Coexistence enhancements for wake-up radio

Abstract

Coexistence enhancements for wake-up radio are provided. In one configuration, a device is configured to transmit a wake-up radio (WUR) signal, determine whether to transmit a second signal within a SIFS after transmitting the WUR signal to improve medium reuse, and transmit the second signal within the SIFS after transmitting the WUR signal based on the determination. The second signal can be a data frame, a management frame, a control frame, an ACK frame, or a CF-end frame to enable legacy devices that cannot decode the WUR signal to avoid wasted airtime caused by an EIFS following the WUR signal. In another configuration, the device is configured to transmit a CTS-to-self frame, determine to transmit a second signal within a SIFS after transmitting the CTS-to-self frame, and transmit the second signal based on the determination. The second signal can be a WUR signal or an intermediate signal followed by a WUR signal.

Description

[0001] This application is a divisional application of the invention patent application entitled “Coexistence Enhancement for Wake-up Radio” with an international application date of February 27, 2018 and application number 201880013630.9 (international application number PCT / US2018 / 020002).

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of priority to U.S. Provisional Application No. 62 / 464,304, filed on February 27, 2017, entitled “COEXISTENCE ENHANCEMENTS FOR WAKE-UP RADIO,” and U.S. Patent Application No. 15 / 905,785, filed on February 26, 2018, entitled “COEXISTENCE ENHANCEMENTS FOR WAKE-UP RADIO,” both of which are expressly incorporated herein by reference in their entirety. Technical Field

[0004] The present disclosure relates generally to communication systems, and more particularly to coexistence enhancements for wake-up radio (WUR). Background Art

[0005] In many telecommunications systems, a communication network is used to exchange messages between several spatially separated interacting devices. Networks can be categorized based on their geographic scope, which can be, for example, a metropolitan area, a local area, or a personal area. Such networks are designated as wide area networks (WANs), metropolitan area networks (MANs), local area networks (LANs), wireless local area networks (WLANs), or personal area networks (PANs), respectively. Networks also differ based on the switching / routing technology used to interconnect the various network nodes and devices (e.g., circuit switching versus packet switching), the type of physical medium used for transmission (e.g., wired versus wireless), and the set of communication protocols used (e.g., Internet Protocol suite, Synchronous Optical Networking (SONET), Ethernet, etc.).

[0006] Wireless networks are often preferred when network elements are mobile and therefore have dynamic connectivity requirements, or when the network architecture is formed in an ad hoc rather than fixed topology. Wireless networks utilize an invisible physical medium using electromagnetic waves in radio, microwave, infrared, optical, and other frequency bands in an unguided propagation mode. Compared to fixed wired networks, wireless networks advantageously facilitate user mobility and rapid field deployment. Summary of the Invention

[0007] The systems, methods, computer-readable media, and devices of the present invention each have several aspects, no single aspect of which is solely responsible for the desirable attributes of the present invention. Without limiting the scope of the invention as expressed by the application documents, some features will now be briefly discussed. After considering this discussion, and particularly after reading the section entitled "Detailed Description," one will understand how the features of the present invention provide advantages for devices in wireless networks.

[0008] One aspect of the present disclosure provides an apparatus for wireless communication (e.g., an access point or another wireless device). The apparatus may be configured to transmit a first signal including a WUR signal. The apparatus may be configured to determine whether to transmit a second signal within a short interframe space (SIFS) after transmitting the WUR signal to improve medium reuse. The apparatus may be configured to transmit the second signal within the SIFS after transmitting the WUR signal based on the determination.

[0009] Another aspect of the present disclosure provides an apparatus for wireless communication (e.g., an access point or another wireless device). The apparatus may be configured to transmit a Clear to Send frame (CTS-to-self frame). The apparatus may be configured to determine whether to transmit a second signal within a SIFS after transmitting the CTS-to-self frame to improve medium reuse. The apparatus may be configured to transmit the second signal within the SIFS after transmitting the CTS-to-self frame based on the determination. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 An example wireless communication system is shown in which aspects of the present disclosure may be employed.

[0011] Figure 2 is a diagram of two approaches for protection / coexistence mechanisms according to the techniques described herein.

[0012] Figure 3 is a diagram of three approaches for protection / coexistence mechanisms using CTS-to-self frames according to the techniques described herein.

[0013] Figure 4 Shown in Figure 1 An example functional block diagram of a wireless device implementing WUR protection and coexistence within a wireless communication system.

[0014] Figure 5 is a flow chart of a first exemplary method of WUR protection and coexistence according to the techniques described herein.

[0015] Figure 6 is a flow chart of a second exemplary method of WUR protection and coexistence according to the techniques described herein.

[0016] Figure 7 is a functional block diagram of an example wireless communication device that can perform WUR protection and coexistence according to the techniques described herein. DETAILED DESCRIPTION

[0017] The various aspects of the novel system, device, computer-readable medium and method are described more fully below with reference to the accompanying drawings. However, the present disclosure can be implemented in many different forms and should not be interpreted as being limited to any specific structure or function given throughout the present disclosure. Specifically, these aspects are provided to make the present disclosure thorough and complete, and they will fully convey the scope of the present disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art will appreciate that the scope of the present disclosure is intended to cover any aspect of these novel systems, devices, computer-readable media and methods disclosed herein, regardless of whether they are implemented independently or in combination with any other aspect of the present invention. For example, any number of aspects set forth herein can be used to implement a device or practice method. In addition, the scope of the present invention is intended to cover such devices or methods practiced using other structures, functionality, or structure and functionality that are supplementary to or different from the various aspects of the present invention set forth herein. It should be understood that any aspect disclosed herein can be implemented by one or more elements of the claims.

