FR2790633A1 - Mobile radio communications cellular system additional resource access technique having attempted access and authorised user identification accessing resources outside preferred zone. - Google Patents

Abstract

The additional resources access method has a step of detecting an access attempt (1). The user is identified as an authorised user (2). The user is detected as being in the preferred zone (3). Following detection access is carried out or inter cell transfer is carried out again and a transfer made to the resources outside the preferred zone (4).

Description

METHOD FOR INTERCELLULAR ACCESS OR TRANSFER IN A

  CELLULAR MOBILE RADIO COMMUNICATION SYSTEM

  The present invention relates generally to cellular mobile radiocommunication systems, i.e. cellular mobile radiocommunication networks and mobile stations intended for use in

these networks.

  It is known in cellular mobile radio systems to distinguish two operating modes for mobile stations: - the dedicated mode, in which a mobile station has at its disposal one or more dedicated channels (be it traffic channels, used to transmit traffic information, or signaling channels, used to transmit signaling information, either during a call or outside a call), - standby mode, in which a mobile station does not have dedicated channels at its disposal, but must nevertheless remain in contact with the network, which it does

  through channels called common channels.

  In known manner, each cell is associated with a particular frequency called beacon frequency, on which said common channels are broadcast, and the process of selection (or reselection) of serving cell by a mobile station

is briefly the following.

  In standby mode, the mobile station receives on the beacon frequency of its waiter cell first system information constituted by a list of beacon frequencies associated with neighboring cells of its waiter cell. The mobile station then successively searches for each of these beacon frequencies, in order on the one hand to carry out radio measurements thereon, and on the other hand to acquire, after synchronization, second system information constituted by a certain number of parameters making it possible, by combination with said radio measurement results, to determine whether a selection criterion is verified for this beacon frequency, then, by comparison to the results obtained in the same way for the other beacon frequencies, to determine the cell to be selected. The mobile station then determines, by means of third system information broadcast on the beacon frequency of the cell to be selected, whether or not this cell belongs to the same location area as the current serving cell. If so, the cell to be reselected becomes the new waiter cell. Otherwise, the mobile station notifies the network beforehand, via a location update procedure, in order to have the network verify the user's right to access the cell thus determined. In the case of a positive response from the network, this cell

  becomes the new waitress cell.

  In addition, when a mobile station is put into service, no waiter cell having yet been selected, the mobile station selects a waiter cell according to the same principles, but by exploring all of the beacon frequencies, and using a so-called registration procedure for checking access rights to

the selected cell.

  In addition, according to a so-called "directed retry" function (translated here by "re-oriented re-test"), in the event that a call cannot be established in a cell thus selected in standby mode (in particular for for traffic reasons, because of traffic overload in this cell, or for radio reasons, because of radio propagation problems in this cell) the network instructs the mobile station to retry access to the network in cells indicated to him

  in the call establishment phase.

  The procedure by which a mobile station switches from standby to sleep mode

  dedicated is also called access procedure.

  In dedicated mode, a similar cell selection process is implemented, except that the mobile station reports measurement results to the network, and the network determines, on this basis as well as on the basis of other parameters, the target cell to select, that is to which an inter-cellular transfer, or more simply transfer (or "handover" in English), is to be performed. More precisely, the selected cell is the first of the cells transferred (classified in a certain order, according to the measurement results) to which the network determines that a transfer is possible, that is to say in particular in which resources are available for such transfer. Similarly, a so-called "directed retry" function can be performed, in the case where a transfer cannot be made to the cells thus tested (in particular for traffic reasons, due to traffic overload in these cells, or for radio reasons,

  because of radio propagation problems in these cells).

  For a more complete description of the cellular systems of

  mobile radiocommunications such as the GSM system ("Global System for Mobile communications") it is possible to refer to the book by M. Mouly and M.B. Pautet,

  entitled "The GSM System for Mobile Communications" (Palaiseau, France, ISBN: 2-

9507 190-07-7).

  The present invention relates more particularly to a cellular mobile radio communication system in which additional services are offered to so-called authorized users in cells known as preferred cells forming an area known as a preferred area. Depending on whether the rights of these users are limited or not to this preferred area, these preferred cells can either be

  more preferred cells, that is, exclusively authorized cells.

