WO2007042663A1

WO2007042663A1 - Method for connection between ip sub-networks and mobile terminal

Info

Publication number: WO2007042663A1
Application number: PCT/FR2006/002274
Authority: WO
Inventors: Luis Ignacio Escobar Sanz; Julien Riera
Original assignee: France Telecom
Priority date: 2005-10-13
Filing date: 2006-10-10
Publication date: 2007-04-19
Also published as: EP1935141A1

Abstract

The invention concerns a method for connecting a mobile terminal (STA) to an IP network via a radio access point (AP). Following a searching step (P_Req), (P_Rep) and for each radio access point (AP) locally associated with an external IP agent (FA) forming an accessing pair n{AP + FA}, the method consists in transmitting to the mobile terminal (STA) an information message (P_A), including at least the IP address of the external agent (FA), then after determining the selection of the accessing and authenticating pair (A_R), (A_S), inhibiting transmission by the radio access point (AP), then by the mobile terminal (STA) of an association response message respectively an OSI level 3 message to an external IP agent, transmitting from the mobile terminal (STA) to the radio access point (AP) of the selected accessing pair an association request (R_Req) and an association registration request (R_Reg) containing the registration data, transmitting from the external agent (FA) to the home agent (HA) of the mobile terminal (STA) a registration request (Req_Reg) and upon reply of registration (Reg_Rep), transmitting from the external IP agent (FA) to the mobile terminal (STA) an association response message (R_Rep). The invention is useful for optimizing connection between WiFi mobile terminals.

Description

METHOD FOR CONNECTION BETWEEN IP SUB-NETWORKS AND MOBILE TERMINAL

The invention relates to a method of connection between subnetworks

IP and mobile terminal, via radio access points and access torque to a corresponding IP network.

When the mobile terminal, by displacement, changes the radio access point to the IP network, this radio access satisfying for example the IEEE 802.11 recommendations, and in the case where each subnetwork

IP is associated with a single radio access point, the aforementioned mobile terminal further changes IP subnet.

In order to guarantee the continuity of session, the mobile terminal must then carry out two procedures of connection or transfer of connection, "handover" in English, a first transfer of connection at the level of the layer 2, level link or "link layer In English of the OSI model and a second connection transfer at layer 3, network level or "network layer" in English of the OSI model.

Thus, with reference to FIG. 1 relating to the connection transfer procedures of the prior art,

the time of transfer of connection at level 2, time of passage from one access point AP to another, implements four successive steps:

- P_d, where the mobile terminal scans all or part of the 14 channels of the radiofrequency band, 2, 4 GH ₂ in the case of the IEEE 802.11 recommendation;

- D_d, where the mobile terminal chooses the best access point AP in terms of quality of the radio frequency signal received or others, SSID, security (presence of WEP or not, etc.);

- A_d, where the mobile terminal must authenticate with the AP access point retained;

- R_d, where the terminal connects to the AP access point retained.

- the connection transfer time FA_d at level 3, corresponding to the time to change from level 3 of an IP subnet to level 3 of another IP network. When Mobile IPv4 protocol is used, this time is shown in Figure 1 above. This time results, on the one hand, from the need to allocate a temporary IP address to the mobile terminal via an external agent FA, for "foreign agent" in English (messages A.Sol and A.Adv on Figure 1) and then register the mobile terminal with its temporary IP address with its home site agent HA for "home agent" in English (Req_Reg messages in Figure 1). With reference to FIG. 1, the various message exchanges between an mobile terminal STA, an access point nAP, an external IP agent FA and the originating site agent HA of the mobile terminal STA are noted: P_Req, message access point search for Probe Request in English; P_Rep, search response message for Probe Response in English;

A_R, authentication request for Authentication Request in English; A_S, Authentication Success Response for Authentication Success in English; R_Req, reassociation request for Reassociation Request in English; R_Rep, reassociation response for Reassociation Response in English; A_sol, external agent solicitation message for Agent Solicitation in English;

A_adv, mobile device information message for Agent Advertisement in English;

Reg_Req, registration request for Registration Request in English; Reg_Rep, registration response for Registration Response in English. Their succession generates, during a connection or a transfer of connection, the aforementioned delays P_d, D_d, A_d, R_d and FA_d, ie the delay of connection or transfer of connection L2 by message exchange at level 2 OSI between the mobile terminal STA and the access point nAP, increased connection connection delay or L ₃ connection transfer by OSI level 3 message exchange between the mobile terminal STA and the external agent FA, and then between the mobile terminal and the original site agent HA, relayed by the external agent FA.

Other devices implement other IP mobility protocols.

This is the case, for example, with the TAP DANCE protocol, implemented at the level of access points marketed by ATMEL.

The aforementioned TAP DANCE protocol makes it possible to provide connection transfer to mobile terminals between IP subnetworks, but also between access points of the same sub-network that satisfies the IEEE 802.11f standard.

During the connection transfer times L ₂ and L ₃ as illustrated in FIG. 1, the client mobile terminal can neither transmit nor receive data. In addition, with the techniques of the prior art, the aforementioned connection transfer time exceeds the limit of the delay time allowable for real-time applications such as the transmission of the speech signal on the IP network, also referred Vo IP ₁ the aforesaid delay of delay being between 100 and 200 ms, depending on the type of conversation exchanged.

