FR2873250A1 - METHOD FOR CONNECTING A RADIO COMMUNICATION TERMINAL TO A NETWORK AMONG AT LEAST TWO ACCESSIBLE NETWORKS, TERMINAL AND CORRESPONDING BASE STATION - Google Patents

Abstract

The invention relates to a method of connecting a radiocommunication terminal to a communication network from among at least two accessible communication networks, including a first network, called the main network, and at least a second network, called the secondary network, said network. main implementing at least one main communication channel and one signaling channel. According to the invention, said signaling channel carries service accessibility information in said secondary network or networks, and said terminal reads said accessibility information , in a standby mode, and connects directly to one of said secondary networks, without going into connected mode on said main network, if said accessibility information indicates that a connection to said secondary network is possible.

Description

A method of connecting a radiocommunication terminal to a network among

  at least two accessible networks, terminal and corresponding base station.

  FIELD OF THE INVENTION The field of the invention is that of digital radiocommunications.

  More specifically, the invention relates to access to different services, for example the Internet, digital video, voice transmission and / or multimedia data at the rate, ..., for a user equipped with a radiocommunication terminal, when the user is located in a coverage area common to several different technology networks.

  Such networks are for example of the type: - digital telecommunications, for example Universal Mobile Telecommunications Service (UMTS), GSM (Global System for Mobile Communications for global mobile communications system), GPRS (General Packet Radio Service) for general packet radio system) or EDGE (Enhanced Data for GSM Evolution, for Advanced GSM); - television or digital radio, for example DVB-H (Digital Video Broadcasting - Handhelds for portable digital television system); - wireless computer networks, such as Wireless Local Area Network (WLAN), or Wireless Wide Area Network (WWAN).

  More specifically, the invention relates to optimizing the connection to one of these networks, said secondary network, separate from a so-called main network, which connects by default the terminal in standby mode.

  The main network implemented can, for example, be of UMTS type.

  2. Solutions of the Prior Art A technique enabling a communication terminal to connect to a second network is already known and specified in the UMTS standard.

  According to this technique, a user of a terminal, located in a coverage area common to a UMTS-type main network, and at least one secondary network, can access a service of the secondary network by first connecting to the network. primary, then to the secondary network.

  This connection technique is particularly presented in relation with FIGS. 1A, 1B and 1C.

  During a first step 21, a terminal 11 located in a coverage area common to the UMTS network and to another network, for example the GSM network, is in idle mode, also called idle mode.

  It is then registered in a group of users, also called paging group, or paging 12 (of the English Paging Group), when it is located in a cell of the UMTS network.

  Note that, without communication, the terminals 11, 112, 113 of a group of users 12 are in standby mode, that is to say in a mode where they are not in connected mode, but present and available for a communication in the cell of the UMTS network. These terminals are in particular listening for signals transmitted by a base station belonging to this cell.

  These signals are emitted on: common transport channels corresponding to the services offered to the upper layers of the communication protocol, in particular on BCH (or Broadcast CHannel broadcast channel) and PCH (or search channel) channel. mobile English Paging CHannel); and common transport channels corresponding to the physical layer of the communication protocol, in particular on CPICH channels (or common pilot channel of the English Common Plot CHannel).

  These channels, used by 3GPP networks, are well known to those skilled in the field of mobile networks and are in particular specified in the 3rd Generation Partnership Project standard; Technical Specification Group Radio Access Network; 1999-2002 Reference: 3GPP TS25.211 Physical Channels and Mapping of Transporters on Physical Channels (FDD). These channels are therefore not described further.

  During this first step 21, each user group 12 is associated with an indicator, called call indicator, carried by the physical channel PICH (of the English Paging Indicator CHannel, for call indicator channel). PICH channel periodically sending information to the PCH channel.

  FIG. 2 shows the structure of a radio frame on the PICH channel of the UMTS network.

  Such a PICH frame comprises 300 bits, and has a length of 10 ms. On the 300 bits of a frame, 288 bits are used to carry call indicators (also called paging indicators). The remaining 12 bits are not used and are not transmitted.

  These call indicators are intended in particular for a group of users 12 to indicate that a message is intended for a user 1 l of the group 12.

  As illustrated in FIGS. 1A, 1B and 1C, while the terminal 11 is still in standby mode, this message (Paging Typel) is sent on the S-CCPCH (English Secondary Common Control Physical CHANNEL) channel where the PCH channel to request the user to establish a signaling connection with the main network, in a second step 22.

