Anchor cell failure handling for on-demand SIB1

Abstract

An apparatus including at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: detect a failure of an anchor cell; and transmit, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

Description

Anchor Cell Failure Handling For On-Demand SIB1TECHNICAL FIELD

[0001] The examples and non-limiting example embodiments relate generally to communications and, more particularly, to anchor cell failure handling for on-demand SIB1.BACKGROUND

[0002] It is known for a communication device to gain access to a communication network with an access network node.SUMMARY

[0003] In accordance with an aspect, an apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: detect a failure of an anchor cell; and transmit, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

[0004] In accordance with an aspect, an apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and determine an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

[0005] In accordance with an aspect, an apparatus includes at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; andreceive, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The foregoing aspects and other features are explained in the following description, taken in connection with the accompanying drawings.

[0007] FIG. 1 is a block diagram of one possible and non-limiting system in which the example embodiments may be practiced.

[0008] FIG. 2 shows an example configuration update signaling exchange between a gNB- DU and a gNB-CU.

[0009] FIG. 3 shows an example configuration update signaling exchange between NG- RAN nodei and NG-RAN node?.

[0010] FIG. 4 shows different scenarios discussed in RANI and RAN2.

[0011] FIG. 5 shows options considered for an OD-SIB1 functional architecture.

[0012] FIG. 6 shows an overall solution call flow showing method #1.

[0013] FIG. 7 shows an overall solution call flow showing method #2.

[0014] FIG. 8 shows an overall solution call flow showing method #3.

[0015] FIG. 9 is an example apparatus configured to implement the examples described herein.

[0016] FIG. 10 shows a representation of an example of non-volatile memory media used to store instructions that implement the examples described herein.

[0017] FIG. 11 is an example method, based on the examples described herein.

[0018] FIG. 12 is an example method, based on the examples described herein.

[0019] FIG. 13 is an example method, based on the examples described herein.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0020] Turning to FIG. 1, this figure shows a block diagram of one possible and non-limiting example in which the examples may be practiced. A user equipment (UE) 110, radio access network (RAN) node 170, and network element(s) 190 are illustrated. In the example of FIG.1, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device that can access the wireless network 100. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123. The UE 110 includes a module 140, comprising one of or both parts 140-1 and / or 140-2, which may be implemented in a number of ways. The module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120. The module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured to, with the one or more processors 120, cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

[0021] The RAN node 170 in this example is a base station that provides access for wireless devices such as the UE 110 to the wireless network 100. The RAN node 170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the RAN node 170 may be a NG-RAN node, which is defined as either a gNB or an ng-eNB. A gNB is a node providing NR user plane and control plane protocol terminations towards the UE, and connected via the NG interface (such as connection 131) to a 5GC (such as, for example, the network element(s) 190). The ng-eNB is a node providing E-UTRA user plane and controlplane protocol terminations towards the UE, and connected via the NG interface (such as connection 131) to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a central unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which DU 195 is shown. Note that the DU 195 may include or be coupled to and control a radio unit (RU). The gNB-CU 196 is a logical node hosting radio resource control (RRC), SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that control the operation of one or more gNB-DUs. The gNB-CU 196 terminates the Fl interface connected with the gNB-DU 195. The Fl interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU 195 is a logical node hosting RLC, MAC and PHY layers of the gNB or en-gNB, and its operation is partly controlled by gNB-CU 196. One gNB-CU 196 supports one or multiple cells. One cell may be supported with one gNB-DU 195, or one cell may be supported / shared with multiple DUs under RAN sharing. The gNB-DU 195 terminates the Fl interface 198 connected with the gNB-CU 196. Note that the DU 195 is considered to include the transceiver 160, e.g., as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, e.g., under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station or node.

[0022] The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N / W I / F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, one or more memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory / memories and processor(s), and / or other hardware, but these are not shown.

[0023] The RAN node 170 includes a module 150, comprising one of or both parts 150-1 and / or 150-2, which may be implemented in a number of ways. The module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152. The module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module150 may be implemented as module 150-2, which is implemented as computer program code 153 and is executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured to, with the one or more processors 152, cause the RAN node 170 to perform one or more of the operations as described herein. Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

[0024] The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

[0025] The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH / DU 195, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a central unit (CU), gNB-CU 196) of the RAN node 170 to the RRH / DU 195. Reference 198 also indicates those suitable network link(s).

[0026] A RAN node / gNB can comprise one or more TRPs to which the methods described herein may be applied. FIG. 1 shows that the RAN node 170 comprises TRP 51 and TRP 52, in addition to the TRP represented by transceiver 160. Similar to transceiver 160, TRP 51 and TRP 52 may each include a transmitter and a receiver. The RAN node 170 may host or comprise other TRPs not shown in FIG. 1.

[0027] It is noted that the description herein indicates that “cells” perform functions, but it should be clear that equipment which forms the cell may perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360 degree area so that the single base station’s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a singlecarrier and a base station may use multiple carriers. So if there are three 120 degree cells per carrier and two carriers, then the base station has a total of 6 cells.

[0028] The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and / or a data communications network (e.g., the Internet). Such core network functionality for 5G may include location management functions (LMF(s)) and / or access and mobility management function(s) (AMF(S)) and / or user plane functions (UPF(s)) and / or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (mobility management entity) / SGW (serving gateway) functionality. Such core network functionality may include SON (self- organizing / optimizing network) functionality. These are merely example functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to the network element 190. The link 131 may be implemented as, e.g., an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N / W I / F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. Computer program code 173 may include SON and / or MRO functionality 172.

[0029] The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, or a virtual network. Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

[0030] The computer readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memorydevices and systems, optical memory devices and systems, non-transitory memory, transitory memory, fixed memory and removable memory. The computer readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as nonlimiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, network element(s) 190, and other functions as described herein.

[0031] In general, the various example embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback devices having wireless communication capabilities, internet appliances including those permitting wireless internet access and browsing, tablets with wireless communication capabilities, head mounted displays such as those that implement virtual / augmented / mixed reality, as well as portable units or terminals that incorporate combinations of such functions. The UE 110 can also be a vehicle such as a car, or a UE mounted in a vehicle, a UAV such as e.g. a drone, or a UE mounted in a UAV. The user equipment 110 may be a terminal device, such as mobile phone, mobile device, sensor device etc., the terminal device being a device used by the user or not used by the user.

[0032] UE 110, RAN node 170, and / or network element(s) 190, (and associated memories, computer program code and modules) may be configured to implement (e.g. in part) the methods described herein. Thus, computer program code 123, module 140-1, module 140-2, and other elements / features shown in FIG. 1 of UE 110 may implement user equipment related aspects of the examples described herein. Similarly, computer program code 153, module 150-1, module 150-2, and other elements / features shown in FIG. 1 of RAN node 170 may implement gNB / TRP related aspects of the examples described herein. Computer program code 173 and other elements / features shown in FIG. 1 of network element(s) 190 may be configured to implement network element related aspects of the examples described herein.

[0033] Having thus introduced a suitable but non-limiting technical context for the practice of the example embodiments, the example embodiments are now described with greater specificity.

[0034] An anchor cell refers to a cell transmitting SIB1 as legacy procedure (up to 3 GPP Rel. 18). UE shall be able to detect and camp to anchor cell. An anchor cell may provide assistance information of NES cell(s), e.g., on how to trigger the request for the SIB1 of the NES cell. An NES cell refers to a cell that may transmit SIB1 as a legacy procedure or may not transmit SIB1. If the NES cell does not transmit SIB1 as part of the legacy procedure, the SIB1 can be on-demand requested based on UL signal transmitted by the UE. Further in this description, the term legacy SIB1 operation is used to designate the mode of operation where the NES cell transmits SIB1 as part of the legacy procedure (up to 3GPP Rel. 18). Either of the terms OD-SIB1 operation or On-Demand SIB1 mode are used for the mode of operation where SIB1 of the NES cell is requested by the UE. In this description, a NES cell supports on-demand SIB1 and legacy SIB1 operations. The anchor and NES cells could be in the same gNB or in different gNBs. gNB (NES) refers to a gNB hosting the NES cell. gNB (Anchor) refers to a gNB hosting the anchor cell. NES refers to Network Energy Savings, OD-SIB1 refers to On-Demand SIB1, and WUS refers to Uplink Wake Up Signal for OD-SIB1. In this description, the terms WUS and UL-WUS are used interchangeably.

[0035] Based on the outcome of RAN# 102 meeting, one of objectives (Objective-2) agreed in the WID (RP -234065) is related to the support of On-Demand SIB1 for UEs in Idle / Inactive states - the objective statement is as below:

[0036] The On-Demand SIB1 functionality calls for 2 types of cells - an Anchor Cell (orCell-A) and a NES Cell. The definition of these types of cells is given in section 2.

[0037] The main functions of the Anchor Cell are receiving the WUS configuration and SIB1 Info from the NES Cell, sending WUS configuration to the UE, receiving the UL-WUS from the UE, and broadcasting the OD-SIB1. The actual functions are dependent upon the solution option chosen in 3GPP.

