Adapt to mobile network

Abstract

The subject of the present invention is "Adapting a mobile network". Methods, nodes, computer programs, computer program products and mobile networks for adapting a mobile network are described. In such a method for adapting a mobile network, a terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection. The first access node controls data transmission for the terminal, and wherein the second access node assists data transmission for the terminal. The method comprises: determining whether the quality of at least one of the first and second connections is degraded, obtaining quality degradation information about the quality degradation of at least one of the first and second connections based on a determining step, and adapting the mobile network based on an obtaining step. Thereby, in the case where at least one of the first and second connections may have been degraded or failed, network adaptation in a simple, efficient and fast manner is enabled.

Description

Technical Field

[0001] The present disclosure relates to telecommunications and, in particular, to methods for adapting a mobile network. A node, a communication system, a computer program, and a computer program product are also described. Background Art

[0002] The present disclosure is described in the context of Long Term Evolution (LTE), i.e., Evolved Universal Terrestrial Radio Access Network (UMTS) mobile communication system (E-UTRAN). It should be understood that the problems and solutions described herein are equally applicable to wireless access networks and user equipment (UE) implementing other access technologies and standards. LTE is used as an example technology to which the embodiments can be applied, and therefore LTE is used in the specification specifically for understanding the problems and solutions to solve the problems.

[0003] For easy understanding, LTE mobility is described below.

[0004] Radio Resource Control (RRC) (3rd Generation Partnership Project (3GPP) Technical Specification (TS) 36.331, e.g., V10.8.5 (2013-01)) is the primary signaling protocol used for configuration, reconfiguration, and general connection handling in the LTE radio access network (E-UTRAN). RRC controls many functions, such as connection establishment, mobility, measurement, radio link failure, and connection recovery. These functions have relevance to the present disclosure, and are therefore described in some further detail below.

[0005] A UE in LTE can be in two RRC states: RRC_CONNECTED and RRC_IDLE. In the RRC_CONNECTED state, mobility is controlled by the network, i.e. the network decides when and to which cell the UE should be handed over, based on, e.g., measurements provided by the UE. The network, i.e. the LTE radio base stations (referred to as evolved node base stations (eNodeBs or eNBs, respectively) in E-UTRAN) configure various measurement events, thresholds, etc., based on which the UE then sends reports to the network, enabling the network to make smart decisions to hand over the UE to a stronger cell when the UE moves away from the current cell.

[0006] Figure 1 It is described that according to 3GPP TS 36.300, for example V11.4.0 (2013-01), Fig.10 .1.2.1.1-1 LTERRC switching process. Figure 11. An LTE RRC handover procedure is illustrated. In a mobile network 100, a UE 102 is connected to a source eNodeB 104 of an LTE radio access network, the source eNodeB 104 being controlled by a mobility management entity (MME) 106 of a packet switched domain of a core network. A target eNodeB 108 is controlled by the MME 106. The user equipment 102 exchanges data with a serving gateway 110 of the core network. During the handover, the user equipment 102 is handed over from the source eNodeB 102 to the target eNodeB 108 of the radio access network. The corresponding user data signaling is indicated by a dashed arrow. The L3 control signaling is indicated by a dash-dot arrow, and the L1 / L2 control signaling is indicated by a solid arrow. The source node 104 sends management control information to the user equipment 102 in a first step 1, and the user equipment 102 in turn sends a corresponding measurement report to the source eNodeB 104 in a step 2. Then, the source eNodeB 104 performs a handover decision in step 3 and sends a handover request to the target eNodeB 108 in step 4. After performing admission control in step 5, the target eNodeB 108 sends a handover request response to the source eNodeB 102 in step 6, and the source eNodeB 102 starts RRC connection reconfiguration towards the UE 100 in step 7.

[0007] Figure 2A simplified diagram of a portion of an LTE handover (HO) procedure related to the present disclosure is illustrated. It should be noted that the HO command is actually prepared in the target eNB, but the message is transmitted via the source eNB. That is, the UE sees that the message comes from the source eNB. The mobile network 200 includes a source eNodeB 204 and a target eNodeB 208. The UE 202 is connected to the source eNodeB 204. After a step 210 of sending a measurement configuration from the source eNodeB 204 to the user equipment 202, in a step 212, the user equipment 202 performs an A3 event, in which the signal strength or signal quality of the target eNodeB 208 may be detected to be better than the signal strength or signal quality of the source eNodeB 204, respectively, and in a step 214, the user equipment 202 reports a measurement report to the source eNodeB 204 accordingly. After the corresponding handover decision in step 216, the source eNodeB 204 sends a handover request to the target eNodeB 208 in step 218, and the target eNodeB 208 in turn sends a handover response to the source eNodeB 204 in step 220. The source eNodeB 204 then sends a handover command to the user equipment 202 in step 222, and the user equipment 202 performs a random access procedure in step 224, during which a dedicated preamble is submitted to the target eNodeB 208. In addition, further arrows 226-230 relate to the completion of the handover procedure. In step 226, an uplink (UL) grant and a tracking area (TA) may be sent from the target eNodeB 208 to the UE 202. In step 228, a HO confirmation may be sent from the UE 202 to the target eNodeB 208. In step 230, a release context may be sent from the target eNodeB 208 to the source eNodeB 204. Steps 210, 214, 216, 218, 220, 222, 224 correspond to Figure 1 Follow steps 1, 2, 3, 4, 6, 7, and 11 in the .

[0008] In RRC_IDLE, mobility is handled by UE-based cell selection, where a nomadic UE 102, 202 selects the "best" cell to camp on, e.g., based on various specified criteria and parameters broadcast in the cell. For example, various cells or frequency layers may be prioritized over other cells or frequency layers, such that the UE 102, 202 attempts to camp on a particular cell as long as the measured quality of a beacon or pilot in that cell is better than some other beacon or pilot received from other cells.

[0009] As mentioned above, the present disclosure focuses primarily on issues associated with network controlled mobility, i.e. for LTE UEs in RRC_CONNECTED state. Therefore, the issues associated with failed handover are described in more detail below.

[0010] In normal situations, and when an RRC_CONNECTED UE 102, 202 moves out of the coverage of a first cell (also referred to as a source cell), it should be handed over to a neighboring cell (also referred to as a target cell or a second cell) before losing the connection to the first cell. That is, it is desirable to maintain the connection throughout the handover with no or minimal interruption so that the end user is unaware of the ongoing handover. In order for this aspect to be successful, it is necessary that

[0011] - a measurement report indicating a need for mobility is transmitted by the UE 102, 202 and received by the source eNB 104, 204, and

[0012] - the source eNB 104, 204 has sufficient time to prepare for the handover to the target cell (by, among other things, requesting the handover from the target eNB 108, 208 controlling the target cell), and

[0013] - The UE 102, 202 receives a handover command message from the network as prepared by the target eNB 108, 208 controlling the target cell and sent to the UE 102, 202 via the source cell, see Figure 1 and Figure 2 .

[0014] In addition, and in order for the handover to succeed, the UE 102, 202 must eventually succeed in establishing a connection to the target cell, which in LTE requires a successful random access request in the target cell, and a subsequent HO complete message. Note that the specifications may differ slightly in the naming of the messages. This does not limit the applicability of the present disclosure. For example, in Figure 2 The handover command marked as HO command in step 222 corresponds to Figure 1 The RRC configuration of step 7 is reconfigured, and Figure 2 The handover confirmation message of step 228 corresponds to Figure 1 The RRC configuration reconfiguration of step 11 is completed.

[0015] Therefore, it is clear that in order for all of this to succeed, it is necessary to start the series of events leading to a successful handover sufficiently early so that the radio link to the first cell (on which this signaling occurs) does not deteriorate too much before the signaling is completed. If such degradation occurs before the handover signaling is completed in the source cell (i.e., the first cell), the handover is likely to fail. Such handover failures (HOFs) are obviously undesirable. Therefore, the current RRC specifications provide various triggers, timers, and thresholds in order to configure the measurements appropriately so that the need for a handover can be detected reliably and sufficiently early.

[0016] exist Figure 2 In step 212, an exemplary measurement report is triggered by a so-called A3 event, which in brief corresponds to the scenario where a neighboring cell is found to have a better offset than the current serving cell. It should be noted that there are multiple events that can trigger a report.

[0017] It may happen that the UE 102, 202 loses coverage to the cell to which the UE 102, 202 is currently connected. This may happen in the following situations: when the UE 102, 202 enters a fading trough, or a handover is required as described above, but the handover fails for one reason or another. This is especially true if the "handover area" is very short. By constantly monitoring the radio link quality on the physical layer, for example as described in 3GPP TS 36.300, such as V11.4.0 (2013-01), TS 36.331, such as V11.2.0 (2013-01), and TS36.133, such as V11.2.0 (2013-01), the UE 102, 202 itself can declare a radio link failure and automatically start the RRC re-establishment process. If the re-establishment is successful, which depends, among other things, on whether the selected cell and the eNB 104, 108, 204, 208 controlling the cell are ready to maintain the connection to the UE 102, 202, the connection between the UE 102, 202 and the eNB 104, 108, 204, 208 can be restored. Failure of the re-establishment means that the UE 102, 202 goes to RRC_IDLE and the connection is released. In order to continue the communication, a completely new RRC connection must then be requested and established.

[0018] In the following, the features are described: dual connectivity and RRC diversity.

[0019] Dual connectivity is a feature defined from the perspective of a UE, where the UE can receive and transmit with at least two different network points simultaneously. At least two network points can be connected to each other via a backhaul link, enabling the UE to communicate with one of the network points via another network point. Dual connectivity is one of the features being standardized within the umbrella work of small cell enhancement within 3GPP Release 12 (Rel-12).

[0020] Dual connectivity is defined for the case when multiple aggregation network points operate on the same or separate frequencies. Each network point that the UE is aggregating may define an independent cell or it may not define an independent cell. In this regard, from the perspective of the UE, the term "independent cell" may specifically indicate that each network point, and thus each cell, may represent a separate cell. In contrast, from the perspective of the UE, network points that do not define independent cells may be considered to be one and the same cell. It is also foreseen that, from the perspective of the UE, the UE may apply some form of time division multiplexing (TDM) scheme between the different network points that the UE is aggregating. This means that communications on the physical layer to and from different aggregation network points may not actually be simultaneous.

[0021] Dual connectivity as a feature shares many similarities with carrier aggregation and coordinated multi-point (CoMP). The main differentiating factor is that dual connectivity is designed with relaxed backhaul and less stringent requirements on synchronization requirements between network points in mind. This is in contrast to carrier aggregation and CoMP, where strict synchronization and low-latency backhaul are assumed between connected network points.

[0022] Examples of features that dual connectivity would allow in a network are:

[0023] -RRC diversity (e.g., handover (HO) commands from the source and / or target); in this regard, the term "RRC diversity" may specifically indicate a scenario in which control signaling may be transmitted via at least two connections between the network and the UE;

[0024] - Radio Link Failure (RLF) robustness (fails only if both links fail);

[0025] - Decoupled uplink (UL) / downlink (DL) (e.g. UL to a low power node (LPN) with LPD corresponding to a small or pico cell, DL from a macro cell);

[0026] - Aggregation of macro anchor carrier and LPN data enhancement node(s);

[0027] - Selective switching (e.g., data to and from multiple nodes);

[0028] - Mobility between small cells hidden in the core network (CN) with C-plane in the macro cell; and

[0029] - Network sharing (operators may wish to always have the control plane and Voice over IP (VoIP) terminated in their own macros, but may be willing to offload best effort traffic to a shared network).

[0030] Figure 3 The dual connectivity feature of the UE 302 to the anchor 304a and the booster node 304b is illustrated.

[0031] A UE 302 in dual connectivity maintains concurrent connections 334a, 334b ​​to the anchor and booster nodes 304a, 304b. As the name implies, the anchor node 304a terminates the control plane connection towards the UE 302 and is therefore the control node for the UE 302. The UE 302 also reads system information from the anchor 304a. Figure 3 , system information and its spatial availability are indicated by dashed circles. In addition to the anchor 304a, the UE 203 may be connected to one or several enhancement nodes 304b for additional user plane support. In this regard, the term "enhancement" may mean that the performance of the UE may be improved in terms of the data packet rate of the UE, since user plane data may additionally be transmitted via the enhancement node. For this purpose, the transmission frequency used by the anchor may be different from the transmission frequency used by the enhancement node.

