WO2018197097A1 - Temporisateur permettant une mobilité autonome d'un dispositif de communication dans des réseaux cellulaires - Google Patents

Temporisateur permettant une mobilité autonome d'un dispositif de communication dans des réseaux cellulaires Download PDF

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Publication number
WO2018197097A1
WO2018197097A1 PCT/EP2018/056180 EP2018056180W WO2018197097A1 WO 2018197097 A1 WO2018197097 A1 WO 2018197097A1 EP 2018056180 W EP2018056180 W EP 2018056180W WO 2018197097 A1 WO2018197097 A1 WO 2018197097A1
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WIPO (PCT)
Prior art keywords
communication device
network
information
timer
handover
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PCT/EP2018/056180
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English (en)
Inventor
Elena Virtej
Jari Petteri Lunden
Frank Frederiksen
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Nokia Technologies Oy
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Publication of WO2018197097A1 publication Critical patent/WO2018197097A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/24—Reselection being triggered by specific parameters
    • H04W36/249—Reselection being triggered by specific parameters according to timing information
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/0005—Control or signalling for completing the hand-off
    • H04W36/0083—Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
    • H04W36/00837—Determination of triggering parameters for hand-off
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/14—Reselecting a network or an air interface
    • H04W36/144—Reselecting a network or an air interface over a different radio air interface technology
    • H04W36/1443—Reselecting a network or an air interface over a different radio air interface technology between licensed networks
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/34—Reselection control
    • H04W36/36—Reselection control by user or terminal equipment
    • H04W36/362—Conditional handover

Definitions

  • the present invention relates to t e field of wireless communications. More specifically, the present invention relates to methods, apparatus, systems and computer programs for controlling a timer triggering autonomous handover of a communication device in a cellular network operated on license-exempt radio spectrum.
  • a communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path.
  • a communication system can be provided for example by means of a communication network and one or more compatible communication devices.
  • the communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and/or content data and so on.
  • Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.
  • a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link.
  • wireless systems comprise public land mobile networks (PLMN), satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN).
  • the wireless systems can typically be divided into cells, and are therefore often referred to as cellular systems.
  • a user can access the communication system by means of an appropriate communication device or terminal.
  • a communication device of a user is often referred to as user equipment (UE).
  • UE user equipment
  • a communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users.
  • the communication device may access a carrier provided by a station, for example a base station of a cell, and transmit and/or receive communications on the carrier.
  • the communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters, which shall be used for the connection are also typically defined.
  • LTE long-term evolution
  • UMTS Universal Mobile Telecommunications System
  • Communication systems may be configured to use a mechanism for aggregating radio carriers to support wider transmission bandwidth.
  • this mechanism is referred to as carrier aggregation (CA).
  • a communication device with reception and/or transmission capabilities for CA can simultaneously receive and/or transmit on multiple component carriers (CCs) corresponding to multiple serving cells, for which the communication device has acquired/monitors system information needed for initiating connection establishment.
  • CCs component carriers
  • Communication systems may be configured to support simultaneous communication with two or more access nodes.
  • this mechanism is referred to as dual connectivity (DC).
  • a communication device may be configured in LTE to communicate with a master eNB (MeNB) and a secondary eNB (SeNB).
  • the MeNB may typically provide access to a macrocell, while the SeNB may provide on a different radio carrier access to a relatively small cell, such as a picocell.
  • Future networks, such as 5G may progressively integrate data transmissions of different radio technologies in a communication between one or more access nodes and a communication device.
  • communication devices may be able to operate simultaneously on more than one radio access technology, and carrier aggregation and dual connectivity may not be limited to the use of radio carriers of only one radio access technology. Rather, aggregation of radio carriers according to different radio access technologies and concurrent communication on such aggregated carriers may be supported.
  • Small cells such as picocells
  • Integration of radio access technologies and/or a high number of small cells may bring about that a communication device may detect more and more cells in future networks, which are suitable candidates for connection establishment.
  • Enhancements of carrier aggregation and dual connectivity mechanisms may be needed to make best use of these cells in future radio access networks.
  • Such enhancements may allow for an aggregation of a high number of radio carriers at a communication device, and in particular an integration of radio carriers operated on license- exempt (sometimes referred to as unlicensed) radio spectrum.
  • Wireless communication systems may be licensed to operate in particular spectrum bands.
  • a technology for example LTE, may operate, in addition to a licensed band, in a license-exempt band.
  • LTE operation in the license-exempt spectrum may be based on the LTE Carrier Aggregation (CA) framework where one or more low power secondary cells (SCells) operate in the license-exempt spectrum (sometimes referred to as unlicensed radio spectrum) and may be either downlink- only or contain both uplink (UL) and downlink (DL), and where the primary cell (PCell) operates in the licensed spectrum and can be either LTE Frequency Division Duplex (FDD) or LTE Time Division Duplex (TDD).
  • CA LTE Carrier Aggregation
  • SCells low power secondary cells
  • FDD Frequency Division Duplex
  • TDD Time Division Duplex
  • LTE-LAA LTE Licensed-Assisted Access
  • LTE-U LTE in Unlicensed Spectrum
  • LAA-LAA LTE Licensed-Assisted Access
  • LTE-U LTE in Unlicensed Spectrum
  • the licensed and license-exempt bands may be operated together using, e.g., carrier aggregation or dual connectivity. For example, carrier aggregation between a primary cell (PCell) on a licensed band and one or more secondary cells (SCells) on license-exempt band may be applied, and uplink control information of the SCells may be communicated in the PCell on licensed spectrum.
  • PCell primary cell
  • SCells secondary cells
  • license-exempt carriers may be used for stand-alone operation on license-exempt spectrum.
  • a technology for standalone operation at least some of the functions for access to cells on license-exempt spectrum and data transmission in these cells are performed without or with only minimum assistance or signaling support from license-based spectrum.
  • An example of such a stand-alone system is known as MulteFire, which utilizes LTE-based radio technology on license-exempt radio spectrum.
  • License-exempt band technologies may need to abide by certain rules, e.g. a clear channel assessment procedure, such as Listen-Before-Talk (LBT), in order to provide fair coexistence between LTE and other technologies such as Wi-Fi as well as between LTE operators.
  • LBT Listen-Before-Talk
  • a user or an access point may, depending on rules or regulatory requirements, need to perform a Clear Channel
  • CCA Listen-Before-Talk
  • LBT Listen-Before-Talk
  • the user or access node may, for example, monitor a given radio frequency, i.e. carrier, for a short period of time to ensure that the spectrum is not already occupied by some other transmission.
  • CCA procedures such as LBT, may be needed in order to guarantee co-existence with other license-exempt band usage in order to enable e.g. fair co-existence with Wi-Fi also operating on the same spectrum and/or carriers.
  • the user or access point is allowed to start transmission within a transmission opportunity.
  • the maximum duration of the transmission opportunity may be preconfigured or may be signaled in the system.
  • the use of CCA procedures in a radio access technology causes uncertainty about the times when signals are being transmitted in a wireless network. This uncertainty will compromise the reliability of time-critical control procedures, such as the handover procedure, in a wireless network.
