Patent Description:
The invention finds application in particular in <NUM>. 11ba networks.

In recent years, the number of battery-powered devices has increased strongly with cellular telephones, tablets, laptop computers, wearable devices, Internet of Things (IoT) devices and so on. Consequently, nowadays, a key consideration in wireless system design is the optimal use of the power consumption.

For example, <CIT> discloses a method of receiving, by a low power radio of a station, a wake up signal from an access point of a network the station is connected to, the wake up signal being configured to fully wake a wireless local area network radio of the station and receiving, by the WLAN radio of the station, a beacon indicating a data transmission is pending for the station.

In such a context, the IEEE <NUM> standard organization has launched a new task group, IEEE <NUM>. 11ba, in which the definition of an ultra-low power consumption Wake-Up Radio (WUR) module is studied.

A wireless device comprising a radio module compliant with the IEEE <NUM>. 11a/b/n/ac/ax standards, referred to as a PCR and coupled with a WUR module is considered. The objective of the WUR module is to wake up the PCR on-demand, only when it is necessary (e.g., only when there are data to transmit). In this way, the PCR can enter more frequently in doze mode; hence, the power consumption is reduced. The power consumption requirements related to WUR module are very strong with an objective of drawing less than <NUM> microwatts when it is awake. Depending on the implementation, the WUR module may be always awake or awake only when PCR is in doze mode.

During the system operation, the AP may need to send update information to its associated non-AP stations. In a first case (referred to as broadcast case), the update information may concern all its associated non-AP stations or a group of its associated non-AP stations. In a second case (referred to as unicast case), the update information may concern only one station. Moreover, the update information may either be used to update value(s) relative to WUR parameter(s) and/or relative to PCR parameter(s).

In the broadcast case, a problem is that some non-AP stations may have their PCR module awake, while others may have their PCR module in doze mode. However, the update information is sent to all non-AP stations (or all non-AP stations of the group). Hence, it is restrictive, in terms of latency, to wait for the Wake-Up (for an update information directed to the PCR module) or the sleeping (for an update information directed to the WUR module) of all non-AP stations to apply the update information.

Similarly, in the unicast case, the targeted non-AP station may have a PCR module either awake or in doze mode, and the update information may concern either the PCR module or the WUR module. Hence, it is also restrictive, in terms of latency, to wait for the Wake-Up (i.e. for an update information directed to the PCR module) or the sleeping (for an update information directed to the WUR module) of the targeted non-AP station to apply the update information.

There is thus a need to improve existing communication methods between an AP and non-AP stations comprising a PCR module and WUR module.

The present invention has been devised to address one or more of the foregoing concerns.

In this context, according to a first aspect of the invention, there is provided a communication method in a wireless communication network comprising at least one network cell (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the method comprising the steps of claim <NUM>.

Therefore, the update information may be applied to all the station with no latency, no matter their PCR module / WUR module are awake or in doze mode.

Correspondingly, there is provided an access point in a wireless communication network as disclosed in claim <NUM>.

The access point has the same advantages as the method according to the first aspect defined above.

Optional features of the invention are further defined in the dependent appended claims.

According to a second aspect of the invention, there is provided a communication method in a wireless communication network at least one network cell (BSS), each cell comprising at least one station (non-AP) managed by an access point (AP), the method comprising the steps of claim <NUM>.

Therefore, the update information may be applied to the targeted station with no latency, no matter if its PCR module / WUR module is awake or in doze mode.

Correspondingly, there is provided an access point (AP) in a wireless communication network as disclosed in claim <NUM>.

Further advantages of the present invention will become apparent to those skilled in the art upon examination of the drawings and detailed description. Embodiments of the invention will now be described, by way of example only, and with reference to the following drawings.

In the following description, all the items referred to by the same numeral reference are identical.

<FIG> illustrates a wireless communication system in which embodiments of the invention may be implemented.

Wireless communication system <NUM> includes three wireless devices, an Access Point (AP) <NUM> and two non-AP stations <NUM> and <NUM>. Each device comprises two wireless communication modules. A first one, referred to as the primary connectivity radio (PCR), corresponds to the main radio thought which wireless data are exchanged. It may be compliant with IEEE <NUM> standard technology, for instance as defined in <NUM>. 11a/b/n/ac/ax standards. A second one, referred to as Wake-Up Radio (WUR) or WUR module or Wake-Up receiver, corresponds to the companion radio of PCR. It is a low-power-consumption radio one objective of which is to wake up the PCR of a non-AP station only when the PCR has data to send or receive from another radio.

Correspondingly, the AP <NUM> includes a PCR <NUM> and a WUR <NUM>, the non-AP station <NUM> includes a PCR <NUM> and a WUR <NUM> and the non-AP station <NUM> includes a PCR <NUM> and a WUR <NUM>.