[0032] The roles of anchor and booster nodes are defined from the perspective of the UE 302. This means that a node acting as an anchor 304a to one UE 320 may act as a booster node 304b to another UE 302. Similarly, while the UE 302 reads system information from the anchor node 304a, a node acting as a booster node 304b to one UE 302 may or may not distribute system information to another UE 302.

[0033] Figure 4 The control plane and user plane termination in the anchor node or enhanced node is illustrated. This protocol architecture may represent an exemplary protocol termination that complies with dual connectivity and RRC diversity. Figure 4The protocol architecture shown in is proposed as a way forward for achieving dual connectivity in LTE Rel-12 in deployments with relaxed backhaul requirements. In the user plane 434, a distributed packet data convergence protocol (PDCP) / radio link control (RLC) approach is adopted, where the enhanced nodes and anchors terminate the user planes 436 of their respective bearers, with the possibility of achieving user plane convergence via the multipath transmission control protocol (MPTCP), which can provide split services to several connections. In the control plane 434, RRC and packet data convergence protocol (PDCP) are centralized at the anchor, with the possibility of routing RRC messages via the anchor, the enhanced node, or even on both links simultaneously. For completeness, "NAS" may represent the non-access stratum protocol layer, "RLC" may represent the radio resource control protocol layer, "MAC" may represent the medium access control protocol layer, and "PHYS" may represent the physical layer.

[0034] In another exemplary protocol termination that enables dual connectivity and RRC diversity, RRC is terminated in the anchor node and PDCP is available for both the anchor node and the enhanced node.

[0035] However, the problems described below may occur.

[0036] The problem may be related to handover failure and radio link failure for the scenario where the UE is connected to one network point (thus one cell).In the following, handover and radio link failure robustness is described.

[0037] The recent and rapid adoption of mobile broadband has led to a need to increase the capacity of cellular networks. One solution for achieving such capacity increase is to use a dense network consisting of several layers of cells with different "sizes": macro cells ensure large coverage, where the cells encompass large areas, while micro-, pico- and even femto-cells are deployed in hotspot areas where there is a large demand for capacity. Those cells typically provide connectivity in a much smaller area, but by adding additional cells (and the radio base stations that control those cells), the capacity increases as the new cells offload the macro cells.

[0038] Figure 5 UE 502 is illustrated moving out of the picocell area of ​​picocell 538 into the macrocell area of ​​macrocell 540. The direction of movement of user equipment 502 is indicated by arrow 542. This figure may illustrate a typical scenario for a handover of UE 502.

[0039] Cells of different "layers" may be deployed on the same carrier (i.e., a reuse-1 pattern where all neighboring cells may use the same frequency), small cells may be deployed on different carriers, and even different cells on various layers may be deployed using different technologies (e.g., 3G / High Speed ​​Packet Access (HSPA) on macro- and micro-layers, and LTE on the pico layer, as a non-exclusive example). In this regard, the term "layer" may specifically indicate a higher level of abstraction of a cell relative to the transmission frequency or carrier used in the cell.

[0040] There is currently a great deal of interest in studying the possibilities for such heterogeneous networks, and operators are interested in such deployments. However, it has also been found that, as briefly discussed above, such heterogeneous networks may result in increased handover failure rates. One reason is that the handover region in a heterogeneous network may be very short, meaning that a handover may fail because the UE loses coverage to the source cell before completing the handover to the target cell. For example, when a UE leaves a pico cell, it may happen that the coverage boundary of the pico cell is so sharp that the UE fails to receive any handover commands to the macro before losing coverage to the pico cell, see Figure 5 or Figure 6 .

[0041] Figure 6 The handover region of a pico / macro cell change to a macro / macro cell change is illustrated. The network includes a pico cell 638, a macro cell 640a, and another macro cell 640b. The abscissa 644 of the graph may represent reference signal received power (RSRP), and the ordinate 646 of the graph may represent distance. Curve 666 may represent RSRP perceived by a UE from a macro cell 640a, curve 668 may correspond to RSRP perceived by a UE from a pico cell 638, and curve 670 may represent RSRP perceived by a UE from another macro cell 640b. The handover region from a macro cell 640a to a pico cell 638 and vice versa is small compared to a handover region 674 between macro cells 640a, 640b.

[0042] Similar problems may arise when a UE connected to a macro cell suddenly enters a pico cell on the same carrier: it may now happen that the control channels of the pico cell interfere with the signal that the UE needs to receive from the macro cell in order to complete the handover, and thus the handover fails.

[0043] To investigate the consequences of increased handover identification and solutions for mitigating those consequences, 3GPP is currently working on evaluation and technical solutions for amendments, as described in TR 36.839, eg, V11.1.0 (2013-01).

[0044] In the following, key performance indicator (KPI) degradation and the need for drive testing are described. In this regard, the term "key performance indicator" may specifically refer to information collected by a network, which information may be related to performance characteristics of the network so that a corresponding managing network operator can adapt the network accordingly. For example, a KPI may be related to handover failures and may indicate information such as how often a handover may occur, in which area a handover may occur, the reason for the handover to occur, etc. The term "drive testing" may specifically refer to a process in which a dedicated test device, such as a user equipment, may move through a network, such as may travel in a vicinity, and network characteristics related to, for example, connectivity may be tested. In one option, an entity, such as software, may be spatially fixedly installed in a network and corresponding information may be collected from user equipment in the network.

[0045] Today, it is very difficult to determine whether a KPI problem experienced at a certain location in a radio network is due to a cell not receiving a UE transmission or a UE not receiving a cell transmission or both. The current typical approach to troubleshooting is to perform a drive test and collect both a cell trace with time stamped events / transmissions and a UE trace with events / transmissions collected from the UE used for the drive test. Here, the term "trace" may refer to a collection of log information.

[0046] In 3GPP, efforts have been made to support: when experiencing connection problems or problems in the access system, the UE collects some information, and then when connectivity to the network (NW) is established, at a subsequent time when the connection is established, the NW can ask the UE to transmit the collected information. The collected information has timestamp information based on the UE's internal clock and also location information.

[0047] Drive testing and using a specific UE for the drive test may not always be able to find intermittent failures or get into the location where the problem actually occurs. If it is a specific problem of the UE vendor, the UE used for the drive test may not have the same kind of failures as some of the UEs used by users in the network. Not only that, conventional drive testing is typically very expensive. There are a lot of costs for collecting data and there are also costs when analyzing the data. Since the drive tester needs to collect all the data on a fairly detailed level and hopes that intermittent failures occur and are captured in the data collected during the drive test in the large amount of data collected, data analysis may be costly and difficult.

[0048] Assuming a system where a UE is able to connect to several cells simultaneously, it is currently unclear how the UE should assess radio link failures and how the system should react in the event of these radio link failures or other connectivity issues with some of the maintained connections.

[0049] Furthermore, the evaluation of KPIs by the radio network for UEs experiencing radio link problems that are in certain locations at a certain time is problematic due to the degraded connectivity to the UE in these cases. Using current systems, the evaluation cannot be made immediately after a failure and is typically based on reports or (costly) drive tests. Therefore, direct adaptation of the system that could improve the KPIs is not possible. Summary of the invention

[0050] The object of the present invention is to provide measures with which a network adaptation of a mobile network in the event of a degradation in the quality of a connection in two connections between an access node of the mobile network and a terminal can be enabled in an improved manner. A further object of the present invention is to provide corresponding methods, terminals, nodes, mobile networks, computer programs, and computer program products.

[0051] The above objects are solved by a method, a terminal, a node, a mobile network, a computer program and a computer program product according to the independent claims.

[0052] According to a first exemplary aspect, a method for adapting a mobile network is provided. A terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection. The first access node controls data transmission of the terminal, and the second access node assists data transmission of the terminal. The method comprises: determining whether the quality of at least one of the first connection and the second connection is degraded, acquiring quality degradation information about the quality degradation of at least one of the first connection and the second connection based on a determining step, and adapting the mobile network based on the acquiring step.

[0053] According to a second exemplary aspect, a method for adapting a mobile network is provided. A terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection. The first access node controls data transmission of the terminal, and the second access node assists data transmission of the terminal. The method is performed by the terminal and includes: determining whether the quality of at least one of the first connection and the second connection is degraded, and obtaining quality degradation information about the quality degradation of at least one of the first connection and the second connection based on the determination step for specific use in adapting the mobile network.

[0054] According to a third exemplary aspect, a method for adapting a mobile network is provided. A terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection. The first access node controls data transmission of the terminal, and the second access node assists data transmission of the terminal. The method is performed by the first access node and includes: obtaining quality degradation information about quality degradation of at least one of the first connection and the second connection, and adapting the mobile network based on the obtaining step.

[0055] According to a fourth exemplary aspect, a method for adapting a mobile network is provided. A terminal is connected to a first access node of a mobile network via a first connection and to a second access node via a second connection. The first access node controls data transmission of the terminal, and the second access node assists data transmission of the terminal. The method is performed by the second access node and includes: adapting the mobile network based on the quality of at least one of the first connection and the second connection being degraded.

[0056] According to a fifth exemplary aspect, a terminal for adapting a mobile network is provided. The terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection. The first access node controls data transmission of the terminal, and the second access node assists data transmission of the terminal. The terminal comprises: a determination unit adapted to determine whether the quality of at least one of the first connection and the second connection is degraded, and an acquisition unit adapted to acquire quality degradation information about the quality degradation of at least one of the first connection and the second connection based on the determination for specific use in adapting the mobile network.

[0057] According to a sixth exemplary aspect, there is provided an access node for adapting a mobile network. A terminal is connected to the access node of the mobile network via a connection and to another access node via another second connection. The access node controls data transmission of the terminal, and the other access node assists data transmission of the terminal. The access node comprises: an acquisition unit adapted to acquire quality degradation information about quality degradation of at least one of the first connection and the second connection, and an adaptation unit adapted to adapt the mobile network based on the acquired quality degradation information.

[0058] According to a seventh exemplary aspect, there is provided an access node for adapting a mobile network. A terminal is connected to the access node of the mobile network via a connection and to another access node via another connection. The other access node controls data transmission of the terminal, and the access node assists data transmission of the terminal. The access node comprises: an adaptation unit adapted to adapt the mobile network based on the quality of at least one of the connection and the other connection being degraded, in particular, after the quality of at least one of the connection and the other connection is degraded.

[0059] According to an eighth exemplary aspect, a mobile network is provided. The mobile network comprises a terminal according to the fifth exemplary aspect, a first access node according to the sixth exemplary aspect, and a second access node according to the seventh exemplary aspect.

[0060] According to a ninth exemplary aspect, a computer program is provided. When the computer program is executed by a processor, the computer program is adapted to implement or control a method for adapting a mobile network according to any one of the first, second, third or fourth exemplary aspects.

[0061] According to a tenth exemplary aspect, a computer program product is provided, wherein the computer program product comprises a program code executed by at least one processor, thereby causing the at least one processor to execute a method according to any one of the first, second, third or fourth exemplary aspects.

[0062] The above and other objects, features and advantages will become more apparent in the following detailed description of the present disclosure as illustrated in the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 is a flow chart illustrating the signaling exchange for a handover procedure.

[0064] Figure 2 is a flow chart illustrating the signaling exchange for a handover procedure.

[0065] Figure 3 is a block diagram illustrating a mobile network used in conjunction with dual connectivity of a terminal.

[0066] Figure 4 is a schematic diagram illustrating a control plane and a user plane terminating in an access node.

[0067] Figure 5 is a block diagram illustrating an LTE mobile network.

[0068] Figure 6 is a schematic diagram illustrating the signal strength of an LTE mobile network depending on distance.

[0069] Figure 7 is a flow chart illustrating a method for adapting a mobile network according to an embodiment.

[0070] Figure 8 is a flow chart illustrating a method for adapting a mobile network according to another embodiment.

[0071] Fig. 9 is a flow chart illustrating a method for adapting a mobile network according to another embodiment.

[0072] Fig.10 is a block diagram illustrating a terminal for adapting a mobile network according to an embodiment.