  • the serving eNB can control the mobility of a communication device by directing handover using radio resources that are guaranteed to be available for that handover and coordinated with a designed target eNB for that purpose. This allows execution of pure network-controlled (NW-controlled) handover in a licensed radio environment.
  • NW-controlled handover of a communication device may be complemented by a handover procedure, which is more under control of the communication device.
  • This additional type of handover is in the following referred to as autonomous UE mobility (AUM) handover.
  • AUM autonomous UE mobility
  • the autonomous handover could be as well happen without any NW-controlled procedure, if a communication device is pre-configured by network to do so.
  • a network controlled handover could operate as a fallback-mode or vice- versa (i.e. a network-controlled handover may also be a viable operation mode in an unlicensed frequency band as well).
  • the overall concept of AUM is to provide means for the network to pre-configure devices such that they may be able to autonomously connect to neighboring cells, thereby allowing for faster handover procedures in case of the radio link failing. This feature is mainly driven by the fact that using LTE technology in unlicensed bands will cause uncertainty related to access to transmission on the radio channel.
  • This uncertainty is present for both downlink transmissions from the eNB (needed for radio link monitoring and transmission of control messages) and for the uplink transmissions from the UEs (needed for transmission of measurement reports).
  • a UE starts experiencing poor channel and link quality, this can be caused by either lack of coverage or lack of signals for measurements. The latter will be the case whenever the radio channel is busy (highly occupied), and this will also cause challenges for the UE to deliver normal measurement reports to indicate that a neighboring cell may provide better conditions.
  • Figure 3 illustrates an example problem autonomous UE mobility (AUM) presents.
  • the UE 10 has an active radio connection with the serving eNB 20S (access node of the serving cell).
  • the serving eNB 20S may obtain information about a declining quality of signals from/to this UE 10 and from this it might anticipate the UE may soon need to handover, but the UE's mobility in this radio environment is configured to be in an autonomous manner, so the serving eNB 20S cannot direct such a handover. In other words, the network cannot control when or where the UE will do the actual handover.
  • the UE may choose to relocate to another cell, for example, the UE may consider the channel with the serving eNB 20S is too busy or there are insufficient signals for measuring the channel (e.g. due to high blocking of the channel, UE cannot detect receive/transmit in downlink/uplink). From the network's perspective the timing of a handover is more variable when the UE has autonomous mobility.
  • the timing of a handover is more variable when the UE has autonomous mobility.
  • the UE can choose either, and so in certain instances from the network's perspective the mobility target of a handover is more variable when the UE has autonomous mobility.
  • AUM handover requires either costly pre- configuration of the communication device including allocation of certain resources in potential target cells, or fast context fetch by the target cell from the source cell, if the target cell is not prepared for accommodating the communication device. Therefore, it may be beneficial to avoid AUM handover and perform NW-controlled handover, if possible.
  • a means for controlling preference of NW-controlled handover over AUM handover is a timer, in the following referred to as AUM timer. The AUM timer may be started once a
  • the communication device only if the AUM timer expires before a NW-controlled handover of the communication device has succeeded.
  • the setting of the AUM timer controls for how long AUM handover of a communication device is delayed after detection of a handover event.
  • the communication device may trigger autonomously the handover to the target eNB, if the communication device is configured to do so. Therefore, there is a need for appropriate setting of the AUM timer's start value and potential adjustments of the running AUM timer when new information related to the handover procedure gets available at the communication device.
  • a method comprising detecting at a communication device a measurement event in a network; initiating, triggered by the measurement event, transmission of a measurement report to the network for network-controlled handover of the communication device; starting, triggered by the measurement event, a timer; waiting for a handover command from the network instructing the communication device to perform handover to a network-selected target cell; initiating transmission of a handover request message to a device-selected target cell, if the timer expires before the handover command is received at the communication device transmission; and adjusting the time until expiry of the started timer based on adjustment information obtained at the communication device, wherein the adjustment information is indicative of a probability for receiving the handover command before a radio link failure at the communication device occurs.
  • the adjustment information may comprise progress information from the network indicative of a progress of the network-controlled handover.
  • the progress information may comprise information acknowledging reception of the measurement report at an access node of the network.
  • the progress information may comprise time information indicative of the time when the measurement report was received at the access node.
  • the adjusting the time until expiry of the timer may comprise reducing the time, if the progress information indicates too slow progress of the network-controlled handover.
  • the progress information may indicate too slow progress of the network-controlled handover, if the information acknowledging reception of the measurement report was received after a predetermined upper time threshold for acknowledging the measurement report.
  • the progress information may indicate too slow progress of the network-controlled handover, if the information indicative of the time when the measurement report was received at the access node exceeds a predetermined upper time threshold for receiving the measurement report.
  • the adjusting the time until expiry of the timer may comprise extending the time until expiry of the timer, if the progress information indicates sufficient progress of the network-controlled handover.
  • the progress information may indicate sufficient progress of the network controlled handover, if the information acknowledging reception of the measurement report was received before a predetermined lower time threshold for acknowledging the measurement report.
  • the progress information may indicate sufficient progress of the network controlled handover, if the information indicative of the time when the measurement report was received at the access node does not exceed a predetermined lower time threshold for receiving the measurement report.
  • the adjustment information may comprise channel monitoring information.
  • the channel monitoring information may comprise one or more of:
  • the adjusting the time until expiry of the timer may comprise reducing the time until expiry of the timer, if the channel quality information indicates a channel quality below a
  • the channel occupancy information indicates a channel occupancy above a predetermined upper occupancy threshold.
  • the adjusting the time until expiry of the timer may comprise extending the time until expiry of the timer, if the channel quality information indicates a channel quality above a predetermined upper quality threshold and the channel occupancy information indicates a channel occupancy below a predetermined lower occupancy threshold.
  • the adjusting the time until expiry of the timer may comprise stopping the timer, if the channel quality information indicates a channel quality above a predetermined upper quality threshold and the channel occupancy information indicates a channel occupancy below a predetermined lower occupancy threshold.
  • the method may further comprise evaluating the timer only if the event relates to a predetermined set of measurements configured at the communication device.
  • a measurement in the set of measurements may be identified through a predetermined measurement identity.
  • a measurement in the set of measurements may be identified by an information element in the measurement reporting configuration of the measurement.
  • the method may further comprise including time information in the measurement report indicative of the time when the timer will expire.
  • a method comprising causing transmission of measurement configuration information specifying a measurement event for initiating a handover procedure of a communication device for handover of the communication device to a target cell selected by the communication device; wherein the handover procedure comprises starting, triggered by t e measurement event, a timer; and wherein the measurement configuration information further comprises one or more adjustment parameters for adjusting the time until expiry of the started timer based on adjustment information obtained at the communication device, wherein the adjustment information is indicative of a probability for receiving at the communication device a handover command for network-controlled handover of the communication device before a radio link failure at the communication device occurs.
  • the method may further comprise causing transmission of progress information for a network-controlled handover procedure related to the handover command.
  • the progress information may comprise information acknowledging reception, at an access node of a network, of a measurement report triggered by the measurement event.
