Patent Description:
Mechanisms for narrowband multi-channel transmission for wakeup radio (WUR) operation are disclosed. A station (STA) may turn off its primary connectivity radio (PCR) and operate its WUR according to previously negotiated WUR operating parameters. The STA may monitor for WUR beacons and WUR frames over a first WUR channel. The STA may determine and set a wakeup reason to "the WUR channel may not support reliable transmission" based on the WUR not successfully receiving beacons within a first duration. The STA may turn off the WUR, and turn on the PCR to send a first short WUR frame including the wakeup reason, and receive a second short WUR frame with a WUR channel assignment. The STA may turn off the PCR, turn on the WUR, and monitor for WUR signals on a second WUR channel according to the WUR channel assignment and the previously negotiated WUR operating parameters.

For example, the communications systems <NUM> may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word discrete Fourier transform Spread OFDM (ZT-UW-DFT-S-OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), and the like.

As shown in <FIG>, the communications system <NUM> may include wireless/wired transmit/receive units (WTRUs) 102a, 102b, 102c, 102d, a radio access network (RAN) <NUM>, a core network (CN) <NUM>, a public switched telephone network (PSTN) <NUM>, the Internet <NUM>, and other networks <NUM>, though it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and/or network elements. By way of example, the WTRUs 102a, 102b, 102c, 102d, any of which may be referred to as a station (STA), may be configured to transmit and/or receive wireless signals and may include a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD), a vehicle, a drone, a medical device and applications (e.g., remote surgery), an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts), a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like.

Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN <NUM>, the Internet <NUM>, and/or the other networks <NUM>. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a NodeB, an eNode B (eNB), a Home Node B, a Home eNode B, a next generation NodeB, such as a gNode B (gNB), a new radio (NR) NodeB, a site controller, an access point (AP), a wireless router, and the like.

In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR Radio Access , which may establish the air interface <NUM> using NR.

The WTRU <NUM> may include a full duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for both the UL (e.g., for transmission) and DL (e.g., for reception) may be concurrent and/or simultaneous. In an embodiment, the WTRU <NUM> may include a half-duplex radio for which transmission and reception of some or all of the signals (e.g., associated with particular subframes for either the UL (e.g., for transmission) or the DL (e.g., for reception)).

The AP may have access or an interface to a Distribution System (DS) or another type of wired/wireless network that carries traffic in to and/or out of the BSS. 11e DLS or an <NUM>.

The primary channel may be a fixed width (e.g., <NUM> wide bandwidth) or a dynamically set width. In certain representative embodiments, Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) may be implemented, for example in <NUM> systems.

11af and <NUM>. 11af and <NUM>. 11n, and <NUM>. 11af supports <NUM>, <NUM>, and <NUM> bandwidths in the TV White Space (TVWS) spectrum, and <NUM>. 11ah may support Meter Type Control/Machine-Type Communications (MTC), such as MTC devices in a macro coverage area.

11n, <NUM>. 11ac, <NUM>. 11af, and <NUM>. If the primary channel is busy, for example, due to a STA (which supports only a <NUM> operating mode) transmitting to the AP, all available frequency bands may be considered busy even though a majority of the available frequency bands remain idle.

The WTRUs 102a, 102b, 102c may communicate with gNBs 180a, 180b, 180c using subframe or transmission time intervals (TTIs) of various or scalable lengths (e.g., containing a varying number of OFDM symbols and/or lasting varying lengths of absolute time).

For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, support for network slicing (e.g., handling of different protocol data unit (PDU) sessions with different requirements), selecting a particular SMF 183a, 183b, management of the registration area, termination of non-access stratum (NAS) signaling, mobility management, and the like. For example, different network slices may be established for different use cases such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for MTC access, and the like. The AMF 182a, 182b may provide a control plane function for switching between the RAN <NUM> and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and/or non-3GPP access technologies such as WiFi.

The IEEE <NUM> High Efficiency WLAN (HEW) Study Group (SG) was created to explore enhancements to the quality of service (QoS) experienced by different types of wireless users in many usage scenarios including high-density scenarios in the <NUM> and <NUM> bands. For example, the HEW SG may consider use cases that support dense deployments of APs, STAs, and associated radio resource management (RRM) technologies. Example applications for HEW may include usage scenarios such as data delivery for stadium events and other high user density scenarios (e.g., train stations, enterprise/retail environments), video delivery, and wireless services for medical applications.

The IEEE <NUM>. 11ax Task Group (TG) (TGax), approved by the HEW SG, has investigated and measured traffic for a variety use case scenarios and found that a variety of applications may have a high likelihood for short packets and certain network applications may generate short packets. Example of network applications that may generate short packets include, but are not limited to, the following applications: virtual office, transmit power control (TPC) acknowledgement (ACK), video streaming ACK, device/controller (e.g., mice, keyboards, game controls), access probe request/response, network selection probe requests and ANQP, and/or control frames for network management. 11ax standard may support multi-user (MU) features, such as uplink (UL) and/or downlink (DL) OFDMA and/or UL and/or DL MU-MIMO, that may benefit from UL multiplexing including UL random access multiplexing.

The IEEE <NUM>. 11ba Wake Up Radio (WUR) SG was created to explore and develop PHY and MAC protocols to provide enhanced low power operations of <NUM> devices. The operating frequency bands for <NUM>. 11ba WUR may include <NUM> and/or <NUM> and may be extended to sub <NUM>. In an example of <NUM>. 11ba WUR, an <NUM> device may be equipped with a WUR and a primary connectivity radio (PCR). APs and/or non-AP STAs may have a WUR as a companion radio to a PCR. The PCR may be used to transmit and receive regular <NUM> packets (e.g., in accordance with <NUM>. 11ac, <NUM>. 11af, <NUM>. 11ah, <NUM>. 11n, and/or <NUM>. 11ax) and the WUR may operate as a low-power companion radio to the PCR. The WUR may have a coverage range that is at least the same as the range of the PCR operating on at least a <NUM> payload bandwidth. Herein, PCR may be referred to interchangeably as the main radio, the primary radio, the <NUM> radio, the WiFi radio, or the primary transmission radio (PTR), and packet, frame, signal, signaling and message may be used interchangeably. Herein, sleep, doze or WUR mode (or state) may refer to the STA operating with its PCR turned off and/or its WUR turned on, such that less power is used to run the WUR than the PCR. A STA operating in WUR mode and receiving with the WUR a wakeup packet may trigger or cause the corresponding PCR to wake up from a sleep state and power on. Herein, specific types of interframe spacing (IFS) may be given as examples; however, any other type of IFS (e.g., reduced IFS (RIFS)) or any other time interval may be applied in the examples described herein.

In an example, the WUR may transmit and/or receive packets that carry control information. In an example, the WUR in a STA may be a one-directional radio that is configured to receive messages, such as messages containing control information. The WUR may communicate over a narrowband channel (i.e., with a narrow frequency bandwidth) and/or may have active receiver power consumption below <NUM> milliWatt (mW). In an example, an AP may operate on a <NUM> PCR channel, such that the <NUM> PCR channel may include (i.e., within the <NUM> frequency band) a <NUM> WUR channel allocated for WUR operation with a WUR-enabled WTRU(s). In another example, an AP may operate on a <NUM> PCR channel, such that the <NUM> PCR channel may include and it more than one non-overlapping <NUM> WUR channel allocated for WUR operation with a WUR-enabled WTRU(s). In another example, an AP may operate on a <NUM> PCR channel, such that each <NUM> PCR channel (within the <NUM> channel) may include a <NUM> WUR channel (for a total four <NUM> WUR channels) allocated for WUR operation with a WUR-enabled WTRU.

Example applications of <NUM>. 11ba WUR may include, but are not limited to, the following applications: loT devices, low power operation for smart phones, quick message/incoming call notification scenarios, quick status query/report applications, configuration change scenarios, and/or quick emergency/critical event report scenarios.

<FIG> is a signaling diagram of an example WUR negotiation procedure <NUM> between an AP <NUM> and a STA <NUM>, where the STA <NUM> is equipped with a WUR <NUM> and a PCR <NUM> (the STA <NUM> may include other components not shown, including any of the WTRU <NUM> components shown in <FIG>). The PCR <NUM> may include a transceiver and may be an <NUM> radio operating in accordance with <NUM> protocols such as <NUM>. 11n and/or <NUM>. The WUR <NUM> may include a transceiver or a receiver in the case that the WUR <NUM> is configured for communication in one direction (i.e., reception). Example scenarios in which a WUR negotiation procedure <NUM> may be performed include, but are not limited to, the following scenarios: frequency band and channel negotiation; STA identifier (ID) allocation in a wakeup packet; indication of required time for turning on the <NUM> radio (i.e., PCR <NUM>); and/or indication of periodic WUR <NUM> receiver on/off schedule. WUR mode field(s) or element(s) may be defined to provide information for WUR operation including, but not limited to, WUR setup information, WUR channel information, WUR identity (ID), WUR duty cycle, and time duration information for hopping or switching between the PCR <NUM> and the WUR <NUM>. The WUR mode field(s) carrying WUR information may be included in any of the WUR negotiation frames (e.g., WUR request frame <NUM>, WUR response frame <NUM>, WUR signaling frame <NUM>) and/or any other control or management frames (not shown), such as beacon frame, (re)association frames, and/or probe request/response frames.

