Passive mode transition of user equipment based on control plane monitoring

Abstract

User equipment (UE), methods and software for selectively transmitting data to a mobile network. In one embodiment, when the UE is in non-connected mode, the UE identifies data buffered for one or more applications running on the UE, determines the number of other UEs receiving signaling messages for transitioning from non-connected mode to connected mode on a control plane, and estimates a load on the control plane based on the number of other UEs receiving signaling messages for transitioning from non-connected mode to connected mode. When the load on the control plane exceeds a threshold, the UE defers transitioning from non-connected mode to connected mode to delay transmission of data from the UE to the mobile network over a radio interface.

Description

Technical Field

[0001] The present disclosure relates to the field of communication systems, and in particular to mobile devices accessing services from a mobile network. Background Art

[0002] Mobile devices (also referred to herein as user equipment (UE)) provide clients with access to various types of data services from a mobile network. A typical mobile device may include multiple applications running simultaneously that request to send or receive data to or from the mobile network over a radio interface. Due to the variety of different mobile devices and the number of data services available to clients, the use of data services may increase, especially as next generation (e.g., fifth generation (5G)) networks come online with higher speeds and connectivity.

[0003] In Long Term Evolution (LTE), a UE may be in an idle mode with no radio bearers established, or in a connected mode with radio bearers established. The UE will be in idle mode when initially powered on, after a period of inactivity, etc. In order to transfer data from the UE to the mobile network, the UE transitions from idle mode to connected mode. Signaling messages, such as signaling messages for transitioning the UE from idle mode to connected mode, are transmitted via the protocols of the control plane. The number of signaling messages may exceed the capacity of the control plane, especially when a large number of UEs are located in a cell. This may be a problem because the UE's connection to the mobile network may be prohibited or delayed. Therefore, there is a need to identify ways for UEs to efficiently share control plane resources. Summary of the invention

[0004] Described herein is a UE (and associated methods and software) that estimates the load on the control plane and postpones the transition from a non-connected mode (e.g., idle mode) to a connected mode when the load exceeds a threshold. The UE typically includes one or more applications that request data to be transferred to a mobile network. If a user is actively using an application, the application can request data to be transferred to the mobile network based on input from the user (commonly referred to as foreground data). Even if the user is not actively using the application, the application can request data to be transferred to the mobile network (commonly referred to as unattended or background data). The UE as described herein is configured to postpone the transition from non-connected mode to connected mode to transmit foreground data and / or background data based on the load on the control plane. This is beneficial because the UE "passively" transitions from non-connected mode to connected mode and delays data transmission when the control plane is at or near its limit. Passive mode transitions may be particularly beneficial for processing background data. It is estimated that background data transmission may be a large portion of the UE's connection request. The UE as described herein is able to delay background data transmission when the control plane is at or near its limit, so that the signaling messages required for background data transmission do not endanger control plane resources.

[0005] One embodiment includes a UE configured to communicate with a mobile network over a radio interface. The UE includes at least one processor and at least one memory, the at least one memory including computer program code executable by the processor. The processor is configured to cause the UE to: when the UE is in a non-connected mode, identify data buffered for one or more applications running on the UE, determine the number of other UEs that receive signaling messages for transitioning from the non-connected mode to the connected mode on a control plane (when in the non-connected mode), estimate a load on the control plane based on the number of other UEs that receive signaling messages for transitioning from the non-connected mode to the connected mode, and when the load on the control plane exceeds a threshold, defer the UE's transition from the non-connected mode to the connected mode to delay transmission of data from the UE to the mobile network over the radio interface.

[0006] In another embodiment, the processor is further configured to cause the UE to: transition from the non-connected mode to the connected mode when the load on the control plane does not exceed a threshold, and initiate transmission of data from the UE to the mobile network over the radio interface.

[0007] In another embodiment, the data buffered for the application includes background data.

[0008] In another embodiment, the data buffered for at least one of the applications includes machine type communication (MTC) data.

[0009] In another embodiment, the processor is further configured to cause the UE to monitor the paging message to determine the number of other UEs identified in the paging message.

[0010] In another embodiment, the processor is further configured to cause the UE to monitor the random access message to determine the number of other UEs that receive the random access response message.

[0011] In another embodiment, the processor is configured to cause the UE to determine the number of other UEs receiving the signaling message in a first time interval, and the threshold is a percentage of an average load on the control plane in a second time interval greater than the first time interval.

[0012] Another embodiment includes a method of operating a UE to communicate with a mobile network over a radio interface. The method includes: when the UE is in a non-connected mode, identifying data buffered for one or more applications running on the UE, determining (when the UE is in the non-connected mode) a number of other UEs receiving a signaling message on a control plane for transitioning from the non-connected mode to the connected mode, estimating a load on the control plane based on the number of other UEs receiving the signaling message for transitioning from the non-connected mode to the connected mode, and when the load on the control plane exceeds a threshold, deferring the transition of the UE from the non-connected mode to the connected mode to delay transmission of data from the UE to the mobile network over the radio interface.

[0013] In another embodiment, the method further comprises: when the load on the control plane does not exceed a threshold, transitioning the UE from a non-connected mode to a connected mode, and initiating transmission of data from the UE to the mobile network over the radio interface.

[0014] In another embodiment, determining the number of other UEs receiving the signaling message on the control plane for transitioning from the non-connected mode to the connected mode includes monitoring a paging message to determine the number of other UEs identified in the paging message.

[0015] In another embodiment, determining the number of other UEs receiving a signaling message for transitioning from the non-connected mode to the connected mode on the control plane includes monitoring random access messages to determine the number of other UEs receiving random access response messages.

[0016] In another embodiment, determining the number of other UEs receiving signaling messages on the control plane includes determining the number of other UEs receiving signaling messages in a first time interval, and the threshold is a percentage of an average load on the control plane in a second time interval greater than the first time interval.

