Patent Description:
In a wireless network, an AP can send a message targeted to multiple recipient wireless devices. This form of communication can include a broadcast of the message (which is targeted at all wireless devices within range of the AP or that satisfies some other condition) or a multicast of the message (which is targeted at wireless devices within a specified group regardless of whether they are in range of the AP). Broadcast and multicast transmissions can more generally be referred to as "group-addressed transmissions", where the "group" of wireless devices targeted can be all wireless devices within range of the transmitting device or that satisfies some other condition, or a group that is associated with a specified address (e.g., a multicast address). Controlling group-addressed transmissions in a WLAN can be associated with various challenges.

The present invention is as defined in the appended set of claims.

In a wireless local area network (WLAN), wireless devices may communicate with one another. A wireless device can include an endpoint device or a wireless access point (AP). A wireless AP (or more simply, an AP) can refer to a communication device to which a wireless device can establish a wireless connection to communicate with other endpoint devices. WLANs can include wireless networks that operate according to the Institute of Electrical and Electronic Engineers (IEEE) <NUM> or Wi-Fi Alliance Specifications.

Examples of endpoint devices include stations (STAs), access points (APs), computers (e.g., tablet computers, notebook computers, desktop computers, server computers, etc.), handheld devices (e.g. smart phones, personal digital assistants, etc.), wearable devices (smart watches, electronic eyeglasses, head-mounted devices, etc.), game appliances, health monitors, vehicles (or equipment in vehicles), cargo transportation units (e.g., trailers, containers, etc.), Internet of Things (IoT) devices, roadside units (RSUs) (such as devices in traffic lights, traffic signs, etc., that are able to transmit information to vehicles or other devices), storage devices, communication nodes, or other types of endpoint or user devices that are able to communicate wirelessly. Endpoint devices can include mobile devices and/or fixed position devices. More generally, an endpoint device can refer to an electronic device that is able to communicate wirelessly.

An IEEE <NUM> Broadcast Services (BCS) task group (IEEE <NUM>. 11bc) is working to improve the efficiency and applicability of broadcast services. The broadcasting or multicasting of information according to "broadcast services" refers to broadcasting or multicasting information that may be different from control information used for associating a device with a network or establishing a connection with a network. For example, broadcasting or multicasting of information according to "broadcast services" can refer to broadcasting or multicasting data, such as user data, application program data, vehicle-related data (e.g., data relating to vehicles, vehicular traffic, road conditions, etc.), and/or other types of data.

The following are some examples of broadcast services.

A downstream broadcast service involves a source wireless device (e.g., an AP or another wireless device) broadcasting or multicasting information to any device capable of receiving the information. The information may be secured, so that only devices with an established security association to the source wireless device can correctly decode the information. Security association is established when a device has successfully authenticated and has been authorized to communicate. Example use cases of downstream broadcast services include any or some combination of the following: live streaming of data, advertisements (such as of services or products or other information), billboards, emergency information, and so forth.

A vehicular broadcast service involves a source wireless device (e.g., a roadside unit or RSU, a vehicle, or other wireless device) broadcasting or multicasting information to any device capable of receiving the information. The vehicular broadcast service differs from the downstream broadcast service in that either the source or receiving wireless device may be moving at high speed relative to each other. Example use cases include any or some combination of advanced railroad grade crossing, broadcast of traveler information, and so forth.

An uplink broadcast service involves a source wireless device (e.g., a sensor or other wireless device) broadcasting or multicasting information (in an uplink) to any device capable of receiving the information. The uplink broadcast service differs from the downstream broadcast service or the vehicular broadcast service as the source wireless device may be a transmit-only device and have restricted capabilities (e.g., the source wireless device can include an IoT device, etc.). Example use cases include transmission of sensor data and so forth.

In a WLAN according to IEEE <NUM>, association between a wireless device and the WLAN refers to the establishment of a connection between the wireless device and another wireless device (e.g., an AP) that already has a connection to the WLAN. A "pre-associated state" of a wireless device refers to a state of the wireless device before the wireless device has established a connection with a WLAN. This state is also referred to as the unauthenticated, unassociated state or State <NUM>.

Other states defined by IEEE <NUM> include an authenticated, unassociated state (State <NUM>), an authenticated, associated state, but pending Robust Security Network (RSN) authentication (State <NUM>), and an authenticated, associated with RSN association established state (State <NUM>).

As used here, the broadcasting or multicasting of data can normally be referred to as group-addressed communications of group-addressed data. A "group" of wireless devices targeted in group-addressed communications can be all wireless devices within range of the transmitting device or that satisfy some other condition, or a group that is associated with a specified address (e.g., a multicast address).

