WO2013139778A1 - Continuité de service dans des situations de transfert dans des systèmes de communication cellulaire - Google Patents

Continuité de service dans des situations de transfert dans des systèmes de communication cellulaire Download PDF

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Publication number
WO2013139778A1
WO2013139778A1 PCT/EP2013/055672 EP2013055672W WO2013139778A1 WO 2013139778 A1 WO2013139778 A1 WO 2013139778A1 EP 2013055672 W EP2013055672 W EP 2013055672W WO 2013139778 A1 WO2013139778 A1 WO 2013139778A1
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Prior art keywords
base station
user equipment
service
indication
target base
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PCT/EP2013/055672
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English (en)
Inventor
Mai-Anh Phan
Ingrid Nordstrand
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Telefonaktiebolaget L M Ericsson (Publ)
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Publication of WO2013139778A1 publication Critical patent/WO2013139778A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W36/00—Hand-off or reselection arrangements
    • H04W36/08—Reselecting an access point
    • 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
    • H04W36/0007—Control or signalling for completing the hand-off for multicast or broadcast services, e.g. MBMS

Definitions

  • the present invention relates to methods for supporting continuity of a service in handover situations in a cellular communication system and to corresponding nodes of the cellular system.
  • UEs User Equipments
  • RAN Radio Access Network
  • CNs Core Networks
  • a user equipment is a mobile terminal by which a subscriber can access services offered by an operator's network.
  • the user equipments may be for example communication devices such as mobile telephones, cellular telephones, laptops or tablet computers, sometimes referred to as surf plates, with wireless capability.
  • the user equipments may be portable, pocket-storable, hand-held, computer-comprised, or vehicle -mounted mobile devices, enabled to communicate voice and/or data, via the radio access network, with another entity, such as another mobile station or a server.
  • User equipments are enabled to communicate wirelessly in the cellular network.
  • the communication may be performed e.g. between two user equipments, between a user equipment and a regular telephone and/or between the user equipment and a server via the radio access network and possibly one or more core networks, comprised within the cellular network.
  • the cellular network covers a geographical area which is divided into cell areas. Each cell area is served by a base station, e.g. a Radio Base Station (RBS), which sometimes may be referred to as e.g. "eNB”, “eNodeB”, “NodeB”, “B node”, or BTS (Base Transceiver Station), depending on the technology and terminology used.
  • RBS Radio Base Station
  • a cell is the geographical area where radio coverage is provided by the base station at a base station site.
  • One base station, situated on the base station site may serve one or several cells.
  • each base station may support one or several communication technologies.
  • the base stations communicate over the air interface operating on radio frequencies with the user equipments within range of the base stations.
  • radio network controller e.g. a Radio Network Controller (RNC) in Universal Mobile Telecommunications System (UMTS)
  • RNC Radio Network Controller
  • UMTS Universal Mobile Telecommunications System
  • BSC Base Station Controller
  • GSM Global System for Mobile Communications
  • MBMS Multimedia Broadcast Multicast Service
  • GSM Global System for Mobile communications
  • UTRAN UMTS Terrestrial Radio Access Network
  • E-UTRAN evolved UTRAN
  • MBMS For MBMS, broadcast services are generally offered within a large geographic area, consisting of one or more cells. MBMS services can be distributed in target regions by using so-called MBMS Service Areas as e.g. defined in 3 GPP TS 23.003 V9.1.0.
  • An MBMS Service Area consists of one or more MBMS Service Area Identities (MBMS SAIs).
  • An MBMS SAI shall identify a group of cells within a Public Land Mobile
  • a cell can belong to one or more MBMS SAs, and therefore is addressable by one or more MBMS SAIs. Since all cells within an MBMS SAI distribute the same set of services, the spectral efficiency of MBMS transmission can be optimized by applying MBMS single frequency network (MBSFN) operation, which means that identical data is transmitted on the same time -frequency radio resources from each cell.
  • MBSFN single frequency network
  • the cells that offer the same set of MBMS services and the same scheduling of MBMS service sessions belong to one MBSFN area. Furthermore, one requirement is that cells belonging to the same MBSFN area have to be tightly synchronized (e.g. in the order of micro-seconds). From a terminal perspective all signals transmitted from the cells within the MBSFN area combine over the radio resulting in an improved signal to interference and noise ratio (SINR).
  • SINR signal to interference and noise ratio
  • RAN WG 2 Radio Access Network Working Group 2
  • LTE Log Term Evolution
  • RRC Radio Resource Control
  • MBMSInterestlndication message to the network, e.g. to the eNodeB as part of the network.
  • This message contains the MBMS frequency or MBMS frequencies, on which the UE is interested or is already receiving MBMS services.
  • Handover scenarios cover a handover of a user equipment from a source base station to a target base station or from a source cell to a target cell.
  • the target eNB will not be aware of the UE's MBMS interest.