[0017] Another embodiment includes a non-transitory computer-readable medium embodying programming instructions executed by a processor. The instructions direct the processor to implement a method of operating a UE, the UE being configured to communicate with a mobile network over a radio interface. The method includes: when the UE is in a non-connected mode, identifying data buffered for one or more applications running on the UE, determining (when the UE is in the non-connected mode) the number of other UEs receiving signaling messages for transitioning from the non-connected mode to the connected mode on a control plane, estimating a load on the control plane based on the number of other UEs receiving signaling messages for transitioning from the non-connected mode to the connected mode, and when the load on the control plane exceeds a threshold, deferring the UE's transition from the non-connected mode to the connected mode to delay transmission of data from the UE to the mobile network over the radio interface.

[0018] Another embodiment includes a UE configured to communicate with a mobile network over a radio interface. The UE includes: a component for identifying data buffered for one or more applications running on the UE when the UE is in a non-connected mode, a component for receiving a number of other UEs on a control plane for a signaling message for transitioning from the non-connected mode to the connected mode, a component for estimating a load on the control plane based on the number of other UEs receiving the signaling message for transitioning from the non-connected mode to the connected mode, and a component for deferring the transition of the UE from the non-connected mode to the connected mode to delay transmission of data from the UE to the mobile network over the radio interface when the load on the control plane exceeds a threshold.

[0019] The above summary of the invention provides a basic understanding of some aspects of the specification. This summary of the invention is not an extensive overview of the specification. It is neither intended to identify the key or essential elements of the specification, nor to define any scope of the specific embodiments of the specification or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to a more detailed description presented later. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Some embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings.In all drawings, the same reference number represents the same element or the same type of element.

[0021] Figure 1 A mobile network in an illustrative embodiment is shown.

[0022] Figure 2 An Evolved Packet Core (EPC) network is shown.

[0023] Figure 3 A non-roaming architecture of a next generation network is shown.

[0024] Figure 4The radio protocol stack is shown.

[0025] Figure 5 is a message diagram illustrating a contention-based random access procedure.

[0026] Figure 6 is a message diagram illustrating a contention-free random access procedure.

[0027] Figure 7 The RRC state machine is shown.

[0028] Figure 8 is a message diagram illustrating RRC connection establishment.

[0029] Fig. 9 is a message diagram illustrating RRC connection release.

[0030] Fig.10 is a block diagram of a UE in an illustrative embodiment.

[0031] Fig.11 is a flow chart showing a method of processing data transmission from a UE to a network in an illustrative embodiment.

[0032] Fig.12 is a flow chart showing a method of estimating load on a control plane in an illustrative embodiment.

[0033] Fig.13 is a flow chart illustrating another method of estimating load on a control plane in an illustrative embodiment. DETAILED DESCRIPTION

[0034] The accompanying drawings and the following description illustrate specific exemplary embodiments. It should therefore be understood that those skilled in the art will be able to design various arrangements that, although not explicitly described or shown herein, embody the principles of the embodiments and are included within the scope of the embodiments. In addition, any examples described herein are intended to help understand the principles of the embodiments and will be interpreted as not being limited by such specifically enumerated examples and conditions. As a result, (multiple) inventive concepts are not limited to the specific embodiments or examples described below, but are limited by the claims and their equivalents.

[0035] Figure 1 A mobile network 100 in an illustrative embodiment is shown. Mobile network 100 (also referred to as a cellular network) is a type of network in which the final link is wireless and provides voice and / or data services to multiple devices. Mobile network 100 may be a third generation (3G), fourth generation (4G), and / or next generation network (e.g., 5G).

[0036] Mobile network 100 is shown as providing communication services to UE 110 (along with other UEs not shown). UE 110 may enable voice services, data services, machine-to-machine (M2M) or machine-type communication (MTC) services, and / or other services. UE 110 may be an end-user device such as a mobile phone (e.g., a smartphone), a tablet or PDA, a computer with a mobile broadband adapter, etc.

[0037] The mobile network 100 includes one or more radio access networks (RAN) 120 that communicate with the UE 110 through a radio interface 122. The RAN 120 may support Evolved UMTS Terrestrial Radio Access Network (E-UTRAN) access, Wireless Local Area Network (WLAN) access, fixed access, satellite radio access, new radio access technology (RAT), etc. As an example, the RAN 120 may include an E-UTRAN or a Next Generation RAN (NG-RAN) that includes one or more base stations 124 that are dispersed over a certain geographical area. The base station 124 may include an entity that communicates with the UE on a licensed spectrum using radio communication technology and interfaces the UE with the core network. The base station 124 in the E-UTRAN is called an evolved Node B (eNodeB). The base station 124 in the NG-RAN is called a gNodeB (NR base station) and / or an ng-eNodeB (LTE base station supporting a 5G core network). As another example, the RAN 120 may include a WLAN that includes one or more wireless access points (WAPs) 125. WLAN is a network in which UE can connect to a local area network (LAN) through a wireless (radio) connection. WAP 125 is a node that uses radio communication technology to communicate with UE on an unlicensed spectrum and provides UE with access to a core network. An example of WAP 125 is a WiFi access point operating on a 2.4 GHz or 5 GHz radio frequency band. The term "base station" used herein may refer to eNodeB, gNodeB and ng-eNodeB, WAP, etc.

[0038] In this embodiment, the RAN 120 also includes one or more control plane processors 128. The control plane processor 128 represents a device that processes signaling messages on the control plane. For example, the control plane processor 128 can process signaling messages for transitioning the UE 110 from a non-connected mode (e.g., idle mode) to a connected mode, as will be described in more detail below. The control plane processor 128 can be implemented as part of a base station 124 (e.g., an eNodeB), or can be a device shared by multiple base stations 124.