[0018] Although specific aspects are described herein, numerous variations and permutations of these aspects fall within the scope of this disclosure. Although some benefits and advantages of preferred aspects are mentioned, the scope of this disclosure is not intended to be limited to specific benefits, uses, or objectives. Rather, various aspects of this disclosure are intended to be broadly applicable to different wireless technologies, system configurations, networks, and transmission protocols, some of which are illustrated by way of example in the accompanying drawings and the following description of preferred aspects. The detailed description and drawings merely illustrate the disclosure and do not limit it, the scope of which is defined by the appended claims and their equivalents.

[0019] Popular wireless network technologies may include various types of WLANs. WLANs may be used to interconnect nearby devices using widely used networking protocols. Various aspects described herein may be applied to any communication standard, such as a wireless protocol.

[0020] In some aspects, wireless signals may be transmitted according to the 802.11 protocol using orthogonal frequency division multiplexing (OFDM), direct sequence spread spectrum (DSSS) communication, a combination of OFDM and DSSS communication, or other schemes. Implementations of the 802.11 protocol may be used for sensors, metering, and smart grids. Advantageously, aspects of certain devices that implement the 802.11 protocol may consume less power than devices that implement other wireless protocols and / or may be used to transmit wireless signals over relatively long ranges (e.g., approximately 1 kilometer or more).

[0021] In some implementations, a WLAN includes various devices that serve as components for accessing the wireless network. For example, there can be two types of devices: access points (APs) and clients (also referred to as stations or "STAs"). Generally speaking, an AP can serve as the hub or base station of a WLAN, while a STA serves as a user of the WLAN. For example, a STA can be a laptop computer, a personal digital assistant (PDA), a mobile phone, etc. In one example, a STA connects to an AP via a wireless link compliant with Wi-Fi (e.g., the IEEE 802.11 protocol) to obtain general connectivity to the Internet or other wide area networks. In some implementations, a STA can also be used as an AP.

[0022] An access point may also include, be implemented as, or be referred to as a NodeB, a radio network controller (RNC), an evolved NodeB, a base station controller (BSC), a base transceiver station (BTS), a base station (BS), a transceiver function (TF), a radio router, a radio transceiver, an attachment point, or some other terminology.

[0023] A station may also include, be implemented as, or be referred to as an access terminal (AT), a subscriber station, a subscriber unit, a mobile station, a remote station, a remote terminal, a user terminal, a user agent, a user device, a user equipment, or other terminology. In some implementations, a station may include a cellular phone, a cordless phone, a Session Initiation Protocol (SIP) phone, a wireless local loop (WLL) station, a personal digital assistant (PDA), a handheld device with wireless connection capabilities, or other suitable processing equipment connected to a wireless modem. Accordingly, one or more aspects taught herein may be incorporated into a phone (e.g., a cellular phone or a smart phone), a computer (e.g., a laptop), a portable communication device, a headset, a portable computing device (e.g., a personal data assistant), an entertainment device (e.g., a music or video device, or a satellite radio), a gaming device or system, a global positioning system device, or any other suitable device configured to communicate via a wireless medium.

[0024] The terms "associated" or "association," or any variations thereof, should be given the broadest possible meaning within the context of this disclosure. For example, when a first device associates with a second device, it should be understood that the two devices may be associated directly or with an intermediary device. For simplicity, the process for establishing an association between two devices will be described using a handshake protocol that requires an "association request" from one of the devices followed by an "association response" from the other device. Those skilled in the art will appreciate that the handshake protocol may require additional signaling, such as, for example, signaling for providing authentication.

[0025] Any reference to an element such as "first", "second" or the like is used herein and does not generally limit the quantity or order of those elements. Specifically, these references are used herein as a convenient method for distinguishing two or more elements or element instances. Thus, the reference to the first element and the second element does not mean that only two elements can be adopted or that the first element must be located before the second element. In addition, the phrase "at least one" quoting a column of items refers to any combination of those items, including single members. As an example, "at least one of A, B, or C" is intended to encompass: A, or B, or C, or any combination thereof (e.g., AB, AC, BC, and ABC).

[0026] As discussed above, certain devices described herein may implement, for example, the 802.11 standard. Such devices (whether functioning as STAs, APs, or other devices) may be used for smart metering or in smart grids. Such devices may provide sensor applications or be used in home automation. These devices may alternatively or additionally be used in healthcare environments, such as for personal healthcare. These devices may also be used for monitoring to enable extended-range Internet connectivity (e.g., for use with hotspots) or to enable machine-to-machine communication.

[0027] Figure 1 An example wireless communication system 100 is shown in which aspects of the present disclosure may be employed. The wireless communication system 100 may operate in accordance with a wireless standard, such as the 802.11 standard. The wireless communication system 100 may include an AP 104 that communicates with STAs (e.g., STAs 112, 114, 116, and 118).

[0028] Various procedures and methods can be used for transmissions between the AP 104 and STAs in the wireless communication system 100. For example, signals can be sent and received between the AP 104 and the STAs using OFDM / OFDMA techniques. In this case, the wireless communication system 100 can be referred to as an OFDM / OFDMA system. Alternatively, signals can be sent and received between the AP 104 and the STAs using CDMA techniques. In this case, the wireless communication system 100 can be referred to as a CDMA system.

[0029] The communication link that facilitates transmissions from the AP 104 to one or more STAs may be referred to as a downlink (DL) 108, while the communication link that facilitates transmissions from one or more STAs to the AP 104 may be referred to as an uplink (UL) 110. Alternatively, the downlink 108 may be referred to as a forward link or forward channel, while the uplink 110 may be referred to as a reverse link or reverse channel. In some aspects, DL communications may include unicast or multicast traffic indications.

[0030] In some aspects, the AP 104 can suppress adjacent channel interference (ACI) so that the AP 104 can receive UL communications on more than one channel simultaneously without causing significant analog-to-digital conversion (ADC) clipping noise. The AP 104 can improve the suppression of ACI, for example, by having a separate finite impulse response (FIR) filter for each channel or having a longer ADC backoff period with an increased bit width.