Group-addressed transmissions in a WLAN can be associated with various issues. For example, traditional techniques or systems cannot address how transmission of group-addressed data can be performed in relation to unassociated wireless devices. Having a wireless device perform association with a WLAN so that transmissions of group-addressed data can occur can be inefficient, since it can take a relatively long time to perform the association, and the association can involve an exchange of a number of messages between the wireless device and the WLAN, which can take up communication resources.

Another issue relates to sending group-addressed data to a wireless device that is in a power-save mode (also referred to as a "doze state" or a "sleep state"). In the power-save mode, various components of the wireless device are powered off to reduce power consumption at the wireless device as compared to when the components are powered on. In some cases, if no differentiation is made between broadcast data and multicast data, a wireless device that is operating in a power-save mode may be signaled to wake up to receive multicast data that is not targeted to the wireless device. This results in wasted power consumption of the wireless device in waking up from the power-save mode to receive multicast data that the wireless device then determines is not targeted to the wireless device.

In some cases, when there are wireless devices in a power-save mode belonging to a Basic Service Set (BSS) of an AP, the AP may cache (or store) group-addressed data that are targeted to the wireless devices in the power-save mode, and can later deliver the data in a unicast transmission to each of the wireless devices as the wireless device transition out of the power-save mode. A BSS typically refers to a group of wireless devices associated with one another, where one wireless device is an AP. If there are a large number of wireless devices, sending data in unicast transmissions can lead to replication of a large number of data frames to be transmitted in unicast transmissions to the corresponding wireless devices. Such unicast transmissions can be inefficient.

A further issue relates to security of group-addressed data. In some examples, security in a BSS provides an encryption key (or more simply, a "key") for encrypting a data frame, where the key is based on a pairwise association between a wireless device and another wireless device (e.g., an AP). A group key can also be defined for group-addressed data frames in the BSS, where the group key is shared among all wireless devices in the WLAN. However, defining a group key that is shared by all wireless devices in the WLAN does not provide flexibility in cases where multiple keys may have to be used for different streams of group-addressed data or different groups of wireless devices.

<FIG> is a block diagram of an example network arrangement that includes a WLAN <NUM>. The WLAN <NUM> includes one or more APs <NUM> with which one or more endpoint devices <NUM> are able to wirelessly communicate. The WLAN <NUM> can include multiple APs, and there may be multiple endpoint devices to communicate with the one or more APs of the WLAN <NUM>.

In some examples according to <FIG>, the AP <NUM> can be a source wireless device that is able to broadcast or multicast information (in a group-addressed transmission <NUM>) according to a broadcast service, and the endpoint device <NUM> can be a recipient wireless device to receive broadcast or multicast information according to the broadcast service. In other examples, the endpoint device <NUM> can be a source wireless device that can send broadcast or multicast information (in a group-addressed transmission <NUM>) according to a broadcast service to one or more recipient wireless devices.

In further examples, another wireless device (not shown) can be coupled to the WLAN <NUM> that can act as a source wireless device or a recipient wireless device to communicate group-addressed data according to a broadcast service with either the endpoint device <NUM> or the AP <NUM>.

More generally, a "wireless device" can refer to either an endpoint device or an AP. A wireless device can perform group-addressed transmission of group-addressed data to other wireless devices.

As shown in <FIG>, the endpoint device <NUM> includes a group-addressed transmission control engine <NUM> that is able to control the communication of group-addressed data. Similarly, the AP <NUM> includes a group-addressed transmission control engine <NUM> that is able to control the transmission of group-addressed data.

As used here, an "engine" can refer to a hardware processing circuit, which can include any or some combination of a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, a digital signal processor, or another hardware processing circuit. Alternatively, an "engine" can refer to a combination of a hardware processing circuit and machine-readable instructions (software and/or firmware) executable on the hardware processing circuit.

In some examples, as shown in <FIG>, a wireless endpoint device <NUM>, such as a non-AP station (STA), can perform group-addressed transmissions <NUM> to one or more other wireless devices <NUM> that are part of a network infrastructure (e.g., the WLAN <NUM>). The "network infrastructure" can include an AP or another wireless device that is part of a network. In some examples, the wireless device that performs group-addressed transmissions can include a sensor device, an RSU, a vehicle, or any other type of wireless device. In some cases, it is desired that the wireless device performs the group-addressed transmissions while the wireless device is in the unassociated state (State <NUM> of IEEE <NUM> as discussed above). Thus, a source wireless device can send a group-addressed transmission to one or more other recipient wireless devices that are within range of the source wireless device.

In examples where the endpoint device <NUM> includes sensor data to send, the sensor data can be encoded and transmitted to devices (e.g., monitoring devices) that subscribe to a stream of the sensor data. A "stream" refers to a flow of data that is separately identifiable. In some examples, the stream can be sent in an Outside the Context of a BSS (OCB) mode or an Independent BSS (IBSS) mode.