[0038] Cell Failure Handling in RAN3 includes Fl support and Xn support. Referring to FIG. 2, for Fl support, the Served Cells To Delete Item IE is contained in the GNB-DU CONFIGURATION UPDATE 210 - if this IE is present, then the gNB-CU (Anchor) 196 shall delete information of the cell indicated by an Old NR CGI IE. As shown in FIG. 2, the gNB-DU 195 transmits the GNB-DU CONFIGURATION UPDATE message 210 to the gNB-CU 196. gNB-CU 196 transmits the GNB-DU CONFIGURATION UPDATE ACKNOWLEDGE message 220 to the gNB-DU 195.

[0039] Referring to FIG. 3, for Xn support, the Served Cells NR To Delete IE is contained in the NG-RAN NODE CONFIGURATION UPDATE 310 - the gNB 170-1 with Anchor Cell could send this to the gNB 170-2 with the NES Cell. Then the gNB-CU (NES) shall delete the information of cell indicated by the Old NR CGI IE. As shown in FIG. 3, the NG-RAN nodei 170-1 transmits the NG-RAN NODE CONFIGURATION UPDATE message 310 to the NG-RAN node2170-2. NG-RAN node2170-2 transmits the NG-RAN NODE CONFIGURATION UPDATE ACKNOWLEDGE message 320 to NG-RAN nodei 170-1.

[0040] In the above defined procedures defined, there is no cause value present in the Configuration Update Request messages and it is assumed that the target side just removes the referred cells.

[0041] FIG. 4 shows different case scenarios. In the four scenarios shown (401, 403, 405, 407), Cell A access node 402 provides access to Cell A 404, and NES Cell access node 406 provides access to NES cell 408.

[0042] Scenario la (RANI Case 2) 401 shows a non-standalone case, where Cell A access node 402 transmits UL WUS configuration in SIB 410 to UE 110, UE 110 transmits UL WUS 412 to NES Cell access node 406, and NES Cell access node 406 transmits SIB1 414 to UE 110.

[0043] Scenario lb (RANI Case 3: SIB1 424 from Cell A 404) 403 shows a non-standalone case, where Cell A access node 402 transmits UL WUS configuration in SIB 420 to UE 110, UE 110 transmits UL WUS 422 to Cell A access node 402, Cell A access node 402 transmits SIB1 424 to UE 110.

[0044] Scenario 2405 shows a non-standalone case, where Cell A access node 402 transmits UL WUS configuration in RRC release (430) to UE 110, UE 110 transmits UL WUS 432 to NES cell access node 406, and NES Cell access node 406 transmits SIB1 434 to UE 110.

[0045] Scenario 3 (RANI Case 1) 407 shows a standalone case, where NES Cell access node 406 transmits UL WUS configuration 440 to UE 110, UE 110 transmits UL WUS 442 to NES cell access node 406, and NES cell access node 406 transmits SIB1 444 to UE 110.

[0046] RANI #117 agreed about the following cases:

[0047] RAN2 #126 have the following agreements:

[0048] Based on the above agreements, RANI and RAN2 are considering non-standalone scenarios and relying on the fact that one Cell A or multiple Cell A are considered as anchor cells for enabling OD-SIB1 operation by NES cell.

[0049] Considered with the examples described herein is the energy saving on-demand SIB 1 operation at a NES cell with the support of the anchor cell. Note that in the future, further network energy saving operations could be assisted by the anchor cell. The anchor cell provides means for a given UE to access the NES cell when it goes into On-Demand SIB 1 mode. In this sense, the anchor cell plays a very critical role in supporting this NES functionality, and therefore if the anchor cell experiences some type of failure or outage there needs to be some means to determine whether the NES cells shall continue in NES state or should exit the NES state and additionally means for informing the NES cell about actions they are required to perform.

[0050] FIG. 5 shows an OD-SIB1 functional architecture, including options considered for Rel-19. FIG. 5 shows Case 2 501 that includes Option 1 message 512, Option B message 510, and Option X message 514, and Case 3 503 that includes Option 2 message 516, Option B message 510, and Option Y message 518. In Case 2 501, Cell A 404 transmits UL WUS configuration 510 to UE 110, UE 110 transmits UL WUS (PRACH) 512 to NES Cell 408, and NES Cell 408 transmits OD-SIB1 514 to UE 110. In Case 3 503, Cell A 404 transmits WUS configuration 510 to UE 110, UE 110 transmits WUS 516 to Cell A 404, and Cell A 404 transmits OD-SIB1 518 to UE 110. Thus, FIG. 5 shows a simplified network architecture for supporting on-demand SIB1 (OD-SIB1).

[0051] Accordingly, the examples described herein address the scenario where the anchor cell (e.g. Cell A 404 or Cell A 170-A shown in FIG. 6, FIG. 7, and FIG. 8) provides at least one user equipment (e.g. UE 110 or a plurality of user equipments (UEs)) assistance for at least one network energy savings cell.

[0052] The assistance provided to the at least one user equipment by the anchor cell may comprise an uplink signal configuration that the at least one user equipment uses to transmit a signal to request system information for the at least one network energy savings cell. The anchor cell may receive, from the at least one user equipment with the signal, the request for the system information for the at least one network energy savings cell. The anchor cell may transmit, to the at least one user equipment, the system information for the at least one networkenergy savings cell.

[0053] The assistance provided to the at least one user equipment by the anchor cell may comprise system information for the at least one network energy savings cell. The system information for the at least one network energy savings cell may be provided by the anchor cell to the at least one user equipment with an on-demand system information block 1.

[0054] The Cell A (Anchor Cell) (e.g. Cell A 404 or Cell A 170-A shown in FIG. 6, FIG. 7, and FIG. 8) and the NES Cell (e.g. NES Cell 408 or Cell NES 170-N shown in FIG. 6, FIG. 7, and FIG. 8) are the main roles attributed to NR cells. The examples described herein address the scenario where the cell A and the NES cell are served by different NG-RAN nodes, however other scenarios are also covered by the examples described herein, such as when the cell A and the NES cell are served by the same access node (such as an NG-RAN node).

[0055] The main functions of the Anchor Cell (i.e. Cell A) for supporting OD-SIB1 operations of a NES cell are the following (1-4): 1) Receiving the WUS configuration (case 2) or SIB 1 Info (case 3) from the NES Cell over network interfaces (Xn or NG as applicable). In case of split architecture of NG-RAN node serving the cell A and / or the NES cell, also potentially transfer this information over Fl; 2) Sending WUS configuration to the UE, e.g. via system information broadcast; 3) Receiving the UL-WUS from the UE; 4) Send the OD- SIB1 of the NES cell to the UE (case 3), e.g. via system information broadcast, or send an indication over network interfaces (Xn or NG) to the NES cell to broadcast SIB1 (case 2). The actual functions may be based on the solution option chosen by 3 GPP.

[0056] Given these functions, there would be multiple consequences in case of an Anchor Cell Failure while the NES cell is operating in OD-SIB1 mode with the support of the Anchor Cell. Based on the time of failure, the impact could be one or more of: Unable to send WUS configuration to the UE, and / or Unable to receive or handle the UL-WUS transmitted by the UE, and / or Unable to broadcast the OD-SIB1.

[0057] In summary, such a failure in the cell A / anchor cell could impair UEs from receiving the SIB1 of the NES cell, and the NES cell becomes inaccessible as a result of the Anchor Cell failure. As can be readily observed, this would be a catastrophic situation for the affected UEs since they in the scenario of a single cell A has no means of accessing the network. And hence, such a failure scenario has to be addressed in 3GPP.

[0058] Not addressing these type of failures could lead to operators having to adopt higher network reliability risks and consequently leading to lower network energy savings.

[0059] Described herein are methods and signaling to handle an anchor cell failure when a NES cell is operating in on-demand SIB1 (OD-SIB1) mode with the support of that anchor cell. The herein described aspects are below:

[0060] Method#l : Anchor Cell / gNB reports its failure to NES Cell / gNB and during the failure can be configured to operate with a new restricted mode (preventing new UEs access) but still broadcasting the WUS configuration (impact on Fl / Xn). Method#l includes a) and b) below:

[0061] a) The gNB-CU (Anchor) sends an anchor cell failure indication to the gNB-CU (NES) including information related to whether the transmi ssion(s) related to the OD-SIB1 can be continued or not by the anchor cell. The examples described herein extend Fl / Xn signaling of cell failure (see prior description related to signaling for cell failure) including new information about the failure type and, particularly, indicating whether the DL broadcast channel of the anchor is still working or not. In one example, the indication indicates that the anchor cell operates in restricted mode (preventing new UEs access) but that still broadcasting the WUS configuration. In one example, the anchor cell that was configured to transmit both the WUS configuration and NES Cell’s SIB1 indicates that due to failure it can transmit only the WUS configuration (but not any longer the SIB1). In this case, it requests the NES Cell / gNB to provide a WUS configuration valid for (to be used on) the NES cell. Before the failure, the Cell A was configured to broadcast both its own WUS configuration and OD- SIB1. After the failure, the Cell A indicates that it can broadcast only the WUS configuration and not the OD-SIB1. In order to improve the chances of UE acquiring OD-SIB1, the anchor cell may start broadcasting the WUS configuration of the NES Cell. This may allow the UE to send WUS to the NES cell and thereby acquire the OD-SIB1 from there.

