Short-range wireless networks with connectivity parameters

Abstract

A method for communication between a station (STA) and at least a first access point (APi) belonging to a short-range wireless network identified by a network identifier, said network comprising a plurality of access points, the method being performed by the station and comprising: - receiving (S2) from said first access point (APi) a message (BCNi) comprising a network identifier (SSID), an identifier of at least one second access point from a plurality of access points and a value of a connectivity parameter of said second access point; - selecting (S3) from a plurality of access points an access point to connect to depending on the received value of at least one connectivity parameter; - using the identifier to establish (S4) a connection with the access point thus selected.

Description

[Technical Field]

[0001] The present invention relates to the field of communication networks, and more particularly to the field of short-range wireless networks such as home or public Wi-Fi networks.

[0002] More particularly, the present invention relates to the connection of a device, called a station, to one access point of a short-range wireless network when the device is located in the coverage area of ​​multiple access points to the network. [Background technology]

[0003] One problem with short-range wireless networks relates to the selection by a station STA in a roaming situation of an access point APi of a BSS network to which to connect.

[0004] Such a BSS network is, for example, a home local area network (or LAN) with a gateway GW that interfaces this BSS network with a telecommunications carrier's access network. Such a gateway GW can be, for example, an ADSL (Asymmetric Digital Subscriber Line) router, a home gateway, an ONT (Optical Network Termination), etc.

[0005] In a typical roaming situation, a station receives several beacon messages periodically transmitted by access points. Such beacon messages are defined in normative documents referencing 802.11 published by the IEEE (Institute of Electrical and Electronics Engineers). As a result, the station determines the received signal strength indications (RSSIs) of signals transmitted by various access points APi. The station then selects the access point that transmitted the signal with the highest RSSI and / or the highest signal-to-noise ratio (SNR).

[0006] However, this selection of an access point to connect to based solely on RSSI is not satisfactory: in practice, access points have limited bandwidth resources such that when several stations connect to a given access point, the effective bit rate of the access point decreases accordingly, which would otherwise inevitably result in a decrease in the RSSI value.

[0007] Additionally, the link established between access points is most often a wireless link. However, for cost reasons, most access points typically only have a single Wi-Fi chipset capable of transmitting and receiving short-range radio signals. In that case, the access points are said to operate in half-duplex mode.

[0008] Therefore, in this case, an access point cannot simultaneously receive data transmitted by another access point or station and transmit data to another access point or station. Again, such an operating mode of the access point is not reflected in the RSSI value measurement. A first access point with a higher RSSI value than a second access point may actually provide a lower bit rate due to its half-duplex operation.

[0009] Finally, the topology of the BSS network also influences the bit rate that an access point can provide. Thus, when access points are arranged in series or in a daisy chain, the further a given access point is topologically from the gateway GW (i.e., the more intermediate access points there are between the access point in question and the gateway GW), the more significantly the bit rate that this access point can provide drops. However, this effective bit rate is not reflected in the RSSI value. This is especially true when the links established between the various access points are wireless links (e.g., Wi-Fi links).

[0010] To overcome this problem that RSSI does not represent the bit rate actually provided by an access point, the normative documents referencing 802.11v published by the IEEE introduce the principle of "steering," in which one or more access points send requests to stations asking them to switch from a first access point AP1 to a second access point AP2 (this is known as "client steering") or to switch from one frequency band (e.g., in the case of Wi-Fi, the 2.4 GHz band and the 5 GHz band or the 6 GHz band) to another frequency band (this is known as band steering), according to the steering. These roaming requests are sent in BTM (BSS Transition Management) messages defined in the normative documents referencing 802.11v.

[0011] However, a station receiving such a roaming request is free to remain connected to the access point it has chosen. Thus, a station may connect (or remain connected) to a given access point even if doing so degrades the quality of service of the entire network (i.e., of other access points) and of stations already connected. Thus, a station receiving a roaming request from a first access point AP1 to a second access point AP2 may decide to switch to the second access point AP2, to ignore the request and remain connected to the first access point AP1, or to refuse to change access points.

[0012] In addition, even if stations decide to connect to another access point, many stations decide to return to the first access point AP1 to which they were previously connected immediately after switching to this new access point AP2, even though this choice is not optimal from the perspective of service quality. A back-and-forth, or "ping-pong," ensues between requests from the network to switch to access point AP2 and the stations' choice to reconnect to access point AP1. This can adversely affect the user experience depending on the type of service being performed during this back-and-forth, for example, in the case of real-time services such as VoWi-Fi (voice over Wi-Fi) services, video conferencing services, or document sharing services. In addition to this back-and-forth phenomenon between stations, steering (client steering or band steering) does not avoid the possibility of accumulation, where stations all connect to the same access point. Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention aims to remedy some or all of the above mentioned drawbacks. [Means for solving the problem]

[0014] To this end, the present invention provides a method for communication between a station and at least a first access point belonging to a short-range wireless network identified by a network identifier, said network comprising a plurality of access points, the method is implemented by the Bureau; - receiving a message from the first access point, the message including a network identifier, an identifier of at least one second access point from a plurality of access points, and a value of a connectivity parameter of the second access point; - selecting, from a plurality of access points, an access point to connect to in response to the received at least one connectivity parameter value; - establishing a connection with said access point thus selected using the identifier; The present invention proposes a method including:

[0015] Thus, a station can select an access point to connect to using not only information representative of received signal quality, such as RSSI or SNR, but also connectivity parameters representative of the connectivity that a given access point can provide.