The OCB mode is defined by IEEE <NUM>. The OCB can be used within <NUM> and <NUM> megahertz (MHz) wide channels in the <NUM> gigahertz (GHz) band for a vehicular environment. No authentication or association between the endpoint device <NUM> and an AP has to be performed for communications between the endpoint device <NUM> and the AP <NUM>. In OCB operation the AP (<NUM>) is treated as a peer STA. A parameter to be configured is the channel (central frequency and bandwidth) to communicate on, which can be configured beforehand.

An enhanced OCB mode is also being defined by IEEE <NUM>. This may allow operation of enhanced OCB devices outside of the <NUM> band (e.g., in the rest of the <NUM> band) and also provide the ability to use other channel bandwidths, apart from <NUM> and <NUM>.

In other examples, the endpoint device <NUM> can be operated in an IBSS mode. An IBSS refers to an ad-hoc network that is without an AP. In IBSS mode, a source IBSS wireless device can perform a group-addressed transmission to one or more other IBSS wireless devices.

<FIG> is a message flow diagram of an example process performed between the endpoint device <NUM> (that supports the signaling depicted in <FIG>) and the AP <NUM> (to allow the endpoint device <NUM> to start a group-addressed transmission of data). Note that the AP <NUM> may already have be involved in receiving group-addressed transmissions from one or more other wireless devices, some of which may not support the signaling depicted in <FIG>. Although <FIG> shows the AP <NUM> as being a recipient wireless device for the receipt of group-addressed data from the endpoint device <NUM>, it is noted that in other examples, other wireless devices can receive the group-addressed data from the endpoint device <NUM>. Such other wireless devices can receive the group-addressed data directly from the endpoint device <NUM>, or the other wireless devices can receive the group-addressed data forwarded by the AP <NUM> after the AP <NUM> has received the group-addressed data from the endpoint device <NUM>.

To start the group-addressed transmission, the endpoint device <NUM> sends (at <NUM>) a Broadcast Request message. The Broadcast Request message is broadcast by the endpoint device <NUM> for receipt by any APs within the range of the endpoint device <NUM>. The Broadcast Request message may be sent by the group-addressed transmission control engine <NUM> (<FIG>), for example. In the OCB case, the Broadcast Request message can be sent to another endpoint device instead of an AP.

The Broadcast Request message is sent with a group-addressed destination address and a group-addressed BSS identity (BSSID), for indicating that a group-addressed transmission is requested by the endpoint device <NUM>. The message contains information about the stream or streams the device is advertising to send in a group-addressed transmission. A "stream" refers to a flow of data that is separately identifiable. The sending of the Broadcast Request message is an example of how a wireless device can subscribe to one or more streams that are sent in group-addressed transmission(s).

Optionally the content/payload of the Broadcast Request message is secured (encrypted or signed) using keys set ahead of time. The signing and/or encrypting can be based on IEEE <NUM> certificates, such as IEEE <NUM> certificates. Examples of information in the Broadcast Request message can include metadata such as any or some combination of the following: a stream identifier (e.g., a name, identifier, or address to identify a stream), stream channel number (to identify a channel in which the stream is communicated), a stream camera angle (indicating an angle of a camera in examples where the endpoint device <NUM> is a camera), a video resolution and/or frame rate (in examples where the endpoint device <NUM> is a camera), an audio/video encoding bitrate in examples where the endpoint device <NUM> captures audio and/or video), a track number (to identify a track in examples where data is sent in multiple tracks), and so forth.

In response to the Broadcast Request message, the group-addressed transmission control engine <NUM> in the AP <NUM> sends (at <NUM>) a Broadcast Response message. The Broadcast Response message is a unicast message sent by the AP <NUM> (or another wireless device) that received the Broadcast Request message from the endpoint device <NUM>. The Broadcast Response message <NUM> is directed at the endpoint device <NUM>.

The Broadcast Response message includes an accept or reject indication. In the case where the Broadcast Request message identified multiple streams of group-addressed data, the Broadcast Response message can contain one or more stream indications (e.g., information elements, etc.) to indicate which one or more of the streams the recipient wireless device (the AP <NUM> in the example of <FIG>) has chosen to receive. The Broadcast Response message may contain a time limit indication (a time duration or end time) during which the recipient wireless device has chosen to receive the stream(s) of group-addressed data.

In response to receiving the Broadcast Response message, and assuming that the Broadcast Response message accepted the transmission of one or more streams of group-addressed data, the endpoint device <NUM> sends (at <NUM>), in an uplink, one or more group-addressed transmissions of the stream(s) chosen by the AP <NUM> as indicated by the one or more stream indications in the Broadcast Response message.