The following time periods are shown in the example WUR negotiation procedure <NUM>: period <NUM> during which the WUR <NUM> is off and the PCR <NUM> is on; period <NUM> during which the STA <NUM> is in a low power or WUR mode where the WUR <NUM> is on and the PCR <NUM> is off; and period <NUM> during which the WUR <NUM> is off and the PCR <NUM> is on. During period <NUM>, the STA <NUM> may send, using PCR <NUM>, a WUR request message <NUM> to the AP <NUM>. The STA <NUM> may receive, with the PCR <NUM>, a WUR response message <NUM> from the AP <NUM> which may include an indication that the STA <NUM> is authorized to use WUR operating mode. The STA <NUM> may send, using PCR <NUM>, WUR signaling <NUM> (e.g., one or more messages) to the AP <NUM> to notify the AP <NUM> that the STA <NUM> is entering the WUR state and will be using WUR <NUM> and turning off PCR <NUM>. During period <NUM>, the STA <NUM> is in a low power WUR state such that PCR <NUM> is off and the STA <NUM> may communicate with the AP <NUM> using WUR <NUM>. In an example, the WUR <NUM> may operate in a one-directional mode such that the WUR <NUM> may receive packets from the AP <NUM> and may not be used to transmit packets. During period <NUM> while PCR <NUM> off, the STA <NUM> may receive, using the WUR <NUM>, a wakeup packet <NUM> from the AP <NUM> notifying the STA <NUM> to turn on PCR <NUM>. In response to the wakeup packet <NUM>, the STA <NUM> in period <NUM> may turn on PCR <NUM> (for example (e.g., after a processing delay <NUM>) and turn off WUR <NUM>. During period <NUM>, the STA <NUM> may exchange messages with the AP <NUM>. For example, the STA <NUM> may send, to the AP <NUM>, a power save poll (PS-Poll) and/or trigger frame(s) <NUM> and may receive, from the AP <NUM>, data frame(s) <NUM>.

In an example, a STA (e.g., AP or non-AP STA) that supports WUR may use the PCR to communicate <NUM> signals over a wideband channel(s) and use the WUR to communicate WUR signals over narrowband channel(s). For example, an <NUM> signal may have a bandwidth of <NUM>, <NUM>, <NUM>, <NUM>+<NUM>, and <NUM>. In contrast, the bandwidth of WUR signal may be <NUM> or <NUM>. The <NUM> signal may be transmitted on a wideband channel that may or may not partially overlap with a WUR transmission signal. In comparison to wideband transmission, narrowband transmission may be more vulnerable to channel fading. Thus, a STA that is experiencing deep channel fading may have difficulty receiving the WUR signal even if the STA is in a close proximity to the transmitting STA (e.g., AP). Accordingly, narrowband WUR transmissions may benefit from additional protection to channel fading.

In an example, WUR narrowband multi-channel transmission may be supported. For example, an AP may operate on one <NUM> wideband channel (e.g., a <NUM> channel) while supporting multiple non-overlapping narrowband WUR channels (e.g., <NUM> WUR channels at <NUM> each). An AP may use any of the following example methods to transmit multiple WUR signals on multiple WUR channels concurrently. In an example, one WUR channel (from among multiple concurrent WUR channels) may be defined as a WUR primary channel and WUR beacons/synchronization signals may be transmitted over the WUR primary channel. All the WUR STAs may monitor the WUR primary channel in order to receive the WUR beacons/synchronization signals. In another example, one WUR channel may be defined as a primary WUR channel and WUR beacons/synchronization signals may be transmitted some or all the WUR channels (i.e., not just the WUR primary channel). In another example, no WUR primary channel may be defined and WUR beacons/synchronization signals may be transmitted over any or all of the WUR channels.

<FIG> are signaling diagrams of example beacon/synchronization signaling procedures 300A and 300B with multiple WUR channels <NUM>, <NUM>, <NUM> and <NUM>. Example beacon/synchronization signaling procedures 300A and 300B may involve WUR beacon/synchronization signals transmitted on all WUR channels <NUM>-<NUM>. According to example synchronized beacon/synchronization signaling procedure 300A, WUR beacon/synchronization frames <NUM><NUM>. <NUM> may be transmitted concurrently on channels <NUM>-<NUM> in a synchronized format, and the WUR beacon interval <NUM> may be the same for all WUR channels <NUM>-<NUM>. According to example offset beacon/synchronization signaling procedure 300B, WUR beacon frames <NUM><NUM>. <NUM> may be transmitted on channels <NUM>-<NUM> with a fixed offset. For example, beacon/synchronization frame <NUM><NUM> on WUR channel <NUM> may be transmitted 1T offset duration after the transmission of beacon/synchronization frame <NUM><NUM> on WUR channel <NUM>. Beacon/synchronization frame <NUM><NUM> on WUR channel <NUM> may be transmitted 2T offset duration after the transmission of the beacon/synchronization frame <NUM><NUM> on WUR channel <NUM>. Beacon/synchronization frame <NUM><NUM> on WUR channel <NUM> may be transmitted 3T offset duration after the transmission of the beacon/synchronization frame <NUM><NUM> on WUR channel <NUM>. The WUR beacon intervals <NUM><NUM>. <NUM> may have the same duration on all WUR channels <NUM>-<NUM>.

According to an example, an AP may transmit beacon/synchronization frames over multiple channels (e.g., a WUR primary channel may or may not be used) and WUR channel switching or WUR channel hopping may be used during WUR operation. WUR channel switching may include the STA renegotiating WUR channels and/or WUR channel parameters with AP each time the STA switches WUR channels. For WUR channel hopping, the STA may change or hop between WUR channels according to a channel hopping pattern where the AP and STA already have information on the upcoming WUR channels. Examples of WUR channel switching and WUR channel hopping are described in detail below.

<FIG> is a signaling diagram of an example WUR channel switching procedure <NUM>. In the example of <FIG>, the AP <NUM> may transmit beacon/synchronization frames (not shown) over multiple WUR channels <NUM>-<NUM>, for example during a WUR channel setup period <NUM>, and/or during WUR channel monitoring periods <NUM> and <NUM>. The WUR channels <NUM>-<NUM> may or may not include a WUR primary channel. During the WUR channel setup period <NUM>, the AP <NUM> and the STA <NUM> may exchange WUR setup information (e.g., WUR beacon/synchronization signal information, WUR duty cycle information, WUR channel information, and/or WUR rate information).

A STA <NUM> may transmit, to its associated AP <NUM>, a WUR request frame <NUM> on a main channel <NUM> that may be associated with the main operation radio (e.g., PCR). The WUR request frame <NUM> may indicate the intent of STA <NUM> to enter a doze or sleep mode on the main channel <NUM> (i.e., by turning off the main radio/PCR) and to start monitoring at least one WUR channel <NUM>-<NUM> (using one or more WURs). In the WUR request frame <NUM>, the STA <NUM> may indicate a preferred WUR channel(s) among multiple WUR channels <NUM>-<NUM>. For example, the STA <NUM> may indicate to the AP <NUM> a preferred channel index, a WUR channel list in preference order, and/or a channel quality report for each WUR channel <NUM>-<NUM> in WUR request frame <NUM>. For example, the channel quality report may include signal-to-noise ratio (SNR), signal-to-interference-plus-noise ratio (SINR), or received signal strength indicator (RSSI) measured on each WUR channel. In an example, a main <NUM> channel (e.g., of <NUM>) may be composed of WUR channels <NUM>-<NUM>, such that measurements for each WUR channel <NUM>-<NUM> (e.g., <NUM> each with guard band removed) may be made using the main radio by measuring a signal transmitted on the main <NUM> channel comprising the WUR channels <NUM>-<NUM>.

The STA <NUM> may detect and receive a WUR response frame <NUM> from the AP <NUM> on the main channel <NUM> (over the main radio). In an example, the WUR response frame <NUM> may be received IFS (e.g., xIFS) time after the WUR request frame <NUM>. The WUR response frame <NUM> may indicate a WUR channel assigned to the STA <NUM> (e.g., WUR channel <NUM>). The WUR response frame <NUM> may indicate a WUR start time indicating the time the STA <NUM> may switch to the WUR (e.g., the time may be set to x_duration before a WUR beacon/synchronization frame, no shown, where x_duration may be a small duration to allow the STA <NUM> to switch from main radio to the WUR radio). The WUR response frame <NUM> may indicate other operating WUR channels by the AP <NUM> (e.g., any of WUR channels <NUM>-<NUM>).