  In such a system, there is the possibility, for authorized users, that an inter-cellular access or transfer to preferred cells fails, in particular for traffic reasons (due to an overload of traffic in these cells ), or for radio reasons (due to radio propagation problems in these cells). This can therefore cause call interruptions, which

  will then be very badly perceived by authorized users.

  The present invention aims in particular to provide a solution to this problem. Document WO 96/34499 describes a system in which so-called fixed subscribers have access rights limited to certain cells forming a so-called fixed subscription area. This document describes a so-called "re-direction" function, according to which if a cell other than those of a fixed subscription area is selected in standby mode, and if at least one cell of this fixed subscription area is a cell close to the selected cell, then the network indicates these neighboring cells to the mobile station, so that the mobile station can select one of these neighboring cells for the establishment of a call. However, this document does not deal with

  not from the previously mentioned problem.

  Document WO 9838827 describes a system comprising cells known as special cells in which special services are available for certain users. In this document, a list of cells known as a special list is composed for a mobile station and transmitted to a base station controller during the establishment of a call, and if necessary during an inter-cellular transfer, so as to redirect a mobile station to such a special cell if necessary. This

  The document also does not address the problem mentioned above.

  The subject of the present invention is a method of access or inter-transfer

  cell in a mobile radiocommunication system in which additional services are offered to so-called authorized users in cells known as preferred cells forming a zone known as preferred zone, said method being essentially characterized in that it comprises the following steps detection that an inter-cellular access or transfer attempt to preferred cells has failed, detection that the user is an authorized user, detection that the user is in the preferred zone,

  following such detections, implementation of a retest function

  oriented, for inter-cellular access or transfer to a cell outside of this

preferred area.

  According to another characteristic, said cell outside of said preferred zone, towards which said re-oriented retest function is performed, is

  selected using results of measurements made by the mobile station.

  According to another characteristic, said measurements are carried out by the mobile station on cells which are indicated to it by the network in a communication channel.

dedicated signage.

  According to another characteristic, said cells indicated to the mobile station by the network are determined in the network from information including the configuration of the cells of the network and an indication of the location of the

mobile station.

  According to another characteristic, said indication of location of the mobile station is determined in the network on the basis of measurement results.

  reported to the network by the mobile station.

  According to another characteristic, it is expected that, following the implementation of said re-oriented retest function, the charging for said authorized user is

  performed as if this user were in said preferred area.

  According to another characteristic, monitoring is carried out, following the implementation of said re-oriented retest function, in order to redirect the station

  mobile to a preferred cell as soon as possible.

  According to another characteristic, said surveillance includes surveillance

  of the traffic load in the preferred area.

  The present invention also relates to a mobile station for the

implementation of such a process.

  The present invention also relates to a network entity of

  mobile radiocommunications for the implementation of such a method.

  Other objects and characteristics of the present invention will become apparent on

  reading of the following description of an exemplary embodiment, made in relation to

  the accompanying drawings in which: FIG. 1 is a diagram intended to illustrate an example of a system to which the present invention is applicable, FIG. 2 is a diagram intended to illustrate an example of access or inter-cellular transfer method according to the invention, FIG. 3 is a diagram intended to illustrate the type of means to be provided in a mobile station for the implementation of a method according to the invention, FIG. 4 is a diagram intended to illustrate the type of means to be provided in a mobile radiocommunication network entity for the implementation of a method according to the invention. A cellular mobile radio communication system essentially comprises, as illustrated in FIG. 1: - a set of base stations (or BTS, for "Base Transceiver Station", such as those noted BTS0, BTS1, BTS2, BTS3 and BTS4 , each of these base stations being, in the example illustrated, assigned to a cell (denoted respectively CO, C1, C2, C3, and C4), and these base stations being in relation, via a radio interface, with mobile stations, such as MS0, MS1, MS2, MS3, MS4, - a set of base station controllers (or BSC, for "Base Station Controller"), such as those denoted BSC1 and BSC2, each of these BSCs controlling, from the point of view of radio resource management, a subset of cells, the base station controller BSC1 controlling in the example illustrated the cells CO, C1 and C2, and the base station controller BSC2 controlling in this example cells C3 and C4, - a set of cen very mobile switching, also called MSC (for "Mobile Switching Center" 'in English), only one of which is illustrated in the figure, each

  of these MSCs controlling, from a communications management point of view, a

  set of base station controllers, re mobile switching center MSC1 controlling in the illustrated example the base station controllers BSC1 and BSC2, - databases such as HLR (for "Home Location Register") or VLR (for "Visitors Location Register"), not specifically illustrated, with which the MSCs are in contact, and in particular making it possible to manage the data

  subscription and user mobility.

