WO2018077416A1

WO2018077416A1 - Pro-active transmission of system information to reduce interruption time after radio link failure for wireless networks

Info

Publication number: WO2018077416A1
Application number: PCT/EP2016/076047
Authority: WO
Inventors: Ahmad AWADA; Ingo Viering
Original assignee: Nokia Technologies Oy
Priority date: 2016-10-28
Filing date: 2016-10-28
Publication date: 2018-05-03

Abstract

A technique includes sending, by a user device to a source cell, a measurement report indicating a handover to a target cell, receiving, by the user device from the source cell, a message including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell, and performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

Description

DESCRIPTION TITLE

Pro-Active Transmission of System I nformation To Reduce Interruption Time After Radio Link

Failure For Wireless Networks

TECHNICAL FIELD

[0001] This description relates to communications, and in particular, to a pro-active transmission of system information to reduce interruption time after a radio link failure for wireless networks.

BACKGROUND

[0002] A communication system may be a facility that enables communication between two or more nodes or devices, such as fixed or mobile communication devices. Signals can be carried on wired or wireless carriers.

[0003] An example of a cellular communication system is an architecture that is being standardized by the 3^rd Generation Partnership Project (3GPP). A recent development in this field is often referred to as the Long Term Evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. E-UTRA (evolved UMTS Terrestrial Radio Access) is the air interface of 3GPP's Long Term Evolution (LTE) upgrade path for mobile networks. In LTE, base stations or access points (APs), which are referred to as enhanced Node Bs (eNBs), provide wireless access within a coverage area or cell. In LTE, mobile devices, user devices or mobile stations are referred to as user equipments (UEs).

[0004] Various techniques may be used to detect a radio link failure (RLF). For example, in some wireless networks, a radio link failure (RLF) may occur based on one or more out-of-sync indications. For example, a user device may send an out-of-sync indication to an upper layer (e.g., to the radio resource control (RRC) layer of the user device) if a measured signal quality (e.g., reference signal received power, reference signal received quality, SI NR or signal-to-interference plus noise ratio or other signal quality) is less than Qout. For example, when a threshold number of out-of-sync indications are received by the upper (e.g., RRC) layer, then a timer is started. And, for example, a radio link failure (RLF) may be declared by the user device when the timer expires.

SUMMARY

[0005] According to an example implementation, a method is provided including receiving, by a user device from a source cell in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell;

measuring, by the user device, a received signal from each of a plurality of cells; determining that the first measurement event has occurred; sending, by the user device to the source cell, a system information triggering measurement report based on the occurrence of the first measurement event; receiving, by the user device from the source cell in response to sending the system information triggering measurement report, system information for at least the reconnection candidate cell; and performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0006] According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: receive, by a user device from a source cell in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; measure, by the user device, a received signal from each of a plurality of cells; determining that the first measurement event has occurred; send, by the user device to the source cell, a system information triggering measurement report based on the occurrence of the first measurement event; receive, by the user device from the source cell in response to sending the system information triggering measurement report, system information for at least the reconnection candidate cell; and perform, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0007] According to an example implementation, an apparatus includes means for receiving, by a user device from a source cell in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; means for measuring, by the user device, a received signal from each of a plurality of cells; means for determining that the first measurement event has occurred; means for sending, by the user device to the source cell, a system information triggering measurement report based on the occurrence of the first measurement event; means for receiving, by the user device from the source cell in response to sending the system information triggering measurement report, system information for at least the reconnection candidate cell; and means for performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell. [0008] According to an example implementation, a computer program product includes a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method including: receiving, by a user device from a source cell in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; measuring, by the user device, a received signal from each of a plurality of cells; determining that the first measurement event has occurred; sending, by the user device to the source cell, a system information triggering measurement report based on the occurrence of the first measurement event; receiving, by the user device from the source cell in response to sending the system information triggering measurement report, system information for at least the reconnection candidate cell; and performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0009] According to an example implementation, a method is provided including sending, by a source cell to a user device in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell;

receiving, by the source cell from the user device, a system information triggering measurement report based on an occurrence of the first measurement event; obtaining, by the source cell from the reconnection candidate cell, system information for the reconnection candidate cell; sending, by the source cell to the user device in response to receiving the system information triggering measurement report, the system information for the reconnection candidate cell.

[0010] According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: send, by a source cell to a user device in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; receive, by the source cell from the user device, a system information triggering measurement report based on an occurrence of the first measurement event; obtain, by the source cell from the reconnection candidate cell, system information for the reconnection candidate cell; and send, by the source cell to the user device in response to receiving the system information triggering measurement report, the system information for the reconnection candidate cell.

[0011 ] According to an example implementation, an apparatus includes means for sending, by a source cell to a user device in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; means for receiving, by the source cell from the user device, a system information triggering measurement report based on an occurrence of the first measurement event; means for obtaining, by the source cell from the reconnection candidate cell, system information for the reconnection candidate cell; and means for sending, by the source cell to the user device in response to receiving the system information triggering measurement report, the system information for the reconnection candidate cell.

[0012] According to an example implementation, a computer program product includes a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method including: sending, by a source cell to a user device in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; receiving, by the source cell from the user device, a system information triggering measurement report based on an occurrence of the first measurement event; obtaining, by the source cell from the reconnection candidate cell, system information for the reconnection candidate cell; sending, by the source cell to the user device in response to receiving the system information triggering measurement report, the system information for the reconnection candidate cell.

[0013] According to an example implementation, a method is provided including sending, by a user device to a source cell, a measurement report indicating a handover to a target cell; receiving, by the user device from the source cell, a message including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell; and performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0014] According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: send, by a user device to a source cell, a measurement report indicating a handover to a target cell; receive, by the user device from the source cell, a massage including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell; and perform, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0015] According to an example implementation, an apparatus includes means for sending, by a user device to a source cell, a measurement report indicating a handover to a target cell; means for receiving, by the user device from the source cell, a message including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell; and means for performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0016] According to an example implementation, a computer program product includes a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method including: sending, by a user device to a source cell, a measurement report indicating a handover to a target cell; receiving, by the user device from the source cell, a message including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell; and performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0017] According to an example implementation, a method is provided including receiving, by a source cell from a user device, a measurement report indicating a handover to a target cell; making a handover decision to perform a handover of the user device to the target cell; sending, by the source cell to the user device, a message including a handover command for the user device to perform a handover to the target cell, and system information for a reconnection candidate cell; wherein the system information allows the user device to perform a connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[0018] According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: receive, by a source cell from a user device, a measurement report indicating a handover to a target cell; make a handover decision to perform a handover of the user device to the target cell; send, by the source cell to the user device, a message including a handover command for the user device to perform a handover to the target cell, and system information for a reconnection candidate cell; wherein the system information allows the user device to perform a connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell. [0019] According to an example implementation, an apparatus includes means for receiving, by a source cell from a user device, a measurement report indicating a handover to a target cell; means for making a handover decision to perform a handover of the user device to the target cell; and means for sending, by the source cell to the user device, a message including a handover command for the user device to perform a handover to the target cell, and system information for a reconnection candidate cell; wherein the system information allows the user device to perform a connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[0020] According to an example implementation, a computer program product includes a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method including: receiving, by a source cell from a user device, a measurement report indicating a handover to a target cell; making a handover decision to perform a handover of the user device to the target cell; sending, by the source cell to the user device, a message including a handover command for the user device to perform a handover to the target cell, and system information for a reconnection candidate cell; wherein the system information allows the user device to perform a connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[0021] The details of one or more examples of implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.