The WUR response frame <NUM> may indicate a WUR beacon interval or synchronization signal periodicity. The WUR response frame <NUM> may indicate a maximum monitoring duration before the STA <NUM> switches WUR channels. For example, if the STA <NUM> does not observe any valid WUR transmission on the assigned WUR channel <NUM> during a maximum monitoring duration (e.g., equal to monitoring period <NUM>), then the STA <NUM> may try to switch to a different WUR channel (e.g., from WUR channel <NUM> to WUR channel <NUM>). In another example, the maximum monitoring duration before switching may be or predetermined and may not be signaled by the AP <NUM>. The WUR response frame <NUM> may indicate the maximum monitoring duration before the STA <NUM> switches back to the main radio (PCR)/main channel <NUM> from a WUR channel (e.g., WUR channel <NUM>). For example, if STA <NUM> does not observe any valid WUR transmission on WUR channel <NUM> during the maximum monitoring duration, the STA <NUM> may try to switch back to the main channel <NUM>/main radio. In another example, the maximum monitoring duration before switching may be or predetermined and may not be signaled by the AP <NUM>. The WUR response frame <NUM> may indicate the WUR STA ID (e.g., for WUR channel <NUM>) assigned to the STA <NUM>.

The STA <NUM> may transmit a WUR signaling frame <NUM> over the main channel <NUM>, which may indicate the reception of WUR Response frame <NUM> and may indicate that the STA <NUM> is switching from the main radio to the WUR after transmitting the WUR signaling frame <NUM>. In an example, The STA <NUM> may transmit the WUR signaling frame <NUM> an IFS time (e.g., yIFS) after the receiving the WUR response frame <NUM>. In an example not shown, the STA <NUM> may transmit the WUR signaling frame <NUM> in a separate transmission opportunity (TXOP) from the TXOP during which WUR request/response exchange (e.g., at a later time). The WUR signaling frame <NUM> may include an indication that the STA <NUM> will switch off the main radio from the end of the transmission of the WUR signaling frame <NUM>. The WUR signaling frame <NUM> may include an indication that the STA <NUM> will switch off the main radio at a time indicated by the AP <NUM> as the WUR start time. The WUR signaling frame <NUM> may include an indication for the STA <NUM> to switch on the WUR from the end of the WUR signaling frame <NUM> transmission. The WUR signaling frame <NUM> may include an indication for the STA <NUM> to switch off the main radio in the time indicated by the AP <NUM> as the WUR start time. The WUR signaling frame <NUM> may include the WUR channel index and/or the WUR channel ID of the channel that the STA <NUM> will be operating on (e.g., for WUR channel <NUM>).

Following the WUR signaling <NUM>, the STA <NUM> may switch on the WUR and/or switch off the main radio (e.g., from the end of WUR signaling frame <NUM> transmission or at a time indicated by the AP <NUM> as the WUR start time). The STA <NUM> may monitor <NUM> one or more assigned WUR channel(s) <NUM>-<NUM> (e.g., assigned WUR channel <NUM>). For example, the STA <NUM> may monitor <NUM> WUR channel <NUM> for a maximum monitoring duration. If the STA <NUM> does not observe any valid transmission from AP <NUM> during the maximum monitoring duration (e.g., AP <NUM> does not transmit a wakeup STA packet <NUM> during the maximum monitoring duration equal to the monitoring period <NUM>), the STA <NUM> may transmit a WUR switching frame <NUM> to switch to a different WUR channel (e.g., from WUR channel <NUM> to WUR channel <NUM>). The WUR switching frame <NUM> may carry the current WUR index/ID (e.g., for WUR channel <NUM>), and WUR index/ID to be used (e.g., for WUR channel <NUM>).

In order to transmit the WUR switching frame <NUM>, the STA <NUM> may turn on the main radio, and transmit the WUR switching frame <NUM> over the main radio/main channel <NUM> after monitoring the main channel <NUM> for a predetermined or time duration. The STA <NUM> may perform enhanced distributed channel access (EDCA) backoff before the main radio transmission of WUR switching frame <NUM>. In order to reduce the power consumption over the main radio, the STA <NUM> may use EDCA parameters of a higher priority access category to transmit WUR switching frame <NUM> over the main channel <NUM>. For example, the WUR switching frame <NUM> may be sent using a certain access category, such as AC_VI or AC_VO. The AP <NUM> may modify the EDCA access parameters by changing the EDCA parameter set element in a beacon frame, probe response frame, and (re)association response frame (not shown). In an example, the WUR switching frame <NUM> may be a WUR request frame. The STA <NUM> may wait for the AP <NUM> to respond with a WUR response frame <NUM> over the main channel <NUM>, and then transmit another WUR signaling frame <NUM>. The AP <NUM> and STA(s) <NUM> may use the WUR request and response frame exchange to negotiate the WUR channel to be used, such that the STA <NUM> may use the agreed upon WUR channel (e.g., WUR channel <NUM>).

In another example not shown, the STA <NUM> may determine the identity of the operating WUR channels from a previous WUR request/response frame exchange from which the STA <NUM> may determine the WUR channel (e.g., WUR channel <NUM> or <NUM>) the WTRU should use for monitoring and/or switching. The STA <NUM> may transmit information indicating the selected WUR channel(s) to the AP <NUM> over the main channel <NUM>. Then the STA <NUM> may switch to monitoring the WUR channel as selected and indicated by the STA <NUM>.

In another example not shown, the STA <NUM> may transmit the WUR switching frame <NUM> over a currently assigned WUR channel (e.g., WUR channel <NUM>) to the AP <NUM>. For example, the STA <NUM> may wait for the AP <NUM> to respond over the current WUR channel <NUM>. Then the STA <NUM> may switch to a new WUR channel (e.g., WUR channel <NUM>). In another example, the STA <NUM> may switch to a new WUR channel <NUM> after the STA <NUM> transmits the WUR switching frame <NUM> over the current WUR channel <NUM> prior to the switch. Once the STA <NUM> switches to the new WUR channel <NUM>, the STA <NUM> may transmit a WUR switching channel frame (not shown) over the new WUR channel <NUM> to inform the AP <NUM> about the WUR channel switch. The STA <NUM> may expect to receive a confirmation from the AP <NUM> on the new WUR channel <NUM>.

Once STA <NUM> completes the switch to WUR channel <NUM>, STA <NUM> may monitor <NUM> WUR channel <NUM> for a duration (e.g., the maximum monitoring duration) and may receive a wakeup STA frame <NUM> from the AP <NUM>, for example. In another example not shown, the STA <NUM> may continue monitoring the current WUR channel <NUM> without switching WUR channels even if no frames are received by the STA <NUM> while monitoring <NUM> WUR channel <NUM> for the maximum monitoring duration.

In an example of an AP-driven WUR trigger procedure, an AP may initiate a WUR request/response exchange with one or more STAs. For example, the AP trigger WUR mode when any one or more of the following conditions are met: when the AP determines that the STA(s) are capable of WUR transmission; when the AP determined that the STA(s) intend to switch to WUR mode of operation to save power; and/or when the AP does not have buffered data for the STA(s).

For an AP driven WUR trigger procedure, the AP may transmit a WUR Trigger frame to one or more STAs over the main radio. The WUR trigger frame may carry the WUR operation channels, WUR start time, and/or WUR channel assignment for the STA(s). The WUR trigger frame may be the same as the WUR response frame. On reception of the WUR trigger frame, a STA may check whether it is an intended recipient of the WUR trigger frame (e.g., if the STA is identified in the WUR trigger frame). If the STA is an intended recipient, then the STA may check whether it intends to turn on its WUR radio and/or switch off its main radio. The STA may transmit a WUR signaling frame (e.g., using a trigger based PPDU) if the WUR trigger frame is requested or allowed. In the case that the WUR trigger frame is transmitted to multiple STAs, multiple STAs may reply simultaneously using an OFDMA transmission. In each of the WUR signaling frames transmitted by the STA(s), the STA(s) may indicate whether it will switch off the main radio and/or start using the WUR. The WUR channel index on which the STA may monitor may be included in the WUR signaling frame. Other elements of an AP driven WUR trigger procedure may be similar to the elements for the WUR STA procedure, such as those elements described above and with respect to <FIG>.

In an example, WUR channel hopping may be used as part of WUR operation. <FIG> is a signaling diagram of an example WUR channel hopping procedure <NUM>. In the example WUR channel hopping procedure <NUM> of <FIG>, the AP <NUM> may transmit beacon/synchronization frames <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> over one or more WUR channels <NUM>, <NUM>, <NUM>, <NUM>. The WUR channels <NUM>, <NUM>, <NUM>, <NUM> may or may not include a primary channel. <FIG> shows a WUR beacon interval duration, TBI, and a WUR channel hopping duration, TCH, which may be the duration for a STA <NUM> to monitor a particular or assigned WUR channel. For example, the STA <NUM> may monitor WUR channel <NUM> from time T0 to time T0 + TCH and may monitory WUR channel <NUM> from time T0 + TCH to time T0 + 2TCH. The WUR channel hopping duration TCH may be in units of number of beacon interval durations TBI, for example.

