EP4256841A1 - Gestion de mobilité améliorée pour équipement utilisateur nb-ido avant une défaillance de liaison radio - Google Patents

Gestion de mobilité améliorée pour équipement utilisateur nb-ido avant une défaillance de liaison radio

Info

Publication number
EP4256841A1
EP4256841A1 EP21823837.6A EP21823837A EP4256841A1 EP 4256841 A1 EP4256841 A1 EP 4256841A1 EP 21823837 A EP21823837 A EP 21823837A EP 4256841 A1 EP4256841 A1 EP 4256841A1
Authority
EP
European Patent Office
Prior art keywords
user equipment
measurements
investigation
threshold
cell
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21823837.6A
Other languages
German (de)
English (en)
Inventor
Volker Breuer
Lars Wehmeier
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Telit Cinterion Deutschland GmbH
Original Assignee
Telit Cinterion Deutschland GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Telit Cinterion Deutschland GmbH filed Critical Telit Cinterion Deutschland GmbH
Publication of EP4256841A1 publication Critical patent/EP4256841A1/fr
Pending legal-status Critical Current

Links

Classifications

    • 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
    • H04W36/30—Reselection being triggered by specific parameters by measured or perceived connection quality data
    • H04W36/305—Handover due to radio link failure
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W24/00—Supervisory, monitoring or testing arrangements
    • H04W24/10—Scheduling measurement reports ; Arrangements for measurement reports
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
    • H04W88/02—Terminal devices
    • H04W88/021—Terminal devices adapted for Wireless Local Loop operation