The object of the present invention is to overcome the aforementioned drawbacks of the prior art, with the aim of minimizing the connection or connection transfer time between IP subnetworks and to cause as little data packet loss as possible. In particular, an object of the present invention is from a grouping in one pair of the functionalities of an access point AP at level 2 and those of an external agent FA of the Mobile! Pv4 protocols at level 3 , each element of the pair operating at level 2, for the access point part AP, respectively at level 3, for the external agent part FA, to optimize connection time or connection transfer, unlike existing equipment currently integrating these features but for which connection times are close to time obtained with AP access point equipment, separate FA external agent.

More particularly, an object of the present invention is to improve the connection transfer time from one IPv4 subnet to another IPv4 subnet, when each of these subnetworks is associated with a single access point. IEEE 802.11 AP, including 802.11b, 802.11g,

802.11a or other, through the implementation of a method, a combination of Level 2 connection transfer procedures, corresponding to the IEEE 802.11 standard and Level 3 connection transfer procedures, corresponding to the existing Mobile IPv4 standard .

Another object of the present invention is also the application of the aforementioned method, within the framework of an architecture implementing the ADSL accesses of private mobile terminal users, coupled to radio access points, each point of access. access corresponding to a different IPv4 subnet.

Another object of the present invention is also the application of the aforementioned method, in the context of an architecture implementing a plurality of access points, belonging to a wireless local area network, WLAN, each of the points. radio access corresponding to a different IPv4 subnet.

The method of connection between a mobile terminal and an IP subnetwork via a radio access point, object of the invention, in which the mobile terminal comes into communication, on the one hand, with this point radio access via OSI level 2 messages, and on the other hand with an external IP agent via level 3 messages

OSI, is remarkable in that each radio access point is locally associated with an external IP agent to form an access pair, following the execution of a radio access point search step by this mobile terminal. in which the radio access point of each radio access couple transmits to this mobile terminal a search response message, this method comprises at least the transmission of each pair of access to the mobile terminal of an intelligence message comprising at least the IP address of the external agent of the pair of access, and, following a decision process of choice of the access couple access point by this mobile terminal and a successful and committed authentication procedure between the mobile terminal and the radio access point of the mobile terminal. chosen access couple, the inhibition of the transmission by the radio access point of the selected access torque to the mobile terminal of any association response message, and, by this mobile terminal of any message at level 3 OSI to an external IP agent, the selective transmission of the mobile terminal to the access point of the selected access couple of an association request and an association registration request, this registration request of association containing the registration information mobile terminal to the originating mobile terminal agent, transmitting the external IP agent of the selected access couple to the home site agent of the mobile terminal, to which a temporary address has been sent. assigned to a registration request message and, upon receipt of a registration response message from the mobile terminal site agent by this external IP agent, the transmission of the external IP agent to the mobile terminal of an association response message between the radio access point of the chosen access couple and this mobile terminal, which makes it possible to optimize the total connection time by eliminating the transmission and transmission delay. response of any OSI level 3 message to an external IP agent. The method which is the subject of the invention is furthermore remarkable in that it consists in anticipating the transmission of the request message recording the external IP agent of the chosen access couple to the agent of the site of origin of the mobile terminal prior to the transmission by the mobile terminal of the reassociation request. This makes it possible to conduct in parallel the connection registration operation with the agent of the mobile terminal's home site and the reassociation operation conducted between the mobile terminal and the access couple's radio access point. selected. The pair of access to an IP network from a mobile terminal by radio link, object of the invention, comprises a radio access point and an external IP agent locally associated with this radio access point.

It is remarkable that, in addition to an input / output member connected to the IP network and a central processing unit, this access pair includes at least one creation and transmission module to any mobile terminal requesting a message. of information, comprising at least the IP address of this external IP agent, and a management module by inhibiting the transmission by the radio access point of this access pair of any association response message to a terminal mobile, and, consequently, of inhibition by any requesting mobile terminal of the transmission of any message at the OSI level 3 to any external IP agent, in particular to the external IP agent associated locally with this radio access point forming this access couple. The access torque to an IP network from the mobile terminal by radio link, which is the subject of the invention, is also remarkable in that it furthermore includes a module for creating and transmitting the external IP agent of this invention. access torque to the originating site agent of a requesting mobile terminal of a registration request message and a creation and transmission module of the external IP agent to that requesting mobile terminal of a association response message between the radio access point of this access pair and the requesting mobile terminal.

The method and the couple of access to an IP network from a mobile terminal by radio link, objects of the invention, find application to the connection respectively to the connection transfer of any mobile terminal equipped with a link resource WiFi type radio, IEEE 802.11, vis-à-vis an access pair equipped with a corresponding radio access point associated locally with an IP agent of any type, including an ADSL modem, a router connected to the INTERNET via a LAN enterprise network for example.