  It is recalled that the PCH channel carries a message including the user identifier (in English TMSI for Temporary Mobile Station Identity) and the cause of call (English PagingCause).

  On receipt of this message, the terminal 11 of the user concerned starts the signaling connection establishment procedure, and switches from idle mode to a mode connected to the main network.

  During a third step 23, the terminal checks the radio resources available on the main network (RRC Radio Resource Control English), and allocates resources according to availability (allocation of RAB, English Radio Access Bearer).

  If the allocation of radio resources fails, ie if the UMTS main network does not have sufficient resources, it is considered that the requested service can not be offered, and the connection is rejected.

  The terminal 11, while remaining in connected mode, is then redirected to another UMTS cell, during a cell reselection procedure, or to another network, during a transfer procedure 24, called handover.

  Thus, according to this technique of the prior art, we go from a sleep mode to a connected mode before checking the availability of resources.

  For the exchange protocol presented in FIG. 1C, the terminal 11 is under voltage.

  It is considered that it has previously performed a registration procedure, and that it is in a location area of the Mobile Public Land Nominal Network (HPLMN).

  The switch MSC / VLR (mobile switching center / visitor location register for mobile service switch / visitor location recorder) then requests the broadcast of a paging message (including the temporary identity of the terminal TMSI), by the radio network controller (RNC) or RNC (s) in the different cells of the terminal location area 11.

  The identified terminal then establishes the RRC connection, the Paging response message is routed to the MSC / VLR. The terminal 11 is then authenticated and the required resources are allocated.

  3. Disadvantages of the Prior Art The connection technique presented allows a terminal to switch from a primary network to a secondary network providing a desired service.

  This technique, implemented when the desired service is not supported by the main network, or when the main network does not have sufficient resources, has several disadvantages.

  A first disadvantage of this technique is that it requires the use of resources of the main network while the service requested by the user is not supported by the main network, but by a secondary network.

  Thus, if a user requires a service, for example a digital video, passing through the DVB network and not by the UMTS main network, obtaining the video requires prior switching to connected mode with the main network, even if the Radio resources needed for this connection are not available in the main network, while they are available in the DVB network.

  There is therefore a risk of refusal of service, while resources are available.

  Another major drawback of this technique of the prior art is that, in the case where the service or the resources are not available on the UMTS network, it requires a large number of operations: listening to the PICH channel; - the establishment of a signaling connection; - the transition from a standby mode to a connected mode; - verification of the availability of resources; - the exchange of messages to select a new cell, or a new network; - switching to the desired and / or available network.

  Thus, this technique of the prior art requires many exchanges, which are expensive in time and resources.

  4. OBJECTIVES OF THE INVENTION The object of the invention is notably to overcome these disadvantages of the prior art.

  More specifically, an object of the invention is to provide a technique that allows a user to simply and efficiently access a secondary network, even when the main network resources are not available, and / or when a desired service by the user is not available on the main network.

  Another objective of the invention is to propose such a technique that simplifies and optimizes the mode changes from the standby mode to the connected mode, and vice versa, on the different networks.

  The invention also aims to provide such a technique does not require the addition of additional messages, for example relating to the requested service.

  In particular, an objective of the invention is to propose such a technique that makes it possible to optimize the allocation of radio resources, and does not require the allocation of additional resources for the allocation of the service.

  Yet another object of the invention is to implement such a technique simply, efficiently and inexpensively.

  5. ESSENTIAL CHARACTERISTICS OF THE INVENTION These objectives, as well as others which will appear subsequently, are achieved by means of a method of connecting a radiocommunication terminal to a communication network among at least two networks. communication networks, including a first network, said main network, and at least one second network, said secondary network, the main network implementing at least one main communication channel and a signaling channel.

  According to the invention, the signaling channel carries service accessibility information in the secondary network (s). The terminal reads the service accessibility information, in a standby mode, and can connect directly to one of the secondary networks, without going into connected mode on said main network, if said accessibility information indicates that an audit connection secondary network is possible.

  Here, and in the remainder of the document, is meant by accessibility to the service the existence of the service and / or the availability of the resources necessary for the connection.

  Thus, the service accessibility information transmitted over the signaling channel makes it possible to indicate either that the service is available on the secondary network and that the resources necessary for the connection with the secondary network are available, or that the service is available. on the secondary network, without any information on the availability of resources.