  • the progress information may comprise time information indicative of the time when the measurement report was received at the access node.
  • the one or more adjustment parameters may at least be one in:
  • the one or more adjustment parameters may comprise one or more parameters for reducing the time until expiry of the timer if the progress information indicates too slow progress of the network-controlled handover procedure.
  • the progress information may indicate too slow progress of the network-controlled handover procedure, if the information acknowledging reception of the measurement report is received at the communication device at a time which exceeds the upper time threshold for receiving the information acknowledging reception of the measurement report.
  • the progress information may indicate too slow progress of the network-controlled handover procedure, if the time when the measurement report was received at the access node exceeds the upper time threshold for receiving the measurement report at the access node.
  • the one or more adjustment parameters may comprise one or more parameters for extending the time until expiry of the timer if the progress information indicates sufficient progress of the network-controlled handover procedure.
  • the progress information may indicate sufficient progress of the network-controlled handover procedure, if the information acknowledging reception of the measurement report is received at the communication device at a time which does not exceed the lower time threshold for receiving the information acknowledging reception of the measurement report.
  • the progress information may indicate sufficient progress of the network-controlled handover procedure, if the time when the measurement report was received at the access node does not exceed the lower time threshold for receiving the measurement report at the access node.
  • the one or more adjustment parameters may comprise one or more parameters for reducing the time until expiry of the timer if the channel quality measured at the communication device does not exceed a lower quality threshold or the channel occupancy measure for the channel used by the communication device exceeds an upper occupancy threshold.
  • the one or more adjustment parameters may comprise one or more parameters for extending the time until expiry of the timer if the channel quality measured at the
  • the communication device exceeds an upper quality threshold and the channel occupancy measure for the channel used by the communication device does not exceed a lower occupancy threshold.
  • the method may further comprise suspending a network-controlled handover procedure for the communication device, if a measurement report triggered by the measurement event comprises information indicative of the time when the timer will expire and the time left for performing a network-controlled handover does not exceed a time threshold.
  • an apparatus comprising at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus at least to detect at a communication device a measurement event in a network; initiate, triggered by the measurement event, transmission of a measurement report to the network for network-controlled handover of the communication device; start, triggered by the measurement event, a timer; wait for a handover command from the network instructing the communication device to perform handover to a network-selected target cell; initiate transmission of a handover request message to a device-selected target cell, if the timer expires before the handover command is received at the communication device transmission; and adjust the time until expiry of the started timer based on adjustment information obtained at the communication device, wherein the adjustment information is indicative of a probability for receiving the handover command before a radio link failure at the communication device occurs.
  • an apparatus comprising at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code configured, with the at least one processor, to cause the apparatus at least to cause transmission of measurement configuration information specifying a measurement event for initiating a handover procedure of a communication device for handover of the communication device to a target cell selected by the communication device; wherein the handover procedure comprises starting, triggered by the measurement event, a timer; and wherein the measurement configuration information further comprises one or more adjustment parameters for adjusting the time until expiry of the started timer based on adjustment information obtained at the communication device, wherein the adjustment information is indicative of a probability for receiving at the communication device a handover command for network-controlled handover of the communication device before a radio link failure at the communication device occurs.
  • an apparatus comprising means for performing a method according to embodiments of the first aspect.
  • an apparatus comprising means for performing a method according to embodiments of the second aspect.
  • a computer program embodied on a non-transitory computer-readable storage medium, the computer program comprising program code for controlling a process to execute a process, the process comprising detecting at a communication device a measurement event in a network; initiating, triggered by the measurement event, transmission of a measurement report to the network for network- controlled handover of the communication device; starting, triggered by the measurement event, a timer; waiting for a handover command from the network instructing the
  • a computer program embodied on a non-transitory computer-readable storage medium, the computer program comprising program code for controlling a process to execute a process, the process comprising causing transmission of measurement configuration information specifying a measurement event for initiating a handover procedure of a communication device for handover of the communication device to a target cell selected by the communication device; wherein the handover procedure comprises starting, triggered by the measurement event, a timer; and wherein the measurement configuration information further comprises one or more adjustment parameters for adjusting the time until expiry of the started timer based on adjustment information obtained at the communication device, wherein the adjustment information is indicative of a probability for receiving at the communication device a handover command for network-controlled handover of the communication device before a radio link failure at the communication device occurs.
  • a computer program product for a computer comprising software code portions for performing the steps of a method according to embodiments of the first aspect.
  • a computer program product for a computer comprising software code portions for performing the steps of a method according to embodiments of the second aspect.
  • a mobile communication system comprising at least one apparatus according to the third aspect and at least one apparatus according to the forth aspect.
  • a mobile communication system comprising at least one apparatus according to the fifth aspect and at least one apparatus according to the sixth aspect.
  • Figure 1 shows a schematic diagram of an example communication system comprising a base station and a plurality of communication devices
  • Figure 2 shows a schematic diagram of an example mobile communication device
  • Figure 3 shows an example for a communication device operating in a license-exempt radio spectrum
  • Figure 4 shows an example of an autonomous mobility procedure of a communication device in an LTE-based system operated on license-exempt radio spectrum
  • Figure 5 shows a schematic diagram illustrating a method of a communication device
  • Figure 6 shows a signaling diagram illustrating an embodiment of the present invention
  • Figure 7 shows an example flow chart related to the measurement reporting according to the present invention
  • Figure 8 shows an example flow chart of the procedure for adjusting the time until expiry of the AUM timer
  • Figure 9 illustrates an example of measurement configuration
  • Figure 10 shows a schematic diagram of an example control apparatus
  • control apparatus 108 and 109 are shown to control the respective macro level base stations 106 and 107.
  • the control apparatus of a base station can be interconnected with other control entities.
  • the control apparatus is typically provided with memory capacity and at least one data processor.
  • the control apparatus and functions may be distributed between a plurality of control units.
  • the control apparatus may additionally or alternatively be provided in a radio network controller.
  • LTE systems may however be considered to have a so-called "flat" architecture, without the provision of RNCs; rather the (e)NB is in communication with a system architecture evolution gateway (SAE-GW) and a mobility management entity (MME), which entities may also be pooled meaning that a plurality of these nodes may serve a plurality (set) of (e)NBs.
  • SAE-GW is a "high-level" user plane core network element in LTE, which may consist of the S-GW and the P-GW (serving gateway and packet data network gateway, respectively). The functionalities of the S-GW and P-GW are separated and they are not required to be co-located.
  • base stations 106 and 107 are shown as connected to a wider communications network 1 13 via gateway 1 12.
  • a further gateway function may be provided to connect to another network.
  • the smaller base stations 1 16, 1 18 and 120 may also be connected to the network 1 13, for example by a separate gateway function and/or via the controllers of the macro level stations.
  • the base stations 116, 1 18 and 120 may be pico or femto level base stations or the like.
  • stations 1 16 and 1 18 are connected via a gateway 1 1 1 whilst station 120 connects via the controller apparatus 108.
  • the smaller stations may not be provided.
  • Smaller base stations 1 16, 1 18 and 120 may be part of a second network, for example WLAN and may be WLAN APs.