[0016] It will be appreciated that in some cases, the first access point and the second access point may refer to the same access point.

[0017] The connectivity of an access point is understood as what this access point is able to provide in terms of quality of service, bit rate, latency, etc. It is therefore understood that the value of a connectivity parameter associated with an access point represents, in a single value, the quality of connectivity that this access point is able to provide.

[0018] As described below, this value of the connectivity parameter can be used in this way to combine, in a single value, various information about the short-range wireless network and its current use, e.g., the number of stations already connected to the access point, the topology of the network (e.g., the number of links between the access point and the gateway), the nature of the links between the access points (Ethernet or Wi-Fi, dual-band or tri-band, number of transmission channels, etc.), etc.

[0019] The overall quality of service of the BSS network received by the stations is thus improved, as stations no longer connect solely according to their proximity to an access point, but rather according to the level of connectivity that the access point can substantially provide.

[0020] Furthermore, this method limits the impact of the back and forth mentioned above, as there is less "collision" between a roaming request to a first access point and an RSSI measurement that indicates that a second access point would be a better choice.

[0021] Finally, a station implementing this method, by having both station-side, i.e., RSSI, and network-side information of potential access points to connect to, can select an access point to connect to because the station has information related to the connectivity of these potential access points.

[0022] According to a particular feature, said message is a beacon message from said first access point.

[0023] Here, the station knows the values ​​of the connectivity parameters of the access points from which it receives beacon messages. This gives the beacon message a dual purpose in selecting an access point to connect to, since the beacon message allows the station not only to measure the RSSI value of the access point, but also to obtain the value of the connectivity parameter of the access point contained in the beacon message. This therefore avoids sending an additional message to provide the connectivity parameters to the station.

[0024] According to a particular feature, the method further comprises a step of sending a probe request to an access point of the network before receiving said message from said access point containing at least one connectivity parameter.

[0025] Thus, a station receives one or more connectivity parameter values ​​in response to a request, which enables the station to select an access point to connect to. For example, a station may send such a request as soon as the quality of service received by the station is no longer satisfactory, or at regular time intervals, typically when the station is moving and degradation of the signal (and therefore RSSI) received from the access point is predictable.

[0026] According to a particular feature, the access point to connect to is further selected depending on the RSSI value measured by said station.

[0027] Therefore, when selecting an access point to connect to, the station also takes into account the RSSI value it measures, and indeed the access point that is selected and to which the station establishes a connection is more relevant both from the point of view of connectivity and from the point of view of received signal quality.

[0028] The present invention also provides a method for transmitting at least one message to at least one station, said message being transmitted by a first access point belonging to a short-range wireless network identified by a network identifier, said network comprising a plurality of access points; the method being performed by a first access point; - obtaining an identifier (ID_APk) of at least one second access point from a plurality of access points and a value of a connectivity parameter of said second access point; - transmitting to a station said message including a network identifier and at least said identifier of said second access point (APk) thus obtained and at least one value of a connectivity parameter of said second access point; The present invention proposes a method including:

[0029] This transmission method, which is very similar to the communication method implemented on the station side, allows the access point to provide information related to its connectivity through the values ​​of the connectivity parameters it transmits.

[0030] It will be appreciated that in some cases, the first access point and the second access point may refer to the same access point.

[0031] This allows an access point with poor connectivity, for example when many stations already have links established with it, or when its link with the gateway has a low bit rate or high latency, to signal this fact to the stations in question, so that the stations can select another access point to connect to.

[0032] Conversely, an access point with good connectivity may signal itself as such, i.e., as having a high connectivity parameter value, in order to encourage stations to connect to it and offload other access points.

[0033] In that case, the network load is better distributed and bottlenecks or back-and-forth phenomena are limited.

[0034] According to a particular feature, said message is a beacon message.

[0035] An access point can communicate its connectivity parameters in this way in a beacon message, which results in a slight increase in the workload of the access point, but still benefits from the advantages described above.

[0036] According to a particular feature, the method further comprises a step of receiving a probe request from a station, The receipt of a probe request triggers the sending of the message in the form of a probe response.

[0037] The present invention also provides a method for determining at least one connectivity parameter of an access point belonging to a short-range wireless network identified by a network identifier, said network comprising a plurality of access points, said method being performed by a controller belonging to said network, - determining, for at least a first access point from a plurality of access points, a value of a connectivity parameter in response to at least one information representative of at least one link established between said first access point and another access point from the plurality of access points; - transmitting the value of the connectivity parameter of the access point thus determined to at least one of the access points of the network; The present invention proposes a method including:

[0038] Therefore, the value of the connectivity parameter of an access point depends on the network layout, in particular the nature of the links between the access points. In other words, this determination method makes it possible to synthesize the quality of connectivity that this access point can provide, taking into account various information about the short-range wireless network, in the value of the connectivity parameter associated with the access point.