A wireless communication module is considered OFF or in doze mode when it is not able to receive and transmit data. Inversely, a wireless communication is considered ON (i.e. set to ON) or awake when it is able to receive and transmit data. Basically, in a non-AP station, when the PCR is OFF, the WUR is ON and inversely when the PCR is ON, the WUR is OFF. In an alternative embodiment, the WUR may be always ON.

A shown in <FIG>, the non-AP station <NUM> has a PCR <NUM> OFF and a WUR <NUM> ON and the non-AP station <NUM> has a PCR <NUM> ON and a WUR <NUM> OFF. Consequently, the use of the WUR radio allows the power consumption of the non-AP station <NUM> to be reduced because its PCR is OFF.

As the PCR <NUM> is ON, the frames <NUM>, referred to as PCR frames, may be exchanged between the PCR <NUM> of the AP <NUM> and the PCR <NUM> of the non-AP station <NUM> as during a typical wireless IEE <NUM> transmission session. Such PCR frames <NUM> are not received by the PCR <NUM> of the non-AP station <NUM> because this one is OFF.

When the AP <NUM> has PCR data to send to the non-AP station <NUM>, it needs to wake up the PCR <NUM>. To do so, it uses its WUR <NUM> to transmit a frame <NUM>, referred to as a WUR frame. A WUR frame consists of a legacy IEEE <NUM> preamble and a payload modulated by a so-called ON-OFF key (OOK) scheme. As described further hereafter with reference to <FIG>, the WUR frame comprises synchronization information, a receiver's address and other transmission information. A WUR Wake-Up frame is a particular type of WUR frame which is used to wake up the PCR module of the non-AP station. Such a WUR Wake-Up frame <NUM> is received by the WUR <NUM> of the non-AP station <NUM>. This latter, after checking that the WUR Wake-Up frame <NUM> is for its attention, generates a Wake-Up signal <NUM> for the attention of the PCR <NUM> to wake up it. At this instant, the PCR <NUM> becomes ON, the WUR <NUM> may become OFF and a PCR transmission may be initiated between the PCR <NUM> of the AP <NUM> and the PCR <NUM> of the non-AP station <NUM>.

In the following description, as the PCR is the main communication module, a non-AP station is said in doze mode when its PCR is OFF and awake when its PCR is ON.

Moreover, when the power management is activated between an AP and a non-AP station, a non-AP station is either in active mode or in Power Saving (PS) mode. In active mode, the non-AP station may receive and transmit frames at any time. In other words, the non-AP station is always awake. In PS mode, the non-AP station is awake only when frames have to be received or transmitted. The non-AP station is thus in doze mode otherwise. Nevertheless, in doze mode, a non-AP station may wake up periodically to listen to beacon frames (sent by the AP) which may comprise a Traffic indication map (TIM) indicating that it is necessary for the station to enter in an awake state. Moreover, in doze mode, a non-AP station is able to send dedicated frames (PS-Poll) to the AP in order to enter latter in an awake state (to transmit data). Consequently, at any time, an AP may know the state of a non-AP station (i.e. whether a non-AP station is in doze mode or awake).

<FIG> is a block diagram showing an exemplary architecture of a communication device <NUM> according to embodiments of the present invention. For instance, the communication devices <NUM> may correspond to the Access Point <NUM> or to the non-AP station <NUM>/<NUM> of the communication system <NUM> shown in <FIG>.

For illustration purposes only, the communication device <NUM> may be a vehicle, a home appliance or another embedded item with electronics, software, sensors and connectivity enabling objects to connect and exchange data. More specifically, it is well adapted for device referred to as Internet of Things (IoT) devices that are battery powered and require low-power operation and communication.

In this example, the communication device <NUM> comprises a communication bus <NUM> to which there are preferably connected:.

Optionally, the communication device <NUM> may also include the following components:.

The communication device <NUM> may be optionally connected to various peripherals, such as for example a digital camera <NUM>, each being connected to an input/output card (not shown) so as to supply data to the communication device <NUM>.

Preferably the communication bus provides communication and interoperability between the various elements included in the communication device <NUM> or connected to it. The representation of the bus is not limiting and in particular the central processing unit is operable to communicate instructions to any element of the communication device <NUM> directly or by means of another element of the communication device <NUM>.

The disk <NUM> may optionally be replaced by any information medium such as for example a compact disk (CD-ROM), rewritable or not, a ZIP disk, a USB key or a memory card and, in general terms, by an information storage means that can be read by a microcomputer or by a microprocessor, integrated or not into the apparatus, possibly removable and adapted to store one or more programs whose execution enables a method according to the invention to be implemented.

The executable code may optionally be stored either in the read only memory <NUM>, on the hard disk <NUM> or on a removable digital medium such as for example the disk <NUM> described previously. According to an optional variant, the executable code of the programs can be received by means of the communication network <NUM>, via the interface <NUM>, in order to be stored in one of the storage means of the communication device <NUM>, such as the hard disk <NUM>, before being executed.

