestrial area called a cell. Each such cell is served by at least one fixed-location transceiver, referred to as a cell site or base station. Each cell can use a different set of frequencies from its neighboring cells to avoid interference and provide improved service within each cell. Together, the cells provide wireless coverage over a wide geographic area, allowing numerous mobile phones and / or other wireless devices or portable transceivers to communicate with each other and with fixed transceivers and phones anywhere in the network. Such communication is performed through base stations, even when a communicating mobile transceiver passes through more than one cell. Major wireless communication providers deploy such cell sites worldwide, allowing communicating mobile phones and mobile computing devices to connect to public switched telephone networks and the public Internet.

[0003] A mobile phone is a portable telephone that can receive and / or make telephone and / or data calls through a cell site or communication tower by using radio waves to transmit signals to and from the mobile phone. From the perspective of a large number of mobile phone users, current mobile phone networks offer limited and shared resources. In this regard, cell sites and handsets can change frequencies and use low-power transmitters to allow simultaneous use of the network by many callers with less interference. Coverage by a cell site can depend on the particular geographic location and / or the number of users that can potentially use the network. For example, in a city, a cell site may have a range of up to about 1 / 2 mile. In suburban areas, the range may be as long as 5 miles. In some areas, users can receive signals from cell sites as far away as 25 miles.

[0004] The following are some examples of digital cellular technologies used by communications providers: Global System for Mobile Communications ("GSM"), General Packet Radio Service ("GPRS"), cdmaOne, CDMA2000, Evolution-Data Optimized ("EV-DO"), Enhanced Data Rates for GSM Evolution ("EDGE"), Universal Mobile Telecommunications System ("UMTS"), Digital Enhanced Cordless Telecommunications ("DECT"), Digital AMPS ("IS-136 / TDMA"), and Integrated Digital Enhanced Network ("iDEN"). Long Term Evolution or 4G LTE, developed by the Third Generation Partnership Project ("3GPP") standards organization, is a standard for high-speed data wireless communications for mobile phones and data terminals. 5G standards are currently being developed and deployed. 3GPP cellular technologies such as LTE and 5G NR are evolutions of previous generations of 3GPP technologies such as GSM / EDGE and UMTS / HSPA digital cellular technologies, and allow for increased capacity and speeds by using different air interfaces along with core network improvements.

[0005] A cellular network may be divided into a radio access network and a core network. The radio access network (RAN) may include network functions capable of handling radio layer communication processing. The core network may include network functions capable of handling higher layer communication (e.g., Internet Protocol (IP), transport layer, and application layer). In some cases, the RAN function may be divided into a baseband unit function and a radio unit function. Here, the radio unit connected to the baseband unit via a fronthaul network may be responsible for lower layer processing, for example, of the radio physical layer, and the baseband unit may be responsible for higher layer radio protocols (e.g., MAC, RLC, etc.). Summary of the Invention [Problem to be solved by the invention]

[0006] In a 5G wireless communication system, an F1 interface is set up between a base station's distributed unit (DU) and a base station's aggregation unit (CU) to properly support communications between the base station. The F1 interface is set up in accordance with 3GPP standards (including 3GPP TS 38.401 "NG-RAN; Architecture description" and 3GPP TS 38.473 "NG-RAN; F1 application protocol (F1AP)"). However, according to the 3GPP standards, if a base station (e.g., its CU) does not have connectivity to a 5G core network (5GC), the base station cannot provide service to mobile phones and other user equipment (UE) attempting to connect to a standalone (SA) 5G network. A non-standalone (NSA) device, a UE, is capable of 5G communications but is supported by the 4G infrastructure and therefore does not depend on a base station with 5GC connectivity to be able to communicate over a 5G wireless communication system. [Means for solving the problem]

[0007] In some implementations, the present subject matter relates to a computer-implemented method that may include, upon a connection down between the gNodeB and a 5G core network, transitioning a gNodeB to an active state such that the gNodeB can provide support for non-standalone (NSA) user equipment (UE) upon connection down between the gNodeB and the 5G core network.

[0008] The method may allow the F1 interface to be set up despite a core network connection failure, so that the DU may be available to serve at least some UEs despite the core network connectivity failure, which may reduce the burden on one or more other DUs in the base station and / or one or more DUs in other base stations that would otherwise have to serve those UEs.

[0009] In some implementations, the current subject may include one or more of the following optional features:

[0010] In some implementations, transitioning the gNodeB to the active state may include the active state being set in a distributed unit (DU) of the gNodeB in response to information received by the DU from a aggregation unit (CU) of the gNodeB.

[0011] In some implementations, transitioning the gNodeB to the active state may include setting up an F1 interface between a CU of the gNodeB and a DU of the gNodeB. Further, the F1 interface may be set up between the CU of the gNodeB and the DU of the gNodeB without performing System Information Block Type 1 (SIB1) scheduling, or the F1 interface may be set up between the CU of the gNodeB and the DU of the gNodeB by performing SIB1 without a 5G System (5GS) Tracking Area Code (TAC).

[0012] In some implementations, transitioning the gNodeB to the active state may include sending a GNB-CU Configuration Update message from the CU of the gNodeB to the DU of the gNodeB. Further, the list of cells to be activated included in the GNB-CU Configuration Update message may indicate to the DU that the gNodeB can provide support for NSA UEs, and including a list of cells to be forbidden in the GNB-CU Configuration Update message or excluding the available PLMN list from the GNB-CU Configuration Update message may indicate to the DU that the gNodeB cannot provide support for standalone (SA) UEs.

[0013] In some implementations, the operations may further include, upon connection down between the gNodeB and the 5G core network, transitioning the gNodeB to an active state, enabling the gNodeB to provide support for the SA UE in response to connection between the gNodeB and the 5G core network becoming available. Further, transitioning the gNodeB to an active state to enable the gNodeB to provide support for the NSA UE may include sending a first GNB CU Configuration Update message from a CU of the gNodeB to a DU of the gNodeB, enabling the gNodeB to provide support for the SA UE may include sending a second GNB CU Configuration Update message from the CU of the gNodeB to a DU of the gNodeB, and / or the gNodeB may be transitioned to an active state without performing SIB1 scheduling or performing SIB1 scheduling without 5GS TAC upon connection down between the gNodeB and the 5G core network, and transitioning the gNodeB to the active state to enable the gNodeB to provide support for the SA UE may include performing SIB1 scheduling. Furthermore, the first list of cells to be activated included in the first GNB-CU configuration update message can indicate to the DU that the gNodeB can provide support for NSA UEs, the first list of cells to be prohibited included in the first GNB-CU configuration update message or the available PLMN list excluded from the first GNB-CU configuration update message can indicate to the DU that the gNodeB cannot provide support for SA UEs, and the second list of cells to be activated and / or the available PLMN list included in the second GNB-CU configuration update message can indicate to the DU that the gNodeB can provide support for SA UEs.

[0014] In some implementations, a gNodeB may include at least one processor and at least one non-transitory storage medium.

[0015] Non-transitory computer program products (i.e., physically embodied computer program products) storing instructions that, when executed by one or more data processors of one or more computing systems, cause at least one data processor to perform the operations described herein are also described. Similarly, computer systems are described that may include one or more data processors and memory coupled to the one or more data processors. The memory may store, on a temporary or permanent basis, instructions that cause at least one processor to perform one or more of the operations described herein. In addition, methods may be implemented by one or more data processors within a single computing system or distributed across two or more computing systems. Such computing systems may be connected to exchange data and / or commands or other instructions, etc., over one or more connections (including, but not limited to, connections over a network (e.g., the Internet, a wireless wide area network, a local area network, a wide area network, a wired network, etc.)), such as via a direct connection between one or more of the multiple computing systems.

[0016] Details of one or more variations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features and advantages of the subject matter described herein will be apparent from the description and drawings, and from the claims. [Brief explanation of the drawings]

[0017] The following accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate certain aspects of the presently disclosed subject matter and, together with the description, serve to explain some of the principles associated with the disclosed implementations.

[0018] FIG. 1a illustrates an exemplary conventional "long term evolution" ("LTE") communications system.

