FR2894106A1 - Radio channel changing e.g. soft handover, managing method for e.g. wireless local area network, involves selecting radio channel change management process from database based on data assigned to association corresponding to context - Google Patents

Abstract

The method involves determining a communication context among communication contexts of a database with respect to a terminal and based on communication characteristics. A radio channel change management process is selected from the database based on relevant data assigned to an association corresponding to the determined communication context. A radio channel change for the terminal is determined based on the selection. Independent claims are also included for the following: (1) a device for managing changes of a radio channel assigned to a terminal communicating with a communication network (2) a device for managing data utilized for managing a changing of a radio channel (3) a system for managing a changing of a radio channel (4) a computer program installed in radio channel changes managing device (5) a computer program installed in a database managing device.

Description

RADIO CHANNEL CHANGE MANAGEMENT The present invention relates to

  radio networks and more specifically the transfer between two networks of a radio link established between a terminal and an access network. In such networks, there is provided a process whereby a mobile terminal can change the transmission radio channel while maintaining a communication in progress. Such a channel transfer process is commonly called "handover".

  In this type of network, on the other hand, there is the soft handover (SHO) transfer, in which multiple radio links are established simultaneously between the terminal and several neighboring cells for a certain time, which ensures a continuity of communication as well as a diversity of reception in the transient phase, and the transfer of channel with cut or "hard handover" (HHO) in which the communication on the first channel is broken at the moment when the terminal switches to the second channel. Channel transfer mechanisms can be implemented in particular in GSM networks ("Global System for Mobile Communications") and UMTS. They can also intervene between a UMTS type access network and a WLAN type access network or vice versa. It is then a channel transfer between two different access technologies. There may be different reasons for a radio channel transfer. A channel transfer may be triggered when the terminal moves out of the coverage area of the network in which it has an established radio link. This may also be the case when the load on this network is too high to guarantee a certain level of quality of service to the terminal. A channel transfer can also be triggered when the network in which the terminal has a radio channel is not or no longer suitable for the service used by the terminal. Some channel transfer management algorithms take into account a network quality level. Others are based on information about network coverage. Some others rely on a value indicating the network load, the term 'load' of a network indicating a ratio of radio resources used in a network on all radio resources managed in that network. Thus, the load is a value that indicates whether the network is close to being full, or if it can accept new terminals because it is able to allocate new radio channels. US-2004/121777 discloses a radio channel change management method between different networks or between different frequencies, based on a network load determination. This method proposes to decide a change of radio channel according to the load of the network in which the terminal has a radio channel and the telecommunication service used by the terminal on the radio channel considered. Thus, if the load of the considered network reaches a value greater than a threshold value, it triggers a channel transfer to a target network for some terminals. US-6,754,494 discloses a method for avoiding unnecessary channel changes when they are triggered upon detection of a sudden change in a quality level of the transmitted signal on the radio channel allocated to the terminal in question. For this purpose, data relating to the signal quality level is collected between the terminal and a number of base stations. This data is processed to evaluate an improvement in signal quality in case of channel transfer. Thus, based on this evaluation, it is decided whether a channel transfer from the terminal to one of the base stations is relevant. By applying the aforementioned methods, certain radio channel transfers can be triggered while their implementation is ultimately not relevant and does not provide an expected improvement according to a desired criterion. The present invention aims to improve the performance of a radio channel transfer management.

  A first aspect of the present invention provides a radio channel change management method allocated to a communicating terminal in at least one radio communication network, implementing a database comprising associations between radio channel change management processes. and communication contexts in the network, relevance information being respectively assigned to said associations. The method comprises the following steps: / a / determining, relative to said terminal and as a function of communication characteristics, a communication context among said communication contexts of the database; / b / selecting, according to said relevance information assigned to at least one association corresponding to said communication context, a channel change management processing of the database; / c / based on the selected processing, make a decision on a radio channel change for the terminal. The present invention covers various types of radio channel transfer, including hard handover and soft handover channel transfers as set forth above. The present invention can be applied in the context of a change of a radio channel belonging to one network to another radio channel belonging to another network, in the case where the terminal communicates in a plurality of networks for example. It can also be applied in the context of a change from one radio channel to another radio channel, the two radio channels belonging to the same network. This last case can occur between several cells of the considered network, either when the cells operate at the same frequency, or even when they operate at different frequencies. A communication context of the database may comprise a group of communication characteristics relating to the terminal and / or the network in question. Preferably, the relevance information assigned to an association of a communication context with a radio channel change processing, indicates whether, in said communication context, it is relevant according to a given relevance criterion, to apply the radio channel change processing of said association. Thus, the relevance information may relate to a given relevance criterion. Thus, depending on the relevance criterion considered, it may be appropriate to apply a certain radio channel change processing, whereas for another relevance criterion, it may be more appropriate to apply another treatment of radio channel change. radio channel change. Advantageously, such a method thus offers a great flexibility of application. The criterion of relevance can be chosen from at least one of the criteria of the following list: a quality of service offered to the terminal, a terminal rate, a network load.