The central processing unit <NUM> is preferably adapted to control and direct the execution of the instructions or portions of software code of the program or programs according to the invention, which instructions are stored in one of the aforementioned storage means. On powering up, the program or programs that are stored in a non-volatile memory, for example on the hard disk <NUM> or in the read only memory <NUM>, are transferred into the random access memory <NUM>, which then comprises the executable code of the program or programs, as well as registers for storing the variables and parameters necessary for implementing the invention.

In a preferred embodiment, the apparatus is a programmable apparatus which uses software to implement the invention. However, alternatively, the present invention may be implemented in hardware (for example, in the form of an Application Specific Integrated Circuit or ASIC).

<FIG> shows the format of a Wake-Up Radio (WUR) frame <NUM> as defined in the IEEE <NUM>. 11ba standard.

The WUR frame <NUM> comprises a "Frame Control" field <NUM>, an "Address" field <NUM>, a "TD Control" field <NUM>, a "Frame Body" field <NUM> and a "FCS" field <NUM>. "FCS" is for Frame Check Sequence. It is for instance a so-called CRC.

The fields <NUM>, <NUM> and <NUM> form the MAC header of the WUR frame. The MAC header and "FCS" field <NUM> form the minimal WUR frame format and are present in all WUR frames.

The "Frame Control" field <NUM> comprises a "Type" subfield <NUM> and a "Reserved" subfield <NUM>. The "Type" subfield <NUM> indicates the type of the WUR frame, referred to as WUR frame type. It is coded on <NUM> or <NUM> bits. Four WUR frame types are defined and listed in the table <NUM>: "WUR Beacon" coded by value <NUM>, "WUR Wake-Up" coded by value <NUM>, "WUR Vendor Specific" coded by value <NUM> and "WUR Discovery" coded by value <NUM>.

The "Address" field <NUM> comprises an identifier for the WUR frame, referred to as a WUR identifier. It is coded on <NUM> bits. Three WUR identifiers are defined and listed in the table <NUM>: "Transmit ID", "Group ID", and "Wake-Up ID". "Transmit ID" corresponds to an identifier of the transmitting AP so that a frame including such a Transmit ID is for the attention of all the stations controlled by the identified AP. "Group ID" corresponds to an identifier of a group of non-AP stations. "Wake-Up ID" corresponds to an Identifier of a given (targeted) non-AP station.

The "Frame Body" field <NUM> is a variable-length field that comprises information specific to specific individual WUR frame types.

The "FCS" field <NUM> may comprise a Cyclic Redundancy Check (CRC). The size of CRC may be CRC-<NUM>, CRC-<NUM> or CRC-<NUM>. The FCS is calculated over at least some or all the fields of the WUR frame, e.g., the "Frame Control" field <NUM>, the "Address" field <NUM>, the "TD Control" field <NUM>, the "Frame Body" field (if present) <NUM>, and also a BSSID value. These fields are referred to as the calculation fields. The BSSID value is part of the calculation but it is not included in the WUR frame transmitted over the wireless medium.

The format of each WUR frame inherits from its general WUR frame format and according to its WUR frame type, some fields are present or not.

Hence, the frame format of a WUR Beacon frame may comprise all fields but the "Frame Body" field <NUM>. For this frame, the "Type" subfield <NUM> of the "Frame Control" field <NUM> is set to <NUM>, and the "Address" field <NUM> may comprise the "Transmit ID".

As another example, the frame format of the WUR Wake-Up frame may comprise all fields. For such a frame, the "Type" subfield <NUM> of the "Frame Control" field <NUM> is set to <NUM>, the "Address" field <NUM> comprises the "Wake-Up ID" of the targeted non-AP station when the WUR frame is individually addressed, the "Group ID" when the WUR frame is addressed to a group of stations, the "Transmit ID" when the WUR frame is broadcast and <NUM> when multiple "Wake-Up ID" are included in the frame body of the WUR frame <NUM>.

<FIG> shows the format of an <NUM> MAC Action frame including a WUR Action field as defined in the IEEE <NUM>. 11ba standard. In such a case, the frame is referred to as WUR Action frame. It is recalled that an <NUM> MAC Action frame is a management frame used to trigger an action. A WUR Action frame is used to negotiate the parameters related to WUR operations in the primary connectivity radio.

The WUR Action frame <NUM> comprises an "Action" field <NUM> (referred to as WUR Action field) in its "Frame Body" field <NUM>.

The "Action" field <NUM> comprises a "WUR Mode Element" field <NUM> that is used to negotiate the parameters related to WUR operations. It comprises an "Action Type" field <NUM>, a "WUR Mode Response Status" field <NUM> and a "WUR Parameters" field <NUM>.