[0073] Fig.11 is a block diagram illustrating an access node for adapting a mobile network according to an embodiment.

[0074] Fig.12 is a block diagram illustrating an access node for adapting a mobile network according to another embodiment. DETAILED DESCRIPTION

[0075] According to an exemplary aspect, in data transmission of a terminal, data may be transmitted from a first access node to the terminal via a first connection, and a copy of the data may be sent from a second access node to the terminal via a second connection. Here, the term "data transmission" may be related to the transmission of signaling data and / or payload data in an uplink direction from the terminal to the mobile network and / or in a downlink direction from the mobile network to the terminal. In order to enable the terminal to receive copy data from the first access node and the second access node, the first access node may have copied the corresponding data, and may have sent a copy of the data to the second access node via a backhaul connection between the first access node and the second access node. The first connection and the second connection may be independent of each other, and may include corresponding radio bearers established in connection with data transmission.

[0076] In such a communication scenario, a first access node may control the data transmission of a terminal, and a second access node may assist the data transmission of the terminal. In this regard, the term "a first access node controlling the data transmission of a terminal" may particularly indicate that the first access node controls the resource allocation of the uplink and / or downlink data transmission of the terminal and / or the connectivity state of the terminal. Therefore, the first access node may also be referred to as an anchor node for the data transmission of the terminal, for example, always used for the data transmission of the terminal. In LTE, such a communication scenario may be completed by terminating in the first access node a protocol related to resource allocation via the air interface between the terminal and the first access node, particularly the RRC protocol. Alternatively, the PDCP protocol may be terminated in the first access node. In particular, the term "a second access node assisting the data transmission of the terminal" may specifically indicate that the second access node may not have the ability to control the data transmission to the terminal, but may relay the uplink and / or downlink data transmission between the access node and the terminal. In particular, the second access node may be referred to as an enhanced node for the data transmission of the terminal, for example, as a relay node for the data transmission of the terminal. Therefore, as explained above, information transmitted between the first access node and the terminal may be transmitted in duplicate between the first access node and the terminal via the second access node.

[0077] In the communication scenario, at least one of the first connection and the second connection may include degraded quality. In order to perform appropriate mobile network adaptation in the event of such quality degradation, the quality of the first connection and / or the second connection may be determined, corresponding quality degradation information indicating that the quality of the first connection and / or the second connection may be degraded may be obtained based on the determining step, and based on the obtaining step, the mobile network may be adapted. In this regard, the term "obtaining information" may relate to an entity that obtains information by means of internally determining the information and / or by means of receiving the information through the mobile network.

[0078] Hence, connectivity degradation of connectivity between the terminal and the first access node and / or the second access node may be handled in an efficient, simple and fast manner.

[0079] Referring to the embodiments explained in the present disclosure, in the described embodiments, the first access node may be referred to as a "source eNB" and the first connection may refer to a Figure 3 In the described embodiments, the second access node may be referred to as an "assisting eNB" and the second connection may refer to an "anchor" connection 332a. Figure 3 The "enhanced" connection 332b in the . Note that, depending on whether it is a transmission control access node, the combination Figure 1 and Figure 2The target eNB 108, 208 described above may also represent an access node suitable for controlling data transmission of the terminal.

[0080] Next, embodiments related to the method according to the first exemplary aspect will be described. These embodiments also apply to the methods according to the second, third and fourth exemplary aspects, the terminal according to the fifth exemplary aspect, the first access node according to the sixth exemplary aspect, the second access node according to the seventh exemplary aspect, the mobile network according to the eighth exemplary aspect, the computer program according to the ninth exemplary aspect and the computer program product according to the tenth exemplary aspect.

[0081] The step of adapting the mobile network may comprise adapting at least one connection between the terminal and the mobile network based on the determining step. In particular, the terminal may be part of a mobile network.

[0082] Regarding the adapting step, in one variation of the method, the result of the determining step may be that the first connection comprises degraded quality, and the adapting step may comprise maintaining a connection that does not comprise degraded quality. In this case, the connection that does not comprise degraded quality may be the second connection.

[0083] Alternatively or in addition, the result of the determining step may be that the first connection includes degraded quality, and the adapting step may include: the first access node causes the terminal to be switched from the first access node to the second access node, and the first connection is disconnected. For example, the first access node may initiate the handover of the terminal by sending a handover request to the second access node. The second access node may then forward or relay the handover request to the terminal. The first access node may stop controlling the data transmission of the terminal. In LTE, the steps subsequently performed may be related to stopping RRC diversity. In this regard, the RRC diversity used in the first access node may be related to sending data directly to the terminal and to sending a copy of the data, which may be sent by the first access node to the terminal, to a second access node for forwarding a copy of the data to the terminal by the second access node. The data may include control signaling. Therefore, stopping RRC diversity may refer to no longer duplicating the data sent, thereby maintaining only a direct connection to the terminal to maintain conventional functions. This conventional connection may be switched to the second access node. Or in other words, particularly with respect to LTE, the latter may be related to stopping RRC signaling duplication and forwarding to the second access node. In the above case, the first access node may control the disconnection of the terminal, for example, by sending an RRC reconfiguration request message to the terminal via the second control node. In the above case, the adaptation step may also include: the first access node transfers the control capability for controlling the data transmission of the terminal from the first access node to the second access node. For example, a signaling bearer between the first access node and the terminal may be transferred to the second access node, and the bearer may transmit control signaling. In particular, reference may be made to Fig. 9 Steps 8, 9, 11 and the resulting step or state 999 are used to describe the later mentioned embodiments.

[0084] In a further variant of the method, the result of the determining step may be that the second connection comprises degraded quality, and the adapting step comprises: requesting, by the first access node, that the second connection be disconnected, and ceasing to use the second access node for data transmission of the terminal. In particular, the step of ceasing to use the second access node for data transmission may comprise: ceasing to copy data sent from the first access node to the terminal and ceasing to send the copied data to the second access node. In particular, this step may be embodied as stopping RRC diversity, involving no longer copying data or messages that may be sent to the second access node. The message associated with the disconnection request may be embodied as reference Figure 8 The stop RRC relay message explained in the preceding paragraphs may be used to stop the RRC relay message. Therefore, only a direct connection from the first access node to the UE may be maintained. Figure 8 This embodiment is described next.

[0085] Regarding the acquisition step, in a first variation of the method, the result of the determination step may be that one of the first connection and the second connection includes degraded quality, and the acquisition step may include: the terminal sending the quality degradation information to an access node in the first access node and the second access node, the connection of the access node to the terminal may not include degraded quality. In this case, the quality degradation information may be sent via the connection that does not include degraded quality. For example, as referred to Figure 8 As explained above, if the second connection may have failed, quality degradation information may be sent to the first access node. Fig. 9 To explain, if the first connection may have failed, quality degradation information may be sent to the second access node and relayed or forwarded by the second access node to the first access node.

[0086] In another variant, the result of the determining step may be that one of the first connection and the second connection includes degraded quality, and the obtaining step may include: sending quality degradation information by the terminal to an access node in the first access node and the second access node, the connection of the access node to the terminal may include degraded quality. In this case, the quality degradation information may be sent via a connection including degraded quality, and / or the quality degradation information may be sent via another connection between the terminal and the access node. The other connection may be different from the first connection and the second connection. This measure may advantageously enable: the terminal may inform the access node that the connection of the access node with the terminal has been identified as degraded in the direction from the access node to the terminal without involving other access nodes. Then, the access node may initiate adaptation of the mobile network without unnecessary delays. For this measure, it can be assumed that the connection in the transmission direction from the terminal to the access node may include sufficiently high quality for successfully transmitting the quality degradation information.

[0087] A connection including degraded quality may have failed. In this case, the quality degradation information may include or may be embodied as a failure notification indication, in particular, an RLF warning indication. The failure notification indication may represent an individual indication, in particular included in a conventional message or included in a new type of message, or may be a message of a specific type.

[0088] The quality degradation information may include or may be embodied as at least one of the following types of information. The information according to the first option may include or may be embodied as a cell identification indication indicating an area served by the access node associated with the failed connection, in particular an identification of a cell, in particular a PCell identification (ID), a cell global ID, a physical cell ID, or a carrier frequency of a cell. The information according to the second option may include or may be embodied as information about measurement results obtained for an area served by the access node associated with the failed connection and obtained for a previous time period. The information according to the third option may include or may be embodied as information about measurement results obtained for an area served by an access node associated with a non-failed connection, in particular a cell, and obtained for a previous time period. The information according to the fourth option may include or may be embodied as information about measurement results obtained for at least one additional area served by another access node different from the first access node and the second access node, in particular an additional cell, and obtained for a previous time period, in particular an identifier of the measurement. The information according to the fifth option may include or may be embodied as a connection indication indicating a failed connection. The information according to the sixth option may include or may be embodied as a failure timer of a failed connection. The information according to the seventh option may include or may be specified as a reason for the failure.

[0089] In such cases, the failure cause may include at least one of the following types of failure causes. In a first option, the failure cause may include the expiration of a timer, wherein the timer is started after a condition is satisfied for a predetermined number of counters and the timer is stopped after another condition is satisfied for a predetermined number of counters. For example, the latter may correspond to an "out-of-sync" failure in LTE, which may refer to the expiration of an RLF timer. Another failure cause may include that a maximum number of scheduling requests have been sent on the corresponding connection, in particular, without receiving a response. For example, in LTE, the latter may correspond to a scheduling request that has reached a maximum number. Another failure cause may include that a maximum number of data retransmissions have been sent by the terminal on the corresponding connection. For example, in LTE, the latter may correspond to a RLC retransmission that has reached a maximum number. In the case of RLC retransmissions, if no reply is received, the UE may retransmit the data until the maximum number of retransmissions can be reached. Another failure cause may include that a maximum number of unsuccessful random access attempts have been sent by the terminal on the corresponding connection, while no data transmission has been received on the corresponding connection. For example, in LTE, the latter may correspond to a random access channel (RACH) failure.

[0090] The at least one information mentioned above may be sent together with the failure notification indication in one message, or may be sent after the failure notification indication sent in the obtaining step.

[0091] Regarding the determining step, in a first variant of the method, the determining step may be performed by the terminal and may include evaluating the quality of the first connection and evaluating the quality of the second connection. In this case, the step of evaluating the quality of the first connection and the step of evaluating the quality of the second connection may be performed independently of each other. Additionally or alternatively, the respective evaluating step comprises: evaluating synchronization of the terminal with the respective access node with respect to data transmission on the respective connection. In particular, if the terminal may not be properly synchronized for data transmission on the respective connection, it may be determined that the quality of the respective connection is degraded. In particular, the determined degradation of the connection quality may correspond to a connection failure.

[0092] In a further variant of the method, the step of determining may comprise, in particular, for each of the first connection and the second connection, using a timer in the terminal and a counter in the terminal. The counter may be associated with the fulfillment of a condition, and if the timer may expire, a quality degradation of the respective connection may be determined, wherein the timer is started after a condition is fulfilled for a predetermined number of the counter, and the timer is stopped after another condition is fulfilled for a predetermined number of the counter. In particular, the timer may correspond to a T310 timer, and the counter may correspond to a constant N310. In particular, the same type or different types of timers and / or counters may be used for the first connection and the second connection.

[0093] In a further variant, the determining step comprises: in particular, for each of the first connection and the second connection, using a timer in the terminal and a plurality of counters in the terminal, each of the plurality of counters can be associated with the fulfillment of a condition, wherein if the timer can expire, a quality degradation of the respective connection can be determined, wherein the timer is started after a condition is fulfilled for a predetermined number of counters, and the timer is stopped after another condition is fulfilled for a predetermined number of another counter. In particular, the timer can correspond to a T310 timer, and the plurality of counters can correspond to counters or constants N310, N311. In particular, the same type or different types of timers and / or counters can be used for the first connection and the second connection.