  • a possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200.
  • a communication device is often referred to as user equipment (UE) or terminal.
  • An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals.
  • Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a 'smart phone', a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, or any combinations of these or the like.
  • MS mobile station
  • PDA personal data assistant
  • a mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.
  • the mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals.
  • transceiver apparatus is designated schematically by block 206.
  • the transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement.
  • the antenna arrangement may be arranged internally or externally to the mobile device.
  • a mobile device is typically provided with at least one data processing entity 201 , at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices.
  • the data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204.
  • the user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like.
  • a display 208, a speaker and a microphone can be also provided.
  • a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.
  • the communication devices 102, 104, 105 may access the communication system based on various access techniques, such as code division multiple access (CDMA), or wideband CDMA (WCDMA).
  • CDMA code division multiple access
  • WCDMA wideband CDMA
  • Other non-limiting examples comprise time division multiple access (TDMA), frequency division multiple access (FDMA) and various schemes thereof such as the interleaved frequency division multiple access (I FDMA), single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA), space division multiple access (SDMA) and so on.
  • Signaling mechanisms and procedures which may enable a device to address in-device coexistence (IDC) issues caused by multiple transceivers, may be provided with help from the LTE network.
  • the multiple transceivers may be configured for providing radio access to different radio technologies.
  • 3GPP 3rd Generation Partnership Project
  • LTE long-term evolution
  • UMTS Universal Mobile Telecommunications System
  • LTE-A LTE Advanced
  • the LTE employs a mobile architecture known as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN).
  • Base stations of such systems are known as evolved or enhanced Node Bs (eNBs) and provide E-UTRAN features such as user plane Packet Data Convergence/Radio Link Control/Medium Access Control/Physical layer protocol (PDCP/RLC/MAC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices.
  • eNBs evolved or enhanced Node Bs
  • eNBs evolved or enhanced Node Bs
  • eNBs evolved or enhanced Node Bs
  • RRC Radio Resource Control
  • Other examples of radio access system comprise those provided by base stations of systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide
  • a base station can provide coverage for an entire cell or similar radio service area.
  • license-exempt radio bands (whether LTE-based radio access technology or otherwise) will cause uncertainty with regards to the channel access to transmit on the radio channel, and this uncertainty is present for both downlink transmissions from the serving eNB 20S (which the communication device needs for monitoring the radio link and for receiving data) and for the uplink transmissions from the communication device (which the communication device needs to transmit its measurement reports and data).
  • the serving eNB 20S which the communication device needs for monitoring the radio link and for receiving data
  • the uplink transmissions from the communication device which the communication device needs to transmit its measurement reports and data.
  • a communication device starts experiencing a poor channel this can be caused by either lack of coverage or by a lack of sufficient signals for measurements. The latter can occur when the radio channel is busy/highly occupied, and this will typically also mean the
  • Figure 4 shows an example signaling scheme for handover of a communication device in a LTE-based radio access system, such as MulteFire, operated on license-exempt radio spectrum, or LTE stand alone on unlicensed radio spectrum.
  • the scheme comprises a NW- controlled handover procedure known from conventional LTE complemented by a procedure for AUM handover of a communication device.
  • NW-controlled handover procedure known from conventional LTE complemented by a procedure for AUM handover of a communication device.
  • This is an example of a partially network controlled handover, where UE is configured by the network to be able to do autonomous handover under certain conditions (e.g. when the AUM timer expires, the communication device would trigger handover to a target eNB, without necessarily being able to
  • the communication device is configured to perform measurements on signals transmitted in the serving cell and potential target cells.
  • the communication device triggers an event, such as the A3 event in LTE (used as non-limiting example here, but any other event leading to a handover or cell change may be used), when the source cell meets a specified entry condition for at least a certain time interval (for example configured by the parameter 'timeToTrigger' in LTE).
  • the entry condition is met, when a measured signal quality, such as the reference signal received power (RSRP) in a neighboring cell (potential target cell) becomes better than an offset relative to a respective signal quality measured in the serving cell.
  • RSRP reference signal received power
  • the communication device initiates the transmission of a measurement report to the network for informing the network about the occurrence of the event.
  • the network may decide for NW-controlled handover whether the communication device should be handed over from the serving (source) cell to a target cell.
  • the access node of the source cell sends a Handover Request message to a potential target cell to prepare for handover of the communication device.
  • the Handover Request message contains information (e.g., UE context information, Radio Access Bearer context information) needed at the target cell for performing the handover.
  • the access node controlling the target cell performs call admission control, and responds with a Handover Request Acknowledgement message, if it can provide resources for accommodating the communication device. After transmission of the Handover Request Acknowledgement message the target cell is prepared for handover of the communication device.
  • the Handover Request Acknowledgement message includes reconfiguration information, such as the RRC Connection Reconfiguration message in LTE comprising a MobilityControllnfo information element.
  • the reconfiguration information is destined for the communication device and needs to be forwarded by the access node of the source cell.
  • NW-controlled handover the access node of the source cell transmits the reconfiguration information in a handover command to the communication device.
  • the reconfiguration information comprises information needed at the communication for connecting to the target cell (corresponding to information provided in full or at least partial RRC configuration for AUM handover), and usual NW-controlled handover of the
  • the communication device may be configured by the network to initiate the handover to a target cell autonomously based on configuration information provided by the network in advance. Therefore, the AUM timer may be started when the measurement report in Figure 4 is triggered. The AUM timer may be set such that expiry of the timer indicates that the NW-controlled handover procedure is not going to succeed, or at least not going to succeed in time. Failure of the NW-controlled handover procedure may be caused by, for example, high channel occupancy (busy channel) in license-exempt spectrum.
  • Failing CCA procedures due to high channel occupancy may at least delay the transmission of the measurement report in uplink and/or the transmission of the handover command in downlink. Such delays may increase the risk of a radio link failure to occur at the communication device. Therefore, the communication device may initiate a AUM handover procedure as a fallback procedure, once it has detected that the NW-controlled handover has failed or will at least not succeed in time.
  • the communication device may transmit an AUM handover request message to a selected target cell (for example, similar to the message in the re- establishment procedure in LTE).
  • This message may be included in a random access procedure towards the target cell.
  • the random access procedure may use contention-based or contention-free random access, depending on pre-configuration information related to target cell available at the communication device and the target cell selected by the communication device.
  • the target cell may acknowledge the AUM handover request in a message to the communication device.
  • the access node in the target cell may further inform the access node of the source about the AUM handover request, and may fetch from the source cell, if needed, any missing information for accommodating the communication device depending on the extent of pre-configuration of the communication device at the target cell.
  • Such techniques may in particular comprise adjusting the time until expiry of the AUM timer based on adjustment information indicative of a probability for receiving a handover command at the communication device before a radio link failure at the communication device occurs.
  • FIG. 5 shows an example method of a communication device for AUM handover in a mobile network.
  • the communication device detects a measurement event, for example the A3 event in LTE, in a serving cell of the network. This event may indicate an upcoming necessity to handover the communication device to another cell. The method proceeds to step 520.