The "Action Type" field <NUM> comprises a number that identifies the type of WUR mode operation. It may be coded on <NUM> bits. Six types of WUR mode operations are defined and listed in table <NUM>: "Enter WUR Mode Request" coded by value <NUM>, "Enter WUR Mode Response" coded by value <NUM>, "Enter WUR Mode Suspend Request" coded by value <NUM>, "Enter WUR Mode Suspend Response" coded by value <NUM>, "Enter WUR Mode Suspend" coded by value <NUM> and "Enter WUR Mode" coded by value <NUM>. The values between <NUM> and <NUM> are reserved.

The "WUR Mode Response Status" field <NUM> indicates the status returned by the AP responding to the non-AP STA's WUR Mode request operation. This field is valid only when the "Action Type" field <NUM> is set to "Enter WUR Mode Response" or "Enter WUR Mode Suspend Response" and is reserved otherwise. Two status are defined: "Accept" coded by value <NUM> and "Denied" coded by value <NUM>.

The "WUR Parameters" field <NUM> comprises several subfields. If the WUR Action frame <NUM> is sent from the WUR module of the AP, it comprises a list of subfields <NUM> including a "WUR ID" subfield <NUM> and a "Duty Cycle Information" subfield <NUM>. The "WUR ID" subfield <NUM> corresponds to the WUR identifier that uniquely identifies a station within the BSS managed by the AP, referred to as Wake-Up ID. If the WUR Action frame is sent from the WUR module of a non-AP station, it comprises a list of subfields <NUM> including an "ON Duration" subfield <NUM> and a "Duty Cycle Period" subfield <NUM>. The duty cycle corresponds to the period for which the WUR of a non-AP station is able to receive WUR frames when it is ON.

<FIG> including <FIG>, shows fields/subfields/values added to the WUR frame and <NUM> MAC Action frame (including a WUR Action field) formats shown in <FIG> and <FIG>, according to embodiments of the invention.

<FIG> represents a table <NUM> listing the WUR frame types according to embodiments of the invention. In addition to the current version of IEEE <NUM>. 11ba (illustrated by the table <NUM>), a first new WUR frame type referred to as "WUR Broadcast Identifiers modification" is defined and coded by value <NUM> and a second new WUR frame type referred to as "WUR Unicast Identifiers modification" is defined and coded by value <NUM>. Obviously, other code values can be used.

<FIG> represents a table <NUM> listing the types of WUR mode operation according to embodiments of the invention. In addition to the current version of the IEEE <NUM>. 11ba (illustrated by the table <NUM>), five new types of WUR mode operation are defined: "WUR identifiers collision identification" coded by value <NUM>, "Wake Up ID collision identification" coded by value <NUM>, "Transmit ID collision identification" coded by value <NUM>, "Group ID collision identification" coded by value <NUM>, and "WUR identifiers collision identification response" coded by value <NUM>. Obviously, only certain of these values could be used and other values can be used.

<FIG> represents a list of subfields <NUM> included in a "WUR Parameters" field <NUM> of a "WUR Mode Element" of a WUR action frame <NUM>. In addition to the current version of the IEEE <NUM>. 11ba, a first new subfield "Transmit ID" <NUM> is defined corresponding to a new Transmit ID to be applied (by the non-AP stations), a second new subfield "Hash Identifier" <NUM> is defined corresponding to a new identifier of a predetermined WUR identifiers hash function to be applied (by the non-AP stations),a third new subfield "Wake-Up ID" <NUM> is defined corresponding to a new Wake-up ID to be applied (by the intended non-AP station), and a fourth new subfield "Group ID" <NUM> is defined corresponding to a new Group ID to be applied (by the targeted non-AP stations).

<FIG> including <FIG>, illustrates, using flowcharts, steps of communication methods during which broadcast update information is signaled by an AP to the non-AP stations of its network cell according to embodiments of the invention.

A key advantage of these embodiments is that the broadcast update information is received by all non-AP station regardless of they are in doze mode or awake. In particular, when the update information concerns the PCR module, it is not necessary to wait for the Wake-Up of all non-AP stations to take the updated information into account. Similarly, when the update information concerns the WUR module, it is not necessary to wait for the sleeping of all non-AP stations to take the updated information into account.

Within the wireless communication system <NUM>, some non-AP stations are awake and others are in doze mode. When a non-AP station is in doze mode, it is not able to receive PCR frames but it is able to receive WUR frames from the AP. When a non-AP station is not in doze mode, i.e. it is awake, it is able to receive PCR frames and in some cases, it may be able to receive WUR frames.

According to a first embodiment shown in <FIG>, the AP wakes up all non-AP stations in doze mode using its WUR module and sends a broadcast update information through its PCR module (inside a PCR frame).

At step <NUM>, the AP detects an event indicating that an update information needs to be sent to non-AP stations of its network cell.