[0031] The AP 104 can act as a base station and provide wireless communication coverage in a basic service area (BSA) 102. A BSA (e.g., BSA 102) is the coverage area of an AP (e.g., AP 104). The AP 104, together with the STAs associated with and using the AP 104 for communication, can be referred to as a basic service set (BSS). It should be noted that the wireless communication system 100 may not have a central AP (e.g., AP 104), but rather may function as a peer-to-peer network between STAs. Accordingly, the functions of the AP 104 described herein may alternatively be performed by one or more STAs.

[0032] AP 104 may transmit beacon signals (or simply "beacons") to other nodes (STAs) of the wireless communication system 100 via a communication link (such as downlink 108) on one or more channels (e.g., multiple narrowband channels, each including a frequency bandwidth). This may help other nodes (STAs) synchronize their timing with AP 104 or provide other information or functionality. Such beacons may be transmitted periodically. In one aspect, the period between successive transmissions may be referred to as a superframe. The transmission of beacons may be divided into several groups or intervals. In one aspect, beacons may include, but are not limited to, information such as: timestamp information for setting a common clock, a peer network identifier, a device identifier, capability information, a superframe duration, transmission direction information, reception direction information, a neighbor list, and / or an extended neighbor list, some of which are described in more detail below. Thus, a beacon may include both information that is common (e.g., shared) among several devices and information that is specific to a given device.

[0033] In some aspects, a STA (e.g., STA 114) may be required to associate with an AP 104 in order to send and / or receive communications to and from the AP 104. In one aspect, information for association is included in a beacon broadcast by the AP 104. To receive such a beacon, the STA 114 may, for example, perform a wide coverage search over the coverage area. For example, the search may also be performed by the STA 114 by sweeping the coverage area in a lighthouse manner. After receiving the information for association, the STA 114 may transmit a reference signal, such as an association probe or request, to the AP 104. In some aspects, the AP 104 may use a backhaul service to communicate, for example, with a larger network, such as the Internet or a public switched telephone network (PSTN).

[0034] In one aspect, the AP 104 may include one or more components for performing various functions. For example, the AP 104 may include a WUR component 124 that is configured to perform procedures related to WUR and enable coexistence between WUR and other wireless communications, including 802.11 legacy STAs that cannot recognize WUR transmissions. In one configuration, the WUR component 124 may be configured to transmit a first signal including a WUR signal. The WUR component 124 may be configured to determine that a second signal is to be transmitted within a SIFS after transmitting the WUR signal to improve medium reuse. The WUR component 124 may be configured to transmit the second signal within a SIFS after transmitting the WUR signal based on the determination. In another configuration, the WUR component 124 may be configured to transmit a CTS-to-self frame. The WUR component 124 may be configured to determine that a second signal is to be transmitted within a SIFS after transmitting the CTS-to-self frame to improve medium reuse. The WUR component 124 may be configured to transmit the second signal within a SIFS after transmitting the CTS-to-self frame based on the determination.

[0035] A WUR is a power-saving mechanism in wireless communications. A typical WLAN radio (e.g., a transceiver) in a wireless device (e.g., STA 114) can consume significant power, even when the wireless device is not transmitting or receiving data. For example, the wireless device may consume power to monitor traffic on the shared medium to determine whether there are incoming data packets or to determine whether the medium is idle for the wireless device to transmit. One way to reduce power consumption is to allow the wireless device to enter a sleep mode during which the primary WLAN radio can be turned off. While this technique reduces power consumption, it also increases communication latency. While in sleep mode, the wireless device can frequently and periodically monitor incoming packets, but monitoring may result in greater power consumption. On the other hand, if the wireless device does not monitor transmitted packets frequently, latency may increase. Alternatively, the WUR can be a dedicated radio separate from the primary radio (e.g., a secondary radio) or a subcomponent of the primary radio (e.g., sharing one or more components with the primary radio) that is used to activate the primary radio. In one aspect, the WUR can share a radio frequency (RF) front end with the primary radio. The WUR can have a relatively simple design and therefore may consume much less power than a conventional radio. For example, a typical radio might consume 20mA, while a WUR might consume less than 1mA. The function of the WUR is to receive a paging signal dedicated to the wireless device (e.g., a WUR signal), which indicates that data is available for the wireless device. When the WUR receives a paging signal for the wireless device, the WUR can instruct the wireless device to wake up the main radio to receive the data. In order to keep the design of the WUR simple, the paging signal can be modulated using a simpler modulation scheme, such as on-off keying (OOK), which refers to a simple form of amplitude shift keying (ASK). In one aspect, the WUR can be normally on or can be duty cycle controlled (e.g., 1ms intervals).

[0036] WUR or paging signals can be transmitted in the same frequency band as other WLAN signals. As such, there is a need to protect WUR signals from interference caused by other transmissions (e.g., transmissions from legacy devices that cannot recognize WUR signals). If the WUR signal is interfered with or collides with other transmissions, the targeted wireless device may not wake up, which will result in packet delays and increased latency.

[0037] Protection / coexistence mechanisms can be used to protect WUR signals from interference. The first approach is to use length information pre-appended to the preamble of the WUR signal to protect the WUR signal. The second approach is to use the network allocation vector (NAV) field of the clear send to self frame (CTS-to-self) to protect the WUR signal. However, as discussed further below, each mechanism includes some disadvantages, and therefore improvements to the mechanism are also proposed.