WUR channel hopping intervals (His), HI <NUM> and HI <NUM>, may be defined as intervals between [t, t+T_CH], where t may be equal to a WUR start time (e.g., T0 for HI <NUM> WUR channel <NUM>), or an offset from the WUR start time (e.g., T0+TCH for HI <NUM> and WUR channel <NUM>). N may be an integer that represents the number of channel hops performed during the channel hopping interval HI <NUM>. TSW may be the switching time for the STA <NUM> to hop from one WUR channel to another WUR channel, and may be equal to or greater than <NUM>. In the case that extra signaling is transmitted to inform of the WUR channel switching, the signaling time may be included in the switching time TSW. In an example, the start time t for a WUR channel hopping interval HI may be generally defined by Equation <NUM>:
<MAT>.

<FIG> is a signaling diagram of an example WUR channel hopping procedure <NUM>. The AP <NUM> may transmit beacon/synchronization frames (not shown) over multiple WUR channels <NUM>-<NUM>, for example during a WUR channel setup period <NUM>. The WUR channels <NUM>-<NUM> may or may not include a WUR primary channel.

A STA <NUM> may transmit, to its associated AP <NUM>, a WUR request frame <NUM> on a main channel <NUM> that may be associated with the main operation radio (e.g., PCR). The WUR request frame <NUM> may indicate the intent of STA <NUM> to enter a doze mode on the main channel <NUM> (i.e., by turning off the main radio/PCR) and start monitoring at least one WUR channel <NUM>-<NUM> (using one or more WURs). In the WUR request frame <NUM>, the STA <NUM> may indicate a preferred WUR channel(s) among multiple WUR channels <NUM>-<NUM>. For example, the STA <NUM> may send a preferred channel index, a WUR channel list in preference order, and/or a channel quality report for each WUR channel <NUM>-<NUM>. The channel quality report may include SNR, SINR, or RSSI measured on each WUR channel <NUM>-<NUM>.

The STA <NUM> may detect and receive a WUR response frame <NUM> from the AP <NUM> on the main channel <NUM> (over the main radio). In an example, the WUR response frame <NUM> may be received an IFS (e.g., xIFS) time after the WUR request frame <NUM>. The WUR response frame <NUM> may indicate a WUR channel hopping pattern to the STA <NUM>. In an example, the first WUR channel in the WUR channel hopping pattern (e.g., WUR channel <NUM>) may be used for the STA <NUM> as the first WUR channel to monitor. The WUR channel hopping pattern may go through all the available WUR channels operated by the AP <NUM>. For example, the AP may operate four WUR channels <NUM>-<NUM>, and the hopping pattern may indicate the hopping order as [<NUM>, <NUM>, <NUM>, <NUM>]. In another example, the WUR channel hopping pattern may go through a selected subset of the WUR channels <NUM>-<NUM>. For example, the hopping pattern may be [<NUM>, <NUM>, <NUM>] such that WUR channel <NUM> may not be used by the STA <NUM>. The WUR channel down-selection may depend on the WUR channel quality report and user density on each WUR channel <NUM>-<NUM>. The WUR channel quality report may be explicitly provided to the AP <NUM> from the STA(s) <NUM> or may be implicitly acquired through bi-directional communication.

The WUR response frame <NUM> may indicate a starting WUR channel, which may be a field that indicates the WUR channel that the STA <NUM> switches to after the WUR request/response exchange between the AP <NUM> and the STA <NUM>. In an example, a starting WUR channel field may not be included in the WUR response frame <NUM> and the WUR starting channel may be determined from the WUR channel hopping pattern. The WUR response frame <NUM> may indicate a WUR hopping periodicity or WUR hopping duration (TCH). A WUR hopping periodicity or duration field may indicate the time duration for the STA <NUM> to monitor (remain on) a WUR channel. The WUR response frame <NUM> may indicate a WUR start time. A WUR start time field may indicate the time at which the STA <NUM> should switch to a WUR channel. For example, the WUR start time may be set to x_duration before a WUR beacon/synchronization frame, where x_duration may be a small duration to allow the STA <NUM> time to switch from the main radio to the WUR radio. The WUR response frame <NUM> may indicate the WUR beacon interval or synchronization signal periodicity (TBI). The WUR response frame <NUM> may indicate the maximum monitoring duration. The maximum monitoring duration field may be in units of beacon intervals (BI) or hopping intervals (HI). In an example, the maximum monitoring duration may be long enough to cover the channel hopping over all of the WUR channel candidates (e.g., WUR channels <NUM>-<NUM>). The WUR response frame <NUM> may indicate the WUR STA ID (e.g., for WUR channel <NUM>) assigned to the STA <NUM>.

The STA <NUM> may transmit a WUR signaling frame <NUM> over the main channel <NUM>, which may indicate the reception of WUR Response frame <NUM> and may indicate that the STA <NUM> is switching from the main radio to the WUR after transmitting the WUR signaling frame <NUM>. In an example, The STA <NUM> may transmit the WUR signaling frame <NUM> an IFS time (e.g., yIFS) after the receiving the WUR response frame <NUM>. In an example not shown, the STA <NUM> may transmit the WUR signaling frame <NUM> in a separate TXOP from the TXOP during which the WUR request frame <NUM> and WUR response exchange <NUM> are exchanged. The WUR signaling frame <NUM> may include an indication that the STA <NUM> will switch off the main radio from the end of the transmission of the WUR signaling frame <NUM>. The WUR signaling frame <NUM> may include an indication that the STA <NUM> will switch off the main radio at a time indicated by the AP <NUM> as the WUR start time. The WUR signaling frame <NUM> may include an indication for the STA <NUM> to switch on the WUR from the end of the WUR signaling frame <NUM> transmission. The WUR signaling frame <NUM> may include an indication for the STA <NUM> to switch off the main radio in the time indicated by the AP <NUM> as the WUR start time. The WUR signaling frame <NUM> may include the WUR channel index and/or the WUR channel ID of the channel that the STA <NUM> will operating on (e.g., for WUR channel <NUM>).

Following the WUR signaling <NUM>, the STA <NUM> may switch on the WUR and/or switch off the main radio (e.g., from the end of WUR signaling frame <NUM> transmission or at a time indicated by the AP <NUM> as the WUR start time). The STA <NUM> may monitor <NUM> the WUR channel on the WUR channel hopping list (e.g., WUR channel <NUM>) for the WUR HI <NUM>. If the STA <NUM> observes one or more WUR beacon/synchronization frames during the WUR HI <NUM>, the STA <NUM> may adjust its timer based on a timing synchronization function (TSF) or partial TSF defined in the WUR beacon/synchronization frames. If a WUR packet (e.g., a WUR beacon/synchronization frame) arrives during the boundary of two HI (e. g, HI <NUM> and HI <NUM>), the STA <NUM> may continue receiving the WUR packet over the WUR channel that it is currently monitoring (e.g., WUR channel <NUM>), and then switch to the next WUR channel (e.g., WUR channel <NUM> in HI <NUM>) after the reception of the WUR packet. This may cause a delay in channel hopping, however the delay may not impact the HI partition. In an example, the start time t for a WUR channel hopping interval HI (e.g., the start time for HI <NUM> and HI <NUM>) may be defined by Equation <NUM>.

In the example WUR channel hopping procedure <NUM>, the STA <NUM> may monitor WUR channel <NUM> during HI <NUM>, and then the STA <NUM> may hop to next WUR channel <NUM>, as defined by the WUR channel hopping pattern. Once STA <NUM> completes hopping to WUR channel <NUM>, STA <NUM> may monitor <NUM> WUR channel <NUM> for a duration HI <NUM> (e.g., which may be equal to the maximum monitoring duration) and may receive a wakeup STA frame <NUM> from the AP <NUM> during HI <NUM>. In an example, if the wakeup STA frame <NUM> is expected to cross the HI <NUM> time boundary, then the wakeup STA frame <NUM> may be truncated to fit in the current HI <NUM>. In an example not shown, if the STA <NUM> does not receive any valid transmissions during a maximum monitoring duration during HI <NUM>, the STA <NUM> may switch on its main radio and/or associate with a new AP that is different from AP <NUM>.

<FIG> is a signaling diagram of another example WUR channel hopping procedure <NUM>. The example WUR channel hopping procedure <NUM> may operate similarly to the example WUR channel hopping procedure <NUM>; in particular, WUR channel setup period <NUM>, the WUR request <NUM>/response <NUM> exchange, WUR signaling <NUM>, WUR channel monitoring <NUM> on WUR channel <NUM> for a duration/HI <NUM>, WUR channel monitoring <NUM> on WUR channel <NUM> for a duration/HI <NUM>, and AP <NUM> sending wakeup STA packet <NUM> to STA <NUM> may be similar to the equivalent signaling and monitoring described in example WUR channel hopping procedure <NUM> of <FIG>. However, the example WUR channel hopping procedure <NUM> of <FIG> may further include a step where the STA <NUM> may switch to the main radio and main channel <NUM> in between HI <NUM> and HI <NUM> in order to transmit WUR switching signaling <NUM> and then switch back to the next WUR channel <NUM>. For example, the WUR switching signal <NUM> may include the STA ID for the STA <NUM> that is switching its WUR channel, and/or may indicate the next WUR channel (e.g., WUR channel <NUM>) for STA <NUM>. In an example not shown, the STA <NUM> may transmit WUR switching signaling <NUM> over the WUR channel <NUM> used during the last time slot in the HI <NUM>. In another example not shown, the STA <NUM> may switch to the next WUR channel <NUM> to transmit the WUR switching signal <NUM> over the next WUR channel <NUM> at the beginning of the next HI <NUM>.