[0039] UE 110 is able to attach to a cell 126 of RAN 120 to access core network 130. Thus, RAN 120 represents a radio interface between UE 110 and core network 130. Core network 130 is a central part of mobile network 100, which provides various services to customers connected by RAN 120. One example of core network 130 is an evolved packet core (EPC) network proposed by 3GPP for LTE. Another example of core network 130 is a 5G core network proposed by 3GPP. Core network 130 includes network elements 132, which may include servers, devices, apparatuses, or equipment (including hardware) that provide services for UE 110. Network elements 132 in the EPC network may include a mobility management entity (MME), a serving gateway (S-GW), a packet data network gateway (P-GW), and the like. The network elements 132 in the 5G network may include an access and mobility management function (AMF), a session management function (SMF), a policy control function (PCF), an application function (AF), a user plane function (UPF), etc.

[0040] Figure 2An evolved packet core (EPC) network 200 is shown, which is the core network of LTE. The EPC network 200 includes a mobility management entity (MME) 214, a serving gateway (S-GW) 215, a packet data network gateway (P-GW) 216, a home subscriber server (HSS) 217, and a policy and charging rules function (PCRF) 218, but may include other elements not shown, such as an IP multimedia subsystem (IMS) application server. Within the EPC network 200, user data (also referred to as a "user plane") and signaling (also referred to as a "control plane") are separated. The MME 214 handles the control plane within the EPC network 200. For example, the MME 214 handles signaling related to mobility and security of E-UTRAN access. The MME 214 is responsible for tracking and paging UE 110 in idle mode. The S-GW 215 and P-GW 216 handle the user plane. The S-GW 215 and the P-GW 216 transmit data traffic between the UE 110 and the external data network 240 (DN or Packet Data Network (PDN)). The S-GW 215 is the interconnection point between the radio side and the EPC network 200, and serves the UE 110 by routing incoming and outgoing IP packets. The S-GW 215 is also the anchor point for intra-LTE mobility (i.e., in the case of handover between eNodeBs) and between LTE and other 3GPP accesses. The P-GW 216 is the interconnection point between the EPC network 200 and the external data network 240 (i.e., the entry or exit point of the data network 240), and routes packets in and out of the data network 240. The HSS 217 is a database that stores user-related and subscriber-related information. The PCRF 218 provides a policy and charging control (PCC) solution in the EPC network 200, and is a node or entity of the EPC network 200 that formulates PCC rules for services requested by end users.

[0041] The MME 214 is connected to the RAN 120 (i.e., eNodeB) through an S1-MME interface, and the S-GW 215 is connected to the RAN 120 through an S1-U interface. The MME 214 is connected to the S-GW 215 through an S11 interface, and to the HSS 217 through an S6a interface. The PCRF 218 is connected to the P-GW 216 through a Gx interface, which provides for the transmission of policy and charging rules from the PCRF 218 to a policy and charging enforcement function (PCEF) in the P-GW 216. The PCRF 218 is connected to the S-GW 215 through a Gxx interface, and the S-GW 215 is connected to the P-GW 216 through an S5 interface.

[0042] Figure 3 A non-roaming architecture 300 of a next generation network is shown. Figure 3 The architecture in is a reference point representation, as further described in 3GPP TS 23.501 (v16.1.0) (which is incorporated herein by reference as if fully included herein). The architecture 300 consists of network functions (NFs) of the core network, and the network functions of the control plane are separated from the user plane. The control plane of the core network includes an authentication server function (AUSF) 310, a unified data management (UDM) 312, a network slice selection function (NSSF) 313, an access and mobility management function (AMF) 314, a session management function (SMF) 316, a policy control function (PCF) 318, and an application function (AF) 320. The user plane of the core network includes one or more user plane functions (UPF) 324 that communicate with the data network 240. The UE 110 is able to access the control plane and the user plane of the core network through the (R)AN 120.

[0043] AUSF 310 is configured to support authentication of UE 110. UDM 312 is configured to store subscription data / information for UE 110. UDM 312 can store three types of user data: subscription, policy and session related context (e.g., UE location). AMF 314 is configured to provide UE-based authentication, authorization, mobility management, etc. SMF 316 is configured to provide the following functions: session management (SM), UE Internet Protocol (IP) address allocation and management, selection and control of (multiple) UPFs, termination of interfaces towards PCF 318, policy enforcement and control part of quality of service (QoS), lawful interception, termination of SM part of NAS messages, downlink data notification (DNN), roaming functions, processing local enforcement of QoS for application service level agreements (SLAs), charging data collection and charging interfaces, etc. If UE 110 has multiple sessions, different SMFs can be assigned to each session to manage them individually and possibly provide different functions for each session. PCF 318 is configured to support a unified policy framework to manage network behavior and provide policy rules to control plane functions for QoS enforcement, charging, access control, service routing, etc. AF 320 provides information about packet flows to PCF 318. Based on this information, PCF 318 is configured to determine policy rules about mobility and session management so that AMF 314 and SMF 316 operate normally.

[0044] UPF 324 supports various user plane operations and functions, such as packet routing and forwarding, service processing (e.g., QoS implementation), anchor point for intra-RAT / inter-RAT mobility (if applicable), packet inspection and policy rule implementation, lawful interception (UP collection), service statistics and reporting, etc. The data network 240 is not part of the core network and provides Internet access, operator services, third-party services, etc. For example, the International Telecommunication Union (ITU) divides 5G mobile network services into three categories: enhanced mobile broadband (eMBB), ultra-reliable low-latency communication (uRLLC), and massive machine type communication (mMTC) or massive Internet of Things (MIoT). eMBB focuses on services with high bandwidth requirements, such as HD video, virtual reality (VR), and augmented reality (AR). uRLLC focuses on delay-sensitive services, such as autonomous driving and remote management. mMTC and MIoT focus on services with high connection density requirements, such as smart cities and smart agriculture. The data network 240 can be configured to provide these and other services.