  • the target eNB In order to inform the target eNB about the UE's MBMS interest, there are two options as described in the 3GPP contribution R2-120512, entitled "Open issues for MBMSInterestlndication," 3GPP TSG-RAN WG2 Meeting #77.
  • the UE needs to re-send the MBMS interest indication message to the target eNB.
  • the source eNB forwards the MBMS interest indication message to the target eNB.
  • a service such as the MBMS service
  • Service continuity shall further be improved.
  • nodes such as base stations
  • interworking of the respective nodes such that service continuity is supported at a reasonable level of signaling overhead is of importance.
  • a method for supporting service continuity in a cellular communication system comprises a source base station, a target base station and a user equipment to be handed over from the source base station to the target base station.
  • the method comprises the steps: the target base station receiving, from the source base station, an indication that the user equipment is interested in receiving a service; the target base station checking the received indication; and the target base station indicating whether the target base station requests the user equipment to send the indication that the user equipment is interested in receiving the service to the target base station.
  • a base station for supporting service continuity in a cellular communication system.
  • the cellular system comprises a source base station, the base station and a user equipment to be handed over from the source base station to the base station, the base station comprises a receiver for receiving, from the source base station, an indication that the user equipment is interested in receiving a service and a processor for checking the received indication and indicating whether the target base station requests the user equipment to send the indication that the user equipment is interested in receiving the service to the target base station.
  • a method in a user equipment for supporting service continuity in a cellular communication system comprises a source base station, a target base station and the user equipment to be handed over from the source base station to the target base station.
  • the method comprises the steps: receiving an indication of the target base station whether the target base station requests the user equipment to send the indication that the user equipment is interested in receiving a service to the target base station; and on the basis of the received indication, determining whether to send the indication that the user equipment is interested in receiving a service to the target base station.
  • a user equipment for supporting service continuity in a cellular communication system comprises a source base station, a target base station and the user equipment to be handed over from the source base station to the target base station.
  • the user equipment comprises: a receiver for receiving an indication of the target base station whether the target base station requests the user equipment to send the indication that the user equipment is interested in receiving a service to the target base station; and a processor for
  • Fig. 1 schematically illustrates an exemplary relationship between MBMS Service Areas, MBMS Service Area Identities and MBSFN areas.
  • Fig. 2 shows a message diagram for illustrating an example of a message flow comprising a service interest indication.
  • Fig. 3 shows a message diagram for illustrating an example of a message flow comprising a service interest indication.
  • Fig. 4 schematically illustrates handover situations in which embodiments of the invention are applied.
  • Fig. 5 shows a flow chart for illustrating a method according to an embodiment of the invention.
  • Fig. 6 schematically illustrates different nodes of a cellular communication system according to embodiments of the invention.
  • Fig. 7 shows a flow chart for illustrating a method according to an embodiment of the invention.
  • Fig. 8 schematically illustrates a base station according to an embodiment of the invention.
  • Fig. 9 schematically illustrates a base station according to one embodiment of the invention.
  • Fig. 10 shows a flow chart for illustrating a method in a user equipment according to an embodiment of the invention.
  • Fig. 1 1 schematically illustrates a user equipment according to an embodiment of the invention.
  • Fig. 1 illustrates a relationship between MBMS Service Areas, MBMS Service Area Identities (MBMS SAIs), and MBSFN areas.
  • An MBMS Service Area A comprises MBMS SAI #1 and MBMS SAI#2.
  • MBMS SAM covers MBSFN areas #1 and #2.
  • the MBMS services that are provided in MBSFN area $1 and $2, belonging to the MBMS SAI # 1 do not have to schedule the MBMS data synchronously; the synchronization requirement is only valid within the same MBSFN area.
  • MBSFN area #1 operates e.g. on carrier frequency fl, and MBSFN area $4 could cover carrier frequency f2. Both MBSFN areas #1 and #4 cover the same geographic area.
  • MBMS services that are provided via MBSFN are generally provided only on one frequency, while multiple frequencies will be deployed in a geographic area to cope with increasing traffic, i.e. identical content is not duplicated on the other frequencies.
  • 3GPP RAN WG 2 (Working Group 2) has agreed for LTE Rel-11 that the following information is broadcast from the network to the UE (see also R2- 120927, entitled "Stage 2 agreements on service continuity for MBMS for LTE").
  • MBMS cells indicate in their system information the MBMS SAIs to which they belong.
  • MBMS and non-MBMS cells indicate in their system information the MBMS SAIs of neighbor frequencies (it is for further study if cells for a Closed
  • Subscriber Groups i.e. CSG cells
  • Pre-Rel-11 cells and cells that are not within the geographic area of any MBMS Service Area do not broadcast any MBMS SAIs.
  • the MBMS interest indication message may be used by the network to avoid inter- frequency handovers or reconfiguration of the serving cells which would interrupt the MBMS service reception, which would result in degraded user perception of the MBMS service.
