Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W36/00—Hand-off or reselection arrangements
  • H04W36/14—Reselecting a network or an air interface
• • 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
  • H04W36/302—Reselection being triggered by specific parameters by measured or perceived connection quality data due to low signal strength
• • 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
  • H04W48/00—Access restriction; Network selection; Access point selection
  • H04W48/20—Selecting an access point
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W72/00—Local resource management
  • H04W72/04—Wireless resource allocation
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04W—WIRELESS COMMUNICATION NETWORKS
  • H04W76/00—Connection management
  • H04W76/10—Connection setup
• • 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
  • H04W88/08—Access point devices
• • 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
  • H04W88/12—Access point controller devices

Definitions

• the present invention relates to the control of radio resources allocated to a mobile terminal in communication in a cellular system, and more particularly to procedures for transferring links between cells.
• Such a transfer is commonly called intercellular "handover".
• HHO rigid handover
• SHO soft handover
• HHO rigid handover
• SHO soft handover
• the second generation GSM Global System for Mobile Communications
• TDMA time-division multiple access
• the third generation UMTS system (“Universal Mobile Telecommunication System”) uses a wideband code division multiple access technique (W-CDMA, “Wideband Code-Division Multiple Access”), which allows it to support HHO and SHO.
• W-CDMA Wideband Code-Division Multiple Access
• the handover procedures are executed in cellular systems, in an automatic manner in general, so as to provide the mobile in connected mode, that is to say having a call in progress, a radio link quality sufficiently good for the communication can be continued under favorable conditions.
• Other handover criteria also exist, based on considerations not directly related to the propagation conditions, such as the distribution of traffic according to the type of cells.
• a handover procedure includes a measurement step, in which at least one mobile station and one base station regularly carry out radio measurements relating to propagation conditions, downlink (measurements at the mobile receiver) or uplink (measurements at the level of the receiver of one or more base stations on signals from the mobile). If a communication channel is established between the mobile station and a base station, measurements can be made on this channel. These measurements reflect in particular the level of signal rising and falling on the radio channel. They can also take into account an indicator of the quality of the radio link as well as an indicator of the distance separating the mobile station from the base station. In addition, the mobile station regularly performs measurements on the strongest signals it receives from a number of neighboring cells. In the other direction, the base stations of these neighboring cells can also carry out measurements on the uplink signal.
• this system entity which manages the handover procedure is a base station controller (BSC), or radio network controller (RNC).
• BSC base station controller
• RNC radio network controller
• the list of neighboring cells to be taken into consideration is determined by the controller, and the receivers concerned are controlled accordingly.
• the references of the cells concerned are broadcast on a common control channel and / or transmitted to the mobile terminal on a dedicated resource.
• the controller activates the measurements at the base station receivers.
• a transfer is then decided by the controller who is responsible for determining, according to the previous criterion, the cell - called target - most suitable for receiving the mobile station and the communication in progress (or in the case of the SHO, that which will be added to the active set of base stations having a communication channel with the terminal).
• the radio network controller also has other information, which it can take into account in its algorithms, in particular the choice of target cell.
• the instantaneous charge of a neighboring candidate cell for example can thus be part of the elements to be taken into account in the final choice of the target cell, in addition to criteria related to the estimated quality of the new radio link.
• HHO the changeover is made.
• the new cell is added to the active set and the current cell can be removed later from the active set.
• PLMN radiocommunication networks
• zone B ' This allows B subscribers to benefit from more extensive coverage than zone B '. In return, there is normally a fee paid by B to A. However, in zone B ', operator B generally wants subscribers' communications to use its own infrastructure, in order to make it profitable and avoid payments to A.
• the “network” or PLMN of this virtual operator can be seen as consisting of its subscriber management bodies (HLR, “Home Location Register”) associated with the switching and radio access resources borrowed from a other operator.
• HLR subscriber management bodies
• PLMN identities are taken into account by the mobiles in the process of cell selection and reselection, so that the referral is made in a natural way (see technical specifications 3GPP TS 25.304 "UE Procedures in Idle Mode and Procedures for Cell Reselection in Connected Mode", version 3.8.0 Release 1999, published in September 2001 by the 3GPP and 3GPP TS organization 23.122 "Non-Access-Stratum functions related to Mobile Station (MS) in idle mode", version 4.1.0 Release 4, published in June 2001 by the 3GPP organization).
• MS Mobile Station