The method and the access couple will be better understood on reading the description and on the observation of the following drawings in which, in addition to the FIG. 1, relating to the prior art:

FIG. 2 represents, by way of illustration, a timing diagram of implementation of the method that is the subject of the invention in a first nonlimiting implementation mode; FIG. 3 represents, by way of illustration, a time diagram of the implementation steps of the method that is the subject of the invention in a second nonlimiting implementation mode;

FIG. 4 represents, by way of illustration, a block diagram of an access torque to an IP network from a mobile terminal by radio link, object of the invention;

FIG. 5a represents, by way of illustration, a first example of use of the method and of an access couple that is the subject of the invention;

FIG. 5b represents, by way of illustration, a second example of use of the method and of an access couple which is the subject of the invention.

A more detailed description of the method of connection between a mobile terminal and an IP subnetwork via an AP radio access point, in which method the mobile terminal enters into communication, on the one hand, with the point aforementioned radio access via OSI level 2 message and, on the other hand, with an external IP agent FA via OSI level 3 message, in accordance with the object of the present invention, will be now given in connection with Figure 2 and the following figures.

In general, it is indicated that a mobile station STA constituted by a portable computer equipped with a radio link equipment of the WiFi type, for example, and therefore capable of connecting to an IP subnet via of an AP access point among a plurality of nAP access points, where appropriate to a plurality of corresponding external IP agents, is likely to connect for the first time to one of the aforementioned IP subnetworks or successively during a roaming route of this mobile terminal among the IP sub-networks thus formed.

In general, it is indicated that each radio access point AP is locally associated with an external IP agent FA to form an access pair, each access pair being noted {AP + FA} among a plurality of access pairs denoted n {AP + FA}.

Conventionally, it is indicated that, in order to execute a connection or a reconnection, the mobile terminal STA performs a step of searching AP radio access points, a step in which the AP radio access point of each pair of access n {AP + FA} transmits to the mobile radio terminal a search response message in a conventional manner.

In Fig. 2, the mobile terminal STA transmits a radio access point search message P_Req and receives a search response message P_Rep to one or more of the radio access points and finally available access pairs AP + FA}.

As shown in FIG. 2 and remarkably, the method which is the subject of the invention includes at least the transmission of each access pair {AP + FA} of the plurality of access pairs n {AP + FA} to the mobile terminal STA, and following the reception of the radio access point search message and then of the transmission of the search response message, of an intelligence message marked P_A comprising at least the IP address of the IP agent External AF of the corresponding access pair {AP + FA}.

In these conditions, it is understood that the search time D_d is not significantly increased since it simply corresponds to the additional transmission of the information message P_A for each access couple likely to respond to the search message of the points of interest. radio access.

As further represented in FIG. 2, following a decision process of choosing an access point AP of an access pair {AP + FA} by the mobile terminal STA, this decision process can be conducted conventionally, then following an authentication procedure consisting for example, as shown in FIG. 2, when the mobile terminal STA sends an authentication request A_R and then receives from the data point considered AP access chosen by the STA mobile terminal a A_S authentication success message, the authentication procedure being engaged and successful between the mobile terminal STA and the radio access point of the chosen access couple {AP + FA}, the method, object of the invention, then consists in performing an inhibition of the transmission by the radio access point of the access couple chosen following the reception by the radio access point by the access point AP considered of an association request respectively of reassociation, denoted R_Req, of any association response message respectively reassociation to the mobile terminal and, consequently, by the terminal STA considered, of any OSI level 3 message to an external IP agent and in particular to the agent External IP FA of the access pair {AP + FA} chosen.

Thus, with reference to FIG. 2, the method according to the invention comprises, as represented in the above-mentioned figure, after the authentication period D_d of the authentication procedure, the transmission by the mobile terminal STA of the association request in the case of a first connection, respectively of a reassociation message in the case of a connection transfer of the association request denoted R_req and then, immediately and without any further delay, the selective transmission of the mobile terminal STA to the access port access point of an association registration request marked R_Reg to the selected access pair {AP + FA}.

According to a remarkable aspect of the object of the method which is the subject of the invention, the association registration request R_Reg contains the registration information of the mobile terminal STA with the agent of the home site HA of the mobile terminal in question. .

By way of nonlimiting example, it is recalled that any mobile terminal STA capable of executing itinerant operations, is managed from the point of view of its addressing, in particular for the transmission of messages in a local network, from an identifier and an originating address assigned by the originating site agent HA of the mobile terminal.

Following reception, by the external IP agent FA of the chosen access pair, of the association registration request R_Reg, the IP agent external can then, in accordance with a remarkable aspect of the method of the invention, proceed to the transmission of a registration request Reg_Req to the agent of the original site HA of the mobile terminal STA to which a temporary address has been assigned . On receipt by the external IP agent FA of the selected access couple

{AP + FA} of a registration response message Reg_Rep, the method which is the subject of the invention then consists in transmitting the external IP agent FA of the selected access pair to the mobile terminal STA, an association response message R_Rep between the AP radio access point of the selected access pair {AP + FA} and the requesting connection or reconnection mobile terminal STA.