  Thus, the invention is based on a completely new and inventive approach of connecting a terminal to a secondary communication network, not requiring to go into connected mode on the main network to then be able to switch to the secondary network. selected.

  The invention thus optimizes the allocation of radio resources, and allows a user to connect directly to a secondary network, even if the main network does not have available radio resources.

  According to the invention, a channel of the main communication network carries information concerning service accessibility, that is to say the existence of a service and / or the availability of the resources necessary for connection to different networks. (or services) that a user may wish to access.

  Based on this accessibility information, the terminal can therefore connect directly to the secondary network providing such a service, without going into connected mode on the main network.

  Advantageously, the main network implements two signaling channels: a paging channel comprising, among others, signaling notification data, in the form of messages belonging to a predetermined message list; a paging indicator channel, returning to said paging channel, when signaling notification data is present for said terminal or for a group to which said terminal belongs, one of said messages indicating that service accessibility information is present for said terminal or for a group to which said terminal belongs.

  Such a paging channel thus makes it possible to broadcast control information to a terminal whose network does not know the location, by broadcasting the information in several cells.

  These two paging channels and paging indicators thus make it possible to identify a terminal present in a cell, belonging to a group of users, and to send it, to itself or to the group to which it belongs, a message concerning the information service accessibility, if the terminal (or the group to which it belongs) is affected by the message.

  Preferably, this accessibility information is carried by the paging indicator channel.

  Advantageously, this paging indicator channel is organized into frames having, in each of the frames, a first portion carrying paging indicators and a second portion carrying the service accessibility information.

  The pagination indicators, also called call indicators, are notably associated with a group of users present in a cell of the main network.

  The connection method according to the invention is notably remarkable in that it implements, in said terminal, the following steps: reading an indicator intended for said terminal, or the group to which it belongs, in one of said frames of said channel pagination indicators; storing said second portion of said frame; reading a message in said paging channel, according to said indicator; if said message is a message indicating that accessibility information is present, reading thereof in the second stored portion.

  Thus, according to the invention, the terminal located in the common coverage area of the different networks, in standby mode, stores the second part of the frame, including in particular the accessibility information, if one of the indicators of the indicator channel of pagination is the group of users to which the terminal belongs.

  Then, the terminal will read the paging channel to see if a message is addressed to it. If this is the case, he can decode the message.

  If the message specifies that accessibility information is present, the terminal can then switch to the secondary network, using the service accessibility information that the terminal has read on the paging indicator channel, and then stored .

  The terminal can thus go directly from the standby mode to the connected mode on the secondary network, presenting available resources, without going into connected mode on the main network.

  According to a preferred embodiment, each frame of the paging indicator channel comprises 300 bits, of which 12 for the second part.

  Thus, at least 3 of the 12 bits of the second part can be used to indicate the type of secondary network. It is thus possible to encode a GSM network with bits 001 ', a UMTS network with bits 100', a DVB-H network with bits '011' ...

  The remaining bits of the second part may in particular be used to define a carrier frequency of the secondary network, an identity of a communication cell of the secondary network, a type of service available on the secondary network or an available bandwidth information.

  According to this preferred embodiment, the main network is a UMTS type network, the paging channel is the PCH channel and the paging indicator channel is the PICH channel.

  Thus, the second part of each frame of the paging indicator channel corresponds to the unused 12 bits of the PICH channel in the UMTS standard.

  According to this embodiment, the message indicating the presence of the accessibility information corresponds to the spare part of the PagingCause message transported by said PCH channel.

  These different terms spare and PagingCause are defined in the UMTS standard and are well known to those skilled in the art. They are not defined further here.

  Secondary networks belong especially to the group comprising networks of the type: - wireless computer networks (WLAN, WWAN, ...); television or digital radio (DVB-H, ...); - Digital telecommunication (GSM, GPRS, EDGE,.) The invention also relates to a radiocommunication terminal implementing the connection method described above.

  According to the invention, the terminal comprises means for analyzing the accessibility information in standby mode in said main network, and connection means connected to one of said secondary networks, from said standby mode.

  The invention also relates to a radiocommunication system in a main network implementing said connection method described above.

  According to the invention, the system implements a step of inserting the accessibility data into said signaling channel.