[0094] With respect to the above-described embodiments, timer T310 and counters N310, 311 may represent a conventional timer and a conventional counter, respectively. Counter N310 may count conditional satisfactions in order to start timer T310. Such conditional satisfactions may be related to the following conditions: whether the signal to interference noise ratio (SINR) perceived by the terminal is below a threshold. Counter N311 may count conditional satisfactions in order to stop timer T310. Such conditional satisfactions may be related to the following conditions: whether the SINR perceived by the terminal may be above another threshold. Therefore, timer T310 may be started after counter N310 may have counted a predetermined number of conditional satisfactions of the condition associated with counter N310, and timer T310 may stop after having counted a predetermined number of conditional satisfactions of the condition associated with counter N311. If timer T310 may expire and may not have counted a predetermined number of conditional satisfactions of the condition associated with counter N311, degraded quality is detected.

[0095] The corresponding evaluation step described above may include: evaluating whether a maximum number of scheduling requests have been sent on the corresponding connection. Additionally or alternatively, the corresponding evaluation step may include: evaluating whether a maximum number of data retransmissions have been sent by the terminal on the corresponding connection. Additionally or alternatively, the corresponding evaluation step may include: evaluating whether a maximum number of unsuccessful random access requests have been sent by the terminal on the corresponding connection without receiving a data transmission on the corresponding connection.

[0096] A connection including degraded quality may not have failed.

[0097] In such a case, the result of the determining step may be that the first connection includes degraded quality and the second connection does not include degraded quality, and the adapting step may include switching the functionality of the first access node and the second access node with respect to controlling data transmission of the terminal. Thus, the first access node may become a transmission cooperating access node and the second access node may become a transmission controlling access node.

[0098] In this case, the quality degradation information may include or may be embodied as a channel quality indication, in particular, a channel quality indication report.

[0099] The obtaining step may include: sending quality degradation information by one of the first access node and the second access node to the other of the first access node and the second access node. For example, the determining step may be performed by the second access node, which may monitor a parameter associated with the channel quality information and / or may determine a value of the parameter.

[0100] Regarding the adapting step, in another variation of the method, the result of the determining step may be that the first connection and the second connection may have failed, and the adapting step may include establishing a further connection between the terminal and a further access node of the mobile network. According to this embodiment, the acquiring step may be performed by the terminal, and / or the establishing step may be initiated by the terminal. The further access node may be different from the first access node and the second access node, or may be one of the first access node and the second access node. Thus, the first connection and / or the second connection may be reestablished.

[0101] In particular, in the case mentioned later (where the result of the determining step may be that the first connection and the second connection have failed), the obtaining step may include: sending one or more connection failure reports, in particular, radio link failure reports, by the terminal to another access node of the mobile network. The one or more connection failure reports may include information about the first connection and / or the second connection and / or information about all connections of the terminal. The information may be related to the connection failure of a specific connection or multiple connections. For example, one connection failure report may be sent from the terminal, and information about the first connection and / or the second connection may be included in the one connection report. Alternatively, at least two connection failure reports may be sent by the terminal, and information about the connection failure of a specific multiple connection may be included in the at least two connection failure reports. The connection failure report may be sent after the terminal has successfully established a connection to another access node.

[0102] Regarding the acquisition step, in another variant of the method, the method may also include determining at least one key performance indicator of the mobile network, and the adaptation step may include adapting at least one system setting of the mobile network based on the at least one key performance indicator. Alternatively or in addition, the step of adaptation of the system settings may be based on the quality degradation information obtained, in particular, sent in the RLF indication or the RLF report. The goal of this adaptation may be an improvement of one of the key performance indicators in the network. In this regard, the system settings may be related to characteristics of the first access node and / or access node, or may be related to characteristics of another access node of the mobile network. The embodiments described above for adapting the mobile network may describe an immediate or self-organizing adaptation of the mobile network, and this embodiment related to the adaptation of the system settings may describe an overall adaptation of the mobile network over an intermediate or long-term time frame.

[0103] In particular, with regard to the network adaptation mentioned later, the determining step may be performed by the terminal and the obtaining step may be performed by the access node of the terminal and the first access node and the second access node. The method may include: obtaining, by the access node, further quality degradation information indicating that the quality of the connection between the terminal and the access node is degraded. The adaptation step may be performed based on the obtained quality degradation information and the determined further quality degradation information. The further quality degradation information may be related to: whether the maximum number of resynchronization attempts performed by the access node has been reached, whether the maximum number of scheduling requests sent by the access node has been reached, and / or whether the maximum number of RLC retransmissions by the access node has been reached. In order to correctly combine the quality degradation information and the further quality degradation information, each of the latter two types of information may be associated with a corresponding timestamp.

[0104] In such embodiments, the terminal may determine and send an RLF warning or CQI report to the access node. The access node may also determine the internal connection quality, and may then decide which network adaptation to perform with respect to the quality of the downlink and / or uplink direction of the connection being degraded. This adaptation may be related to the long-term adaptation described above.

[0105] Regarding the method according to the second exemplary aspect, the quality degradation information embodied as an RLF indication may be embodied as an RRC message or transmitted in an RRC message. Because the RRC may be terminated in the first access node, that is, the RRC message from the terminal to the second access node may always be terminated in the first access node. The quality degradation information embodied as a CQI report and sent to the second access node may not be automatically forwarded to the first access node, but as explained above, the second access node may be enabled to perform such steps. Therefore, the first access node may be enabled to perform an adaptation step based on the obtained quality degradation information.

[0106] With respect to the method according to the third exemplary aspect, the second access node may, in reference to Figure 8 In one option described later, the mobile network is adapted by stopping the RRC relay. Fig. 9 In another option described later, the second access node may obtain the RLF indication and may adapt the mobile network by upgrading to the first access node, and may optionally forward the RLF indication to the first access node. In a third option described later in conjunction with the CQI report, the second access node may receive the CQI report and may adapt the mobile network, and may optionally forward the CQI report to the first access node.

[0107] Refer to below Figures 7 to 12, further embodiments are described in more detail within the context of LTE. Note that throughout this application, the terms "terminal" and "user equipment" may be used in an interchangeable manner. One or more embodiments are based on the assumption that the UE is able to communicate independently via two maintained connections. In order to also provide radio link failure (RLF) diversity, the UE should trigger a standardized RLF procedure only if both links are out of sync. In this regard, the term "out of sync" may specifically mean that the user equipment may have lost synchronization with the access node because the user equipment may not be able to correctly decode synchronization information in terms of, for example, reference signals. However, if only one of the maintained connections fails, a different UE behavior must be implemented. Using the following embodiments, the UE is able to notify the involved eNBs of the RLF of one of the links by means of a new RRC RLF warning message, and the eNB is able to react quickly based on this information by stopping the RRC diversity connection and / or completely switching the UE to one of the involved eNBs. The eNB may also decide to move potential bearers mapped on the failed link to another link.

[0108] Figure 7 The steps of the method according to the embodiment are described. The relevant communication scenario includes: a user equipment UE, a first access node called a serving base station, and a second access node called an assisting base station. According to the first step 776, the user equipment is connected to the serving base station. This base station can request control signaling relay assistance from the assisting base station for the UE. In a further step 778, the UE is configured to transmit and receive control signaling via both the serving base station and the assisting base station, respectively, wherein the assisting base station relays the control signaling to and from the serving base station. In addition, the UE can monitor all maintained connected radio links respectively. In a further step 780, if the UE registers or detects that a radio link failure of one of the links has occurred, the UE can stop transmission on the link and can transmit a radio link failure warning indication to the serving base station via a second maintained link, possibly relayed by the assisting base station. In step 782 performed according to the first option of the method, if the failed link may be towards the assisting base station, the serving base station can issue to the UE to reconfigure to connect to the serving base station alone, and can issue to the assisting base station to stop assistance. Alternatively, in step 784 performed according to the second option of the method, if the failed link is towards the serving base station, the serving base station may stop transmission and the UE may be handed over to an assisting base station, which may become the UE's own serving base station.

[0109] Using the information obtained from the RLF-Warning of one link and the information from the other maintained connection, the E-UTRAN can quickly merge this information, learn the UE RLF failure reasons, their statistics and can apply necessary adaptations.

[0110] The embodiments are based on the assumption that the UE is able to communicate independently via two maintained connections, and in order to also provide radio link failure (RLF) diversity, the UE should only trigger the standardized RLF procedure when both links are out of sync. However, if only one of the maintained connections fails, different UE behavior must be implemented as explained below.

[0111] Hereinafter, the process according to the embodiment is described in more detail.

[0112] exist Figure 8 and Fig. 9 In the description, the signaling involved in the establishment of an RRC connection and in the reaction to RLF of one of the links is described. Figure 8 In FIG. 8 , a mobile network 800 includes: a user equipment 802, a source eNodeB 804, and an assisting eNodeB 808. Fig. 9 In FIG. 1 , a mobile network 900 includes a user equipment 902, a source eNodeB 904, and an assisting eNodeB 908. Figure 8 , 9 The RRC anchor functions of the source and target eNodeBs 804, 904, 908 are indicated by thick solid lines and are referenced by reference numerals 886, 986. Figure 8 , 9 , the RRC relay capabilities of the assisting eNodeBs 808 , 908 are indicated by thick dashed lines and referenced by reference numerals 888 , 988 .

[0113] according to Figure 8 , 9 In step 1, a measurement configuration is sent from the source eNodeB 804, 904 to the user equipment 802, 902. In step 2, an early measurement report is sent from the UE 802, 902 to the source eNodeB 804, 904. Figure 2804, 904. In the following step 3, an RRC assistance request is sent from the source eNodeB 804, 904 to the assisting eNodeB 808, 908. In the next step 4, an RRC assistance response containing RRC reconfiguration information is sent from the assisting eNodeB 808, 908 to the source eNodeB 804, 904. In the next step 5, RRC reconfiguration information is sent from the assisting eNodeB 808, 908 to the source eNodeB 804, 904. In step 5, RRC reconfiguration is sent from the source eNodeB 804, 904 to the UE 802, 902. In steps 890, 990, the source eNodeB 804, 904 starts RRC diversity. In steps 892, 982, the assisting eNodeB 808, 908 starts RRC relay. In the next step 6, the UE 802, 902 sends a synchronization and RACH procedure request to the assisting eNodeB 808, and the assisting eNodeB 808 sends a response to the UE 802, 902 accordingly.

[0114] Therefore, the UE 802, 902 is first configured with a measurement configuration (1) that issues an early measurement report (2). This measurement may be related to the source cell, the assisting cell, or a different cell. Upon receiving this measurement report in the source eNB 804, 904, it will (if required) request RRC diversity peering with the assisting eNB 808, 908 (3), the assisting eNB 808, 908 acknowledges this request (4) and contains the RRC-reconfiguration of the UE 802, 902 to set up RRC diversity transmission and reception, which the source eNB 804, 904 forwards to the UE 802, 902 (5). At this point, the source eNB 804, 904 will enter an RRC diversity state, in which RRC messages are transmitted to and received from the UE 802, 802, and additionally sent to and received from the assisting eNB 808, 908 for relaying to the UE 802, 902. The UE 802, 902 will initiate a RACH procedure towards the assisting eNB 808, 908 to synchronize with it (6).

[0115] exist Figure 8 The response process from RLF to assisting cells is described in Fig. 9 The process of RLF to source cell is described in.

[0116] In the following, the reaction to assisting eNB 808 being out of sync is described. Figure 8As described in step 884, RLF occurs between UE 802 and assisting eNodeB 808. In step 896, UE 802 stops transmitting to assisting eNodeB 808. In step 7, UE 802 alerts source eNodeB 804 of the occurrence of RLF, and source eNodeB 804 in turn stops RRC relay to assisting eNodeB 808 in step 8. In steps 898 and 899, source eNodeB 804 stops RRC diversity and assisting eNodeB 808 stops RRC relay, respectively. In steps 10 and 11, source eNodeB 804 sends an RRC reconfiguration request to UE 802, and UE 802 sends an RRC reconfiguration command to source eNodeB 804, respectively. UE 802 is connected to source eNodeB 804 in the communication until step 6. In the communication between the UE receiving the response and RACH procedure for synchronization in step 6 and the occurrence of step 11, dual connectivity is performed for UE 802, where source eNodeB 804 may represent an RRC anchor node. From step 11 onwards, UE 802 is connected to source eNodeB 804, but not to assisting eNodeB 808. Source eNB 804 may then send a path switch request to the core network node.