The operating mode described in connection with FIG. 2 relating to the implementation of the method, object of the invention, thus makes it possible to optimize the total connection time by eliminating the transmission and response delay of any message at level 3 OSI to an external IP agent not located a priori. Indeed, because of the local association of an external IP agent FA to an AP access point to the same address to form an access couple, the method of the invention thus reduces the delay of Reassociating and recording R_R_d in Figure 2 to transactions between mobile terminal STA and access couple {AP + FA}, and access torque above to the HA agent of the original site of the mobile terminal STA by transmission of OSI level 2 messages, as will be described later in the description.

It is understood, in particular, that thanks to the implementation of the method, subject of the invention, the connection or connection transfer delays are obtained by suppressing the transmission of OSI level 3 messages by integration into OSI level 2 messages of essential information previously transmitted in the interior art by OSI level 3 messages between mobile station and external IP agent. The method, which is the subject of the invention, is remarkable in that the deleted messages are in particular messages of the prior art represented in FIG. 1, such as the A.Sol message transmitted between the terminal mobile STA and the external IP agent FA, whether or not the latter is locally associated with a radio access point AP, the radio access devices of the prior art being constituted either by simple access points AP radio not associated locally with an external IP agent FA, or on the contrary by an access pair formed by an AP radio access point and an external IP agent FA associated locally, but for which the conventional protocol, as defined in FIG. relative to the prior art, is not modified, however the transmission of OSI level 3 messages is executed.

In addition to the agent solicitation message A.Sol, the agent information message A.Adv is also deleted, this message being none other than the response message of the external agent FA associated or not locally with the points. AP access, in the prior art, transmitted to the mobile station STA.

The aforementioned messages deleted from the prior art are defined below:

- A.Sol: This is an ICMP message for the Internet Contrai Message Protocol, sent by the broadcast mobile terminal to find an external IP agent FA in its IPv4 subnet. Such a message is then not necessary when the access pair {AP + FA} is available since, as soon as the mobile terminal STA associates with the access point AP, the external IP agent FA locally associated with the latter is immediately located. The agent solicitation message A.Sol is therefore removed.

- A.Adv: This message is also an ICMP message sent by the external IP agent broadcast in the aforementioned IPv4 subnet. In the case where each subnet consists of a single base station defined by the IEEE 802.11 Recommendation, the IPv4 subnet is a BSS subnet for the Basic Service Set in English, that is to say radio link, operated by an AP radio access point. The purpose of the agent intelligence message is to inform the machines, i.e. the mobile terminals that have connected to the IPv4 subnet of the presence of the external IP agent FA and to set them to provision of several temporary IP addresses, these addresses being designated CoA addresses for Care of Adress in English. The structure of the A.Adv agent information message is introduced below in Table I.

Table I

The essential fields for the STA mobile terminal are:

the router address RA: IPv4 address of the external IP agent FA, coded on 32 bits;

the maximum lifetime RLFT accepted by the external IP agent FA during the registration procedure, coded on 16 bits, designated Registration Life Time in English;

the list of temporary addresses designated [CoA] each CoA temporary address being coded on 32 bits.

The agent information message A.Adv can then be reduced to the three preceding essential fields and sent by an OSI level 2 message or frame after the search response message R_Rep, as previously described in the description. It is recalled that the aforementioned search response message is a broadcast message of the AP access point in a BSS, in the same way that the authentication success message A_S is a broadcast message of the external IP agent FA in its IPv4 subnet.

Preferably, the aforementioned information message P_A advantageously also has the maximum lifetime of the recording procedure accepted by the external IP agent FA and the list of new temporary addresses [CoA] available. This message is an OSI level 2 management frame in the format of the IEEE 802.11 standard shown in Table II below, among the combinations that remain free in Table III below.

In the above and following tables, the type and subtype descriptions are given according to the official nomenclature of the IEEE 802.11 standard.

Table II

BO B1 B2 B3 B4 B7 B8 B9 B10 B11 B12 B13 B14 B15

Protocol Type Sub-To More Retry Pwr More WEP Order Version Type DS DS Frag Mgt data

-4 * ~ 4 * ~ <I ^ A> - ^• 4 * ~ "^ <>-4> - ^• 4> • 4 * ~ 4 ^

Bits 2

The previous Table II represents the format of the control frame of the IEEE 802.11 standard.

Board

For example, the following reserved management value can be used:

- type: b2 b3 = 00,

- subtype: b4 b5 b6 b7 = 1101.

To include the values of the IPv4 subnet address of the access couple {AP + FA}, the maximum lifetime of the record and the list of provisional addresses [CoA], the format of the management identical to that of the P_Rep search response messages known from the prior art and illustrated in Table IV below.

Table IV

Bytes: 2 2 6 6 6 2 0-2312 4

Frame Sequence Frame Control Duration DA BSS ID Control Body FCS

MAC HEADER (MAC INPUT)

In the management format of the aforementioned frames, the Frame Control field designated "Frame Control" represents the format shown in Table II. The other formats are specific to the management frame.

Thus, the entire field designated Framebody for Frame Body in Table IV mentioned above is 0 to 2312 bytes to include the three fields of the information message P_A.

In addition, according to a remarkable aspect of the method that is the subject of the invention, the registration request message Reg_Req and the registration response message Reg_Rep make it possible to execute the transaction between the external agent FA and the agent HA. from the original site of the STA mobile terminal are built according to the UDP / IP protocol.