[0045] The architecture 300 includes the following reference points. The N1 reference point is implemented between the UE 110 and the AMF 314. The N2 reference point is implemented between the (R)AN 120 and the AMF 314. The N3 reference point is implemented between the (R)AN 120 and the UPF 324. The N4 reference point is implemented between the SMF 316 and the UPF 324. The N5 reference point is implemented between the PCF 318 and the AF 320. The N6 reference point is implemented between the UPF 324 and the data network 240. The N7 reference point is implemented between the SMF 316 and the PCF 318. The N8 reference point is implemented between the UDM 312 and the AMF 314. The N9 reference point is implemented between the two UPFs 324. The N10 reference point is implemented between the UDM 312 and the SMF 316. The N11 reference point is implemented between the AMF 314 and the SMF 316. The N12 reference point is implemented between the AMF 314 and the AUSF 310. The N13 reference point is implemented between the UDM 312 and the AUSF 310. The N14 reference point is implemented between two AMFs. In the case of a non-roaming scenario, the N15 reference point is implemented between the PCF 318 and the AMF 314. The N22 reference point is implemented between the NSSF 313 and the AMF 314.

[0046] Figure 4A radio protocol stack 400 is shown, such as for the radio interface 122. As described herein, the user plane 412 includes a set of protocols for transmitting actual user data over the network, and the control plane 414 includes protocols for controlling and establishing user connections and bearers within the network. For the user plane 412 and the control plane 414, the radio protocol stack 400 includes a physical (PHY) layer 401, a medium access control (MAC) layer 402, a radio link control (RLC) layer 403, and a packet data convergence protocol (PDCP) layer 404. The control plane 414 additionally includes a radio resource control (RRC) layer 405 and a non-access stratum (NAS) layer 406.

[0047] The physical layer 401 carries all information from the MAC transport channel through the radio interface. Data and signaling messages are carried on physical channels between different layers of the physical layer 401. Physical channels are divided into physical data channels and physical control channels. Physical data channels may include physical downlink shared channel (PDSCH), physical broadcast channel (PBCH), physical multicast channel (PMCH), physical uplink shared channel (PUSCH) and physical random access channel (PRACH). Physical control channels may include physical control format indicator channel (PCFICH), physical hybrid ARQ indicator channel (PHICH), physical downlink control channel (PDCCH) and physical uplink control channel (PUCCH).

[0048] The MAC layer 402 is responsible for mapping between logical channels and transport channels, multiplexing MAC SDUs from one or different logical channels onto transport blocks (TBs) for delivery to the physical layer on transport channels, demultiplexing MAC SDUs from one or different logical channels from transport blocks (TBs) delivered from the physical layer on transport channels, scheduling information reporting, error correction through HARQ, priority handling between UEs through dynamic scheduling, priority handling between logical channels of one UE, and logical channel priority. The RLC layer 403 is responsible for transmission of upper layer PDUs, error correction through ARQ, and concatenation, segmentation, and reassembly of RLC SDUs. The RLC layer 403 is also responsible for resegmentation of RLC data PDUs, reordering of RLC data PDUs, duplicate detection, RLC SDU discard, RLC reestablishment, and protocol error detection. The PDCP layer 404 is responsible for header compression and decompression of IP data, data transmission (user plane or control plane), maintenance of PDCP sequence number (SN), in-sequence delivery of upper layer PDUs when the lower layer is re-established, deduplication of lower layer SDUs when the lower layer is re-established for radio bearers mapped on RLC AM, encryption and decryption of user plane data and control plane data, integrity protection and integrity verification of control plane data, timer-based discard, duplicate discard, etc. The RRC layer 405 is responsible for broadcasting of system information related to NAS, broadcasting of system information related to the access layer (AS), paging, establishment, maintenance and release of RRC connection between UE and RAN, security functions (including key management, establishment, configuration, maintenance and release of point-to-point radio bearers (RB)). The NAS layer 406 represents the highest layer of the control plane 414 between the UE and the core network (e.g., MME / AMF), and supports the mobility and session management procedures of the UE to establish and maintain the IP connection between the UE and the core network.

[0049] In order to access services from a mobile network, the UE performs cell selection by measuring the received signal strength indicator (RSSI) of a set of channels. Channels whose RSSI exceeds a threshold are considered candidate cells for the UE. The UE decodes the primary synchronization signal (PSS) and the secondary synchronization signal (SSS) to achieve downlink frame synchronization, and identifies the physical layer cell identity (PCI) for each candidate cell. The UE also receives system information for each cell by decoding the master information block (MIB) and the system information block (SIB) broadcast by the cell through a broadcast channel. The MIB carries the physical layer information of the cell, which helps the UE receive additional SIBs (e.g., system bandwidth). The SIB carries other system information, such as the public land mobile network (PLMN) ID, cell ID, tracking area code (TAC), cell barring information (e.g., whether the UE is prohibited from staying in the cell), etc. The UE then selects one of the candidate cells based on its cell selection criteria and stays on the selected cell. At this point, the UE is synchronized with the mobile network in the downlink (DL) direction.