  Thus, it is possible to give priority to the quality of service or the bit rate that the network offers to a terminal and, as a result, to particularise a network offer according to the terminal to which such a radio channel change management method is applied. . It is also possible to take into account global information to the network or to the plurality of networks in which the terminal is located, to make radio channel change decisions. These various criteria make it possible to further increase the application flexibility of the method according to one embodiment of the present invention. In one embodiment of the present invention, the database management function initializes the database based on estimated data. The present invention covers any type of estimated data for providing initial data to be stored in the database. Such estimated data may in particular result from the implementation of a simulator. These estimated data may also result from experience in implementing the radio channel change processing in the network. The database management function can update the relevance information respectively assigned to the associations of a communication context and a radio channel change processing based on data received after the radio channel change. Under such conditions, the data contained in the database may change throughout the implementation of the method. Such management of the database has the advantage of confirming or correcting the initial data based on data actually collected in the field. Such management is particularly advantageous when the initial data of the database are derived from simulations. This management makes it possible to base the process on data more precise and more correct than those initially stored in the database. Such a method may further include a step of requesting information to implement the selected radio channel change processing. Information of this type, useful for the implementation of the selected processing, can be obtained from the terminal or from the network or one of the networks of the plurality of networks in which or in which the terminal in question is located. Such a step makes it possible to implement a selected processing even if, at the time of selection, for example, all the information required for its implementation is not yet available. In one embodiment of the present invention, each management process included in the database corresponds to a radio channel change algorithm associated with a respective parameterization, combinations of different settings to the same algorithm forming different respective management processes. . Thus, the database may contain several management processes corresponding to the same algorithm to which different parameters are respectively associated. The database can also contain several management processes, each corresponding to a different algorithm with its associated setting. Such parameters may correspond to different thresholds referring for example to a radio coverage criterion, or a load criterion or other. Thus, a radio channel change management processing corresponds to a pair formed of an algorithm and the parameter or parameters associated with it. The database thus comprises several possible treatments to be applied to make a radio channel change decision, some of these treatments being able to correspond to the same algorithm associated with different settings. A second aspect of the present invention provides a radio channel change management device allocated to a terminal, comprising: a determination unit adapted to determine, relative to said terminal and as a function of communication characteristics, a communication context among said contexts communication stored in the database; a selection unit adapted to select, according to said relevance information assigned to at least one association corresponding to said communication context, a channel change management processing of the database; a decision-making unit adapted to, on the basis of the selected processing, make a decision on a radio channel change for the terminal.

  The relevance information assigned to an association of a communication context with a radio channel change processing, can indicate whether, in the communication context, it is relevant according to a given relevance criterion, to apply the change processing radio channel of said association.