[0062] b) Based on the received information the gNB-CU (NES) decides taken into account the deployment whether to (the exact decision is up to network implementation). Option#l: Configure a different Anchor for the NES cell - if feasible based on the deployment, or Option#2: Switch the NES cell back to regular SIB1, or Option#3: Configure the failing anchor cell to still broadcast WUS configuration if failure type does not affect DL broadcast of the cell (e.g. transport failure, only UL failure, etc.), including i-iii: i) In one example, ifconfigured to still broadcast the WUS config, the anchor cell could operate with indicating cell barring (i.e. to prevent new UE accesses) + indicating ‘anchor cell broadcast information’ related to OD-SIB1; ii) Those indications can be provided in MIB and / or SIB1; iii) In one example, the anchor cell that was configured to transmit both the WUS configuration and NES Cell’s SIB1 is configured to transmit only the WUS configuration - based on the capability to support UL transmissions. In this case, it provides a WUS configuration valid for (to be used on) the NES cell to be broadcasted by the Anchor Cell during failure.

[0063] Method#2: Anchor Cell / gNB reports unavailability to continue OD-SIB1 anchor role due to cell failure to NES Cell / gNB and requests the NES Cell / gNB to reactivate regular SIB1 mode (impact on Fl / Xn). Method#2 includes a) and b) below:

[0064] a) Described herein is a new Fl / Xn signaling related to OD-SIB1 to indicate unavailability to continue OD-SIB1 anchor role due to cell failure. In one example, the anchor gNB / CU sends a reactivation request of NES cell’s regular SIB1 mode to the NES cell (i.e. indication of stopped OD-SIB1 anchor role) with a cause ‘cell failure’.

[0065] b) Based on that, gNB-CU (NES) can decide whether to (the exact decision is up to network implementation): Option#l : configure a different Anchor for the NES cell - if feasible or Option#2: switch NES cell back to regular SIB1. The anchor cell’s restricted mode of operation described above can also be combined with this method.

[0066] Method#3 : NW infrastructure implementation. Method# 3 includes a) and b) below:

[0067] a) The NG-RAN node serving the cell A / anchor cell indicates to CU (Anchor) / CU (NES) that the cell A / anchor cell has been removed from the set of cells using existing Fl / Xn signaling. For deployments without Xn, new NG signaling is described herein for this indication.

[0068] b) gNB-CU (NES) decides whether to (the exact decision is up to network implementation): Option#l : switch NES cell back to regular SIB1 transmission, or Option#2: configure a different Anchor for the NES cell - if feasible

[0069] The solution option-3 in Method- 1 (i.e. restricted options) has RAN2 impacts on the gNB (Anchor) too - such as for UE procedures for anchor cell failure.

[0070] Accordingly, the solution focuses on the RAN3 aspects, including actions of the NES gNB when the Anchor gNB goes into the restrictive mode. RAN2 aspects may also be considered, including actions of the Anchor gNB and UE impacts when the anchor goes into the restrictive mode

[0071] Method-1: Anchor Cell Failure with DL BCH Working

[0072] FIG. 6 shows the overall solution call flow showing Method#l. FIG. 6 shows a signaling exchange between anchor gNB Anchor Cell-B (170-B), including gNB-DU-B (195- B) and gNB-CU-B (196-B), anchor gNB Anchor Cell-A (170-A), including gNB-DU-A (195- A) and gNB-CU-A (196-A), and NES gNB NES Cell (170-N), including gNB-CU-NES 196- N and gNB-DU-NES (195-N). The step description of Method#l is as follows.

[0073] Steps 1-6: Successful activation of OD-SIB1 Mode in gNB[NES]

[0074] The gNB (NES) chooses the Anchor cell in gNB-Anchor-A - shares the WUS Configuration and OD-SIB1 information. When the gNB (NES) chooses to activate OD-SIB1 mode in the NES Cell, it indicates the same to the gNB Anchor A. gNB Anchor A then broadcasts the WUS Configuration over gNB Anchor Cell and handles any UL-WUS Request by broadcasting the OD-SIB1 information. The UE may then read the OD-SIB1 information to access the NES Cell.

[0075] Steps 7-9: Anchor Cell Failure

[0076] The Anchor Cell A fails. The following are some examples of the cell failure foreseen (1-3):

[0077] 1) The anchor cell may have intermittent transport failures and it may miss out on updated state of the NES cells or updates on the NES cells SIB1. In this scenario it may be best to wake up the NES cell associated with the anchor cell. This would also improve enduser experience (e.g. accessibility). Note: Depending on which interface the transport failure is on, the anchor cell may not be able to communicate with the NES CU, hence CU should also be able to trigger the detection of this failure.

[0078] 2) If the type of failure reported is a high RACH error rate then the solution adopted could be periodic broadcast of the SIB1 OD, since anyways in this case the anchor cell iswould not be constrained in terms of available capacity / resources

[0079] 3) Unplanned hardware or software issue in the cell leading to cell going off air

[0080] The solution option below is chosen by the gNB (NES) based on the failure cause / category of failure that is shared by the gNB (Anchor) over Fl / Xn in a new IE “Failure Type”. This IE could take the following values (1-2): 1) DL BCH Working - this indicates that the anchor cell could still support broadcasting the WUS configuration as part of its DL broadcast and hence, could work in the restricted mode, 2) Cell Failure - this indicates a general failure of the anchor cell that impacts all UL and DL functions of the cell.

[0081] This IE is to be part of the IE Served Cells To Modify Item. In a deployment where a single anchor cell / gNB is mapped to multiple NES cells / gNBs, the failure indication in step 9 is sent by the gNB (Anchor) to all its mapped gNB (NES)s over Xn. In case there is a transport failure on Xn, then the failure could come through 0AM interface. Method# 1 considers the case where the Failure Type value = DL BCH Working (609).

[0082] Steps 10-14: Solution Option-1 (610)

[0083] In case the error is a temporary one which could keep the anchor working in the restricted mode, there may not be a need for identifying another anchor gNB. This is an implementation decision at the NES gNB / cell.

[0084] If the Failure Type indicates DL BCH Working (609), the gNB (NES) could still identify a different gNB that could host the anchor cell (step 10) and indicates the WUS configuration and OD-SIB1 information (step 13) and OD-SIB1 activation to that gNB (step 14).

[0085] The identification could be done by any of the following methods: select any gNB with an Xn link with the gNB (NES) which has a cell that is a neighboring cell of the failed Anchor cell, or select based on historic mobility patterns between the NES cell and other cells, i.e., incoming and outgoing HOs.

[0086] Select all gNBs in the same tracking area. The gNB (Anchor) Cell B now starts acting as the anchor cell supporting the NES cell.

[0087] Such a choice is made when the failure cause indicates that the Anchor Cell A cannotplay the role of anchor anymore and the gNB (NES) is able to identify an alternate anchor cell / gNB to play that role.

[0088] Steps 15-17: Solution Option-2 (620)

[0089] If the Failure Type indicates DL BCH Working (619), the gNB (NES) could simply choose to disable the OD-SIB1 mode in its NES cell (step 15) and disable the WUS / OD-SIB1 transmission in the Anchor cell (step 16.1). The NES cell returns to normal / periodic SIB1 broadcast.

[0090] Step 18: Solution Option-3 (630)

[0091] If the failure cause indicates that the Anchor Cell A can continue to play the role of anchor (i.e. Failure Type = DL BCH Working (629)), then the gNB (NES) just lets the cell continue playing that role (step 18). This is typically in the case where the failure is not expected to be permanent and where the operations could continue. For example, there could be a case, where although the gNB of Cell A has detected a failure in its operations it determines that it can continue to provide the assistance information (WUS configuration / OD-SIB1 of NES cell) to UEs for NES Cells, in some cases via modified operation. The gNB (NES) could then provide an updated WUS configuration (step 19.1) that the gNB (Anchor) could start broadcasting.

[0092] The gNB of Cell A could, for example, determine that based on RACH issues it detects to periodically transmit the WUS / Config / SIBl OD of its associated NES Cells with these needing to be requested via a RACH procedure from the UE. In another embodiment the gNB of Cell A could determine to increase the transmissions frequency (lower periodicity) of the WUS / OD-SIB1 NES, e.g., if they were already being transmitted without explicit request from UEs via RACH.

[0093] In this case, the gNB (NES) could optionally request the gNB-Anchor A to continue with the OD-SIB1 operation (step 19.1).