Definitions

  • the present invention relates to a method to manage mobility prior Radio Link Failure in a NarrowBand-lnternet of Things NB-loT user equipment (UE) storing a previously received System Information Block information SIB and having a data sessions in a NarrowBand-lnternet of Things network.
  • UE user equipment
  • the invention also pertains to a device using said method.
  • Narrowband Internet of Things is a Low Power Wide Area Network (LPWAN) radio technology standard developed by 3GPP to enable a wide range of cellular devices and services.
  • LPWAN Low Power Wide Area Network
  • NB-loT focuses specifically on indoor coverage, low cost, long battery life, and high connection density. Mobility is based upon Radio Link Failure (RLF), meaning that, once a connection fails activities are started. Consequently, the NB-loT user equipment (UE) stays connected to the current serving cell unless the connection breaks.
  • RLF Radio Link Failure
  • NB-loT will be used in conjunction with LTE and 5G. So far there is a reestablishment process which schematically comprises the following steps: the user equipment stays connected until connection breaks and then, once the connection is broken, the user equipment starts to initiate neighbor cell measurements to find a new suitable cell and initiated connection setup to said new cell by indicating RLF. This cell search takes 10-20 seconds. Then the user equipment signals RRC connection re-establishment to the new Node and the new node tries to fetch the context from the old Node before the connection is resumed. In total this takes 30 seconds to one minute.
  • this is the base station that requests the UE to start neighbor cells measurements while giving a list of neighboring cells. This does not wait for any failure of the link. If the UE finds a cell, it then informs the base station. The cell can then thus forward the context to the next cell in order for the reestablishment to be shortly effective.
  • NB-loT While not being equipped with handover abilities, NB-loT is seen by some companies to become a GSM replacement. Hence improved mobility procedures are needed while respecting the restriction as defined in NB-loT. Handover as such is out of scope giving earlier standard agreements and also limited capability of NB-loT.
  • the invention also aims to improve the RLF re-establishment time by considering best effort assumptions in the network.
  • the present invention aims at improving the behavior of an NB-loT UE in case of mobility.
  • the present invention is defined, in its broadest sense, as a method to manage mobility prior Radio Link Failure in a NarrowBand-lnternet of Things NB-loT user equipment (UE) storing a previously received System Information Block information SIB and having a data sessions in a NarrowBand-lnternet of Things network, said method comprising the steps of, in the NB-loT user equipment: monitoring current transport conditions measurements of current data session connection with a current serving cell against an investigation threshold; monitoring a buffer status to evaluate the amount of data still needing to be transferred or received and initiating, itself, at the NB-loT user equipment, investigation measurements on neighbor cells of the NarrowBand-lnternet of Things network as listed in the stored System Information Block when at least the investigation threshold is crossed prior Radio Link Failure.
  • the user equipment is in charge of deciding to make the measurements at its own side. It makes the triggering of the measurements dependent of its own environment. Indeed, also in NB loT device it is possible to start neighbor cell measurements prior connection break according to today’s standard. This is a new procedure where the user equipment performs measurements prior RLF. However the decision when to perform these measurements depends on a threshold value upon which measurements are started. Said measurement can be a configuration value provided by the network considering the amount of overlap the current serving cell has to its neighbor cells, i.e. the threshold is a metric for a certain time prior RLF may occur.
  • the investigation measurements are performed during downlink gaps in NB-loT communication frame structure.
  • SIB system information block
  • the UE could start, based on the UE implementation of the invention, neighbor cell measurements prior RLF. It would be desirable by network manufacturers and operators intending to have NB-loT as a GSM replacement. The invention will enable minimal effort for the device while offering this possibility.
  • the UE evaluates the serving cell regarding to the service performed in the data session.
  • a service delay tolerant data session will get a very low investigation threshold for the UE not to trigger costly measurements while the service does not necessitate it. It enables the UE to answer the following questions: for the current service how much data do I still critically need to transfer and is the transfer speed still reasonably good?
  • the UE is aware that, for example during a software download, it can resume it at the point of a RLF later on without harm and it will not trigger the measurements.
  • the threshold will be set very low and no measurement will be triggered for a software download.
  • the investigation threshold will be very high and measurements will be triggered.
  • the investigation measurements are initiated only when an evaluated amount of data in the buffer status still needing to be transferred or received is above a buffer status threshold.
  • the user equipment also considers its buffer status, i.e. what is the amount of data it still needs to transmit and considering under current transport conditions the time this may take.
  • This embodiment enables the user equipment to estimate due to the buffer status how many data it has still to send or to receive at what speed. It can thus estimate how long it will take and then it can estimate whether the RLF may occur before the data session to terminate. If not finalized very soon, the user equipment uses gaps in the communication frame structure to perform measurements on neighbor cells it has read in the SIB. If it evaluates that the session will terminate before the RLF it does not trigger any measurements.
  • the user equipment can estimate the throughput that it achieves. When it is getting worse, more and more repetitions are required.
  • the user equipment is aware of that because the buffer status give the transferred payload. It enables to trigger the resource consuming measurements only in case the remaining data are expected not to be transferred before a radio link failure likely occurs.
  • the buffer status threshold is determined depending on the kind of user equipment and enables to take into account the nature of the user equipment and/or its environment.