[0117] Therefore, as will be described below, after UE 802 has measured Layer 3 RLF towards the assisting cell (ie, timer T310 expires), Figure 8 ), it will stop transmission on this link, and trigger the transmission of (7) an RLF warning message towards the source eNodeB 804. The source eNodeB 804 will send an indication to the assisting eNB 808 to stop the RRC relay function for UE 802 (8), as it knows that UE 802 has triggered RLF to the assisting eNB 808. In this way, the assisting eNB 808 is immediately notified that the radio link to UE 802 has failed, which would not be possible using currently standardized solutions, where this state can only be estimated based on timers or the like. At this point, RRC diversity should be deactivated in both the source eNB 804 and the assisting eNB 808. The connection only between the source eNB 804 and the UE 802 should be maintained, so the UE 802 is configured to stop RRC diversity, but maintain the connection to the UE 802. The source eNB 804 uses the RRC reconfiguration procedure (10, 11) to reconfigure the UE 802 to leave the RRC diversity mode and connect only to the source cell.

[0118] Assuming the system has dual connectivity capability for UE 802, potential bearers terminated at cooperating eNB 808 will also be reconfigured to terminate at source eNB 804. To this end, source eNB 804 also sends a path switch command to the core network so that packets are routed to source eNB 804.

[0119] therefore, Figure 8 A radio link failure (RLF) warning is illustrated for assisting eNB 808 being out of synchronization.

[0120] In the following, the reaction to the source eNB 904 being out of sync is described. In step 994, RLF between the UE 902 and the source eNB 904 has occurred. In step 996, the UE 902 stops transmission to the source eNodeB 904. Subsequently, in step 7, an RLF warning is sent from the UE 902 to the source eNodeB 904 via the assisting eNodeB 908. In step 8, the source eNodeB 904 sends a handover request to the assisting eNodeB 908. In step 9, the assisting eNodeB 908 sends a handover acknowledgement to the source eNodeB 904. In step 11, the source eNodeB 904 sends an RRC reconfiguration request to the user equipment UE 902 via the assisting eNodeB 908. In step 998, the source eNodeB 904 stops RRC diversity, and in step 999, the assisting eNodeB 908 upgrades to the RRC anchor of the UE 902. In step 12, the source eNodeB 904 sends a sequence number status transfer to the assisting eNodeB 908, and in step 13, the UE 902 sends an RRC reconfiguration command to the assisting eNodeB 908. In step 14, the assisting eNodeB 908 sends a UE context release message to the source eNodeB 904. In the communication until the reception of synchronization and the reception of the RACH procedure related message by the UE 902, the UE 902 is connected to the source eNodeB 904. In the time interval between the UE 902 receiving the message in step 6 and the occurrence of the message transfer in step 13, dual connectivity for the UE 902 is performed, wherein the source eNodeB 904 is the RRC anchor node. From step 13 onwards, the UE 902 is connected to the assisting eNodeB 908.

[0121] Therefore, in Fig. 9, an RLF on the link to the source eNB 904 occurs and is registered in the UE 902. It will stop its transmission on this link and send an RLF warning indication (7) to the assisting eNB 908, which will (because it is in RRC relay mode) further forward this indication to the source eNB 904. The source eNB 904 will then completely handover the UE 902 to the assisting eNB 908, because it can be sure that the source 904-UE 902 connection is lost. Therefore, it will send a handover request indication (8) to the assisting eNB 908, which is answered by the assisting eNB 908 (9). The answer also contains a handover command for the UE 902, which the source eNB 904 should send to the UE 902. The source eNB 904 will send a handover command (RRC reconfiguration (11)) to the UE 902 via the RRC relay (i.e. the assisting eNB 908). Therefore, it is important that the assisting eNB 908 remains in RRC relay mode even though it has received and acknowledged the full handover from UE 902. After relaying the handover command to UE 902, the assisting eNB 908 is able to promote itself to the RRC anchor for UE 902. The source eNB 904 can stop RRC diversity. Now, both nodes 904, 908 will follow the standardized HO procedure, i.e., the source eNB 904 will send a sequence number status transfer (12) to the assisting eNB 908 and forward the buffered packets. The UE 902 will confirm the RRC reconfiguration to connect only to the assisting (now anchor) eNB 908 (13), and finally, the assisting eNB 908 will send a UE context release indication to the source eNB 904 (14).

[0122] In another embodiment, in the case where the source requests a full handover, the assisting eNB 908, which is in RRC relay mode for the UE 902, will transmit the handover command (11) to the UE 902 itself. In this variation, the handover request reply message does not need to contain the handover command for the UE 902, because the source eNB 904 should no longer transmit it. However, the source eNB 904 needs to be informed that the UE 902 is being handed over to the assisting eNB 908 and that the SN status transfer and buffered data transfer need to be initiated.

[0123] In another embodiment, the assisting eNB 908 may also check the RLF warning it forwards and send a handover response directly to the source eNB 904, and send a handover command to the UE 902 itself.

[0124] therefore, Fig. 9 A radio link failure (RLF) warning for source eNB desynchronization is illustrated.

[0125] Hereinafter, radio link failure related actions according to embodiments are described.

[0126] It is assumed that the current RLF procedure is only triggered if the conditions for RLF on all links are met simultaneously. Therefore, RRC needs to evaluate the physical layer problems of all links separately.

[0127] The timers and constants for the UE 802, 902 used to evaluate physical layer problems should be configurable on a per-link basis, so multiple instances of IErlf-TimersAndConstants (or at least a subset of certain timers / constants, e.g., T310, N310, N311) should exist and be configurable in the UE 902, 902. In another embodiment, the same value is applied to each link in the link, but still evaluated independently.

[0128] In the following, the RLF-TimersAndConstants information element for each maintained connection is described. In this information element, the above mentioned timers and constants may be included.

[0129] --ASN1START

[0130]

[0131]

[0132] In order to detect physical layer problems in RRC_CONNECTED, if N310i continuous "out of sync" indications are received from lower layers instead of T300 i, T301i, T304 i, T311 i and then timer T 310i is started, UE802, 902 evaluates each connected cell i separately. When N311 i continuous "in sync" indications are received from lower layers while T310i is running, UE should stop timer T310 i. If some more advanced techniques of "out of sync" / "in sync" evaluation are applied, such as additionally evaluating whether measurement reports are sent, separate evaluations based on each link should also be applied.

[0133] Hereinafter, a RLF warning procedure according to an embodiment is described.

[0134] When T310 of a certain cell expires, or the maximum number of scheduling requests is reached, or the RLC maximum number of retransmissions is indicated for this cell, the UE 802, 902 shall trigger a new RLF-Warning procedure as defined below.

[0135] The UE 802, 902 should trigger the following modified actions and prepare a RLF warning indication to be sent directly via the second maintained connection. In addition, a conventional RLF report is prepared in a modified manner.

[0136] The following two pseudo-random code examples may describe the RLF procedure according to TS 36.331 V11.2.0 (2012-12), section 5.3.11.3 "Detection of RLF" Figure 8 , 9 Method embodiment. For the sake of clarity, the pseudo-random code portion that has not been modified has been omitted. In particular, the derivation from this standard can be inferred by means of comparison with the pseudo-random code example and is presented in bold for the sake of visibility. The first pseudo-random code example may be related to a method embodiment, wherein the terminal 802, 902 can stop transmitting and receiving via a degraded or failed connection, and therefore can stop communication in both the uplink direction and the downlink direction. The second pseudo-random code example may be related to a method embodiment, wherein the terminal can continue to transmit in the uplink direction via a degraded or failed connection to the corresponding access node 804, 808, 904, 908, but may not receive any information via a degraded or failed connection toward the corresponding access node 804, 808, 904, 908.

[0137] Alternative 1:

[0138] 2> Detected radio link failures are not considered;

[0139] 2> Store the following radio link failure information in the modified VarRLF-Report according to the selection of the link for transmitting the RLF warning described below or according to the RLF warning content described below

[0140] 2> If AS security has not been activated: 3> On leaving RRC_CONNECTED as specified in 36.331 / 5.3.12 with a release cause of 'other', no action is performed;

[0141] 2> Otherwise:

[0142] 3> Do not initiate the connection re-establishment procedure as specified in 36.331 / 5.3.7;

[0143] 2> Stop transmission and reception on the link where RLF is detected;

[0144] 2> Triggering the transmission of a new RLF-Warning indication from the UE to E-UTRA via one or more of the other maintained connections

[0145] Alternative 2:

[0146] 2> Detected radio link failures are not considered;

[0147] 2> Store the following radio link failure information in the modified VarRLF-Report according to the RLF warning content described below

[0148] 2> If AS security has not been activated: 3> On leaving RRC_CONNECTED as specified in 36.331 / 5.3.12, where the release cause is 'other', no action is performed;

[0149] 2> Otherwise:

[0150] 3> Do not initiate the connection re-establishment procedure as specified in 36.331 / 5.3.7;

[0151] 2> Triggering the transmission of a new RLF-warning indication from the UE to the E-UTRA via one or more of the other maintained connections Using alternative solution 2, the terminal 802, 902 does not stop transmission / reception on the link where T310 has expired. The expiration of T310 only means that there is a problem with the downlink channel due to poor channel quality, but this does not mean that there is any problem in the uplink. Therefore, the uplink transmission can successfully reach the base station 804, 808, 904, 908. This is expected to be beneficial in particular in the following case: a response to the terminal uplink transmission can be transmitted from the network to the terminal 802, 902 on an alternative link, such as a link where RLF has not been detected.

[0152] If the terminal 802, 902 continues to transmit and receive (attempt to receive) on the link for which T310 has expired, it is possible that the terminal 802, 902 may resume use of the link if the link subsequently becomes better after RLF has been detected.

[0153] For example, the terminal 802, 902 may detect an RLF on a connection to one of the source access node 804, 904 and the assisting access node 808, 908, and in a first option, the terminal 802, 902 may send an RLF indication to the respective other access nodes 804, 808, 904, 908, which forward the RLF indication to the access node 804, 808, 904, 908 associated with the detected RLF. The terminal 802, 902 may stop transmission and / or reception to the access node 804, 808, 904, 908 associated with the detected RLF, or may continue transmission and / or reception with the access node 804, 808, 904, 908 associated with the detected RLF. In a second option, the terminal 802, 902 may send an RLF indication to the access node 804, 808, 904, 908 associated with the detected RLF. In this case, the terminal 802, 902 may not stop transmission and / or reception with this access node 804, 808, 904, 908. The access node 804, 808, 904, 908 may in turn forward the RLF warning to other access nodes 804, 808, 904, 908 that are not associated with the detected RLF.

[0154] In the following, selection of a link for transmitting an RLF warning according to an embodiment is described.

[0155] The terminal 802, 902 may select a set of configured links on which it sends RLF warnings. For example, it may send RLF warnings to all cells on a subset of all configured links, such as only on the source link.

[0156] If the terminal 802, 902 knows that it has one or more alternative links to the node 804, 808, 904, 908 that provides the link for which T310 has expired, for example if there are two links from the node to the terminal 802, 902 and T310 expires for only one of these links, it would be beneficial to transmit an RLF warning on the one or more alternative links.

[0157] The terminal 802, 902 may send an RLF warning even on a link where T310 has expired. The benefit of sending an RLF warning on a link where T310 has expired is that the relevant nodes 804, 808, 904, 908 may need to be informed of the expiration of T310. The expiration of T310 indicates that the downlink quality is poor, whereas the uplink may still have sufficiently good quality to allow the RLF warning to reach the relevant nodes 804, 808, 904, 908.

[0158] Hereinafter, RLF warning content according to an embodiment is described.

[0159] (1) This RLF Warning message indicates to E-UTRA that one of the maintained connections has been lost. It may optionally contain a subset of the information from the regular RLF report, as well as details of the cause of the failure. It may also contain an indicator of which connection the RLF Warning belongs to. A non-exclusive list of potential fields for the RLF Warning is given below. Information about the cell to which the RLF Warning belongs

[0160] -Primary cell (PCell) identification (ID), cell global ID, physical cell ID, carrier frequency of this cell

[0161] (2) The latest or historical measurement results of the cell to which the RLF warning belongs

[0162] - Reference Signal Received Power (RSRP), Reference Signal Received Quality (RSRQ), or other

[0163] (3) The latest or historical measurement results of other service cells

[0164] - RSRP, RSRQ, etc., corresponding measured cell identifier

[0165] (4) Latest or historical measurement results of non-serving neighboring cells

[0166] -E-UTRA, UMTS Terrestrial Radio Access (UTRA), Global System for Mobile Communications (GSM) Enhanced Data rates for GSM Evolution (EDGE) Radio Access Network (GERAN), CDMA2000, or other system measurements

[0167] (5) Failure time

[0168] (6) Detailed failure type and cause

[0169] -Asynchronous, reaching the maximum number of scheduling requests, RLF retransmissions, etc.