  • Inter- frequency handovers can be triggered by the network for load balancing purposes, and serving cell reconfigurations could be initiated by the network to allow for more efficient unicast transmission.
  • the UE When the UE is interested in or is receiving MBMS services and knows that these services are provided in the UE's current geographic location based on the MBMS SAIs that are broadcast in the serving cell's system information, the UE sends the MBMS interest indication message to the serving cell when it is already in RRC connected mode or moves from RRC idle to RRC connected mode, i.e. after RRC connection setup.
  • the MBMS interest indication message is sent to the serving cell whenever the UE's interest changes with regard to the signaled information within the MBMS interest indication message.
  • Fig. 2 shows an inter-eNB handover procedure for a UE 201 moving from a source eNB 202 to a target eNB 203.
  • Source eNB 202 and target eNB 203 are connected via an X2/S1 interface 204.
  • the source eNB 202 selects the target cell operated by the target eNB 203 and informs the target eNB 203 about its decision in a HandoverPreparationlnformation message 205.
  • the target eNB 203 decides about the UE's RRC connection
  • An RRCConnectionReconfiguration message 207 which includes an Information Element (IE) MobilityControlInfo to inform the UE about the network's handover decision, is sent transparently from the target eNB 203 via the source eNB 202 to the UE 201 and is carried within a HandoverCommand message 206, which is sent from the target eNB 203 to the source eNB 202 via X2/S1 interface 204.
  • IE Information Element
  • HandoverCommand message 206 contains the entire DL-DCCH-Message including the RRCConnectionReconfiguration message used to perform handover to E-UTRAN, generated (entirely) by the target eNB 203.
  • the target eNB 203 may decide to reconfigure the SCells, i.e. a secondary serving cell, independently of the HandoverPreparationlnformation message 205 received from the source eNB 202 via the X2/S1 interface 204. If the MBMS frequency is not covered by the reconfigured band combination, the UE 201 cannot continue MBMS reception on the MBMS frequency. After the handover procedure, the UE 201 re-sends the MBMS interest indication message 208 to the target eNB 203.
  • the UE 201 unconditionally sends the MBMS interest indication message 208 to the target eNB 203 without reading relevant system information, signaling resources will be wasted mainly in the uplink, but also in the downlink control channel to provide the uplink grant to the UE.
  • the UE 201 If the UE 201 reads the system information of the 'target cell', which is the UE's new serving cell after the handover procedure is finalized, some additional delay will be introduced before the UE is allowed to send the MBMS interest indication to the network. Meanwhile, the network may - for the reasons described above - decide to trigger an inter-frequency handover or initiate a reconfiguration of secondary serving cells (SCells), which may interrupt the MBMS service reception. In order to avoid unnecessary uplink signaling, the UE 201 should only send the MBMS interest indication message after the handover to the target eNB 203 when the target eNB 203 supports the reception of the MBMS interest indication message. In order to find out that MBMS service continuity is supported by the target eNB 203, the UE 201 may read the target cell's system information.
  • SCells secondary serving cells
  • Fig. 3 shows an inter-eNB handover procedure for a UE 301 moving from a source eNB 302 to a target eNB 303.
  • existing messages are extended to provide relevant information to target eNB 303, which allows the target eNB 303 to consider the UE's MBMS interest in its decisions to reconfigure the RRC connection.
  • the MobilityControlInfo IE 305 which is generated in the target eNB 303, can be extended to inform the UE 301 whether it is supposed to send the MBMSInterestlndication message 306 to the target eNB 303,
  • the source eNB 302 forwards the
  • MBMSInterestlndication message 307 is added to the HandoverPreparationlnformation message 308 sent via the X2/S1 interface 304.
  • This new MBMS interest indication requires additional specification which affects X2/S1 message forwarding.
  • the UE 301 cannot expect that the MBMS interest indication is always forwarded to the target eNB 303. If the UE 301 moves from an eNB #1 which supports MBMS service continuity to an eNB #2 not supporting MBMS service continuity and then moves to another eNB #3 supporting the MBMS service continuity, the MBMS interest will not be available in eNB #3, and additional specification is needed to indicate to the UE that it needs to transmit the MBMS interest indication to eNB #3.
  • the target eNB 303 Since the target eNB 303 generates the RRCConnectionReconfiguration message 309, which contains the mobilityControlInfo IE 310 and is transmitted transparently from the source eNB 302 to the UE 301 during the handover procedure, the target eNB 303 can indicate its support for MBMS service continuity in the RRCConnectionReconfiguration message 309.
  • the support for service continuity may generally also be indicated within another message or information element.
  • the discussed messages and information elements represent examples which are suited to transport the relevant information in a particular communication system.