[0050] In order to synchronize with the mobile network in the uplink (UL) direction, the UE performs a random access procedure (RAP) over PRACH. The random access procedure may occur at the initial access of the UE, during the RRC connection re-establishment process, at handover, when UL synchronization is lost, when the UE does not have any PUCCH resources available for scheduling requests, when timing advance is required, etc. Figure 5 1 is a message diagram showing a contention-based random access procedure. The random access procedure includes a communication between the UE 110 and the eNodeB 524 (which is as shown in FIG. Figure 110 (an example of a base station 124 in FIG. 1 ). For message 1, UE 110 randomly selects one of 64 available RACH preambles for the cell and sends the preamble to eNodeB 524. The RACH preamble is a specific pattern or signature, and the preamble value distinguishes requests from different devices. For message 2, eNodeB 524 calculates the identity of UE 110 (i.e., the random access radio network temporary identity (RA-RNTI)) from the RACH preamble, and sends a random access response (RAR) to UE 110 on the DL-SCH (downlink shared channel) addressed to the RA-RNTI. The RAR includes a temporary cell radio network temporary identity (C-RNTI) given by the eNodeB 524 for further communication, a timing advance value (so that UE 110 can change its timing to compensate for the round-trip delay caused by the distance between UE 110 and eNodeB 524), and uplink granted resources (so that UE 110 can use UL-SCH (uplink shared channel)). For message 3, UE 110 sends an RRC connection request message to eNodeB 524 using UL-SCH. The RRC connection request message includes an identity of UE 110 (e.g., a temporary mobile subscriber identity (TMSI) or a random value). If UE 110 has previously been connected to the network, the TMSI is used, and when UE 110 initially connects to the network, the random value is used. The RRC connection request message also includes a connection establishment cause, which indicates the reason why UE 110 needs to connect to the network. For message 4, eNodeB 524 responds to UE 110 with a contention resolution message to confirm successful reception of the RRC connection request message. The contention resolution message is addressed toward the TMSI value or random number and includes a new C-RNTI for further communications.

[0051] Figure 6is a message diagram illustrating a contention-free random access procedure. Unlike the contention-based example in which UE 110 selects one of 64 available RACH preambles, eNodeB 524 actually allocates the preamble to UE 110. Therefore, eNodeB 524 sends the preamble to UE 110. For message 1, UE 110 sends the preamble back to eNodeB 524. eNodeB 524 calculates the identity of UE 110 (i.e., RA-RNTI) based on the RACH preamble. For message 2, eNodeB 524 sends a random access response (RAR) to UE 110 on the DL-SCH addressed to the RA-RNTI. The RAR includes a temporary C-RNTI given by eNodeB 524 for further communication, a timing advance value (so that UE 110 can change its timing to compensate for the round-trip delay due to the distance between UE 110 and eNodeB 524), and uplink granted resources (so that UE 110 can use UL-SCH).

[0052] After the random access procedure, the UE 110 needs to establish an RRC connection with the RAN 120 (e.g., eNodeB) to access services from the mobile network 100. The RRC layer controls the communication between the UE and the eNodeB at the radio interface. The RRC is the highest layer in the control plane of the access stratum (AS). The RRC also transmits NAS messages located above the RRC layer. NAS messages are used to control the communication between the UE and the core network. The RRC layer performs the following functions: broadcasting of system information, paging, establishment / release of RRC connections, transmission of NAS information, AS security configuration, transmission of UE radio access capabilities, measurement configuration and reporting, and mobility control. The RRC protocol is described in 3GPP TS 36.331 (v15.6.0) (which is incorporated herein by reference as if fully included herein).

[0053] The operation of the RRC is directed by a state machine that defines a particular state or mode of the UE 110 . Figure 7The RRC state machine is shown. The RRC connection transitions between a non-connected mode 702 (e.g., RRC_IDLE) and a connected mode 704 (e.g., RRC_CONNECTED). There may be additional modes, states, or stages, such as an inactive mode (e.g., RRC_INACTIVE), an additional connected mode, and the like. However, for the purposes of discussion, the UE 110 is considered to be in a connected mode 704 or a non-connected mode 702. When the UE 110 is in the connected mode 704, an RRC connection is established and the UE 110 is able to transmit data to and receive data from the eNodeB. With the establishment of the RRC connection, a signaling radio bearer 1 (SRB1) is established between the UE 110 and the eNodeB. A signaling radio bearer is defined as a radio bearer used only for the transmission of RRC and NAS messages. Three SRB types are defined for E-UTRA: SRB0, SRB1, and SRB2. SRB0 is used to transmit RRC messages associated with common control logical channels. SRB1 is used to transmit RRC messages, including piggybacked NAS messages associated with a dedicated control logical channel. SRB2 is used to transmit NAS messages using a dedicated control logical channel, but has a lower priority than SRB1 and is configured after security activation. When the UE 110 is in connected mode 704, such as after a NAS attach procedure, one or more dedicated data radio bearers (DRBs) may also be established.

[0054] For example, during an inactive period, the UE 110 may transition to the non-connected mode 702, such as to reduce UE power consumption. The non-connected mode 702 may also be referred to as an idle mode. The number of processes that the UE 110 needs to perform in the non-connected mode 702 is significantly less than in the connected mode. For example, the UE 110 in the non-connected mode 702 may be active for a short period of time to perform a limited number of processes, such as monitoring of incoming calls and measurements of mobility, but generally remains inactive for most of the time. When the UE 110 is in the non-connected mode 702, no RRC connection is established for the UE 110. In other words, the RRC connection has not been established (e.g., in a power-on scenario), has been released, has been suspended, etc., and no SRB1 is established between the UE 110 and the eNodeB. When in the non-connected mode 702, the presence of the UE 110 may be unknown at the cell level because the eNodeB does not have any context about the UE 110. The location of the UE 110 in the non-connected mode 702 is known to the core network 130 at the tracking area level.