[0094] In FIG. 6, at 601, gNB-CU-NES 196-N and gNB-DU-NES 195-N are in normal SIB1 mode. At step 1, gNB-DU-NES 195-N transmits to gNB-CU-NES 196-N a message over an Fl interface that includes a WUS configuration of the NES Cell and SIB1 information. At step 2, the gNB-CU-NES 196-N and gNB-CU-A 196-A have a message exchanged over anXn interface, where the message includes a Cell ID, the WUS configuration of the NES cell, and SIB1 information. At step 3, the gNB-CU-NES 196-N activates OD-SIB1 mode in the NES cell. At step 4, the gNB-CU-NES 196-N transmits to the gNB-CU-A 196-A an OD SIB1 activation request over an Xn interface that includes a cell ID and activation information. At step 5, the gNB-CU-A 196-A performs a WUS configuration Broadcast. At step 6, the gNB- CU-A 196-A handles any UL-WUS and broadcasts OD-SIB1. At step 7, the gNB-DU-A 195- A detects anchor cell failure of Cell-A.

[0095] In FIG. 6, Option 1 610 includes item 609, and steps 10, 11.1, 11.2, 12, 13, 14, and items 613 and 615. Option 2 620 includes item 619 and steps 15, 16.1, 16.2, and 17. Option 3 630 includes item 629, and steps 18, 19.1, and 19.2.

[0096] As shown in FIG. 6, step 8 includes gNB-DU-A 195-A transmitting a gNB-DU Config Update (Served Cells to Modify Item - Failure Type) over an Fl interface to gNB- CU-A 196-A. At Step 9, gNB-CU-A 196-A transmits an NG-RAN Config Update (Served Cells To Modify Item - Failure Type) to gNB-CU-NES 196-N over an Xn interface. At 609, as part of option 1 610, the gNB-CU-NES 196-N determines that the Failure Type is DL BCH Working. At step 10, the gNB-CU-NES 196-N identifies gNB-B 170-B to be a backup Anchor Cell. At step 11.1, gNB-CU-NES 196-N transmits an OD SIB1 deactivation request with a Cell ID over an Xn interface to gNB-CU-A 196-A. At step 11.2, gNB-CU-A 196-A transmits an OD SIB1 deactivation request with a cell ID over an Fl interface to gNB-DU-A 195-A. At step 12, gNB-DU-A 195-A and gNB-CU-A 196-A determine to stop WUS Config / OD-SIBl broadcast. At step 13, gNB-CU-NES 196-N transmits a message over an Xn interface to gNB- CU-B 196-B that includes a cell ID, the WUS configuration of NES cell, and SIB1 info. At step 14, gNB-CU-NES 196-N transmits an OD SIB1 activation request over an Xn interface to gNB-CU-B 196-B that includes a cell ID and activation, and gNB-CU-B 196-B and gNB- DU-B 195-B perform a WUS configuration Broadcast (at 613) and handle any UL-WUS and broadcast OD-SIB1 (at 615).

[0097] At 619, as part of option 2 620, gNB-CU-NES 196-N determines that the failure type is DL BCH working. At step 15, the gNB-CU-NES 196-N decides to disable OD-SIB1. At step 16.1, gNB-CU-NES 196-N transmits an OD SIB1 deactivation request with a cell ID over an Xn interface to gNB-CU-A 196-A. At step 16.2, gNB-CU-A 196-A transmits an OD SIB1 deactivation request with a Cell ID over an Fl interface to gNB-DU-A 195-A. At step 17,gNB-CU-A 196-A and gNB-DU-A 195-A stop WUS configuration and OD-SIBl broadcast.

[0098] At 629, as part of Option 3 630, gNB-CU-NES 196-N determines that the failure type is DL BCH Working. At step 18, gNB-CU-NES 196-N decides to let anchor cell A continue in restricted mode and broadcast WUS config. At step 19.1 gNB-CU-NES 196-N transmits an OD SIB1 activation request over an Xn interface to gNB-CU-A 196-A that includes a Cell ID, an indication to continue with OD-SIBl, and an updated WUS config. At step 19.2, gNB-CU-A 196-A transmits an OD SIB1 activation request over an Fl interface to gNB-DU-A 195-A that includes a Cell ID, an indication to continue with OD-SIBl, and an updated WUS config.

[0099] Method-2: Anchor Cell Failure with Cell Failure.

[0100] FIG. 7 shows the overall solution call flow showing Method#2. FIG. 7 shows a signaling exchange between anchor gNB Anchor Cell-B (170-B), including gNB-DU-B (195- B) and gNB-CU-B (196-B), anchor gNB Anchor Cell-A (170-A), including gNB-DU-A (195- A) and gNB-CU-A (196-A), and NES gNB NES Cell (170-N), including gNB-CU-NES 196- N and gNB-DU-NES (195-N). The step description of Method#2 is as follows.

[0101] Method#2 considers the case where the Failure Type value = Cell Failure. It is to be noted that this scenario is different from the cell removal and covers those cases where the cell failure impacts largely OD-SIBl functionality (both UL and DL), but is different from removal of cells. In this case too, the failure is indicated through the IE Served Cells To Modify Item with the Failure Type = Cell Failure (step 9). Refer also to items 711 and 721. The solution option 1 (610) and option 2 (620) given in Method# 1 are applicable to Method#2 and have been shown accordingly in FIG. 7 as option 1 (710) and option 2 (720).

[0102] In FIG. 7, at 701, gNB-CU-NES 196-N and gNB-DU-NES 195-N are in normal SIB1 mode. At step 1, gNB-DU-NES 195-N transmits to gNB-CU-NES 196-N a message over an Fl interface that includes a WUS configuration of the NES Cell and SIB1 information. At step 2, the gNB-CU-NES 196-N and gNB-CU-A 196-A have a message exchanged over an Xn interface, where the message includes a Cell ID, the WUS configuration of the NES cell, and SIB1 information. At step 3, the gNB-CU-NES 196-N activates OD-SIBl mode in the NES cell. At step 4, the gNB-CU-NES 196-N transmits to the gNB-CU-A 196-A an OD SIB1 activation request over an Xn interface that includes a cell ID and activation information. Atstep 5, the gNB-CU-A 196-A performs a WUS configuration Broadcast. At step 6, the gNB- CU-A 196-A handles any UL-WUS and broadcasts OD-SIB1. At step 7, the gNB-DU-A 195- A detects anchor cell failure of Cell-A.

[0103] In FIG. 7, Option 1 710 includes item 711, and steps 10, 11.1, 11.2, 12, 13, 14, and items 713 and 715. Option 2 720 includes item 721 and steps 15, 16.1, 16.2, and 17.

[0104] As shown in FIG. 7, step 8 includes gNB-DU-A 195-A transmitting a gNB-DU Config Update (Served Cells to Modify Item - Failure Type) over an Fl interface to gNB- CU-A 196-A. At Step 9, gNB-CU-A 196-A transmits an NG-RAN Config Update (Served Cells To Modify Item - Failure Type) to gNB-CU-NES 196-N over an Xn interface. At 711, as part of option 1 710, the gNB-CU-NES 196-N determines that the Failure Type is Cell Failure. At step 10, the gNB-CU-NES 196-N identifies gNB-B 170-B to be a backup Anchor Cell. At step 11.1, gNB-CU-NES 196-N transmits an OD SIB1 deactivation request with a Cell ID over an Xn interface to gNB-CU-A 196-A. At step 11.2, gNB-CU-A 196-A transmits an OD SIB1 deactivation request with a cell ID over an Fl interface to gNB-DU-A 195-A. At step 12, gNB-DU-A 195-A and gNB-CU-A 196-A determine to stop WUS Config / OD-SIBl broadcast. At step 13, gNB-CU-NES 196-N transmits a message over an Xn interface to gNB- CU-B 196-B that includes a cell ID, the WUS configuration of NES cell, and SIB1 info. At step 14, gNB-CU-NES 196-N transmits an OD SIB1 activation request over an Xn interface to gNB-CU-B 196-B that includes a cell ID and activation, and gNB-CU-B 196-B and gNB- DU-B 195-B perform a WUS configuration Broadcast (at 713) and handle any UL-WUS and broadcast OD-SIB1 (at 715).

[0105] At 721, as part of option 2 720, gNB-CU-NES 196-N determines that the failure type is Cell Failure. At step 15, the gNB-CU-NES 196-N decides to disable OD-SIB1. At step 16.1, gNB-CU-NES 196-N transmits an OD SIB1 deactivation request with a cell ID over an Xn interface to gNB-CU-A 196-A. At step 16.2, gNB-CU-A 196-A transmits an OD SIB1 deactivation request with a Cell ID over an Fl interface to gNB-DU-A 195-A. At step 17, gNB-CU-A 196-A and gNB-DU-A 195-A stop WUS configuration and OD-SIB1 broadcast.

[0106] Method-3: Anchor Cell Removal Implementation

[0107] FIG. 8 shows the overall solution call flow showing Method#3. FIG. 8 shows a signaling exchange between anchor gNB Anchor Cell-B (170-B), including gNB-DU-B (195-B) and gNB-CU-B (196-B), anchor gNB Anchor Cell-A (170-A), including gNB-DU-A (195- A) and gNB-CU-A (196-A), and NES gNB NES Cell (170-N), including gNB-CU-NES 196- N and gNB-DU-NES (195-N). The step description of Method#3 is as follows.