  • a measurement event for example the A3 event in LTE
  • the communication device initiates, triggered by the measurement event, transmission of a measurement report to an access node of the network.
  • the transmission of the measurement report may be subject to the outcome of a clear channel assessment (CCA) procedure, and may be delayed until the CCA procedure succeeds.
  • CCA clear channel assessment
  • the measurement report may comprise information, which the network may use for deciding whether the communication device should be handed over from the serving cell (source cell) to a target cell. If the measurement report is received successfully at an access node of the network, the network may initiate a NW-controlled handover procedure based on the measurement report. Specifically, the network may decide whether the communication device should be handed over from the source cell to a target cell selected by the network. In case of a successful NW-controlled handover the source cell provides respective reconfiguration information in a handover command to the communication device. The method proceeds to step 530. At step 530, the communication device starts, triggered by the measurement event, the AUM timer. The time interval until expiry of the AUM timer may be preconfigured by the network or may be predefined by the standard.
  • Respective configuration information may include elements for scaling of the time interval, for example, depending on the speed of communication device or depending on the availability of prepared potential target cells.
  • the effective length of the timer interval may be shorter, if the communication device is moving fast or if there is at least one suitable target cell prepared for handover of the communication device.
  • the configuration information may include a minimum time interval until expiry of the timer to allow at least for transmission of already scheduled data in the source cell before AUM handover is initiated. The method proceeds to step 540.
  • the communication device waits for the transmission of the handover command from the access node of the source cell.
  • the communication device adjusts the time until expiry of the started AUM timer based on adjustment information obtained at the communication device, wherein the adjustment information is indicative of a probability for receiving the handover command before a radio link failure at the communication device occurs. If the AUM timer expires before the communication device has received the handover command, the method proceeds to step 560 for performing AUM handover. At step 560 the communication device initiates transmission of a handover request message to a target cell selected by the communication device.
  • the adjustment information in step 550 may comprise progress information from the network indicative of a progress of the network-controlled handover.
  • this progress information may comprise information acknowledging reception of the measurement report at an access node of the network.
  • This access node may be the access node controlling the serving cell (source cell).
  • the information acknowledging reception of the measurement report may be transmitted in a measurement acknowledgement message from the network to the communication device.
  • the progress information may comprise time information indicative of the time when the measurement report was received at the access node. This time information may be transmitted in the measurement acknowledgement message.
  • the progress information may indicate too slow progress of the network- controlled handover, if the information acknowledging reception of the measurement report was received after a predetermined upper time threshold for acknowledging the
  • the upper time threshold for acknowledging the measurement report by the network may be configured by the network.
  • progress information indicating too slow progress of the network- controlled handover may immediately cause initiation of the AUM handover procedure in step 560, i.e. the time interval until expiry of the AUM timer is set to zero, since the NW- controlled handover proceeds too slow for safe handover of the communication device to a target cell under control of the network.
  • the progress information may indicate too slow progress of the network- controlled handover, if the information indicative of the time when the measurement report was received at the access node exceeds a predetermined upper time threshold for receiving the measurement report at the access node.
  • Adjusting the time until expiry in step 550 may comprise extending the time until expiry of the AUM timer, if the progress information indicates sufficient progress of the network-controlled handover for ensuring a reliable or safe handover of the communication device to a network- controlled target cell.
  • the time until expiry of the timer may be extended, if for example the communication device does not know a prepared target. In such a case, a short time interval until expiry of the AUM timer may initially be selected, which would still allow for initiating AUM handover, if the NW-controlled handover procedure proceeds too slow. But once the communication device is informed about the NW-controlled handover proceeding sufficiently fast, the communication device may rely on the NW-controlled handover to succeed in time, and may extend the time until initiation of the AUM handover.
  • the progress information may indicate sufficient progress of the network controlled handover, if the information acknowledging reception of the measurement report was received before a predetermined lower time threshold for acknowledging the measurement report by t e network.
  • the lower time threshold for acknowledging the measurement report by the network may be configured by the network.
  • the progress information may indicate sufficient progress of the network controlled handover, if the information indicative of the time when the measurement report was received at the access node does not exceed a predetermined lower time threshold for receiving the measurement report at the access node.
  • the lower time threshold for receiving the measurement report at the access node may be configured by the network.
  • a new AUM measurement report ACK may be defined, which the network would configure the communication device with.
  • the ACK could be defined for example as a new RRC message (currently measurement reports are not acknowledged), or alternatively the communication device could derive the ACK from RLC status reports by tracking which PDU(s) contain the measurement report corresponding to measurement identifier (ID) associated with AUM event.
  • a measurement report acknowledgment message may be transmitted from the network for acknowledging reception of the measurement report to the communication device.
  • the measurement report ACK may be transmitted in as a new RRC message, or the communication device may alternatively derive measurement report ACK information from radio link control (RLC) status reports by tracking which protocol data units (PDU(s)) contain the measurement report potentially triggering a AUM handover (for example by tracking which PDU(s) contain the measurement report corresponding to measurement ID associated with AUM event).
  • RLC radio link control
  • the search for measurement report ACKs in response to the transmission of certain measurement reports may be configured at the communication device.
  • Respective configuration information may be part of the measurement reporting configuration provided by the network. This configuration information may be explicit information included in RRC signalling, for example in the reportConfigEUTRA information element. Alternatively, this configuration information may be more implicitly indicated, for example by including optional information related to the AUM timer in reportConfigEUTRA information element.
  • the adjustment information in step 550 may comprise channel monitoring information.
  • This information may be used at the communication device to determine whether the known signal quality information is still reliable, i.e. whether there are sufficient measurement opportunities for measuring the signal quality at the communication device. This information may further be used to determine whether the measured signal quality is still sufficient to ensure a safe handover of the communication device.
  • the channel monitoring information may further comprise information indicative of potential delays in the NW-controlled handover procedure due to a high number of access requests from other network elements and devices to the downlink and/or the uplink channel in the source cell. Accordingly, the channel monitoring information may comprise, for example, channel quality information determined at the communication device, and/or channel occupancy information.
  • Adjusting the time until expiry in step 550 may comprise reducing the time until expiry of the AUM timer, if the channel quality information indicates a channel quality below a
  • predetermined lower quality threshold and/or the channel occupancy information indicates a channel occupancy exceeding a predetermined upper occupancy threshold.
  • the lower quality threshold and/or the upper occupancy threshold may be configured by the network.
  • channel monitoring information may cause immediate initiation of the AUM handover procedure in step 560, i.e. the time interval until expiry of the AUM timer is set to zero, if the measured signal quality is too low or cannot be determined reliably, or if the uplink and/or downlink channel is so occupied that the NW-controlled handover procedure is likely to proceed too slow for safe handover to a target cell under control of the network.
  • Adjusting the time until expiry in step 550 may comprise extending the time until expiry of the AUM timer, if the channel quality information indicates a channel quality above a
  • predetermined upper quality threshold and the channel occupancy information indicates a channel occupancy below a predetermined lower occupancy threshold.
  • the upper quality threshold and/or the lower occupancy threshold may be configured by the network.