[0019] FIG. 1b shows further details of the exemplary LTE system shown in FIG. 1a.

[0020] FIG. 1c shows additional details of the "evolved packet core" of the exemplary LTE system shown in FIG. 1a.

[0021] FIG. 1d illustrates an exemplary "evolved Node B" for the exemplary LTE system shown in FIG. 1a.

[0022] FIG. 2 illustrates further details of the "evolved Node B" shown in FIGS. 1a-d.

[0023] FIG. 3 illustrates an exemplary virtual radio access network according to some implementations of the current subject matter.

[0024] FIG. 4 shows an exemplary 3GPP split architecture for providing its users with use of higher frequency bands.

[0025] FIG. 5a illustrates an exemplary 5G wireless communication system.

[0026] FIG. 5b shows an example layer architecture for a split gNB and / or a split ng-eNB (e.g., a “next generation eNB” that may be connected to 5GC).

[0027] Figure 5c shows an exemplary functional split in the gNB architecture shown in Figures 5a-b.

[0028] FIG. 6 illustrates an exemplary method for addressing core network connectivity failures according to some implementations of the current subject matter.

[0029] FIG. 7a illustrates an exemplary system configured to address core network connectivity failures and an exemplary process by which F1 setup begins with 5G core network connectivity down, according to some implementations of the current subject matter.

[0030] FIG. 7b illustrates the system of FIG. 7a and an exemplary process in which F1 setup begins with 5G core network connectivity up, according to some implementations of the current subject matter.

[0031] FIG. 8 illustrates an exemplary system according to some implementations of the current subject matter.

[0032] FIG. 9 illustrates an exemplary method according to some implementations of the current subject matter. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present subject matter can provide systems and methods that can be implemented in wireless communication systems. Such systems can include various wireless communication systems, including 5G New Radio communication systems, "long term evolution" communication systems, and the like.

[0034] Generally, the present subject matter relates to handling core network connectivity failures.

[0035] In some implementations, an F1 interface may be set up between a centralized unit (CU) of a base station (e.g., a gNodeB) of a 5G wireless communication system and a distributed unit (DU) of the base station, even if the base station does not have connectivity to a core network of the 5G wireless communication system. Currently, under 3GPP standards, a UE cannot set up a connection with a standalone 5G wireless communication system if the base station does not have connectivity to the 5G core network. As a result, the DU cannot provide service to standalone (SA) user equipment (UE), which relies on a base station connected to the 5G core network to communicate over the wireless communication system. Thus, the DU is underutilized, at least with respect to those UEs.

[0036] The F1 interface that is set up despite the core network connectivity failure can allow the DU to transition to an active state that enables the DU to provide service to a subset of UEs that do not rely on a base station connected to the 5G core network to communicate over the wireless communication system (e.g., non-standalone (NSA) devices as a subset of UEs). In this way, the DU at the base station becomes available to serve at least some UEs that wish to communicate over the 5G wireless communication system despite the core network connectivity failure, reducing the burden on one or more other DUs at the base station and / or one or more DUs at other base stations that would normally have to serve those UEs. Once connectivity is restored (or established in the initial instance) between the base station and the 5G core network, the DU can provide service to the remaining UEs (i.e., UEs (e.g., SA devices) that rely on a base station connected to the 5G core network to communicate over the 5G wireless communication system). In this way, the DU is configured to provide services for as many UEs as possible when the F1 interface is set up, and the services provided by the DU are later expanded to additional UEs when 5G core network connectivity is restored (or established).

[0037] If the base station has connectivity to the 5G core network at the time of F1 startup, the F1 interface may be set up according to 3GPP standards, and the DU can provide services to NSA UEs and SA UEs. In this manner, the F1 interface can be set up regardless of whether the UE relies on a base station connected to the 5G core network to communicate over a wireless communication system. In this manner, the DU can be configured to provide services for as many UEs as possible when the F1 interface is set up.

[0038] In some implementations, the subset of UEs that the DU can serve despite a lack of base station-core network connectivity may include 5G-capable non-standalone (NSA) devices. Furthermore, the base station may include a 5G base station (e.g., a gNodeB), and the core network may include a 5G core network (5GC). 5G-capable NSA devices are configured to be supported by 4G infrastructure and not depend on a base station having connectivity to the 5GC to enable communication over a 5G wireless communication system. In this manner, an F1 interface set up between the CU and DU of a base station may enable the NSA devices to communicate with the DU for communication over a 5G wireless communication system when the base station does not currently have connectivity to the 5GC. Once connectivity is restored (or established in an initial instance) between the base station and the 5G core network, the DU can serve the remaining UEs (i.e., standalone (SA) devices that rely on a base station connected to the 5G core network to communicate over a 5G wireless communication system).

[0039] 3GPP standards that define one or more aspects related to the present subject matter include 3GPP TS 38.401 "NG-RAN; Architecture description" and 3GPP TS 38.473 "NG-RAN; F1 application protocol (F1AP)". O-RAN Alliance standards may also be related to one or more aspects of the present subject matter.

[0040] One or more aspects of the present subject matter may be integrated into transmitter and / or receiver components of a base station (e.g., gNodeB, eNodeB, etc.) in such communication systems. The following is a general discussion of long-term evolution communication systems and 5G New Radio communication systems. I. "Long-term evolution" communication systems

[0041] 1a-c and 2 illustrate an exemplary conventional long-term evolution ("LTE") communication system 100 along with its various components. LTE systems, or 4G LTE, as they are commercially known, conform to standards for high-speed data wireless communications for mobile phones and data terminals. The standards are an evolution of GSM / EDGE ("Global System for Mobile Communications" / "Enhanced Data rates for GSM Evolution") and UMTS / HSPA ("Universal Mobile Telecommunications System" / "High Speed ​​Packet Access") network technologies. The standards were developed by 3GPP ("3rd Generation Partnership Project").

[0042] As shown in FIG. 1a, system 100 may include an “evolved universal terrestrial radio access network” (“EUTRAN”) 102, an “evolved packet core” (“EPC”) 108, and a “packet data network” (“PDN”) 101 through which EUTRAN 102 and EPC 108 provide communication between user equipment 104 and PDN 101. EUTRAN 102 may include multiple “evolved Node Bs” (“eNodeBs” or “ENODEBs” or “enodeb” or “eNBs”) or base stations 106(a, b, c) (as shown in FIG. 1b) that provide communication capabilities to multiple user equipment 104(a, b, c). User equipment 104 may be a mobile phone, a smartphone, a tablet, a personal computer, a personal digital assistant (“PDA”), a server, a data terminal, and / or any other type of user equipment, and / or any combination thereof. User equipment 104 can connect to the EPC 108 and therefore the PDN 101 via any eNodeB 106. Typically, user equipment 104 can connect to the eNodeB 106 that is closest in distance. In the LTE system 100, the EUTRAN 102 and the EPC 108 cooperate to provide connectivity, mobility, and services to user equipment 104.

[0043] Figure 1b illustrates further details of the network 100 shown in Figure 1a. As previously mentioned, the EUTRAN 102 includes multiple eNodeBs 106, also known as cell sites. The eNodeBs 106 provide radio functionality and perform key control functions, including scheduling of air link resources or radio resource management, active mode mobility or handover, and admission control for services. The eNodeBs 106 are responsible for selecting which mobility management entity (MME, as shown in Figure 1c) serves the user equipment 104 and for protocol features such as header compression and encryption. The eNodeBs 106 that make up the EUTRAN 102 cooperate with each other for radio resource management and handover.

[0044] Communication between the user equipment 104 and the eNodeB 106 occurs over an air interface 122 (also known as the "LTE-Uu" interface). As shown in FIG. 1b, the air interface 122 provides communication between the user equipment 104b and the eNodeB 106a. The air interface 122 uses Orthogonal Frequency Division Multiple Access ("OFDMA") and Single-Carrier Frequency Division Multiple Access ("SC-FDMA"), an OFDMA variant, on the downlink and uplink, respectively. OFDMA enables the use of multiple known antenna technologies, such as "Multiple Input Multiple Output" ("MIMO").