  A third aspect of the present invention provides a database management device for use in managing a radio channel change allocated to a terminal, the database having associations between radio channel change management processes and communication contexts in the network, relevance information being respectively assigned to the associations. The relevance information assigned to an association of a communication context with a radio channel change processing, can advantageously indicate whether, in said communication context, it is relevant according to a given relevance criterion, to apply the processing of radio channel change of said association. The relevance information respectively assigned to the associations of a communication context and a radio channel change processing can advantageously be updated according to data received after a radio channel change. A fourth aspect of the present invention provides a radio channel change management system allocated to a terminal comprising: a database management device for use in managing a radio channel change allocated to a communicating terminal in a least one radio communication network, said database comprising associations between radio channel change management processes and communication contexts in the network, relevance information being respectively assigned to said associations; and a radio channel change management device comprising: a determination unit adapted to determine, relative to said terminal and as a function of communication characteristics, a communication context among said communication contexts stored in the database; A selection unit adapted to select, according to said relevance information assigned to at least one association corresponding to said communication context, a channel change management processing of the database; A decision-making unit adapted to, based on the selected processing, make a decision on a radio channel change for the terminal. A fifth aspect of the present invention provides a computer program for installation in a radio channel change management apparatus, including instructions for carrying out the method according to the first aspect of the present invention. during a program execution by means of processing the device. A sixth aspect of the present invention provides a computer program for installation in a database management device, comprising instructions adapted to implement the method according to the first aspect of the present invention, in a execution of the program by device processing means. Other aspects, objects and advantages of the invention will appear on reading the description of one of its embodiments, given below with reference to the accompanying drawings. The invention will also be better understood from the description which follows, with reference to the accompanying drawings, in which: FIG. 1 illustrates an architecture of a plurality of arrays according to an embodiment of the present invention; Figure 2 illustrates a database managed in one embodiment of the present invention; Figure 3 illustrates the main steps of a method according to an embodiment of the present invention; Fig. 4 illustrates a method of using the database according to an embodiment of the present invention; Figure 5 shows a method of using the database with a feedback loop according to one embodiment of the present invention; Figure 6 illustrates a radio channel change management apparatus according to an embodiment of the present invention. In the following, the present invention is described in its application to radio channel changes in a plurality of networks. However, such a description is illustrative and not limiting. An object of the present invention is to provide a mechanism for optimizing a selection of channel transfer processing among a plurality of channel transfer processes available in a plurality of interconnected networks. For this purpose, such a mechanism advantageously takes into account the current communication context in which the terminal is located and / or all or part of the plurality of networks considered. More precisely, according to certain communication characteristics of the networks and / or terminal considered, the mechanism aims to select the most relevant channel transfer processing. By the term 'relevant treatment' is meant processing, which among the plurality of available channel transfer processes is likely to provide the best communication context with respect to a relevance criterion. For this purpose, after having determined a current communication context, it is possible to estimate whether it is relevant to trigger such or such channel transfer processing in the determined communication context, by seeking to estimate the consequences of such a channel transfer. radio. This estimate can be made with respect to one or more relevance criteria, such as, for example, a criterion of relevance relating to a level of quality of service used by the terminal. In such a case, a mechanism according to the present invention aims to estimate whether this level of quality can be improved by the application of one of the channel transfer processes in the context of communication considered. If this is the case, the channel transfer processing is then selected to obtain, in an estimated manner, the best quality level of the service used by the terminal. It is also possible to estimate an improvement of the transmission conditions relative to a criterion of relevance corresponding to some of the networks. For example, a channel transfer processing may be selected by seeking to decrease a load level of the current network, in which the terminal has a radio channel. In this case, we aim to estimate the consequences of applying the various channel transfer processes to the communication context determined by considering the level of load as a criterion of relevance. In this case, it is also possible to take into account the increase of a target network load level provided by each of the channel transfer processes considered for this estimation. Thus, it is then possible to select, for the communication context considered, the channel transfer processing which provides a good compromise between a decrease in the load level on the current network and an increase in the load level on the target network. . Figure 1 illustrates a network architecture according to an embodiment of the present invention. A first telecommunication network 101, of the UMTS type, is connected to a second WLAN type telecommunication network, having a first access point 102 used to increase the coverage and a second access point 103 used to increase the capacity of the network. network. The part referenced 104 representing a non-coverage area of the network 101. FIG. 1 also illustrates a channel transfer management function 100 and a database management function 105, these functions being able to be implemented by the same entity. network entity, or respectively each by a different entity, or each by several entities distributed in the network. A communication context is defined by communication characteristics which may include static characteristics as well as dynamic characteristics, these characteristics being related to the terminal in question, or to one or more of the different networks. For example, it is possible to take into account communication characteristics relating to the network in which the terminal has a radio channel before the channel transfer as well as those relating to the networks potentially considered as targets for a radio channel transfer. The characteristics relating to the terminal, may for example be a type of service used by the terminal or a level of quality of service required by the terminal. These characteristics can also be information that the terminal can obtain by measurements, such as a received power level or a level of interference received, on the current network and possibly on the other networks considered, which can be networks channel transfer targets for the terminal.

  A communication context may also include characteristics relating to the considered networks, which may correspond to radio information such as a charge level, or information relating to the ability of the network to provide a given service and quality of service. Some of these features are static. This is the case, for example, for information corresponding to the capacity of a network to provide a service. Others are dynamic features with relatively short periods of variation. This is the case, for example, for the power level received by the terminal or the load level of a network. Still others may be dynamic and have relatively long periods of variation. This is the case, for example, for a quality of service level required by a terminal. In one embodiment of the present invention, several communication contexts are defined, each of which can combine both communication characteristics relating to the terminal and communication characteristics relating to the networks. Preferably, before triggering a channel change, a mechanism according to an embodiment of the present invention takes into account relevance information assigned to the different channel changes in a given communication context. This channel transfer relevance information is preferably defined relative to a given relevance criterion. Thus, this relevance information makes it possible to indicate whether it is relevant to apply such treatment or not. Applying a treatment in a given context may appear relevant for a certain criterion of relevance and may not appear relevant for another criterion. Thus, for example, a channel transfer can provide in a given communication context, an improvement in the network load and therefore appear to be relevant with respect to this criterion and it can bring a deterioration with regard to the service used by the terminal, and therefore appear to be irrelevant to this criterion.