[0039] According to a particular feature of this determination method, the information representative of at least one link belongs to a group of information comprising information about the topology of the network, information about the nature of said link, the latency between access points and the effective bit rate that can be provided by said access point of connectivity parameters.

[0040] This connectivity parameter value may therefore depend on the structure of the network itself (e.g., its graph), the nature of the links established between access points, or even metrics related to the effective quality of service that the access points can provide.

[0041] The present invention also provides a station capable of communicating with at least a first access point belonging to a short-range wireless network identified by a network identifier, said network comprising a plurality of access points, The station, - receiving a message from the first access point, the message including a network identifier, an identifier (AP_IDk) of at least one second access point (APk) from a plurality of access points, and a value of a connectivity parameter of the second access point; - selecting, from a plurality of access points, an access point to connect to in response to the received value of at least one connectivity parameter; - using that identifier to establish a connection with said access point thus selected The present invention relates to a station comprising a processor configured to:

[0042] The present invention also provides an access point belonging to a short-range wireless network identified by a network identifier, said network comprising a plurality of access points, each access point being capable of communicating with at least one station, The access point is - obtaining an identifier (ID_APk) of at least one second access point from a plurality of access points and a value of a connectivity parameter of the second access point of the network; - sending to the station a message including a network identifier and at least the identifier of said second access point (APk) thus obtained and at least one value of a connectivity parameter of said second access point; The present invention relates to an access point comprising a processor configured to:

[0043] The present invention further provides a controller belonging to a short-range wireless network identified by a network identifier, said network comprising a plurality of access points; The controller - determining, for at least a first access point from a plurality of access points, a value of a connectivity parameter in response to at least one information representative of at least one link established between the first access point and another access point from the plurality of access points; transmitting the value of the access point connectivity parameter thus determined to at least one of said access points from a plurality of access points. The present invention relates to a controller comprising a processor configured to:

[0044] According to a particular feature, the controller is embedded in said first access point of the network.

[0045] Thus, implementing the determination method within the access point, whose connectivity parameter values ​​are determined, allows access points and controllers to be pooled in the same equipment, which in turn distributes the determination of connectivity parameter values ​​among various access points in a decentralized manner.

[0046] The invention also relates to a computer program product comprising program code instructions for carrying out one of the methods described above when this program is executed by a computer.

[0047] Other characteristics and advantages of the invention will appear more clearly on reading the following description of particular embodiments thereof, given purely as illustrative and non-limiting examples, and the accompanying drawings, in which: [Brief explanation of the drawings]

[0048] [Figure 1] FIG. 1 illustrates an example of a short-range wireless network. [Figure 2] 2 illustrates a first embodiment of a communication method according to the present invention, implemented in the BSS network of FIG. 1; [Figure 3]2 illustrates a second embodiment of a communication method according to the present invention, implemented in the BSS network of FIG. 1; [Figure 4] 2 illustrates an example of a connectivity parameter determination method according to the present invention implemented in the BSS network of FIG. 1; [Figure 5] FIG. 2 illustrates another example of a "star" short-range wireless network. [Figure 6] FIG. 2 shows a simplified structure of a station of the network of FIG. 1. [Figure 7] FIG. 2 shows a simplified structure of an access point of the network of FIG. 1. [Figure 8] FIG. 2 shows a simplified structure of a controller of the network of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0049] 1. BSS Network Please refer to Figure 1, which shows an example of a short-range wireless network, such as a Wi-Fi network, called a BSS network. Such a short-range wireless network, called a BSS ("Basic Service Set"), is shown in Figure 1. This BSS network can be accessed by at least one terminal device, called a station STA. Such a station can be, for example, a personal computer, a tablet, a smartphone, a connected object, a smart sensor, etc.

[0050] Considering the short distance of these waves (a few meters to a few tens of meters), such a BSS network can include multiple access points (APs) APi (where i is an integer (here, four access points AP1, ..., AP4)) to the BSS network to extend its coverage, which are known as repeaters or extenders. These access points APi are connected to each other using links denoted as BHij, where i and j are integers corresponding to the access points constituting the ends of these links; for example, BH12 is the link connecting access point AP1 to access point AP2. All access points APi share the same SSID ("Service Set Identifier") network identifier that identifies the BSS network. Therefore, stations STAs can connect to the BSS network through any one of the access points APi using a short-range radio wave connection. The access points APi are embedded, for example, in home gateways or, more commonly, in public access devices to wireless networks, called "hotspots."

[0051] In the remainder of this application, the letters i, j, k, and m are used as integer indices for the various access points that are connected to each other by links noted BHij, where i and j identify the two access points APi and APj that constitute the ends of said link BHij.

[0052] The BSS network may further comprise a gateway GW that interfaces the BSS network with another network, such as an access network. The gateway GW is connected to one of the access points, here access point AP1. The BSS network is identified by an SSID network identifier that is owned by all access points that belong to the BSS network.