[0038] Figure 2 FIG200 is a diagram illustrating two approaches for protection / coexistence mechanisms. In the first approach 210, a first wireless device (such as AP 104) may transmit a wake-up signal 212 (e.g., a wake-up signal frame) to a second wireless device (such as STA 114) that includes a legacy preamble 214 (e.g., an IEEE 802.11a preamble) and a WUR signal 216. The legacy preamble 214 may include several fields, such as a legacy short training field (L-STF) for packet detection and automatic gain control (AGC) setup, a legacy long training field (L-LTF) for frequency offset, channel estimation, and timing information, and an L-SIG field that indicates a data transmission rate (e.g., a modulation and coding scheme (MCS), the number of bits to be transmitted, and / or the length or duration between the legacy signal (L-SIG) field in the wake-up signal 212 and the end of the wake-up signal 212). The second wireless device to which the WUR signal 216 is intended may wake up after receiving the WUR signal 216. In an aspect, the WUR signal 216 may include a paging identifier that identifies the second wireless device and indicates that data is available for the second wireless device. Figure 2 ) preamble and payload separated by the legacy preamble 214 shown in . The preamble may include one or more STF, LTF, and SIG fields. The payload may include a paging identifier that identifies the wireless device to be woken up. Other wireless devices to which the WUR signal 216 is not intended may not transmit within the remaining duration of the length or duration indicated in the L-SIG field of the wake-up signal 212 in the wake-up signal 212. Because other wireless devices may not transmit during the duration of the wake-up signal 212, this mechanism provides protection for the WUR signal 216 and enables coexistence of the WUR signal 216, which may be referred to as PHY layer protection.

[0039] However, in some instances, there may be legacy wireless devices that cannot decode the WUR signal 216. For example, there may be wireless devices (e.g., STAs) that are not WUR capable, such as wireless devices that do not have WUR. Wireless devices that do not have WUR capability can decode the legacy preamble 214 to know the end of the wake-up signal 212, but cannot decode the WUR signal 216. In some instances, there may be wireless devices with WUR capability that cannot decode the WUR signal 216 due to weak signal strength or other channel impairments. Wireless devices that do not have WUR capability that cannot decode the WUR signal 216 at the end time indicated by the legacy preamble 214 and wireless devices with WUR capability that cannot decode the WUR signal 216 at the end time indicated by the legacy preamble 214 may have to refrain from transmitting within at least the extended interframe space (EIFS), which results in wasted channel resources or airtime.

[0040] In order to reduce the possibility of wasting channel resources, a second method 250 is provided. Figure 2 , under the second approach 250, a first signal 252 is transmitted. Like the wake-up signal 212, the first signal 252 includes a legacy preamble 214 and a WUR signal 216. Similar to the first approach 210, the first wireless device may transmit the first signal 252. Subsequently, the first wireless device may append or transmit a second signal 260 that is decodable or a legal legacy 802.11 transmission after transmitting the WUR signal 216. That is, the first wireless device may transmit the second signal 260 within a SIFS 254 after transmitting the WUR signal 216. By transmitting the second signal 260 within a SIFS 254 delay after transmitting the WUR signal 216, the first wireless device may not need to contend for the medium again. In one aspect, the second signal 260 may be a legacy frame that can be decoded by a legacy device. For example, the second signal 260 may be an acknowledgment (ACK) frame (with its own destination), a contention-free end (CF-end) frame, a data frame, a management frame, a control frame, or any other legacy frame. When the legacy device receives the second signal 260, the legacy device will be able to decode the frame and, therefore, may not need to wait for EIFS before transmitting. Once the legacy frame is transmitted and successfully decoded by the legacy device, the EIFS rule will be overridden, and the legacy device may transmit after decoding the legacy frame. In one aspect, data frames, management frames, control frames, or other valid data frames transmitted after the WUR signal 216 may be received by devices with WUR capabilities as well as legacy devices.

[0041] In one aspect, ACK frames and CF-end frames may have a duration shorter than EIFS. In this way, ACK frames and CF-end frames may be preferred at legacy devices with respect to reducing delays after the end of the WUR signal 216 because ACK frames and CF-end frames do not contain data, and legacy devices may wait for a duration shorter than EIFS before transmitting. For example, a legacy STA may receive an ACK frame to terminate the EIFS delay. In one aspect, a legacy STA may receive a CF-end frame as an indication of the end of a contention-free period so that the legacy STA can contend for channel resources without waiting for the end of EIFS. ACK and CF-end frames may be referred to as non-valid data frames and may include other types of frames that do not contain valid data. In contrast, data frames, management frames, control frames, and other frames that contain valid data may be shorter or longer than EIFS. However, even when such frames are longer than EIFS, no medium or airtime is wasted because the first wireless device is transmitting information. In one aspect, the first wireless device may determine whether there are any legacy STAs nearby, such as STAs that do not have WUR capabilities. If there is a legacy STA nearby, the first wireless device may determine whether there are any data frames, management frames, control frames, or other valid data frames waiting to be transmitted. If there are data frames, management frames, control frames, or other valid data frames to be transmitted, the first wireless device may transmit the data frames, management frames, control frames, or other valid data frames within SIFS254 after the end of the WUR signal 216 to avoid wasted air time caused by EIFS. Otherwise, the first wireless device may transmit an ACK frame or a CF-end frame within SIFS254 after the end of the WUR signal 216 to terminate the EIFS early. On the other hand, the first wireless device may transmit one or more non-valid data frames (e.g., ACK frames or CF-end frames) within SIFS254 without first determining whether or whether there are any data frames, management frames, or other valid data frames available for transmission due to the shorter duration of the non-valid data frames or due to regulatory constraints.