  • adjusting the time until expiry in step 550 may comprise stopping the timer (corresponds to setting the time interval until expiry of the AUM timer to an infinite value), if the channel quality information indicates a channel quality above a predetermined upper quality threshold and the channel occupancy information indicates a channel occupancy below a predetermined lower occupancy threshold.
  • the entry condition related to the stay/cancel event may be monitored while the AUM timer is running. If the stay/cancel event is triggered, the AUM timer may at least extend the time until expiry of the AUM timer, for example by restarting the AUM timer.
  • the AUM timer may be stopped or the time until expiry may be set to an infinite value, i.e. the AUM handover is canceled.
  • Actions related to the stay/cancel event may be performed for ensuring, that AUM handover is not initiated by the communication device, if channel monitoring information, for example the signal quality, improves beyond a certain threshold which allows at least for postponing initiation of the AUM handover. This may give a NW-controlled handover more time to succeed.
  • the communication device may inform the network about the postponing or cancelling of the AUM handover.
  • the communication device may even ignore the handover command from a successful NW-controlled handover, for example if the communication device has cancelled the AUM handover after a respective stay/cancel event has been triggered.
  • the communication device may inform the network that it will ignore a handover command already received or still to receive from the network.
  • Cancelling of a AUM handover and /or ignoring of a handover command from NW-controlled handover may avoid useless handover of the communication device back and forth between the source cell and a target cell.
  • the stay/cancel event may cause the communication device to send another measurement report, for the stay event. In this case, if this is sent early enough and the signal quality has improved sufficiently, the network could even refrain from commanding a handover - or at least postpone it. Note, that in general, the handover may not be cancelled even if the AUM is cancelled. This is because the network may not know that communication device has triggered a stay/cancel event for AUM, unless a respective indication or report arrives in time. For example, similar triggering criteria as for existing measurement events (e.g. Event A3) may be reused, but in relation to the AUM timer.
  • Similar triggering criteria as for existing measurement events e.g. Event A3 may be reused, but in relation to the AUM timer.
  • the event monitoring would be started when the communication device starts AUM timer, and stay/cancel event triggering before AUM is initiated would stop the AUM timer until a new event possibly starts it again.
  • information related to a stay/cancel event may cause the network to postpone the transmission of the handover command or even to refrain from the transmission of the handover command to the communication device, if this information is received early enough by the network.
  • the network may postpone the transmission of the handover command or may even refrain from its transmission, for example, if the measured signal quality has improved beyond a certain threshold after the AUM timer has been started.
  • Respective monitoring information may be provided in the measurement report when the stay/cancel event has been triggered.
  • the stay/cancel event may be implemented similar to existing
  • Monitoring of the entry condition for the stay/cancel event may be started when the communication device starts the AUM timer, and triggering of the stay/cancel event before the AUM timer has expired may at least extend the time until expiry of the AUM timer or may even stop the AUM timer. This may happen, if the communication device, for example, stops moving (or at least stops moving fast), changes its direction, or if the interference conditions have changed (in case a RSRQ-like based event is used - for example, similar to LTE, but not restricted to it). In such cases, it may not be necessary for the communication device to initiate AUM handover, when the signal quality of the serving cell has recovered sufficiently for performing NW- controlled handover.
  • the communication device may perform the following steps:
  • the handover event may be triggered, the communication device may initiate the transmission of the measurement report for handover, and the AUM timer may be started.
  • the communication device may monitor the trigger condition (for example, signal quality being above a threshold for a certain time (e.g. X ms), or LBT success rate being sufficiently high (determined, for example, based on the communication device's success rate to perform measurements and/or to obtain the channel for sending measurement reports) of the stay/cancel event.
  • the trigger condition for example, signal quality being above a threshold for a certain time (e.g. X ms), or LBT success rate being sufficiently high (determined, for example, based on the communication device's success rate to perform measurements and/or to obtain the channel for sending measurement reports) of the stay/cancel event.
  • the communication device may stop the AUM Timer, and the communication device may further send a
  • the communication device may in this scenario not initiate the AUM handover, but may rather wait for control actions from the network, since the signal quality has improved and a radio link failure is unlikely to occur.
  • the entry condition for triggering the stay/cancel event may be based on radio link monitoring (used typically for triggering radio link failures), as follows:
  • radio link evaluation if the evaluation of Qin conditions are fulfilled for time window ms, then that could restart/stop AUM timer, otherwise continue running the AUM timer.
  • the source eNB may, after having received information related to a stay/cancel event from the communication device, reject a handover message related to the communication device from a target eNB.
  • the rejection may be implemented such that the source eNB does not forward the handover message to the communication device.
  • the source eNB may inform the target eNB that the UE will not connect to the target eNB, and the target eNB may be able to reallocate resources reserved in the target cell for handover of the communication device after such a "handover reject" message.
  • the AUM timer is only evaluated if the measurement event in step 510 relates to a predetermined set of measurements configured at the communication device.
  • a measurement in said set of measurements may be identified through a predetermined measurement identity.
  • a respective set of measurement identities may be configured by the network or may be predefined in the standard.
  • a measurement in said set of measurements may be identified by an information element in the measurement reporting configuration of the measurement.
  • the measurement reporting configuration may include information related to the AUM timer, such as a request to include AUM timer information in at least some of the measurement reports.
  • the communication device may in particular include information, such as information indicative of the time until expiry of the AUM timer in the measurement report in step 520.
  • the communication device may alternatively or additionally include information, such as time stamping information, in the measurement report indicative of the time when the measurement report was triggered.
  • the network may configure the communication device with a specific set of measurement identifications (IDs) to be reserved for AUM handover.
  • IDs measurement identifications
  • Respective information may be indicated explicitly, or indicated implicitly by configuring/including AUM timer information in the measurement reporting configuration linked to a measurement ID or a set of measurement IDs.
  • the communication device may expect to receive a measurement report acknowledgment message (measurement report ACK) from the network. This may cause one or more of the following actions:
  • the communication device may set a radio link control (RLC) poll request bit. This may cause the network to send the RLC status immediately, once it has
  • the communication device may include time stamp information in the measurement report to inform the network when the measurement report was triggered.
  • the network may infer from the time stamp information when the AUM timer will expire, and may use this information to decide on, whether it should still attempt to perform NW-controlled handover of the communication device. In case, the network decides that there is not sufficient time left for performing successful NW-controlled handover, it may decide to continue serving the communication device in the source cell, until the communication device initiates AUM handover after expiry of the AUM timer.
  • the communication device may suspend a configured discontinuous reception
  • the communication device and the network may be configured to perform one or more of these actions only when a measurement report intended for AUM operation was triggered in the communication device and transmitted to the network.
  • the benefit of such selective execution of AUM-related action is that the signaling effort in the network as well as the power consumption in the communication device is reduced.
  • the communication device signals information regarding adjustments of the AUM timer to the network.
  • the network may be able to infer from this information the time when the AUM timer will expire at the communication device.
  • the network may stop activities related to the network-controlled handover procedure of the communication device if the time left until expiry of the AUM timer is too short for completing the NW-controlled handover successfully.