[0045] The air interface 122 uses various protocols, including radio resource control ("RRC") for signaling between the user equipment 104 and the eNodeB 106 and non-access stratum ("NAS") for signaling between the user equipment 104 and the MME (as shown in FIG. 1c). In addition to signaling, user traffic is transferred between the user equipment 104 and the eNodeB 106. Both signaling and traffic in the system 100 are carried by physical layer ("PHY") channels.

[0046] Multiple eNodeBs 106 may be interconnected with each other using X2 interfaces 130(a, b, c). As shown in FIG. 1b, X2 interface 130a provides interconnection between eNodeB 106a and eNodeB 106b, X2 interface 130b provides interconnection between eNodeB 106a and eNodeB 106c, and X2 interface 130c provides interconnection between eNodeB 106b and eNodeB 106c. The X2 interfaces may be established between two eNodeBs to provide for the exchange of signals that may include load- or interference-related information and handover-related information. The eNodeBs 106 communicate with the “evolved packet core” 108 via S1 interfaces 124(a, b, c). The S1 interface 124 may be divided into two interfaces: One is the control plane (shown in FIG. 1c as control plane interface (S1-MME interface) 128) and the other is the user plane (shown in FIG. 1c as user plane interface (S1-U interface) 125).

[0047] The EPC 108 establishes and enables "Quality of Service" ("QoS") for user services and allows the user equipment 104 to maintain a consistent Internet Protocol ("IP") address while moving, where each node in the network 100 has its own IP address. The EPC 108 is designed to work with legacy wireless networks. The EPC 108 is also designed to separate the control plane (i.e., signaling) and user plane (i.e., traffic) in the core network architecture, allowing for greater flexibility in implementation and independent scalability of control and user data functions.

[0048] The architecture of the EPC 108, which is for packet data, is shown in more detail in Figure 1c. The EPC 108 includes a Serving Gateway (S-GW) 110, a PDN Gateway (P-GW) 112, a Mobility Management Entity ("MME") 114, a Home Subscriber Server ("HSS") 116 (the subscriber database for the EPC 108), and a Policy Control and Charging Rules Function ("PCRF") 118. Some of these (such as the S-GW, P-GW, MME, and HSS) are often combined into a node according to the manufacturer's implementation.

[0049] The S-GW 110 functions as an IP packet data router and is the user equipment's bearer path anchor in the EPC 108. Thus, as the user equipment moves from one eNodeB 106 to another during mobility operation, the S-GW 110 remains the same, and the bearer path towards the EUTRAN 102 is switched to talk to the new eNodeB 106 serving the user equipment 104. If the user equipment 104 moves to the domain of another S-GW 110, the MME 114 forwards all of the user equipment's bearer paths to the new S-GW. The S-GW 110 establishes bearer paths for the user equipment to one or more P-GWs 112. When downstream data is received for an idle user equipment, the S-GW 110 buffers the downstream packets and requests the MME 114 to identify and re-establish the bearer path to and through the EUTRAN 102.

[0050] The P-GW 112 is the gateway between the EPC 108 (and thus the user equipment 104 and EUTRAN 102) and the PDN 101 (shown in FIG. 1a). The P-GW 112 acts as a router for user traffic and performs functions on behalf of the user equipment. These include IP address allocation for the user equipment, packet filtering of downstream user traffic to ensure it is placed on the appropriate bearer path, and enabling downstream QoS, including data rate. Depending on the services a subscriber is using, there may be multiple user data bearer paths between the user equipment 104 and the P-GW 112. A subscriber can use services on PDNs served by different P-GWs. In this case, the user equipment has at least one bearer path established to each P-GW 112. During handover of a user equipment from one eNodeB to another, if the S-GW 110 also changes, the bearer path from the P-GW 112 is switched to the new S-GW.

[0051] The MME 114 manages the user equipment 104 in the EPC 108 (including managing subscriber authentication, maintaining context for authenticated user equipment 104, establishing a data bearer path in the network for user traffic, and keeping track of the location of idle mobiles that have not detached from the network). For idle user equipment 104 that needs to reconnect to the access network to receive downstream data, the MME 114 initiates paging to identify the user equipment and reestablish a bearer path to and through the EUTRAN 102. The MME 114 for a particular user equipment 104 is selected by the eNodeB 106 from which the user equipment 104 initiates system access. The MME is typically part of a collection of MMEs in the EPC 108 for load sharing and redundancy purposes. In establishing a user's data bearer path, the MME 114 is responsible for selecting the P-GW 112 and S-GW 110 that constitute the ends of the data path through the EPC 108.

[0052] The PCRF 118 is responsible for policy control decision making and controlling the flow-based charging functionality in the Policy Control Activation Function ("PCEF") residing in the P-GW 110. The PCRF 118 provides QoS authorization (QoS Class Identifier ("QCI") and bitrate) that determines how a particular data flow is treated in the PCEF and ensures that this is in line with the user's subscription profile.

[0053] As previously mentioned, IP services 119 are provided by PDN 101 (shown in FIG. 1a).

[0054] 1d shows an example configuration of an eNodeB 106. The eNodeB 106 may include at least one "remote radio head" ("RRH") 132 (typically, there may be three RRHs 132) and a baseband unit ("BBU") 134. The RRHs 132 may be connected to an antenna 136. The RRHs 132 and BBU 134 may be connected using an optical interface compliant with the "common public radio interface" ("CPRI") / "enhanced CPRI" ("eCPRI") 142 specification, using an RRH-specific custom control and user plane framing method or an O-RAN Alliance-compliant control and user plane framing method. The operation of the eNodeB 106 may be characterized using the following standard parameters (and specifications): radio frequency band (Band 4, Band 9, Band 17, etc.), bandwidth (5, 10, 15, 20 MHz), access scheme (downlink: OFDMA; uplink: SC-OFDMA), antenna technology (single-user and multi-user MIMO; uplink: single-user and multi-user MIMO), number of sectors (up to 6), maximum transmission rate (downlink: 150 Mb / s; uplink: 50 Mb / s), S1 / X2 interface (1000Base-SX, 1000Base-T), and mobile environment (up to 350 km / h). The BBU 134 may be responsible for digital baseband signal processing, S1 line termination, X2 line termination, call processing, and monitoring and control processing. IP packets received from the EPC 108 (not shown in FIG. 1d) may be modulated into digital baseband signals and transmitted to the RRH 132. Conversely, digital baseband signals received from the RRH 132 may be demodulated into IP packets for transmission to the EPC 108.

[0055] The RRH 132 can transmit and receive wireless signals using an antenna 136. The RRH 132 can convert digital baseband signals from the BBU 134 to radio frequency ("RF") signals (using a converter ("CONV") 140) and can power amplify (using an amplifier ("AMP") 138) for transmission to the user equipment 104 (not shown in FIG. 1d). Conversely, RF signals received from the user equipment 104 are amplified (using AMP 138) and converted (using CONV 140) to digital baseband signals for transmission to the BBU 134.

[0056] Figure 2 shows additional details of an exemplary eNodeB 106. The eNodeB 106 includes multiple layers: "LTE Layer 1" 202, "LTE Layer 2" 204, and "LTE Layer 3" 206. LTE Layer 1 includes the physical layer ("PHY"). LTE Layer 2 includes media access control ("MAC"), radio link control ("RLC"), and packet data convergence protocol ("PDCP"). LTE Layer 3 includes various functions and protocols, including radio resource control ("RRC"), dynamic resource allocation, eNodeB measurement configuration and provisioning, radio admission control, connection mobility control, and radio resource management ("RRM"). The RLC protocol is an "automatic repeat request" ("ARQ") fragmentation protocol used over the cellular air interface. The RRC protocol handles LTE Layer 3 control plane signaling between user equipment and the EUTRAN. The RRC includes functions for connection establishment and release, system information broadcast, radio bearer establishment / reconfiguration and release, RRC connection mobility procedures, paging notification and release, and outer loop power control. The PDCP performs IP header compression and decompression, user data transfer, and sequence number maintenance for radio bearers. The BBU 134 shown in FIG. 1d may include LTE layers L1-L3.