  6. List of Figures Other features and advantages of the invention will appear more clearly on reading the following description of a preferred embodiment, given as a simple illustrative and nonlimiting example, and the accompanying drawings, among others. which: FIGS. 1A, 1B, 1C and 2, already presented in connection with the prior art, show a technique of connection to a secondary network as specified in the UMTS standard; FIG. 3 illustrates a common coverage area in a multiple network system; FIG. 4 shows a technique of connection to a secondary network according to the invention; FIG. 5 illustrates the structure of a radio frame on a PICH channel according to the invention for exchanges between a terminal located in the common coverage area of FIG. 3 and a main network.

  7. DESCRIPTION OF AN EMBODIMENT OF THE INVENTION The general principle of the invention is based on a technique enabling a terminal to switch from a main network to a secondary network, the user being located in a coverage area common to these two networks, when the radio resources of the main network are not available, and / or when a service desired by the user is not available on the main network but available on a secondary network, by going directly to the secondary network.

  To do this, the invention proposes to analyze a paging indicator channel between the terminal and the main network, this channel including service accessibility information relating to the existence of a service and / or the availability of the resources needed for the connection.

  This information thus makes it possible to identify the secondary network to which the user must connect in order to benefit from the requested service, without having to switch to connected mode with the main network.

  As illustrated in FIG. 3, the invention applies in particular in the case where the user (or his terminal) 11: is in the common multi-network coverage area; - is implemented on a main network; and when the desired application (or service) can not be offered by the backbone.

  These networks are for example of the DVB, UMTS, WLAN / WWAN or GSM / GPRS / EDGE type.

  The terminal 11 is then registered in a group of users of the main network. Such a user group is already described, in connection with FIGS. 1A, 1B and 1C.

  As illustrated in FIG. 4, this terminal 11 is listening for signals transmitted by a base station of the main network, and in particular listening to a paging channel and a paging indicator channel.

  This paging indicator channel includes paging indicators and accessibility information, and can be organized into successive frames.

  This service accessibility information specifies in particular the radio resource available on the different secondary networks.

  The terminal 11, listening to the signals transmitted by the base station in standby mode, can thus read accessibility information of the secondary networks present on the paging indicator channel.

  When the paging indicators relate to the user group to which the terminal 11 belongs, the terminal stores the accessibility information transported by the paging indicator channel.

  The paging channel carries a message comprising the identifier of a user and the cause of his request for service.

  When the message carried by the paging channel is addressed to the terminal 11, the latter decodes the message, while remaining in standby mode.

  If this message indicates that accessibility information is present, the terminal 11 switches from the main network to the secondary network offering the requested service.

  Thus, according to the invention, a terminal 11 can directly connect to a secondary network without going through the mode connected with the main network, in order to access a service offered by the secondary network.

  According to a preferred embodiment, the main network is considered to be of UMTS type, and the paging indicator channel used between the terminal and the main network corresponds to the PICH channel.

  Thus, with reference to FIG. 5, the new structure of such a radio frame on the PICH channel is presented.

  It is recalled that each of the PICH frames comprises 300 bits, of which 288 are used to carry the call indicators and the remaining 12 bits are not used and are not transmitted.

  As previously described in connection with the prior art, 288 bits per frame are used to carry call indicators associated with a group of users.

  The remaining 12 bits, which were not used according to the techniques relating to the UMTS of the prior art, are used here, so as to prevent the user's terminal from going from sleep mode to connected mode with the network. main to change network. In this bit is inserted information relating to the type of network on which the terminal can switch.

  Thus, according to the invention, these 12 bits comprise accessibility information, relating to the type of available network, according to the desired service.

  For example, it is possible to use at least 3 bits of the remaining 12 bits of a PICH frame to indicate the type of network, by encoding the type of network: a GSM network would be encoded by bits 001 '; a UMTS network by bits '100'; a DVB-H network with bits 011 '; etc. It is understood that this set of codes is a simple example, and that other codes, as well as a different number of bits, can be used to indicate the type of network, depending on the desired application.

  The other remaining bits can for example be used to indicate the carrier frequency (via the radio frequency channel number ARFCN, Absolute Radio Frequency Channel Number), and / or the cell identity (Cell ID), and / or the type of service, or any other information.

  According to the invention, the remaining 12 bits of at least one of the frames transported by the PICH channel are then transmitted on this PICH channel, with the 288 bits of call indicators.

  Thus, the method of switching a main network to a secondary network according to the invention does not require to go into connected mode with the main network.

  Finally, according to the invention, the terminal 11 listens to the PICH channel during a first step, in standby mode. If the user group to which it belongs is concerned by a message, the terminal stores the last 12 bits of the frames conveyed by the PICH channel, and reads the PCH channel to know to whom the message is addressed.