BRIEF DESCRI PTION OF TH E DRAWINGS

[0022] FIG. 1 is a block diagram of a wireless network according to an example implementation.

[0023] FIG. 2 is a diagram illustrating operations of a radio resource control re- establishment procedure according to an example implementation.

[0024] FIG. 3 is a diagram illustrating operation of a wireless network in which a user device receives system information for a reconnection candidate cell based on a system information (SI) triggering measurement report according to an example implementation.

[0025] FIG. 4 is a diagram illustrating operation of a wireless network in which a user device receives system information for a reconnection candidate cell within a handover command to perform a handover to a target cell according to an example implementation.

[0026] FIG. 5 is a flow chart illustrating operation of a user device according to an example implementation.

[0027] FIG. 6 is a flow chart illustrating operation of a cell or base station according to an example implementation.

[0028] FIG. 7 is a flow chart illustrating operation of a user device according to an example implementation.

[0029] FIG. 8 is a flow chart illustrating operation of a cell or base station according to an example implementation.

[0030] FIG. 9 is a block diagram of a node or wireless station (e.g. , network device, base station/access point or mobile station/user device/UE) according to an example implementation.

DETAILED DESCRI PTION

[0031 ] FIG. 1 is a block diagram of a wireless network 130 according to an example implementation. In the wireless network 130 of FIG. 1 , user devices 131 , 132, 133 and 135, which may also be referred to as mobile stations ( Ss) or user equipment (UEs), may be connected (and in communication) with a base station (BS) 134, which may also be referred to as an access point (AP), an enhanced Node B (eNB) or a network node. At least part of the functionalities of an access point (AP), base station (BS) or (e)Node B (eNB) may be also be carried out by any node, server or host which may be operably coupled to a transceiver, such as a remote radio head. BS (or AP) 134 provides wireless coverage within a cell 136, including to user devices 131 , 132, 133 and 135. Although only four user devices are shown as being connected or attached to BS 134, any number of user devices may be provided. BS 134 is also connected to a core network 150 via a S1 interface 151. This is merely one simple example of a wireless network, and others may be used.

[0032] A user device (user terminal, user equipment (UE) or mobile station) may refer to a portable computing device that includes wireless mobile communication devices operating with or without a subscriber identification module (SIM), including, but not limited to, the following types of devices: a mobile station (MS), a mobile phone, a cell phone, a smartphone, a personal digital assistant (PDA), a handset, a device using a wireless modem (alarm or measurement device, etc.), a laptop and/or touch screen computer, a tablet, a phablet, a game console, a notebook, and a multimedia device, as examples. It should be appreciated that a user device may also be a nearly exclusive uplink only device, of which an example is a camera or video camera loading images or video clips to a network.

[0033] By way of illustrative example, the various example implementations or techniques described herein may be applied to various user devices, such as machine type communication (MTC) user devices, enhanced machine type communication (eMTC) user devices, Internet of Things (loT) user devices, and/or narrowband loT user devices. loT may refer to an ever-growing group of objects that may have Internet or network connectivity, so that these objects may send information to and receive information from other network devices. For example, many sensor type applications or devices may monitor a physical condition or a status, and may send a report to a server or other network device, e.g., when an event occurs. Machine Type Communications (MTC, or Machine to Machine communications) may, for example, be characterized by fully automatic data generation, exchange, processing and actuation among intelligent machines, with or without intervention of humans.

[0034] Also, in an example implementation, a user device or U E may be a UE/user device with ultra reliable low latency communications (U RLLC) applications. A cell (or cells) may include a number of user devices connected to the cell, including user devices of different types or different categories, e.g., including the categories of MTC, NB-loT, URLLC, or other UE category.

[0035] In LTE (as an example), core network 150 may be referred to as Evolved Packet Core (EPC), which may include a mobility management entity (MME) which may handle or assist with mobility/handover of user devices between BSs, one or more gateways that may forward data and control signals between the BSs and packet data networks or the Internet, and other control functions or blocks.

[0036] The various example implementations may be applied to a wide variety of wireless technologies or wireless networks, such as LTE, LTE-A, 5G, cmWave, and/or mmWave band networks, loT, MTC, eMTC, U RLLC, etc., or any other wireless network or wireless technology. These example networks or technologies are provided only as illustrative examples, and the various example implementations may be applied to any wireless technology/wireless network.

[0037] The 5th Generation (5G) of wireless networks provides expansion of International Mobile Telecommunications (IMT) that go beyond those of IMT-2000 and IMT-Advanced mobile broadband (MBB) service, and also envisioning to address new services and use cases. These new services are not only for human interaction, but also a huge growth in machine-type communications (MTC) driven by e.g., factory automation and flexible process control. Another new use case is ultra reliable low latency communications (URLLC), which may require very high reliability and low latency.

[0038] According to an example implementation, when a radio link failure (RLF) occurs for a user device or UE, the user device may attempt to re-establish a connection to a new cell (which may be different from the source cell if a handover command is not received or may be different from a target cell if a handover command was received) by sending a connection re-establishment request. The user device may typically first receive system information (SI) of the new cell before sending the connection re-establishment request to the new cell. The system information may include one or more access parameters for use in accessing or establishing a connection to the new cell. The connection re-establishment procedure is typically delayed until the user device receives the system information for the new cell that it is attempting to connect to.

[0039] FIG. 2 is a diagram illustrating operations of a radio resource control re- establishment procedure according to an example implementation. During T target 212, the user device may select a target cell and acquire or obtain its system information (SI). During T RACH 214 (a time period for random access procedure) the user device may perform random access with the target cell. And, during T signaling 21 6, the user device may send a connection re- establishment request to the target cell and receive a response from the target cell.

[0040] During the connection re-establishment procedure, the user device (or UE) cannot receive data until it is successfully completed. As shown in FIG. 2, the interruption time may, for example, include the time T target for selecting a new target cell and acquiring its System

Information (SI), the time T RACH for performing RACH access (random access procedure) and the time T signalling for sending the re-establishment request message and receiving a response from the network. The user device has to acquire the SI of the target cell to check if it is suitable for cell selection and to obtain the necessary radio resource configurations for performing RACH access and transmitting/receiving the RRC Connection Re-establishment Request/Response to/from the network.