[0053] As an example, the BSS network can be a home local area network (LAN), and the gateway is the equipment that interconnects the BSS network with a telecommunications carrier's access network. This equipment can be either an ADSL router, a cable modem, or an optical network terminal (ONT).

[0054] Further by way of example, the access network may be a wired access network of the xDSL ("Digital Subscriber Line") type, of an optical type such as an xPON (Passive Optical Network), or of a cable type. As a variant, the access network may be a radio access network or RAN conforming to second to sixth generation communication standards.

[0055] The BSS network finally comprises a module called a controller. This controller CTR may be embedded in a gateway GW, in an access point or in a separate device. As a variant, the network may comprise several controllers CTR.

[0056] As an example, the gateway GW may be embedded in a device such as a box, which further embeds a controller CTR and optionally an access point.

[0057] The BSS network can be, for example, a home Wi-Fi network or a public Wi-Fi network.

[0058] A station STA connects to the BSS network via an access point APi of the BSS network using a link denoted FHi (i is the index of the access point to which the station STA connects). Link FHi is, for example, a wireless link such as a Wi-Fi link. In the example shown in FIG. 1, the station STA is thus connected to access point AP1 using link FH1.

[0059] Therefore, when a station STA is located in the coverage area of ​​several access points, the station STA can connect to any of these access points. However, the classic criterion for selecting an access point to establish a link is the highest RSSI value and / or the highest SNR value. This leads to suboptimal selection in terms of connectivity (quality of service, bit rate, latency, etc.) when two access points that the station STA measures have similar RSSI values ​​provide very different connectivity.

[0060] For example, assuming that access point AP1 does not serve any stations, access point AP2 serves approximately 10 stations, and access point AP2 has a larger RSSI value than that of access point AP1, station STA may still connect to access point AP2 even though access point AP1 may be more advantageous in terms of connectivity.

[0061] To overcome this problem, the general principle of the present invention is to communicate to the station STA an indicator representing the connectivity of the access point, hereinafter referred to as a connectivity parameter and denoted as PCi (where i is the index of the access point APi), which the station STA can then use to select an access point to connect to.

[0062] The connectivity of an access point is understood as what this access point is able to offer in terms of quality of service, bit rate, latency etc. as previously mentioned.

[0063] In some cases, the station STA has connectivity parameters of several access points and can select an access point to establish a connection with according to a given criterion, for example, the access point with the highest value of the connectivity parameter. The station STA can also use one or more RSSI values ​​to select an access point to establish a connection with, which is a good compromise between the service quality that the access point can provide, represented by the connectivity parameter, and the quality of the wireless signal that the station STA receives from this access point, represented by the RSSI value or SNR value.

[0064] Therefore, the station STA has connectivity parameters, which are additional information for selecting an access point to connect to.

[0065] Reference is now made to FIG. 2, which illustrates a first embodiment of the present invention.

[0066] In step S0, at least one of the access points APi of the BSS network obtains at least one value of a connectivity parameter PCk of one of the access points APk of the network. The value of the connectivity parameter PCk thus obtained by the access point APi is not necessarily the value of its own connectivity parameter PCi.

[0067] In step S2, an access point APi transmits a message BCNi containing its identifier ID_APi, the value of the connectivity parameter PCk obtained in step S0, and the SSID identifier of the BSS network. If k≠i, the message BCNi further contains the identifier AP_IDk of the access point APk to which the connectivity parameter PCk corresponds. Similarly, another access point APj can transmit a message BCNj containing its access point identifier ID_APj, the SSID identifier of the BSS network, and at least one connectivity parameter PCm. If m≠j, the message BCNj further contains the identifier ID_APm of the access point APm to which the connectivity parameter PCm included in the message BCNj corresponds.

[0068] In step S3, a station STA that has received the message BCNi sent by an access point APi selects an access point APk (k in this example ranging from 1 to 4) to connect to depending on at least one received value of a connectivity parameter PCk. Various examples of criteria for selecting an access point depending on the thus received connectivity parameters are described below.

[0069] In step S4, the station STA then establishes a connection with the thus selected access point APm.

[0070] In the example shown in FIG. 2, the station STA receives identifiers ID_APi, ID_APj and corresponding connectivity parameters PCi, PCj, and selects either the access point APi or the access point APj according to the received connectivity parameters PCi and PCj.

[0071] Thus, the STA has additional information that enables it to select an access point to connect to, not just using a single metric related to the quality of the received signal, such as RSSI or SNR, but also using connectivity parameters that describe the connectivity that a given access point can provide, e.g., quality of service, bit rate, latency.

[0072] When the station STA receives the values ​​of several connectivity parameters PCi, the station STA can select an access point to connect to by comparing the received connectivity parameter values.

[0073] If the station STA receives the value of only one connectivity parameter PCi, the station STA can select an access point to connect to according to one or more RSSI values ​​determined for one or more access points and the received connectivity parameter PCi. The station STA can, for example, prioritize the access point whose connectivity parameter PCi is received when its value exceeds a certain threshold representing a certain provided connectivity and the measured RSSI value for this access point exceeds a certain threshold representing a certain received signal strength; otherwise, prioritize the access point with the best RSSI.