  In fact, the PCH (Paging Channel) channel makes it possible to broadcast control information to a terminal whose network does not know the location, by broadcasting the information in several cells.

  If the message is intended for him, the terminal can decode the message, PagingCause type and coded on 3 bits according to the UMTS standard, corresponding to the request of the user, and classically carried by the PCH channel.

  If the PagingCause message specifies that resources are available to access the service requested by the terminal 11 on a secondary network (spare value), the user terminal switches to this new network (secondary network) using the stored accessibility information. on the last 12 bits of the PICH channel.

  Thus, according to the invention, the proposed technique makes it possible to overcome the transition in connected mode to switch to another network, and therefore the establishment of a signaling connection, in a simple and effective manner.

  The ability to remain in sleep mode also helps to avoid an excessive exchange of messages, or the addition of new messages, while optimizing radio resources.

  The technique used thus makes it possible to ensure interoperability and quality of service, and to optimize the allocation of radio resources, depending on the application requested, when several networks of different technology (UMTS, GSM / GPRS / EDGE, WLAN, WWAN, DVB-H ...) are superimposed.

  The invention is of course not limited to a UMTS type main network, and can be applied to any type of radio network. However, if the main network used is of UMTS type, the invention has the advantage of keeping the existing UMTS protocol interface.

Claims (14)

  1. A method of connecting a radiocommunication terminal to a communication network among at least two accessible communication networks, including a first network, said main network, and at least one second network, said secondary network, said main network implementing at least one main communication channel and one signaling channel, characterized in that said signaling channel carries service accessibility information in the at least one secondary network, and in that said terminal reads said accessibility information, in a standby mode, and connects directly to one of said secondary networks, without going into connected mode on said main network, if said accessibility information indicates that a connection to said secondary network is possible.   2. Connection method according to claim 1, characterized in that said main network implements two signaling channels: a paging channel comprising signaling notification data, in the form of messages belonging to a list of predetermined messages; ; a paging indicator channel, returning to said paging channel, when signaling notification data is present for said terminal or for a group to which said terminal belongs, one of said messages indicating that service accessibility information is present for said terminal or for said group to which the terminal belongs.   3. Connection method according to claim 2, characterized in that said accessibility information is carried by said paging indicator channel.   4. Connection method according to claim 3, characterized in that said paging indicator channel is organized into frames having, in each of said frames, a first portion carrying pagination indicators and a second part carrying said accessibility information. .   5. Connection method according to claim 4, characterized in that it comprises, in said terminal, the following steps: reading an indicator for said terminal, or the group to which said terminal belongs, in one of said frames of said channel; pagination indicators; storing said second portion of said frame; reading a message in said paging channel according to said indicator; if said message is a message indicating that accessibility information is present, reading thereof in the second stored portion.   6. Connection method according to any one of claims 4 and 5, characterized in that each of said frames comprises 300 bits, including 12 for said second part.   7. Connection method according to any one of claims 1 to 6, characterized in that said accessibility information belong to the group comprising: - a type of secondary network concerned; a carrier frequency of said secondary network; an identity of a communication cell of said secondary network; a type of service available on said secondary network.   8. Connection method according to claim 7, characterized in that said accessibility information comprises the type of the secondary network encoded on at least 3 bits.   9. The method of connection according to any one of claims 1 to 8, characterized in that said main network is a network type UMTS.   10. Connection method according to claims 2 and 9, characterized in that said paging channel is the PCH channel and said paging indicator channel is the PICH channel.   11. Connection method according to claim 10, characterized in that said message indicating the presence of the accessibility information corresponds to the spare part of the PagingCause message carried by said PCH channel.   12. Connection method according to any one of claims 1 to 11, characterized in that the said secondary network or networks belong to the group comprising networks of type: - wireless computer networks, such as WLAN, WWAN; - television or digital radio, such as DVB-H; - digital telecommunication, such as GSM, GPRS, EDGE.   15. Radiocommunication terminal implementing the connection method according to any one of claims 1 to 12, characterized in that it comprises means for analyzing said accessibility information in standby mode in said main network, and means for passing connected mode on one of said secondary networks, from said standby mode.   16. Radiocommunication system in a main network implementing said connection method according to any one of claims 1 to 12, characterized in that it implements a step of insertion of the accessibility data in said channel of signaling.