[0041] One important factor contributing to the total interruption time is T target 212, which depends on the periodicity of the Master Information Block (MIB) and System Information Blocks (SIBs) containing the relevant cell access information. For example, in LTE, the cell access information is provided by SIB 1 and SIB 2. The periodicity of MIB and SIB 1 is fixed to 40 ms and 80 ms, respectively, whereas the periodicity of SIB 2 is indicated by SIB 1 and can be configured to 80 ms, 1 60 ms, 320 ms, 640 ms and 1280 ms, 2560 ms and 5120 ms. In another illustrative example implementation, for 5G networks, for example, the MIB may be broadcasted every 40 ms and the content of SIB 1 and SIB 2 may be part of a xSystem Information Block (xSIB) that may be broadcasted every, e.g., 80 ms, or other time period. These are merely some examples, and other time periods and technologies may be used. Thus, the user device may typically wait until the system information (SI) is transmitted again by the target cell before the user device can establish a connection with the target cell. Thus, waiting to receive the system information from the target cell may increase the interruption time for the user device after the RLF.

[0042] Therefore, various example implementations are described for decreasing the interruption time after a RLF.

[0043] RLFs may occur for a variety of different reasons, and/or at different times or points during a communication process For example, some radio link failures (RLFs) may occur for a user device due to: 1 ) a too early handover (H/O) to a target cell, resulting in RLF shortly after being handed over from source cell A to target cell B, causing the user device to reconnect to the source cell after the RLF (e.g., A-B-A); 2) a too late H/O to a target cell, where the RLF occurred for the user device with respect to the source cell A before the user device is handed over to a target cell B (e.g., A-B), and the RLF may even have occurred before the user device measured the signal condition (e.g., A3 condition) or reported the cell change (or H/O) triggering measurement report to the source cell; and 3) a H/O to a wrong cell, which may cause the user device to reconnect to cell C shortly after being handed over to target cell B from source cell A (e.g., A-B-C).

[0044] According to an example implementation, a cell or BS may receive measurement reports from user devices. An example trigger for a measurement report to be sent to the current (or source cell) from a user device may include, for example, an occurrence of the A3 trigger, which may include, in a simplified form:

[0045] Mn> Ms+Off. (Eqn. 1 ). This Eqn. 1 may describe a very simple A3 trigger condition that may be triggered or expire if a signal measurement of the neighbor node (Mn) is greater than the signal measurement of the source node (Ms) plus an offset (Off). The signal measurement may be signal strength (such as reference signal received power or RSRP, or a received signal strength indication or RSSI), a signal quality (such as reference signal received quality), or other signal measurement.

[0046] According to an example implementation, a Mobility Robustness Optimization (MRO) entity may be used to detect and improve errors in the mobility configuration (e.g., to reduce RLFs). For example, according to an example implementation, the MRO entity, which may be a centralized MRO entity within the core network or a BS, or may be a distributed MRO entity among multiple sites or multiple BSs, may collect data on various RLFs, and then may optimize or at least adjust one or more parameters, such as one or more offsets for H/O trigger conditions, to decrease the RLFs. In addition, according to an example implementation, the MRO may also be used to identify, for each source cell, target cell or cell border (e.g., source cell/target cell combination), one or more reconnection candidate cells. A reconnection candidate cell may be a cell that a user device may (e.g., may typically) reconnect to after a radio link failure (RLF), e.g., for a specific source cell and/or a specific target cell, or other condition (e.g., based on a mobility status of the user device, such as slow moving user device, or fast moving user device). For example, for a given source cell, there may be one or more reconnection candidate cells that most (or a significant percentage) of the user devices may typically reconnect to after a RLF, e.g., before receiving a handover (H/O) command, or during another point or time.

[0047] According to an example implementation, the interruption time after a RLF may be decreased by providing the user device with system information (SI) of one or more reconnection candidate cells before a RLF occurs for the user device, so that the user device may more quickly reconnect to the cell that the user device may typically connect to after a RLF, because the user device need not wait to receive the SI from the new cell (reconnection candidate cell) after the RLF. According to an example implementation, the system information (SI) for a reconnection candidate cell may be provided or communicated to the user device via two different approaches, such as: First, system information (SI) for the reconnection candidate cell may be provided or sent to the user device based on a SI triggering measurement report that is triggered and sent to the source cell before the user device sends a cell change (or H/O) triggering measurement report, e.g., based on different offsets for these two different measurement reports (see, e.g., FIG. 3). Second, system information (SI) for a reconnection candidate cell may be sent to the user device as part of a handover (H/O) command sent from the source cell to the user device (see, e.g., FIG. 4). Then, if a RLF occurs for the user device, the user device may use this received SI to more quickly reestablish a connection to the reconnection candidate cell, e.g., without the user device waiting to receive the SI periodically transmitted from the reconnection candidate cell.

[0048] FIG. 3 is a diagram illustrating operation of a wireless network in which a user device receives system information for a reconnection candidate cell based on a system information (SI) triggering measurement report according to an example implementation. In FIG. 3, a user device 132, a source cell A and a reconnection candidate cell C are shown. A target cell B (as a target cell for handover for user device 132) is not shown in FIG. 3. At 310, the source cell A may determine or may obtain an offset(s) for a cell change (or handover or H/O) triggering measurement report (e.g., for A3 measurement condition) and an offset(s) for a system information (SI) triggering measurement report. At 310, the source cell may also determine or may receive an indication or identification (e.g., physical cell identifier or PCI) of one or more reconnection candidate cells for one or more source cells (e.g., reconnection candidate cell(s) for one or more specific source cells, regardless of the target cell), target cells (e.g., reconnection candidate cell(s), regardless of the source cell) and/or source cell/target cell combinations (or cell borders) (e.g., reconnection candidate cell(s) for one or more source/target cell combinations).

[0049] Source cell A may, for example, have obtained from an MRO entity, in advance, the information obtained at 310 (e.g. , offsets for measurement reports, and identification of reconnection candidate cells), for example. As noted, a reconnection candidate cell may be a cell that a user device may (e.g., may typically) reconnect to after a radio link failure (RLF), e.g., which may be based on statistics or historical behavior of user devices. For example, for a given source cell, a target cell and/or cell border (e.g., which may include a combination of a source cell and a target cell for a user device), there may be one or more reconnection candidate cells that most (or a significant percentage) of user devices may typically reconnect to after a RLF, e.g., before receiving a handover (H/O) command, or during other point. Therefore, according to an example implementation, it may be advantageous to pro-actively transmit the system information (SI) for a reconnection candidate cell to a user device, e.g., before the user device may typically need that system information (e.g., before a RLF for the user device).

[0050] Referring to FIG. 3, at 312, the source cell (source BS) A sends to user device 132 configuration information for the multiple measurement reports, such as an offset(s) for a handover triggering measurement report and an offset(s) for a SI triggering measurement report. A handover (or cell change) triggering measurement report is a signal measurement report that may trigger or cause the source cell to send a handover command to the user device to command a handover to a target cell. A SI triggering measurement report is a signal measurement report that may trigger or cause the source cell to send to the user device system information (SI) for one or more reconnection candidate cells. For example, for source cell A to which the user device is connected (or for a particular cell border where the user device is located), a first offset may be indicated for a H/O triggering measurement report and a second offset may be indicated for a SI triggering measurement report, wherein the first and second offsets are different and configured so as to cause the user device to send the SI triggering measurement report before sending the handover (or cell change) triggering measurement report. In this manner, by causing the source cell to send the SI of a reconnection candidate cell, the user device may already have the SI for the reconnection candidate cell in the event that a RLF failure occurs later on.