  The set formed by BTS and BSC is also called BSS (for "Base

Subsystem station "in English).

  The assembly formed by the MSC, HLR and VLR is also called NSS (for "Network and Switching Subsystem") The various MSCs are also, in a manner not specifically illustrated, in relation to external networks such as in particular the networks PSTN (for "Public Switched Telephone Network") or ISDN (for "Integrated

Digital Network Services ").

  By way of example to which the present invention is applicable, cells such as CO, Cl, and C2 could constitute conventional cells, corresponding for example to GSM cells, and cells such as C3 and C4 could constitute cells in which new services are offered to authorized users, these cells then constituting preferred cells for these

authorized users.

  FIG. 2 is a diagram intended to illustrate an example of a process

  access or inter-cellular transfer according to the invention.

  A failure during an access or handover attempt from a mobile station such as for example MS3, to preferred cells such as C3 and C4 in this example, is detected in step 1 of this figure. Such a failure could, for example, be due to traffic reasons (due to an overload of traffic in the preferred area, in this example comprising cells C3 and C4) or to reasons

  radio (due to radio propagation problems in this preferred area).

  Following such a detection, it is detected in step 2 if the user is a

  authorized user, and in step 3 if this authorized user is in the preferred zone.

  Following such detections, a re-oriented retest function is performed in step 4 for an access or an inter-cellular transfer from the mobile station such as MS3 for example to cells such as CO, Cl, C2 in this example, in

outside of said preferred area.

  In step 5 it can be assumed that access or handover is

  successfully performed to one such cell outside the preferred area.

  Such a cell outside the preferred area, to which such a re-oriented retest function is performed, can be selected using

  results of measurements made by the mobile station.

  Such measurements can be carried out on cells indicated in the

  mobile station via the network in a dedicated signaling channel.

  Such cells indicated to the mobile station by the network can be determined in the network from the configuration of network cells and a

  indication on the location of the mobile station.

  Such an indication of the location of the mobile station can be determined in the network on the basis of measurement results reported to the network by the mobile station. In addition, advantageously, it can be provided that, following the implementation of such a re-oriented retest function, the user is charged as

  if he was in the preferred area.

  Furthermore, advantageously, monitoring can be carried out, following the implementation of such a re-oriented retest function, in order to redirect the station

  mobile to a preferred cell as soon as possible.

  In particular, such monitoring may include monitoring the traffic load in the preferred area. Such monitoring is indicated in step 6, and such re-direction to

  a preferred cell is indicated in step 7.

  FIG. 3 is a diagram intended to illustrate the type of means to be provided

  in a mobile station, in a system according to the invention.

  -As recalled in Figure 3, in a known manner, a mobile station comprises means 10 called air interface, allowing: - firstly to put information from man-machine interface means 11, in a form admissible for their transmission on the air-interface, on the other hand to restore information received on the air-interface, for

  transmission to said man-machine interface means 11.

  The air-interface means 10 themselves comprise, in known manner, transmission-reception means 12, including band processing functions

  base and radioelectric foundations, and control means 13.

  Said control means 13 make it possible in particular to transmit and receive the various signaling messages exchanged between mobile station and network, in the various procedures, or protocols, provided for operation.

in this network.

  In particular, in the inter-cellular access or transfer method considered here, said control means 13 may include means for exchanging signaling information with the network, so as to set up

  operates said re-oriented retest function.

  Said signaling information exchange can use such or such type of

  procedure or protocol already provided for in this type of system.

  Since such procedures are well known to those skilled in the art, and the particular implementation of such means also presenting no particular difficulty for those skilled in the art, such means need not be described

  here in more detail than by their function.

  FIG. 4 is a diagram intended to illustrate the type of means to be provided, in a cellular network entity of mobile radiocommunications (in particular

  BSS for "Base Station Subsystem"), in a system according to the invention.