  • the buffer status threshold will be very high, signifying that the measurements will not been triggered even if the quality of the link is getting worse and worse and even if it remains many data to transfer and even if the service would require a continuity of service.
  • the first threshold on the quality of the communication with the serving cell can also be set very low insuring that no measurement will ever be triggered.
  • buffer status thresholds are defined depending on the nature of the service as performed in the current data session.
  • the UE evaluates the serving cell regarding to the service performed in the data session. It is here noted that this feature is presented independently of the investigation threshold. However in equivalent embodiment to this, a single investigation threshold on the transport conditions but made dependent on a buffer status is addressed according to the invention.
  • the invention thus covers a variable investigation threshold, function of at least a buffer status.
  • the investigation threshold can be further made dependent on other status and thus being a function of a combination of several parameters relative to the nature of the UE, to the environment and to the service performed in the concerned data session.
  • the method comprises the further steps of, for the user equipment, determining internally a re-establishment target cell in case of Radio Link Failure occurs to current serving cell depending on investigation measurements on neighbor cells, and, for the user equipment, sending to the serving cell an information on the re-establishment target cell.
  • the method further comprises a step of, for the serving cell, indicating to the user equipment, that the re-establishment target cell is not a suitable candidate for re-establishment.
  • the method further comprises a step of, for the user equipment, resuming the neighbor cell search for a suitable candidate in case a non-suitable indication was provided by the serving cell for the information on the re-establishment target cell.
  • This features enables the user equipment to restart measurements to find a suitable cell.
  • the method further comprises a step of, for the user equipment, sending a user equipment identifier to the re-establishment target cell for subsequent establishment of a data session with the target cell.
  • This feature enables the next serving cell to be informed in advance of the establishment of a link with the user equipment as thus identified.
  • the method further comprises a step of, for the user equipment, sending a communication context including already correctly received or transmitted packets to the re-establishment target cell for subsequent establishment of a data session with the target cell.
  • the pre network context provisioning for RLF enables a quick and efficient reestablishment of the communication and avoids repetition in the packet transfer.
  • the user equipment can also indicate missing Packet Data Convergence Protocol Service Data Units (PDCP SDUs) by a binary matrix (TS36.223 section 5) etc...
  • PDU Protocol Data Unit
  • the data session is resumed by applying means for minimizing re-transmissions of exchanged data.
  • the data context evaluate which packets were not acknowledged and enables to only re-transmit those that were not acknowledged, or provide lacking report on Packet Data Convergence Protocol (PDCP) service data units.
  • PDCP Packet Data Convergence Protocol
  • the time for connection re-establishment with cause RLF can be further reduced besides just by performing measurements prior RLF occurs.
  • the current serving cell would start data forwarding via said connection, in UP/DL directions and indicate what was last successful received package. In a first approach this may refer to IP or non-IP packets, i.e. above the radio layers.
  • SDUs from PDUs forwarding of RLC/RRC layer would allow in case of RLF occurrence to re-assemble the packets correctly and not start in the new node with the entire last IP packet. It will also avoid to transmit again packets which were successfully received but nor confirmed or out-of a large PDU while only one SDU is missing, and hence avoid retransmission of said packets.
  • Such behavior besides controlled neighbor cell measurements and context forwarding instead of context fetch and including data packet forwarding reduces the outage time to a minimum possible. This feature enables a preparation of a communication link with the target re-establishment cell before any radio link failure occurs, i.e. the current serving BS provides UE context information towards the new suitable serving BS.
  • the method further comprises a step of, for the user equipment, sending a Radio Ressource Control connection re-establishment request to the target reestablishment cell with a cause “Radio Link Failure" for reestablishing communication in the NB-loT network for the user equipment.
  • Said request contains related information to the User Equipment context used in previous serving cell.
  • transport conditions measurements comprises measurements of at least one of the following parameters: a. delay-tolerance of the ongoing service b. QoS degradation of the current connection c. UE mobility speed. d. Applied CE level/number of repetitions e. CE level change f. Re-transmission rate g. a configuration value provided by the network considering the amount of overlap the current serving cell has to its neighbor cells.
  • the RACP reference signal can be used to evaluate the link reception quality at the UE as all the cells have the same power DB value at transmission.
  • the triggering of neighbor cells measurements by the user equipment is made dependent on service, on buffer status, on transport conditions and thus also on mobility of the UE. Measurements to be performed for NB-loT during connected mode can be considered as known. However, threshold control and usage of such measurements and reports are new and original features defined according to the invention.
  • the invention allows for improved connected mode mobility for NB-loT being more handover like, than nomadic mobility based on RLF. That topic is important for current developments wanting one version of NB-loT to achieve GSM like characteristic including mobility behavior.
  • the invention allows improved connected mode mobility for NB-loT being more handover like, than nomadic but respecting the reduced NB-loT parallel measurement capabilities in connected mode.
  • the method to manage mobility comprises the following steps, preliminarily to the establishment of the data session, of, for the serving cell: determining an investigation threshold for the data session; sending the determined investigation threshold in the system information block to the user equipment; and, for the user equipment, reading the investigation threshold to be used for the data session.
  • the present invention also relates to a NarrowBand-lnternet of Things NB-loT User Equipment (UE) storing a previously received System Information Block information SIB and being suitable to establish data sessions in a NarrowBand-lnternet of Things network and to manage mobility prior Radio Link Failure