[0042] Figure 33 is a diagram of three approaches to a protection / coexistence mechanism using a CTS-to-self frame. Referring to the first approach 310, a first wireless device (e.g., AP 104) may send a CTS-to-self frame 314 and send a WUR signal 316 after a SIFS 318 delay after transmitting the CTS-to-self frame 314. The CTS-to-self frame 314 may include a duration (e.g., a NAV field) indicating when the WUR signal 316 ends. Wireless devices receiving the CTS-to-self frame 314 may update their respective NAVs and may determine not to transmit for at least the duration including the WUR signal 316. In this way, protection and coexistence for the WUR signal 316 are provided based on the duration indicated in the CTS-to-self frame 314. Such protection may be referred to as MAC layer protection. However, in some instances, the CTS-to-self frame 314 may be transmitted using a bandwidth and / or transmit power that is different from the bandwidth and / or transmit power of the WUR signal 316. For example, the CTS-to-self frame 314 may have a wider bandwidth and greater transmit power than the WUR signal 316. Due to differences in transmission characteristics, if the CTS-to-self frame 314 and the WUR signal 316 are sent on a dynamic frequency selection (DFS) channel (e.g., a channel that may include radar signals), some devices may mistakenly detect the WUR signal 316 as a radar signal. For example, due to changes in signal bandwidth and / or transmit power when receiving the CTS-to-self frame 314 followed by the WUR signal 316, a STA (e.g., a WUR-capable STA or a non-WUR-capable STA) may mistakenly detect the presence of a radar signal during the SIFS 318 between the CTS-to-self frame 314 and the WUR signal 316. When such devices detect a radar signal on a channel, they may be required to refrain from attempting to transmit on the channel for a predetermined period of time (e.g., 30 minutes). In this way, false positives regarding radar detection may significantly increase latency and unnecessarily reduce channel availability. In order to reduce the occurrence of false positives, two alternative approaches are proposed.

[0043] In the second approach 320, instead of waiting for the SIFS 318 delay to transmit the WUR signal 316, the first wireless device may transmit the CTS-to-self frame 314 and then transmit the WUR signal 316 within the SIFS 318 delay. By reducing the gap between the CTS-to-self frame 314 and the WUR signal 316, the occurrence of false positives may be reduced or avoided because the receiving device is less likely to interpret the WUR signal 316 as a separate radar signal.

[0044] In a third approach 330, the first wireless device may transmit an intermediate signal 340 after transmitting the CTS-to-self frame 314 but before transmitting the WUR signal 316. The intermediate signal 340 may be transmitted within a SIFS delay 318 of the end of transmission of the CTS-to-self frame 314. In one aspect, the intermediate signal 340 may be pure energy or may be specially encoded so that the intermediate signal 340 can improve the acquisition of the WUR signal 316. For example, the intermediate signal 340 may be designed based on the preamble format of the WUR signal 316 so that the intermediate signal 340 can help the wireless device receiving the WUR signal 316 with AGC calibration or sensitivity control to acquire the WUR signal 316. In one aspect, the intermediate signal 340 may be modulated using a simple modulation scheme (such as OOK) used to modulate the WUR signal 316. In one aspect, the intermediate signal 340 may include information about the payload of the WUR signal 316. After transmitting the intermediate signal 340, the first wireless device may transmit the WUR signal 316 after the SIFS 318 delay. By transmitting the intermediate signal 340 between the CTS-to-self frame 314 and the WUR signal 316, false positives regarding radar detection may be avoided or reduced.

[0045] Figure 4 Shown in Figure 1 1. An example functional block diagram of a wireless device 402 implementing WUR protection and coexistence within the wireless communication system 100 of FIG. 1. The wireless device 402 is an example of a device that can be configured to implement the various methods described herein. For example, the wireless device 402 can include an AP (e.g., AP 104).

[0046] The wireless device 402 may include a processor 404 that controls the operation of the wireless device 402. The processor 404 may also be referred to as a central processing unit (CPU). Memory 406 (which may include both read-only memory (ROM) and random access memory (RAM)) may provide instructions and data to the processor 404. A portion of the memory 406 may also include non-volatile random access memory (NVRAM). The processor 404 typically performs logical and arithmetic operations based on program instructions stored in the memory 406. The instructions in the memory 406 may be executable (e.g., executable by the processor 404) to implement the methods described herein.

[0047] Processor 404 may include or be a component of a processing system implemented with one or more processors. The one or more processors may be implemented with any combination of general-purpose microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), controllers, state machines, gated logic, discrete hardware components, dedicated hardware finite state machines, or any other suitable entity capable of performing calculations or other manipulations on information.

[0048] The processing system may also include a machine-readable medium for storing software. Software should be broadly interpreted to mean any type of instructions, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Instructions may include code (e.g., in source code format, binary code format, executable code format, or any other suitable code format). These instructions, when executed by the one or more processors, cause the processing system to perform the various functions described herein.

[0049] The wireless device 402 may also include a housing 408, and the wireless device 402 may include a transmitter 410 and / or a receiver 412 to allow transmission and reception of data between the wireless device 402 and a remote device. The transmitter 410 and the receiver 412 may be combined into a transceiver 414. An antenna 416 may be attached to the housing 408 and electrically coupled to the transceiver 414. The wireless device 402 may also include multiple transmitters, multiple receivers, multiple transceivers, and / or multiple antennas.

[0050] The wireless device 402 may also include a signal detector 418 that may be used to detect and quantify the level of a signal received by the transceiver 414 or the receiver 412. The signal detector 418 may detect signals such as total energy, energy per symbol per subcarrier, power spectral density, and other signals. The wireless device 402 may also include a DSP 420 for processing signals. The DSP 420 may be configured to generate packets for transmission. In some aspects, the packets may include physical layer convergence procedure (PLCP) protocol data units (PPDUs).

[0051] In some aspects, the wireless device 402 may further include a user interface 422. The user interface 422 may include a keypad, a microphone, a speaker, and / or a display. The user interface 422 may include any element or component that conveys information to a user of the wireless device 402 and / or receives input from the user.