  As recalled in FIG. 4, in an known manner an entity such as the BSS entity comprises so-called air-interface means 20 making it possible: on the one hand to put information originating from a so-called higher level entity 21 of the system considered (in particular NSS, for "Network and Switching Subsystem"), in a form admissible for their transmission on the air interface, - on the other hand to restore information received on the air interface, for

  transmission to said higher level entity 21.

  As described above for the mobile station, the means 20

  interface-air themselves conventionally comprise means of emission-

  reception 22, including baseband processing functions and functions

  radioelectric, and control means 23.

  Said control means 23 make it possible in particular to transmit and receive the various signaling messages exchanged between mobile station and network, in the various procedures, or protocols, provided for operation.

in this network.

  In particular, in the inter-cellular access or transfer method considered here, said control means 23 can in turn comprise: means for carrying out said detections necessary for the implementation of said re-oriented retest function , means for exchanging signaling information with a station

  mobile, so as to perform said re-oriented retest function.

  The detection of a failure during an access or intercell transfer test is an operation which involves concepts well known to those skilled in the art and which therefore does not need to be described here in more detail. The detection that the user is an authorized user can be carried out by interrogating a database of mobile subscribers such as HLR / VLR in a system such as the GSM system for example. The detection that the user is in the preferred zone can for example be obtained by observing the results of radio measurements.

  reported to the network by the mobile station, according to known methods.

  The exchange of information with the mobile station, so as to carry out said re-oriented retest, can use such or such type of procedure, or protocol, already provided for.

in this type of system.

  Since such procedures are well known to those skilled in the art, and the particular implementation of such means also presenting no particular difficulty for those skilled in the art, such means need not be described

  here in more detail than by their function.

  In addition, said control means 23 can also include means for exchanging information with said higher level network entity, so as to ensure that, following the implementation of said re-oriented retest function, the charging for said user is carried out as if this user were in the preferred zone. Such an exchange of information with said higher level network entity can likewise use such or such type of procedure, or protocol, already provided for.

in this type of system.

  In addition, said control means 23 can also include means for monitoring, following the implementation of said re-oriented retest function, so as to redirect the mobile station to a preferred cell as soon as possible, in particular by monitoring the traffic load in the preferred area,

  according to known methods of traffic load monitoring.

Claims (9)

  1. Inter-cellular access or transfer method in a mobile radiocommunication system in which additional services are offered to so-called authorized users in cells known as preferred cells forming a zone known as preferred zone, said method being characterized in that that it comprises the following stages: detection that an inter-cellular access or transfer attempt to preferred cells has failed (1), detection that the user is an authorized user (2), detection that the user is in the preferred area (3),   following such detections, implementation of a retest function   oriented, for inter-cellular access or transfer to a cell outside of this preferred area (4).   2. Method according to claim 1, characterized in that said cell outside of said preferred zone, towards which said re-oriented retest function is implemented, is selected using results of measurements carried out by the mobile station.   3. Method according to claim 2, characterized in that said measurements are carried out by the mobile station on cells which are indicated to it by the   network in a dedicated signaling channel.   4. Method according to claim 3, characterized in that said cells indicated to the mobile station by the network are determined in the network from information including the configuration of the cells of the network and an indication on the location of the mobile station.   5. Method according to claim 4, characterized in that said indication of location of the mobile station is determined in the network on the basis of results   of measurements carried over to the network by the mobile station.   6. Method according to one of claims 1 to 5, characterized in that it is   provided that, following the implementation of said redirected retest function, charging for said authorized user is carried out as if this user were in said preferred area.   7. Method according to one of claims 1 to 6, characterized in that a   monitoring is performed (6), following the implementation of said re-oriented retest function, in order to redirect the mobile station to a preferred cell as soon as possible (7).   8. Method according to claim 7, characterized in that said monitoring   includes monitoring the traffic load in the preferred area.   9. Mobile station for implementing a method according to one of claims 1 to 8, characterized in that it includes means (13) for exchanging signaling information with the network, so as to perform said function of re-oriented re-test.   O. Entity for a cellular mobile radio network, characterized in that it comprises: means (23) for carrying out said detections necessary for the implementation of said re-oriented retest function, means (23) for signaling information exchange with a station   mobile, so as to perform said re-oriented retest function.