  Since the relevance of a channel transfer processing is therefore relative, advantageously the relevance information assigned to each of the associations of the database is relative to a given relevance criterion.

  Therefore, preferably, this relevance information is assigned to a set comprising a communication context, a channel transfer processing and a relevance criterion. They then indicate a level of probability with which the triggering of the considered channel transfer in the determined communication context will bring an improvement corresponding to the criterion of relevance considered. With such arrangements, it can be decided to trigger a channel transfer only in cases where it is highly likely that the channel transfer allows an improvement corresponding to a known relevance criterion.

  Thus, advantageously, it is therefore possible to avoid triggering a channel transfer when the relevance information indicates that it would probably not be appropriate to do so. By avoiding triggering certain channel changes, it also prevents the terminal from taking unnecessary steps. Indeed, as a rule, when triggering a channel change, the terminal is requested to perform measurements and send information to an entity that manages the channel transfer and that requires these measures to implement the channel transfer decided. In one embodiment of the present invention, a database is managed to associate a plurality of communication contexts respectively with a plurality of channel change processes, associations of a given communication context and a channel transfer processing are preferably respectively assigned relevant information such as those described above. Thus, depending on the data managed in this database, it is possible to trigger channel changes that have a high probability of improving transmission conditions, corresponding to the criterion of relevance, in the plurality of networks considered.

  FIG. 2 illustrates a structure of such a database according to an embodiment of the present invention in which a single relevance criterion is taken into consideration for selecting a radio channel transfer processing. This database 200 includes four 201-204 communication contexts and three 205-207 channel transfer processes. It further includes relevancy information relating to certain associations between a communication context and a radio channel transfer processing. Thus, the association corresponding to the communication context 201 with the processing 205 is assigned a relevance information p1, and the association of the communication context 201 with the channel transfer processing 206 is assigned a relevance information. p2. In such a case, if it is determined that the current communication context relative to the terminal in question approaches the transmission conditions of the communication context 201, it is possible to select the processing, among the processing 205 and the processing 206, which corresponds to the relevance information the best among p1 and p2. Then, it is advantageous to apply the channel transfer processing thus selected to the terminal in question. It is easy to deduce the other possible scenarios, according to the communication context determined for the terminal considered. The other associations illustrated by this figure are: the association of the communication context 202 with the processing 205 assigned the relevance information p3; associating the communication context 202 with the processing 206 assigned the relevance information p4; the association of the communication context 203 with the processing 206 assigned the relevance information p5; the association of the communication context 203 with the processing 207 assigned the relevance information p6; associating the communication context 204 with the processing 206 assigned the relevance information p7; the association of the communication context 204 with the processing 207 assigned the relevance information p8.

  In one embodiment of the present invention, a database having a structure of the type of that described above is managed, in a first and a second main phases, by applying one of the well-known learning methods of the man of the art, such as a Bayesian type of learning method. The first phase corresponds to the initialization of the data in the database and the second phase corresponds to an update of the database following its use by the radio channel transfer management function, thanks to the evaluation. criteria of relevance of the radio channel transfer. Such an update may advantageously correspond to a correction, and therefore an improvement, of the database on which the decision to change the radio channel is based. We define different learning classes. Thus, for a treatment, denoted Processing, parameterized with parameters referenced Parameterization, a class referenced Class (Processing, Parameterization) contains the communication characteristics relating to the terminal and the communication characteristics relating to the networks that make it possible to obtain the greatest probability. that a channel transfer carried out according to the Processing treatment with the Parameter setting parameterization is a relevant channel transfer with regard to a criterion of relevance determined. A specific class can be created to represent the case where no channel transfer is relevant, that is to say that the triggering of any channel transfer does not make it possible to obtain an improvement according to the criterion of relevance. considered with a probability greater than a specified threshold.