[0051] At 314, the user device 132 measures one or more signals, and determines that a measurement event has occurred or expired with respect to the offset for the system information. Therefore, at 314, the user device sends a SI triggering measurement report (e.g., for target cell B) to source cell A. As noted in 31 0, the source cell A may already have the PCI or identity of a reconnection candidate cell C associated with source cell A, target cell B and/or a cell border, for example. The source cell A may obtain, or may already have, the system information (SI) for the reconnection candidate cell C for the source cell A/target cell B. For example, at 316, the source cell A may send a H/O request to reconnection candidate cell C, indicating only a request for SI of cell C (thus, not really a H/O request, but only a request for SI of cell C). At 31 8, the source cell A may receive from reconnection candidate cell C the SI of cell C.

[0052] At 320, the source cell A sends the system information (SI) for reconnection candidate cell C to user device 132. This SI for reconnection candidate cell may be used by user device 132 to more quickly re-establish a cell connection to the reconnection candidate cell C in the event that a RLF occurs for the user device 132. The RLF may occur at various times or points. For example, at 322, before a handover command is received or even before a measurement event associated with a handover is even measured, the user device 132 may detect a RLF and then reestablish a connection to reconnection candidate cell C based on the previously received SI for cell C. For example, reconnection candidate cell C may be cell B (C=B in one example case).

[0053] Also, as another example, at 323 the user device may determine that a measurement event has occurred or expired associated with a handover to target cell B (e.g., signal strength of target cell B is greater than signal strength of source cell plus an offset), and then the user device 132 sends a cell change (or H/O) triggering measurement report (indicating target cell B for H/O). At 324, the user device may receive a cell change (or handover) command, indicating target cell B and providing the SI of target cell B. However, the SI of reconnection candidate cell (which may be a different cell than the source cell or the target cell) was previously received by the user device at 320. At 326, the user device, based on the previously received SI for the reconnection candidate cell C, re-establishes a connection to the reconnection candidate cell C, e.g., without waiting for the SI transmitted by the reconnection candidate cell C. Note, for example, that cell C could be 1 ) different than A and B (covering handover to wrong cell) or 2) different than B but same as A (covering too early handover). In the latter case (C=A), the source cell A would have sent proactively an up-to-date system information that may be used for reconnection in the event of RLF.

[0054] FIG. 4 is a diagram illustrating operation of a wireless network in which a user device receives system information for a reconnection candidate cell within a handover command to perform a handover to a target cell according to an example implementation. At 410, the source cell A may determine or obtain an offset(s) for a cell change (or handover or H/O) triggering measurement report (e.g., for A3 measurement condition). At 410, the source cell A may also determine or may receive an indication or identification (e.g., physical cell identifier or PCI) of one or more reconnection candidate cells for one or more source cells, target cell and/or source cell/target cell combinations (or cell borders).

[0055] Referring to FIG. 4, at 412, the source cell (source BS) A sends to user device 132 configuration information for the handover triggering measurement report. A handover (or cell change) triggering measurement report is a signal measurement report that may trigger or cause the source cell to send a handover command to the user device to command a handover to a target cell.

[0056] At 414, the user device may determine that a measurement event has occurred or expired associated with a handover to target cell B (e.g., signal strength of target cell B is greater than signal strength of source cell plus an offset), and then the user device 132 sends a cell change (or H/O) triggering measurement report (indicating target cell B for H/O), at 414.

[0057] At 416 and 41 8, the source cell request a H/O for user device 132 to target cell B, and target cell B may acknowledge or confirm the H/O and may provide SI for target cell B at 418. At 420, source cell A may request the SI (e.g., via H/O request) of reconnection candidate cell C, and may receive the SI of cell C at 422.

[0058] At 424, the user device 132 may receive a cell change (or handover) command from source cell A, indicating target cell B and providing the SI of reconnection candidate cell C. The H/O command received at 424 may also indicate the SI of target cell B. For example, the H/O command at 424 may indicate the PCI (physical cell identifier) and SI (system information) for target cell B, and the PCI and SI for reconnection candidate cell C.

[0059] At 426, the user device 132 may detect a RLF (e.g., after H/O to target cell B). After the RLF, the user device 132 may re-establish a connection to the reconnection candidate cell C, e.g., without waiting for the SI transmitted by the reconnection candidate cell C. For example, cell C may be cell A for the too early handover case, wherein for that case, source cell A can provide an updated SI to the user device via the handover command. In this manner, service interruption time after a RLF may be decreased for a user device.

[0060] FIG. 5 is a flow chart illustrating operation of a user device according to an example implementation. Operation 51 0 includes receiving, by a user device from a source cell in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell. Operation 520 includes measuring, by the user device, a received signal from each of a plurality of cells. Operation 530 includes determining that the first measurement event has occurred. Operation 540 includes sending, by the user device to the source cell, a system information triggering measurement report based on the occurrence of the first measurement event. Operation 550 includes receiving, by the user device from the source cell in response to sending the system information triggering measurement report, system information for at least the reconnection candidate cell. Operation 560 includes performing, by the user device based on a detection of a radio link failure for the user device, a connection re- establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0061] According to an example implementation of the method of FIG. 5, the reconnection candidate cell is the same as the target cell, and the system information for at least the reconnection candidate cell is received before the user device detects a radio link failure with respect to the source cell.

[0062] According to an example implementation of the method of FIG. 5, the system information for at least the reconnection candidate cell is received before determining, by the user device, that the second measurement event has occurred.

[0063] According to an example implementation of the method of FIG. 5, the reconnection candidate cell is different from the target cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell. [0064] According to an example implementation of the method of FIG. 5, wherein the reconnection candidate cell is different from the target cell and different from the source cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

[0065] According to an example implementation of the method of FIG. 5, and further including determining that the second measurement event has occurred; sending, by the user device to the source cell, a handover-triggering measurement report to the source cell based on the occurrence of the second measurement event; receiving, by the user device from the source cell in response to sending the handover-triggering measurement report, a handover command to command a handover of the user device to the target cell; performing a handover from the source cell to the target cell; and detecting a radio link failure with respect to the target cell; and wherein the performing a connection re-establishment comprises performing, by the user device based on the detection of the radio link failure, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0066] According to an example implementation of the method of FIG. 5, the configuration information may include: one or more offsets for the first measurement event; and one or more offsets for the second measurement event.

[0067] According to an example implementation of the method of FIG. 5, the first measurement event includes a first offset, and the second measurement event includes a second offset, wherein the first and second offsets are configured to cause the user device to determine an occurrence of the first measurement event before the second measurement event.