[0108] Method#3 considers the case where the Anchor cell is deleted and is communicated using existing Fl / Xn signaling (i.e. Using the IE Served Cells To Delete Item in step 9. In this case, the gNB (NES) could decide to opt for either of the 2 solution options given, i.e. allocate another gNB as the anchor and let the NES cell operate in OD-SIB1 mode (or) exit the OD-SIB1 mode in the NES cell. This is implementation behavior of the gNB (NES) described herein.

[0109] The solution option 1 (610) and option 2 (620) given in Method# 1 are applicable to Method#3 and have been shown accordingly as option 1 (810) and option 2 (820) in FIG. 8.

[0110] In FIG. 8, at 801, gNB-CU-NES 196-N and gNB-DU-NES 195-N are in normal SIB1 mode. At step 1, gNB-DU-NES 195-N transmits to gNB-CU-NES 196-N a message over an Fl interface that includes a WUS configuration of the NES Cell and SIB1 information. At step 2, the gNB-CU-NES 196-N and gNB-CU-A 196-A have a message exchanged over an Xn interface, where the message includes a Cell ID, the WUS configuration of the NES cell, and SIB1 information. At step 3, the gNB-CU-NES 196-N activates OD-SIB1 mode in the NES cell. At step 4, the gNB-CU-NES 196-N transmits to the gNB-CU-A 196-A an OD SIB1 activation request over an Xn interface that includes a cell ID and activation information. At step 5, the gNB-CU-A 196-A performs a WUS configuration Broadcast. At step 6, the gNB- CU-A 196-A handles any UL-WUS and broadcasts OD-SIB1. At step 7, the gNB-DU-A 195- A detects anchor cell failure of Cell-A.

[0111] In FIG. 8, Option 1 810 includes steps 10, 11.1, 11.2, 12, 13, 14, and items 813 and 815. Option 2 820 includes steps 15, 16.1, 16.2, and 17.

[0112] As shown in FIG. 8, step 8 includes gNB-DU-A 195-A transmitting a gNB-DU Config Update (Served Cells to Delete Item) over an Fl interface to gNB-CU-A 196-A. At Step 9, gNB-CU-A 196-A transmits an NG-RAN Config Update (Served Cells To Delete Item) to gNB-CU-NES 196-N over an Xn interface. At step 10, as part of Option 1 810, the gNB-CU-NES 196-N identifies gNB-B 170-B to be a backup Anchor Cell. At step 11.1, gNB- CU-NES 196-N transmits an OD SIB1 deactivation request with Cell IDs of other anchor cellsover an Xn interface to gNB-CU-A 196-A. At step 11.2, gNB-CU-A 196-A transmits an OD SIB1 deactivation request with cell IDs over an Fl interface to gNB-DU-A 195-A. At step 12, gNB-DU-A 195-A and gNB-CU-A 196-A determine to stop WUS Config / OD-SIBl broadcast. At step 13, gNB-CU-NES 196-N transmits a message over an Xn interface to gNB- CU-B 196-B that includes a cell ID, the WUS configuration of NES cell, and SIB1 info. At step 14, gNB-CU-NES 196-N transmits an OD SIB1 activation request over an Xn interface to gNB-CU-B 196-B that includes a cell ID and activation, and gNB-CU-B 196-B and gNB- DU-B 195-B perform a WUS configuration Broadcast (at 813) and handle any UL-WUS and broadcast OD-SIB1 (at 815).

[0113] At step 15, as part of Option 2 820, the gNB-CU-NES 196-N decides to disable OD- SIB1. At step 16.1, gNB-CU-NES 196-N transmits an OD SIB1 deactivation request with a cell IDs of other anchor cells over an Xn interface to gNB-CU-A 196-A. At step 16.2, gNB- CU-A 196-A transmits an OD SIB1 deactivation request with Cell IDs over an Fl interface to gNB-DU-A 195-A. At step 17, gNB-CU-A 196-A and gNB-DU-A 195-A stop WUS configuration and OD-SIB 1 broadcast.

[0114] In steps 11.1 and 16.1 in FIG. 8, the following should be noted. There is no need to send deactivation of OD-SIB 1 on the Anchor cell that has been deleted. However, there could be an optional need to deactivate OD-SIB 1 on any other Anchor cells in that gNB. This could be for the following reasons: When OD-SIB 1 mode is deactivated in the NES cell, it should be notified to all the associated Anchor cells, and if the NES gNB decides to associate with a different Anchor gNB, then again it may send deactivation on all the Anchor cells (not the one that has been deleted) in that Anchor gNB.

[0115] The above methods could be applicable to the case where the NES cell and Anchor cell are located in different gNB-DUs in the same gNB as well - in this case, the common gNB-CU effects the above signaling over Fl with no Xn signaling involved. In case where the NES and Anchor cells are co-located in a single gNB-DU, there is no RAN3 signaling involved - with the gNB-DU managing the failure locally / internally. In deployments where Xn link is not present between the gNB (Anchor) and gNB (NES), the Xn signaling could be replaced with NG signaling with the IES similar to the ones given in the solution description.

[0116] Accordingly, the ideas described herein thus relate to changes in Xn and / or Fl interfaces.

[0117] FIG. 9 is an example apparatus 900, which may be implemented in hardware, configured to implement the examples described herein. The apparatus 900 comprises at least one processor 902 (e.g. an FPGA and / or CPU), one or more memories 904 including computer program code 905, the computer program code 905 having instructions to carry out the methods described herein, wherein the at least one memory 904 and the computer program code 905 are configured to, with the at least one processor 902, cause the apparatus 900 to implement circuitry, a process, component, module, or function (implemented with control module 906) to implement the examples described herein. The one or more memories 904 may include a non-transitory memory, a transitory memory, a volatile memory (e.g. RAM), or a non-volatile memory (e.g. ROM).

[0118] Failure / deletion handling 930 implements the examples described herein related to anchor cell failure / deletion handling for on-demand SIB1.

[0119] The apparatus 900 includes a display and / or VO interface 908, which includes user interface (UI) circuitry and elements, that may be used to display aspects or a status of the methods described herein (e.g., as one of the methods is being performed or at a subsequent time), or to receive input from a user such as with using a keypad, camera, touchscreen, touch area, microphone, biometric recognition, one or more sensors, etc. The apparatus 900 includes one or more communication e.g. network (N / W) interfaces (I / F(s)) 910. The communication I / F(s) 910 may be wired and / or wireless and communicate over the Internet / other network(s) via any communication technique including via one or more links 924. The link(s) 924 may be the link(s) 131 and / or 176 from FIG. 1. The link(s) 131 and / or 176 from FIG. 1 may also be implemented using transceiver(s) 916 and corresponding wireless link(s) 926. The communication I / F(s) 910 may comprise one or more transmitters or one or more receivers.

[0120] The transceiver 916 comprises one or more transmitters 918 and one or more receivers 920. The transceiver 916 and / or communication I / F(s) 910 may comprise standard well-known components such as an amplifier, filter, frequency-converter, (de)modulator, and encoder / decoder circuitries and one or more antennas, such as antennas 914 used for communication over wireless link 926.

[0121] The control module 906 of the apparatus 900 comprises one of or both parts 906-1 and / or 906-2, which may be implemented in a number of ways. The control module 906 may be implemented in hardware as control module 906-1, such as being implemented as part ofthe one or more processors 902. The control module 906-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the control module 906 may be implemented as control module 906-2, which is implemented as computer program code (having corresponding instructions) 905 and is executed by the one or more processors 902. For instance, the one or more memories 904 store instructions that, when executed by the one or more processors 902, cause the apparatus 900 to perform one or more of the operations as described herein. Furthermore, the one or more processors 902, the one or more memories 904, and example algorithms (e.g., as flowcharts and / or signaling diagrams), encoded as instructions, programs, or code, are means for causing performance of the operations described herein.

[0122] The apparatus 900 to implement the functionality of control 906 may be UE 110, RAN node 170 (e.g. gNB), or network element(s) 190 (e.g. LMF 190). Thus, processor 902 may correspond to processor(s) 120, processor(s) 152 and / or processor(s) 175, memory 904 may correspond to one or more memories 125, one or more memories 155 and / or one or more memories 171, computer program code 905 may correspond to computer program code 123, computer program code 153, and / or computer program code 173, control module 906 may correspond to module 140-1, module 140-2, module 150-1, and / or module 150-2, and communication I / F(s) 910 and / or transceiver 916 may correspond to transceiver 130, antenna(s) 128, transceiver 160, antenna(s) 158, N / W I / F(s) 161, and / or N / W I / F(s) 180. Alternatively, apparatus 900 and its elements may not correspond to either of UE 110, RAN node 170, or network element(s) 190 and their respective elements, as apparatus 900 may be part of a self-organizing / optimizing network (SON) node or other node, such as a node in a cloud.