In both WUR channel hopping procedure <NUM> and <NUM> of <FIG> and <FIG>, a STA-driven WUR request/response exchange is shown, however an AP-driven WUR negotiation exchange, as disclosed herein, may also be used. For WUR channel hopping and retransmission, an AP may transmit a WUR packet on one of the WUR channels to a STA. If the AP determines that the WUR packet transmission was not successful, it may hold the WUR packet retransmission and wait for channel hopping before retransmitting the packet. The AP may perform WUR retransmission after the STA hops to another WUR channel.

Example WUR transmission procedures may employ a primary WUR channel. For example, the primary WUR channel may be defined or selected from among the available WUR channels and beacon/synchronization signals may be transmitted over the primary WUR channel. <FIG> is a signaling diagram of an example WUR transmission procedure <NUM> with a WUR channel <NUM> functioning as a primary channel. The WUR transmission procedure <NUM> may begin with the STA <NUM> transmitting a WUR request frame <NUM> on the main operation radio and main channel <NUM> to its associated AP <NUM> to indicate the STA's <NUM> intent to go into doze mode on the main channel <NUM> (i.e., by turning off the main radio PCR) and start monitoring at on at least one WUR channel <NUM>-<NUM>. The WUR request frame <NUM> may indicate the STA's <NUM> preference from among multiple WUR channels <NUM>-<NUM>. For example, the STA <NUM> may send the preferred WUR channel index, a WUR channel list in preference order, and/or a channel quality report for each WUR channel <NUM>-<NUM>. The channel quality may be SNR, SINR, and/or RSSI measured from each WUR (e.g., on the primary channel).

The STA <NUM> may detect and receive a WUR response frame <NUM> from the AP <NUM> on the main channel <NUM> (over the main radio). In an example, the WUR response frame <NUM> may be received an IFS (e.g., xIFS) time after the WUR request frame <NUM>. The WUR response frame <NUM> may indicate a primary WUR channel (e.g., WUR channel <NUM>), for example by WUR channel index or WUR channel ID. The WUR response frame <NUM> may indicate to the STA <NUM> any one or more of the following information: an assigned WUR channel (e.g., WUR channel <NUM>); a WUR Start time indicating the time the STA <NUM> may switch to the WUR (e.g., x_duration before WUR beacon/synchronization frame, where x_duration may be a small duration to allow the STA <NUM> to switch from main radio to WUR radio); other operating WUR channels; WUR beacon interval or synchronization signal periodicity; and/or the maximum monitoring duration before the STA <NUM> goes back to the main radio. For the maximum monitoring direction, if the STA <NUM> does not observe any valid WUR transmission during the maximum monitoring duration, the STA <NUM> may try to switch back to the main radio (PCR). The maximum monitoring duration may be or predetermined and may not be signaled by the AP <NUM>.

The STA <NUM> may transmit a WUR signaling frame <NUM> over the main channel <NUM>, which may indicate the reception of WUR Response frame <NUM> and may indicate that the STA <NUM> is switching from the main radio to the WUR after transmitting the WUR signaling frame <NUM>. In an example, The STA <NUM> may transmit the WUR signaling frame <NUM> a certain number of IFS time after the receiving the WUR response frame <NUM>. In an example not shown, the STA <NUM> may transmit the WUR signaling frame <NUM> in a separate TXOP from the WUR request/response exchange TXOP. The WUR signaling frame <NUM> may include an indication that the STA <NUM> will switch off the main radio from the end of the transmission of the WUR signaling frame <NUM>. The WUR signaling frame <NUM> may include an indication that the STA <NUM> will switch off the main radio at a time indicated by the AP <NUM> as the WUR start time. The WUR signaling frame <NUM> may include an indication for the STA <NUM> to switch on the WUR from the end of the WUR signaling frame <NUM> transmission. The WUR signaling frame <NUM> may include an indication for the STA <NUM> to switch off the main radio in the time indicated by the AP <NUM> as the WUR start time. The WUR signaling frame <NUM> may include the WUR channel index and/or the WUR channel ID of the channel that the STA <NUM> will be operating on (e.g., for WUR channel <NUM>).

Following the WUR signaling <NUM>, the STA <NUM> may switch on the WUR and/or switch off the main radio (e.g., from the end of WUR signaling frame <NUM> transmission or at a time indicated by the AP <NUM> as the WUR start time). The STA <NUM> may monitor <NUM> the WUR primary channel <NUM>. After detecting a beacon/synchronization signal <NUM> transmitted over WUR primary channel <NUM>, the STA <NUM> may determine a WUR group (e.g., from a WUR channel allocation element or field that may have been provided in beacon/synchronization signal <NUM> or WUR response frame <NUM>). The STA <NUM> may determine its allocated WUR channel(s) (e.g., WUR channel <NUM>) by checking the element/field in the beacon/synchronization signal <NUM> and/or the WUR response frame <NUM> that contains a STA ID to WUR channel index (or ID) mapping. After determining the assigned WUR channel <NUM>, the STA <NUM> may monitor <NUM> the assigned WUR channel <NUM> after reception of the WUR beacon/synchronization signal <NUM>.

The STA <NUM> may switch back to the WUR primary channel <NUM> for x_duration before the boundary of WUR BI <NUM>. The STA <NUM> may monitor <NUM> the WUR primary channel <NUM> and detect a beacon/synchronization signal <NUM> transmitted over WUR primary channel <NUM>. The STA <NUM> may determine its allocated WUR channel(s) (e.g., WUR channel <NUM>) by checking the element/field (e.g., in beacon/synchronization signal <NUM> and/or <NUM>) that contains the STA ID to WUR channel index (or ID) mapping. After determining the next assigned WUR channel <NUM>, the STA <NUM> may monitor <NUM> the assigned WUR channel <NUM> after reception of the WUR beacon/synchronization signal <NUM>, and may receive a wakeup STA frame <NUM> from the AP <NUM> during BI <NUM>. In an example not shown, if the STA <NUM> does not observe a WUR beacon/synchronization signal over the primary WUR channel <NUM> during the maximum monitoring duration/BI <NUM>, the STA <NUM> may switch back to the main radio. The STA <NUM> may retransmit a WUR report frame, which may indicate that the STA <NUM> failed to receive a WUR beacon/synchronization signal over the current primary WUR channel <NUM>. In another example not shown, WUR channel assignment for STA <NUM> may be performed using WUR setup (re)negotiation over the main channel <NUM>, such that the STA <NUM> may monitor for WUR beacons/synchronization signals over the primary WUR channel <NUM> to confirm connectivity and acquire timing information.

In an example, the WUR transmission may involve a subset of WUR channels from among a larger set of possible resource units (RUs) and/or subchannels. An AP may define a subset of RUs (and/or subchannels) as the WUR channels for the BSS (which may be referred to as the WUR BSS) of the AP. For example, a subset of the RUs in the primary channel of the AP's BSS may be defined as the set of WUR channels for the AP's BSS. In another example, a subset of RUs (and/or subchannels) of the AP's operating channels may be considered as the set of WUR channels for the BSS. The subset of RUs and/or subchannels may be chosen to minimize correlated fading on each of WUR channel. For example, if a WUR channel is <NUM> wide, then subchannel <NUM> and subchannel <NUM> in the primary <NUM> channel may be considered as the set of WUR channels for the BSS. In another example, subchannel <NUM>, subchannel <NUM>, channel <NUM>, and channel <NUM> in the primary <NUM> channel may be considered as the set of WUR channels for the BSS. In an example, the set of WUR channels may be indicated by the AP to the STA using a bitmap. In an example, the indication of the set of WUR channels may further include an indication a WUR channel width, and/or an indication of the starting frequency or offset in reference to the primary channel.

The indication of the set of WUR channels may be included in an information element (IE), for example in a management, control, data, extension, or null data packet (NDP) frame. For example, the WUR channel set indication may be provided in (short) beacon frames, probe response frames, (re)association response frames, an/or fast initial link setup (FILS) discovery frames. The WUR channel set indication may be included in wakeup STA request and/or wakeup STA response frames.