[0068] According to an example implementation of the method of FIG. 5, the configuration information for configuring the first measurement event may include a first offset, and wherein the configuration information for configuring the second measurement event comprises a second offset, wherein the first offset is based on the second offset to cause the user device to detect an occurrence of the first measurement event before detecting an occurrence of the second measurement event, based on a difference between the first offset and the second offset.

[0069] According to an example implementation of the method of FIG. 5, the system information received by the user device allows the user device to perform the connection re- establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[0070] According to an example implementation, an apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to: receive, by a user device from a source cell in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; measure, by the user device, a received signal from each of a plurality of cells; determine that the first measurement event has occurred; send, by the user device to the source cell, a system information triggering measurement report based on the occurrence of the first measurement event; receive, by the user device from the source cell in response to sending the system information triggering measurement report, system information for at least the reconnection candidate cell; and perform, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0071 ] According to an example implementation of the apparatus, the reconnection candidate cell is the same as the target cell, and the system information for at least the reconnection candidate cell is received before the user device detects a radio link failure with respect to the source cell.

[0072] According to an example implementation of the apparatus, the system information for at least the reconnection candidate cell is received before determining, by the user device, that the second measurement event has occurred.

[0073] According to an example implementation of the apparatus, the reconnection candidate cell is different from the target cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

[0074] According to an example implementation of the apparatus, wherein the reconnection candidate cell is different from the target cell and different from the source cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

[0075] According to an example implementation of the apparatus, and further including causing the apparatus to determine that the second measurement event has occurred; sending, by the user device to the source cell, a handover-triggering measurement report to the source cell based on the occurrence of the second measurement event; receiving, by the user device from the source cell in response to sending the handover-triggering measurement report, a handover command to command a handover of the user device to the target cell; performing a handover from the source cell to the target cell; and detecting a radio link failure with respect to the target cell; and wherein the performing a connection re-establishment comprises performing, by the user device based on the detection of the radio link failure, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0076] According to an example implementation of the apparatus, the configuration information may include: one or more offsets for the first measurement event; and one or more offsets for the second measurement event.

[0077] According to an example implementation of the apparatus, the first measurement event includes a first offset, and the second measurement event includes a second offset, wherein the first and second offsets are configured to cause the user device to determine an occurrence of the first measurement event before the second measurement event.

[0078] According to an example implementation of the apparatus, the configuration information for configuring the first measurement event may include a first offset, and wherein the configuration information for configuring the second measurement event comprises a second offset, wherein the first offset is based on the second offset to cause the user device to detect an occurrence of the first measurement event before detecting an occurrence of the second measurement event, based on a difference between the first offset and the second offset.

[0079] According to an example implementation of the apparatus, the system information received by the user device allows the user device to perform the connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[0080] FIG. 6 is a flow chart illustrating operation of a cell or base station according to an example implementation. Operation 61 0 includes sending, by a source cell to a user device in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell. Operation 620 includes receiving, by the source cell from the user device, a system information triggering measurement report based on an occurrence of the first measurement event. Operation 630 includes obtaining, by the source cell from the reconnection candidate cell, system information for the reconnection candidate cell. Operation 640 includes sending, by the source cell to the user device in response to receiving the system information triggering measurement report, the system information for the reconnection candidate cell.

[0081] According to an example implementation of the method of FIG. 6, and further including obtaining, by the source cell from a mobility robustness optimization (MRO) entity, one or more offsets for the first measurement event, and one or more offsets for the second measurement event, for one or more reconnection candidate cells or target cells.

[0082] According to an example implementation of the method of FIG. 6, the reconnection candidate cell is the same as the target cell, and the system information for at least the reconnection candidate cell is received before the user device detects a radio link failure with respect to the source cell.

[0083] According to an example implementation of the method of FIG. 6, the system information for at least the reconnection candidate cell is received before determining, by the user device, that the second measurement event has occurred.

[0084] According to an example implementation of the method of FIG. 6, the reconnection candidate cell is different from the target cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

[0085] According to an example implementation of the method of FIG. 6, the configuration information may include: one or more offsets for the first measurement event; and one or more offsets for the second measurement event. [0086] According to an example implementation of the method of FIG. 6, the first measurement event includes a first offset, and the second measurement event includes a second offset, wherein the first and second offsets are configured to cause the user device to determine an occurrence of the first measurement event before the second measurement event.

[0087] According to an example implementation of the method of FIG. 6, the configuration information for configuring the first measurement event may include a first offset, and wherein the configuration information for configuring the second measurement event comprises a second offset, wherein the first offset is based on the second offset to cause the user device to detect an occurrence of the first measurement event before detecting an occurrence of the second measurement event, based on a difference between the first offset and the second offset.

[0088] An apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to send, by a source cell to a user device in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell; receive, by the source cell from the user device, a system information triggering measurement report based on an occurrence of the first measurement event; obtain, by the source cell from the reconnection candidate cell, system information for the reconnection candidate cell; and send, by the source cell to the user device in response to receiving the system information triggering measurement report, the system information for the reconnection candidate cell.

[0089] According to an example implementation of the apparatus, and further causing the apparatus to obtain, by the source cell from a mobility robustness optimization (MRO) entity, one or more offsets for the first measurement event, and one or more offsets for the second measurement event, for one or more reconnection candidate cells or target cells.

[0090] According to an example implementation of the apparatus, the reconnection candidate cell is the same as the target cell, and the system information for at least the reconnection candidate cell is received before the user device detects a radio link failure with respect to the source cell.

[0091] According to an example implementation of the apparatus, the system information for at least the reconnection candidate cell is received before determining, by the user device, that the second measurement event has occurred.

[0092] According to an example implementation of the apparatus, the reconnection candidate cell is different from the target cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

[0093] According to an example implementation of the apparatus, the configuration information may include: one or more offsets for the first measurement event; and one or more offsets for the second measurement event. [0094] According to an example implementation of the apparatus, the first measurement event includes a first offset, and the second measurement event includes a second offset, wherein the first and second offsets are configured to cause the user device to determine an occurrence of the first measurement event before the second measurement event.

[0095] According to an example implementation of the apparatus, the configuration information for configuring the first measurement event may include a first offset, and wherein the configuration information for configuring the second measurement event comprises a second offset, wherein the first offset is based on the second offset to cause the user device to detect an occurrence of the first measurement event before detecting an occurrence of the second measurement event, based on a difference between the first offset and the second offset.

[0096] FIG. 7 is a flow chart illustrating operation of a user device according to another example implementation. Operation 71 0 includes sending, by a user device to a source cell, a measurement report indicating a handover to a target cell. Operation 720 includes receiving, by the user device from the source cell, a message including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell. And, operation 730 includes performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[0097] According to an example implementation of the method of FIG. 7, the message further includes system information for the target cell.

[0098] According to an example implementation of the method of FIG. 7, the reconnection candidate cell is different from the target cell, and the system information for the reconnection candidate cell is received before the radio link failure of the user device.