  • the mobilityControlInfo IE can be extended by a flag, e.g. an mbms- interestlndicationRequest flag, to indicate to the UE that it shall re-send the MBMS interest indication immediately after the handover procedure. If the target eNB is not within any MBMS Service Area, the flag does not need to be included. Alternatively, the flag can be set to FALSE to indicate to the UE that it shall not re-send the MBMS interest indication to the target eNB to save signaling resources.
  • a flag e.g. an mbms- interestlndicationRequest flag
  • the target eNB can add a flag, e.g. an mbms-InterestlndicationRequest flag, in the MobilityControlInfo IE.
  • the UE knows that the target eNB is a pre-Rel-11 eNB or does not support this Rel-11 MBMS feature. Thus, the UE also knows that it is not supposed to send the MBMSInterestlndication message. If this flag is available and e.g. set to FALSE, the UE knows that it is not supposed to re- send the MBMSInterestlndication message immediately after the handover procedure. This could e.g. be the case when the target eNB does not provide any MBMS services or when it belongs to a different set of MBMS SAIs than the source eNB. If this flag is set to TRUE, the UE may send the MBMSInterestlndication message before reading relevant system information.
  • the IE MobilityControlInfo includes parameters relevant for network controlled mobility to/within E-UTRA.
  • the MobilityControlInfo IE is defined in 3 GPP TS 36.331.
  • this flag can be added in the MobilityControlInfo IE.
  • the flag does not need to be added directly on the first level within the
  • MobilityControlInfo IE but it could alternatively be added on a lower level, e.g. to the IE RadioResourceConfigCommon, which is transferred within the MobilityControlInfo IE. If the mbms-InterestlndicationRequest flag is not provided in the MobilityControlInfo IE, the UE can derive from its absence that the target eNB either does not support the Rel-1 1 MBMS service continuity feature or that the target eNB does not belong to or is not in the vicinity of any MBMS Service Area.
  • the UE will (re-)send the MBMSInterestlndication message to the target eNB immediately after finalizing the handover procedure. Since the flag is provided, the UE also knows implicitly that the target eNB supports the Rel-11 MBMS service continuity feature.
  • the UE does not re-send the MBMSInterestlndication message to the target eNB immediately after finalizing the handover procedure, but knows that the target eNB in general supports MBMS service continuity, and that it may send the MBMSInterestlndication message upon changes at a later time instance.
  • the target eNB may set the mbms-InterestlndicationRequest to FALSE when it has already received the MBMSInterestlndication message from the source eNB. It may also set the flag to FALSE when the source eNB belongs to a different set of MBMS service area identities or MBSFN areas.
  • the transmission of the MBMSInterestlndication is not time critical, and the UE can send its interest indication at a later stage, e.g. after reading system information from the target eNB.
  • Fig. 4 illustrates a movement of a UE 401 within a network 403.
  • eNBs can cover multiple frequencies.
  • Fig. 4 only the cells that belong to the MBMS SAI providing the UE's MBMS service(s) of interest are shown.
  • So MBMS SAI#1 is identical to MBSFN area #1.
  • the border of MBSFN area #1 is highlighted by a thick line 402.
  • all cells belonging to MBSFN area #1 provide the same set of MBMS services via MBSFN including the UE's MBMS service of interest.
  • the MBSFN area #1 consists of "Rel-11" eNBs that support the MBMS interest indication message, and so-called “Rel-9/10" eNBs that do not support this feature introduced for LTE MBMS Rel-11.
  • White cells are outside of any MBMS service area.
  • the cells with the checkerboard pattern belong to MBMS SAI#2, i.e. MBSFN area #2.
  • the respective target eNB supports MBMS service continuity. This is the case at points A, B and D.
  • the eNB sets the mbms- InterestlndicationRequest flag within the mobilityControlInfo IE to TRUE in order to request the UE to re-send the MBMSInterestlndication message after the handover procedure.
  • the target eNB does not support MBMS service continuity. This is the case at points C and F.
  • the target eNB does not add the mbms-InterestlndicationRequest within the mobilityControlInfo IE.
  • the UE does not transmit the
  • MBMSInterestlndication message to the target eNB to save signaling resources.
  • the target eNB supports MBMS service continuity, but belongs to another MBSFN area than the source eNB and broadcasts other MBMS SAIs.
  • scenario E Neighbor information between the neighboring eNBs can be exploited, i.e. if the target eNB knows that it will not be able to support MBMS service continuity to the UE 401 because it belongs to another set of MBMS SAIs, it would add the mbms- InterestlndicationRequest flag and may set the flag to FALSE. Then, the UE 401 would read relevant system information to check whether MBMS SAI #2 provides the same MBMS service as well before sending the MBMSInterestlndication message. Thus, unnecessary control signaling can be avoided.
  • the MBMSInterestlndication message can be forwarded to the target eNB within the HandoverPreparationlnformation message provided from the source eNB to the target eNB via X2/S1 as highlighted below.