[0055] Figure 8is a message diagram illustrating RRC connection establishment. When the upper layer requests to establish a signaling connection when the UE 110 is in idle mode, the RRC connection establishment process is initiated. The UE 110 sends an RRC connection request message to the eNodeB 524, such as on SRB0. The eNodeB 524 performs admission control to determine whether the RRC connection is allowed for the UE 110. If so, the eNodeB 524 sends an RRC connection establishment message to the UE 110. The RRC connection establishment message includes RLC and MAC parameters for establishing SRB1. The UE 110 applies the configuration from the RRC connection establishment message and transitions to connected mode. The UE 110 then sends an RRC connection establishment completion message to the eNodeB 524.

[0056] Fig. 9 is a message diagram illustrating RRC connection release. When UE 110 is in connected mode, the release of the RRC connection is usually initiated by RAN 120. When eNodeB 524 detects that UE 110 does not have any business to send and receive within a defined time period (usually referred to as an inactive timer (e.g., 10 seconds, 20 seconds, etc.)), eNodeB 524 can initiate a process for releasing the RRC connection. eNodeB 524 transmits an RRC connection release message to UE 110 to transition UE 110 to non-connected or idle mode. In this state, UE 110 has no connection with core network 130 because existing connections (such as SRBs and DRBs) are removed. In addition, context information related to UE 110 can be removed from RAN 120. However, if UE 110 transitions to another mode other than idle (e.g., inactive mode), the context information can be maintained in RAN 120.

[0057] When in non-connected or idle mode, UE 110 will continue to perform cell reselection and tracking area update (TAU). UE 110 will also periodically monitor the downlink channel of the selected cell to obtain paging messages. Paging messages are initiated by the core network 130 to locate idle UEs when there is DL traffic being buffered. In order to monitor paging messages, UE 110 synchronizes with RAN 120 in the DL direction and decodes SIB to read DL communications from the cell. If DL data (i.e., idle) for UE 110 is received, the core network 130 will buffer the data and re-establish a bearer connection with UE 110. The core network 130 will initiate paging of the cell in the tracking area to determine the cell where UE 110 is located, such as through MME, AMF, etc. The base station 124 in the tracking area will send a paging message to UE 110 during the UE's listening interval.

[0058] One or more of the UE 110 (and other UEs not shown) may need to exit non-connected or idle mode, such as when new DL data is buffered in the core network 130, or new UL data is buffered in the UE 110. In order to transition from non-connected mode to connected mode, the UE 110 will use a random access procedure to UL synchronize with their cell and attempt to establish an RRC connection using an RRC connection establishment procedure. When a large number of UEs 110 perform random access procedures and RRC connection establishment procedures in a cell, the control plane 414 may become overloaded. According to the embodiments described herein, when the control plane is in or close to an overload condition, the UE 110 can delay exiting the non-connected mode. As an overview, the UE 110 monitors the control plane 414 to determine the number of signaling messages directed to other UEs in the cell and estimates the load on the control plane. When the estimated load is above a threshold, the UE 110 delays the process of exiting the non-connected mode. Therefore, UE 110 defers sending signaling messages on control plane 414 (which are required for UE 110 to exit non-connected mode) to avoid exacerbating a possible overload condition on control plane 414.

[0059] Fig.101 is a block diagram of a UE 110 in an illustrative embodiment. The UE 110 includes a radio interface component 1002, one or more processors 1004, a memory 1006, a user interface component 1008, and a battery 1010. The radio interface component 1002 is a hardware component representing the local radio resources of the UE 110, such as an RF unit 1020 (e.g., a transceiver) and one or more antennas 1022, which is used to wirelessly communicate with a base station (e.g., base station 124) via radio or "over-the-air" signals. The processor 1004 represents the internal circuitry, logic, hardware, software, etc. that provides the functionality of the UE 110. The processor 1004 can be configured to execute instructions 1040 for software loaded into the memory 1006. The processor 1004 can include a set of one or more processors, or can include multiple processor cores, depending on the specific implementation. The memory 1006 is a computer-readable storage medium for data, instructions 1040, applications, etc., and is accessible by the processor 1004. The memory 1006 is a hardware storage device capable of storing information temporarily and / or permanently. The memory 1006 may include a random access memory or any other volatile or non-volatile storage device. The user interface component 1008 is a hardware component for interacting with an end user. For example, the user interface component 1008 may include a display 1050, a screen, a touch screen, etc. (e.g., a liquid crystal display (LCD), a light emitting diode (LED) display, etc.). The user interface component 1008 may include a keyboard or keypad 1052, a tracking device (e.g., a tracking ball or tracking pad), a speaker, a microphone, etc. The UE 110 may include Fig.10 Various other components not specifically shown.

[0060] The processor 1004 implements one or more applications 1030. These applications 1030 can access DL data through the RAN 120 and the core network 130, and can also generate UL data 1032 for transmission to a destination through the RAN 120 and the core network 130. The UL data 1032 can be buffered or queued by the application 1030 in the processor 1004, in the memory 1006, etc. As described above, the UL data 1032 may include unattended or background data generated by the application 1030. Background data is data generated by the application 1030, even when the user is not actively using the application 1030 (i.e., even if the screen is dark). For example, the application 1030 can request updates, news feeds, weather information, etc. while running in the background. The UL data 1032 may include MTC data or other types of data.

[0061] The processor 1004 also implements a transmit controller 1034 that is configured to control transmission of the UL data 1032 (and other UL data) to the RAN 120. In this embodiment, the transmit controller 1034 implements a passive mode transition process 1036 when handling transmission of the UL data 1032 to the network. For example, when the UE 110 is in idle mode, the transmit controller 1034 may check the load on the control plane 414 before transitioning the UE 110 to connected mode to transmit the UL data 1032, as described in more detail below.

[0062] Fig.11 1 is a flow chart showing a method 1100 of processing data transmission from a UE 110 to a network in an illustrative embodiment. Fig.10 The steps of method 1100 are described with reference to UE 110 in FIG. 1 , but those skilled in the art will appreciate that method 1100 may be performed in other networks or architectures. In addition, the steps of the flowcharts described herein are not all inclusive and may include other steps not shown, and these steps may be performed in an alternative order.