• US Patent 5,561,845 takes advantage of this specificity of the standby mode and proposes a method for promoting, for a mobile subscriber, the use of its home network when it wishes to establish a call.
• a device (“border protector”), not offering the dedicated communication resources of a base station, repeats control signals transmitted by two PLMNs, in an intermediate zone corresponding to the overlap between two zones respectively served by the two PLMNs. These retransmitted control signals are designed to be the strongest signals in the intermediate zone.
• the mobiles in standby mode in the intermediate zone select the channels broadcast in this zone and are redirected to their home PLMN by the "border protector" during a call establishment request, based on an identifier of the mobile.
• nothing is planned for active mobiles.
• a subscriber terminal of B in communication with a base station of the shared zone C and heading towards the zone B ', currently has no means of having its communication transferred as a priority or systematically to a station basic operator B, in particular because it is not the mobile that controls the handover procedures.
• the invention thus provides a method for controlling radio resources allocated to a mobile terminal in communication in a cellular system, in which radio measurements are obtained relating to propagation conditions between the terminal and a group of base stations of the cellular system . These measurements are analyzed to select at least one base station and establish a radio link between the terminal and the selected base station in order to continue the communication.
• the cellular system includes a first set of base stations providing radio access resources for subscriber terminals to a first network and a second set of base stations providing radio access resources for subscriber terminals to a first network a second network, the first and second sets having in common a subset of shared base stations.
• a system radio network controller When the terminal in communication has an active radio link with a shared base station of said subset, a system radio network controller cellular stores information identifying a home network of said terminal and the selection of another base station not belonging to said subset is made dependent on the stored information identifying the home network of the terminal.
• Each mobile having a connecting PLMN the identification of this one is thus taken into account in the handover procedure executed by the controller in charge of the shared area. This gives operators great flexibility in defining how to orient the handovers of their respective subscribers outside the shared area. The same flexibility is offered for subscribers of other operators, who are roaming.
• the information identifying the terminal's home network can be deduced by the system from the identity of the mobile subscriber using ie terminal, which saves the system from having to manage an additional parameter.
• the invention also provides a radio network controller suitable for implementing the above method.
• the single figure is a block diagram of an embodiment of the invention in a UMTS (“Universal Mobile”) radio network.
• UMTS Universal Mobile
• the Telecommunications System in circuit transmission mode.
• the invention is described below in its application to a UMTS network for voice transmission in circuit mode.
• This application is illustrated by the single figure.
• the single figure shows a UMTS 5 core network, comprising at least one MSC (“Mobile services Switching Center”) switch and at least one HLR (“Home Location Register”) subscriber management system.
• MSC Mobile services Switching Center
• HLR Home Location Register
• This equipment is operated by at least one operator.
• each HLR deployed in this core network corresponds to a PLMN and to a set of subscribers of the operator of this PLMN.
• the operator of PLMN A manages the HLR 8A
• the operator of PLMN B manages the HLR 8B.
• Radio Access Network Subsystem comprising at least one radio network controller 40-43 or RNC ("Radio Network Controller"), which manages a set of base stations 2-4, or "Node-B", each comprising at least one transceiver.
• RNC Radio Network Controller
• Node-B Radio Network Controller
• the base stations 2-3 controlled by the RNC 40 to 42 define the coverage area 21 of the PLMN A
• the base stations controlled by the RNC 43 define the coverage area of PLMN B
• the base stations controlled by RNC 43 having in this example approximately the same coverage area 31 as those controlled by RNC 42.
• This area 31 is called “strategic area”, while the area covered by the base stations controlled by RNC 40 and 41 is the "shared area”.
• COMMON ID At the establishment of. communication between a terminal 1 and a base station 2 in the shared area, a procedure called COMMON ID is performed. This procedure is described in the technical specification 3GPP 25.413 ("UTRAN lu Interface RANAP Signaling", version 4.1.0 Release 4, published in June 2001 by the 3GPP organization). It consists, for the core network 5 on which communication depends, of providing the RNC 41 under the control of which the terminal 1 is located, the international identity of the mobile subscriber (IMSI, “International Mobile Subscriber Identity”) of this terminal .
• IMSI International Mobile Subscriber Identity
• RNC Radio Resource Control
• RRC Radio Resource Control
• a unique IMSI parameter is in fact assigned to each mobile subscriber and stored in the HLR of its home network.
• the 3GPP 23.003 standard (“Numbering, Addressing and Identification”, version 4.1.0 Release 4, published in June 2001 by the 3GPP organization) details the structure of this parameter. This is made up of 15 bits. Starting with the most significant bits:
• the MCC Mobile Country Code
• the MCC uniquely identifies the country of the mobile subscriber's home network