[0170] (7) UE status information, list of current events, such as measurement events.

[0171] (8) Buffer status

[0172] In the following, a modified RLF report according to an embodiment is described. This type of RLF report can be considered as modified relative to the conventional RLF report according to TS 36.331 V11.2.0 (2012-12), which can be an RLF report for a single connection between a terminal 802, 902 and an access node 804, 808, 904, 908.

[0173] In the original RLF report, the terminal 802, 902 stores the RLF related information for the (single) link where the failure occurred and sends the report to the E-UTRAN upon request. This report is overwritten when another RLF occurs. In RRC diversity, the terminal 802, 902 should trigger the original RLF procedure and the original RLF report only when all links fail. Therefore, this report can be modified to convey information about multiple links.

[0174] In one embodiment, a single modified RLF report may contain information about multiple or all links.

[0175] In another embodiment, multiple RLF reports, thus an RLF report for each link, may be created and requested by E-UTRA independently or collectively.

[0176] In the following, channel quality indication (CQI) monitoring in the network is described. The CQI information or report may represent an alternative embodiment of the quality degradation information with respect to the RFL warning indication described above.

[0177] As an alternative to using the RLF warning in the network to trigger the RRC reconfiguration of the UE 802, 902 as explained above, the CQI report received for each link in the respective network node 804, 808, 904, 908 may be forwarded to another node 804, 808, 904, 908, which is also currently connected to the UE 802, 902. For example, in the case where the source eNodeB 804, 904 may be associated with a degradation in the quality of the connection, the CQI received by the source eNodeB 804, 904 may be transmitted to the assisting eNodeB 808, 908. In the case where the assisting eNodeB 808, 908 may be associated with a degradation in the quality of the connection, the CQI received by the assisting eNodeB 804, 904 may be sent to the source eNodeB 804, 904. In one embodiment, the network will monitor the received CQI reports received from the terminal 802, 902 regarding the different connections of the terminal. If the reported CQI indicates that the channel quality of a connection is below a certain threshold, the network will consider the connection unsuitable for use by the terminal 802,902.

[0178] In case the network considers that the quality of the connection is not good enough and is not suitable for use by the terminal 802, 902, it may take actions such as the following. Note that different behaviors may apply depending on which type of connection is concerned.

[0179] (1) Triggering Handover - The network may command the terminal 802, 902 to perform a handover to another, possibly better quality, cell. If the connection with poor quality is the source cell, this is an alternative approach to ensure that another cell becomes the source connection. In the case where the assisting cell has been identified as having better quality than the source cell, a similar process such as that described above for the reaction to the source eNB being out of sync may be envisaged.

[0180] (2) Source cell and assisting cell switching - If the network detects that the quality of the source cell is below a certain threshold and the quality of the assisting cell is acceptable, the network can trigger a switch so that the assisting cell becomes the source cell instead, and the source cell is called the assisting cell instead. This is similar to handover, however it may not include RRC reconfiguration in the UE 802, 902, because the UE 802, 902 does not care about the network element 804, 808, 904, 908 acting as the RRC anchor.

[0181] (3) De-configuring the assisting cell - If the quality of the cell acting as the assisting cell is not good, the motivation is to keep the assisting cell. Therefore, the network can de-configure the assisting cell. In the case after de-configuring the assisting cell, the terminal 802, 902 is configured only by the source cell, which can de-configure the RRC diversity. This behavior is similar to the process described above for the reaction to the assisting eNB being out of sync.

[0182] Hereinafter, RLF warning for UL / DL troubleshooting in E-UTRAN according to an embodiment is described.

[0183] Whenever an RLF warning occurs for one link of the connection (e.g. triggered by a loss of synchronization, reaching a maximum number of scheduling requests, or reaching a maximum number of RLC retransmissions), the receiving eNB 804, 808, 904, 908 can use the information about the failure cause and UE measurements, etc., as given in the warning message by combining it with its own information about the working link (e.g., about current events and transmissions made for the UE). Thus, using the RLF warning procedure, the E-UTRAN is able to combine the UE and eNB information to determine whether the problem is related to the eNB 804, 808, 904, 908 not receiving the UE 802, 902 on the link where the problem was indicated or vice versa or both.

[0184] In addition, the eNB 804, 808, 904, 908 may experience similar failures as the UE 802, 902, such as reaching a maximum number of resynchronization attempts, reaching a maximum number of scheduling requests, or reaching a maximum number of RLC retransmissions, and then the eNB 804, 808, 904, 908 may ask the UE 802, 902 to provide historical data about UE events and transmissions made. This functionality can be established with another request / response message triggered by the eNB 804, 808, 904, 908 and transmitted via one of the maintained connections.

[0185] Using the combined information, the E-UTRAN is able to react quickly in the event of these connectivity issues and adapt its system settings to improve the performance of the UE 802, 902 and the entire system, such as certain key performance indicators.

[0186] Other embodiments are as follows:

[0187] In one embodiment, rather than relying on an existing T310 timer for the respective link to trigger the RLF warning transmission, a new timer for each link is used that is started at the same time as the T310 timer, but has a different expiration time. In this way, the RLF warning indication transmission can be triggered independently of the existing RLF evaluation for each link, so that, for example, the RLF warning can be transmitted earlier than RLF is triggered on the link. Furthermore, the second N310 and N311 constants for each link can be used for this evaluation.

[0188] In the following, advantages of one or more embodiments are described.

[0189] Using the provided solution, unnecessary transmissions between the UE 802, 902 and the eNB 804, 808, 904, 908 are avoided in the RRC diversity mode. In this way, interference and battery consumption are reduced. Using the discussed procedures, the UE 802, 902 is able to maintain the RRC connection when experiencing RLF on one link in the diversity transmission mode. A fast fallback (or fast fallback) to one of the maintained connections if one of the connections fails is ensured.

[0190] Furthermore, this solution will allow the operator to understand the root cause of gap performance degradation in the radio network and in particular understand whether it is a network problem or a UE problem or both. This method will also work in fairly poor conditions since only one of several connections to the network needs to work.

[0191] Using this solution, the system can adapt very quickly to UE connectivity issues and adapt the system to improve system performance.

[0192] Reference Fig.10 , describes a terminal 1002 for adapting a mobile network. For example, the terminal 1002 may correspond to the terminal 802 or 902. The terminal 1002 is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection. The first access node controls data transmission of the terminal 1002, and wherein the second access node assists the data transmission of the terminal 1002. The terminal 1002 may include one or more interfaces 1003 to the first access node and the second access node. The one or more interfaces 1003 may each be coupled to a processor 1005 of the terminal 1002, and the processor 1005 may access a memory 1007 of the terminal 1002.

[0193] The terminal 1002 includes: a determining unit 1009, which is adapted to determine whether the quality of at least one of the first connection and the second connection is degraded, and an obtaining unit 1011, which is adapted to obtain quality degradation information about the quality degradation of at least one of the first connection and the second connection based on the determination for adapting the mobile network based on the obtained quality degradation information. In another implementation, the terminal 1002 may include: a determining unit 1009, which is adapted to determine whether the quality of at least one of the first connection and the second connection may be degraded, and an obtaining unit 1011, which is adapted to obtain quality degradation information about the quality degradation of at least one of the first connection and the second connection based on the determination for specific use in adapting the mobile network.

[0194] In the above two described implementations, the determining unit 1009 may be a part of the processor 1005. In addition, the acquiring unit 1011 may be a part of the one or more interfaces 1003. The one or more interfaces 1003 may also include a receiving unit 1013 and a sending unit 1015 for respectively implementing the receiving capability and the sending capability of the one or more interfaces 1003. The sending unit 1015 may implement the above functions related to sending quality degradation information.

[0195] The terminal 1002 is suitable for executing the method according to the above embodiment and includes a Fig.10 The corresponding physical units 1003, 1005, 1007 described in the figure are units based on corresponding functions.

[0196] Reference Fig.11, an access node 1104 for adapting a mobile network is illustrated. For example, the access node 1104 may correspond to the first access node 804, 904. The terminal is connected to the access node 1104 of the mobile network via a connection and to another access node via another second connection. The access node 1104 controls data transmission of the terminal, and another access node assists data transmission of the terminal. The access node 1104 may include: one or more interfaces 1103 to the terminal and another access node. The one or more interfaces 1103 may each be coupled to a processor 1105 of the access node 1104, and the processor 1105 may access a memory 1107 of the access node 1104.

[0197] The access node 1104 includes: an acquisition unit 1111, which is adapted to acquire quality degradation information about the quality degradation of at least one of the first connection and the second connection based on the determination of whether the quality of at least one of the first connection and the second connection is degraded, and an adaptation unit 1117, which is adapted to adapt the mobile network based on the acquired quality degradation information. In another implementation, the access node 1104 may include: an acquisition unit 1111, which is adapted to acquire quality degradation information about the quality degradation of at least one of the first connection and the second connection. For example, the quality degradation information may be based on the determination that the quality of at least one of the first connection and the second connection may be degraded. In this other implementation, the access node 1104 may include: an adaptation unit 1117, which is adapted to adapt the mobile network based on the acquired quality degradation information. In both implementations, the access node 1104 may also include: a determination unit, which is adapted to determine whether the quality of at least one of the connection and the other connection may be degraded.

[0198] In the above two implementations, the acquisition unit 1111 and the adaptation unit 1117 may be part of the one or more interfaces 1103. The one or more interfaces 1103 may also include a receiving unit 1113 and a sending unit 1115 for respectively implementing the receiving capability and the sending capability of the one or more interfaces 1103. The determination unit may be part of the processor 1105.

[0199] The access node 1104 is adapted to perform the method according to the above-mentioned embodiment and comprises a Fig.11 The corresponding physical units 1103, 1105, and 1107 described in the figure are units based on corresponding functions.

[0200] Reference Fig.12, an access node 1208 for adapting a mobile network is illustrated. For example, the access node 1208 may correspond to the access nodes 808, 908. The terminal is connected to the access node 1208 of the mobile network via a connection and to another access node via another connection. The other access node controls data transmission of the terminal, and the access node 1208 assists the data transmission of the terminal. The access node 1208 may include: one or more interfaces 1103 to the terminal and another access node. The one or more interfaces 1203 may each be coupled to a processor 1205 of the access node 1208, and the processor 1205 may access the memory 1107 of the access node 1208.

[0201] The access node 1208 comprises: an adaptation unit 1217 adapted to adapt the mobile network based on the acquired quality degradation information about the quality degradation of at least one of the connection and the other connection, the acquisition of the quality degradation information being based on the determination of whether the quality of at least one of the connection and the other connection is degraded. In another implementation, the access node 1208 may comprise: an adaptation unit 1217 adapted to adapt the mobile network based on the quality of at least one of the connection and the other connection being degraded. In this implementation, the adaptation unit 1217 may be adapted to perform the adaptation based on the acquired quality degradation information about the quality degradation of at least one of the connection and the other connection. The acquisition of the quality degradation information may be based on the determination of whether the quality of at least one of the connection and the other connection is degraded.

[0202] In the latter two implementations, the access node 1208 may include: an acquisition unit 1211, which is adapted to acquire quality degradation information. In the latter two implementations, the access node 1208 may also include: a determination unit 1209, which is adapted to determine whether the quality of at least one of the connection and another connection is likely to be degraded.

[0203] The adapting unit 1217 may be part of the one or more interfaces 1203, and the acquiring unit 1111 may also be part of the one or more interfaces 1203. The one or more interfaces 1203 may also include a receiving unit 1213 and a sending unit 1215 for respectively implementing the receiving capability and the sending capability of the one or more interfaces 1203. The determining unit 1209 may be part of the processor 1205.