By way of non-limiting example, they may have the following format: - Registration Request message, Reg_Req: This is a Mobile IPv4 message built on the UDP / IP protocol. Encapsulation and illustrated by Table V below: Table V

I IP header I header I UDP header I Mobile IP header I header I I extensions

This message is created by the mobile terminal STA and directed to the agent of the original site HA so that the mobile terminal can register with the latter.

The fields of the registration request message Reg_Req are represented in table Vl below:

Table VI

The remarkable fields are:

- LFT for "Lifetime": lifetime of the 16-bit encoded record;

- On-premises address of the mobile terminal, H_ad for "Home address": IPv4 address on site of the mobile station that is to say that allocated by the agent of the origin site HA encoded on 32 bits;

- IPv4 address of the agent of the original HA site known by the mobile terminal STA and coded on 32 bits;

- Temporary address chosen by the CoA mobile terminal; IPv4 address chosen from the list of addresses by the external IP agent FA via the information message P_A and coded on 32 bits. The aforementioned fields can then be included in a management frame according to the IEEE 802.11 standard among the combinations which remain free as previously described in connection with Table III, and then be sent via the association registration request. or reassociation R_Reg without additional delay.

For example, the following management reserved values: - Type b2 b3 = 00, - Subtype b4 b5 b6 b7 = 1110.

The reassociation request and then the association registration message R_Req and R_Reg message containing the registration information are transmitted to the agent of the original site HA, that is to say that the four fields previously described included in the "Framebody" frame body of Table IV are transmitted by the R_Req message, which is immediately followed by the R_Reg registration request message without waiting for a DIFS and SIFS time specific to the MAC layer of the IEEE 802.11 standard. . The aforementioned messages are then preferably transmitted glued to each other to reduce connection time or connection transfer.

At the chosen access couple {AP + FA}, the registration request message R_Req is then generated from the information of the R_Reg message association registration or reassociation request according to the structure described in connection with the table. Vl previously mentioned.

With reference to the above-mentioned table V1, it is recalled that the latter includes an important field, the identification ID field consisting of a number created by the access pair {AP + FA}, this field making it possible to match according to a one-to-one relationship. on the one hand, the registration request R_Reg and, on the other hand, the registration response Reg_Rep. This makes it possible to guard against risks of untimely attacks. For example, the identification number ID shown in Table VI is advantageously coded su 24 bits:

The registration response, Reg_Rep: This response is a message sent by the agent of the originating site HA of the mobile terminal STA to indicate whether a record is valid or not. In the MIPv4 protocol, this message is received by the external IP agent FA, which updates its data tables and retransmits the latter to the mobile terminal STA. The only useful information of this message is the validity or invalidity of the registration.

In order to reduce the connection time or connection transfer, in accordance with the method of the invention, the access pair {AP + FA}, as soon as it receives the aforementioned message, checks whether the recording is valid or not. Based on this verification information, upon positive verification, the external IP agent FA of the aforementioned access pair conditionally transmits the reassociation response message R_Rep indicating the success or failure of the reassociation. Under these conditions, by associating a single frame at OSI level 2 constituting the reassociation response message, a connection or a connection transfer is validated or not.

In the event that there has been connection failure or reconnection, the mobile terminal STA can then attempt a new registration by returning two messages, in particular a reassociation request R_Req and an association registration request R_Reg, and as previously described in connection with Figure 2.

The operating mode of the method which is the subject of the present invention, as described above with reference to FIG. 2, makes it possible to obtain the following advantages:

- connection time or overall connection transfer L ₂ + L3 reduced;

- reduction of the number of messages sent on the radio link because it actually removes the OSI level 3 message A.Sol message and A.Adv between mobile terminal and external IP agent FA;

- the size of the transmitted messages is reduced because the essential messages are integrated at level 2 OSI, the messages A.Adv and the message of the registration request are replaced by the message P_A and by the association registration request R_Reg respectively.

The method that is the subject of the present invention requires the implementation of few changes with respect to the process of the prior art: - need for a single access pair {AP + FA} this type of equipment already existing in addition already on the market ;

- the current messages from the IEEE 802.11 standard remain the same while the protocol itself is little changed;

- addition of P_A and R_Reg association or reassociation registration messages;

- adaptation of the mobile terminal and the access couple {AP + FA} which must be able to interpret the above-mentioned messages, these modifications being the subject of a more detailed description later in the description; maintaining the transactions between the external IP agent FA and the agent of the original site HA;

maintaining the compatibility of any communication card according to the IEEE 802.11 standard with the method that is the subject of the present invention, any mobile terminal equipped with such a conventional card being able to continue to communicate normally with an access pair {AP + FA} allowing the implementation of the method of the present invention;

- any access couple {AP + FA} of the prior art existing on the market, and by definition not compatible with the subject of the invention, can however communicate with any IEEE 802.11 card fitted to a mobile station and allowing the implementation of the method object of the previous invention.

A more detailed description of a preferred mode of implementation of the method, object of the present invention, will now be given with reference to FIG.