[0063] For this embodiment, UE 110 is in a non-connected mode (eg, idle mode) and does not have an RRC connection with RAN 120 (see Figure 1 ). The transmission controller 1034 of the UE 110 identifies data 1032 buffered for one or more applications 1030 running on the UE 110 (step 1102). For example, the application 1030 may send a data transmission request to the transmission controller 1034 to transmit the data 1032 to the mobile network 100. The transmission controller 1034 performs a passive mode transition process 1036 to send the data 1032 to the mobile network 100. For the passive mode transition process 1036, the transmission controller 1034 monitors the control plane 414 before transitioning to the connected mode, such as within a certain time interval (e.g., one second). The transmission controller 1034 determines the number of other UEs that received a signaling message (or a UE connection initiation message) for transitioning from the non-connected mode to the connected mode on the control plane 414 within the time interval (step 1104). The signaling message may provide information about how many other UEs are present in the cell, and / or how many other UEs are also attempting to transition from the non-connected mode to the connected mode. Transmit controller 1034 estimates the load on control plane 414 based on the number of other UEs in transition (step 1106). Transmit controller 1034 may estimate the load on control plane 414 during the last time interval (e.g., one second). The estimated load on control plane 414 may represent the load on control plane processor 128 (see Figure 1) when processing signaling messages to transition the UE from non-connected mode to connected mode. The transmission controller 1034 can then use the estimated load on the control plane 414 to determine whether it is necessary to transition the UE 110 to connected mode in order to transmit the buffered data 1032 to the mobile network 100.

[0064] More specifically, when the load on the control plane 414 exceeds a threshold, the transmission controller 1034 postpones the transition of the UE 110 from the non-connected mode to the connected mode to delay the transmission of the data 1032 to the mobile network 100 over the radio interface 122 (step 1108). In other words, the transmission controller 1034 will delay initiating a random access procedure and an RRC connection establishment procedure in order to establish an RRC connection with the RAN 120. The transmission controller 1034 may postpone the transition of the UE 110 from the non-connected mode to the connected mode until a maximum delay (optional step 1110), which may be set by the network operator. For example, the transmission controller 1034 may postpone the transition for multiple time intervals (e.g., one, two, three, etc.) until the maximum delay.

[0065] The threshold used by the transmission controller 1034 can be set as needed. In one embodiment, the threshold can be a percentage of the average load on the control plane 414 over a longer time interval (i.e., longer than the last time interval set for monitoring). For example, the transmission controller 1034 can monitor over a one-second time interval to estimate the load on the control plane 414. The transmission controller 1034 can also monitor over a longer time interval (such as ten seconds) to determine the average load on the control plane 414 (e.g., the average number of UEs that transition to connected mode per second). The transmission controller 1034 can therefore identify the threshold as a percentage of the average load (e.g., 200%, 300%, 400%, etc.). For example, if it is found that the number of UEs that transitioned to connected mode in the last time interval exceeds 400% of the average number of UE connection initiations per second in the past ten seconds, the transmission controller 1034 makes the following decision: UE 110 should wait until at least the next time interval (i.e., delay at least one second) before exiting the non-connected mode.

[0066] When the load on the control plane 414 does not exceed the threshold, the transmission controller 1034 transitions the UE 110 from the non-connected mode to the connected mode (step 1112). To this end, the transmission controller 1034 initiates a random access procedure and an RRC connection establishment procedure to establish an RRC connection. The transmission controller 1034 then initiates the transmission of data 1032 from the UE 110 to the mobile network 100 over the radio interface 122 (step 1114).

[0067] There may be different ways to estimate the load on the control plane 414, some examples of which are described in Figure 12 to Figure 13 In one example, the transmission controller 1034 may monitor the paging channel to obtain the cell on which the UE 110 resides. As described above, if DL data of an idle UE is received, the core network 130 will buffer the data and request to reestablish a bearer connection with the UE by paging the cell in the tracking area of ​​the UE. Fig.12 As shown in method 1200, the transmission controller 1034 monitors the paging message to determine or count the number of other UEs identified in the paging message (step 1202), such as during a certain time interval. The paging message includes one or more paging records, and each paging record includes a UE identifier (e.g., S-TMSI) indicating the intended recipient of the paging message. Therefore, the transmission controller 1034 can also determine or count the number of UE identifiers in the paging message (i.e., the number of different UEs addressed in one or more paging messages). The transmission controller 1034 can extend its listening interval and monitor all paging occasions in order to monitor the paging channel in this manner, rather than just the paging occasions (i.e., offsets) of UE 110. The transmission controller 1034 can then estimate the load 414 on the control plane based on the number of other UEs indicated in the paging message (step 1204).

[0068] In another example, the transmission controller 1034 may monitor the random access message of the cell, such as on the DL-SCH. As described above, a UE in non-connected mode will initiate a random access procedure to transition to connected mode. Fig.13 As shown in method 1300 of , the transmission controller 1034 monitors the random access message to determine or count the number of other UEs that receive random access response messages (e.g., RAR or message 2 of the random access procedure) (step 1302), such as during a certain time interval. The transmission controller 1034 can thus count the number of different UEs addressed by the random access response message. The transmission controller 1034 can decode the random access response messages of all UEs (i.e., even if the UE 110 does not just perform a random access attempt). The transmission controller 1034 can then estimate the load on the control plane 414 based on the number of other UEs that receive the random access response message (step 1304).

[0069] Based on the passive mode transition process 1036, the UE 110 decides when to transition to the connected mode. Thus, a solution to the overload condition on the control plane 414 can be provided in the UE without any new messages from the mobile network 100. This can be beneficial because the solution does not need to be network-based. Also, in terms of being instructed when to transition to the connected mode, the UE 110 actively defers its transition to the connected mode, rather than becoming a slave of the mobile network 100.