[0057] One of the primary functions of the eNodeB 106 is radio resource management, including scheduling of both uplink and downlink air interface resources for the user equipment 104, control of bearer resources, and admission control. As an agent for the EPC 108, the eNodeB 106 is responsible for forwarding paging messages used to identify idle mobiles. The eNodeB 106 also communicates over-the-air common control channel information, header compression, encryption and decryption of over-the-air user data, and establishes handover reporting and trigger criteria. As previously mentioned, the eNodeB 106 can cooperate with other eNodeBs 106 over the X2 interface for handover and interference management purposes. The eNodeB 106 communicates with the MME of the EPC via the S1-MME interface and with the S-GW over the S1-U interface. Furthermore, the eNodeB 106 exchanges user data with the S-GW over the S1-U interface. The eNodeBs 106 and the EPC 108 have a many-to-many relationship to support load sharing and redundancy among the MMEs and S-GWs. The eNodeB 106 selects an MME from a group of MMEs so that the load can be shared by multiple MMEs to avoid congestion. II. 5G NR Wireless Communication Network

[0058] In some implementations, the current subject matter relates to 5G new radio ("NR") communication systems. 5G NR is the next communication standard after the 4G / IMT-Advanced standard. 5G networks offer higher capacity than current 4G, allowing more mobile broadband users per unit area and enabling consumption of higher and / or unlimited data volumes in gigabytes per month and per user. This may enable users to stream high-resolution media using their mobile devices much of each day (even when it is not possible to do the same with Wi-Fi networks). 5G networks have improved support for device-to-device communication, lower cost, lower latency than 4G equipment, and lower battery consumption. Such networks have data rates of tens of megabits per second for many users, data rates of 100 Mb / s for metropolitan areas, simultaneous 1 Gb / s for users in a restricted area (e.g., an office floor), many simultaneous connections for wireless sensor networks, improved spectral efficiency, improved coverage, improved signaling efficiency, and 1-10 ms latency, a reduced latency compared to existing systems.

[0059] 3 illustrates an exemplary virtual radio access network 300. The network 300 can provide communication between various components, including a base station (e.g., eNodeB, gNodeB) 301, radio equipment 303, aggregation unit 302, digital unit 304, and wireless device 306. The components in the system 300 can be communicatively coupled to the core using backhaul links 305. The aggregation unit ("CU") 302 can be communicatively coupled to the distributed unit ("DU") 304 using midhaul connections 308. The radio frequency ("RU") component 306 can be communicatively coupled to the DU 304 using fronthaul connections 310.

[0060] In some implementations, the CU 302 can provide intelligent communication capabilities to one or more DU units 304. The units 302, 304 can include one or more base stations, macro base stations, micro base stations, "remote radio heads," etc., and / or any combination thereof.

[0061] In a lower layer split architecture environment, the CPRI bandwidth requirements for NR can be several hundred Gb / s. CPRI compression can be implemented in the DU and RU (shown in Figure 3). In 5G communication systems, compressed CPRI over Ethernet frames is denoted as eCPRI and is the recommended fronthaul network. The architecture can enable standardization of fronthaul / midhaul, which can include fronthaul with higher layer split (e.g., "Option 2" or "Option 3-1" (higher / lower RLC split architecture)) and L1 split architecture ("Option 7").

[0062] In some implementations, a lower layer split architecture (e.g., "Option 7") may include receiver in the uplink, joint processing across multiple transmission points (TPs) for both DL / UL, and transport bandwidth and latency requirements for ease of deployment. Additionally, the subject lower layer split architecture may include a split between cell-level and user-level processing, which may include cell-level processing in a remote unit ("RU") and user-level processing in a DU. Additionally, using the subject lower layer split architecture, frequency-domain samples may be transported over the Ethernet fronthaul, which may be compressed to reduce fronthaul bandwidth.

[0063] 4 illustrates an example communication system 400 that can implement 5G technology and provide users with access to higher frequency bands (e.g., above 10 GHz). The system 400 can include a macrocell 402 and small cells 404, 406.

[0064] The mobile device 408 may be configured to communicate with one or more of the small cells 404, 406. The system 400 may enable separation of the control plane (C-plane) and user plane (U-plane) between the macrocell 402 and the small cells 404, 406 using different frequency bands. In particular, the small cells 404, 406 may be configured to utilize higher frequency bands when communicating with the mobile device 408. The macrocell 402 may utilize existing cellular bands for C-plane communications. The mobile device 408 may be communicatively coupled via the U-plane 412, where the small cell (e.g., the small cell 406) may provide higher data rates and more flexible, cost-effective, and energy-efficient operation. The macrocell 402 may maintain good connectivity and mobility via the C-plane 410. Furthermore, in some cases, LTE and NR may be transmitted on the same frequency.

[0065] FIG. 5a illustrates an exemplary 5G wireless communication system 500 according to some implementations of the present subject matter. The system 500 may be configured to have a lower layer split architecture according to "Option 7-2." The system 500 may include a core network 502 (e.g., 5G Core) and one or more gNodeBs (or gNBs), which may have an aggregation unit (gNB-CU). The gNB-CU may be logically separated into a control plane portion (gNB-CU-CP) 504 and one or more user plane portions (gNB-CU-UP) 506. The control plane portion 504 and the user plane portion 506 may be configured to be communicatively coupled using an E1 communication interface 514 (defined in the 3GPP standard). The control plane portion 504 may be configured to be responsible for executing the RRC and PDCP protocols of the radio stack.

[0066] The control plane and user plane portions 504, 506 of the aggregation unit of the gNB may be configured to be communicatively coupled to one or more distributed units (DUs) 508, 510 according to a higher layer split architecture. The distributed units 508, 510 may be configured to execute the upper RLC, MAC, and PHY layer protocols of the radio stack. The control plane portion 504 may be configured to be communicatively coupled to the distributed units 508, 510 using an F1-C communication interface 516, and the user plane portion 506 may be configured to be communicatively coupled to the distributed units 508, 510 using an F1-U communication interface 518. The distributed units 508, 510 may be coupled to one or more remote radio units (RUs) 512 via a fronthaul network 520 (which may include one of a switch, a link, etc.) and may communicate with one or more user equipment (not shown in FIG. 5a). The remote radio unit 512 may be configured to execute the lower portions of the PHY layer protocol and provide antenna capabilities to the remote unit for communication with user equipment (similar to the discussion above with respect to FIGS. 1a-2).

[0067] Figure 5b shows an example layer architecture 530 for a split gNB. The architecture 530, which may be configured as a virtualized and disaggregated radio access network (RAN) architecture (layers L1, L2, L3 and radio processing may be virtualized and disaggregated in the aggregation unit, distributed unit, and radio unit), may be implemented in the communication system 500 shown in Figure 5a. As shown in Figure 5b, the gNB-DU 508 may be communicatively coupled to the gNB-CU-CP control plane portion 504 (also shown in Figure 5a) and the gNB-CU-UP user plane portion 506. Each of the components 504, 506, 508 may be configured to include one or more layers.

[0068] The gNB-DU 508 may include RLC, MAC, and PHY layers, as well as various communication sublayers. These may include an F1 application protocol (F1-AP) sublayer, a GPRS Tunneling Protocol (GTPU) sublayer, a Stream Control Transmission Protocol (SCTP) sublayer, a User Datagram Protocol (UDP) sublayer, and an Internet Protocol (IP) sublayer. As previously described, the distribution unit 508 may be communicatively coupled to the control plane portion 504 of the aggregation unit, which may include the F1-AP, SCTP, and IP sublayers, and the Radio Resource Control and PDCP Control (PDCP-C) sublayers. Furthermore, the distribution unit 508 may be communicatively coupled to the user plane portion 506 of the aggregation unit of the gNB. The user plane portion 506 may include the Service Data Adaptation Protocol (SDAP), PDCP User (PDCP-U), GTPU, UDP, and IP sublayers.