[0099] According to an example implementation of the method of FIG. 7, the system information for a cell reconnection candidate cell allows the user device to perform the connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[00100] An apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to send, by a user device to a source cell, a measurement report indicating a handover to a target cell; receive, by the user device from the source cell, a message including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell; perform, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

[00101] According to an example implementation of the apparatus, the message further includes system information for the target cell.

[00102] According to an example implementation of the apparatus, the reconnection candidate cell is different from the target cell, and the system information for the reconnection candidate cell is received before the radio link failure of the user device. [00103] According to an example implementation of the apparatus, the system information for a cell reconnection candidate cell allows the user device to perform the connection re- establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[00104] FIG. 8 is a flow chart illustrating operation of a cell or base station according to another example implementation. Operation 81 0 includes receiving, by a source cell from a user device, a measurement report indicating a handover to a target cell. Operation 820 includes making a handover decision to perform a handover of the user device to the target cell. Operation 830 includes sending, by the source cell to the user device, a message including a handover command for the user device to perform a handover to the target cell, and system information for a reconnection candidate cell, wherein the system information allows the user device to perform a connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[00105] According to an example implementation of the method of FIG. 8, the message further includes system information for the target cell. Further illustrative details will now be provided.

[00106] An apparatus includes at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to receive, by a source cell from a user device, a measurement report indicating a handover to a target cell; make a handover decision to perform a handover of the user device to the target cell; and send, by the source cell to the user device, a message including a handover command for the user device to perform a handover to the target cell, and system information for a reconnection candidate cell, wherein the system information allows the user device to perform a connection re- establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

[00107] According to an example implementation of the apparatus, the message further includes system information for the target cell. Further illustrative details will now be provided.

[00108] According to an example implementation, the network (e.g., a cell or BS) makes use of the information gathered from Mobility Robustness Optimization (MRO) procedure (or MRO entity) to transmit proactively to some user devices/UEs part of the handover command that contains the access related information of neighboring target cell(s), which may be referred to as reconnection candidate cells, that are relevant for connection re-establishment before any cell change (or H/O) occurs, for example.

[00109] A number of different features may be provided, according to various example implementations, for example:

[00110] A MRO entity may be used to determine the source cells that are responsible for RLFs and which shall apply the proactive transmission of SI for one or more reconnection candidate cells. As such, the proactive transmission is not executed by all cells of the network, rather by only a relatively small subset of the cells in the network which have RLFs occurring with respect to neighboring target cells. [00111 ] MRO entity may be used as well to determine for which neighboring target cells (or reconnection candidate cells) the proactive transmission of the SI shall be performed. For instance, in case of too late handovers occurring on a cell-pair specific border between the source and a neighboring target cell, the SI that is proactively forwarded may, for example, pertain to that specific neighboring target cell (reconnection candidate cell) that the user device/UE reconnect to after RLF. If the RLFs are deemed by MRO entity to be too-early handovers or handover to wrong cell, the SI that is proactively forwarded should pertain to target cell (or reconnection candidate cell) that the user devices/UEs reconnect to after being handed over. In the case too late and too- early/handover to wrong cell occur on the same cell-pair specific border, e.g., user devices/UEs moving on two streets crossing the same source and neighboring cell border have different types of mobility failures, the SI that is proactively forwarded should pertain to target cell candidates (reconnection candidate cells) that the U E might reconnect to in case of too late or too early/handover to wrong cell. This is because the mobility parameters e.g., Cell Individual Offset (CIO), in current 3GPP specifications are configured cell-pair specific and cannot typically differentiate between locations, for example.

[00112] By, for example, using the mobility parameters (e.g., offsets) optimized by MRO entity, the network (e.g., cells or BSs) can configure the user device/UE with an event-based trigger for providing proactively the SI of neighboring target and which expires (or event occurs) before any cell change occurs. Thus, in this case, the SI may, for example, be provided only for the relevant user devices/UEs that are about to experience a cell change either by handover or an RLF.

Specifically, two different A3 triggers can be configured, an early one to trigger the SI transmission (for SI information of a reconnection candidate cell), and the conventional later A3 trigger to trigger the cell change (and potentially provide an up-to-date SI).

[00113] In the case the mobility failures occurring with respect to a neighboring target cell are deemed by MRO entity to be either too-early or handover to wrong cell, the source cell can send the SI of target cell C (or reconnection candidate cell C) to which the user device/UE would re-connect to after RLF during the handover preparation/execution phase, i.e., could be part of the handover command, instead of using an event-based trigger. That is the SI of the target cell C (reconnection candidate cell C) to which the user device/UE might re-connect to after RLF is transmitted during the handover procedure in addition to the SI of target cell B to which the user device/UE is being handed over.

[00114] This pro-active delivery of SI may use the shared channel (i.e. dedicated signaling) which may be more efficient than broadcasting.

[00115] Finally, a finer optimization may be performed by providing the SI (of the reconnection candidate cell) to only the user devices which are at risk to have mobility failures. In a simple case, the SI of a reconnection candidate cell may only be provided to U Es with a specific mobility status (or mobility information), e.g., only to fast user devices/UEs.

[00116] For intra-frequency handovers in LTE, as an illustrative example, an example trigger for a measurement report is the A3 trigger which may be defined as follows (simplified):

[00117] Mn + Ocn > Ms + Off [00118] This event or trigger occurs or expires if the measurement Mn of a neighbor cell n is offset Off better than the measurement Ms of a serving (or source) cell. The measurements could be given as signal strength (RSRP) or as a signal quality (RSRQ).

[00119] The offset Off introduces a kind of hysteresis to the handover decision to avoid ping-pongs. Ocn is another offset a.k.a Cell Individual Offset which, in contrast to Off, is neighbor- specific. It can be used to fine-adjust the handovers individually towards different neighbors due to mobility robustness reasons, e.g., make the neighbor more attractive if it is entered through a highspeed street.

[00120] For providing proactively the SI of neighboring target cell (reconnection candidate cell), the network (e.g., cell or BS) can configure the user device/UE with another event that is A3- like (and causing the transmission of a system information triggering measurement report, and/or associated with or causing the transmission of SI for a reconnection candidate cell). This Sl-related event can be configured to expire before any cell change , e.g., when a cell change would be too early/too risky, by configuring Ocn or Off to be offset X higher or lower, respectively, than those used by MRO entity for the A3 (H/O-related) event. For instance, assume that Off is configured to 3 dB and Ocn = 1 dB with respect to neighboring cell n. In this case, the measurement event A3 (H/O-related event) expires when Mn > Ms + 2 dB. The parameters of the new event (Sl-related event) could be configured for instance as follows: Ocn' = Ocn + X dB where X is set to e.g. 4 dB. In this case, the new event (Sl-related event) expires before the A3 (H/O-related) event when Mn > Ms - 2 dB.