[0204] The access node 1208 is adapted to perform the method according to the above-mentioned embodiment and comprises a Fig.12 The corresponding functional units in the corresponding physical units 1203, 1205, and 1207 described in the figure.

[0205] It is noted that the described functional-based units 1009 to 1015, 1109 to 1117, 1209 to 1217 for implementing the above-described functionalities of the respective entities 1002, 1104, 1208 may also be implemented in software and / or in hardware and software. To this end, appropriately configured computer program codes for implementing the above-described functionalities of the respective entities 1002, 1104, 1208 may be stored in the memories 1007, 1107, 1207 of the respective aforementioned entities 1002, 1104, 1208. The memories 1007, 1107, 1207 and the computer program codes may form a computer program product. The computer program codes may also be stored in different memories that can be loaded into the memories 1007, 1107, 1207 of the respective entities 1002, 1104, 1208. The computer program codes may also be provided in a downloadable form, forming another computer program product.

[0206] Note that in Figures 10 to 12 The associations between the physical units 1003 to 1007, 1103 to 1107, 1203 to 1207 of the terminal 1002 and the access nodes 1104, 1208, respectively, and the function-based units 1009 to 1015, 1109 to 1117, 1209 to 1217 of the terminal 1002 and the access nodes 1104, 1204, respectively, illustrated in these figures, may be different from the described embodiments. Fig.10 The acquisition unit 1011 of the terminal 1002 described in the figure may be a part of the interface 1003 , the processor 1005 , and the memory 1007 of the terminal 1002 .

[0207] It is noted that the embodiments can be applied to radio access networks of LTE and GSM and UMTS.

[0208] Hereinafter, various additional embodiments of the present disclosure will be described.

[0209] 1. A method for adapting a mobile network, wherein a terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection, wherein the first access node controls data transmission of the terminal and the second access node assists data transmission of the terminal, the method comprising:

[0210] - determining whether the quality of at least one of the first connection and the second connection is degraded,

[0211] - obtaining quality degradation information about quality degradation of at least one of the first connection and the second connection based on the determining step, and

[0212] -Adapting the mobile network based on the acquisition step.

[0213] In particular, the terminal is part of a mobile network.

[0214] In particular, the term "the first access node controls the data transmission of the terminal" may in particular mean that the first access node controls the resource allocation for the uplink and / or downlink data transmission of the terminal and / or the connectivity state of the terminal. In particular, the first access node may be referred to as an anchor node for the data transmission of the terminal, for example, always used for the data transmission of the terminal. For example, in LTE, the control of the data transmission may include: in the first access node, terminating a protocol related to the resource allocation via the air interface between the terminal and the first access node, in particular the RRC protocol.

[0215] In particular, the term "the second access node assists the data transmission of the terminal" may particularly mean that the second access node may not have the ability to control the data transmission to the terminal, but may relay uplink and / or downlink data transmission between the access node and the terminal. In particular, the second access node may be referred to as an enhancement node for the data transmission of the terminal, for example, as a relay node for the data transmission of the terminal. Therefore, information transmitted between the first access node and the terminal may be transmitted in a duplicate manner between the first access node and the terminal via the second access node.

[0216] In particular, the term "data transmission" may include the transmission of signalling data and / or payload data in an uplink direction from the terminal to the mobile network and / or in a downlink direction from the mobile network to the terminal.

[0217] In particular, the first connection and the second connection may be independent of each other and may include respective radio bearers established in connection with data transmission.

[0218] In particular, the first access node is referred to as the "source eNB" in the described embodiments and the first connection is Figure 4 In particular, the second access node may be referred to as an "assisting eNB" in the described embodiments. Figure 4 is marked as "enhanced". Note that Figure 1 and Figure 2 The target eNB described here also refers to an access node suitable for controlling data transmission of the terminal.

[0219] In particular, in the data transmission of the terminal, data is sent from a first access node to the terminal and a copy of the data is sent from a second access node to the terminal. The first access node may have the corresponding data copied and may have sent a copy of the data to the second access node.

[0220] 2. The method of embodiment 1, wherein the determining step causes the first connection to have failed, and wherein the adapting step comprises:

[0221] --Maintain connections without failure.

[0222] 3. The method of any preceding embodiment, wherein the determining step results in the first connection having failed, wherein the adapting step comprises:

[0223] --Switching, by the first access node, the terminal from the first access node to the second access node, and disconnecting the first connection.

[0224] For example, the first access node may initiate a handover of the terminal by sending a handover request to the second access node. The second access node may forward or relay the handover request to the terminal. The first access node may stop controlling data transmission of the terminal. In LTE, the latter may be related to stopping RRC diversity. The RRC diversity used in the first access node may be related to sending data directly to the terminal and to sending a copy of the data, which is sent by the first access node to the terminal, to a second access node for relaying a copy of the data to the terminal by the second access node.

[0225] Thus, stopping RRC diversity may mean no longer duplicating the transmitted data, thus maintaining a direct connection only to the terminal to keep regular functionality. Or in other words, in particular with regard to LTE, the latter may relate to stopping RRC signaling duplication and forwarding to the second access node.

[0226] 4. The method according to embodiment 3, wherein the adapting step further comprises:

[0227] -- Transferring, by the first access node, a control capability for controlling data transmission of the terminal from the first access node to the second access node.

[0228] In particular, refer to Fig. 9 Embodiments 3 and 4 will be described.

[0229] 5. The method of any preceding embodiment, wherein the determining step results in the second connection having failed, wherein the adapting step comprises:

[0230] -- request by the first access node to disconnect the second connection, and

[0231] -- Stop using the second access node for data transmission of the terminal.

[0232] In particular, the step of stopping using the second access node for data transmission may comprise: stopping duplicating data sent from the first access node to the terminal and stopping sending the duplicated data to the second access node. In particular, this step may be embodied as stopping RRC diversity, involving no longer duplicating data or messages that may be sent to the second access node. Thus, only a direct connection from the first access node to the UE may be maintained, the latter being referred to as a regular function of the first access node of the mobile network.

[0233] In particular, refer to Figure 8 Embodiment 5 will be described.

[0234] 6. The method of any preceding embodiment, wherein the determining step results in one of the first connection and the second connection having failed, wherein the obtaining step comprises:

[0235] --The terminal sends quality degradation information to the access node whose connection to the terminal has not failed among the first access node and the second access node.

[0236] In particular, as referenced Figure 8 As explained, if the second connection may have failed, quality degradation information may be sent to the first access node. If the first connection may have failed, quality degradation information may be sent to the second access node and may be relayed or forwarded by the second access node to the first access node.

[0237] 7. The method according to embodiment 6, wherein the quality degradation information includes a failure notification indication, in particular an RLF warning indication as described above.

[0238] In particular, the failure notification indication may represent an individual indication, in particular included in a conventional message or a new type of message, or may be a message of a specific type.

[0239] In particular, according to any of the aforementioned embodiments, the quality degradation information may include at least one information selected from the following group:

[0240] a cell identity indication indicating an area served by the access node associated with the failed connection, in particular, an identity of a cell, in particular, a PCell identity (ID), a cell global ID, a physical cell ID, or a carrier frequency of the cell,

[0241] - information about measurements obtained for the area served by the access node associated with the failed connection and for a previous time period,

[0242] - information about measurements obtained for the area, in particular the cell, served by the access node associated with the non-failed connection and obtained for a previous time period;

[0243] - information about measurement results obtained for at least one further area, in particular a further cell, served by a further access node different from the first access node and the second access node and obtained for a previous time period, in particular an identifier of the measurement,

[0244] --Connection indication indicating failed connection,

[0245] --failure timer for failed connections, and

[0246] --Reason for failure.

[0247] In particular, the failure reason may include at least one of the following:

[0248] - expiration of a timer, starting the timer after a condition is satisfied for a predetermined number of counters and stopping the timer after another condition is satisfied for a predetermined number of counters; for example, in LTE the latter may correspond to "out of sync" referring to expiration of the RLF timer,

[0249] - the maximum number of scheduling requests has been sent on the corresponding connection; for example, in LTE the latter may correspond to the maximum number of RLC retransmissions having been reached,

[0250] - a maximum number of data retransmissions has been sent by the terminal on the corresponding connection; for example, in LTE the latter may correspond to a maximum number of scheduling requests having been reached; and

[0251] - A maximum number of unsuccessful random access attempts has been sent by the terminal on the corresponding connection without receiving a data transmission on the corresponding connection; for example, in LTE the latter may correspond to a Random Access Channel (RACH) failure.

[0252] In particular, the at least one information mentioned above may be sent together with the failure notification indication in one message, or may be sent after the failure notification indication sent in the obtaining step.

[0253] 8. The method of any preceding embodiment, wherein the determining step results in the first connection and the second connection having failed, wherein the adapting step comprises:

[0254] - Establishing a further connection between the terminal and a further access node of the mobile network.

[0255] In particular, according to the aforementioned embodiment, the acquiring step may be performed by the terminal. The establishing step may be initiated by the terminal. The further access node may be different from the first access node and the second access node, or may be one of the first access node and the second access node.

[0256] 9. The method according to any preceding embodiment, wherein the method further comprises:

[0257] - determining at least one key performance indicator of the mobile network,

[0258] The adapting step comprises adapting at least one system setting of the mobile network based on the at least one key performance indicator.

[0259] In particular, alternatively or additionally, the adaptation step of the system settings may be based on quality degradation information obtained, in particular sent in an RLF report.The purpose of such adaptation may be an improvement of one of the key performance indicators in the network.

[0260] In particular, the system settings may be related to characteristics of the first access node and / or access node or may be related to characteristics of a further access node of the mobile network.

[0261] In particular, embodiments 2 to 8 may describe an immediate or ad hoc adaptation of a mobile network.Embodiment 9 may describe an overall adaptation of a mobile network over an intermediate or long term timeframe.

[0262] 10. The method of any preceding embodiment, wherein the determining step is performed by the terminal and comprises evaluating the quality of the first connection and evaluating the quality of the second connection.

[0263] In particular, the step of evaluating the quality of the first connection and the step of evaluating the quality of the second connection may be performed independently of each other.

[0264] 11. The method according to any preceding embodiment, wherein the respective evaluating step comprises evaluating synchronization of the terminal with the respective access node with respect to data transmission on the respective connection.

[0265] In particular, if the terminal may not be properly synchronized for data transmission on the respective connection, a quality degradation of the respective connection may be determined. In particular, the determined connection quality degradation may correspond to a connection failure.

[0266] 12. A method according to any of the preceding embodiments, wherein the determining step comprises: in particular, for each of the first connection and the second connection, using a timer in the terminal and a counter in the terminal, the counter being associated with the fulfillment of a condition, wherein if the timer expires, it is determined that the quality of the corresponding connection has degraded, the timer is started after the condition is fulfilled for a predetermined number of the counter, and the timer is stopped after another condition is fulfilled for a predetermined number of the counter.

[0267] In particular, the timer may correspond to the T310 timer and the counter may correspond to the constant N310, both aspects being described above.In particular, the same type or different types of timers and / or counters may be used for the first connection and the second connection.

[0268] In particular, according to any of the preceding embodiments, the determining step comprises: in particular, for each of the first connection and the second connection, using a timer in the terminal and a plurality of counters in the terminal, one counter being associated with the fulfillment of a condition, wherein if the timer expires, it is determined that the quality of the corresponding connection has degraded, the timer is started after the condition has been fulfilled for a predetermined number of the counters, and the timer is stopped after another condition has been fulfilled for a predetermined number of another counters.

[0269] In particular, as described above, the timer may correspond to the T310 timer and the plurality of counters may correspond to the counters or constants N310, N311. In particular, the same type or different types of timers and / or counters may be used for the first connection and the second connection.

[0270] 13. The method according to embodiments 10 to 12, wherein the corresponding evaluation step comprises: evaluating whether a maximum number of scheduling requests have been sent on the corresponding connection.

[0271] 14. The method according to embodiments 10 to 13, wherein the corresponding evaluation step includes: evaluating whether a maximum number of data retransmissions has been sent by the terminal on the corresponding connection.

[0272] 15. The method according to embodiments 10 to 14, wherein the corresponding evaluation step includes: evaluating whether a maximum number of unsuccessful random access requests has been sent by the terminal on the corresponding connection without receiving a data transmission on the corresponding connection.