  • said NB-loT user equipment comprising: a network measurement module to perform current transport conditions measurements of current data session connection with a current serving cell against an investigation threshold and investigation measurements on neighbor cells; a buffer status register to evaluate the amount of data still needing to be transferred or received
  • a mobility management module suitable to: monitor current transport conditions measurements of current data session connection with a current serving cell against an investigation threshold; monitor a buffer status to evaluate the amount of data still needing to be transferred or received and initiate, itself, at the NB-loT user equipment, investigation measurements on neighbor cells of the NarrowBand-lnternet of Things network as listed in the stored System Information Block when at least the investigation threshold is crossed prior Radio Link Failure.
  • Such a user equipment implements the method of the invention.
  • the invention also relates with a user equipment implementing any one of the above mentioned other features of the method of the invention.
  • NodeB broadcasts a threshold when measurements should be started for long lasting session, when the user equipment reaches threshold it evaluates whether worth to start measurements or not, if no measurements are started because one of the following reasons: short session, delay tolerant or static method ends. Otherwise the user equipment searches for re-establishment candidate. If found, it reports to serving cell, which forwards indication and user equipment context to new Node. Then, in case of RLF, the user equipment establishes connection to said node and context is already available and session immediately resumed. This procedures also takes ⁇ 30sec, but the interruption time is only a few seconds, as neighbor cell was searched in advance and once establishment starts user equipment context is already there.
  • one or more embodiments comprise the features hereinafter fully described and particularly pointed out in the claims.
  • Figure 1 illustrates the environment of a UE implementing the method of the invention
  • Figure 2A and 2B shows measurements and start of other cell search for LTE and for NB-loT
  • Figure 4 shows a time diagram of the method of the invention according to a preferred embodiment
  • Figure 5 shows a structure of a NB-loT communication frame where the measurements of the invention can occur.
  • Figure 1 schematically shows a User Equipment UE in mobility between two base stations B1 and B2 having NBIoT capabilities. Their respective areas of service are illustrated by ovals A1 and A2.
  • the user equipment UE While migrating from the area A1 to the area A2, the user equipment UE, being in a data session with the base B1 , suffers from a lowering of the quality of its link with base B1.
  • the UE Prior establishing the data session in course, the UE received from the base B1 a System Information Block SIB that it has stored in an internal memory IM.
  • SIB System Information Block
  • the user equipment UE has thus a data session with B1 and earlier read corresponding SIBs, including neighbor cell list and, in a preferred embodiment, an investigation threshold when evaluation should be started.
  • the investigation threshold is thus determined and provided per indicated node carrier frequency by the base station B1 . It is here noted that the investigation threshold can also be a general value in some embodiments.
  • the threshold provided by the network is advantageously related to the network deployment/layout.
  • the network knows whether there are neighbor cells around and from which reception level onwards it makes sense for a user equipment to scan for them.
  • radio signal power decreases from emitting base station in a radial way and, for mobility, it is needed to monitor neighbor cells, report them and perform handover, so cells have a certain overlap.
  • NB-loT has in principle same overlap, even a bit larger due to higher power. This is illustrated on figure 2A and figure 2B where a decrease of radio link power is shown respectively in LTE technology and in NB-loT technology in relation with a Sintrasearch threshold of the prior art is shown. It makes sense in said overlap area to start the measurements.
  • the network sets the threshold to a value where the neighbor cell should have same magnitude of power as serving cell.
  • Said threshold setting is known from idle mode mobility, i.e. Sintrasearch and Sintersearch. However, this is not sufficient for RLF mobility as it cannot differentiate the various user equipment’s and their needs.
  • the NBIoT network sets a threshold that can be similar to the threshold already used in other contexts, but once user equipment reaches said threshold, it is the one to decide whether to perform measurements or not.
  • Several trivial ways how to define a threshold when to start the measurements this is known from other RRC states but the exact value depends on the network layout and cell deployment.
  • the value is adapted for outdoor devices needing mobility and will not help for indoor.
  • An indoor device would always be below said threshold and it thus needs said user equipment mechanism for connected mode mobility/RLF. Also when hitting said threshold and moving on, it still takes a while till signal disappears and connection breaks so, for short transmissions, it is also not useful for NB-lot to start measurements.
  • these thresholds may be sufficient for idle mode, where all UEs have same target, i.e. maintaining camping to one base station.
  • these thresholds may be sufficient for idle mode, where all UEs have same target, i.e. maintaining camping to one base station.
  • short session, long session delay tolerant data exchange or others there would be a need for different thresholds, if it would not be up to the UE to decide on when to start the measurements because these thresholds are cell specific and cannot differentiate UEs having different needs;
  • Figure 3 shows the evolution of the quality of the link of the UE with the base B1 through a measurement M(B1).
  • This measurement M(B1) can be one or a combination of the below listed parameters observed while a UE is linked with a base: a. Delay-tolerance of the ongoing service b. QoS degradation of the current connection c. UE mobility speed. d. Applied CE level/number of repetitions e. Coverage Enhancement level change f. Re-transmission rate g. An evolving configuration value provided by the network considering the amount of overlap the current serving cell has to its neighbor cells.
  • the quantity is a measurement as defined in TS36.214 section 5.1.26 Narrowband Reference Signal Received Power (NRSRP) or 5.1.27 Narrowband Reference Signal Received Quality (NRSRQ) where applicability would need to be extended for RRC-Connected mode so threshold is a dB or dBm value as defined with respect to the reference signal.