[0070] Any of the various elements or modules shown in the figure or described herein can be implemented as hardware, software, firmware or some combination thereof. For example, an element can be implemented as dedicated hardware. The dedicated hardware element can be referred to as a "processor", "controller" or some similar term. When provided by a processor, the function can be provided by a single dedicated processor, a single shared processor or multiple individual processors, some of which can be shared by individual processors. In addition, the explicit use of the term "processor" or "controller" should not be interpreted as specifically referring to hardware capable of executing software, and can implicitly include but are not limited to digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC) or other circuit system, field programmable gate array (FPGA), read-only memory (ROM) for storing software, random access memory (RAM), non-volatile memory, logic or some other physical hardware component or module.

[0071] In addition, the element can be implemented as an instruction that is executable by a processor or computer to perform the function of the element. Some examples of instructions are software, program code, and firmware. The instruction is operable when it is executed by the processor to instruct the processor to perform the function of the element. The instruction can be stored on a storage device readable by the processor. Some examples of storage devices are digital or solid-state memory, magnetic storage media such as disks and tapes, hard drives, or optically readable digital data storage media.

[0072] As used in this application, the term "circuitry" may refer to one, more, or all of the following:

[0073] (a) pure hardware circuit implementation (such as implementation using only analog and / or digital circuit systems);

[0074] (b) a combination of hardware circuitry and software such as (where applicable):

[0075] (i) a combination of analog and / or digital hardware circuits and software / firmware; and

[0076] (ii) any portion of hardware processor(s) (including digital signal processor(s)), software and memory with software that work together to enable a device (such as a mobile phone or server) to perform various functions; and

[0077] (c) Hardware circuit(s) and / or processor(s), such as microprocessor(s) or portion(s) of microprocessor(s), that require software (e.g., firmware) to operate, but which may not be present when not required for operation.

[0078] This definition of circuitry applies to all uses of the term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware. For example, if applicable to a particular claim element, the term circuitry also covers a baseband integrated circuit or processor integrated circuit for a mobile device, or a similar integrated circuit in a server, cellular network device, or other computing or network device.

[0079] Although specific embodiments are described herein, the scope of the present disclosure is not limited to these specific embodiments.The scope of the present disclosure is defined by the following claims and any equivalents thereof.

Claims

1. A user equipment (UE) configured to communicate with a mobile network via a radio interface, the UE comprising: at least one processor; as well as at least one memory including computer program code executable by said processor; The processor is configured to cause the UE to: identifying data buffered for one or more applications running on the UE when the UE is in a non-connected mode; while in non-connected mode, determining a number of other UEs receiving a signaling message on a control plane for transitioning from non-connected mode to connected mode; estimating a load on the control plane based on the number of other UEs receiving a signaling message for transitioning from non-connected mode to connected mode; as well as When the load on the control plane exceeds a threshold, transition of the UE from a non-connected mode to a connected mode is postponed to delay transmission of the data from the UE to the mobile network over the radio interface.

2. The UE according to claim 1, wherein the processor is further configured to cause the UE to: When the load on the control plane does not exceed the threshold, transitioning the UE from a non-connected mode to a connected mode; and The transmission of the data from the UE to the mobile network over the wireless interface is initiated.

3. The UE according to claim 1, wherein: The data buffered for the application includes background data.

4. The UE according to claim 1, wherein: The data buffered for at least one of the applications comprises machine type communication (MTC) data.

5. The UE according to claim 1, wherein the processor is further configured to cause the UE to: Paging messages are monitored to determine the number of other UEs identified in the paging messages.

6. The UE according to claim 1, wherein the processor is further configured to cause the UE to: The random access message is monitored to determine the number of other UEs that receive random access response messages.

7. The UE according to claim 1, wherein: The processor is configured to cause the UE to determine the number of other UEs that receive a signaling message within a first time interval; and The threshold is a percentage of an average load on the control plane over a second time interval that is greater than the first time interval.

8. A method of operating a user equipment UE to communicate with a mobile network over a radio interface, the method comprising: identifying data buffered for one or more applications running on the UE when the UE is in a non-connected mode; When the UE is in non-connected mode, determining a number of other UEs receiving a signaling message for transitioning from non-connected mode to connected mode on a control plane; estimating a load on the control plane based on the number of other UEs receiving a signaling message for transitioning from non-connected mode to connected mode; as well as When the load on the control plane exceeds a threshold, transition of the UE from a non-connected mode to a connected mode is postponed to delay transmission of the data from the UE to the mobile network over the radio interface.

9. The method according to claim 8, further comprising: When the load on the control plane does not exceed the threshold, transitioning the UE from a non-connected mode to a connected mode; as well as The transmission of the data from the UE to the mobile network over the wireless interface is initiated.

10. The method according to claim 8, wherein: The data buffered for the application includes background data.

11. The method according to claim 8, wherein: The data buffered for at least one of the applications comprises machine type communication (MTC) data.

12. The method of claim 8, wherein determining the number of other UEs receiving a signaling message for transitioning from a non-connected mode to a connected mode on the control plane comprises: Paging messages are monitored to determine the number of other UEs identified in the paging messages.

13. The method of claim 8, wherein determining the number of the other UEs receiving a signaling message for transitioning from a non-connected mode to a connected mode on the control plane comprises: The random access message is monitored to determine the number of other UEs that receive random access response messages.

14. The method of claim 8, wherein: Determining the number of the other UEs that receive signaling messages on the control plane comprises determining the number of other UEs that receive signaling messages within a first time interval; and The threshold is a percentage of an average load on the control plane over a second time interval that is greater than the first time interval.

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