  • the HandoverPreparationlnformation message can be considered by the target eNB, provided that it supports the
  • MBMSInterestlndication message to set the mbms-InterestlndicationRequest flag appropriately.
  • the MBMSInterestlndication message can only be included in the X2/S1
  • HandoverPreparation message if the source eNB supports the MBMSInterestlndication message. If the MBMSInterestlndication message is included, the target eNB sets the mbms-InterestlndicationRequest flag to FALSE to avoid unnecessary and redundant transmission of the MBMSInterestlndication message. Otherwise, if the
  • MBMSInterestlndication message is not forwarded to the target eNB via X2/S 1 , the target eNB could blindly set the mbms-InterestlndicationRequest flag to TRUE in order to avoid any delays.
  • the HandoverPreparationlnformation message is used to transfer the E-UTRA RRC information which is used by the target eNB during handover preparation.
  • the message send in a direction from a source eNB or a source RAN to a target eNB.
  • HandoverPreparationlnformation data structure is defined in 3GPP TS 36.331. Within this data structure a new Rel-1 1 IE, e.g. "MBMSInterestlndication" can be included in the ASN.l code as follows:
  • HandoverPreparationInformation-v920-IEs SEQUENCE ⁇
  • HandoverPreparationInformation-vllxy-IEs SEQUENCE ⁇ mbmslnterestlndication-rll B SInterestlndication-rll OPTIONAL,
  • the suffix "r-1 1" indicates to Re 1-11.
  • the MBMSInterestlndication message contains the MBMS frequencies on which the UE is interested or is receiving MBMS services.
  • the MBMSInterestlndication message may be forwarded to the target eNB in the same format as the UE sends it to the serving cell.
  • the target eNB can consider the MBMS frequencies to avoid unwanted inter-frequency handovers and reconfigurations of the SCells that would result in MBMS service interruption.
  • the concepts as explained show the following advantages. Signaling via the radio interface is reduced. If the target eNB does not support MBMS service continuity, e.g. because it only supports pre-Rel-11 MBMS features or because it is not geographically located within an MBMS Service Area or does not overlap with any MBMS Service Area, the mbms-interestlndicationRequest flag is set to FALSE to avoids unnecessary signaling specifically in the uplink, but also downlink control signaling to send uplink grants to the UE.
  • Delay is reduced after the handover procedure. If the target eNB supports MBMS service continuity and sets the (mbms-interestlndicationRequest) flag set to TRUE, the UE can send the MBMS interest indication message to the target eNB immediately after successful handover procedure. Thus, the UE does not lose any time by reading relevant system information to find out that the target eNB supports the MBMS interest indication message.
  • the immediate transmission of the UE's MBMS interest avoids that MBMS service interruption caused by inter- frequency handovers or service cell reconfiguration due to 'late' reception of the MBMS interest indication message.
  • the UE's MBMS interest is already considerd during the handover procedure.
  • Fig. 5 shows a flow chart for illustrating a method according to an embodiment of the invention.
  • the method supports service continuity in a cellular communication system comprising a source base station, a target base station and a user equipment to be handed over from the source base station to the target base station.
  • the user equipment is moving from a cell served by the source base station to a cell served by the target base station.
  • a cellular communication system generally comprises multiple base stations that are placed at different locations to provide coverage while the user equipment is moving within the cellular network.
  • Each base station spans one or multiple cells, e.g. one per frequency and per sector, which is determined by an antenna direction.
  • the user equipment can change the serving base station, i.e. when the user equipment moves from the coverage area of the serving base station, i.e. the source base station, to the coverage area of another base station, i.e. the target base station.
  • handover procedures are defined to exchange relevant information.
  • Handover procedures may include data forwarding between affected nodes.
  • An example of a service which is provided to the UE is a broadcast service, in particular an MBMS service.
  • the source base station obtains an indication whether the target base station supports a service continuity feature.
  • the indication can be a flag which is - when used - either set to TRUE or to FALSE.
  • the indication can be provided to the source base station by the network, e.g., via an Operation Support Systems (OSS).
  • OSS Operation Support Systems
  • the source base station can also obtain the indication via a message that is sent from the target base station to the source base station.
  • the flag can be inserted in such a message or can also be left out. In the latter case it is indicated that the target base station does not support the service continuity feature, e.g. the target base station is either not capable of supporting the service continuity feature or is not within the service area and can thus not provide service continuity to the user equipment.
  • the indication that a service continuity feature is supported by the target base station may indicate that the target base station is adapted to receive the indication, e.g. from the user equipment, that the user equipment is interested in receiving a certain service.
  • the indication that a service continuity feature is supported may generally indicate that service continuity, such as MBMS service continuity, or a service interest indication message, such as the MBMS interest indication message, is supported.
  • the indication that the target BS supports a service continuity feature may in particular also indicate that the target BS requests an indication from the user equipment (indication that the user equipment is interested in receiving a service).
