Method of creation of a new communication network by a wireless terminal and terminal implementing the method

ES 2 393 152 T3

DESCRIPTION

Method for creating a new communication network using a wireless terminal and terminal that implements the method

The invention deals with a method for the creation of a new network by a terminal, more specifically when the terminal was initially associated with an existing network. The invention also deals with the terminal itself. It is particularly applicable in the context of centrally controlled wireless networks, although it is not limited to this context.

A centralized wireless communication network of the HIPERLAN 2 type has limited resources. When a large number of terminals are associated with the network, some terminals may be unable to reserve the resources required for their applications.

The document “ETSI TS 101 761-4 V1.4.1A (2002-5) BRAN HIPERLAN Type 2, Data Link Control (DLC) Layer; Part 4: Extension For Home Environment, section 6.7.1 “Dymanic Central Controller Selection / Principle” ”describes that a wireless terminal that is capable of becoming the central controller, and for which an attempt to associate with a central controller of a existing network fails, it attempts to become the central controller by initiating the central control selection process described in the above-mentioned document.

The document HABETHA J ET AL: “Central controller handover procedure for ETSI-BRAN Hiperlan / 2 Ad Hoc network and clustering with quality of services guarantees” describes the transfer of control from a central controller to another device in a Hiperlan / 2 network. Under certain circumstances the central controller chooses one of the connected terminals to replace itself in the control. It transmits some management information to the future controller, then the network is stopped and the new one is started under the control of a new controller.

The invention deals with a method for creating a new communications network by means of a wireless terminal, the method of which is characterized in that, initially the wireless terminal is part of an existing centralized network that includes an access point capable of controlling the association of terminals to this network, includes, for the associated terminal, the steps of:

dis-association of the terminal from the network; and initiating a procedure for creating a new network including a declaration of the terminal as an access point of the new network, wherein the operational parameters of the new network are such that communications on the new network do not interfere with the existing network.

Thus, a terminal previously associated with the network, but disassociated from this network, can create a new network, without interfering with the initial network. The new resources are this way.

According to a preferred embodiment, the terminal takes the initiative of the de-association The terminal can decide in this de-association if for example the access point of the initial network does not respond favorably to certain requests, for example in reference to the provision of existing network resources.

Other characteristics and advantages of the invention will become apparent through the description of a non-limiting exemplary embodiment, explained by reference to the accompanying drawings, in which:

Figure 1 is a diagram showing the information exchanges between the terminal and the access point in the event of dis-association after association;

Figure 2 is a diagram of the same type as that of Figure 1 in the case of a denial of the start of a frequency change by the access point;

Figure 3 is a diagram of the same type as that of Figure 1 in the case of a denial of connection establishment;

Figure 4 is a flow chart of the method according to the example embodiment.

The example embodiment fits within the context of a HIPERLAN 2 communication network. HIPERLAN 2 is a standard under development by ETSI (European Telecommunication Standard Institute). In this type of network in which communication takes place using radio waves of approximately 5 Ghz, a unit called an Access Point (AP) or Central Controller (CC) manages the access of other network devices to the transmission medium. These other devices are called wireless terminals or Mobile Terminals (MTs). To be able to access the network, a wireless terminal

ES 2 393 152 T3 must first associate with the access point. The proper procedure is described in particular in the following document:

“ETSI TS 101 761-2 V.1.4.1A (2002-05) Broadband Radio Access Networks (BRAN); HIPERLAN Type 2: Data Link Control (DLC) Layer; Part 2: Radio Link Control (RLC) Sublayer ”, and in particular Section 5.1“ Services supporting ACF (Association Control Function) ”.

According to the present example embodiment, there may be various reasons for non-association of a wireless terminal to the access point, or a disassociation of an associated wireless terminal.

Figure 1 is a diagram of a network having an access point AP-CC and a wireless terminal MT. Other wireless terminals on the network are not displayed. A typical wireless terminal has an interface with the communications medium (the wireless network) and a microprocessor that executes appropriate applications and protocols, the code for this being stored in a memory within the terminal. The diagram in Figure 1 indicates the information exchanged between the two devices during an attempt to associate the wireless terminal MT to the access point AP / CC. The wireless terminal, once activated, analyzes the radio activity to detect the presence of a network that has characteristics that allow an association a priori. These characteristics include in particular the identity of the network and are disseminated in the data set controlled by the access point.

The terminal starts a dialogue with the access point to exchange parameters such as the list of supported convergence layers and when a wireless terminal can transmit in direct mode to another wireless terminal. In Figure 1, the association is assumed to take place. Later, with the associated mobile terminal, the access point can arbitrarily decide to disassociate this terminal.

Furthermore, a mobile terminal associated with an access point can be disturbed by another device on another network using the same frequency. In this case, the wireless terminal may request the access point to which it is associated to make a change to the network frequency. This process is known as DFS (Dynamic Frequency Selection). The access point may however reject the frequency change, and the wireless terminal may then disassociate itself. The wireless terminal can also disassociate itself if the access point has not responded to the DFS request in a predetermined time. This scenario is illustrated in Figure 2.

Figure 3 represents the network in the state in which the wireless terminal is associated with the access point. The wireless terminal sends a connection establishment request to the access point. The latter can reject the request, notifying the wireless terminal of the rejection. This can happen if the level of traffic on the network is significant. In accordance with the present example embodiment, an application of the mobile terminal then decides to disassociate itself from the network, at least for some connection types. According to the present embodiment, this disassociation is initiated only if there is no other connection in the network involving the mobile terminal in question.

Figure 4 is a flow chart of the method according to the present example embodiment. In response to a rejection of a request, such as (for example) establishing a connection or changing the frequency, the wireless terminal disassociates itself from the existing network. In the other two cases that have been described, the wireless terminal is already disassociated (in the examples mentioned, both in response to a decision of the access point, and in response to a rejection of association by the access point).

The disassociated handset shows itself as an access point of a new network.

When possible, it will advantageously use a frequency that is different from that of the initial network in order to avoid any interference. If the new network is created in response to a frequency change rejection, then the new network will advantageously use a frequency that is different from the frequencies of the initial network and the interfering network. At this end, the mobile terminal can start the central controller selection process mentioned in the introduction.

The new access point cannot a priori announce its new status to the terminals already associated. It is the task of another terminal, once disassociated, to find a new access point and associate with it.

According to one embodiment, several terminals of the same existing network may decide to disassociate from the existing network to create their own network. These terminals then begin a selection process to determine which of these terminals will be the access point of the new network. The elements to make the disassociation decision can be communicated between the devices over the existing network. Therefore, the new network allows avoiding the saturation of some resources of the initial network, operating on another frequency.