  • NRSRP Narrowband Reference Signal Received Power
  • NRSRQ Narrowband Reference Signal Received Quality
  • threshold is a dB or dBm value as defined with respect to the reference signal.
  • a measurement based on reference signal so far only existing for idle mode, is used for connected mode. It is here noted that the measurement M(B1) is schematically shown as decreasing but it could be as well an increasing parameter as soon as it witnesses of the quality of the link between the user equipment and the current serving base B1.
  • An investigation threshold IT(S) is defined on the measurement M.
  • Simplest way is to compare measured values of NPRSCP or NPRSRQ for the serving cell and how they decrease and what is defined for said cell with respect to suitability criteria for the serving cell.
  • radio link monitoring is in general known, for example TS36.133 Chapter 7.6 and especially 7.6.1.
  • the user equipment UE When the user equipment UE receives a radio link, it shall be able to receive and stay connected till a lower threshold is reached which leads to RLF, however a suitable threshold prior loosing said link is advantageously an upper boundary X-dB above said RLF connection loss threshold.
  • an investigation measurement M(B2) is started for at least one other base, here B2, as listed in the previously stored SIB. If the user equipment measures the serving cell being below the threshold and has evaluated to start neighbor cell measurements, e.g. large amount of data still in the buffer, or the network indicated a buffer status non-zero, i.e. the buffer at base station side still full, and has found a neighbor cell above said threshold, the Physical Cell ID (PCID) is reported by the user equipment to the serving base station.
  • PCID Physical Cell ID
  • the NB-lot user equipment does not read SIBs during data session but the SIB was read prior starting the data session and as no RLF occurred, the SIBs previously read in idle mode are still valid. Information it has stored are, at least, neighbor cell information. The user equipment also knows the investigation threshold to start the investigation.
  • the base station B1 let the UE managing the triggering of the neighbor cells measurements but the triggering is based on thresholds that are defined and controlled by the base station. It enables the base station to adjust a threshold to be applied for a specific service.
  • the user equipment starts measurements upon next gap and, once the user equipment has found a suitable cell as re-establishment candidate if RLF would occur now, the user equipment UE reports said cell to the serving cell B1.
  • the current serving cell receives the potential candidate in which the user equipment would try to reuse the connection once broken after RLF.
  • the base station B1 Upon receiving such cell, the base station B1 would contact said cell via an X2/N2 interface towards said cell, eNodeB-eNodeB.
  • the base station B1 indicates to base station B2 possible candidate approaching with RLF re-establishment. Via said interface, it would preferably provide the UE ID and context indicating that said UE may resume its context in said cell and ask for a context fetch.
  • node B1 may also mirror data packets provided to the user equipment to node B2 as a data forwarding or provides reports which packets were successfully received from the UE
  • node B2 Upon receiving user equipment indication in node B2, node B2 can confirm being ready to take over the context, or indicate that it is restricted/barred or overloaded. Also, if this is the case, such information may be transferred also to user equipment indicating that base station B2 not suitable for RLF, i.e. to avoid unsuccessful establishment attempts by the user equipment.
  • the user equipment may not be able to read any neighbor cell SIBs during the ongoing data session with the serving cell even when being on same frequency, due to its limited capabilities. Only after RLF has occurred, the user equipment would start reading SIBs of the target cell and it would become aware that said cell is not a suitable re-establishment candidate as it is barred or for operator use only. And hence, in such a situation, the user equipment needs to start a search again. However, doing previously measurements to evaluate several candidates as potential re-establishment candidates, for the case one of them would be barred, would also be a waste of energy.
  • the proposed indication on potential re-establishment candidate to the still serving base station to avoid such failures is also an advantageous enhancement.
  • the base station may indicate to the user equipment to proceed to search another cell and continue the search.
  • base station B1 can indicate to base station B2 that data session with the user equipment ended.
  • the user equipment may retrigger said search and find a new cell B3, which accordingly would be reported to the serving base station B1.
  • the serving base station B1 may indicate to this base station B3 that it is now suitable candidate and may also inform the previously targeted base station B2 that it is no more candidate for context re-establishment for said user equipment.
  • the user equipment UE selects prior detected node B2 and performs re-establishment with cause RLF. It thus provides its identity and the identity of the previous serving node B1. Then node B2 indicates context available, resumes the session and, if available, indicates what was the last packet correctly received by node B1 from the user equipment and forwarded and the UE indicates what was last successful received packet from node B1 .
  • FIG 3 is illustrated a case where a switch from base B1 to base B2, illustrated by an arrow, is effective before any RLF. This enables to get continuity of service which can be a requirement for NB-loT to be extended to other applications than the ones it is currently used for.
  • the investigation measurements are advantageously triggered only in case there is still a minimum quantity of data to be still transmitted.
  • the invention also concerns the case where another threshold on the quantity of data is also monitored and crossed.
  • a data session is requested by a user equipment UE at a serving cell, here B1.
  • the user equipment UE receives NRSRP/NRSQ from cell B1 being above a suitability criteria and momentary no better cell is found. With the establishment of the data session, the user equipment UE camps on cell B1 and, in a step E2, receives and stores related broadcast information/SIB from the serving cell B1 listing among other information a list of neighbor cells, here notably B2 and Bi for the example of figure 1.
  • the system information block includes a threshold for NB-loT when sensible to perform neighbor cell measurements. Then the data session occurs, illustrated by E3. The user equipment UE is thus in a data exchange session with the network and the serving cell B1 is above said investigation threshold IT(S).