Such an event may be triggered by a modification of the network conditions, e.g., a degradation of the QoS, which may depend on environmental factors (e.g., weather conditions), the presence of physical objects, electrical and/or radio frequency interferences, or the arrival/exit of a non-AP station in the network cell.

Such an event may also be triggered by the detection of a network configuration problem, as the addressing of the non-AP stations. This event may happen particularly in the context of high-density when a non-AP station enters a network cell. In such a context, in order to manage all non-AP stations, the AP may need to update the configuration of non-AP stations of its network cell.

In a variant, these steps may be performed at detection of other events, for instance:.

In a variant, these steps may be performed regularly, e.g., the AP regularly sends an update information in order to ensure that all stations use the same values of parameters.

Next, at step <NUM>, the AP generates a broadcast WUR Wake-Up frame as described with reference to <FIG>. More specifically, the Type subfield <NUM> of its Frame control field <NUM> is set to <NUM>, and its Address field <NUM> is set to its Transmit ID.

Next, at step <NUM>, the AP sends the Broadcast WUR Wake-Up frame generated at step <NUM> through the WUR module. On one hand, this broadcast WUR Wake-Up frame will be ignored by the awake non-AP stations. On the other hand, this broadcast WUR Wake-Up frame will Wake-Up all stations in doze mode. All non-AP stations of the wireless communication system <NUM> are awake at the end of this step.

At step <NUM>, the AP generates a Broadcast PCR frame including the broadcast update information (to be sent).

At step <NUM>, the AP sends the Broadcast PCR frame generated at step <NUM> through its PCR module. It can be received by all the non-AP stations as they are all awake.

According to a second embodiment shown in <FIG>, the AP sends the broadcast update information separately through its PCR and WUR modules.

First, at step <NUM>, the AP generates a broadcast WUR frame including the broadcast update information.

At step <NUM>, the AP sends the broadcast WUR frame generated at step <NUM> through its WUR. This broadcast WUR frame (and consequently the broadcast update information) can be received by all non-AP stations in doze mode and ignored by the others (excepted if the WUR is always ON in the non-AP station). Next, steps <NUM> and <NUM> of <FIG> are performed, so that the broadcast PCR frame (and consequently the broadcast update information) can be received by all awake non-AP stations and ignored by the others.

The order of the steps can be different. In a variant, the order may be the following: step <NUM>, step <NUM>, step <NUM> and next step <NUM>.

Moreover, in case of the WUR module of the non-AP station is always ON, steps <NUM> and <NUM> are not necessary.

According to an embodiment, the broadcast update information indicates a new value for a given WUR parameter applicable for all non-AP stations using their WUR module. For instance, it may concern a parameter necessary to support a WUR operation such as the Minimum Wake-Up Duration, the Duty Cycle Period Units (i.e. period for which the WUR non-AP station is able to receive WUR frames when WUR is ON), the WUR Operating Class (a WUR operating class corresponds to all available frequency bands and channels that can be used for transmission of WUR frame from the WUR AP to the WUR non-AP STA), the WUR Channel or the WUR Beacon. Such an update may be necessary when the WUR environment changes, such as the number of associated non-AP stations (which changes over time) or/and the wireless environment (more or less noisy). Moreover, it may concern a modification of the WUR identifiers as described with reference to <FIG>.

According to another embodiment, the broadcast update information indicates a new value for a given WLAN parameter necessary for all non-AP stations. For instance, the AP may change its width of the High Throughput operation channel or/and its channel frequency or/and its ack policy or/and QoS parameters, depending on the number of associated non-AP stations (which changes over time) or/and the wireless environment (more or less noisy) or/and the traffic (data rate, Qos type, uplink/downlink).

In an embodiment, the WUR module and the <NUM>. 11ax modules are using a same channel. In that case, if a WUR action frame requesting an update of parameters such as 'operating class' or 'channel parameters' is sent by the PCR (e.g., through <NUM> network), the AP will also have to send this update at the WUR module of each non-AP station.

<FIG> including <FIG>, illustrates, using flowcharts, steps of communication methods during which a WUR identifier modification is signaled by an AP to the non-AP stations of its network cell according to embodiments of the invention.

In these embodiments, a new value of the Transmit ID is required.

In these embodiments, the broadcast update information concerns the modification of the WUR identifiers of the non-AP stations.

It is recalled that within the wireless communication system <NUM>, some non-AP stations are awake and others are in doze mode. When a non-AP station is in doze mode, it is not able to receive PCR frames but it is able to receive WUR frames from AP. When a non-AP station is not in doze mode, i.e. it is awake, it is able to receive PCR frames and in some cases, it may be able to receive WUR frames.

According to a first embodiment shown in <FIG>, the AP wakes up all non-AP stations in doze mode through its WUR module and sends them a WUR identifier modification information through its PCR module (inside a PCR frame).