  • the source base station sends the indication whether the target base station supports the service continuity feature to the user equipment.
  • the source base station may just forward the indication received from the target base station to the user equipment. This may be done in a transparent manner.
  • the indication can be included in a message to be sent from the source base station to the user equipment.
  • the user equipment checks the received indication, such that the user equipment knows whether the target base station supports the service continuity feature or not.
  • the user equipment may also know from the check whether the target base station wants to receive service interest indication from the user equipment or not. For example, if the flag is set to TRUE, the user equipment interprets that the target base station supports the service continuity feature and wants to receive the service interest indication from the user equipment, if the flag is set to FALSE, the user equipment interprets that the target base station supports the service continuity feature, but does not want to receive the service interest indication immediately after the handover procedure, or if the flag is left out, the user equipment interprets that the target base station does not support service continuity, e.g. because it is not within the service area or because it does not support the service continuity feature.
  • the user equipment If the user equipment understands from the received indication that the target base station does not support the service continuity feature, the user equipment will not send the indication that the user equipment is interested in receiving a service. The user equipment does not send this indication as it already knows that the target base station will not understand the indication or cannot provide or assist the user equipment in receiving the service. In this way signaling overhead is reduced.
  • the user equipment sends, to the target base station, an indication that the user equipment is interested in receiving a service (step S54).
  • the user equipment understands from the received indication that sending of the indication is requested, the user equipment also sends to the target base station, an indication that the user equipment is interested in receiving a service.
  • This indication from the user equipment is preferably send as early as possible from the user equipment to the target base station, e.g. right after the handover of the user equipment from the source base station to the target base station, e.g. even before the user equipment receives any system information from the target base station.
  • the delay between the finalized handover and the time instance in which the target base station receives the indication that the user equipment is interested in a service is minimized.
  • the risk that the user equipment is reconfigured by the target base station, without the target base station knowing that the handed over user equipment wants to receive a certain service is reduced. This reduces the risk of interruptions of the service due to any reconfigurations and reduces the delay until the service can be provided.
  • the target base station Once the target base station has received the indication that the user equipment is interested in receiving a service, it will ensure that the service can be continuously received by the user equipment.
  • the indication that the user equipment is interested in receiving a service may comprise at least one frequency on which the service is obtained.
  • the user equipment may also send further parameter of the service within the indication or within another message. Such a parameter can be a priority of a service.
  • the service for which the user equipment indicates its interest may be a broadcast service, in particular an MBMS service.
  • FIG. 6 schematically illustrates different nodes of a cellular communication system 600 according to embodiments of the invention.
  • a source base station 601 supports service continuity in the cellular communication system 600 comprising the source base station 601 , a target base station 611 and a user equipment 621 to be handed over from the source base station 601 to the target base station 600.
  • the source base station 601 comprises a network interface 602 for obtaining an indication whether the target base station 611 supports a service continuity feature.
  • a receiver 604 for communication via an air interface may be adapted for obtaining an indication whether the target base station 611 supports a service continuity feature.
  • the source base station 601 further comprises a transmitter 603 for sending the obtained indication to the user equipment 621.
  • the target base station 611 for supporting service continuity comprises a network interface 613 for sending to the source base station 601 an indication whether the target base station 611 supports a service continuity feature.
  • a transmitter 614 for communicating via an air interface may be adapted for sending to the source base station 601 an indication whether the target base station 611 supports a service continuity feature.
  • the target base station 611 further comprises a receiver 612 for receiving, form the user equipment 621 , an indication that the user equipment 621 is interested in receiving a service.
  • the user equipment 621 for supporting service continuity comprises a receiver 622 for receiving from the source base station 601 an indication whether the target base station 611 supports a service continuity feature and/or whether the target base station wants to receive an interest indication from the user equipment 621 , a processor 624 for checking the received indication and a transmitter 623 for sending, to the target base station 611 , if the target base station 611 supports the service continuity feature and/or wants to receive an interest indication from the user equipment 621 , an indication that the user equipment 621 is interested in receiving a service.
  • Figure 7 shows a flow chart for illustrating a method according to an embodiment of the invention.
  • the method can be advantageously combined with the methods and concepts described with respect to Figure 5.
  • the method supports service continuity in a cellular communication system comprising a source base station, a target base station and a user equipment to be handed over from the source base station to the target base station.
  • the target base station receives from the source base station an indication that the user equipment is interested in receiving a service.
  • the source base station may receive this indication from the user equipment and forward the indication to the target base station.
  • the source base station may receive the indication from a previous source base station.
  • the service may be an MBMS service.
  • the indication may be send via an MBMS interest indication message.
  • the target base station checks the received indication and indicates whether the target base station wants the user equipment to send the indication that the user equipment is interested in a service to the target base station (after handover).