  • the communication device may receive information related to the configuration of the AUM timer after the AUM timer has been started. The communication device may consider this updated configuration information, and may adjust the time until expiry of the AUM timer accordingly.
  • Figure 6 shows an example signaling flow based on the method of Figure 5.
  • the source eNB (access node of the serving/source cell) configures the communication device to perform measurement reporting for an AUM handover procedure.
  • the configuration may include a measurement event triggering a measurement report and control information related to an AUM timer.
  • the measurement configuration may include parameters related to actions in response to a message from the network acknowledging reception of a measurement report (measurement report ACK) transmitted by the communication device.
  • the measurement report ACK may be based on an explicit RRC message from the network. Alternatively, the measurement report ACK may be based on the communication device tracking status reports on radio link control (RLC) layer.
  • the communication device may use information from the measurement report ACK for stopping, (re)setting or adjusting the AUM timer.
  • the communication device triggers the configured event, starts the AUM timer and initiates transmission of the measurement report based on the received measurement reporting configuration.
  • the transmission of the measurement report in step 625 may be delayed by a time 620 when the uplink channel is occupied, until the LBT procedure performed by the communication device succeeds.
  • the source eNB may record in step 630 a reference time T_0 as, for example, the time when the measurement report has been received/detected or time when the source eNB transmits a Handover Request message to a potential target cell, or the creation time of the message.
  • the source eNB may further initiate the transmission of a measurement report ACK message in step 630.
  • the transmission of this measurement report ACK message in step 640 may be delayed by a time 635 when the downlink channel is occupied, until the LBT procedure performed by the source eNB succeeds.
  • the measurement report ACK message may include the reference time T_0 when the measurement report has been
  • the target eNB (access node in the target cell) may perform call admission control in step 650 and may prepare the handover of the communication device to the target cell.
  • the target eNB may send a Handover Request Acknowledgement message to the source eNB in step 660. This message may comprise information for a handover command to the communication device.
  • the target cell After transmission of the Handover Request Acknowledgement message the target cell is prepared for handover of the communication device, and the time between the Handover Request message in step 630 and the Handover Request
  • Acknowledgement message in step 660 may be referred to as handover preparation time T_prep.
  • the communication device may record the time T_current when it receives/detects the measurement report ACK message transmitted in step 640.
  • the measurement report ACK message may be very short. If the measurement report ACK is conveyed through a RLC status report, it may essentially only contain one bit for indicating acknowledgement of the measurement report. Thus, the measurement report ACK may not convey information specifying the action of the communication device requested by the network regarding the AUM handover. In an embodiment, respective information, for example information for adjusting the time until expiry of the AUM timer, may therefore be preconfiguring at the communication device.
  • the measurement report ACK is transmitted in a message using RRC signaling, this message may be used to explicitly indicate the action requested by the network.
  • the UE configuration of UE action includes a time information.
  • the time is given in reference to the time of triggering of the AUM event and measurement report (i.e. when Timer A is started).
  • An example is that if Timer A is set to 100 ms, and the measurement report ACK arrives after 50 ms is elapsed, the UE will restart Timer A to allow time for NW controlled HO. Otherwise (ACK arrives before 50 ms), the UE will keep the AUM Timer (here denoted as Timer A) running as it is.
  • the eNB will time stamp the measurement report ACK (e.g. with SFN).
  • timer A 100 ms
  • time from measurement report ACK time stamp i.e. creation
  • AUM 50 ms.
  • AUM timer (Timer A here in example) may be defined as:
  • the communication device may be configured such that it reserves a predetermined maximum time T_prep for preparing the NW-controlled handover.
  • the communication device may further be configured to subtract from the maximum allowed time T_prep the time (T_current - T_0) already elapsed for preparing the NW-controlled handover, and recalculates the AUM timer in step 655.
  • the measurement report ACK message may comprise time stamp information indicating the creation time (for example T_0) of the message or an
  • the communication device may be informed until when the network requests or expects the communication device to wait until initiation of the AUM handover in step 665.
  • the source eNB and/or the communication device may be able to determine the delay times 620 and 635, respectively.
  • the source eNB may, for example, take the delay time 620 into account when it determines the intended/requested updated expiry time of the AUM timer.
  • the source eNB and/or the communication device may be able to compensate to some extent for effects of the delay times 620 and 635, or may at least be able to consider potential effects of these delays on the handover procedure. For example, if the measurement report ACK message contains the intended/requested updated expiry time, the network may set this time value based on information available in the network on the expected time for handover preparation and the time lapsed for the transmission of the measurement report including the delay time 620. The communication device may immediately initiate AUM handover, if it receives the measurement report ACK message and detects that the AUM timer has already expired when requested or needed adjustments based on this message are applied.
  • the communication devices initiates AUM handover in step 665, when the AUM timer expires and sends a respective random access message to the target cell in step 670.
  • Figure 7 shows an example flow chart related to the measurement reporting step 520. If the measurement report is triggered for a measurement ID linked to an event, which may potentially cause AUM handover, the communication device may expect to receive a measurement report ACK in response to a transmitted measurement report. In this case:
  • the communication device may set a RLC poll request bit when it transmits the measurement report.
  • the communication device may further include a time stamp information in the
  • the communication device may further suspend DRX operation at the
  • RLC poll request bit the measurement report is transmitted may cause the source eNB to send the RLC status report as fast as possible. This minimizes the delay in getting feedback from the network, which is essential as the communication device is likely in need of urgent handover. In such a situation, any additional delay increases the risk of a link failure to occur in the communication device before the communication device can be handed over to a more suitable cell. A delay may further lengthen the time in which user data transmission to/from the communication device is interrupted.
  • Including time stamp information in the measurement report gives the network information, from which it may derive when the AUM timer in the communication device will expire (based on information on the configuration of the AUM timer available in the network).
  • SFN system frame number
  • the network may decide what is the best course of action. If there is enough time left, it may go ahead with performing the NW-controlled handover. Otherwise, if there is less time remaining than the expected time for processing, preparing and signaling of the NW-controlled handover, the network may continue scheduling the communication device by the source eNB until the time, the communication device initiates the AUM handover.
  • Suspending a potential DRX operation at the communication device may ensure that the communication device does not go to DRX sleep mode when the measurement report ACK is to arrive. Suspension of the DRX operation may become effective M ms after the measurement report has been triggered, where the time of M ms indicates the earliest time the measurement report ACK may be received considering the transmission and processing delays at both the communication device and the network.
  • Figure 8 shows an example flow chart of the procedure performed by the communication device. The adjustment of time until expiry of the AUM timer after reception of the measurement report ACK for a measurement report may be performed based on information preconfigured at the communication device.
  • the network may have configured the communication device with the AUM event and an initial time until expiry of the AUM timer. The network may have further configured actions the communication device is expected to perform in response to a measurement report ACK form the network.