  • measurements M(B1) relative to the link with cell B1 are performed at the UE.
  • Those measurements M(B1) are monitored, illustrated by a step E4 on figure 4, against the threshold IT(S) that defines a limit in the quality of the link with the serving cell B1 under which measurements on neighboring cells as listed in the SIB could be triggered.
  • the threshold IT(S) that defines a limit in the quality of the link with the serving cell B1 under which measurements on neighboring cells as listed in the SIB could be triggered.
  • the data session is pursued without any other measurement.
  • the measurements on neighboring cells B2 and Bi listed in the SIB are started as soon as the threshold T(S) has been crossed (case Y), thus once used radio link gets below threshold.
  • a buffer status BS of the data to be transmitted or received is compared to another threshold IT(BS).
  • the user equipment UE evaluates whether to perform neighbor cell measurements: is the UE static? If yes, do not do anything. Are the data delay tolerant? If yes, nothing is performed by the user equipment UE. If both were no, the user equipment UE estimates whether session will be finished prior radio link will fail. The buffer status low or high in the user equipment and serving cell B1 , the degradation speed of the radio link or the increase in data repetitions are tested in steps E5 and E6.
  • radio link will fail in 10 seconds if proceeding to degrade like currently, data transmission will take at least more than 10 seconds giving current speed or considering even degrading data transmission speed with degrading radio link.
  • this evaluation is negative, additional measurements with neighbor cells are started according to cell received in system information.
  • the neighboring cell B2 is detected by the user equipment UE as a suitable and best fitted cell for a link to be established before radio link failure.
  • the user lequipment UE informs the serving cell B1 of the identified best neighboring cell B2 to take over in case of RLF as a target cell. Then, the serving cell B1 informs the target cell B2 that it may be candidate for reestablishment candidate for the user equipment UE and provides at least an identifier ID(IIE) of the user equipment UE in a step E9.
  • the base station B1 may do the following:
  • the cell B1 then remarks that the user equipment UE disappeared and optionally wraps-up data in a step E9’, i.e. provides non-acknowledged DL data, i.e. data send by the base station in downlink but not confirmed by the UE yet to the target cell B2 and informs the target cell B2 on correctly received UL packets but not acknowledged.
  • non-acknowledged DL data i.e. data send by the base station in downlink but not confirmed by the UE yet to the target cell B2 and informs the target cell B2 on correctly received UL packets but not acknowledged.
  • the user equipment UE will send information/summary on which packets in DL were last correct received and hence the new base station knows which of the forwarded data packets from BS1 it needs to transmit again and also indicates in case of UL packets received, which was not acknowledged yet.
  • the UE If the UE does not receive an indication that the packet was already correctly received in the previous cell, it will start transmission again or in case of HARQ resume the transmission and it will continue with same packet in different format. At the same time the cell B2 will know which packets were sent in DL but where confirmation is outstanding. Either the UE indicates that these packets were already correctly received in the previous cell (confirmation), or B2 will resume their transmission and provide them again.
  • the user equipment UE receives and reads required SIBs from cell B2 to communicate with B2 in step E10.
  • the user equipment then performs connection re-establishment procedure towards the cell B2 with cause RLF re-establishment in following steps.
  • a step E11 the user equipment communicates with the new target cell B2 and requests re-establishment cause “RLF” including its identity which has to match with the identity received by the target cell B2 in step E9.
  • the UE may optionally include data related to the user equipment UE data session i.e. which was the last block correctly received from BS1 but where no confirmation was send out. This is an optional enhancement similar to E9’ to avoid re-sending of already correct received packets by the B2.
  • the data session is resumed by transmission of an ACK sent by cell B2 to the user equipment.
  • Data exchanges start in a step E13 either by starting to transmit with packets not being acknowledged by the previously cell B1 (UpLink case) or by the user equipment UE (DownLink case).
  • session will be resumed based on said information.
  • Figure 5 shows a typical time structure for a communication frame where it is possible for the UE to make measurements between active data transmission. Such measurements can be performed during discontinuous reception gaps (DRX).
  • DRX discontinuous reception gaps
  • the UE is scheduled in a first slot SL1 and receives some data in next slots.
  • a DRX- Inactivity timer DRX-InT is launched while the UE monitors PDCCH. It expires here after four slots as illustrated by a star on figure 4 and a long DRX cycle starts waiting for data.
  • an onDuration Timer oDT runs where the UE monitors PDCCH.
  • the onDuration Timer oDT is just a fraction of the DRX long cycle, where user equipment UE needs to receive something due to errors in previous transmission/reception. But afterwards there is a real DRX time, where measurement can be placed. It thus follows a period of opportunity for DRX where neighbor cell measurements NCM can take place as illustrated on figure 4.
  • the invention takes the opportunity of existing gaps in frame structure to make measurements when the decision according to the invention is taken.
  • the UE is in any case adapted to make measurements with neighboring cells according to the invention as it is equipped with the necessary features to make them in idle mode.
  • connected mode as seen on figure 4, there is time to do the measurements in NB-loT devices’ communication frames when the device receives or transmit data. Indeed the device get certain time in-between transfer of data also in connected mode because the device needs to repeat all the things and in this time, the device can do then the measurements of the invention also in connected mode and while remaining NB-loT standard compliant. For example the device needs to send the same packet several times because it is in bad communication conditions, it will get 12 times to get the answer and in-between there are gaps as seen in the above presented frame structure. When no measurements are done according to the invention, the device simply does not do anything.