[0123] Apparatus 900 may correspond to any of the other apparatuses described herein, such as anchor gNB Anchor Cell-B (170-B), gNB-DU-B 195-B, gNB-CU-B 196-B, anchor gNB Anchor Cell-A (170-A), gNB-DU-A 195-A, gNB-CU-A 196-A, NES gNB NES Cell (170- N), gNB-CU-NES 196-N, or gNB-DU-NES 195-B.

[0124] The apparatus 900 may also be distributed throughout the network (e.g. 100) including within and between apparatus 900 and any network element (such as a network control element (NCE) 190 and / or the RAN node 170 and / or UE 110).

[0125] Interface 912 enables data communication and signaling between the various itemsof apparatus 900, as shown in FIG. 9. For example, the interface 912 may be one or more buses such as address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like. Computer program code (e.g. instructions) 905, including control 906 may comprise object-oriented software configured to pass data or messages between objects within computer program code 905, or computer program code (e.g. instructions) 905, including control 906 may include functional, scripting, or procedural code. The apparatus 900 need not comprise each of the features mentioned, or may comprise other features as well. The various components of apparatus 900 may at least partially reside in a common housing 928, or a subset of the various components of apparatus 900 may at least partially be located in different housings, which different housings may include housing 928.

[0126] FIG. 10 shows a schematic representation of non-volatile memory media 1000a (e.g. computer / compact disc (CD) or digital versatile disc (DVD)) and 1000b (e.g. universal serial bus (USB) memory stick) and 1000c (e.g. cloud storage for downloading instructions and / or parameters 1002 or receiving emailed instructions and / or parameters 1002) storing instructions and / or parameters 1002 which when executed by a processor allows the processor to perform one or more of the steps of the methods described herein. Instructions and / or parameters 1002 may represent a computer readable medium.

[0127] FIG. 11 is an example method 1100 based on the examples described herein. At 1110, the method includes detecting a failure of an anchor cell. At 1120, the method includes transmitting, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell. At 1130, the method includes wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell. Method 1100 may be performed with RAN node 170, CU 196, gNB (Anchor) 170-A, Anchor Cell-A 170-A, gNB-CU-A 196- A, gNB (Anchor) 170-B, Anchor Cell-B 170-B, gNB- CU-B 196-B, NG-RAN nodei 170-1, NG-RAN node2170-2, Cell A access node 402, Cell A 404, or apparatus 900.

[0128] FIG. 12 is an example method 1200 based on the examples described herein. At 1210, the method includes receiving an indication of a failure of an anchor cell controlled with a network entity. At 1220, the method includes wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of thefailure of the anchor cell controlled with the network entity. At 1230, the method includes wherein the apparatus controls a network energy savings cell. At 1240, the method includes determining an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity. Method 1200 may be performed with RAN node 170, CU 196, gNB (NES) 170-N, NES Cell 170-N, gNB-CU-NES 196-N, NG-RAN nodei 170-1, NG-RAN node? 170-2, NES Cell access node 406, NES Cell 408, or apparatus 900.

[0129] FIG. 13 is an example method 1300 based on the examples described herein. At 1310, the method includes receiving, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell. At 1320, the method includes receiving, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell. Method 1300 may be performed with UE 110 or apparatus 900.

[0130] The following examples are provided and described herein.

[0131] Example 1. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: detect a failure of an anchor cell; and transmit, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

[0132] Example 2. The apparatus of example 1, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates whether or not the apparatus that controls the anchor cell is able to: transmit to a user equipment an uplink signal configuration, and operate in a restricted mode.

[0133] Example 3. The apparatus of example 2, wherein the restricted mode comprises the apparatus that controls the anchor cell not supporting transmission of system informationrelated to the network energy savings cell.

[0134] Example 4. The apparatus of any of examples 2 to 3, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, a request to continue to support the network energy savings cell in the restricted mode; and determine to continue to support the network energy savings cell in the restricted mode, in response to receiving, from the network entity that controls the network energy savings cell, the request to continue to support the network energy savings cell in the restricted mode.

[0135] Example 5. The apparatus of example 4, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, an updated uplink signal configuration to transmit to the user equipment ; and transmit to the user equipment the updated uplink signal configuration received from the network entity that controls the network energy savings cell.

[0136] Example 6. The apparatus of example 5, wherein the apparatus is further caused to: transmit, to the network entity that controls the network energy savings cell, a request for the updated uplink signal configuration to transmit to the user equipment; wherein the updated uplink signal configuration to transmit to the user equipment is received from the network entity that controls the network energy savings cell in response to transmitting to the network entity that controls the network energy savings cell the request for the updated uplink signal configuration to transmit to the user equipment.

[0137] Example 7. The apparatus of any of examples 2 to 6, wherein the apparatus is further caused to perform at least one of: determine a plurality of network energy savings cells that are requested with a random access procedure from a user equipment, and determine to periodically transmit, to the user equipment, the uplink signal configuration and system information for the plurality of network energy savings cells that are requested with the random access procedure from the user equipment, or determine to increase a frequency of transmissions, to a plurality of user equipment, of the uplink signal configuration and system information with lower periodicity, when the uplink signal configuration and system information for the network energy savings cell were previously being transmitted without an explicit request from the plurality of user equipment with a random access procedure.

[0138] Example 8. The apparatus of any of examples 1 to 7, wherein the information relatedto the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell is not able to operate normally.

[0139] Example 9. The apparatus of any of examples 1 to 8, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell has been deleted.

[0140] Example 10. The apparatus of any of examples 1 to 9, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, a request to deactivate the support of the network energy savings cell; and deactivate the support of the network energy savings cell, in response to receiving, from the network entity that controls the network energy savings cell, the request to deactivate the support of the network energy savings cell.

[0141] Example 11. The apparatus of any of examples 1 to 10, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, a request to deactivate the support of the network energy savings cell when the network entity that controls the network energy savings cell has disabled operation of providing system information related to the network energy savings sell; and disable uplink signal transmission and transmission of system information related to the network energy savings cell, in response to receiving, from the network entity that controls the network energy savings cell, the request to deactivate the support of the network energy savings cell when the network entity that controls the network energy savings cell has disabled operation of providing system information related to the network energy savings cell.

[0142] Example 12. The apparatus of any of examples 1 to 11, wherein the apparatus is further caused to: transmit, to a plurality of network entities that control respective network energy savings cells, the indication of the failure of the anchor cell controlled with the apparatus; wherein the network entity that controls the network energy savings cell is among the plurality of network entities that control the respective network energy savings cells.

[0143] Example 13. The apparatus of any of examples 1 to 12, wherein: the apparatus is associated with a first radio access network node, the network entity that controls the network energy savings cell is associated with a second radio access network node different from the first radio access network node, and the indication of the failure of the anchor cell controlledwith the apparatus is transmitted to the network entity that controls the network energy savings cell over an Xn interface.

[0144] Example 14. The apparatus of any of examples 1 to 13, wherein: the apparatus is associated with a radio access network node, the network entity that controls the network energy savings cell is associated with the radio access network node, and the indication of the failure of the anchor cell controlled with the apparatus is transmitted to the network entity that controls the network energy savings cell over an Fl interface.

[0145] Example 15. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and determine an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

[0146] Example 16. The apparatus of example 15, wherein the information related to the type of the failure of the anchor cell controlled with the network entity indicates whether or not the network entity that controls the anchor cell is able to: transmit to a user equipment an uplink signal configuration, and operate in a restricted mode.

[0147] Example 17. The apparatus of example 16, wherein the restricted mode comprises the network entity that controls the anchor cell not supporting transmission of system information related to the network energy savings cell.

[0148] Example 18. The apparatus of any of examples 16 to 17, wherein the apparatus is further caused to: determine that the anchor cell is to continue to support the network energy savings cell in the restricted mode; and transmit, to the network entity that controls the anchor cell, a request to continue to support the network energy savings cell in the restricted mode.

[0149] Example 19. The apparatus of example 18, wherein the apparatus is further caused to: transmit, to the network entity that controls the anchor cell, an updated uplink signal configuration to transmit to the user equipment.

[0150] Example 20. The apparatus of example 19, wherein the apparatus is further caused to: receive, from the network entity that controls the anchor cell, a request for the updated uplink signal configuration to transmit to the user equipment; wherein the updated uplink signal configuration to transmit to the user equipment is transmitted to the network entity that controls the anchor cell, in response to the request for the updated uplink signal configuration to transmit to the user equipment received from the network entity that controls the anchor cell.

[0151] Example 21. The apparatus of any of examples 15 to 20, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell is not able to operate normally.

[0152] Example 22. The apparatus of any of examples 15 to 21, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell has been deleted.

[0153] Example 23. The apparatus of any of examples 15 to 22, wherein the apparatus is further caused to: select another anchor cell controlled with another network entity to support the network energy savings cell; transmit, to the another network entity that controls the another anchor cell, a request to support the network energy savings cell; wherein the request to support the network energy savings cell transmitted to the another network entity that controls the another anchor cell comprises an uplink signal configuration and system information related to the network energy savings cell; and transmit, to the network entity that controls the anchor cell, a request to deactivate the support of the network energy savings cell.