[0273] 16. The method of any preceding embodiment, wherein the obtaining step comprises: sending quality degradation information by the second access node to the first access node.

[0274] In particular, the latter embodiments may be applied to the following situations: at least one of the first connection and the second connection may include degraded or low quality but may not have failed. For example, the quality degradation information may include a channel quality indication. The determining step may be performed by the second access node, which may monitor a parameter associated with the channel quality information and / or may determine a value of the parameter.

[0275] In particular, the latter embodiments may be applied to embodiments related to handover of the terminal and to embodiments related to handover in combination with transfer of control capability.

[0276] 17. An embodiment of a method for adapting a mobile network, wherein a terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection, wherein the first access node controls data transmission of the terminal, and wherein the second access node assists data transmission of the terminal, the method being performed by the terminal and comprising:

[0277] - determining whether the quality of at least one of the first connection and the second connection is degraded, and

[0278] - obtaining quality degradation information about quality degradation of at least one of the first connection and the second connection based on the determining step for use in adapting the mobile network based on the obtaining step.

[0279] 18. An embodiment of a method for adapting a mobile network, wherein a terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection, wherein the first access node controls data transmission of the terminal, and wherein the second access node assists data transmission of the terminal, the method being performed by the first access node and comprising:

[0280] - obtaining quality degradation information about quality degradation of at least one of the first connection and the second connection based on the determination of whether the quality of at least one of the first connection and the second connection is degraded, and

[0281] -Adapting the mobile network based on the acquisition step.

[0282] 19. An embodiment of a method for adapting a mobile network, wherein a terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection, wherein the first access node controls data transmission of the terminal, and wherein the second access node assists data transmission of the terminal, the method being performed by the second access node and comprising:

[0283] - adapting the mobile network based on the acquired quality degradation information about the quality degradation of at least one of the first connection and the second connection, the acquiring being based on a determination whether the quality of at least one of the first connection and the second connection is degraded.

[0284] 20. An embodiment of a terminal for adapting a mobile network, wherein the terminal is connected to a first access node of the mobile network via a first connection and to a second access node via a second connection, wherein the first access node controls data transmission of the terminal, and wherein the second access node assists data transmission of the terminal, the terminal comprising:

[0285] - a determination unit adapted to determine whether the quality of at least one of the first connection and the second connection is degraded, and - an acquisition unit adapted to acquire quality degradation information about the quality degradation of at least one of the first connection and the second connection based on the determination for adapting the mobile network based on the acquired quality degradation information.

[0286] In particular, the terminal may be adapted to perform a method according to any one of embodiments 1 to 18.

[0287] 21. An access node for adapting a mobile network, wherein a terminal is connected to the access node of the mobile network via a connection and to another access node via another second connection, wherein the access node controls data transmission of the terminal and the other access node assists data transmission of the terminal, the access node comprising:

[0288] - an acquisition unit adapted to acquire quality degradation information about quality degradation of at least one of the first connection and the second connection based on a determination whether the quality of at least one of the first connection and the second connection is degraded, and - an adaptation unit adapted to adapt the mobile network based on the acquired quality degradation information.

[0289] In particular, the access node may be adapted to perform a method according to any one of embodiments 1 to 17 and 19.

[0290] 22. An access node for adapting a mobile network, wherein a terminal is connected to the access node of the mobile network via a connection and to another access node via another connection, wherein the other access node controls data transmission of the terminal and the access node assists data transmission of the terminal, the access node comprising:

[0291] - an adaptation unit adapted to adapt the mobile network based on acquired quality degradation information about quality degradation of at least one of the connection and the further connection, the acquisition of the quality degradation information being based on a determination whether the quality of at least one of the connection and the further connection is degraded.

[0292] In particular, the access node may be adapted to perform a method according to any one of embodiments 1 to 17 and 19.

[0293] 23. A mobile network embodiment, comprising a terminal according to embodiment 20, a first access node according to embodiment 21, and a second access node according to embodiment 22.

[0294] 24. A computer program, when executed by a processor, adapted to implement or control a method for processing a terminating circuit switched signaling service to a terminal in a mobile network according to any one of embodiments 1 to 19.

[0295] Note that the above-described embodiments related to the methods according to embodiments 1 to 16 apply to the embodiments related to other methods according to embodiments 17 to 19, the terminal, the first access node, the second access node, the mobile network and the computer program.

Claims

1. A method for communicating in a mobile network in a first access node, the first access node being connected to a user equipment via a first connection, the first access node controlling data transmission of the user equipment, wherein the data transmission is facilitated by a second access node, the second access node being connected to the user equipment via a second connection, the method comprising: receiving a failure notification indication from the user equipment, the failure notification indication indicating a failure of the second connection and a failure cause related to expiration of a timer, the expiration of the timer indicating a determination that the quality of the second connection is degraded, wherein the timer is started after a condition related to degradation of the quality of the second connection is satisfied for a predetermined number of counters and the timer is stopped after another condition related to non-degradation of the quality of the second connection is satisfied for a predetermined number of counters, and The mobile network is adapted based on the received failure notification indication.

2. The method according to the preceding claim, wherein said adapting said mobile network comprises: At least one connection between the user equipment and the mobile network is adapted based on the failure notification indication.

3. The method according to claim 1 or 2, wherein the second connection has failed, and wherein the adapting comprises: requesting that the second connection be disconnected, and Stop using the second access node for the data transmission of the user equipment.

4. A method in a user equipment for communicating in a mobile network, wherein the user equipment is connected to a first access node of the mobile network via a first connection and to a second access node of the mobile network via a second connection, the first access node controlling data transmission of the user equipment and the second access node assisting the data transmission of the user equipment, the method comprising: determining that the second connection has failed, wherein the determining comprises: using, for the second connection, a timer in the user equipment and a counter in the user equipment, the counter being associated with the fulfillment of a condition, wherein the failure of the second connection is determined by expiration of the timer, the expiration of the timer indicating a determination of degradation of the quality of the second connection, starting the timer after a condition related to degradation of the quality of the second connection is fulfilled for a predetermined number of the counter, and stopping the timer after another condition related to non-degradation of the quality of the second connection is fulfilled for a predetermined number of the counter, and A failure notification indication is sent to the first access node along with a failure cause related to the expiration of the timer. The method of claim 4 , wherein the failure notification indication is a radio link failure (RLF) warning indication.

6. The method of claim 4 or 5, wherein a cell identity indication is sent to the first access node, the cell identity indication indicating an identity of a cell served by the second access node associated with the failed connection. 7 . The method according to claim 6 , wherein the cell identity indication comprises a cell global ID, a physical cell ID, or a carrier frequency of the cell.

8. The method according to claim 4 or 5, wherein information about measurements obtained for an area served by the second access node associated with the failed connection is sent to the first access node.

9. The method of claim 4 or 5, wherein information about measurements obtained for cells served by the first access node associated with a non-failed connection is sent to the first access node.

10. The method of claim 4 or 5, wherein a connection indication indicating a failed connection is sent to the first access node.

11. The method of claim 4 or 5, wherein said determining that said second connection has failed comprises evaluating a quality of said second connection.

12. The method of claim 11, wherein the evaluating comprises evaluating synchronization of the user equipment with the second access node for the data transmission on the second connection.

13. The method of claim 11, wherein the evaluating comprises evaluating whether a maximum number of data retransmissions have been sent by the user equipment on the second connection.

14. The method according to claim 11, wherein the evaluating comprises evaluating whether a maximum number of unsuccessful random access attempts have been sent by the user equipment on the second connection without receiving a data transmission on the second connection.

15. The method according to claim 4 or 5, further comprising: A request is received from the first access node to disconnect the second connection.

16. The method according to claim 15, further comprising: Stop using the second access node for the data transmission of the user equipment.

17. A method in a first access node and in a second access node for communicating in a mobile network, wherein the first access node is connected to a user equipment via a first connection, wherein the first access node controls data transmission of the user equipment, wherein the second access node is connected to the user equipment via a second connection, the second access node assists the data transmission of the user equipment, wherein the second connection has failed, and wherein the first access node adapts the mobile network based on a failure notification indication, the adaptation comprising requesting the second access node to disconnect the second connection, the method comprising: receiving a request from the first access node to disconnect the second connection, The second access node is caused to stop the data transmission for the user equipment.

18. A method for communicating in a mobile network, wherein a user equipment is connected to a first access node of the mobile network via a first connection and to a second access node of the mobile network via a second connection, wherein the first access node controls data transmission of the user equipment and wherein the second access node assists the data transmission of the user equipment, the method comprising: receiving, by the first access node, a failure notification indication indicating a failure of the second connection and a cause of the failure related to an expiration of a timer, the expiration of the timer indicating a determination of a degradation of the quality of the second connection, wherein the timer is started after a condition related to degradation of the quality of the second connection is satisfied for a predetermined number of the counter and the timer is stopped after another condition related to non-degradation of the quality of the second connection is satisfied for a predetermined number of the counter, The first access node sends a request to disconnect the second connection to the second access node, receiving, by the second access node from the first access node, the request to disconnect the second connection, The first access node stops using the second access node for the data transmission of the user equipment.

19. A user equipment for communicating in a mobile network, wherein the user equipment is adapted to be connected to a first access node of the mobile network via a first connection and to a second access node of the mobile network via a second connection, the first access node controlling data transmission of the user equipment and the second access node facilitating the data transmission of the user equipment, the user equipment comprising a processor and a memory storing a computer program, the computer program, when executed by the processor, causing the user equipment to: Determining that the second connection has failed, wherein the determining comprises: for the second connection, using a timer in the user equipment and a counter in the user equipment, the counter being associated with the fulfillment of a condition, wherein the failure of the second connection is determined by expiration of the timer, the expiration of the timer indicating a determination of degradation of the quality of the second connection, starting the timer after a condition related to degradation of the quality of the second connection is fulfilled for a predetermined number of the counter, and stopping the timer after another condition related to non-degradation of the quality of the second connection is fulfilled for a predetermined number of the counter, and A failure notification indication is sent to the first access node along with a failure cause related to the expiration of the timer.

20. The user equipment according to claim 19, wherein the user equipment is adapted to perform the method according to any one of claims 5 to 16.

21. A first access node for communicating in a mobile network, wherein the first access node is adapted to be connected to a user equipment via a connection, wherein the first access node is adapted to control data transmission of the user equipment, wherein the data transmission of the user equipment is facilitated by a second access node of the mobile network, the second access node being connected to the user equipment via another connection, wherein the first access node comprises a processor and a memory storing a computer program, which, when executed by the processor, causes the first access node to: receiving a failure notification indication from the user equipment, the failure notification indication indicating a failure of the other connection and a cause of the failure related to expiration of a timer, the expiration of the timer indicating a determination of degradation of the quality of the other connection, wherein the timer is started after a condition related to degradation of the quality of the other connection is satisfied for a predetermined number of the counter and the timer is stopped after another condition related to non-degradation of the quality of the other connection is satisfied for a predetermined number of the counter, and The mobile network is adapted based on the received failure notification indication.

22. The first access node according to claim 21, wherein the first access node is adapted to perform the method according to claim 2 or 3.

23. A mobile network, the mobile network comprising a first access node and a second access node, wherein the first access node is adapted to be connected to a user equipment via a first connection, wherein the first access node is adapted to control data transmission of the user equipment, wherein the second access node is adapted to be connected to the user equipment via a second connection, wherein the second access node is adapted to assist the data transmission of the user equipment, wherein the second connection has failed, wherein the first access node is adapted to adapt the mobile network based on a failure notification indication, the adaptation comprising requesting the second access node to disconnect the second connection, and wherein the second access node comprises a processor and a memory storing a computer program, which, when executed by the processor, causes the second access node to: receiving a request from the first access node to disconnect the connection, The second access node is caused to stop the data transmission for the user equipment.

24. A mobile network according to claim 23, comprising a user equipment according to claim 19 or 20.

25. A computer readable medium having stored thereon a computer program, which, when executed by a processor, is adapted to perform or control the method for adapting a mobile network according to any one of claims 1 to 18.

26. A computer program product comprising program code to be executed by at least one processor, thereby causing the at least one processor to perform the method according to any one of claims 1 to 18.

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