• the next two or three bits constitute the MNC ("Mobile Network Code”). Its length depends on the MCC.
• the MNC gives an indication of the home network of the mobile subscriber
• MSIN Mobile Subscriber Identification Number
• the RNC which has this information, can deduce in a certain and unique manner, from the first fields MCC and MNC of the IMSI, the home network of the mobile subscriber associated with the terminal 1.
• the RNC uses this information from the IMSI to filter the neighboring cells, the frequencies and scrambling codes of which it communicates to the terminal on a communication channel of the base station supporting communication in Classes.
• terminal 1 having as its home network PLMN A (that is to say the one whose subscribers are listed in HLR 8A), is in the course of communication with a base station 2 under the responsibility of RNC 41 and that cells neighboring PLMN A and B have already been defined for this base station, RNC 41 can instruct the terminal to make signal level measurements only on cells neighboring PLMN A.
• PLMN A that is to say the one whose subscribers are listed in HLR 8A
• this operation is possible by sending, in the "Measurement control" message from RNC 41 to terminal 1 on a dedicated DCCH signaling radio channel "Dedicated Control Channel") and scrambling codes on which the terminal must measure, as described in sections 8.4.1 and 10.2.17 of the technical specification 3GPP TS 25.331, "RRC Protocol Specification”, version 4.1.0 Release 4, published in June 2001 by gold 3GPP organization.
• the terminal 1 will only make its measurement reports to the RNC 41, via the current base station 2, only for the corresponding cells.
• the uplink measurements may only be carried out and reported by the base stations managing neighboring cells of the PLMN On request of the RNC. This case follows the procedures described in the technical specification 3GPP TS 25.433 "UTRAN lub Interface NBAP Signaling", version 4.2.0 Release 4, published by the 3GPP organization in September 2001 (sections 8.3.8 to 8.3.11 and 9.1 .52 at 9.1.57).
• the RNC After analyzing the measurement reports received, the RNC will activate a radio link with the terminal only for a PLMN A cell and not for a PLMN B cell for which no measurement is available due to prior filtering based on the PLMN identity.
• the creation of this radio link can be done in SHO, by notifying the mobile of the update of its active set (section 8.3.4 of the above-mentioned specification 3GPP TS 25.331) and by activating the resource of the base station 3 concerned ( section 8.3.17 of the aforementioned 3GPP TS 25.433 specification), or in HHO (sections 8.3.5. and ⁇ .2.17 ⁇ respectively of the 3GPP TS 25.331 and 3GPP TS 25.433 specifications).
• terminal 1 in communication in the shared area, is attached to PLMN B, the same process of prior filtering of the cells makes it possible to eliminate the cells of PLMN A covering strategic area 31, that is to say those controlled by RNC 42.
• the handover from the shared area to the strategic area will generally be an HHO.
• a second embodiment consists for the RNC 41 in providing the terminal 1, in communication with a base station 2 of the shared area, the scrambling codes corresponding to the neighboring cells previously declared for the base station, regardless of whether those - these are associated with PLMN A or PLMN B base stations.
• the terminal performs measurements on the codes of all neighboring cells and sends its measurement reports to the RNC, according to the same procedure as that described above.
• the RNC classifies the neighboring candidate cells to establish a communication link with the terminal and continue communication. It can at this stage take into account the PLMN identity deduced from the terminal IMSI, initially retrieved in the COMMON ID procedure, in comparison with the PLMNs on which the neighboring cells thus classified depend.
• the operator may favor base stations 3 depending on its RNC 42 and only use those 4 depending on RNC 43 of PLMN B only in the event of a more serious risk of loss communication, or in the event of saturation of the resources of the target cells dependent on the RNC 42.
• Symmetrical operation can be provided for PLMN B subscribers. It can also be provided that PLMN A base stations 3 in strategic area 31 can provide them with SHO links in addition to those provided by shared base stations 2 near strategic zone 31, in order to improve transmission conditions.
• the identity of PLMN in the handover procedure can also be useful in cases where the home network of terminal 1 does not correspond to PLMN A or PLMN B, but to a third PLMN, for example a foreign PLMN in the case of "roaming".
• the algorithm for choosing the target cell carried out by the RNC 41 can favor the PLMN A on which the communication started, or else the PLMN B. It can still distribute the traffic between the two PLMN A and B according to multiple criteria , which can be linked to the load on the cells of the first access network or any other parameter.
• the identity of PLMN gives operators great flexibility in this regard to make the roaming agreements that suit them.
• the invention is not limited to the embodiment described above by way of example. It also extends to other variants.
• the two access networks of the PLMNs A and B described above can be attached for example to the same MSC or else to very distinct core networks.

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

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• 2001
  • 2001-10-29 FR FR0113964A patent/FR2831762B1/fr not_active Expired - Fee Related
• 2002
  • 2002-10-17 WO PCT/FR2002/003556 patent/WO2003039184A1/fr not_active Ceased
  • 2002-10-17 EP EP02802319A patent/EP1446977A1/de not_active Withdrawn
  • 2002-10-17 US US10/493,997 patent/US20040242260A1/en not_active Abandoned

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