[0052] When the wireless device 402 is implemented as an AP (e.g., AP 104), the wireless device 402 may also include a WUR component 424. The WUR component 424 may be configured to perform one or more functions described herein. For example, the WUR component 424 may be configured to append or transmit a signal that is decodable or is a valid legacy 802.11 transmission within SIFS after transmitting the WUR signal (e.g., Figure 2 The second signal 260 of the WUR signal can be used to improve medium reuse. In one aspect, the signal can be a legacy frame that can be decoded by a legacy device, such as an ACK frame (with a destination of its own), a CF-end frame, a data frame, a management frame, a control frame, or any other legacy frame. The WUR component 424 can be configured to determine whether there are any legacy STAs nearby, for example, STAs that do not have WUR capabilities. If there are legacy STAs nearby, the WUR component 424 can be configured to determine whether there are any data frames, management frames, control frames, or other valid data frames waiting to be transmitted. If so, the WUR component 424 can be configured to append data frames, management frames, control frames, or other valid data frames for transmission by the transmitter 410 and the antenna 416 within SIFS after the WUR signal ends. Otherwise, the WUR component 424 can be configured to append ACK frames, CF-end frames, or other non-valid data frames for transmission by the transmitter 410 and the antenna 416 within SIFS after the WUR signal ends. In one aspect, data frames, management frames, control frames, or other valid data frames appended after the WUR signal may be received by a WUR-capable STA.

[0053] In one aspect, the WUR component 424 may be configured to cause the wireless device 402 to transmit a CTS-to-self frame and a WUR signal within a SIFS delay to reduce the gap between the CTS-to-self frame and the WUR signal. In one aspect, the WUR component 424 may be configured to append an intermediate signal within a SIFS delay between the CTS-to-self frame and the WUR signal. In one aspect, the intermediate signal may be pure energy or may be specially encoded so that the intermediate signal may improve the capture of the WUR signal. The WUR component 424 may be configured to generate an intermediate signal based on the preamble format of the WUR signal so that the intermediate signal may assist in AGC calibration or sensitivity control for the purpose of capturing the WUR signal by a WUR-capable STA.

[0054] The various components of the wireless device 402 can be coupled together by a bus system 426. The bus system 426 can include, for example, a data bus, as well as a power bus, a control signal bus, and a status signal bus in addition to the data bus. The various components of the wireless device 402 can use some other mechanism to couple together or receive or provide input to each other.

[0055] although Figure 4 4, but one or more of these components may be combined or implemented together. For example, the processor 404 may be used to implement not only the functionality described above with respect to the processor 404, but also the functionality described above with respect to the signal detector 418, the DSP 420, the user interface 422, and / or the WUR component 424. In addition, Figure 4 Each component illustrated in the figures may be implemented using multiple separate elements.

[0056] Figure 5 4 is a flow chart of a first exemplary method 500 for WUR protection and coexistence. The method 500 may be performed using an apparatus (e.g., AP 104, or, for example, wireless device 402). Although the method 500 is described below with respect to Figure 4 Although the present invention is described with reference to elements of the wireless device 402, other components may be used to implement one or more steps described herein. Figure 5 Dotted lines in the may indicate optional operations.

[0057] At block 505, the apparatus may transmit a first signal comprising a WUR signal. The WUR signal may include a preamble and a payload. The preamble may include one or more STF, LTF, and SIG fields. The payload may include a paging identifier that identifies the wireless device to be awakened.

[0058] In box 510, the device may determine whether to transmit a second signal within SIFS after transmitting the WUR signal to improve medium reuse. If the device determines not to transmit the second signal within SIFS after transmitting the WUR signal, the device does not transmit the second signal at box 511. Otherwise, in one configuration, the device may determine to transmit the second signal by determining that the WUR signal has been transmitted (at 512) and by determining whether the device has additional data or control information for transmission (at 514). The additional data or control data may be a legacy frame that can be decoded by a legacy device, such as a data frame, a management frame, a control frame, or other valid data frame. The device may determine whether there are any legacy STAs nearby. In box 517, if there is a legacy STA nearby and if there is additional data or control information for transmission, the device may determine to transmit a data frame, a management frame, a control frame, or a valid data frame as the second signal. In block 516, if a legacy STA is nearby and if the device does not have additional data or control information to transmit, the device may determine to transmit an ACK frame (with its own destination), a CF-end frame, or other legacy non-valid data frame that can be decoded by legacy devices as the second signal.

[0059] At block 518, the apparatus may, based on the determination, transmit a second signal within the SIFS after transmitting the WUR signal. Legacy devices that receive data frames, management frames, or control frames as the second signal may use the data to utilize the over-the-air time that would otherwise be wasted during the EIFS following the WUR signal. Legacy devices that receive ACK frames (with their own destinations), CF-end frames, or other legacy non-data frames may use the frames to terminate the EIFS early to eliminate wasted over-the-air time, thereby improving medium reuse.

[0060] Figure 6 6 is a flow chart of a second exemplary method 600 for WUR protection and coexistence. The method 600 may be performed using an apparatus (e.g., AP 104, or, for example, wireless device 402). Although the method 600 is described below with respect to Figure 4 Although the present invention is described with reference to elements of the wireless device 402, other components may be used to implement one or more steps described herein. Figure 6 Dotted lines in the may indicate optional operations.

[0061] The device may transmit a CTS-to-self frame at block 605. The CTS-to-self frame may include a duration (eg, a NAV field) indicating when the WUR signal ends.

[0062] In box 610, the device may determine whether to transmit a second signal within SIFS after transmitting the CTS-to-self frame to improve medium reuse. If the device determines not to transmit the second signal within SIFS after transmitting the CTS-to-self frame, the device may not transmit the second signal at 511. Otherwise, in one configuration, the device may determine to transmit the second signal by determining that the CTS-to-self frame has been transmitted (at 612) and by determining whether a WUR signal will be transmitted to wake up another wireless device (at 614). In 611, if the WUR signal will not be transmitted, the device may not transmit the second signal. Otherwise, if the WUR signal will be transmitted, the device may transmit the second signal in box 615.

[0063] At block 615, the device may, based on the determination, transmit the WUR signal as a second signal within the SIFS after transmitting the CTS-to-self frame, rather than waiting for the SIFS delay to expire before transmitting the WUR signal. By reducing the gap between the CTS-to-self frame and the WUR signal, the occurrence of false positives may be reduced or avoided because the receiving device may not perceive the WUR signal as a separate radar signal.