In some examples, the group-addressed data is not acknowledged by the AP <NUM> (or other recipient wireless device). Note that the group-addressed transmissions (<NUM>) can be periodic transmissions (transmitted every regular time period) or intermittent transmissions (transmitted when triggered by an event, such as a temperature going outside a specified range, etc.).

Each group-addressed transmission (<NUM>) can include one or more group-addressed frames (e.g., a data frame and/or a management frame). In each data frame, a destination address is set to a multicast address or broadcast address.

For communication while the sender wireless device (e.g., <NUM>) is in the unassociated state, the following three addresses in a header of a frame are set: a source address, which can be a source MAC address, of the sender wireless device; a destination address, which can be a group address (broadcast or multicast address representing a group-addressed stream); and a group-addressed BSSID set to a specified value, such as FF-FF-FF-FF-FE (or another address with an I/G bit set to G).

A recipient wireless device can choose to process a received frame as a broadcast or multicast stream based on all three of the addresses above, or just a subset.

As an example, the endpoint device <NUM> can include a temperature sensor, a pressure sensor, and a humidity sensor. Temperature data from the temperature sensor is to be sent in a temperature data stream, pressure data from the pressure sensor is to be sent in a pressure data stream, and humidity data from the humidity sensor is to be sent in a humidity data stream (three streams in this example). The Broadcast Request message includes information about the three streams. The Broadcast Response message indicates which of the three streams the AP <NUM> has chosen to receive.

The group-addressed transmission control engine <NUM> of the endpoint device <NUM> can consider the selection of which streams were selected by the AP <NUM> for receipt when the group-addressed transmission control engine <NUM> decides which streams to start sending. Note that there may be more than one recipient wireless device for the streams within the broadcast service area (BSA), such that the group-addressed transmission control engine <NUM> can take into account Broadcast Response messages from more than one recipient wireless device when deciding which streams to transmit. For example, recipient wireless device <NUM> may choose stream <NUM> but not streams <NUM> and <NUM>, but recipient <NUM> may choose streams <NUM> and <NUM> but not stream <NUM>. In such examples, the group-addressed transmission control engine <NUM> can decide to transmit streams <NUM> and <NUM>, but not stream <NUM>.

Note that the device (e.g., the AP <NUM> in <FIG>) that receives the Broadcast Request message may not be the endpoint of a stream of data. The AP <NUM> may forward the stream of data to another entity in the network. The IEEE <NUM> three address format may include a destination address that exists elsewhere behind the AP <NUM> in the LAN/WLAN. In such examples, the AP <NUM> can rebroadcast or re-multicast the data frames of a stream on the entire LAN, or the AP <NUM> may unicast the data frames of the stream to Internet Group Management Protocol (IGMP)-snooped recipient(s) wireless devices.

At some point, the AP <NUM> (the recipient wireless device) (or another wireless coupled to the AP <NUM>) may decide that the AP <NUM> wishes to stop receiving group-addressed data. The AP <NUM> sends (at <NUM>) a Broadcast Stop Request message to the endpoint device <NUM>. The Broadcast Stop Request message can be a unicast message individually addressed to the endpoint device <NUM>.

The Broadcast Stop Request message may indicate the specific one or more streams to cease transmitting. This may be identified by a stream identifier, such as a group-addressed MAC address, a group-addressed IP address, or another identity. The endpoint device <NUM> considers the information in the Broadcast Stop Request message when deciding whether or not to stop the group-addressed transmission of a given stream. If for example there are multiple recipient wireless devices of a stream, the group-addressed transmission control engine <NUM> of the endpoint device <NUM> may continue to transmit the stream even though one of the recipient wireless devices sent a Broadcast Stop Request message to stop the stream.

In response to the Broadcast Stop Request message, the group-addressed transmission control engine <NUM> of the endpoint device <NUM> sends (at <NUM>) a Broadcast Stop Response message to acknowledge the receipt of the Broadcast Stop Request message. The Broadcast Stop Response message is unicast to the AP <NUM>. In alternative implementations, the endpoint device <NUM> may send the Broadcast Stop Request message to the AP <NUM>, requesting the AP <NUM> to stop the group-addressed transmission of a given stream. The AP <NUM> would then transmit a Broadcast Stop Response message to the endpoint device <NUM> to acknowledge the receipt of the Broadcast Stop Request message.