Landscapes

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

Abstract

La présente invention concerne un procédé de gestion de mobilité avant une défaillance de liaison radio dans un équipement utilisateur (UE) de l'Internet des objets à bande étroite NB-IdO stockant un bloc d'informations de système, SIB, précédemment reçu et ayant une session de données dans un réseau de l'Internet des objets à bande étroite, ledit procédé faisant appel aux étapes suivantes de, dans l'équipement utilisateur (UE) NB-IdO : - surveillance de conditions de transport courantes de connexion de session de données courante avec une cellule de desserte courante (B1) par rapport à un seuil d'investigation ((IT(S)) ; - surveillance d'un état de tampon pour évaluer la quantité de données qui doivent encore être transférées ou reçues et - initiation, lui-même, au niveau de l'équipement utilisateur (UE) NB-IdO, de mesures d'investigation sur des cellules voisines (B2, Bi) du réseau de l'Internet des objets à bande étroite tel qu'indiqué dans le bloc d'informations de système stocké lorsqu'au moins le seuil d'investigation (IT(S)) est franchi avant une défaillance de liaison radio.
EP21823837.6A 2020-12-03 2021-11-30 Gestion de mobilité améliorée pour équipement utilisateur nb-ido avant une défaillance de liaison radio Pending EP4256841A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP20211620.8A EP4009692A1 (fr) 2020-12-03 2020-12-03 Gestion améliorée de mobilité d'un équipement d'utilisateur nb-iot avant d'une défaillance de liaison radio
PCT/EP2021/083614 WO2022117580A1 (fr) 2020-12-03 2021-11-30 Gestion de mobilité améliorée pour équipement utilisateur nb-ido avant une défaillance de liaison radio