[0074] 2. Beacon Mode In one embodiment, each of the access points APi transmits a beacon message BCNi at regular time intervals. This beacon message includes the SSID identifier of the network as well as the identifier AP_IDi of the access point APi. This identifier AP_IDi of the access point APi can be, for example, a physical address such as a MAC ("medium access control") address. This beacon message BCNi is used by a station STA capturing a radio signal carrying the beacon message BCNi to determine the RSSI value of the access point APi.

[0075] In addition to this information, the beacon message BCNi contains the value of the connectivity parameter PCj.

[0076] In one embodiment, the connectivity parameters whose values ​​are included in the beacon message BCNi are the connectivity parameters PCi of the access point APi. Thus, now, each access point APi periodically transmits a beacon message BCNi containing the value of its connectivity parameter PCi, its identifier AP_IDi and the SSID identifier of the network to which it belongs, so that the station is aware of all the connectivity parameters PCi of the access point APi from which it captures its beacon message BCNi.

[0077] In another embodiment, a beacon message BCNi transmitted by an access point APi contains information relating to n individual access points APi in the form of n pairs (AP_IDi, PCi), each pair containing an identifier AP_IDi of an access point and a corresponding value of its connectivity parameter PCi. A station can thus use a single beacon message to select an access point to connect to. The number n of pairs included in the beacon message may be equal to the number N_AP of access points in the BSS network. As a variant, only a certain number of pairs are included in the beacon message, for example the n pairs with the highest connectivity parameter values.

[0078] As explained above, beacon messages are transmitted at regular time intervals, which may be defined, for example, by a TBTT (Target Beacon Transmission Time) parameter.

[0079] 3. Probe / Response Mode Referring to Figure 3, which illustrates another embodiment of the method described above, steps S3 and S4 of the method of Figure 3 are identical to steps S3 and S4 of the method illustrated by Figure 2.

[0080] In this alternative embodiment, which is consistent with the first embodiment, one or more connectivity parameters are obtained via a probe request / probe response exchange between the station STA and the access point.

[0081] Here, in step S1, the station STA sends a probe request PReq, which means that the station STA wants to obtain information about the connectivity of access points before selecting an access point to connect to. The probe request can be sent to a specific access point, for example, an access point from which the station receives beacon messages, or it can be broadcast to all access points located near the station STA and likely to receive the probe request PReq.

[0082] In step S2', the station STA receives a probe response PRepi from at least one access point APi, the probe response PRepi including at least one value of a connectivity parameter PCi, an SSID identifier of the BSS network, and an access point identifier AP_IDk.

[0083] More specifically, the probe response PRepi sent by the access point APi contains the identifier AP_IDi of this access point, the value of the connectivity parameter PCi of this access point and the SSID identifier of the BSS network.

[0084] Here, an access point that receives a probe request can send back its own identifier and connectivity parameters, which reduces the amount of data exchanged, as each access point only needs to send information related to its own connectivity to the station.

[0085] The probe response here may not be sent automatically in response to receiving a probe request and may be at the discretion of the access point. The access point may choose not to return the connectivity parameter, for example, if it considers its load to be too high, i.e., if too many stations have already established links with it or if stations are already consuming too much bandwidth, resulting in, for example, a low connectivity parameter PCi value.

[0086] According to another example, a probe response PRepi includes n pairs (AP_IDi, PCi) for n distinct access points APi, each pair including an identifier AP_IDi of the access point and a corresponding value of its connectivity parameter PCi. For the reasons explained above, the number of pairs n can be less than or equal to the number of access points. This allows all or part of the connectivity parameters to be fed back in a single probe response PRepi.

[0087] 4. Determine connectivity parameters The exchanges between a station STA and one or more access points have been described above, which enable the station STA to obtain one or more values ​​of connectivity parameters relating to one or more access points. Reference is now made to Figure 4, which shows a method for determining the value of the connectivity parameter PCi of an access point. This method is implemented by a controller CTR. As a variant, the BSS network may comprise several controllers, as described above.

[0088] The method comprises a step S10 of determining a value of a connectivity parameter PCi of a first access point APi, and a step S12 of transmitting this value thus determined to another access point APj, which may be the first access point APi or a different access point.

[0089] The value of a connectivity parameter PCi is determined in response to at least one piece of information representative of at least one link BHij established between the first access point APi and at least one second access point APj of a BSS network.

[0090] The arrangement of network access points, or the topology of a BSS network, defines a graph of the BSS network, where the nodes of the graph are access points and the edges of the graph are links connecting two access points together. In the example shown in Figure 1, the access points are connected in series, i.e., a given access point is connected to at most two other access points.

[0091] Alternatively, the access points may be arranged in a star shape around a central access point, in which case the graph is known as a "star" graph, or may be arranged in a mesh, as with the network shown in Figure 5. Of course, the network graph can be a combination of these various BSS network topologies, the only constraint on this graph being that it must be connected (i.e., unitary).