<FIG> shows an example where in-band control signaling (i.e., control signaling exchanged over a channel of the WLAN <NUM>) is exchanged between the endpoint device <NUM> and the AP <NUM> (in the form of the messages <NUM>, <NUM>, <NUM>, and <NUM>) for controlling the group-addressed transmission of data. In other examples, the exchange of messages for controlling the group-addressed transmission of data can be negotiated out-of-band, i.e., over a communication link that is separate from the WLAN <NUM>. The control messages that are exchanged can establish channel information, a data rate, and a scheduling of the group-addressed transmission of data. There can also be a subscription process where one or more recipient wireless devices, such as the AP <NUM>, are configured with traffic characteristics and sensor information.

In some examples, security (privacy, trust, integrity) can be implemented by provisioning a security association. A mechanism can be provided for a recipient wireless device to subscribe to a sender wireless device to receive group-addressed transmissions. Alternatively, key distribution an encryption key for encrypting group-addressed data can be performed using an out-of-band mechanism (e.g., through a higher layer protocol). In this case, the higher layer protocol negotiates the key and once a key is agreed by the sender and recipient wireless devices, encryption at layer <NUM> (L2) can be used.

In further examples, as shown in <FIG>, network infrastructure equipment, such as the AP <NUM>, can transmit group-addressed data (in <NUM>) in a downlink to one or more recipient wireless devices (e.g., STAs <NUM>, one of which can be the endpoint device <NUM>), such as one or more associated wireless devices (e.g., wireless devices in State <NUM> as discussed above) or unassociated wireless devices (e.g., wireless devices in State <NUM> that is in the same BSA as the AP).

<FIG> is a message flow diagram of a process between the endpoint device <NUM> and the AP <NUM>. The message flow diagram of <FIG> includes a discovery phase <NUM>, a subscription/control phase <NUM>, and a broadcast phase <NUM>. In the discovery phase <NUM>, the AP <NUM> can advertise that the AP <NUM> has data to send in group-addressed transmission(s) according to broadcast services. The discovery phase <NUM> can use techniques as described in U. Application No. <NUM>/<NUM>,<NUM>, entitled "Indicating Support for a Broadcast Service," filed September <NUM>, <NUM>.

In some examples, in the discovery phase <NUM>, the AP <NUM> that is provisioned with the ability to send group-addressed transmission(s) sends an indication of support for a broadcast service(s). The indication of support for broadcast service(s) (hereinafter "broadcast service indication") can be in the form of an information element (e.g., a multi-bit field or a single bit) advertising that the source wireless device (e.g., the endpoint device <NUM> or the AP <NUM>) can provide a broadcast service (or multiple broadcast services).

The broadcast service indication can be included in any of various different messages. For example, the broadcast service indication can be included in a beacon that is transmitted by the AP <NUM> for receipt by multiple wireless devices within a wireless range of the AP. A beacon from an AP can include a Service Set Identifier (SSID) of the AP, to identify the WLAN <NUM>. The beacon can also include other information, which according to some implementations of the present disclosure include the broadcast service indication. A beacon is a type of an IEEE <NUM> management frame. In other examples, another type of an IEEE <NUM> management frame can be used to carry the broadcast service indication.

In other examples, the broadcast service indication can be included in a response message, such as a Probe response message, an Access Network Query Protocol (ANQP) response message, and so forth.

A Probe response according to IEEE <NUM> is a response to a Probe request sent by the endpoint device (e.g., <NUM> in <FIG>). A Probe request can be transmitted by an endpoint device for receipt by one or more APs within the range of the wireless device. The Probe request is used by the endpoint device to discover AP(s) within the wireless communication range of the endpoint device.

ANQP is a type of an advertisement protocol. ANQP operates as a simple request and response protocol that is used by a device to discover a range of information from an "Access Network" (AN) server. This AN server is either co-located with an AP or is located within a LAN, which is the layer <NUM> network to which the AP is connected. ANQP allows a device to determine the properties of the LAN before starting an association procedure.

In other examples, the broadcast service indication sent can be included in another message.

In addition, as part of the discovery phase <NUM>, the recipient wireless device (which in this case is the endpoint device <NUM>) can send a request to the AP <NUM> requesting information of further details (e.g., characteristics and/or state) of a broadcast service(s), and in response, the AP <NUM> responds with a response containing the requested information. Examples of information included in the response can include any or some combination of the following: a number of stream(s) the source wireless device has available to send in group-addressed transmissions, channels (or sub-channels) on which the stream(s) is (are) broadcast, time and availability of the stream(s), whether security is provided on the stream(s), and so forth.

The subscription/control phase <NUM> can include control messages exchanged between the endpoint device <NUM> and the AP <NUM> to control the group-addressed transmission of data.