[0154] Example 24. The apparatus of any of examples 15 to 23, wherein the apparatus is further caused to: disable operation of providing system information related to the network energy savings cell; and transmit, to the network entity that controls the anchor cell, a request to deactivate the support of the network energy savings cell when the apparatus that controls the network energy savings cell has disabled operation of providing system information related to the network energy savings cell.

[0155] Example 25. The apparatus of any of examples 15 to 24, wherein the indication of the failure of the anchor cell controlled with the network entity is received from: the network entity that controls the anchor cell, or an operations and management node.

[0156] Example 26. The apparatus of any of examples 15 to 25, wherein: the apparatus is associated with a first radio access network node, the network entity that controls the anchor cell is associated with a second radio access network node different from the first radio access network node, and the indication of the failure of the anchor cell controlled with the network entity is received from the network entity that controls the anchor cell over an Xn interface.

[0157] Example 27. The apparatus of any of examples 15 to 26, wherein: the apparatus is associated with a radio access network node, the network entity that controls the anchor cell is associated with the radio access network node, and the indication of the failure of the anchor cell controlled with the network entity is received from the network entity that controls the anchor cell over an Fl interface.

[0158] Example 28. An apparatus including: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; and receive, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

[0159] Example 29. The apparatus of example 28, wherein the transmission of the uplink signal configuration is received from the network entity that controls the anchor cell that supports the network energy savings cell when the network entity that controls the anchor cell that supports the network energy savings cell is operating in a restricted mode.

[0160] Example 30. The apparatus of any of examples 28 to 29, wherein the system information related to the network energy savings cell is not received from the network entity that controls the anchor cell that supports the network energy savings cell when the network entity that controls the anchor cell that supports the network energy savings cell is operating in a restricted mode.

[0161] Example 31. The apparatus of any of examples 28 to 30, wherein the apparatus is further caused to: request, using the uplink signal configuration, the system informationrelated to the network energy savings cell; wherein the system information related to the network energy saving cell is requested from the network entity that controls the anchor cell, the another network entity that controls the another anchor cell, or a network entity that controls the network energy savings cell.

[0162] Example 32. The apparatus of any of examples 28 to 31, wherein the transmission of the uplink signal configuration is received from the another network entity that controls the another anchor cell that supports the network energy savings cell when the another network entity that controls the another anchor cell that supports the network energy savings cell is operating in a restricted mode.

[0163] Example 33. The apparatus of any of examples 28 to 32, wherein the system information related to the network energy savings cell is not received from the another network entity that controls the another anchor cell that supports the network energy savings cell when the another network entity that controls the another anchor cell that supports the network energy savings cell is operating in a restricted mode.

[0164] Example 34. The apparatus of any of examples 28 to 33, wherein the apparatus comprises a user equipment, or a user equipment comprises the apparatus.

[0165] Example 35. A method including: detecting a failure of an anchor cell; and transmitting, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

[0166] Example 36. A method including: receiving an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and determining an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

[0167] Example 37. A method including: receiving, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savingscell; and receiving, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

[0168] Example 38. An apparatus including: means for detecting a failure of an anchor cell; and means for transmitting, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

[0169] Example 39. An apparatus including: means for receiving an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and means for determining an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

[0170] Example 40. An apparatus including: means for receiving, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; and means for receiving, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

[0171] Example 41. A computer readable medium including instructions stored thereon for performing at least the following: detecting a failure of an anchor cell; and transmitting, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

[0172] Example 42. A computer readable medium including instructions stored thereon for performing at least the following: receiving an indication of a failure of an anchor cellcontrolled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and determining an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

[0173] Example 43. A computer readable medium including instructions stored thereon for performing at least the following: receiving, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; and receiving, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

[0174] References to a ‘computer’, ‘processor’, etc. should be understood to encompass not only computers having different architectures such as single / multi-processor architectures and sequential or parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGAs), application specific circuits (ASICs), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc.

[0175] The memories as described herein may be implemented using any suitable data storage technology, such as semiconductor based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, non-transitory memory, transitory memory, fixed memory and removable memory. The memories may comprise a database for storing data.

[0176] The term “non-transitory,” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM).

[0177] As used herein, the term ‘circuitry’ may refer to the following: (a) hardware circuit implementations, such as implementations in analog and / or digital circuitry, and (b) combinations of circuits and software (and / or firmware), such as (as applicable): (i) a combination of processor(s) or (ii) portions of processor(s) / software including digital signal processor(s), software, and memories that work together to cause an apparatus to perform various functions, and (c) circuits, such as a microprocessor(s) or a portion of a microprocessor s), that require software or firmware for operation, even if the software or firmware is not physically present. As a further example, as used herein, the term ‘circuitry’ would also cover an implementation of merely a processor (or multiple processors) or a portion of a processor and its (or their) accompanying software and / or firmware. The term ‘circuitry’ would also cover, for example and if applicable to the particular element, a baseband integrated circuit or applications processor integrated circuit for a mobile phone or a similar integrated circuit in a server, a cellular network device, or another network device.

[0178] It should be understood that the foregoing description is only illustrative. Various alternatives and modifications may be devised by those skilled in the art. For example, features recited in the various dependent claims could be combined with each other in any suitable combination(s). In addition, features from different example embodiments described above could be selectively combined into a new example embodiment. Accordingly, this description is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.

[0179] The following acronyms and abbreviations that may be found in the specification and / or the drawing figures are given as follows (the abbreviations and acronyms may be appended / combined with each other or with other characters using e.g. a dash, hyphen, slash, letter, or number, and may be case insensitive):3 GPP third generation partnership project4G fourth generation5G fifth generation5GC 5G core networkAMF access and mobility management functionASIC application-specific integrated circuitBCH broadcast channelCD compact / computer discCGI cell global identifierConfig configurationCPU central processing unitCU central unit or centralized unitDC dual connectivityDL downlinkDSP digital signal processorDU distributed unitDVD digital versatile disc eNB evolved Node B (e.g., an LTE base station)EN-DC E-UTRAN new radio - dual connectivity en-gNB node providing NR user plane and control plane protocol terminations towards the UE, and acting as a secondary node in EN- DCE-UTRA evolved UMTS terrestrial radio access, i.e., the LTE radio access technologyE-UTRAN E-UTRA networkF 1 interface between the CU and the DUFPGA field-programmable gate array gNB generalized node B, base station for 5G / NR, i.e., a node providingNR user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GCHO handoverID identifierIE information elementI / F interfaceI / O input / outputLMF location management functionLTE long term evolution (4G)MAC medium access controlMIB master information blockMME mobility management entityMRO mobility robustness optimizationNCE network control elementNES network energy saving(s) ng or NG new generation ng-eNB new generation eNBNG-RAN new generation radio access networkNR new radioNW networkN / W networkOAM operations, administration and maintenance, or operations and managementOD on-demand0D-SIB1 on-demand SIB1Opt. optionPCI physical cell identifierPDA personal digital assistantPDCP packet data convergence protocolPHY physical layerPRACH physical random access channelRACH random access channelRAM random access memoryRAN radio access networkRANI RAN WG1RAN2 RAN WG2RAN3 RAN WG3Rel releaseRLC radio link controlROM read-only memoryRP RAN plenaryRRC radio resource controlRRM radio resource managementRU radio unitRx receive, or receiver, or receptionSDAP service data adaptation protocolSGW serving gatewaySIB system information blockSIB1 system information block type 1SMF session management functionSON self-organizing / optimizing networkSSB synchronization signal block, or synchronization signal and physical broadcast channel blockTRP transmission reception pointTx transmit, or transmitter, or transmissionUAV unmanned aerial vehicleUE user equipment (e.g., a wireless, typically mobile device)UI user interfaceUL uplinkUMTS Universal Mobile Telecommunications SystemUPF user plane functionUSB universal serial busWG working groupWID work item descriptionWUS wake up signalX2 network interface between RAN nodes and between RAN and the core networkXn network interface between NG-RAN nodes

Claims

CLAIMS1. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: detect a failure of an anchor cell; and transmit, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

2. The apparatus of claim 1, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates whether or not the apparatus that controls the anchor cell is able to: transmit to a user equipment an uplink signal configuration, and operate in a restricted mode.

3. The apparatus of claim 2, wherein the restricted mode comprises the apparatus that controls the anchor cell not supporting transmission of system information related to the network energy savings cell.

4. The apparatus of any of claims 2 to 3, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, a request to continue to support the network energy savings cell in the restricted mode; and determine to continue to support the network energy savings cell in the restricted mode, in response to receiving, from the network entity that controls the network energy savings cell, the request to continue to support the network energy savings cell in the restricted mode.

395. The apparatus of claim 4, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, an updated uplink signal configuration to transmit to the user equipment ; and transmit to the user equipment the updated uplink signal configuration received from the network entity that controls the network energy savings cell.