[0092] The inventors have found that the topology of the BSS network is a relevant factor for determining the connectivity parameter PCi. In the following, the BSS network graph is considered to be acyclic, or in other words, a tree whose root is the access point AP1 closest to the gateway GW. Since access points are nodes in the BSS network tree and parent access points are closer to the root than child nodes, the terms parent access point and child access point in the graph-theoretic sense will be used below, and the terms BSS network tree and BSS network graph will be used interchangeably below.

[0093] Thus, in the first embodiment, the connectivity parameter PCi is a function of the distance of the access point APi from the gateway GW: the further away the access point APi is, i.e. the more intermediate access points APi there are between the access point in question and the gateway GW, the lower the value of the connectivity parameter PCi.

[0094] For example, the value of the connectivity parameter PCi may be calculated using the formula PCi=100 / (1+N_BH), where N_BH represents the number of links between the access point APi and the gateway GW. In the example shown in Figure 1, the connectivity parameters PCi are 100 for the access point AP1 (N_BH=0), 50 for the access point AP2 (N_BH=1), 33.3 for the access point AP3 (N_BH=2), and 25 for the access point AP4 (N_BH=3), respectively.

[0095] This option for counting the number of links between access points is particularly relevant when access points communicate with each other using wireless links in "half-duplex" mode. In fact, in this case, the further an access point is from the gateway GW, the more its connectivity depends on how the bandwidth is used by intermediate access points located between the access point and the gateway. Similarly, the wireless nature of the link affects its connectivity. In fact, wireless links are inherently more sensitive to electromagnetic interference, and data transmitted using these links is more prone to loss.

[0096] This formula PCi=100 / (1+N_BH) can be generalized as PCi=f(N_BH), where f is a decreasing function. Thus, the determination of the connectivity parameter PCi value takes into account the network topology, for example the number of links between the gateway GW and the access point APi whose connectivity parameter PCi value the controller is trying to determine.

[0097] In the case of a non-serial network topology, the above function f may take into account other topology parameters related to branches of the BSS network tree to which the access point APi does not belong, for example, so that the value of the obtained connectivity parameter PCi of the access point APi reflects the influence of other access points that share the same parent access point as the access point APi on the connectivity of the access point APi in question. In the case of a mesh (or cyclic graph), the function f is quite different.

[0098] In a second embodiment, the connectivity parameter PCi takes into account not only the number of links existing between the access point APi and the gateway, but also their nature. In practice, Ethernet links, and more generally wired links, are more reliable than Wi-Fi links in terms of packet loss, susceptibility to electromagnetic waves, etc. In addition, when an access point is connected to its neighboring access points using wired links, the access point retains all the radio resources available to it for communicating with the stations to which it is connected.

[0099] Therefore, each link BHij is assigned here a weight bh_type, for example ranging from 0 to 1, that represents the nature of this link, e.g., bh_type=1 for an Ethernet type link BHij, bh_type=0.9 for a tri-band Wi-Fi type link, bh_type=0.3 for dual-band Wi-Fi, etc. These weights are given here for illustrative purposes, and the underlying idea is that the closer these weights are to 1, the more likely the corresponding link is to transmit data without degrading the connectivity of the access points.

[0100] In this case, the value of the connectivity parameter PCi of the access point APi may be defined according to the formula PCi=PCj*bh_type_ij, where PCj is the connectivity parameter of the parent access point APj of the access point APi (in the sense of the tree forming the BSS network graph).

[0101] Thus, an access point connected to its parent access point by an Ethernet link has the same connectivity as its parent access point. On the contrary, an access point connected to its parent access point via a dual-band Wi-Fi link not only has a lower connectivity parameter value than its parent access point, but this also affects the connectivity of its child access points.

[0102] The type of link connecting the two access points together can be Ethernet, dual-band Wi-Fi, tri-band Wi-Fi, PLC (Power Line Communication), Home PNA ("Home Phone Line Networking Alliance"), coaxial link (MOCA, short for "Multimedia Over Coax Alliance"), plastic optical fiber (POF), optical fiber, etc.

[0103] In a third embodiment, the calculation of the connectivity parameter PCi of an access point APi also takes into account the number of transmission channels or "spatial streams" of the access point when the access point is equipped with multiple transmit antennas.

[0104] Here, the value of the connectivity parameter PCi is given by the following equation: PCi=PCj*bh_type_ij*(1-1 / min(NSS_APi_BHij, NSS_APi_BHik)) j is the index of the parent access point of APi, k is the index of the child access point APk of APi, and NSS_APi is the number of spatial streams NSS of the access point APi.

[0105] In this embodiment, a parameter NSS_APi_BHij is further specified that describes the nature of the link BHij, its type as well as its capabilities, both for communicating with other access points and for communicating with the stations to which it is connected. The number of spatial streams NSS provides an approximation of the available bandwidth for the link BHij.

[0106] In another embodiment, the determination of the connectivity parameter PCi is - information representative of the effective bit rate that can be provided by an access point APi or between said access point APi and a gateway GW or between a root access point AP1 of a BSS network and said access point APi, - information representing the latency measured between the access point APi and the gateway GW or between the root access point AP1 of the BSS network and the access point APi; can be considered.