  These different classes can be obtained by a learning method, of the Bayesian learning method type, which takes as input all the communication characteristics relating to the terminal and the networks considered. This set is then divided into Class classes (Processing, Parameterization). Preferably, for this class determination step, a limited and predefined number of channel change processes is considered, and the parameters associated with each process vary within a predefined value range. It is possible that some classes are not significant, this is particularly the case when the setting is not adapted. We can define a class of training Class (Processing, Parameterization) so that it maximizes the probability that the treatment Treatment and its parameterization are relevant in the context of communication considered and with respect to the criterion of relevance taken as reference. It is noted that the more the number of communication characteristics considered is important, the more one is led to make a fine classification, and the greater the number of classes to manage. It is therefore advantageous to determine a compromise between a fine classification and a management complexity. Then, in such a case, depending on the class to which the terminal belongs, one is able to make a decision when to the channel transfer processing to be applied to the terminal. In the second phase of management of the database, by application of learning methods, it is still advantageous to update the data stored in the database according to the information, preferably received from the terminal or from the networks. After a channel transfer has been initiated to control the actual relevance of the channel transfer performed in the detected communication context. Figure 3 illustrates the main steps of a radio channel change management method according to an embodiment of the present invention. In a step 30, it is expected to receive information relating to communication characteristics taken into account to define the communication contexts stored in the database 200. When such information is received, in a step 31, a communication context among the different communication contexts stored in the database. This step aims to represent the current transmission conditions of the terminal by a predefined communication context and stored in the database. Thus, for example, the communication contexts can be defined by communication characteristics on the one hand relating to the coverage and the load of the current network in which the terminal is located, and on the other hand relating to the coverage and the load of a neighboring network of the current network. In such a case, different communication contexts may be stored in the database, each indicating different respective coverage and load values for the two networks. Then, the channel transfer management function 100 is based on the data available to it with regard to the load and the coverage of the current network of the terminal, for example the UMTS network 101, and of a neighboring network, for example the WLAN 102, to determine the communication context stored in the database that is closest to the current transmission conditions of the terminal.

  In a step 32, a channel transfer processing is selected according to the context thus determined and associated relevance information stored in the database. Then, in a step 33, it is decided according to the selected channel transfer processing, if one triggers a channel transfer or not.

  In the case where it is decided not to trigger a channel change, it returns to step 30 (arrow n). In the opposite case (arrow o), a channel transfer is carried out in step 34 before returning to step 30. If some information is required to apply the selected channel transfer processing and is not available for the selected channel transfer processing channel change management entity, they are then requested to the terminal and / or networks. For this purpose, the channel transfer management function can send a notification to the terminal and / or the networks concerned by the future channel transfer, this notification containing a list of information required for the implementation of the transfer processing. selected channel, and that the channel transfer management function does not have yet. For example, if the controlling entity selects a network dependent load transfer processing, a notification is sent to the different networks to request information on their respective load. If, the channel transfer management function selects a channel transfer processing dependent on characteristics relating to the signal received by the terminal, a message is sent to the terminal to indicate certain measures to be performed, and the conditions under which the information relating to these measurements can be traced back to the channel 100 transfer management function. Such information can be obtained by exchanging messages between the networks and the entity responsible for the channel change, if they are related to the networks. They may also be sent from the terminal either directly to the channel change management entity, or via the network currently serving the terminal, if necessary after the terminal has made certain measurements. Note that the present invention is independent of the way in which this information is requested and reported to the channel transfer management entity which can also be a distributed entity in the various networks, or centralized. The present invention covers any type of architecture for implementing such a channel transfer management method on the basis of message exchanges between a channel change management function, the different networks and the terminal. Thus, in one embodiment of the present invention, it is therefore possible to limit the number of measurements and the amount of information to be traced from the terminal to the channel transfer management function to the information considered to be the most important. relevant. The battery consumption of the mobiles is then reduced, since they have fewer measurements to be made, as well as the amount of signaling exchanged between, on the one hand, the terminals and the networks, and on the other hand the networks and the function. radio channel transfer management.

  In one embodiment of the present invention, the management of the database may be stated in a first and a second phase. Figure 4 illustrates such management of the database.

  In the first phase 400, in a step 402, the database 200 is initialized with data obtained either by experiment, notably by implementing measurements in the field, or theoretically, so as to structure the data like this. is described with reference to FIG.

  This initialization phase can therefore be based either on field tests or on the results of network simulations modeling the behavior of the network. A possible methodology for filling database structures with a network simulator is to test each processing and associated parameterization under various load and coverage conditions, and then compare the results obtained for each channel transfer in order to assigning a relevance coefficient, or relevance information, to an association of a communication context and a radio channel transfer processing. For this purpose, Bayesian-type learning methods may advantageously be used.