At step <NUM>, the AP receives a message indicating that a collision occurred and that a WUR identifiers modification may be necessary, the AP may select a new WUR identifier (for instance a new Transmit ID) and signal it to all its stations. This in this case, the event detected at step <NUM> is the reception of the message indicating the collision.

In another embodiment, the algorithm here described may be launched when the AP receives an unexpected PCR frame. Such a case may occur when a non-AP station receives a Wake-Up WUR frame and processes it by error. For instance, it may happen when the Wake-Up WUR frame comprises some erroneous bits and nevertheless, its address field (read at step <NUM> of <FIG>) corresponds to the Transmit ID, group ID in which the non-AP station is registered, or the Wake-Up ID of the non-AP station and the received FCS corresponds to the computed FCS (output of step <NUM> is yes).

At step <NUM>, the AP determines a WUR identifier modification information.

In an embodiment, the WUR identifier modification information is directly a new value of the Transmit ID. For instance, this new value can be selected randomly among a value range between <NUM> and <NUM> excluding the Wake-Up ID of the non-AP stations already assigned by the AP.

In another embodiment, the WUR identifier modification information corresponds to an identifier of a hash function to be applied to compute the FCS. A WUR identifiers hash function is a function which may compute a value of Transmit ID on <NUM> bits from a BSSID coded on <NUM> bits. In this case, the hash function is a fingerprint function.

The AP and non-AP stations may store (in the random access memory <NUM>) a predetermined list of WUR identifiers hash functions they can implement. For instance, a fingerprint function may be the <NUM> first (or last) bits of the BSSID of the AP. It may be also based on XOR. For instance, it may be equal to BSSID[<NUM>: <NUM>] XOR BSSID[<NUM>: <NUM>] XOR BSSID[<NUM>: <NUM>] XOR BSSID[<NUM>: <NUM>], BSSID[k,l] corresponding to the (l-k) bits of the BSSID of the AP between the kth bit and the lth bit. it may be equal to BSSID[<NUM>: <NUM>] XOR BSSID[<NUM>: <NUM>], BSSID[k,l] corresponding to the (l-k) bits of the BSSID of the AP between the kth bit and the lth bit.

One may note that the predetermined list of WUR identifiers hash functions is preferably the same between the AP and all non-AP stations. Similarly, the hash identifiers may correspond to the same WUR identifiers hash functions.

Next, at step <NUM>, the AP generates a broadcast WUR Wake-Up frame as described with reference to <FIG>. More specifically, the Type subfield <NUM> of its Frame control field <NUM> is set to <NUM>, and its Address field <NUM> is set to its current Transmit ID. One should note that the Address field <NUM> is not set to the Transmit ID determined at step <NUM>.

At step <NUM>, the AP sends the Broadcast WUR Wake-Up frame generated at step <NUM> through the WUR module. On one hand, this broadcast WUR Wake-Up frame may be ignored by the awake non-AP station. On the other hand, this broadcast WUR Wake-Up frame may Wake-Up all stations in doze mode. Hence, all non-AP stations of the wireless communication system <NUM> are awake at the end of this step.

At step <NUM>, the AP generates a Broadcast PCR frame including the broadcast update information (to be sent). To do so, the AP generates a WUR Action frame as described with reference to <FIG>. Its Action Type field <NUM> is assigned according to the table <NUM> described with reference to <FIG> and is set to <NUM> corresponding to "WUR identifiers collision identification response". Moreover, the WUR Action frame comprises a WUR Parameters field <NUM> assigned according to the table <NUM>.

According to embodiments of the invention, if WUR identifier modification information corresponds to a new value of a Transmit ID to be applied, the WUR Parameters field <NUM> comprises a subfield "Transmit ID" <NUM> corresponding to the value of the New Transmit ID to be applied.

According to embodiments of the invention, if WUR identifier modification information corresponds to a new value of a hash identifier to be applied, the WUR Parameters field <NUM> comprises a subfield "Hash Identifier" <NUM> corresponding to the value of the New Hash Identifier to be applied.

At step <NUM>, the AP sends the Broadcast PCR frame generated at step <NUM> through the PCR module. It may be received by all non-AP stations of the BSS because they are all awake at the end of step <NUM>. Each non-AP station will decode the Broadcast PCR frame.

According to some embodiments of the invention, if the WUR identifier modification information corresponds to a new value of a Transmit ID to be applied, it will store directly the new received Transmit ID which be applied from now by AP (for instance for transmitting broadcast Wake-Up frames).

According to other embodiments of the invention, if WUR identifier modification information corresponds to a new value of a hash identifier to be applied, it needs to recover the WUR identifiers hash function corresponding to the received hash identifier and computes the new Transmit ID to be applied from the BSSID and the recovered WUR identifiers hash function.