In the subscription/control phase <NUM>, the group-addressed transmission control engine <NUM> in the endpoint device <NUM> can send (at <NUM>) a Broadcast Inquiry Request message to the AP <NUM>. The Broadcast Inquiry Request message can be sent as a unicast message, and includes information indicating that the endpoint device <NUM> is interested in group-addressed data transmitted by the AP <NUM> (or another device coupled to the AP <NUM>). In addition, the Broadcast Inquiry Request message can include identifier(s) of stream(s) of the group-addressed data that the endpoint device <NUM> is interested in. The Broadcast Inquiry Request message is an example of how a wireless device can subscribe to a stream.

In the subscription/control phase <NUM>, the group-addressed transmission control engine <NUM> in the AP <NUM> responds to the Broadcast Inquiry Request message by sending (at <NUM>), as a unicast message, a Broadcast Inquiry Response message.

The subscription/control phase <NUM> includes control messages exchanged between the endpoint device <NUM> and the AP <NUM> to control the group-addressed transmission of data.

The Broadcast Inquiry Response message can include information useable by the endpoint device <NUM> in receiving a group-addressed transmission from the AP <NUM>. For example, Broadcast Inquiry Response message can include an Orthogonal Frequency-Division Multiple Access (OFDMA) resource unit (RU), a channel, a secondary channel, or other transmission resource to use for the group-addressed transmission. The AP <NUM> may provide OFDMA resource allocation such that some RUs are used for group-addressed transmissions, and other RUs are used for unicast transmissions. A wireless device may receive group-addressed data frames and unicast data frames, from different source addresses in the WLAN <NUM>, on different subchannels (or RUs) simultaneously. This type of multiple access is enabled by the OFDMA capabilities in IEEE <NUM>. 11ax, for example.

Further, the Broadcast Inquiry Response message can include a Multicast Group Temporal Key (MGTK) specific to a stream that the endpoint device <NUM> is.

In the subscription/control phase <NUM>, a recipient wireless device can also request the stopping of a stream. In such cases, the group-addressed transmission control engine <NUM> of the AP <NUM> can make a determination of whether or not to stop the stream. For example, the AP <NUM> (or another wireless device) may be transmitting the stream to other recipient wireless devices; in such a scenario, the AP <NUM> (or another wireless device) can continue to perform the group-addressed transmission of the stream so regardless of the stop request, if one or more (e.g., a threshold number of) other wireless devices are subscribed to the stream.

The control messages exchanged in the subscription/control phase <NUM> can include Generic Advertisement Service (GAS) or ANQP request and response messages (according to IEEE <NUM>. 11aq) or other types of messages (in state <NUM> or <NUM>). In some examples, the control messages can include Current Traffic Specification (TSPEC) information, which allows one wireless device to signal its traffic requirement to another wireless device.

In further examples, Internet Group Management Protocol (IGMP) snooping allows a network infrastructure (e.g., an AP or another network device) to determine that a wireless device (e.g., the endpoint device <NUM>) is interested in group-addressed data. IGMP snooping can be used at the AP <NUM> to manage the list of streams (as group addresses in use) and the wireless devices subscribed to those streams.

Once the subscription/control phase <NUM> is performed, the AP <NUM> can broadcast data in the broadcast phase <NUM>. In the broadcast phase <NUM>, the AP <NUM> (or another wireless device coupled to the AP <NUM>) sends (at <NUM>) group-addressed transmissions to the endpoint device <NUM>.

Each stream that is sent in a group-addressed transmission can include streaming data, such as audio, video, or sensor data. The stream can be transmitted periodically from the AP <NUM> to wireless device(s) that subscribe(s) to the stream, or can be transmitted intermittently in response to an event.

Each group-addressed transmission from the AP <NUM> includes one or more frames (data frame and/or management frame), which can be sent to a wireless device in State <NUM> or State <NUM>. A value of one or more of the addresses in the three address MAC header of each frame may correspond to the multicast or broadcast destination address of the stream. The frames may be transmitted in a particular resource unit (RU) of an IEEE <NUM>. 11ax OFDMA transmission, for example. A stream may be transmitted in a channel adjacent to another channel used for unicast data. Alternatively, a dedicated subchannel (e.g., an OFDMA RU) can be used to carry the stream.

For a wireless device in State <NUM>, the determination of whether a received frame is part of a stream starts by checking the <NUM> addresses, and whether the BSSID matches the multicast address of a particular stream.

Communication bandwidth depends on the type of stream. The AP <NUM> may allocate RU sizes based on requirements of the stream.

The transmission of frames of a stream may be synchronized with a power save state such as Traffic indication map/Delivery traffic indicaiton map (TIM/DTIM) periods or target wake time (TWT) periods. This may be communicated from to the receiving device such that it can optimize the power saving of its receiver hardware.