  • the target base station may not want to receive the indication again from the user equipment after the user equipment is handed over from the source to the target base station in order to avoid unnecessary signaling via the radio interface.
  • the indication whether the target base station wants the user equipment to send the indication that the user equipment is interested in receiving the service to the target base station may be sent from the target base station to the source base station.
  • the source base station may then send the indication received from the target base station to the user equipment, the user equipment may then check the received indication and - depending on the received indication - either send the indication that the user equipment is interested in receiving a service to the target base station (after handover) or not;
  • Fig 8 schematically illustrates a base station 801 for implementing above described concepts and for supporting service continuity in a cellular communication system.
  • the communication system may comprising a source base station, the base station 801 and a user equipment to be handed over from the source base station to the base station 801.
  • the base station 801 comprises a network interface 803 for receiving, from the source base station, an indication that the user equipment is interested in receiving a service.
  • a receiver for communicating via an air interface is adapted to receive an indication that the user equipment is interested in receiving a service.
  • the base station 801 further comprises a processor 802 for checking the received indication and indicating whether the base station requests the user equipment to send the indication that the user equipment is interested in receiving the service to the base station 801 (after handover).
  • Fig. 9 schematically illustrates exemplary structures for implementing the above - described concepts in the base station 901.
  • the base station may act as a source base station or a target base station during a handover of a user equipment.
  • the base station 901 includes a radio interface 902 for communicating with one or more user equipments served by the base station 901 and optionally for communicating with another base station.
  • the radio interface 902 includes one or more transmitters 906, and that for implementing receiver functionalities (RX) functionalities the radio interface 902 may include one or more receivers 907.
  • the base station 901 includes a processor 903 coupled to the interface 903 and a memory 904 coupled to the processor 903.
  • the memory 904 may include a ROM, e.g., a flash ROM, a RAM, e.g., a DRAM or SRAM, a mass storage, e.g., a hard disk or solid state disk, or the like.
  • the memory 904 includes suitably configured program code to be executed by the processor 903 so as to implement the above-described functionalities of the base station 901. More specifically, the memory 904 may include a configuration module 905 for accomplishing the above-described indicating whether the user equipment is requested to send the indication that the user equipment is interested in receiving a service.
  • the structure as illustrated in Fig. 9 is merely schematic and that the base station 901 may actually include further components which, for the sake of clarity, have not been illustrated, e.g., further interfaces or additional processors.
  • the memory 904 may include further types of program code modules, which have not been illustrated.
  • the memory 260 may include program code modules for implementing typical functionalities of a base station, e.g., as described in the 3GPP LTE specifications.
  • a computer program product may be provided for implementing concepts according to embodiments of the invention, e.g., a computer-readable medium storing the program code and/or other data to be stored in the memory 904.
  • Fig. 10 shows a flow chart for illustrating a method in a user equipment according to an embodiment of the invention.
  • the illustrated method concerns concepts that have been described above, such as the concepts discussed with respect to Fig. 7, and describes these concepts from a perspective of the user equipment.
  • the method in a user equipment supports service continuity in a cellular communication system, which comprising a source base station, a target base station and the user equipment moving from the source base station to the target base station.
  • step S 101 an indication of the target base station is received whether the target base station requests the user equipment to send the indication that the user equipment is interested in receiving a service to the target base station.
  • step SI 02 it is determined, on the basis of the received indication, whether to send the indication that the user equipment is interested in receiving a service to the target base station.
  • the interest indication may be sent to the target base station via the air interface between the user and the target base station.
  • Fig. 1 1 schematically illustrates exemplary structures for implementing the above- described concepts in the user equipment 1101.
  • the user equipment may be handed over from a source to a target base station.
  • the user equipment 1 101 includes a radio interface 1 102 for performing data transmission to or from a mobile network, e.g., via the base station 901.
  • the radio interface 1102 may be configured for receiving an indication of the target base station whether the user equipment 1 101 is requested to send the interest indication for a service to the target base station.
  • the radio interface may further be configured to send the interest indication from the user equipment to the target base station.
  • TX transmitter
  • RX receiver functionalities
  • the radio interface 1102 may include one or more receivers 1104.
  • the radio interface 1102 may correspond to the LTE-Uu interface.
  • the UE 1 101 includes a processor 1 105 coupled to the radio interface 1 102 and a memory 1 106 coupled to the processor 1105.
  • the memory 1 106 may include a ROM, e.g., a flash ROM, a RAM, e.g., a DRAM or SRAM, a mass storage, e.g., a hard disk or solid state disk, or the like.
  • the memory 1006 includes suitably configured program code to be executed by the processor 1005 so as to implement the above-described
  • the memory 1 106 may include a control module 1108 for determining whether to send the indication that the user equipment is interested in receiving a service to the target base station.
  • the structure as illustrated in Fig. 1 1 is merely schematic and that the user equipment 1 101 may actually include further components which, for the sake of clarity, have not been illustrated, e.g., further interfaces or additional processors.