  Then, in the second phase 401, in a step 403, the database is used by the channel transfer management function which implements a method according to the invention as described with reference to FIG. phase of use, advantageously, for each terminal, depending on communication characteristics of the networks and / or the terminal, it is evaluated, according to the database, if it would be appropriate to trigger a channel transfer for this terminal with one of the processing associated with the communication context best representing the current communication characteristics of the terminal, whether these characteristics are related to the terminal itself or to the various networks considered. Then, in the case where it is concluded to the opportunity to trigger a channel change, note the results obtained after the channel transfer so as to update in a step 404, if any, the data of the database 200, such as the relevance coefficient assigned to the association corresponding to the channel transfer performed, or the parameterization of the selected channel transfer processing. Then, the process is reapplied by step 403 based on the thus updated database.

  Thanks to this feedback mechanism of the management of the database, as illustrated by the link 405, it is advantageously able to refine, specify or even correct a posteriori the stored data, all during the implementation of a method according to the invention.

  The present invention covers all the ways of carrying out the message exchanges between the terminal and the channel change management function, as well as between the different networks and this same function. The information contained in these messages may relate to the communication characteristics of the networks and the terminal, which may be static, or vary dynamically during a communication in progress. Fig. 5 is a diagram showing these different message exchanges in one embodiment of the present invention. The channel transfer management function 100 receives information 56 relating to the terminal and to the networks considered. This information 56 can be sent by the terminal and then correspond to characteristics 54 relating to the quality of service and radio conditions measured. This information 56 can also be sent by the networks and then correspond to characteristics relating to the load 55.

  The management function of the database 105 receives information, according to a feedback loop 53, which makes it possible to update the information contained in the database according to the changes that occur in the transmission conditions of the terminal and networks following a channel transfer triggered by the radio channel transfer management function. In this way, it is advantageous to receive information relating to the consequences of a channel transfer in a given communication context. The relevance information can then be updated according to the relevance criteria considered as a function of this information received a posteriori of the radio channel transfer.

  Moreover, when a channel transfer has been decided, the channel transfer management function 100 can generate, in certain cases, messages 51 intended for the terminal and / or networks for requesting information to implement a transmission. selected channel transfer processing. The channel transfer management function can receive dynamic information such as the power of the signal received by the terminal from all or part of the networks of the plurality of networks considered, the load of the networks likely to be affected during the change of channel, the Quality of Service requested by the terminal for the current communication, a proportion of the load of a network reserved for a type of service.

  This channel transfer management function can also receive static information such as maximum transmission power on each network, the ability of a network to provide a given service, a priority level attached to the terminal. These examples are given for illustrative purposes and are not limiting.

  Thus, depending on the data as structured in the database, the channel transfer management function selects the channel transfer processing which is considered to be best suited, with a suitable parameterization. In one embodiment of the present invention, for the attribution of information of relevance to the various associations stored in the database, reference may be made, for example, to a criterion of relevance relating to the quality of service at the level of the database. terminal considered. A channel transfer is then considered relevant, or useful, if it increases the quality of service at the terminal. In this case, we can assign a relevance information in the form of a number to each association, the highest number meaning that the association to which it is assigned is the most adapted to this criterion of relevance. It is also possible to consider a criterion of relevance relating to the load of the networks, in particular that of the current network in which the terminal has a radio channel and that of the target network of the channel transfer under consideration. In this case, for example, the relevance information assigned to a given association of a communication context and a channel change processing takes into account the decrease of the load of the current network and the increase of the load. the target network resulting from the application of this processing in this communication context. In one embodiment of the present invention, the channel transfer management function takes into account several criteria of relevance, preferably in a hierarchical manner, that is to say that the various criteria of relevance are considered one of the following: after the other in order to allow a selection of channel transfer processing if, in view of the criteria of relevance previously considered, it is not easy to select one.