TIM/DTIM periods are periods that define a general time for a wireless device to be in a power-save mode or be awake. Therefore if the transmission of group-addressed data from an AP is synchronised based on the TIM/DTIM transmissions from the same AP, then the recipient wireless device may be be awake to receive the group-addressed data. TWT periods define when a wireless device is to wake up to receive data.

Security in a BSS can use an encryption key for encrypting a data frame. The key can include a group key. In IEEE <NUM>-<NUM>, a Group Temporal Key (GTK) that is distributed by an AP has a key identifier (Key ID) of <NUM> or <NUM> and is applied to all group-addressed data.

In accordance with some implementations of the present disclosure, multiple group keys can be used for different streams of group-addressed data or different groups of wireless devices. Such a group key can be referred to as a Multicast GTK (MGTK). One or more MGTKs can be defined. In such implementations, the IEEE <NUM>-<NUM> GTK can be referred to as a Broadcast GTK (BGTK).

To enable MGTK, a new Authentication and Key Management (AKM) (or set of AKMs) is defined that support BGTK and MGTK. Support for the new AKM or set of AKMs can be negotiated between the AP <NUM> and the wireless devices during the association process. When using this new AKM instead of previously defined AKM a larger number of Key IDs are enabled as described later.

The AP <NUM> maintains a mapping between the MGTK, a group-addressed stream, and a set of wireless devices subscribed to the group-addressed stream. Each group of wireless devices (referred to as an "MGTK group") that employ a particular MGTK is assigned a respective identifier (referred to as an "MGTK identifier"). Different groups of wireless devices that employ respective different MTGKs are assigned different identifiers.

The AP <NUM> may advertise one or more group-addressed streams in beacons, Probe responses, or other messages or information elements. This advertisement includes information about the MGTK to use for each stream.

After a wireless device has subscribed to a group-addressed stream, the AP <NUM> assigns the wireless device to an MGTK group and transmits the MGTK to the wireless device in a GTK handshake exchange.

The endpoint device <NUM> and/or the AP <NUM> can each advertise support for MGTK. For example, support for MGTK can be advertised as a service or an element in an ANQP message or another type of message.

When the endpoint device <NUM> associates with the AP <NUM> according to some illustrative examples for better understanding the present invention which are not covered by the appended claims, the endpoint device <NUM> and the AP <NUM> can negotiate support for MGTK, such as by using a <NUM>-way handshake. For example, the negotiated MGTK can be indicated in a capability bit in a Robust Security Network Element (RSNE) in an association request, or can be included in a set of new AKM suites in the RSNE.

A control element to be modified is a Key Data Element (KDE), which can be modified as shown in <FIG>. The KDE of <FIG> includes a Key ID <NUM>, with both bits set to "<NUM>" to indicate use of MGTK. An MGTK Key ID <NUM> identifies an MGTK, and a GTK or MGTK field includes a GTK or an MGTK (MGTK if both bits of the Key ID <NUM> are set to "<NUM>"). Although example value and lengths are shown in <FIG>, it is noted that in other examples, other values and/or lengths can be used.

The AP and wireless device(s) store the MGTK. This multiplicity of Key IDs allows a larger number of Key IDs than just <NUM> and <NUM>. This then enables an AP to maintain the multiple groups/sets of devices with different MGTKs. The differentiating Key IDs also enables STAs to maintain keys of multiples of these groups simultaneously.

For an associated wireless device according to some illustrative examples for better understanding the present invention which are not covered by the appended claims, the capability of supporting more than one group key (GTK) in the BSS is exchanged at the time of association. Each group-addressed stream can be protected with a respective different group key (GTK). A group key (GTK) can include a BGTK or an MGTK (from among multiple MGTKs).

When the AP transmits a group-addressed stream, the AP encapsulates a frame using the MGTK. The encapsulation works in one of the following ways.

In an example, the AP uses a bit in a Counter Mode with Chaining Message Authentication Code Protocol/Galois Counter Mode Protocol (CCMP/GCMP) header <NUM> (<FIG>) to indicate that a stream is a group-addressed stream, and encapsulates each frame of the stream using the appropriate MGTK.

In another example, the AP indicates the MGTK Key ID in the CCMP/GCMP header of each frame transmitted to indicate the Key ID of the specific MGTK that the receiver should use to decode the data PDU carried in that frame. The CCMP/GCMP header <NUM> is included as part of a data frame (a CCMP MPDU). The CCMP/GCMP header <NUM> includes a reserved field <NUM>, an MGTK Key ID field <NUM> that includes an MGTK Key ID, an Ext IV field <NUM>, and a Key ID field <NUM> (which if set to a specified value, such as both bits "<NUM>" indicates that an MGTK Key ID is assigned in the header <NUM>).