[0069] Figure 5c shows an example functional split in the gNB architecture shown in Figures 5a-b. As shown in Figure 5c, the gNB-DU 508 may be communicatively coupled to the gNB-CU-CP 504 and the GNB-CU-UP 506 using an F1-C communication interface. The gNB-CU-CP 504 and the GNB-CU-UP 506 may be communicatively coupled using an E1 communication interface. A higher portion of the PHY layer (or Layer 1) may be performed by the gNB-DU 508, and a lower portion of the PHY layer may be performed by the RU (not shown in Figure 5c). As shown in Figure 5c, the RRC and PDCP-C portions may be performed by the control plane portion 504, and the SDAP and PDCP-U portions may be performed by the user plane portion 506.

[0070] Some of the functions of the PHY layer in a 5G communication network may include error detection on transport channels and suggestion to higher layers, FEC encoding / decoding of transport channels, hybrid ARQ soft combining, rate matching of coded transport channels to physical channels, mapping of coded transport channels onto physical channels, power weighting of physical channels, modulation and demodulation of physical channels, frequency and time synchronization, radio characteristic measurements and suggestion to higher layers, MIMO antenna processing, digital and analog beamforming, RF processing, and other functions.

[0071] The MAC sublayer of Layer 2 may perform beam management, random access procedures, mapping between logical channels and transport channels, concatenation of multiple MAC service data units (SDUs) belonging to one logical channel into transport blocks (TBs), multiplexing / demultiplexing of SDUs belonging to logical channels to / from TBs delivered on transport channels to / from the physical layer, scheduling of reporting information, error correction via HARQ, priority handling between logical channels for one UE, priority handling between UEs via dynamic scheduling, transport format selection, and other functions. The RLC sublayer's functions may include forwarding upper layer packet data units (PDUs), error correction via ARQ, reordering of data PDUs, duplication and protocol error detection, reestablishment, etc. The PDCP sublayer may be responsible for forwarding user data, various functions during reestablishment procedures, retransmission of SDUs, discarding SDUs in the uplink, forwarding of control plane data, and others.

[0072] The RRC sublayer of Layer 3 may perform functions such as broadcasting system information to the NAS and AS, establishing, maintaining and releasing RRC connections, security, establishing, configuring, maintaining and releasing point-to-point radio bearers, mobility functions, reporting, and other functions. III. Dealing with core network connectivity failures

[0073] In some implementations of the present subject matter, an F1 interface can be set up between a CU (e.g., a gNB-CU, e.g., in FIG. 5a) of a base station (e.g., a gNodeB, e.g., in FIG. 5a) of a 5G wireless communication system (e.g., system 500, e.g., in FIG. 5a) and a DU (e.g., DUs 508, 510, e.g., in FIGS. 5a-5c) of the base station, even if the base station does not have connectivity to a core network (e.g., 5GC 502, e.g., in FIG. 5a) of the 5G wireless communication system. Currently, under the 3GPP standard, if the base station does not have connectivity to the core network, a UE cannot set up a connection with the 5G wireless communication system. Therefore, the DU cannot provide services to UEs that rely on a base station connected to the 5G core network to communicate over the wireless communication system. Thus, at least for those UEs (e.g., non-standby (NSA) UEs), the DU is underutilized. However, setting up an F1 interface despite a core network connection failure allows the DU to transition to an active state, allowing the DU to provide services to those UEs (e.g., non-standby (NSA) UEs).

[0074] According to current 3GPP standards, setting up an F1 interface between a gNB-DU and a gNB-CU involves the DU sending an F1 setup request to the CU, and the CU then sending an F1 setup response to the DU. The CU then sends a GNB-DU configuration update message to the DU, including various configuration data. Here, if the base station-5G core network connection is down, the CU sends a GNB-CU configuration update message to the DU, including forbidden list information or excluding available public land mobile network (PLMN) list information.

[0075] In some implementations of the present subject matter, the CU is configured to send a GNB-CU Configuration Update message to the DU regardless of whether the base station has connectivity to the 5G core network. In this way, even if the base station does not currently have connectivity to the 5G core network, the F1 interface can be set up and the DU can transition to an active state, allowing the DU to provide service to a subset of UEs (e.g., NSA UEs) that do not depend on a base station connected to the 5G core network in order for the UE to communicate over the wireless communication system.

[0076] As specified by 3GPP, the GNB-CU Configuration Update message sent from the CU to the DU includes a List of Cells to be Activated information element (IE) and a List of Cells to be Barred IE. The List of Cells to be Activated IE suggests to the DU which cells to activate (if not already activated) to enable communication. The List of Cells to be Barred IE suggests to the DU which cells communication should be barred from and whether to cause the cells to stop System Information Block Type 1 (SIB1) transmission or allow the cells to transmit SIB1 without a 5G System (5GS) Tracking Area Code (TAC). Alternatively or additionally, omitting the Available PLMN List IE from the message can be used to suggest to the DU whether to cause the cells to stop SIB1 transmission or allow SIB1 transmission without a 5G System (5GS) Tracking Area Code (TAC).

[0077] In some implementations of the current subject matter, when an F1 interface is set up with a base station that has connectivity to a core network, a GNB-CU Configuration Update message can be utilized as defined by 3GPP. When an F1 interface is set up during connectivity down between the base station and the core network, the List of Cells to be Activated IE in the gNB-CU Configuration Update message can indicate to the DU that the gNodeB can provide support for NSA UEs, and the List of Cells to be Forbidden IE in the gNB-CU Configuration Update message can indicate to the DU that the gNodeB cannot provide support for SA UEs. In this way, existing elements defined by 3GPP, such as the GNB-CU CONFIGURATION UPDATE message, the Cells to be Activated List IE, and the Cells to be Barred List IE, are utilized in setting up the F1 interface when 5G core network connectivity is down, allowing the base station to provide service to NSA UEs even when connectivity between the base station and the 5G core network is down.

[0078] FIG. 6 illustrates an example method 600 for addressing a core network connectivity failure according to some implementations of the present subject matter. The method 600 includes a DU (e.g., DUs 508, 510, e.g., in FIGS. 5a-5c) of a base station (e.g., a gNB, e.g., in FIG. 5a) requesting 602 an F1 interface setup from a CU (e.g., a gNB-CU, e.g., in FIG. 5a). The CU transmits 604 a response to the DU. The response transmitted 604 to the DU indicates to the DU whether to start transmitting system information block (SIB) information. The SIB information transmitted by the base station (e.g., its DU) according to 3GPP standards carries information (e.g., 5GS TAC) necessary for a SA UE to access a cell.

[0079] In some implementations, asking (602) may include the DU sending an F1 setup request to the CU in accordance with 3GPP standards. In response to the F1 setup request, the CU may send an F1 setup response to the DU in accordance with 3GPP standards (604). Also in response to the F1 setup request, the CU may send a GNB-CU configuration update to the DU in accordance with 3GPP standards (604). The GNB-CU configuration update message may include a list of cells to be activated and a list of cells to be barred IEs in accordance with 3GPP standards. Receipt by the DU of the list of cells to be activated and the list of cells to be barred IEs indicates to the DU that SIB information should not be transmitted or that SIBs should be transmitted without 5GS TAC (e.g., because access for SA UEs should be barred). Alternatively or additionally, excluding the Available PLMN List IE from the GNB-CU Configuration Update message can be used to suggest to the DU whether to stop the cell from transmitting SIB1 or allow the cell to transmit SIB1 without a 5GS TAC. Thus, as described above, existing elements defined by 3GPP, such as the GNB-CU Configuration Update message, the Cells to be Activated List IE, the Cells to be Barred List IE, and / or the Available PLMN List, can be used to set up the F1 interface when core network connectivity is down, enabling the base station to provide service to NSA UEs even when connectivity between the base station and the 5G core network is down.

[0080] In method 600, if the base station does not have core connectivity, the DU changes the cell state to active (606) and transmits SIB information as suggested to the DU by the Cells to be Activated List IE sent from the CU to the DU and the Cells to be Barred List IE that is not sent by the CU at all and not received by the DU (or, in some implementations, by the Cells to be Barred List IE that is sent empty from the CU to the DU). Alternatively or additionally, including an Available PLMN List IE in the message can be used to suggest to the DU whether to start SIB transmission with 5GS TAC. When the cell state is active and the SIB information is transmitted, the NSA UE and SA UE can access the base station (e.g., the DU).