  • the memory 1 106 may include further types of program code modules, which have not been illustrated.
  • the memory 1 106 may include program code modules for implementing typical functionalities of a user equipment or program code of one or more applications to be executed by the processor 1105.
  • a computer program product may be provided for implementing concepts according to embodiments of the invention, e.g., a computer-readable medium storing the program code and/or other data to be stored in the memory 1 106.
  • the concepts as explained above allow reducing signalling overhead.
  • the interest indication from the user equipment to the target base station is only send in case the UE receives an indication to do so.
  • the concepts allow for improved service continuity for a user equipment in handover situations.
  • the interest indication can be used at the target base station to avoid inter frequency handovers and reconfigurations of the serving cell which potentially interrupts the service continuity. Further the interest indication is available at the base station early such that interruptions of the service continuity are avoided.
  • Embodiment for supporting service continuity in a cellular communication system comprising a source base station, a target base station and a user equipment to be handed over from the source base station to the target base station, the method comprising the steps: the source base station obtaining an indication whether the target base station supports a service continuity feature; the source base station sending the obtained indication to the user equipment; and the user equipment checking the received indication and, if the target base station supports the service continuity feature, the user equipment sending, to the target base station, an indication that the user equipment is interested in receiving a service.
  • Embodiment according to 1 or 2 wherein the user equipment sending to the target base station at least one parameter of the service.
  • Embodiment in a source base station for supporting service continuity in a cellular communication system comprising the source base station, a target base station and a user equipment to be handed over from the source base station to the target base station, the method comprising the steps: obtaining an indication whether the target base station supports a service continuity feature; and sending the obtained indication to the user equipment.
  • Embodiment in a target base station for supporting service continuity in a cellular communication system comprising a source base station, the target base station and a user equipment to be handed over from the source base station to the target base station, the method comprising the steps: providing the source base station with an indication whether the target base station supports a service continuity feature; and receiving form the user equipment an indication that the user equipment is interested in receiving a service.
  • Embodiment in a user equipment for supporting service continuity in a cellular communication system comprising a source base station, the target base station and a user equipment to be handed over from the source base station to the target base station, the method comprising the steps: receiving from the source base station an indication whether the target base station supports a service continuity feature; and checking the received indication and, if the target base station supports the service continuity feature, the user equipment sending, to the target base station, an indication that the user equipment is interested in receiving a service.
  • Embodiment involving a base station for supporting service continuity in a cellular communication system comprising the base station, a target base station and a user equipment to be handed over from the base station to the target base station, the base station comprising: a receiver for obtaining an indication whether the target base station supports a service continuity feature; and a transmitter for sending the obtained indication to the user equipment.
  • Embodiment involving a base station for supporting service continuity in a cellular communication system comprising a source base station, the base station and a user equipment to be handed over from the source base station to the base station, the base station comprising: a transmitter for sending to the source base station an indication whether the base station supports a service continuity feature; and a receiver for receiving, form the user equipment, an indication that the user equipment is interested in receiving a service.
  • Embodiment involving a user equipment for supporting service continuity in a cellular communication system comprising a source base station, a target base station and a user equipment to be handed over from the source base station to the target base station, the user equipment comprising: a receiver for receiving from the source base station an indication whether the target base station supports a service continuity feature; and
  • a processor for checking the received indication and, a transmitter for sending, to the target base station, if the target base station supports the service continuity feature, an indication that the user equipment is interested in receiving a service.

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

Abstract

L'invention concerne des méthodes et des nœuds dans un système de communication cellulaire pour prendre en charge la continuité de service dans des situations de transfert. L'invention concerne également une méthode par laquelle un système de communication cellulaire comprend une station de base source, une station de base cible et un équipement d'utilisateur déplacer de la station de base source à la station de base cible. La méthode comprend les étapes suivantes : la station de base cible reçoit, en provenance de la station de base source, une indication que l'équipement d'utilisateur est intéressé à recevoir un service ; la station de base cible vérifie l'indication reçue et la station de base cible, indique si la station de base cible demande à l'équipement d'utilisateur d'envoyer l'indication que l'équipement utilisateur est intéressé à recevoir un service de la station de base cible.
PCT/EP2013/055672 2012-03-19 2013-03-19 Continuité de service dans des situations de transfert dans des systèmes de communication cellulaire WO2013139778A1 (fr)

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US201261612723P 2012-03-19 2012-03-19
US61/612,723 2012-03-19

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CN114765820A (zh) * 2021-01-15 2022-07-19 中国移动通信有限公司研究院 多播业务的信息交互方法及基站
WO2022152257A1 (fr) * 2021-01-15 2022-07-21 中国移动通信有限公司研究院 Procédé d'échange d'informations pour service de multidiffusion et station de base

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