[00121] In case of the expiration or occurrence of the new (Sl-related) event, the user device/UE informs the network and sends the measurement report (e.g. , sends the SI triggering measurement report to the serving/source cell). Upon receiving the measurement report, the network or source cell/serving cell transmits to the user device/UE the SI of the relevant neighboring target cell (or reconnection candidate cell) as determined by MRO entity, for example. The source/serving cell may send as well the Physical Cell Identity (PCI) of the neighboring cell (reconnection candidate cell) for which the delivered SI belongs to. The user device/UE may derive the PCI from downlink synchronization and use it to associate the selected neighboring target cell (reconnection candidate cell) for connection re-establishment with the corresponding acquired SI.

[00122] In case the actual cell change (H/O) should be too late and an RLF occurs, the user device/UE has received already the SI from the source cell for the reconnection candidate cell, and thus, saves (e.g., avoids or is able to omit) a dominant part of T target (see FIG.. 2), and thereby reduces service interruption time after an RLF.

[00123] According to an example implementation, the source/serving cell may send a request for the target neighboring cell (reconnection candidate cell) to deliver or provide the SI of the reconnection candidate cell, even though there is no UE that is being handed over. Thus, the H/O request may include a parameter that indicates only SI request (not actually a H/O request). The H/O - SI only request may, for example, be sent upon the reception of the measurement report from the UE (corresponding to the new configured event associated with SI) or performed beforehand. Such a procedure may be based on the current cell preparation procedure. In principle, this could be already done with today's procedure (a preparation does not necessarily require a cell change and multiple cells can be prepared), however it would be advantageous to modify this procedure: UE context does not need to be exchanged at this stage. With the current cell preparation, the target cell has to assume that the UE will perform handover to the target cell, i.e., target cell will typically reserve resources in response to H/O request. However, with this proactive SI exchange, the target cell (reconnection candidate cell) should be made aware (e.g., that this is just a SI request, not a standard H/O request), and therefore, no resources have to be reserved yet at the reconnection candidate cell for a H/O-SI only request received via 316 and 420, for example (FIGs. 3-4). Also, there may be several possible reconnection candidate cells for a user device/UE, and thus, SI information may be sent to the user device for multiple reconnection candidate cells.

[00124] FIG. 9 is a block diagram of a wireless station (e.g., AP or user device) 900 according to an example implementation. The wireless station 900 may include, for example, one or two RF (radio frequency) or wireless transceivers 902A, 902B, where each wireless transceiver includes a transmitter to transmit signals and a receiver to receive signals. The wireless station also includes a processor or control unit/entity (controller) 904 to execute instructions or software and control transmission and receptions of signals, and a memory 906 to store data and/or instructions.

[00125] Processor 904 may also make decisions or determinations, generate frames, packets or messages for transmission, decode received frames or messages for further processing, and other tasks or functions described herein. Processor 904, which may be a baseband processor, for example, may generate messages, packets, frames or other signals for transmission via wireless transceiver 902 (902A or 902B). Processor 904 may control transmission of signals or messages over a wireless network, and may control the reception of signals or messages, etc., via a wireless network (e.g., after being down-converted by wireless transceiver 902, for example). Processor 904 may be programmable and capable of executing software or other instructions stored in memory or on other computer media to perform the various tasks and functions described above, such as one or more of the tasks or methods described above.

Processor 904 may be (or may include), for example, hardware, programmable logic, a programmable processor that executes software or firmware, and/or any combination of these. Using other terminology, processor 904 and transceiver 902 together may be considered as a wireless transmitter/receiver system, for example.

[00126] In addition, referring to FIG. 9, a controller (or processor) 908 may execute software and instructions, and may provide overall control for the station 900, and may provide control for other systems not shown in FIG. 9, such as controlling input/output devices (e.g., display, keypad), and/or may execute software for one or more applications that may be provided on wireless station 900, such as, for example, an email program, audio/video applications, a word processor, a Voice over IP application, or other application or software.

[00127] In addition, a storage medium may be provided that includes stored instructions, which when executed by a controller or processor may result in the processor 904, or other controller or processor, performing one or more of the functions or tasks described above.

[00128] According to another example implementation, RF or wireless transceiver(s) 902A/902B may receive signals or data and/or transmit or send signals or data. Processor 904 (and possibly transceivers 902A/902B) may control the RF or wireless transceiver 902A or 902B to receive, send, broadcast or transmit signals or data.

[00129] The embodiments are not, however, restricted to the system that is given as an example, but a person skilled in the art may apply the solution to other communication systems. Another example of a suitable communications system is the 5G concept. It is assumed that network architecture in 5G will be quite similar to that of the LTE-advanced. 5G is likely to use multiple input - multiple output ( IMO) antennas, many more base stations or nodes than the LTE (a so-called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

[00130] It should be appreciated that future networks will most probably utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into "building blocks" or entities that may be operationally connected or linked together to provide services. A virtualized network function (VN F) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations may be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent.

[00131] Implementations of the various techniques described herein may be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. Implementations may be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device or in a propagated signal, for execution by, or to control the operation of, a data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. Implementations may also be provided on a computer readable medium or computer readable storage medium, which may be a non-transitory medium. Implementations of the various techniques may also include implementations provided via transitory signals or media, and/or programs and/or software implementations that are downloadable via the Internet or other network(s), either wired networks and/or wireless networks. In addition, implementations may be provided via machine type communications ( TC), and also via an Internet of Things (IOT).

[00132] The computer program may be in source code form, object code form, or in some intermediate form, and it may be stored in some sort of carrier, distribution medium, or computer readable medium, which may be any entity or device capable of carrying the program. Such carriers include a record medium, computer memory, read-only memory, photoelectrical and/or electrical carrier signal, telecommunications signal, and software distribution package, for example. Depending on the processing power needed, the computer program may be executed in a single electronic digital computer or it may be distributed amongst a number of computers.

[00133] Furthermore, implementations of the various techniques described herein may use a cyber-physical system (CPS) (a system of collaborating computational elements controlling physical entities). CPS may enable the implementation and exploitation of massive amounts of interconnected ICT devices (sensors, actuators, processors microcontrollers,...) embedded in physical objects at different locations. Mobile cyber physical systems, in which the physical system in question has inherent mobility, are a subcategory of cyber-physical systems. Examples of mobile physical systems include mobile robotics and electronics transported by humans or animals. The rise in popularity of smartphones has increased interest in the area of mobile cyber-physical systems. Therefore, various implementations of techniques described herein may be provided via one or more of these technologies.

[00134] A computer program, such as the computer program(s) described above, can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit or part of it suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[00135] Method steps may be performed by one or more programmable processors executing a computer program or computer program portions to perform functions by operating on input data and generating output. Method steps also may be performed by, and an apparatus may be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[00136] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer, chip or chipset. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. Elements of a computer may include at least one processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer also may include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and the memory may be supplemented by, or incorporated in, special purpose logic circuitry.

[00137] To provide for interaction with a user, implementations may be implemented on a computer having a display device, e.g., a cathode ray tube (CRT) or liquid crystal display (LCD) monitor, for displaying information to the user and a user interface, such as a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input.

[00138] Implementations may be implemented in a computing system that includes a back-end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front-end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an

implementation, or any combination of such back-end, middleware, or front-end components. Components may be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network (LAN) and a wide area network (WAN), e.g., the Internet.