The aforementioned preferred embodiment makes it possible to trigger the recording of a mobile terminal STA from its original site agent HA just after the authentication of the mobile terminal, in the case where each IPv4 subnet consists of a single WiFi access point. Thus, the recording is anticipated and performed in parallel at the end of the level 2 connection or the level 2 connection transfer, that is to say the reassociation with a new access point AP of a separate access couple. By anticipating the transmission of the request message recording the external IP agent of the selected access couple to the agent of the mobile terminal's original site, prior to the transmission by the mobile terminal of the Re-association request R_Req, as shown in Figure 3, this allows to conduct in parallel the connection registration operation with the HA agent of the original site of the mobile terminal STA and the reassociation operation conducted between the mobile terminal STA and the access point AP radio of the chosen access couple {AP + FA}.

In FIG. 3, the authentication procedure used in this embodiment can, in a non-limitative manner, be constituted by the WEP procedure for Wire Equivalent Privacy in English. This is a specific operating mode for authenticating the mobile terminal STA. Other authentication procedures may be implemented in a non-limiting manner.

In the case of the WEP procedure, this procedure requires the sending of four messages, an authentication request message A_R transmitted from the mobile terminal STA to the selected access couple {AP + FA}, the registration message of association or reassociation R_Reg then being transmitted immediately after the authentication request A_R.

The access pair {AP + FA} responds to the mobile terminal by transmitting an authentication challenge message A_C to the mobile terminal STA and the latter performing the necessary cryptographic calculations transmits to the chosen access couple {AP + FA} an authentication response message A_Rep, which allows the aforementioned access torque to verify the authentication calculation performed by the mobile terminal STA. Upon verification of the true value of the aforementioned authentication calculation, the access pair {AP + FA} can then proceed with the transmission of the registration request message RegJReq to the agent of the home site HA of the STA mobile terminal, this transmission can then be made conditional on the successful authentication procedure of the mobile terminal STA near the radio access point AP and the access couple {AP + FA}.

In addition, and substantially simultaneously with the transmission of the registration request Reg_Req, the method which is the subject of the invention, implemented as represented in FIG. 3, then consists in transmitting, of the chosen access couple (AP + FA}, an authentication success message

A_S to the mobile terminal STA.

Under these conditions, and in order to optimize the anticipation of the transmission of the aforementioned registration request message, the method in the embodiment of FIG. 3 in accordance with the subject of the invention consists of transmitting the reassociation registration message R_Req from the mobile terminal STA to the radio access point AP of the selected access pair {AP + FA} as soon as the successful authentication procedure is started.

It is understood, in particular, that to anticipate the registration of the connection of the mobile terminal STA to the agent of the original site HA of this terminal, it is necessary that the mobile terminal transmits to the external agent IP the parameters of the terminal. registration as soon as possible. Thus, it is necessary to anticipate sending the Reg_Req association registration or reassociation message.

This message is therefore transmitted just after the authentication request message A_R without waiting for a time DIFS or SIFS, time specific to the CSMA / CD of the IEEE 802.11 standard. Advantageously, the two messages A_R authentication request and registration request R_Reg are then pasted together to reduce connection time or connection transfer.

The access pair {AP + FA}, after receiving the two aforementioned messages, then begins to prepare a registration request message that is to say the message Reg_Req, MIPv4 type message, but does not transmit the latter to the original site agent HA of the mobϋe terminal

STA only when the authentication procedure of the latter, vis-à-vis the chosen access couple {AP + FA}, is successful.

By way of non-limiting example, when the authentication procedure is a conventional WEP procedure, upon receipt of the authentication response message A_Rep, the selected access pair {AP + FA} verifies the identity of the mobile terminal and sends the registration request Reg_Req immediately afterwards. The mobile terminal STA receives the authentication success message A_S and then transmits in response the reassociation request R_Req to the radio access point AP of the chosen access pair {AP + FA}.

Meanwhile, the originating site agent HA of the terminal STA receives the registration request Reg_Req and transmits the registration response message Reg_Rep back. Upon receipt of the latter by the selected access couple {AP + FA}, the latter transmits the association or reassociation response message R_Rep which terminates the connection procedure or global connection transfer. The mode of implementation of the method which is the subject of the invention in a preferential manner as illustrated in FIG. 3 makes it possible to obtain a connection or global connection transfer time designated L ₂ + L ₃ transfer which is further reduced. Indeed, the registration request message R_Reg is sent during authentication so that the registration with the originating site HA of the requesting mobile terminal STA is executed as soon as the aforementioned mobile terminal is authenticated. It is understood, of course, that the recording can not be started before a successful authentication.

In parallel with the registration, the authentication procedure is then completed and the reassociation procedure is started, which of course makes it possible to reduce the total time involved.

The modifications necessary for the implementation of the method that is the subject of the invention according to the preferred embodiment of FIG. 3 then require the following changes in the architecture of the prior art:

at the mobile terminal STA, the association registration or reassociation message R_Reg is sent immediately after the message authentication request transmission A_R;

- At the chosen access couple {AP + FA}, upon receipt of the aforementioned R_Reg message, the registration request message Reg_Req must be created but transmitted only after verification of the identity of the mobile terminal STA;

the other changes brought into play with respect to the architecture of the prior art are the same as those necessary for the implementation of the first embodiment illustrated in connection with FIG.