[0107] The method for determining the connectivity parameters has been described as being implemented by the controller CTR. However, it is conceivable to decentralize the determination of the connectivity parameter PCi values, with each access point APi receiving, for example, the value of the parameter PCj of its parent access point APj and, knowing the nature of its links, being able to deduce the value of its own connectivity parameter PCi.

[0108] Therefore, the connectivity parameters of the access points are determined within the short-range wireless network. This allows stations wishing to connect to the network to be provided with only one piece of connectivity information, rather than multiple pieces of information about the entire short-range wireless network. The exchange between the stations and the access points is lighter. In addition, this allows the short-range wireless network (particularly the controller) to control its policy for distributing station connections to the access points of the short-range wireless network by controlling the connectivity parameter values ​​that are transmitted.

[0109] Optionally, a single connectivity parameter value is determined for each access point.

[0110] 5. Selection Criteria In step S3, the station STA selects an access point to connect to based on the one or more received connectivity parameters PCi.

[0111] The selection is made based on a selection criterion, which may be one of the following criteria: - selecting the access point whose connectivity parameter PCi has the highest value among the received connectivity parameter PCi values ​​(the criterion for the highest connectivity parameter value); - selecting the access point with the highest RSSI value among the access points whose connectivity parameter value exceeds a given threshold (the measure of the highest RSSI among access points with at least a certain connectivity); - selecting the access point whose connectivity parameter value is the highest among the access points whose RSSI value measured by the station exceeds a given threshold (a criterion for best connectivity among access points having at least a certain RSSI value); - randomly selecting an access point among the access points whose connectivity parameter value exceeds a first threshold and whose RSSI value exceeds a second threshold (criterion for random selection among access points having at least a certain connectivity and at least a certain RSSI value); - Selecting an access point according to the criterion of the highest RSSI value when the value of the received connectivity parameter does not exceed a certain threshold (criterion of the best signal quality if the access point does not exceed a certain quality of service).

[0112] These examples are proposed here for illustrative and non-limiting purposes, and it is of course possible to combine criteria relating to connectivity parameters with criteria relating to other indicators (RSSI, SNR or other criteria).

[0113] The connectivity parameters may be determined at regular intervals. For example, the controller may determine these connectivity parameters every minute, every second, or every n milliseconds.

[0114] Connectivity parameters may also be determined when certain events occur, such as the failure of an access point or the addition / removal of an access point to / from the network.

[0115] Connectivity parameters have been described whose all higher values ​​result in an access point with higher connectivity. As a variant, it is possible to define connectivity parameters whose all lower values ​​result in an access point with higher connectivity. In this case, a station selects an access point by preferring low connectivity parameter values.

[0116] The determined connectivity parameters can be sent to all access points (thus having a connectivity "map" of all access points of the network), or only to the access point to which it corresponds if that access point has not yet performed its own connectivity parameter determination. The connectivity parameters can also be sent to another access point in response to a request from that access point.

[0117] device As shown in FIG. 6, a station STA according to an embodiment of the present invention comprises a memory M and a processing unit, for example a programmable or dedicated computing machine, for example a processor P, for executing a computer program Pg implementing the steps of a communication method according to at least one embodiment of the present invention.

[0118] At initialization, the code instructions of the computer program Pg are loaded into a RAM memory before being executed by the processor of the processing unit P, for example.

[0119] The processor of the processing unit P performs the steps of the communication method previously described according to the instructions of the computer program Pg.

[0120] As shown in Figure 7, an access point AP according to an embodiment of the present invention comprises a memory M and a processing unit, for example a programmable or dedicated computing machine, for example a processor P, for executing a computer program Pg implementing the steps of a communication method according to at least one embodiment of the present invention.

[0121] At initialization, the code instructions of the computer program Pg are loaded into a RAM memory before being executed by the processor of the processing unit P, for example.

[0122] The processor of the processing unit P performs the steps of the communication method previously described according to the instructions of the computer program Pg.

[0123] As shown in FIG. 8, a controller CTR according to an embodiment of the present invention comprises a memory M and a processing unit, for example a programmable or dedicated computing machine, for example a processor P, for executing a computer program Pg implementing the steps of the communication method according to at least one embodiment of the present invention.

[0124] At initialization, the code instructions of the computer program Pg are loaded into a RAM memory before being executed by the processor of the processing unit P, for example.

[0125] The processor of the processing unit P performs the steps of the communication method previously described according to the instructions of the computer program Pg.