[0081] If the base station does not have core connectivity, as suggested to the DU by the Barred Cell List IE, the DU changes its cell state to Active (608) but does not transmit SIB information. Thus, NSA UEs can access the base station (e.g., the DU) due to the Active state, but SA UEs cannot access the base station due to the lack of SIB information from the base station (e.g., the DU). When core connectivity is later restored (or established as an initial connection), the DU transmits SIB information with the 5GS TAC (610), and SA UEs can access the base station (e.g., the UE) in addition to the NSA UEs that were previously allowed access.

[0082] In some implementations, upon restoration of core connectivity (or establishment as an initial connection), the CU sends a second GNB-CU Configuration Update to the DU in accordance with 3GPP standards, similar to the previously sent GNB-CU Configuration Update message described above. In this way, the DU is informed that core connectivity exists, and SIB information with the 5GS TAC may be sent (610) to allow access for SA UEs in addition to the NSA UEs that were previously allowed access.

[0083] 7a and 7b illustrate an example implementation of the method 600 of FIG. 6 with respect to an example system 700 configured to address core network connectivity failures according to some implementations of the present subject matter. The system 700 of FIGS. 7a and 7b is a 5G system. As such, the system 700 includes a gNB-DU 702 (labeled “DU” in FIGS. 7a and 7b) (e.g., DUs 508, 510, such as in FIGS. 5a-5c), a gNB-CU (e.g., gNB-CU, such as in FIG. 5a), and a 5GC 706 (e.g., 5GC 502, such as in FIG. 5a). Figures 7a and 7b also illustrate a control plane portion of the gNB-CU, a gNB-CU-CP 704 (labeled “CUCP” in FIGS. 7a and 7b). The control plane portion gNB-CU-CP704 is configured to detect core network connectivity status (e.g., up or down) and can send and receive various messages in the F1 setup according to the 3GPP standards.

[0084] Generally, Figure 7a illustrates an implementation in which F1 setup is initiated due to 5GC connectivity down (708), such as when the gNB does not have connectivity to the 5GC (706), and Figure 7b illustrates an implementation in which F1 setup is initiated due to 5GC connectivity up (710), such as when the gNB has connectivity to the 5GC (706).

[0085] As shown in Figure 7a, the F1 setup procedure may begin with 5GC connectivity down (708) between a gNB (e.g., its CUCP 704) and a 5GC 706. The CUCP 704 is aware of the 5G connectivity status according to 3GPP standards and knows that 5GC connectivity is down (708).

[0086] Upon 5GC connectivity down (708), the DU 702 sends an F1 setup request to the CUCP 704 according to the 3GPP standard (712). As shown in FIG. 7a, the F1 setup request may include a 5G system (5GS) tracking area code (TAC) IE.

[0087] In response to receiving the F1 setup request, the CUCP 704 sends an F1 setup response to the DU 702 (714) in accordance with the 3GPP standard. In accordance with the 3GPP standard, the F1 setup response may optionally include a list of cells to be activated. As shown in Figure 7a, the F1 setup response sent (714) is empty and does not include a list of cells to be activated.

[0088] The CUCP 704 then sends (716) a GNB-CU Configuration Update message to the DU 702. In response to receiving the GNB-CU Configuration Update message, the DU 702 sends (718) a GNB-CU Configuration Update Confirm message to the CU 704 in accordance with the 3GPP standard.

[0089] The GNB-CU Configuration Update message is sent 716 to the DU 702 according to the 3GPP standard and may include a List of Cells to be Activated IE and a List of Cells to be Barred IE, as shown in FIG. 7a.

[0090] The List of Cells to be Activated IE indicates, in accordance with 3GPP standards, which cells should be activated (if not already activated) to enable communication. Receipt of a non-empty List of Cells to be Activated IE indicates to the DU 702 that the DU 702 can transition the cell to an active state (720) (e.g., the cell state can be set to active). A DU 702 in the active state can be communicatively coupled to and provide service to one or more NSA UEs even if core connectivity is down (708).

[0091] Receipt by DU702 of the List of Barred Cells IE suggests to DU702 that System Information Block Type 1 (SIB1) should not be scheduled or that SIB1 should be scheduled without a 5GS TAC. SIB1, transmitted by the gNB according to 3GPP standards, carries information necessary for an SA UE to access the cell. Thus, not scheduling SIB1 or scheduling SIB1 without a 5GS TAC may prevent the SA UE from accessing the cell and may prevent DU702 from providing service to the SA UE (after which time, DU702 may later provide service to the SA UE if 5G core network connectivity is up, as discussed herein).

[0092] After transitioning the cell state to active (720), the DU 702, in accordance with the 3GPP standard, sends a GNB-DU configuration update message to the CUCP 704 (722). As shown in Figure 7a, the GNB-DU configuration update message reports a service status to the CUCP 704 that indicates that the cell is in service.

[0093] In response to receiving the GNB-DU Configuration Update message, the CUCP 704 sends a GNB-DU Configuration Update Confirm message to the DU 702 (724) in accordance with the 3GPP standard.

[0094] 5GC connectivity may remain down 708 for any period of time after CUCP 704 sends the GNB-DU Configuration Update Confirm message 724. During this time, DU 702 may provide service to one or more NSA UEs, but not to SAs.

[0095] At some point after the CUCP 704 sends the GNB-DU Configuration Update Confirm message (724), 5GC connectivity between the gNB (e.g., its CUCP 704) and the 5GC 706 may be up (726). The CUCP 704 is aware of the 5G connectivity status according to 3GPP standards and knows that 5GC connectivity is up (726).

[0096] In response to 5GC connectivity being up (726) after previously being down (708), the CUCP 704 sends (728) a second GNB-CU configuration update message to the DU 702 in accordance with 3GPP standards. In response to receiving the second GNB-CU configuration update message, the DU 702 sends (730) a second GNB-CU configuration update confirm message to the CU 704 in accordance with 3GPP standards.

[0097] The Cells to be Activated List IE (and, in some implementations, an empty Cells to be Barred List IE) included in the second GNB-CU Configuration Update message reflects that gNB-5GC connectivity is up (726) by including the cells that were in the Cells to be Barred List IE sent in the previous GNB-CU Configuration Update message (716) in the Cells to be Activated List IE. Thus, receipt by the DU of the Cells to be Activated List IE in the second GNB-CU Configuration Update Confirm message indicates to the DU 702 that it can start SIB1 scheduling with 5GS TAC (732) and that SA UEs can access the cells. Alternatively or additionally, the inclusion of an Available PLMN List IE can be used to indicate to the DU to start SIB1 transmission with 5GS TAC (732). Therefore, the DU702 can provide service to both NSA UEs and SA UEs when 5GC connectivity is up (726).

[0098] As shown in Figure 7b, the F1 setup procedure may begin with 5GC connectivity up (710) between a gNB (e.g., its CUCP 704) and a 5GC 706. The CUCP 704 is aware of the 5G connectivity status according to 3GPP standards and knows that 5GC connectivity is up (710).

[0099] The F1 setup procedure of Figure 7b is performed in accordance with the 3GPP standard and includes the DU 702 sending an F1 setup request to the CUCP 704 (740), followed by the CUCP 704 sending an F1 setup response to the DU 702 (742) and sending a GNB-CU configuration update message to the DU 702 (744). In response to receiving the GNB-CU configuration update message, the DU 702 sends a GNB-CU configuration update confirm message to the CU 704 (746) in accordance with the 3GPP standard.