When an associated wireless device receives a group-addressed frame for a stream that the wireless device has not subscribed to, the wireless device drops the frame based on its multicast address, or drops the frame for which the wireless device does not have an MGTK.

An AP assigning a singular GTK to a STA is accomplished during a <NUM>-way handshake once a pairwise transient key (PTK) is generated. In the case of assigning multiple GTK and MGTK this can be done in unicast messages from AP to.

<FIG> is a block diagram of a first wireless device <NUM> that is able to transmit or receive group-addressed data according to some examples. The first wireless device <NUM> can be the endpoint device <NUM> of <FIG>, for example.

The first wireless device <NUM> includes a communication interface <NUM> to communicate over a WLAN. The communication interface <NUM> includes a transceiver and a protocol stack including protocol layers that manage communication according to respective communication protocols.

The first wireless device <NUM> includes one or more hardware processors <NUM>. A hardware processor can include a microprocessor, a core of a multi-core microprocessor, a microcontroller, a programmable integrated circuit, a programmable gate array, a digital signal processor, or another hardware processing circuit.

The first wireless device <NUM> further includes a non-transitory machine-readable or computer-readable storage medium <NUM> storing machine-readable instructions that are executable on the one or more processors to perform respective tasks.

The machine-readable instructions can include group-addressed transmission control instructions <NUM> to manage communications of group-addressed data.

The group-addressed transmission control instructions <NUM> are executable to send, from the first wireless device <NUM> to a second wireless device (e.g., the AP <NUM>), a control indication that controls transmission of group-addressed data between the first wireless device and the second wireless device over the WLAN. For example, the control indication can include a start indication (e.g., the Broadcast Request message of <FIG>) to start a procedure for the first wireless device <NUM> to send group-addressed data (e.g., <NUM> in <FIG>).

As another example, the control indication can include another start indication (e.g., the Broadcast Inquiry Request message of <FIG>) to cause the second wireless device to transmit the group-addressed data to the first wireless device <NUM>.

In response to the control indication, the first wireless device <NUM> receives a response indication (e.g., the Broadcast Response message of <FIG> or the Broadcast Inquiry Response message of <FIG>) from the second wireless device regarding the transmission of the group-addressed data.

In examples where the first wireless device <NUM> is the sender of group-addressed data, the control indication identifies a plurality of streams of group-addressed data, and the response indication from the second wireless device identifies a subset of the plurality of streams of group-addressed data that the second wireless device has selected to receive. Further, the response indication can include timing information (e.g., the time limit indication discussed in the section "Group-addressed transmission start procedure" above) relating to a timing relating to when the second wireless device has chosen to receive the group-addressed data.

In some examples, the first wireless device <NUM> receives, from the second wireless device, a key for encrypting the group-addressed data, where the key is associated with a group of wireless devices, and where different groups of wireless devices are associated with different keys for data encryption. Further, the key is associated with a particular stream that includes the group-addressed data, and different streams of group-addressed data are associated with different keys for data encryption.

The storage medium <NUM> can include any or some combination of the following: a semiconductor memory device such as a dynamic or static random access memory (a DRAM or SRAM), an erasable and programmable read-only memory (EPROM), an electrically erasable and programmable read-only memory (EEPROM) and flash memory; a magnetic disk such as a fixed, floppy and removable disk; another magnetic medium including tape; an optical medium such and different streams of group-addressed data are associated with different keys for data encryption.

The storage medium <NUM> can include any or some combination of the following: a semiconductor memory device such as a dynamic or static random access memory (a DRAM or SRAM), an erasable and programmable read-only memory (EPROM), an electrically erasable and programmable read-only memory (EEPROM) and flash memory; a magnetic disk such as a fixed, floppy and removable disk; another magnetic medium including tape; an optical medium such as a compact disc (CD) or a digital video disc (DVD); or another type of storage device. Note that the instructions discussed above can be provided on one computer-readable or machine-readable storage medium, or alternatively, can be provided on multiple computer-readable or machine-readable storage media distributed in a large system having possibly plural nodes. Such computer-readable or machine-readable storage medium or media is (are) considered to be part of an article (or article of manufacture). The storage medium or media can be located either in the machine running the machine-readable instructions, or located at a remote site from which machine-readable instructions can be downloaded over a network for execution.

Claim 1:
A method comprising:
sending, by a first wireless device to a second wireless device, a control indication that controls transmission of group-addressed data between the first wireless device and the second wireless device over a wireless local area network, WLAN, characterised in that the second wireless device is an access point, AP; and
transmitting, by the first wireless device, the group-addressed data in an uplink to the AP while the first wireless device is in an unassociated state with respect to the AP, the unassociated state referring to a state of the first wireless device before establishing a connection with the WLAN.