[0064] In box 620, the device may transmit an intermediate signal as a second signal after transmitting the CTS-to-self frame but before transmitting the WUR signal. The intermediate signal may be transmitted within a SIFS delay of the end of the transmission of the CTS-to-self frame. In one aspect, the intermediate signal may be pure energy or may be specially encoded so that the intermediate signal can improve the capture of the WUR signal. For example, the intermediate signal may be designed based on the preamble format of the WUR signal so that the intermediate signal can help AGC calibration or sensitivity control for the purpose of capturing the WUR signal by a STA with WUR capability. The device may transmit the WUR signal at the end of the SIFS delay after transmitting the intermediate signal.

[0065] Figure 7 7 is a functional block diagram of an example wireless communication device 700 that can perform WUR protection and coexistence. The wireless communication device 700 may include a receiver 705, a processing system 710, and a transmitter 715. The processing system 710 may include a WUR component 724. The processing system 710, the WUR component 724, and / or the transmitter 715 may be configured to perform one or more functions disclosed herein. For example, the WUR component 724 may be configured to append or transmit a signal that is decodable or is a valid legacy 802.11 transmission within a SIFS after transmitting the WUR signal (e.g., Figure 2 The second signal 260 of the WUR signal can be used to improve medium reuse. In one aspect, the signal can be a legacy frame that can be decoded by a legacy device, such as an ACK frame (with a destination of its own), a CF-end frame, a data frame, a management frame, a control frame, or any other legacy frame. The WUR component 724 can be configured to determine whether there are any legacy STAs nearby, for example, STAs that do not have WUR capabilities. If there are legacy STAs nearby, the WUR component 724 can be configured to determine whether there are any data frames, management frames, control frames, or other valid data frames waiting to be transmitted. If so, the WUR component 724 can be configured to append data frames, management frames, control frames, or other valid data frames for transmission by the transmitter 715 within SIFS after the WUR signal ends. Otherwise, the WUR component 724 can be configured to append ACK frames, CF-end frames, or other non-valid data frames for transmission by the transmitter 715 within SIFS after the WUR signal ends. In one aspect, data frames, management frames, control frames, or other valid data frames appended after the WUR signal may be received by a WUR-capable STA.

[0066] In one configuration, the WUR component 724 may be configured to transmit the CTS-to-self frame and the WUR signal within a SIFS delay to reduce the gap between the CTS-to-self frame and the WUR signal. In another configuration, the WUR component 724 may be configured to append an intermediate signal within a SIFS delay between the CTS-to-self frame and the WUR signal. In one aspect, the intermediate signal may be pure energy or may be specially encoded so that the intermediate signal can improve the capture of the WUR signal. The WUR component 724 may be configured to generate the intermediate signal based on the preamble format of the WUR signal so that the intermediate signal can assist in AGC calibration or sensitivity control for the purpose of capturing the WUR signal by a WUR-capable STA.

[0067] The receiver 705, processing system 710, WUR component 724, and / or transmitter 715 may be configured to perform the above-described Figure 5 Boxes 505, 510 and 515 and Figure 6 Receiver 705 may correspond to receiver 412. Processing system 710 may correspond to processor 404. Transmitter 715 may correspond to transmitter 410. WUR component 724 may correspond to WUR component 124 and / or WUR component 424.

[0068] In one configuration, the wireless communication device 700 may include means for performing the functions described herein. For example, the wireless communication device 700 may include means for determining whether there are any legacy SRAs nearby, such as STAs that do not have WUR capabilities. If there are legacy STAs nearby, the wireless communication device 700 may include means for determining whether there are any data frames, management frames, control frames, or other valid data frames waiting to be transmitted. If so, the wireless communication device 700 may include means for appending data frames, management frames, control frames, or other valid data frames for transmission by the transmitter 715 within a SIFS after the WUR signal ends to improve medium reuse. Otherwise, the wireless communication device 700 may include means for appending ACK frames, CF-end frames, or other non-valid data frames for transmission by the transmitter 715 within a SIFS after the WUR signal ends.

[0069] In one configuration, the wireless communication device 700 may include a device for transmitting a CTS-to-self frame and a WUR signal within a SIFS delay to reduce the gap between the CTS-to-self frame and the WUR signal. In another configuration, the wireless communication device 700 may include a device for appending an intermediate signal within a SIFS delay between the CTS-to-self frame and the WUR signal. In one aspect, the intermediate signal may be pure energy or may be specially encoded so that the intermediate signal can improve the capture of the WUR signal. The wireless communication device 700 may include a device for generating an intermediate signal based on the preamble format of the WUR signal so that the intermediate signal can assist in AGC calibration or sensitivity control for the purpose of capturing the WUR signal by a STA with WUR capability.

[0070] In one configuration, a device for determining the availability of appending any data frame, management frame, control frame, or other valid data frame within SIFS after the end of a WUR signal and for appending any data frame, management frame, control frame, or other valid data frame within SIFS after the end of a WUR signal, a device for appending an ACK, CF-end frame, or other non-valid data frame within SIFS after the end of a WUR signal, a device for transmitting a CTS-to-self frame and a WUR signal within a SIFS delay to reduce a gap between the CTS-to-self frame and the WUR signal, and a device for appending an intermediate signal within a SIFS delay between the CTS-to-self frame and the WUR signal may include a processing system 710, a WUR component 724, and / or a transmitter 715.

[0071] The various operations of the above methods may be performed by any suitable means capable of performing these operations, such as various hardware and / or software components, circuits, and / or modules. Generally speaking, any operation illustrated in the drawings may be performed by corresponding functional means capable of performing these operations.