[0126] A separate controller CTR and access points AP have been described. In one embodiment of the present invention, these two players of the BSS network are implemented in the same device, for example a "box" device that embeds the gateway GW, the controller CTR and one of the access points. [Explanation of symbols]

[0127] AP Access point AP1 Access Point, first access point AP2 Access Point, Second Access Point AP3 Access Point AP4 Access Point APi Access Point, first access point APj Access point, second access point, another access point, parent access point BCNi Message BCNj Messages BH12 Link CTR Controller FH1 Link GW Gateway M Memory P processor Pg Computer Program PReq probe request PRepi probe response STA station

Claims

1. 1. A communication method for communication between a station (STA) and at least a first access point (APi) belonging to a short-range wireless network (BSS) identified by a network identifier (SSID), said network comprising a plurality of access points, the method being performed by the station; - receiving (S2, S2') from said first access point (APi) a message (BCNi, PRepi) comprising said network identifier (SSID) and at least one value of a connectivity parameter (PCk) of a second access point (APk) from said plurality of access points; - selecting (S3) from said plurality of access points an access point (APm) to connect to depending on said at least one received value of a connectivity parameter (PCk); - establishing (S4) a connection with the access point (APm) thus selected; A communication method, including:

2. The communication method of claim 1 , wherein the message further includes an identifier (AP_IDk) of a second access point (APk) from the plurality of access points.

3. The communication method according to claim 1, wherein the message is a beacon message (BCNi) from the first access point (APi).

4. before receiving (S2) said message (PRepi) from said access point (APi) containing said at least one connectivity parameter (PCk), 2. The communication method of claim 1, further comprising the step of sending (S1) a probe request (PReq) to the access point of the network.

5. 2. The communication method according to claim 1, wherein the access point to connect to is further selected (S3) depending on an RSSI value measured by the station.

6. 1. A method for transmitting at least one message (BCNi, PRepi) to at least one station (STA), said message being transmitted by a first access point (APi) from a plurality of access points belonging to a short-range wireless network (BSS) identified by a network identifier (SSID), the method is performed by the first access point (APi), - obtaining (S0) at least one value of a connectivity parameter (PCk) of a second access point (APk) from said plurality of access points; - transmitting (S2, S2') to the station (STA) the message (BCNi, PRepi) containing the network identifier (SSID) and the at least one value of the connectivity parameter (PCk) of the second access point (APk) thus obtained; A method comprising:

7. The method of claim 5, wherein the message (BCNi, PRepi) further includes an identifier (AP_IDk) of a second access point (APk) from the plurality of access points.

8. The method of claim 6, wherein the message is a beacon message (BCNi).

9. The method further includes receiving (S1) a probe request (PReq) from the station (STA); said reception (S1) of said probe request triggers said sending (S2') of said message in the form of a probe response (PRepi); The method of claim 6.

10. 1. A method for determining at least one connectivity parameter (PCi) of an access point (APi) from a plurality of access points belonging to a short-range wireless network (BSS) identified by a network identifier (SSID), the method being performed by a controller (CTR) belonging to said network, - determining (S10), for at least said access point (APi), a value of a connectivity parameter (PCi) depending on at least one piece of information representative of at least one link (BHij) established between said access point (APi) and a second access point (APj) from said plurality of access points; - transmitting (S12) to at least one of the access points (APk) of the plurality of access points of the network the value of the connectivity parameter (PCi) of the access point (APi) thus determined; A method of determining

11. 11. The method of claim 10, wherein the information representing at least one link (BHij) belongs to a group of information including information about the topology of the network, information about the nature of the link (BHij), latency between access points (APi, APj), and effective bit rates that can be provided by the access points (APi, APj) of the connectivity parameters (PCi, PCj).

12. A station (STA) capable of communicating with at least a first access point (APi) from a plurality of access points belonging to a short-range wireless network (BSS) identified by a network identifier (SSID), The station (STA) - receiving (S2, S2') from said first access point (APi) a message (BCNi, PRepi) including said network identifier (SSID) and at least one value of a connectivity parameter (PCk) of a second access point (APk) from said plurality of access points; - selecting (S3) from said plurality of access points an access point (APm) to connect to depending on said at least one received value of said connectivity parameter (PCk); - establishing (S4) a connection with the access point (APm) thus selected; A station (STA) comprising a processor configured to:

13. an access point belonging to a short-range wireless network (BSS) identified by a network identifier (SSID), the network comprising a plurality of access points, the access point being capable of communicating with at least one station (STA); The access point (APi) - obtaining (S0) at least one value of a connectivity parameter (PCk) of a second access point (APk) from the plurality of access points; - sending (S2, S2') to said station (STA) a message (BCNi, PRepi) containing said network identifier (SSID) and said at least one value of said connectivity parameter (PCk) of said second access point (APk) thus obtained; 1. An access point comprising: a processor configured to:

14. a controller belonging to a short-range wireless network (BSS) identified by a network identifier (SSID), the network comprising a plurality of access points; The controller (CTR) - determining (S10) for at least a first access point (APi) from said plurality of access points a value of a connectivity parameter (PCi) in response to at least one piece of information representative of at least one link (BHij) established between said first access point (APi) and a second access point (APj) from said plurality of access points; - transmitting (S12) to at least one of the access points (APk) from the plurality of access points the value of the connectivity parameter (PCi) of the first access point (APi) thus determined; a controller comprising a processor configured to:

15. The controller of claim 14 embedded in the first access point of the network.

16. A computer program product comprising program code instructions, which when executed by a station or an access point, respectively, performs the method of any one of claims 1 to 5 and 6 to 9.

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