  It is also possible to provide that, upon updating the relevance information in the database, the communication contexts are modified or corrected. Figure 6 illustrates a radio channel change management device 60 comprising a determination unit 61, a selection unit 62 and a decision unit 63 according to an embodiment of the present invention. The following sections illustrate an example of application of a method according to an embodiment of the present invention in which a UMTS type network (for 'Universal Mobility Telecommunication System') comprising for example three cells and a WLAN type network ( for 'Wireless Local Area Network') with two access points. The database includes a first channel transfer processing THO1 taking into account the network coverage to decide on a radio channel transfer. According to this first processing, if a value representing a level of reception of a coverage indicator on the current network of the terminal is less than a current threshold value Tcuv, and if a value representing a level of reception of a coverage indicator on the target network is greater than a threshold value Tcouv_cible, then the channel transfer is triggered. The database includes a second channel transfer processing THO2 taking into account the load of the current and target networks so that, if a value representing a current network load level is greater than a current load threshold value Tc, and a value representing a charge level of the target network is less than a threshold value Tcharge_cible, then the channel transfer is triggered. In this example, three relevance criteria are taken into account hierarchically. The first criterion of relevance, considered in this example as the most important, relates to a degradation of the quality of service provided to the terminal. The second criterion of relevance is relative to the load of the two networks and it aims to avoid an overload of the target network while decreasing a load of the current network. The third criterion of relevance is applicable to the terminal operating in data mode and relates to the bit rate supplied to the terminal. Thus, this third criterion aims to maintain or increase the flow offered to the terminal. A communication context is defined by a first and a second characteristic, respectively character1 and character2, relating to the terminal as well as a third and a fourth characteristic, respectively character and character, relating to the networks. The first communication characteristic corresponds to the current network of the terminal and the second characteristic corresponds to a value representing the reception level of a coverage (or distance) indicator on the current network. The third characteristic corresponds to the load of the UMTS network and the fourth communication characteristic corresponds to the load of the WLAN network. During the initialization phase of the database by a network simulator, in a first simulation, only the THOI processing is used, by varying the parameters Tcouv_actuel and Tcouv_cible. Then, in a second simulation, the THO2 processing is used, by varying the parameters Tcharge_actuel and Tcharge_cible. For each inter-network channel transfer, one score out of five is given for each relevance criterion, indicating a significant relevance of the considered channel transfer and a low relevance of the considered channel transfer, the relevance of a channel transfer. indicating the usefulness of channel transfer in the context of communication considered in relation to a given relevance criterion.

  Treatment Background First Second Third Handover Criteria Criterion Criterion (ctx) Communication Relevance: Relevance: Relevance: Load quality on the offered network service flow maintained at the current terminal, with no or increased load increase on the Ctxl target network: THO1, 5 {character: UMTS; param1 character2: UMTS coverage bad; character3: good UMTS load; character4: good WLAN load} THO2, no triggered channel transfer param2 Ctx2: THO1, 5 4 5 {character: UMTS; param1 character2: UMTS cover bad; character3: bad UMTS load; char: good WLAN load} THO2, 5 param2 Ctx3: THO1, 3 1 3 {character: UMTS; param1 character2: UMTS cover bad; character3: bad UMTS load; character4: WLAN load bad} THO2, No channel transfer triggered param2 Ctx4: THO1, No channel transfer triggered {character: UMTS; param1 character2: UMTS cover bad; character3: bad UMTS load; character4: good WLAN load} THO2, 3 5 3 param2 CtxS: THO1, No triggered channel transfer {character: UMTS; param1 chars2: good UMTS coverage; character3: bad UMTS load; character4: good WLAN load} THO2, 2 5 3 param2 Ctx6: THO1, No triggered channel transfer {character: UMTS; param1 chars2: good UMTS coverage; character3: bad UMTS load; char: good WLAN load} THO2, 5 Param2 Ctx7: THO1, 5 4 3 {character: WLAN; param1 character2: WLAN cover bad; character3: bad WLAN load; character4: good UMTS load} THO2, 5 5 3 Param2 In such an example, if the channel transfer management function determines that the terminal is in the UMTS network, with poor network coverage and a good load, and that the WLAN also has a good load, this channel transfer management function can deduce that the terminal is in the first communication context listed in the table above, Ctxl. For this context, the database 200 holds information on the two THOI processes with parameter param1, and TH02 with parameter param2. The probability that the application of the THO1 treatment in the context of communication ctxl, brings an improvement with respect to the first criterion of relevance, is represented by a coefficient of relevance of 5, that is to say that it is very strongly likely that such a channel transfer is relevant to this first criterion of relevance. On the other hand, the database indicates that the application of the TH02 channel transfer processing to the communication context ctx1 does not trigger a channel transfer and thus the application of the TH02 treatment does not improve the transmission conditions in the communication context. which terminal is located. Thus, advantageously, the channel transfer management function 20 will select the THO1 processing with its parameter param1. Therefore, a channel transfer is triggered. After the channel change, when a new radio channel is allocated to the terminal, the corresponding data is advantageously updated in the database 200, as described in a previous section. It is possible for the channel transfer management function to determine that the communication context closest to the transmission conditions in which the terminal is located is the context ctx2 of the database. In this case, with regard to the first criterion of relevance, it is not easy to select a treatment between THOI and THO2. The channel transfer management function can then refer to the second selection criterion and thus select the THO2 channel transfer management processing with its parameter param2 which appears to be the most relevant in this given context. Thus, a method according to an embodiment of the present invention can be very advantageous, both at the level of the terminals and at the level of the networks themselves.