[00139] While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the various embodiments.

Claims

WHAT IS CLAIMED IS:

1 . A method comprising:

receiving, by a user device from a source cell in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell;

measuring, by the user device, a received signal from each of a plurality of cells;

determining that the first measurement event has occurred;

sending, by the user device to the source cell, a system information triggering measurement report based on the occurrence of the first measurement event;

receiving, by the user device from the source cell in response to sending the system information triggering measurement report, system information for at least the reconnection candidate cell; and

performing, by the user device based on a detection of a radio link failure for the user device, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

2. The method of claim 1 wherein the reconnection candidate cell is the same as the target cell, and the system information for at least the reconnection candidate cell is received before the user device detects a radio link failure with respect to the source cell.

3. The method of any of claims 1 -2 wherein the system information for at least the reconnection candidate cell is received before determining, by the user device, that the second measurement event has occurred.

4. The method of any of claims 1 -3 wherein the reconnection candidate cell is different from the target cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

5. The method of any of claims 1 -4 wherein the reconnection candidate cell is different from the target cell and different from the source cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

6. The method of any of claims 1 -5 and further comprising:

determining that the second measurement event has occurred; sending, by the user device to the source cell, a handover-triggering measurement report to the source cell based on the occurrence of the second measurement event; and

receiving, by the user device from the source cell in response to sending the handover- triggering measurement report, a handover command to command a handover of the user device to the target cell;

performing a handover from the source cell to the target cell; and

detecting a radio link failure with respect to the target cell; and

wherein the performing a connection re-establishment comprises performing, by the user device based on the detection of the radio link failure, a connection re-establishment with the reconnection candidate cell using the received system information for the reconnection candidate cell.

7. The method of any of claims 1 -6 wherein the configuration information comprises: one or more offsets for the first measurement event; and

one or more offsets for the second measurement event.

8. The method of any of claims 1 -7 wherein the first measurement event includes a first offset, and the second measurement event includes a second offset, wherein the first and second offsets are configured to cause the user device to determine an occurrence of the first measurement event before the second measurement event.

9. The method of any of claims 1 -8 wherein the configuration information for configuring the first measurement event comprises a first offset, and wherein the configuration information for configuring the second measurement event comprises a second offset, wherein the first offset is based on the second offset to cause the user device to detect an occurrence of the first measurement event before detecting an occurrence of the second measurement event, based on a difference between the first offset and the second offset.

10. The method of any of claims 1 -9 wherein the system information received by the user device allows the user device to perform the connection re-establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

1 1 . An apparatus comprising means for performing a method of any of claims 1 -10.

12. A computer program product comprising a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method of any of claims 1 -10.

13. An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform a method of any of claims 1 -1 0.

14. A method comprising:

sending, by a source cell to a user device in a wireless network, configuration information for configuring a first measurement event and a second measurement event, an occurrence of the first measurement event associated with triggering a transmission from the source cell to the user device of system information for a reconnection candidate cell, and an occurrence of the second measurement event associated with triggering a transmission from the source cell to the user device of a handover command to command a handover of the user device to a target cell;

receiving, by the source cell from the user device, a system information triggering measurement report based on an occurrence of the first measurement event;

obtaining, by the source cell from the reconnection candidate cell, system information for the reconnection candidate cell;

sending, by the source cell to the user device in response to receiving the system information triggering measurement report, the system information for the reconnection candidate cell.

15. The method of claim 14 and further comprising:

obtaining, by the source cell from a mobility robustness optimization (MRO) entity, one or more offsets for the first measurement event, and one or more offsets for the second measurement event, for one or more reconnection candidate cells or target cells.

16. The method of any of claims 14-15 wherein the reconnection candidate cell is the same as the target cell, and the system information for at least the reconnection candidate cell is received before the user device detects a radio link failure with respect to the source cell.

17. The method of any of claims 14-16 wherein the system information for at least the reconnection candidate cell is received before determining, by the user device, that the second measurement event has occurred.

18. The method of any of claims 14-17 wherein the reconnection candidate cell is different from the target cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

19. The method of any of claims 14-18 wherein the reconnection candidate cell is different from the target cell and different from the source cell, and the system information for at least the reconnection candidate cell is received before a handover of the user device to the target cell.

20. The method of any of claims 14-19 wherein the configuration information comprises: one or more offsets for the first measurement event; and

one or more offsets for the second measurement event.

21 . The method of any of claims 14-20 wherein the first measurement event includes a first offset, and the second measurement event includes a second offset, wherein the first and second offsets are configured to cause the user device to determine an occurrence of the first measurement event before the second measurement event.

22. The method of any of claims 14-21 wherein the configuration information for configuring the first measurement event comprises a first offset, and wherein the configuration information for configuring the second measurement event comprises a second offset, wherein the first offset is based on the second offset to cause the user device to detect an occurrence of the first measurement event before detecting an occurrence of the second measurement event, based on a difference between the first offset and the second offset.

23. An apparatus comprising means for performing a method of any of claims 14-22.

24. A computer program product comprising a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method of any of claims 14-22.

25. An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform a method of any of claims 14-22.

26. A method comprising:

sending, by a user device to a source cell, a measurement report indicating a handover to a target cell;

receiving, by the user device from the source cell, a message including a handover command for the user device to perform a handover to the target cell, and system information for a cell reconnection candidate cell; and

27. The method of claim 26 wherein the message further includes system information for the target cell.

28. The method of any of claims 26-27 wherein the reconnection candidate cell is different from the target cell, and the system information for the reconnection candidate cell is received before the radio link failure of the user device.

29. The method of any of claims 26-28 wherein the reconnection candidate cell is different from the target cell and different from the source cell, and the system information for the reconnection candidate cell is received before the radio link failure of the user device.

30. The method of any of claims 26-29 wherein the system information for a cell reconnection candidate cell allows the user device to perform the connection re- establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

31 . An apparatus comprising means for performing a method of any of claims 26-30.

32. A computer program product comprising a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method of any of claims 26-30.

33. An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform a method of any of claims 26-30.

34. A method comprising:

receiving, by a source cell from a user device, a measurement report indicating a handover to a target cell;

making a handover decision to perform a handover of the user device to the target cell; sending, by the source cell to the user device, a message including a handover command for the user device to perform a handover to the target cell, and system information for a reconnection candidate cell;

wherein the system information allows the user device to perform a connection re- establishment with the reconnection candidate cell without receiving or waiting to receive the system information that is periodically transmitted from the reconnection candidate cell.

35. The method of claim 34 wherein the message further includes system information for the target cell.

36. An apparatus comprising means for performing a method of any of claims 34-35.

37. A computer program product comprising a computer-readable storage medium and storing executable code that, when executed by at least one data processing apparatus, is configured to cause the at least one data processing apparatus to perform a method of any of claims 34-35.

38. An apparatus comprising at least one processor and at least one memory including computer instructions, when executed by the at least one processor, cause the apparatus to perform a method of any of claims 34-35.