The WUR channel set indication and WUR channel change procedure may include an AP determining the WUR channel set and including one or more subchannels/RUs (e.g., from the AP's primary channel(s) and/or its operating channels) in the WUR channel set. For example, the AP may indicate to a STA(s) the WUR channel set in (short) beacon, probe response, (re)association response, and/or fast initial link setup (FILS) discovery frames. The STA may send to the AP a WUR request frame prior to the STA going to sleep (i.e., powering off its PCR and turning on its WUR). The WUR request frame may include a set of one or more preferred WUR channels for the STA. The preferred WUR channel set may be determined based on the WUR channel set advertised by the AP and may be a subset of the WUR channel set. In an example, the preferred WUR channel set sent by the STA may include a preference index based on measurements (e.g., SNR, SINR, RSSI) made by the STA on the WUR channels.

The WUR channel change procedure may include the AP, after receiving the preferred WUR channel set from the STA, responding to the STA with a WUR response frame. The WUR response frame may include a preferred WUR channel set that may or may not be the same as the preferred WUR channel set sent by the STA. After receiving the WUR response frame, the STA may go into a doze state (turn off PCR, turn on WUR) and may monitor one or more of the agreed WUR channel set(s). For example, the STA may only monitor the preferred WUR channel set, which may be agreed on by the AP and the STA, or indicated by the AP. The AP may transmit WUR beacon/synchronization signals regularly on one or more of the WUR channels in the WUR channel set(s) that the AP advertised to and/or agreed on with the STA(s) associated with the AP that are currently monitoring the WUR channels. The AP may transmit WUR beacon/synchronization signals on all WUR channels (e.g., subchannels) that are part of the advertised or agreed WUR channel set(s). These transmission of WUR beacon/synchronization signals by the AP may be concurrent or staggered.

The WUR channel change procedure may include a STA, after having not detected any WUR beacon/synchronization signals for a predetermined interval of time (e.g., a Max_Missed_WUR_Beacon_Interval duration), may switch to a next preferred WUR channel (e.g., subchannel) in the agreed WUR channel set. If the STA detects a WUR beacon/synchronization signal on the current WUR channel within the predetermined interval, then the STA may continue to monitor the same WUR channel. The STA may send a WUR packet and/or a PCR packet to alert the AP of its new WUR channel. A WUR packet may simply include a WUR channel index and an identifier of the STA and the identifier for the AP for this purpose. If a WUR beacon/synchronization signal cannot be detected, then the STA may switch to the next preferred WUR channel which is part of the agreed WUR channel set. If a STA failed to detect WUR beacon/synchronization signals on one or more WUR channels that are part of the agreed WUR channel set, then the STA may turn on its primary radio and renegotiate with the AP the WUR channel set, which may contain one or more subchannels or RUs.

In certain scenarios, the STA may request WUR channel sounding by the AP. For example, the STA may request the AP to perform WUR channel sounding if any of the advertised WUR channels (e.g., subchannels) of the WUR channel set are not suitable for the STA. As part of WUR channel sounding, the AP may transmit NDP frames and/or WUR sounding frames concurrently or consecutively over one or more or all available WUR channels. The STA may provide feedback based on the WUR sounding frames transmitted by the AP and received by the STA. The AP may adjust the advertised WUR channel set for the STA and/or the STA may renegotiate with the AP a new agreed upon WUR channel set (e.g., using the WUR request/response frame exchange sequence). In an example, a WUR request frame sent from a STA to the AP may include a sounding request for WUR channels.

Procedures for WUR transmissions may include the use of a WUR trigger frame. The following description of the WUR trigger frame may apply to a WUR response frame, or the WUR response frame described herein may be a WUR trigger frame. The AP may transmit a WUR trigger frame (or WUR response frame), which may carry information about WUR channel operation and assignment. The AP may transmit the WUR trigger frame over the main radio. In an example, the WUR trigger frame may be a unicast frame to one STA. In another example, the WUR trigger frame may be a broadcast or multicast frame to more than one STA. In the case of a multicast frame, the WUR trigger frame may have a trigger frame format and may include a trigger type field/value (e.g., in a common information field) that may be set to a "WUR trigger" type. An example of a WUR trigger frame format (which may also be a WUR response frame format) is shown in Table <NUM>.

Fields that may be included in a WUR trigger frame (or response frame) format include, but are not limited, to the following fields: a frame control field that may indicate the frame type is a WUR trigger frame; a duration field that may indicate the duration of the TXOP; a receiver address (RA) field; a transmitter address (TA) field; a common information (info) field; one or more user info fields; padding; and/or frame check sequence (FCS) field for cyclic redundancy check. The RA field may be the address of the STA receiving the WUR trigger frame and may be a group MAC address (e.g., for multiple STAs). The TA field may include the address of the AP/STA transmitting the WUR trigger frame. The common info field may include any one more or more of the following example subfields. For example, the common info field may include a WUR operating channels field and/or a WUR primary operating channels field. The common info field may include a WUR beacon/synchronization mode field, which may indicate whether the WUR beacon/synchronization signal will be transmitted over each WUR channel or the primary WUR channel. The common info field may include a WUR beacon interval or synchronization signal interval field, which may define the periodicity of the WUR synchronization signals. The common info field may include a WUR beacon offset, which may indicate whether a certain offset may be applied over the multiple WUR channels operated by the same AP (e.g., this may be used in scenarios where the WUR beacon/synchronization signal is transmitted over each WUR channel). The common info field may include a WUR channel switching allowed field, which may indicate whether a WUR channel switch is allowed. The common info field may include a WUR channel hopping allowed field, which may indicate whether WUR channel hopping may be allowed. In an example, the WUR channel switching allowed field and/or the WUR channel hopping allowed field may be included in the user Info field of the WUR trigger frame. The common info field may include a maximum monitoring duration, which may be the maximum duration that a STA may monitor a WUR channel before switching or hopping to a different WUR channel, or switching to the main radio.

The user info fields may each include any one more or more of the following example subfields. For example, a user info field may include the association identifier (AID) or WUR_ID identifying the STA in the WUR BSS. A user info field may include a WUR channel assignment field, a WUR channel hopping pattern field, and/or a WUR start time field. The WUR start time field may indicate the time that the STA may switch to the WUR (e.g., the start time may be set to x_duration before a WUR beacon/synchronization frame, where x_duration may be a small duration to allow the STA to switch from the main radio to the WUR).

In some scenarios, a full WUR negotiation procedure between the AP and the STA(s), as described above, may not be used or needed and instead a short WUR negotiation procedure (or short WUR negotiation signaling) may be used, as described in the following. For example, with WUR channel switching operations, the AP and STA may negotiate the use of and settings for WUR channel(s) before the STA enters WUR mode (i.e., while the STA is on the main radio/main channel). Once the STA is in WUR mode operating with the WUR and the main radio turned off (i.e., sleep mode), the STA may wake up its main radio and transmit on the main radio/main channel at intervals to request switching to other WUR channels. At these instances, the AP and STA may not renegotiate the use and/or settings of the WUR channel(s), but may only communicate regarding the next WUR channel for the WUR channel switch. Thus, the information exchanged between the AP and STA in this scenario may be "short" such that only a subset of parameters included in the initial WUR setup negotiation are exchanged, and a short WUR negotiation may be used. Similarly, channel hopping procedures and other WUR negotiation procedures may use the short WUR negotiation, as described below.

In an example, a trigger frame may be used to trigger multiple STAs (multi-STAs) to transmit short WUR signaling. In another example, the STA may transmit short WUR signaling and the AP may reply or respond with short WUR signaling with or without the AP sending a trigger frame. Then, the STA may go back to WUR mode using the updated WUR settings renegotiated using short WUR signaling.

<FIG> is a signaling diagram of an example short WUR negotiation procedure <NUM> using short WUR action frames. The AP <NUM> and STA <NUM> may negotiate and exchange WUR setup information during a WUR channel setup period <NUM>, for example via an exchange of WUR request frame <NUM>, WUR response frame <NUM>, and/or WUR signaling frame <NUM>. The WUR setup information may include, but is not limited to include, any of the following information: WUR beacon/synchronization information, WUR duty cycle information, WUR channel information, WUR data rate information, and/or short WUR negotiation information. The short WUR negotiation information may indicate that the STA <NUM> and/or the AP <NUM> may transmit short WUR action frame(s) over the main radio (PCR) during periods in the WUR procedure when the STA <NUM> temporarily switches on its PCR in order to receive updated WUR setup information.

Based on the WUR setup information, STA <NUM> may switch to a WUR channel <NUM> (or multiple WUR channels) during period <NUM> to monitor <NUM> for WUR beacon frames and/or wakeup packets transmitted from the AP <NUM> on the WUR channel <NUM>. The STA <NUM> may not receive a signal (e.g., wakeup STA frame <NUM>) from the AP during interval <NUM>. The STA <NUM> may follow a WUR duty cycle setup, and switch periodically between WUR duty on periods and WUR duty off periods to further save power. For example, when the STA <NUM> is in WUR duty off mode, the STA <NUM> may not monitor the WUR channel <NUM> and save more power (e.g., by turning off the WUR in addition to the main radio being off) or the STA may monitor the WUR channel <NUM> but only for WUR beacon/synchronization frames (and not other frames, such as wakeup STA frames). When the STA <NUM> is in WUR duty on mode, the STA may monitor for any frames over the WUR channel <NUM>.