A more detailed description of an access torque to an IP network from a mobile terminal over a radio link, in accordance with the subject of the present invention, will now be given in connection with FIG. 4.

As mentioned previously in the description, the access pair {AP + FA} object of the invention comprises an AP radio access point and an external IP agent FA, locally associated with the aforementioned radio access point. It is furthermore remarkable that, in addition to an I / O input / output device connected to the IP network and a CPU, to which a RAM memory is associated, it comprises at least one module M1 for creating and transmitting to any requesting mobile terminal an intelligence message such as the P_A message previously described in the description with FIGS. 2 and 3.

It is recalled that this information message comprises at least the IP address of the external IP agent FA constituting the access pair {AP + FA} chosen.

Furthermore, as shown in FIG. 4, it also comprises a management module for inhibiting the transmission by the radio access point of the radio access torque AP of the access pair {AP + FA} of any message of association response to a requesting mobile terminal and, therefore, inhibition by any requesting mobile terminal of the transmission of any OSI level 3 message to any external IP agent, such as the external IP agent FA locally associated with the point AP radio access forming the access couple {AP + FA} considered.

It is understood, in particular, that the access couple comprises well heard a transceiver and a radiating element according to the WiFi standard, for example, which can be driven advantageously from the central processing unit CPU RAM working memory and of course modules M1 and M2 above. Furthermore, as shown in the same FIG. 4, the access torque object of the invention advantageously comprises a module M3 for creating and transmitting the external IP agent FA of the access pair {AP + FA} to the originating site agent HA of the requesting mobile terminal STA of a registration request message the message Reg_Req. Finally, an M4 module is provided, this module executing the creation and transmission of the external IP agent to the requesting mobile terminal STA of an association response message, that is to say the R_Rep message represented in FIG. 2 or in FIG. 3. The reassociation concerns the AP access radio access point AP (AP + FA) and the requesting mobile terminal STA. It will of course be understood that the transmission of the aforementioned message is carried out via the transceiver T / R and the radiating element of the access point AP.

As regards the implementation of the aforementioned access torque, it is indicated that the modules M1, M2, M3 and M4 advantageously consist of separate software modules integrated into a common software.

In a nonlimiting preferred embodiment, the access torque object of the invention may be equipped with a nonvolatile programmable memory for example, denoted PM, which is intended to receive the modules M1, M2, M3 and M4.

The use of a nonvolatile programmable memory appears useful insofar as the aforementioned software modules can be downloaded directly on each access pair {AP + FA} considered for updating, updating, or even changing a couple of d access {AP + FA} of the prior art in which the only update software and aforementioned modules constituting the latter then allows the transition from a conventional connection or reconnection process to a connection method or connection transfer according to the object of the present invention.

A more detailed description of a use of the connection method that is the subject of the present invention, as described above, and of the use of an access torque to an IP network from a mobile terminal by radio link, as described above with reference to FIG. 4, will now be given in connection with FIG. 5a and then FIG. 5b.

With reference to FIG. 5a, it is indicated that the access torque is formed by an ADSL modem constituting the external IP agent with which an AP radio access point is associated. Each radio access point is associated with a separate IP subnet. This allows a mobile terminal STA, during roaming, to connect successively to one or other of the distinct IP subnets with an optimized connection time or connection transfer. Under these conditions, each ADSL modem as shown in FIG. 5a, is connected to the INTERNET network for example via a device to a DSLAM module for DSL Access Modul in English and to a designated broadband access server. BAS for Broadband Access Server, all managed by a DHCP server for Dynamic Host Configuration Protocol in English.

Another use of the connection method, which is the subject of the invention as described with reference to FIGS. 2 and 3, and of a pair of accesses to an IP network from a mobile terminal by radio link conforming to FIG. The subject of the present invention, as described with reference to FIG. 4, will now be described with reference to FIG. 5b.

In the above-mentioned figure, the access pair is formed by a router RO connected to a LAN of the LAN corporate network type and to the INTERNET for example by a plurality of radio access points denoted AP1, AP2, to APn. Each aforementioned radio access point corresponds to a separate subnet! P. This allows a mobile terminal STA to connect successively to one or the other of the distinct IP subnetworks with an optimized connection and connection transfer time as described. previously in the description.

The present invention finally relates to a computer program product recorded on a storage medium for execution by a computer or by a dedicated device comprising at least one central processing unit.

The computer program product is remarkable in that it comprises a sequence of instructions for executing the method that is the subject of the invention as described above with FIG. 2 or FIG.

In addition, the aforementioned computer program product is also remarkable in that it is stored in modular form, for example in the form of modules M1, M2, M3 and M4 in a support integrated in an access couple (AP + FA} as previously described in connection with Figure 4.