  The implementation of such a method is simple. It requires a structured and managed database as described in the previous sections, as well as a function that is in charge of the management of channel transfers and which is related to the database.

Claims (14)

  A radio channel change management method allocated to a communicating terminal in at least one radio communication network, implementing a database (200) having associations between radio channel change management processes and context communication in said network (201-204), relevance information being respectively assigned to said associations; said method comprising the steps of: / a / determining (31), relative to said terminal and as a function of communication characteristics, a communication context among said communication contexts of the database; / b / selecting (32), based on said relevance information assigned to at least one association corresponding to said communication context, channel change management processing of the database; / c / on the basis of the selected processing, make a decision (33) on a radio channel change for the terminal.   2. The method according to claim 1, wherein the relevance information assigned to an association of a communication context with a radio channel change processing indicates whether, in said communication context, it is relevant according to a criterion of relevance. given, to apply the radio channel change processing of said association.   3. Method according to claim 2, wherein the criterion of relevance is selected from at least one of the criteria of the following list: a quality of service offered to the terminal, a terminal rate, a network load.   The method of claim 1 or 2, wherein the database management function initializes (400) said database based on estimated data.   The method of claim 1 or 2, wherein the database management function updates (401) the relevance information respectively assigned to the associations of a communication context and a channel change processing. radio based on data received after the change of radio channel.   The method of claim 1 or 2, further comprising a step of requesting information to implement the selected radio channel change processing.   7. The method of claim 1 or 2, wherein each management process included in the database corresponds to a radio channel change management algorithm associated with a respective parameterization, associations of different settings to the same algorithm forming different respective management treatments.   A radio channel change management device (60) allocated to a communicating terminal in at least one radio communication network, said database operating device (200) having associations between change management processes. radio channel and communication contexts in the network (201-204), relevance information being respectively assigned to said associations; said device comprising: a determining unit (61) adapted to determine, relative to said terminal and as a function of communication characteristics, a communication context among said communication contexts stored in the database; a selection unit (62) adapted to selecting, based on said relevance information assigned to at least one association corresponding to said communication context, channel change management processing of the database; a decision-making unit (63) adapted to, on the basis of the selected processing, make a decision on a radio channel change for the terminal.   The radio channel change management apparatus according to claim 8, wherein the relevance information assigned to an association of a communication context with a radio channel change processing indicates whether, in said communication context, it is relevant according to a given relevance criterion, to apply the radio channel change processing of said association.   A database management device (200) for use in managing a radio channel change allocated to a communicating terminal in at least one radio communication network, said database including associations between change management processes. radio channel and communication contexts in the network (201-204), relevance information being respectively assigned to said associations; said relevance information indicating whether, in said communication context, it is relevant according to a given relevance criterion, to apply the radio channel change processing of said association.   The database management device according to claim 10, wherein the relevance information respectively assigned to the associations of a communication context and a radio channel change processing are updated (401) according to data received after a radio channel change.   12. Radio channel change management system allocated to a communicating terminal in at least one radio communication network, said database operating system (200) having associations between radio channel change management processes and communication contexts in said networks (201-204), relevance information being respectively assigned to said associations; said system comprising: a database management device (200) for use in managing a radio channel change allocated to a communicating terminal in at least one radio communication network, said database including associations between processes radio channel change management system and communication contexts in said networks (201-204), relevance information being respectively assigned to said associations; and a radio channel change management device comprising: a determination unit (61) adapted to determine, relative to said terminal and as a function of communication characteristics, a communication context among said communication contexts stored in the database ; A selection unit (62) adapted to select, according to said relevance information assigned to at least one association corresponding to said communication context, a channel change management processing of the database; A decision-making unit (63) adapted to, on the basis of the selected processing, make a decision on a radio channel change for the terminal. 15 20 25 30   13. Computer program intended to be installed in a radio channel change management device, comprising instructions able to implement the method according to any one of Claims 1 to 7, during execution of the program by device processing means.   14. Computer program intended to be installed in a database management device, comprising instructions able to implement the method according to any one of claims 1 to 7, during execution of the program by device processing means.