The STA <NUM> may switch to the main radio to monitor main channel <NUM> during WUR operation, for example during time period <NUM>, in any of the following example scenarios. In an example scenario, the STA <NUM> may maintain a timer for the last received packet on a WUR channel <NUM> during period <NUM>. If the timer exceeds the maximum monitoring duration (e.g., as /pre-specified/negotiated), then the STA <NUM> may wakeup its main radio and switch to the main channel <NUM>. In another example scenario, the STA <NUM> may maintain a WUR beacon count or a count of missed WUR beacons. If the number or percentage of missed WUR beacons in a time period (e.g., period <NUM>) exceeds a parameter (e.g., MaxNumberMissedWURBeacons), then the STA <NUM> may turn on its main radio and monitor the main channel <NUM>. In another example scenario, if the number or percentage of received WUR beacons is below another parameter (e.g., MinNumberReceivedBeacons) in a time period (e.g., period <NUM>), then the STA <NUM> may turn on its main radio and monitor the main channel <NUM>.

In another example scenario, the STA <NUM> may switch to the main radio because the STA <NUM> detects a signal on the WUR channel <NUM> with an energy level below a threshold energy level that the STA <NUM> cannot decode. In another example scenario, the STA <NUM> may switch to the main radio because the STA <NUM> requests (e.g., suggests) to use a higher data rate on the currently assigned WUR channel <NUM>. The STA <NUM> may decide to request the higher rate because the STA <NUM> successfully decoded a /predetermined number of WUR packets when the STA <NUM> was operating below the maximum rate. In another example scenario, the STA <NUM> may switch to the main radio because the STA <NUM> requests (e.g., suggests) to use a lower rate on the currently assigned WUR channel <NUM>. The STA <NUM> may decide to request the higher rate because the STA <NUM> detects a transmission failure due to low SNR when the STA <NUM> was operating above the lowest rate. In another example scenario, the STA <NUM> may switch to the main radio because the STA <NUM> may wakeup periodically to report information to the AP <NUM>. Examples of information reported by the STA <NUM> to the AP <NUM> may include, but is not limited to include, WUR channel conditions and/or interference on a current or desired WUR channel (e.g., WUR channel <NUM>, WUR channel <NUM>). The AP <NUM> and STA <NUM> may negotiate the wakeup periodicity of the main radio during WUR operation during the initial WUR setup frame exchanges (e.g., exchange of WUR request frame <NUM>, WUR response frame <NUM>, and/or WUR signaling frame <NUM> during period <NUM>).

The STA <NUM> may transmit a short WUR action frame <NUM> on a main radio on main channel <NUM> when the STA <NUM> switches on its main radio in order to update WUR setup information. In an example, the transmission of a short WUR action frame <NUM> may be determined and/or negotiated in a previous WUR setup frame exchange on the main channel <NUM> (e.g., exchange of WUR request frame <NUM>, WUR response frame <NUM>, and/or WUR signaling frame <NUM> during period <NUM>). The short WUR frame <NUM> may include any of the following example information: a short WUR indication that indicates that the WUR frame <NUM> is a short WUR frame; the reason for current wakeup of the main radio of the STA <NUM> (e.g., MaxMonitoringDuration timeout, TooManyMissedWURBeacons exceeded, rate adaptation, channel switching, or channel hopping); and/or the short WUR request, which indicates that the STA requests a short WUR Action frame from the AP to change the WUR setting.

The WUR signaling frames <NUM>, <NUM>, and <NUM> transmitted between the two WUR switching or hopping intervals HI <NUM> and HI <NUM> may be simplified or short frames. For example, the WUR signaling frames <NUM>, <NUM>, and <NUM> may or may not be the same type of frame as transmitted during the initial WUR negotiation and setup phase (e.g., WUR request frame <NUM>). For example, the WUR signaling frame <NUM> may be a WUR request NDP frame, which may include a field (e.g., in the signal (SIG) or SIG-A/B field) to indicate an NDP medium access control (MAC) frame, and/or a field to indicate the type of NDP frame (e.g., a value may be set to indicate a WUR request NDP frame). For example, once the NDP MAC frame field is set, the SIG field and/or SIG-A/B fields may indicate the wakeup reason.

In another example, the WUR signaling frame <NUM> may be a WUR response NDP frame, which may include a field (e.g., in the SIG or SIG-A/B field) to indicate an NDP MAC frame, and/or a field to indicate the type of NDP frame (e.g., a value may be set to indicate the WUR response NDP frame). For example, once the NDP MAC frame field is set, the SIG field and/or SIG-A/B fields may including any of the following information: updated WUR channel assignment (e.g., the channel index or a bitmap of channels); updated WUR primary channel (e.g., the channel index or a bitmap of channels); updated WUR rate setting (e.g., the rate index); and/or updated duty cycle setting. In another example, instead of using an NDP MAC frame format for the short WUR action frame <NUM>, short WUR MAC frames may be designed using a QoS null frame or a MAC frame.

AP <NUM> may receive the short WUR frame <NUM> from the STA <NUM> and may determine to transmit a short WUR action frame <NUM> to the STA <NUM> in response, for example if a response was negotiated in previous WUR setting, and/or a reason for wakeup was indicated in the received short WUR frame <NUM>. In an example not shown, the AP <NUM> may respond to short WUR action frame <NUM> with a full WUR action frame (i.e., not short). The short WUR action frame <NUM> transmitted by the AP <NUM> may include any of the following information (fields): a short WUR indication field that may indicate the WUR action frame <NUM> is a short WUR action frame; a WUR setting update field that may indicate an updated WUR channel assignment; an updated WUR primary channel field; an updated WUR rate setting field; and/or an updated duty cycle setting field.

The STA <NUM> may receive the short WUR action frame <NUM> from the AP <NUM> and may respond to the AP <NUM> with a WUR signaling frame or a short WUR action frame <NUM> on the main channel <NUM> to indicate that the STA <NUM> will switch back to a WUR channel (e.g., WUR channel <NUM>) and/or to confirm the updated WUR setting based on the short WUR action frame exchange during period <NUM>. During WUR period <NUM>, the STA <NUM> may monitor <NUM> WUR channel <NUM> and receive a wakeup STA frame <NUM> from the AP <NUM>.

Procedures may be used to update a subset of existing WUR operating parameters in a WUR-enabled STA using a WUR transit mode. In a WUR transit mode, signals may be transmitted over main radio, and the negotiated WUR parameters may remain valid until they are modified or updated, for example by a short WUR frame or other control/management frames that may be used to update one or more of the of the WUR parameters. For example, a transit mode may be used to efficiently perform channel and/or rate adaption. <FIG> shows a state diagram of an example radio operation transition procedure 1000A for a WUR-enabled STA. In PCR mode <NUM> and transit mode <NUM> the STA has the PCR turned on and the WUR turned off, and in WUR mode <NUM> the STA has the PCR turned off (e.g., in sleep or doze state) and the WUR turned on. In PCR mode <NUM>, the STA may operate according to non-WUR <NUM> operation (e.g., according to <NUM>. 11AC or <NUM>. When the STA transitions between PCR mode <NUM> and WUR mode <NUM>, the STA may complete full WUR parameter negotiation <NUM> (from PCR <NUM> mode to WUR mode <NUM>) and/or full WUR teardown (from WUR mode <NUM> to PCR mode <NUM>). WUR teardown may include frame exchanges between the STA and AP over the PCR indicating that the STA is discontinuing the current WUR mode and current WUR parameters are no longer valid. When the STA transitions between WUR transit mode <NUM> and WUR mode <NUM>, the STA may use short WUR negotiation procedures <NUM>, as described herein (e.g., as described in <FIG>) such that the STA may maintain some, most or even all previously negotiated WUR parameters for the next time that the STA enters WUR mode <NUM>.

<FIG> is a flow diagram of an example WUR channel parameter renegotiation procedure 1000B that may be performed by a WUR-enabled STA between transitioning between WUR mode and transit mode. Short WUR frames may be used for the parameter renegotiation. At <NUM>, the STA may monitor for WUR beacons (and/or WUR frames) over an assigned WUR channel. At <NUM>, the STA may determine if the STA has successfully received any WUR beacons (or WUR frames) within a duration (e.g.. , a time period of MaxBeaconMonitoringDuration).

If the STA has not received WUR beacons (or WUR frames) within the duration, it may be because the WUR channel condition may not support reliable transmissions, then the STA may perform any of the following actions. At <NUM>, the STA may switch to PCR with WUR transit mode and may set a wakeup reason to "WUR channel quality may not support reliable transmission". At <NUM>, the STA may wakeup/switch to the main radio (PCR) and may send to the AP a short WUR request frame that includes the wakeup reason and/or the STA may send a control/management frame that includes the wakeup reason and WUR parameters (e.g., WUR channel assignment) to be updated. At <NUM>, the STA may receive over the main radio a Short WUR response frame or any other control/management frame, which may include a new WUR channel assignment (e.g., the channel assignment may be indicated by a WUR channel index, PCR channel index, or channel bitmap). At <NUM>, the STA may send a WUR signal indicating that the STA is switching to the WUR (and dozing the main radio) according to the new WUR channel assignment, and according to any updated WUR parameters. WUR parameters that were not updated may remain the same as previously negotiated.