Claims

A method of connection between a mobile terminal and an IP subnet via a radio access point, wherein said mobile terminal enters into communication with, on the one hand, this radio access point by via OSI level 2 messages, and on the other hand with an external IP agent via OSI level 3 messages, characterized in that, each radio access point being locally associated with an agent External IP to form an access pair, following the execution of a radio access point search step by said mobile terminal in which said radio access point of each access pair transmits to said mobile terminal a search response message, said method comprises at least:

the transmission of each access torque to the mobile terminal of an intelligence message, comprising at least the IP address of said external IP agent of the access pair; and, following a decision process of choice of access point access couple by said mobile terminal and a successful and committed authentication procedure between said mobile terminal and the radio access point of the couple d chosen access,

inhibiting transmission by said radio access point of the selected access torque of any association response message to said mobile terminal, and by said mobile terminal of any OSI level 3 message to an external IP agent ; and,

the selective transmission of said mobile terminal to said access point of said access couple chosen from an association request and an association registration request, said association registration request containing the information of a connection request; registering the mobile terminal with the home site agent of said mobile terminal; and,

the transmission of said external IP agent of said selected access couple to the agent of the originating site of said mobile terminal, to which a temporary address has been assigned, of a registration request message; and upon receipt of a registration reply message from said originating site agent of said mobile terminal by said external IP agent, - transmitting, from said external IP agent to said mobile terminal, a response message of association between said radio access point of said selected access torque and said mobile terminal, which makes it possible to optimize the total connection time by eliminating the transmission and response delay of any message at OSI level 3 to an agent External IP.

2. Method according to claim 1, characterized in that, in addition to the IP address of said external IP agent, said intelligence message furthermore comprises:

the maximum lifetime of the registration procedure accepted by said external IP agent;

- the list of new temporary addresses.

3. Method according to claim 1 or 2, characterized in that said intelligence message is formed by an OSI level 2 frame.

The method of claim 1 to 3, characterized in that said registration request message and said registration response message are constructed in accordance with the UDP / IP protocol.

5. Method according to claim 4, characterized in that the registration request message comprises at least:

a data field representing the life time of the recording;

a field representing the IP address of the mobile terminal on its original site, allocated by said agent of the site of origin of said mobile terminal; a field representing the temporary IP address chosen by the mobile terminal from the list of temporary audiences transmitted by the external IP agent, via the intelligence message; an identification field comprising an identification code generated by the access pair, said identification code enabling the one-to-one correspondence between said registration request message and said registration response message.

6. Method according to one of claims 1 to 5, characterized in that the transmission of said reassociation response message is conditional on the verification, by said access couple, validity of said record response message and registering the connection of said mobile terminal to said radio access point with said agent of the originating site of said mobile terminal.

7. Method according to one of the preceding claims, characterized in that it consists in anticipating the transmission of said registration request message of the external IP agent of said selected access couple to said agent of the original site. of the mobile terminal prior to the transmission, by said mobile terminal, said re-association request, which allows to conduct in parallel the connection registration operation with the agent of the site of origin of said mobile terminal and the reassociation operation conducted between said mobile terminal and said radio access point of said selected access couple.

8. Method according to claim 7, characterized in that the transmission of said registration request message is conditional on the successful authentication procedure of said mobile terminal with said radio access point.

9. Method according to one of claims 7 or 8, characterized in that, in order to optimize the anticipation of the transmission of said registration request message, it consists in transmitting said registration message of reassociation of said mobile terminal to said radio access point of said access pair as soon as said procedure is initiated successful authentication.

A pair of accesses to an IP network from a mobile terminal over a radio link, said access pair comprising a radio access point and an external IP agent locally associated with said radio access point, characterized in that said access pair, in addition to an input / output member connected to the IP network, and a central processing unit, and a creation and transmission module to any mobile terminal requesting an intelligence message, comprising at least the IP address of said external IP agent, includes at least: a management module for inhibiting transmission by said radio access point of said access couple of any association response message to a mobile terminal, and, in Consequently, any requesting mobile terminal will inhibit the transmission of any OSI level 3 message to any external IP agent, in particular to the external IP agent associated locally with said radio access point forming said access pair.

11. An access couple according to claim 10, characterized in that it further includes: a module for creating and transmitting said external IP agent of said access torque to the agent of the site of origin of said terminal mobile requesting a registration request message; and

a module for creating and transmitting said external IP agent to the mobile terminal of an association response message between said radio access point of said access couple and said requesting mobile terminal.

12. Use of the connection method according to one of claims 1 to 9 and a pair of access to an IP network from a mobile terminal by radio link, according to one of claims 10 or 11, in the access pair is formed by an ADSL modem constituting said external IP agent which is associated with a radio access point, each radio access point being associated with a distinct IP subnet, thereby a mobile terminal to successively connect to one or the other of said distinct IP subnetworks, with an optimized connection and connection transfer time.

13. Use of the connection method according to one of claims 1 to 9 and a pair of access to an IP network from a mobile terminal by radio link, according to one of claims 10 or 11, in which the access pair is formed by: a router connected to a LAN; a plurality of radio access points, each radio access point corresponding to a distinct IP subnetwork, which allows a mobile terminal to connect successively to one or the other of said distinct IP subnetworks , with optimized connection and connection transfer time.

14. Computer program product recorded on a storage medium for execution by a computer, or by a dedicated device comprising at least one central processing unit, characterized in that said computer program product comprises a sequence of instructions for carrying out the method according to one of claims 1 to 9.

15. Computer program product, characterized in that it is registered in modular form in a support integrated in an access couple according to one of claims 10 or 11.