[0100] The GNB-CU Configuration Update message sent to the DU 702 (744) according to the 3GPP standard may include a List of Cells to be Activated IE and a List of Cells to be Barred IE, as shown in FIG. 7b. In some implementations, there are no cells to be barred, so the List of Cells to be Barred IE is omitted from the GNB-CU Configuration Update message. Unlike the F1 setup procedure of FIG. 7a, SA UEs do not need to be barred because 5GC connectivity is up (710). Receipt of a non-empty List of Cells to be Activated IE indicates to the DU 702 that the DU 702 may transition the cell to an active state (748) (e.g., the cell state may be set to active). After transitioning the cell state to active (748), the DU 702 sends a GNB-DU Configuration Update message to the CUCP 704 (750). In response to receiving the GNB-CU Configuration Update message, the DU 702 can send a GNB-CU Configuration Update Confirm message to the CU 704 (752) and initiate SIB1 scheduling (754), allowing SA UEs to access the cell. Thus, the DU 702 can serve both NSA UEs and SA UEs when 5GC connectivity is up (710).

[0101] Although Figures 7a and 7b are described with respect to a 5G wireless communication system, addressing core network connectivity failures as described herein may similarly be performed with respect to other types of wireless communication systems, such as wireless communication systems of generations beyond 5G.

[0102] In some implementations, the present subject matter may be configured to be implemented in a system 800, as shown in FIG. 8. The system 800 may include one or more of a processor 810, a memory 820, a storage device 830, and an input / output device 840. Each of the components 810, 820, 830, and 840 may be interconnected using a system bus 850. The processor 810 may be configured to process instructions for execution within the system 600. In some implementations, the processor 810 may be a single-threaded processor. In alternative implementations, the processor 810 may be a multi-threaded processor. The processor 810 may further be configured to process instructions stored in the memory 820 or the storage device 830, including receiving or transmitting information through the input / output device 840. The memory 820 may store information within the system 800. In some implementations, the memory 820 may be a computer-readable medium. In alternative implementations, the memory 820 may be a volatile memory unit. Further, in some implementations, memory 820 may be a non-volatile memory unit. Storage device 830 may provide mass storage for system 800. In some implementations, storage device 830 may be a computer-readable medium. In alternative implementations, storage device 830 may be a floppy disk device, a hard disk device, an optical disk device, a tape device, a non-volatile solid-state memory, or any other type of storage device. Input / output device 840 may be configured to provide input / output operations for system 800. In some implementations, input / output device 840 may include a keyboard and / or a pointing device. In alternative implementations, input / output device 840 may include a display unit for displaying a graphical user interface.

[0103] 8 illustrates an example method 900 for handling core network connectivity failures in accordance with some implementations of the present subject matter. Method 900 may be performed, for example, using the implementations shown and described with respect to FIGS. 7a and 7b.

[0104] The method 900 may include transitioning (902) a gNodeB to an active state upon a connection down between the gNodeB (e.g., the gNodeB of FIG. 5a, the gNodeB of FIGS. 7a and 7b, etc.) and a 5G core network (e.g., 5GC 502 of FIG. 5a, 5GC 706 of FIGS. 7a and 7b, etc.) such that the gNodeB can provide support to NSA UEs upon a connection down between the gNodeB and the 5G core network.

[0105] In some implementations, the current subject may include one or more of the following optional features:

[0106] In some implementations, transitioning a gNodeB to an active state may include the active state being set in a DU of the gNodeB (e.g., DUs 508, 510 in Figures 5a-5c, DU 602 in Figures 6a and 6b, etc.) in response to information received by the DU from a CU of the gNodeB (e.g., gNB-CU in Figure 5a, gNB-CU in Figures 6a and 6b, etc.).

[0107] In some implementations, transitioning the gNodeB to the active state may include setting up an F1 interface between a CU of the gNodeB (e.g., gNB-CU in FIG. 5a, gNB-CU in FIGS. 6a and 6b, etc.) and a DU of the gNodeB (e.g., DUs 508 and 510 in FIGS. 5a-5c, DU 602 in FIGS. 6a and 6b, etc.). Further, the F1 interface may be set up between the CU of the gNodeB and the DU of the gNodeB without performing SIB1 scheduling, or the F1 interface may be set up between the CU of the gNodeB and the DU of the gNodeB by performing SIB1 without a 5G system (5GS) Tracking Area Code (TAC).

[0108] In some implementations, transitioning a gNodeB to the active state may include sending a GNB-CU Configuration Update message from the gNodeB's CU (e.g., the gNB-CU in FIG. 5a, the gNB-CU in FIGS. 6a and 6b, etc.) to the gNodeB's DU (e.g., DUs 508 and 510 in FIGS. 5a-5c, DU 602 in FIGS. 6a and 6b, etc.). Furthermore, the list of cells to be activated included in the GNB-CU Configuration Update message can indicate to the DU that the gNodeB can provide support for NSA UEs, and including a list of cells to be forbidden in the GNB-CU Configuration Update message or excluding the available PLMN list from the GNB-CU Configuration Update message can indicate to the DU that the gNodeB cannot provide support for standalone (SA) UEs.

[0109] In some implementations, the operations may further include, upon connection down between the gNodeB and the 5G core network, transitioning the gNodeB to an active state, and then enabling the gNodeB to provide support to the SA UE upon connection between the gNodeB and the 5G core network becoming available. Further, transitioning the gNodeB to an active state so that the gNodeB can provide support for the NSA UE may include sending a first GNB CU Configuration Update message from the gNodeB's CU (e.g., the gNB-CU in Figure 5a, the gNB-CU in Figures 6a and 6b, etc.) to the gNodeB's DU (e.g., DUs 508, 510 in Figures 5a to 5c, DU 602 in Figures 6a and 6b, etc.), and enabling the gNodeB to provide support for the SA UE may include sending a second GNB CU Configuration Update message from the gNodeB's CU to the gNodeB's DU, and / or the gNodeB may be transitioned to an active state without performing SIB1 scheduling or performing SIB1 scheduling without 5GS TAC when the connection between the gNodeB and the 5G core network is down, and transitioning the gNodeB to an active state so that the gNodeB can provide support for the SA UE may include performing SIB1 scheduling. Furthermore, the first list of cells to be activated included in the first GNB-CU configuration update message can indicate to the DU that the gNodeB can provide support for NSA UEs, the first list of cells to be prohibited included in the first GNB-CU configuration update message or the available PLMN list excluded from the first GNB-CU configuration update message can indicate to the DU that the gNodeB cannot provide support for SA UEs, and the second list of cells to be activated and / or the available PLMN list included in the second GNB-CU configuration update message can indicate to the DU that the gNodeB can provide support for SA UEs.

[0110] In some implementations, a gNodeB may include at least one processor and at least one non-transitory storage medium.

[0111] The systems and methods disclosed herein may be embodied in various forms, including, for example, a data processor such as a computer including a database, digital electronic circuitry, firmware, software, or any combination thereof. Furthermore, the above-described features and other aspects and principles of the disclosed implementations may be implemented in various environments. Such environments and associated applications may be specially configured to perform the various processes and operations of the disclosed implementations, or they may include general-purpose computers or computing platforms selectively activated or reconfigured by code to provide the required functionality. The processes disclosed herein are not inherently related to any particular computer, network, architecture, environment, or other apparatus, but may be implemented by any suitable combination of hardware, software, and / or firmware. For example, various general-purpose devices may be used with programs written in accordance with the teachings of the disclosed implementations, or it may be more convenient to configure specialized devices or systems to perform the required methods and techniques.

[0112] The systems and methods disclosed herein may be implemented as a computer program product (i.e., a computer program tangibly embodied in an information carrier (e.g., a machine-readable storage device or a propagated signal) for execution by or to control the operation of a data processing apparatus (e.g., a programmable processor, computer, or multi-computer)). The computer program may be written in any form of programming language, including compiled or interpreted languages, and may be deployed in any form, including a stand-alone program or a module, component, subroutine, or other unit suitable for use in a computing environment. The computer program may be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communications network.

[0113] As used herein, the term "user" may refer to any entity, including a person or a computer.

[0114] Although ordinal numbers such as first, second, etc. may refer to an order in some circumstances, ordinal numbers used in this document do not necessarily imply an order. For example, ordinal numbers may be used simply to distinguish one item from another. For example, distinguishing a first event from a second event does not necessarily imply a chronological order or a fixed reference system (just as the first event in one paragraph of a description may be different from the first event in another paragraph of the description).

[0115] The above description is intended to be illustrative, but not limiting, of the scope of the invention, which is defined by the appended claims. Other implementations are within the scope of the following claims.