According to a second embodiment shown in <FIG>, the AP sends the broadcast update information separately through the PCR and WUR modules.

A key advantage of this second embodiment is that the multicast update information is received by all stations regardless of their states. In particular, it is not necessary for a given non-AP station to wait for its Wake-Up for receiving the multicast update information. In other words, in case a non-AP station is in doze mode while receiving the update information, it will process it when it will Wake-Up. A further exchange of messages is not necessary once the non-AP station is awake.

Steps <NUM>, <NUM>, <NUM> and <NUM> are the same as in the first embodiment of <FIG>.

After step <NUM>, the AP generates a broadcast WUR frame at step <NUM> that includes the WUR identifier modification information.

In a first example, the broadcast WUR frame corresponds to a WUR beacon frame with a dedicated <NUM>-bit field included in the Frame Control field <NUM> to indicate that the beacon frame corresponds also to WUR identifier modification information. More specifically, the dedicated <NUM>-bit field may be included in the Reserved field <NUM> of the Frame Control field <NUM>. According to a first implementation, the WUR identifier modification information may be comprised in the Reserved field <NUM> of the Frame Control field <NUM>. According to a second implementation, the WUR identifier modification information may be comprised in the payload field <NUM> of the WUR beacon frame.

In a second example, the broadcast WUR frame corresponds to a new type of WUR frame. More precisely, the Type subfield <NUM> of its Frame control field <NUM> is assigned according to the table <NUM> and is set to value <NUM> corresponding to a "WUR Broadcast Identifiers modification". Moreover, its Address field <NUM> is set to its current Transmit ID. One should note that the Address field <NUM> is not set to the Transmit ID determined at step <NUM>. The WUR identifier modification information is comprised in the payload field <NUM> of the broadcast WUR frame.

At step <NUM>, the AP sends the broadcast WUR frame generated at step <NUM> through the WUR module. This broadcast WUR frame (and consequently the broadcast update information) may be received by all non-AP stations in doze mode and ignored by the others excepted by non-AP station which WUR module is always ON.

Next, the steps <NUM> and <NUM> of <FIG> are performed.

The order of the steps can be different. For example, the order of steps may be the following: step <NUM>, <NUM>, step <NUM>, step <NUM> and next step <NUM>.

<FIG> illustrates, using a flowchart, steps of a communication method during which update information is signaled by an AP to a given non-AP station according to embodiments of the invention.

A key advantage of these embodiments is that the unicast update information is received regardless of the non-AP station is in doze mode or awake. In particular, it is not necessary for a non-AP station to wait for its wake-up for receiving the unicast update information.

At step <NUM>, the AP detects an event indicating that an update information needs to be sent to a given non-AP station of its network cell.

Such an event may be triggered by a modification of the network conditions, e.g., a degradation of the QoS, which may depend on environmental factors (e.g., weather conditions), the presence of physical objects, electrical and/or radio frequency interferences, the arrival/exit of a non-AP station in the network cell, or the distance increase between the AP and the given non-AP station.

Such an event may also be triggered by the detection of a network configuration problem, such as the addressing of the given non-AP station.

Next, at step <NUM>, the AP determines the state of a non-AP station (hereafter referred to as the targeted non-AP station): either in doze mode or awake.

If the targeted non-AP station is awake (output of <NUM> is yes), the next step is <NUM>. If not, the next step is <NUM>.

At step <NUM>, the AP generates a unicast WUR frame including the unicast update information. Next, at step <NUM>, the AP sends the unicast WUR frame through its WUR module which can be received by the targeted non-AP station because its WUR is ON.

At step <NUM>, the AP generates a unicast PCR frame including the unicast update information. Next, at step <NUM>, the AP sends the unicast PCR frame through its PCR module which can be received by the targeted non-AP station because its PCR is ON.

Moreover, in case of the WUR module of the non-AP station is always ON, only the steps <NUM> and <NUM> may be implemented.

According to an embodiment, the unicast update information may indicate a new value for a given WUR parameter necessary for a specific non-AP station using its WUR module. For instance, duty cycle (period for which the WUR non-AP station is able to receive WUR frames when WUR is ON) parameters as the starting point, the ON duration and duty cycle duration.

According to another embodiment, the unicast update information may indicate a new value for a given WLAN parameter necessary for all non-AP stations. It can be relevant in order to advantage or penalize a specific non-AP station by modifying for instance its QoS parameters (EDCA parameters). Moreover according to the wireless environment (more or less noisy), some parameters as modulation and coding scheme can be modified in order to adapt and reliable very quickly the transmission in order to receive/transmit data.

Moreover, it may concern a modification of the WUR identifiers as Wake-Up ID as described with reference to <FIG>.