  • Potential actions may include: 1. Extend/restart t e AUM timer (here denoted as Timer A)
  • Timer A Shorten the AUM timer (here denoted as Timer A)
  • Timer A the AUM timer (here denoted as Timer A) running If the measurement report ACK is transmitted in a RRC message, this message may include additional information on the action requested by the network. For example, the RRC message may instruct the communication device to reset the AUM timer to a specific time until expiry based on time stamp information in the measurement report ACK. Extending or restarting the AUM timer may be useful when:
  • the communication device is configured with early periodic measurement reports (these are intended to help in target cell preparation/configuration, not result in HO yet), and successfully received measurement report may extend the time before the communication device initiates AUM handover
  • AUM handover could be also cancelled (i.e. the AUM timer is stopped)
  • Shortening AUM timer may be useful when:
  • the communication device is configured with single event based reporting, and the measurement report arrives late and immediate handover is needed
  • Figure 9 illustrates an example of measurement configuration.
  • the configuration includes the AUM timer (here called Timer A) (started when the event is triggered; UE initiates autonomous mobility to target cell if Timer A expires), so for measurement reports sent for that ID, the UE expects an ACK and performs the corresponding actions (1 -3 in the list above).
  • the configuration does not include the optional AUM timer (here denoted as Timer A), so the communication device (UE) does not expect an ACK and thus does not perform the actions related to that.
  • FIG. 10 shows an example of a control apparatus for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, (e) node B or 5G AP, a central unit of a cloud architecture or a node of a core network such as an MME or S-GW, a scheduling entity, or a server or host.
  • a station of an access system such as a RAN node, e.g. a base station, (e) node B or 5G AP, a central unit of a cloud architecture or a node of a core network such as an MME or S-GW, a scheduling entity, or a server or host.
  • the method may be implanted in a single control apparatus or across more than one control apparatus.
  • the control apparatus may be integrated with or external to a node or module of a core network or RAN.
  • base stations comprise a separate control apparatus unit or module.
  • the control apparatus can be another network element such as a radio network controller or a spectrum controller.
  • each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller.
  • the control apparatus 300 can be arranged to provide control on communications in the service area of the system.
  • the control apparatus 300 comprises at least one memory 301 , at least one data processing unit 302, 303 and an input/output interface 304.
  • control apparatus Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station.
  • the receiver and/or the transmitter may be implemented as a radio front end or a remote radio head.
  • control apparatus 300 can be configured to execute an appropriate software code to provide the control functions.
  • Control functions may comprise providing configuration information for AUM measurements.
  • apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception.
  • apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.
  • the embodiments of this invention may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware.
  • Computer software or program also called program product, including software routines, applets and/or macros, may be stored in any apparatus-readable data storage medium and they comprise program instructions to perform particular tasks.
  • a computer program product may comprise one or more computer- executable components which, when the program is run, are configured to carry out embodiments.
  • the one or more computer-executable components may be at least one software code or portions of it.
  • any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions.
  • the software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.
  • the physical media is a non-transitory media.
  • the memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.
  • the data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.
  • Embodiments of the inventions may be practiced in various components such as integrated circuit modules.
  • the design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)

Abstract

La présente invention concerne un procédé qui comprend : la détection, au niveau d'un dispositif de communication, d'un événement de mesure dans un réseau; le lancement, déclenché par l'événement de mesure, de la transmission d'un rapport de mesure au réseau permettant un transfert intercellulaire commandé par réseau du dispositif de communication; le démarrage, déclenché par l'événement de mesure, d'un temporisateur; l'attente d'une instruction de transfert intercellulaire provenant du réseau et ordonnant au dispositif de communication d'effectuer un transfert intercellulaire vers une cellule cible sélectionnée par le réseau; le lancement de la transmission d'un message de demande de transfert intercellulaire à une cellule cible sélectionnée par un dispositif; si le temporisateur expire avant que l'instruction de transfert intercellulaire ne soit reçue au niveau de la transmission de dispositif de communication, le réglage du temps jusqu'à l'expiration du temporisateur démarré sur la base d'informations de réglage obtenues au niveau du dispositif de communication, les informations de réglage indiquant une probabilité de réception de l'instruction de transfert avant qu'une rupture de liaison radio au niveau du dispositif de communication ne se produise.
PCT/EP2018/056180 2017-04-24 2018-03-13 Temporisateur permettant une mobilité autonome d'un dispositif de communication dans des réseaux cellulaires WO2018197097A1 (fr)

Applications Claiming Priority (6)

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EP2017059682 2017-04-24
EPPCT/EP2017/059682 2017-04-24
EP2017059943 2017-04-26
EPPCT/EP2017/059943 2017-04-26
EPPCT/EP2017/060072 2017-04-27
EP2017060072 2017-04-27

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WO2019215666A1 (fr) * 2018-05-10 2019-11-14 Nokia Technologies Oy Appareil et procédé d'optimisation de confirmation de transfert conditionnel
EP3681243A1 (fr) * 2019-01-10 2020-07-15 Nokia Technologies Oy Amélioration de l'efficacité de communication
CN112543463A (zh) * 2019-09-23 2021-03-23 上海朗帛通信技术有限公司 一种被用于无线通信的节点中的方法和装置
WO2021160585A1 (fr) * 2020-02-14 2021-08-19 Nokia Technologies Oy Compte rendu de mesure amélioré pour procédure de transfert conditionnel
CN115088305A (zh) * 2020-02-13 2022-09-20 诺基亚技术有限公司 兼容辅节点有条件小区改变的改进主节点的有条件切换
US11582660B2 (en) 2020-05-22 2023-02-14 Samsung Electronics Co., Ltd. Method and base station for handover management in wireless network
EP4280689A4 (fr) * 2021-01-14 2024-01-24 Beijing Xiaomi Mobile Software Co Ltd Procédé et appareil de transfert de cellule, dispositif de communication et support de stockage

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2019215666A1 (fr) * 2018-05-10 2019-11-14 Nokia Technologies Oy Appareil et procédé d'optimisation de confirmation de transfert conditionnel
US11419023B2 (en) 2018-05-10 2022-08-16 Nokia Technologies Oy Apparatus and method for optimization of conditional handover confirmation
EP3681243A1 (fr) * 2019-01-10 2020-07-15 Nokia Technologies Oy Amélioration de l'efficacité de communication
CN112543463A (zh) * 2019-09-23 2021-03-23 上海朗帛通信技术有限公司 一种被用于无线通信的节点中的方法和装置
CN112543463B (zh) * 2019-09-23 2022-07-01 上海朗帛通信技术有限公司 一种被用于无线通信的节点中的方法和装置
CN115088305A (zh) * 2020-02-13 2022-09-20 诺基亚技术有限公司 兼容辅节点有条件小区改变的改进主节点的有条件切换
WO2021160585A1 (fr) * 2020-02-14 2021-08-19 Nokia Technologies Oy Compte rendu de mesure amélioré pour procédure de transfert conditionnel
US11582660B2 (en) 2020-05-22 2023-02-14 Samsung Electronics Co., Ltd. Method and base station for handover management in wireless network
EP4280689A4 (fr) * 2021-01-14 2024-01-24 Beijing Xiaomi Mobile Software Co Ltd Procédé et appareil de transfert de cellule, dispositif de communication et support de stockage

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