If the STA has successfully received a WUR beacon within the duration, then at <NUM>, the STA may determine if the STA has received WUR frames within a duration (e.g., MaxWURFrameMonitoringDuration). If the STA receives some WUR beacon frames but does not receive any or enough WUR frames within the duration (as determined at <NUM>), then at <NUM>, the STA may determine whether or not the STA is operating at the lowest WUR data rate. If the STA is already operating at the lower WUR rate, then it may be because the WUR channel condition cannot support reliable transmission and the STA may proceed to per <NUM>-<NUM>, as described above.

If the STA is not operating at the lowest WUR rate, then at <NUM> the STA may switch to PCR with WUR transit mode and set the wakeup reason to "WUR data rate is too high". At <NUM>, the STA may switch to the main radio and send a short WUR request frame that includes the wakeup reason, and/or the STA may send a control/management frame that includes the wakeup reason and WUR parameters to be updated. At <NUM>, the STA may receive a short WUR response frame or any other control/management frame, which may include a new WUR rate assignment for the STA. At <NUM>, the STA may send a WUR signal indicating that the STA is switching to the WUR (and dozing the main radio) according to the new WUR rate assignment, and according to any updated WUR parameters. WUR parameters that were not updated may remain the same as previously negotiated.

If at <NUM> and <NUM> it is determined that the STA has successfully received a sufficient number WUR beacons and WUR frames (e.g., as compared to one or more thresholds) within a certain period of time, then at <NUM> the STA may follow instructions according to the received WUR frame(s) and may continue using the previously negotiated WUR parameters.

The examples above refer to example predetermined time durations MaxBeaconMonitoringDuration and MaxWURFrameMonitoringDuration. MaxBeaconMonitoringDuration may be a maximum duration that a STA monitors for beacon frames using the PCR. If no Beacon frames are detected during the MaxBeaconMonitoringDuration, the STA may switch to PCR mode or WUR transit mode. The MaxBeaconMonitoringDuration may be set according to a WUR beacon interval. For example, the MaxBeaconMonitoringDuration may be set to be M times a WUR beacon interval, where M or MaxBeaconMonitoringDuration may be a /predetermined/preconfigured integer number. In the case M or MaxBeaconMonitoringDuration is configurable, it may be signaled in a WUR action frame or other control/management frames that carry WUR parameters and are transmitted over PCR. The MaxBeaconMonitoringDuration may be determined by the STA category or STA type. For example, a table may be defined and each STA category may have its own default MaxBeaconMonitoringDuration. Thus, by STA capability exchange, the MaxBeaconMonitoringDuration may be explicitly or implicitly determined. For example, STA categories may be defined as follows (where X1, X2 and T may be preconfigured or predfined): on average, the STA may expect minimum traffic exchanges (<X1 Mbits) with an AP within T time duration; on average, the STA may expect medium traffic exchanges (>=X1 Mbits and <X2 Mbits) with an AP within T time duration; on average the STA may expect high traffic exchanges (>=X2 Mbits) with an AP within T time duration.

The MaxWURFrameMonitoringDuration may be a maximum duration that a STA may monitor for WUR frames. If no WUR frames are detected during the MaxWURFrameMonitoringDuration, the STA may switch to PCR mode or WUR transit mode. The MaxWURFrameMonitoringDuration may be a /predetermined/preconfigured number. In the case that MaxWURFrameMonitoringDuration is configurable, it may be signaled in a WUR action frame or other control/management frames that carry WUR parameters and are transmitted over PCR. The MaxWURFrameMonitoringDuration may be determined by the STA category or STA type. For example, a table may be defined and each STA category may have its own default MaxWURFrameMonitoringDuration. Thus, by STA capability exchange, the MaxWURFrameMonitoringDuration may be explicitly or implicitly determined.

In an example, one duration, "MaxMonitoringDuration" may be defined/configured that may be used as the maximum duration for WUR beacon monitoring and WUR frame monitoring. If a STA does not detect any WUR packets (beacon or WUR frames) over the MaxMonitoringDuration, then the STA may enter PCR mode or WUR transit mode. The MaxMonitoringDuration may be a /predetermined/preconfigured number. In the case that MaxMonitoringDuration is configurable, it may be signaled in a WUR action frame or other control/management frames that carry WUR parameters and are transmitted over PCR. The MaxMonitoringDuration may be determined by the STA category or STA type. For example, a table may be defined and each STA category may have its own default MaxMonitoringDuration. Thus, by STA capability exchange, the MaxMonitoringDuration may be explicitly or implicitly determined.

To simplify an <NUM>. 11ba WUR-enabled STA, <NUM>. 11ba WUR signals (e.g., transmitted by an AP) may be limited to a certain frequency band. However, the WUR signals may not be successfully demodulated at the WUR receiver in cases where the WUR receiver experiences fading due to the multipath channel. To guard against the multipath channel fading experienced on any one frequency band, a WUR receiver may monitor different frequency bands periodically. According to an example procedure for configuring the frequency bands/channels monitored by a WUR receiver in an <NUM>. 11ba WUR-enabled STA, the AP may send an indication or signaling to indicate the frequency band(s) to the main radio (PCR) of the WUR-enabled STA. The PCR of the WUR-enabled STA may configure its WUR receiver such that the WUR receiver may periodically monitor for the <NUM>. 11ba signals from the indicated frequency bands/channels. For example, an AP may transmit the WUR signals by using the negotiated frequency bands/channels periodically, and the WUR receiver may accordingly be periodically tuned to the indicated frequency bands receive the <NUM>. 11ba signals from the indicated frequency bands.

In another example, the main radio (e.g., the <NUM>. 11ax radio) of a WUR-enabled STA may indicate the frequency bands for <NUM>. 11ba signals to an AP. For example, the frequency bands may be part of the radio capability settings, and may be transmitted to an AP based on a request from the AP. In response, the AP may indicate the frequency bands that may include <NUM>. 11ba signals to the main radio of a WUR-enabled STA before the main radio enters a sleep mode. In another example, the AP may acknowledge the indicated frequency bands for <NUM>. 11ba signals by transmitting an acknowledge signal to the main radio of the WUR-enabled STA. Once the bands for <NUM>. 11ba signals are negotiated for both STA and AP, the STA may adjust the settings of the WUR receiver (e.g., <NUM>. 11ba receiver) to scan on the indicated bands. The AP may transmit the <NUM>. 11ba signals by using the negotiated frequency bands periodically. The WUR receiver in the STA may be tune periodically to receive the signals from the indicated frequency bands. In another example, the frequency bands that may include <NUM>. 11ba signals may be directly indicated to the WUR of the STA via <NUM>. 11ba signal through a WUR primary channel. In another example, a set of WUR channels may be defined as primary WUR frequency bands.

<FIG> is a frequency allocation diagram of an example frequency allocation <NUM> for a WUR-enabled STA <NUM>. The frequency allocation <NUM> may include an <NUM>. 11ax allocation of frequency bands <NUM> to be used by the main radio (PCR) of the STA <NUM>. The frequency allocation <NUM> may further include frequency locations/channels/bands <NUM> and <NUM> as the default frequency bands to be used by the WUR of STA <NUM> to monitor for WUR signals. The bands <NUM> and <NUM> may be indicated to STA <NUM>, for example by an AP (not shown). The WUR of STA <NUM> may scan the bands <NUM> and <NUM> and the STA <NUM> may skip on frequency bands, such as frequency band <NUM>, when performing WUR frequency scans. The WUR channels for the STA <NUM> may be changed such that the WUR may scan newly indicated bands (e.g., the WUR frequency bands may change to frequency bands <NUM> and <NUM>).

Although embodiments and examples described herein consider <NUM> specific protocols, it is understood that the solutions described herein are not restricted to these scenarios and are applicable to other wireless systems as well.

Claim 1:
A station, STA (<NUM>, <NUM>), the STA comprising:
a transceiver; and
a processor, wherein the transceiver and the processor are configured to:
send in a main radio operating mode, to an access point, AP (<NUM>), a wakeup radio, WUR (<NUM>), request frame including WUR duty cycle information, WUR channel information, and WUR data rate information;
receive in the main radio operating mode, from the AP (<NUM>), in response to the WUR request frame, a WUR response frame including an indication of a first WUR channel assignment and an indication of a WUR beacon interval; and
switch to a WUR operating mode and monitor a wireless medium for WUR signals, from the AP (<NUM>),
on a first WUR channel in accordance with the indicated first WUR channel assignment and the indicated WUR beacon interval.