6. The apparatus of claim 5, wherein the apparatus is further caused to: transmit, to the network entity that controls the network energy savings cell, a request for the updated uplink signal configuration to transmit to the user equipment; wherein the updated uplink signal configuration to transmit to the user equipment is received from the network entity that controls the network energy savings cell in response to transmitting to the network entity that controls the network energy savings cell the request for the updated uplink signal configuration to transmit to the user equipment.

7. The apparatus of any of claims 2 to 6, wherein the apparatus is further caused to perform at least one of: determine a plurality of network energy savings cells that are requested with a random access procedure from a user equipment, and determine to periodically transmit, to the user equipment, the uplink signal configuration and system information for the plurality of network energy savings cells that are requested with the random access procedure from the user equipment, or determine to increase a frequency of transmissions, to a plurality of user equipment, of the uplink signal configuration and system information with lower periodicity, when the uplink signal configuration and system information for the network energy savings cell were previously being transmitted without an explicit request from the plurality of user equipment with a random access procedure.

8. The apparatus of any of claims 1 to 7, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell is not able to operate normally.

9. The apparatus of any of claims 1 to 8, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell has been deleted.

10. The apparatus of any of claims 1 to 9, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, a request to deactivate the support of the network energy savings cell; and deactivate the support of the network energy savings cell, in response to receiving, from the network entity that controls the network energy savings cell, the request to deactivate the support of the network energy savings cell.

11. The apparatus of any of claims 1 to 10, wherein the apparatus is further caused to: receive, from the network entity that controls the network energy savings cell, a request to deactivate the support of the network energy savings cell when the network entity that controls the network energy savings cell has disabled operation of providing system information related to the network energy savings sell; and disable uplink signal transmission and transmission of system information related to the network energy savings cell, in response to receiving, from the network entity that controls the network energy savings cell, the request to deactivate the support of the network energy savings cell when the network entity that controls the network energy savings cell has disabled operation of providing system information related to the network energy savings cell.

12. The apparatus of any of claims 1 to 11, wherein the apparatus is further caused to: transmit, to a plurality of network entities that control respective network energy savings cells, the indication of the failure of the anchor cell controlled with the apparatus; wherein the network entity that controls the network energy savings cell is among the plurality of network entities that control the respective network energy savings cells.

13. The apparatus of any of claims 1 to 12, wherein: the apparatus is associated with a first radio access network node, the network entity that controls the network energy savings cell is associated with a second radio access network node different from the first radio access network node, and the indication of the failure of the anchor cell controlled with the apparatus is transmitted to the network entity that controls the network energy savings cell over an Xn interface.

14. The apparatus of any of claims 1 to 13, wherein: the apparatus is associated with a radio access network node, the network entity that controls the network energy savings cell is associated with the radio access network node, and the indication of the failure of the anchor cell controlled with the apparatus is transmitted to the network entity that controls the network energy savings cell over an Fl interface.

15. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and determine an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the typeof failure of the anchor cell controlled with the network entity.

16. The apparatus of claim 15, wherein the information related to the type of the failure of the anchor cell controlled with the network entity indicates whether or not the network entity that controls the anchor cell is able to: transmit to a user equipment an uplink signal configuration, and operate in a restricted mode.

17. The apparatus of claim 16, wherein the restricted mode comprises the network entity that controls the anchor cell not supporting transmission of system information related to the network energy savings cell.

18. The apparatus of any of claims 16 to 17, wherein the apparatus is further caused to: determine that the anchor cell is to continue to support the network energy savings cell in the restricted mode; and transmit, to the network entity that controls the anchor cell, a request to continue to support the network energy savings cell in the restricted mode.

19. The apparatus of claim 18, wherein the apparatus is further caused to: transmit, to the network entity that controls the anchor cell, an updated uplink signal configuration to transmit to the user equipment.

20. The apparatus of claim 19, wherein the apparatus is further caused to: receive, from the network entity that controls the anchor cell, a request for the updated uplink signal configuration to transmit to the user equipment; wherein the updated uplink signal configuration to transmit to the user equipment is transmitted to the network entity that controls the anchor cell, in response to the request for the updated uplink signal configuration to transmit to the user equipment received from the network entity that controls the anchor cell.

21. The apparatus of any of claims 15 to 20, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell is not able to operate normally.

22. The apparatus of any of claims 15 to 21, wherein the information related to the type of the failure of the anchor cell controlled with the apparatus indicates that the anchor cell has been deleted.

23. The apparatus of any of claims 15 to 22, wherein the apparatus is further caused to: select another anchor cell controlled with another network entity to support the network energy savings cell; transmit, to the another network entity that controls the another anchor cell, a request to support the network energy savings cell; wherein the request to support the network energy savings cell transmitted to the another network entity that controls the another anchor cell comprises an uplink signal configuration and system information related to the network energy savings cell; and transmit, to the network entity that controls the anchor cell, a request to deactivate the support of the network energy savings cell.

24. The apparatus of any of claims 15 to 23, wherein the apparatus is further caused to: disable operation of providing system information related to the network energy savings cell; and transmit, to the network entity that controls the anchor cell, a request to deactivate the support of the network energy savings cell when the apparatus that controls the network energy savings cell has disabled operation of providing system information related to the network energy savings cell.

25. The apparatus of any of claims 15 to 24, wherein the indication of the failure of the anchor cell controlled with the network entity is received from: the network entity that controls the anchor cell, or an operations and management node.

26. The apparatus of any of claims 15 to 25, wherein: the apparatus is associated with a first radio access network node, the network entity that controls the anchor cell is associated with a second radio44access network node different from the first radio access network node, and the indication of the failure of the anchor cell controlled with the network entity is received from the network entity that controls the anchor cell over an Xn interface.

27. The apparatus of any of claims 15 to 26, wherein: the apparatus is associated with a radio access network node, the network entity that controls the anchor cell is associated with the radio access network node, and the indication of the failure of the anchor cell controlled with the network entity is received from the network entity that controls the anchor cell over an Fl interface.

28. An apparatus comprising: at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the apparatus at least to: receive, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; and receive, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

29. The apparatus of claim 28, wherein the transmission of the uplink signal configuration is received from the network entity that controls the anchor cell that supports the network energy savings cell when the network entity that controls the anchor cell that supports the network energy savings cell is operating in a restricted mode.

30. The apparatus of any of claims 28 to 29, wherein the system information related to the network energy savings cell is not received from the network entity that controls the anchor45cell that supports the network energy savings cell when the network entity that controls the anchor cell that supports the network energy savings cell is operating in a restricted mode.

31. The apparatus of any of claims 28 to 30, wherein the apparatus is further caused to: request, using the uplink signal configuration, the system information related to the network energy savings cell; wherein the system information related to the network energy saving cell is requested from the network entity that controls the anchor cell, the another network entity that controls the another anchor cell, or a network entity that controls the network energy savings cell.

32. The apparatus of any of claims 28 to 31, wherein the transmission of the uplink signal configuration is received from the another network entity that controls the another anchor cell that supports the network energy savings cell when the another network entity that controls the another anchor cell that supports the network energy savings cell is operating in a restricted mode.

33. The apparatus of any of claims 28 to 32, wherein the system information related to the network energy savings cell is not received from the another network entity that controls the another anchor cell that supports the network energy savings cell when the another network entity that controls the another anchor cell that supports the network energy savings cell is operating in a restricted mode.

34. The apparatus of any of claims 28 to 33, wherein the apparatus comprises a user equipment, or a user equipment comprises the apparatus.

35. A method comprising: detecting a failure of an anchor cell; and transmitting, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

36. A method comprising: receiving an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and determining an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

37. A method comprising: receiving, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; and receiving, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

38. An apparatus comprising: means for detecting a failure of an anchor cell; and means for transmitting, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

39. An apparatus comprising: means for receiving an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and means for determining an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

40. An apparatus comprising: means for receiving, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; and means for receiving, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

41. A computer readable medium comprising instructions stored thereon for performing at least the following: detecting a failure of an anchor cell; and transmitting, to a network entity that controls a network energy savings cell, an indication of the failure of the anchor cell; wherein the indication of the failure of the anchor cell comprises information related to a type of the failure of the anchor cell.

42. A computer readable medium comprising instructions stored thereon for performing at least the following: receiving an indication of a failure of an anchor cell controlled with a network entity; wherein the indication of the failure of the anchor cell controlled with the network entity comprises information related to a type of the failure of the anchor cell controlled with the network entity; wherein the apparatus controls a network energy savings cell; and determining an operation associated with providing at least one user equipment assistance for the network energy savings cell, based on the information related to the type of failure of the anchor cell controlled with the network entity.

43. A computer readable medium comprising instructions stored thereon for performing at least the following: receiving, from a network entity that controls an anchor cell that supports a network energy savings cell, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell; and receiving, from another network entity that controls another anchor cell that supports the network energy savings cell when the anchor cell that supports the network energy savings cell has failed, at least one or more of: a transmission of an uplink signal configuration, or system information related to the network energy savings cell.

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