Publications (1)

Publication Number Publication Date
EP4256841A1 true EP4256841A1 (fr) 2023-10-11

Family

ID=73698680

Family Applications (2)

Application Number Title Priority Date Filing Date
EP20211620.8A Withdrawn EP4009692A1 (fr) 2020-12-03 2020-12-03 Gestion améliorée de mobilité d'un équipement d'utilisateur nb-iot avant d'une défaillance de liaison radio
EP21823837.6A Pending EP4256841A1 (fr) 2020-12-03 2021-11-30 Gestion de mobilité améliorée pour équipement utilisateur nb-ido avant une défaillance de liaison radio

Family Applications Before (1)

Application Number Title Priority Date Filing Date
EP20211620.8A Withdrawn EP4009692A1 (fr) 2020-12-03 2020-12-03 Gestion améliorée de mobilité d'un équipement d'utilisateur nb-iot avant d'une défaillance de liaison radio

Country Status (3)

Country Link
EP (2) EP4009692A1 (fr)
CN (1) CN116830646A (fr)
WO (1) WO2022117580A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US11825362B2 (en) * 2021-03-26 2023-11-21 Qualcomm Incorporated Neighbor cell measurements for narrowband communications

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2011123744A1 (fr) * 2010-04-02 2011-10-06 Interdigital Patent Holdings, Inc. Procédures et états de faible mobilité
US10225785B2 (en) * 2016-06-08 2019-03-05 Qualcomm Incorporated Wireless device initiated handover
US10813028B2 (en) * 2016-07-21 2020-10-20 Kt Corporation Method for performing mobility process of NB-IoT terminal, and apparatus therefor
KR102656957B1 (ko) * 2016-12-16 2024-04-16 삼성전자 주식회사 무선통신 시스템에서 고속 이동을 위한 측정 방법 및 장치

Also Published As

Publication number Publication date
EP4009692A1 (fr) 2022-06-08
WO2022117580A1 (fr) 2022-06-09
CN116830646A (zh) 2023-09-29

Similar Documents

Publication Publication Date Title
US11051219B2 (en) Method and apparatus for controlling mobility for cell having small cell service area in mobile communication system
US11985564B2 (en) Adapting a mobile network
CN102860075B (zh) 无线电链路故障情况下的改进切换
US9125102B2 (en) Method of transmitting measurement report in wireless communication system
US9031564B2 (en) Handover robustness in cellular radio communications
RU2640793C2 (ru) Способ передачи истории посещения ячеек и беспроводное оборудование для его осуществления
US20120064886A1 (en) Method of logging measurement result at handover failure in wireless communication system
US11184938B2 (en) Method and device for requesting RRC connection
US20180070331A1 (en) Method and apparatus for reducing paging signaling
CN105379324A (zh) 用于发送小区受访历史的方法及其无线设备
US20160374006A1 (en) Communication system
US10136366B2 (en) Method and apparatus for terminal to perform frequency measurement on basis of cell specific priority
US20180132153A1 (en) Method and apparatus for performing cell reselection procedures for load distribution
US10917794B2 (en) Method and device for terminal calculating redistribution range in wireless communication system
EP4009692A1 (fr) Gestion améliorée de mobilité d'un équipement d'utilisateur nb-iot avant d'une défaillance de liaison radio
KR20090124788A (ko) 이동 통신 시스템에서 핸드오버 방법 및 장치
Gelabert A Simulation Study on LTE Handover and the Impact of Cell Size

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20230605

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)