According to another embodiment, the unicast update information indicates a new value for a given WLAN parameter of a specific non-AP station. For instance, it may concern any parameters defined in <NUM> for supporting a transmission such as the Modulation and Coding Scheme (MCS), the RTS Threshold, the Short Retry Limit, the OCWmin, or the Number of trigger frames per TBTT.

<FIG> illustrates, using a flowchart, steps of a communication method during which update information is signaled by an AP to a given non-AP station according to a variant of <FIG>.

According to this variant, if it is determined that the targeted non-AP station is not awake at step <NUM>, the AP generates a unicast WUR Wake-Up frame (Type subfield <NUM> of its Frame control field <NUM> set to <NUM> and Address field <NUM> set to Wake-Up ID of the non-AP station) at step <NUM>.

Next, the AP sends the unicast WUR Wake-Up frame to the targeted non-AP station.

Steps <NUM> and <NUM> are then performed as described with reference to <FIG>.

This alternative may be particularly interesting when the AP does not know the state of the non-AP station.

<FIG> illustrates, using a flowchart, steps of a communication method during which a WUR identifier modification is signaled by an AP to a given non-AP station according to embodiments of the invention. In these embodiments, a new value of the Wake-Up ID is required by the non-AP station.

In these embodiments, the update information concerns the modification of the WUR identifier of the non-AP station.

At a first step <NUM>, the AP receives a frame from a non-AP station (hereafter referred to as the targeted non-AP station) indicating that a collision between WUR identifiers occurred.

In another embodiment of the invention, the algorithm here described may be launched when the AP receives an unexpected PCR frame. Such a case may occur when a non-AP station receives a Wake-Up WUR frame and processes it by error. For instance, it may happen when the Wake-Up WUR frame comprises some erroneous bits and nevertheless, its address field (read at step <NUM> of <FIG>) corresponds to the Transmit ID or Group ID in which the non-AP station is registered, or the Wake-Up ID of the non-AP station and the received FCS corresponds to the computed FCS (output of step <NUM> is yes).

At step <NUM>, the AP determines the WUR identifier modification information. In this example, the WUR identifier modification information is directly a new value of the Wake-Up ID. For instance, this new value can be selected randomly among a value range between <NUM> and <NUM> excluding the Wake-Up ID of the non-AP stations already assigned by the AP and the Transmit ID of the AP.

Next, at step <NUM>, the AP determines the state of the targeted non-AP station: either in doze mode or awake.

At step <NUM>, the AP generates a unicast WUR frame including the WUR identifier modification information. The unicast WUR frame corresponds to a new type of WUR frame. More precisely the Type subfield <NUM> of its Frame control field <NUM> may be assigned according to the table <NUM> and may be set to value <NUM> corresponding to a "WUR Unicast Identifiers modification". Moreover, its Address field <NUM> may be set to its current Wake-Up ID and not the Wake-Up ID determined at step <NUM>. The WUR identifier modification information may be comprised in the payload field <NUM> of the unicast WUR frame.

At next step <NUM>, the AP sends the generated unicast WUR frame through the WUR module and this frame may be received by the targeted non-AP station because its WUR is ON.

At step <NUM>, the AP generates a unicast PCR frame including the WUR identifier modification information. To do so, the AP generates a WUR Action frame as described with reference to <FIG>. Its Action Type field <NUM> may be assigned according to the table <NUM> described with reference to <FIG> and may be set to <NUM> corresponding to "WUR identifiers collision identification response". Moreover, the WUR Action frame may comprise a WUR Parameters field <NUM> assigned according to the table <NUM>. According to embodiments of the invention, if WUR identifier modification information corresponds to a new value of a Wake-Up ID to be applied, the WUR Parameters field <NUM> may comprise a subfield "Wake-Up ID" <NUM> corresponding to the value of the Wake-Up ID to be applied.

At next step <NUM>, the AP sends the generated unicast PCR frame through the PCR which may be received by the targeted non-AP station because its PCR is ON.

In the case of the WUR module of the non-AP station is always ON, only the steps <NUM> may be implemented.

Many further modifications and variations will suggest themselves to those versed in the art upon making reference to the foregoing illustrative embodiments, which are given by way of example only and which are not intended to limit the scope of the invention, that being determined solely by the appended claims. In particular the different features from different embodiments may be interchanged, where appropriate.

Claim 1:
A communication method in a wireless communication network comprising at least one network cell, each cell comprising at least one station managed by an access point (AP), the method comprising, at the access point:
transmitting (<NUM>, <NUM>) a Wake-Up radio (WUR) frame to at least one station of the network cell of the access point;
transmitting (<NUM>, <NUM>) a main radio frame including update information, the main radio frame being transmitted to at least one station of the network cell of the access point,
wherein the main radio frame is a main radio broadcast frame transmitted to all the stations of the network cell of the access point that are awake and
wherein the WUR frame includes said update information and is sent to all the stations of the network cell of the access point that are in doze mode without waking-up them.