[0072] The various illustrative logical blocks, components, and circuits described in connection with the present disclosure may be implemented or performed using a general purpose processor, a DSP, an application specific integrated circuit (ASIC), an FPGA or other PLD, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

[0073] In one or more aspects, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted via a computer-readable medium as one or more instructions or code. Computer-readable media includes both computer storage media and communication media, including any medium that facilitates the transfer of a computer program from one location to another. A storage medium may be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media may include RAM, ROM, EEPROM, compact disc (CD) ROM (CD-ROM) or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Any connection is also properly referred to as a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. As used herein, disk and disc include CDs, laser discs, optical discs, digital versatile discs (DVDs), floppy disks, and Blu-ray discs, where disks typically reproduce data magnetically, while discs reproduce data optically with lasers. Thus, computer-readable media includes non-transitory computer-readable media (e.g., tangible media).

[0074] The methods disclosed herein include one or more steps or actions for implementing the described methods. These method steps and / or actions may be interchangeable with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and / or use of the specific steps and / or actions may be modified without departing from the scope of the claims.

[0075] Thus, some aspects may include a computer program product for performing the operations presented herein. For example, such a computer program product may include a computer-readable medium having stored (and / or encoded) thereon instructions, the instructions being executable by one or more processors to perform the operations described herein. For some aspects, the computer program product may include packaging materials.

[0076] In addition, it should be appreciated that the components and / or other appropriate means for performing the methods and techniques described herein can be downloaded and / or otherwise obtained by the user terminal and / or base station where applicable. For example, such a device can be coupled to a server to facilitate the transfer of the means for performing the methods described herein. Alternatively, the various methods described herein can be provided via a storage device (e.g., RAM, ROM, a physical storage medium such as a CD or floppy disk, etc.) so that once the storage device is coupled to or provided to the user terminal and / or base station, the device can obtain the various methods. In addition, any other suitable technology suitable for providing the methods and techniques described herein to a device may be utilized.

[0077] It will be understood that the claims are not limited to the precise configuration and components illustrated above. Various changes, substitutions and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

[0078] While the foregoing is directed to various aspects of the present disclosure, other and further aspects of the disclosure may be devised without departing from the basic scope thereof, the scope of which is determined by the claims that follow.

[0079] The foregoing description is provided to enable anyone skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the universal principles defined herein may be applied to other aspects. Accordingly, the claims are not intended to be limited to the aspects shown herein, but rather should be granted the full scope consistent with the language of the claims, wherein singular references to elements, unless otherwise specified, are not intended to mean "one and only one," but rather "one or more." Unless otherwise specified, the term "some" refers to one or more. All structural and functional equivalents of the various aspects described herein to those skilled in the art, whether currently or hereafter known, are expressly incorporated herein by reference and are intended to be covered by the claims. Furthermore, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly recited in the claims. No element of a claim should be construed under 35 U.S.C. §112(f) unless the element is explicitly recited using the phrase "means for..." or, in the case of a method claim, the element is recited using the phrase "step for..."

Claims

1. A wireless communication method of a first device associated with a wake-up radio (WUR), comprising: Transmits a Clear to Send (CTS-to-self) frame; determining whether to transmit a second signal within a short interframe space (SIFS) after transmitting the CTS-to-self frame to reduce false detection of radar signals by a second device receiving the CTS-to-self frame and the second signal; as well as The second signal is transmitted within the SIFS after transmitting the CTS-to-self frame based on the determination. 2 . The method of claim 1 , wherein the second signal is a wake-up-on-radio (WUR) signal.

3. The method of claim 1, wherein the second signal is transmitted at a transmission power different from a transmission power of the CTS-to-self frame.

4. The method of claim 1 , wherein the second signal is an intermediate signal, and wherein the method further comprises: The WUR signal is transmitted after the SIFS after the intermediate signal is transmitted. The method of claim 4 , wherein the intermediate signal helps the second device capture the WUR signal. The method of claim 4 , wherein the intermediate signal is modulated using a modulation scheme used for the WUR signal.

7. An apparatus for wireless communication associated with a wake-up radio (WUR), comprising: Memory; as well as at least one processor coupled to the memory, wherein the at least one processor is configured to: Transmits a Clear to Send (CTS-to-self) frame; determining whether to transmit a second signal within a short interframe space (SIFS) after transmitting the CTS-to-self frame to reduce false detection of radar signals by a second device receiving the CTS-to-self frame and the second signal; as well as The second signal is transmitted within the SIFS after transmitting the CTS-to-self frame based on the determination. The apparatus of claim 7 , wherein the second signal is a wake-up-on-radio (WUR) signal.

9. The apparatus of claim 7, wherein the second signal is transmitted at a transmission power different from a transmission power of the CTS-to-self frame.

10. The apparatus of claim 7, wherein the second signal is an intermediate signal, and wherein the at least one processor is further configured to: The WUR signal is transmitted after the SIFS after the intermediate signal is transmitted. The apparatus of claim 10 , wherein the intermediate signal helps a second device capture the WUR signal.

12. The apparatus of claim 10, wherein the intermediate signal is modulated using a modulation scheme used for the WUR signal.

13. An apparatus for wireless communication associated with a wake-up radio (WUR), comprising: means for transmitting a clear-to-send (CTS-to-self) frame; means for determining whether to transmit a second signal within a short interframe space (SIFS) after transmitting the CTS-to-self frame to reduce false detection of radar signals by a second device receiving the CTS-to-self frame and the second signal; as well as means for transmitting the second signal within the SIFS after transmitting the CTS-to-self frame based on the determination.

14. The apparatus of claim 13, wherein the second signal is a wake-up-on-radio (WUR) signal.

15. The apparatus of claim 13, wherein the second signal is transmitted at a transmission power different from a transmission power of the CTS-to-self frame.

16. The apparatus of claim 13, wherein the second signal is an intermediate signal, and wherein the apparatus further comprises: Means for transmitting a WUR signal after the SIFS after transmitting the intermediate signal.

17. The device of claim 16, wherein the intermediate signal helps a second device capture the WUR signal.

18. The apparatus of claim 16, wherein the intermediate signal is modulated using a modulation scheme used for the WUR signal.

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