[0116] These computer programs, software, software applications, applications, components, or codes, which may also be referred to as programs, include machine instructions for a programmable processor and may be implemented in a high-level procedural and / or object-oriented programming language and / or assembly / machine language. As used herein, the term "machine-readable medium" refers to any computer program product, apparatus, and / or device (e.g., magnetic disks, optical disks, memory, and programmable logic devices (PLDs)) used to provide machine instructions and / or data to a programmable processor, including a machine-readable medium that receives machine instructions as a machine-readable signal. The term "machine-readable signal" refers to any signal used to provide machine instructions and / or data to a programmable processor. A machine-readable medium may non-transitory store such machine instructions (e.g., non-transitory solid-state memory or a magnetic hard drive or any equivalent storage medium). Alternatively or additionally, a machine-readable medium may store such machine instructions in a transitory manner (e.g., processor cache or other random access memory associated with one or more physical processor cores).

[0117] To provide for user interaction, the subject matter described herein may be implemented on a computer having a display device, such as a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user, and a keyboard and pointing device, such as a mouse or trackball, through which the user can provide input to the computer. Other types of devices may also be used to provide for user interaction. For example, feedback provided to the user may be any form of sensory feedback, such as visual feedback, auditory feedback, or tactile feedback. Input from the user may be received in any form, including, but not limited to, acoustic, speech, or tactile input.

[0118] The subject matter described herein may be implemented in a computing system that includes back-end components such as one or more data servers, or middleware components such as one or more application servers, or front-end components such as one or more client computers having a graphical user interface or web browser through which a user can interact with an implementation of the subject matter described herein, or any combination of such back-end, middleware, or front-end components. The components of the system may be interconnected by any form or medium of digital data communication, such as a communications network. Examples of communications networks include, but are not limited to, a local area network ("LAN"), a wide area network ("WAN"), and the Internet.

[0119] A computing system may include clients and servers. Clients and servers are generally, but not limited to, remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

[0120] The implementations presented in the foregoing description do not represent all implementations consistent with the subject matter described herein. Rather, they are merely some examples consistent with aspects related to the described subject matter. While a few variations have been described in detail above, other modifications or additions are possible. In particular, additional features and / or variations may be provided in addition to those presented herein. For example, the implementations described above may be directed to various combinations and subcombinations of the disclosed features and / or combinations and subcombinations of some additional features disclosed above. In addition, the logic flow depicted in the accompanying figures and / or described herein does not necessarily require the particular order depicted or sequential order to achieve desirable results. Other implementations may also be within the scope of the following claims.

Claims

1. at least one processor; When executed by the at least one processor, transitioning the gNodeB to an active state upon a connection down between the gNodeB and a 5G core network, such that the gNodeB can provide support for non-standalone (NSA) user equipment (UE) upon the connection down between the gNodeB and the 5G core network; at least one non-transitory storage medium storing instructions that cause the at least one processor to perform operations comprising: An apparatus comprising:

2. 2. The apparatus of claim 1, wherein transitioning the gNodeB to the active state comprises: the active state being set in a distributed unit (DU) of the gNodeB in response to information received by the distributed unit (DU) of the gNodeB from a central aggregation unit (CU) of the gNodeB.

3. The apparatus of claim 1 , wherein transitioning the gNodeB to the active state comprises setting up an F1 interface between an aggregation unit (CU) of the gNodeB and a distribution unit (DU) of the gNodeB.

4. 4. The apparatus of claim 3, wherein the F1 interface is set up between the CU of the gNodeB and the DU of the gNodeB without performing System Information Block Type 1 (SIB1) scheduling, or the F1 interface is set up between the CU of the gNodeB and the DU of the gNodeB by performing SIB1 without a 5G system (5GS) Tracking Area Code (TAC).

5. 2. The apparatus of claim 1, wherein transitioning the gNodeB to the active state comprises sending a GNB-CU configuration update message from a aggregation unit (CU) of the gNodeB to a distributed unit (DU) of the gNodeB.

6. The list of cells to be activated included in the GNB-CU Configuration Update message indicates to the DU that the gNodeB can provide support for NSA UEs; Including a list of cells to be forbidden in the GNB-CU Configuration Update message or excluding an available PLMN list from the GNB-CU Configuration Update message indicates to the DU that the gNodeB cannot provide support for standalone (SA) UEs.

6. The apparatus of claim 5.

7. The operation After transitioning the gNodeB to the active state when the connection between the gNodeB and the 5G core network is down, enabling the gNodeB to provide support to a standalone (SA) UE in response to the connection between the gNodeB and the 5G core network becoming available; The apparatus of claim 1 further comprising:

8. Transitioning the gNodeB to the active state so that the gNodeB can provide support for NSA UEs comprises sending a first GNB CU configuration update message from an aggregation unit (CU) of the gNodeB to a distributed unit (DU) of the gNodeB; Enabling the gNodeB to provide support for SA UEs comprises sending a second GNB CU configuration update message from the CU of the gNodeB to the DU of the gNodeB.

8. The apparatus of claim 7.

9. The first list of cells to be activated included in the first GNB-CU Configuration Update message indicates to the DU that the gNodeB can provide support for NSA UEs; The first list of cells to be forbidden included in the first GNB-CU configuration update message or the available PLMN list excluded from the first GNB-CU configuration update message indicates to the DU that the gNodeB cannot provide support for SA UEs; The second list of cells to be activated and / or the available PLMN list included in the second GNB-CU configuration update message indicate to the DU that the gNodeB can provide support for the SA UE; 9. The apparatus of claim 8.

10. The gNodeB is transitioned to the active state without performing system information block type 1 (SIB1) scheduling when the connection between the gNodeB and the 5G core network goes down, or the gNodeB is transitioned to the active state by performing SIB1 scheduling without 5GS TAC when the connection between the gNodeB and the 5G core network goes down; transitioning the gNodeB to the active state so that the gNodeB can provide support for SA UEs comprises performing SIB1 scheduling.

8. The apparatus of claim 7.

11. The apparatus of claim 1 , wherein the gNodeB includes the at least one processor and the at least one non-transitory storage medium.

12. 1. A computer-implemented method comprising: transitioning a gNodeB to an active state upon a connection down between the gNodeB and a 5G core network, such that the gNodeB can provide support for non-standalone (NSA) user equipment (UE) upon the connection down between the gNodeB and the 5G core network.

13. 13. The method of claim 12, wherein transitioning the gNodeB to the active state comprises: the active state being set in a distributed unit (DU) of the gNodeB in response to information received by the distributed unit (DU) of the gNodeB from a central aggregation unit (CU) of the gNodeB.

14. The method of claim 12 , wherein transitioning the gNodeB to the active state comprises setting up an F1 interface between an aggregation unit (CU) of the gNodeB and a distribution unit (DU) of the gNodeB.

15. 13. The method of claim 12, wherein transitioning the gNodeB to the active state comprises sending a GNB-CU configuration update message from a aggregation unit (CU) of the gNodeB to a distributed unit (DU) of the gNodeB.

16. When executed by at least one processor, transitioning the gNodeB to an active state upon a connection down between the gNodeB and a 5G core network, such that the gNodeB can provide support for non-standalone (NSA) user equipment (UE) upon the connection down between the gNodeB and the 5G core network; and at least one non-transitory storage medium storing instructions that cause the at least one processor to perform operations comprising:

17. 17. The storage medium of claim 16, wherein transitioning the gNodeB to the active state comprises that the active state is set in the distribution unit (DU) of the gNodeB in response to information received by the distribution unit (DU) of the gNodeB from an aggregation unit (CU) of the gNodeB.

18. 17. The storage medium of claim 16, wherein transitioning the gNodeB to the active state comprises setting up an F1 interface between an aggregation unit (CU) of the gNodeB and a distribution unit (DU) of the gNodeB.

19. 17. The storage medium of claim 16, wherein transitioning the gNodeB to the active state comprises sending a GNB-CU configuration update message from an aggregation unit (CU) of the gNodeB to a distribution unit (DU) of the gNodeB.

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