CN108989254B

CN108989254B - Wireless communication method and wireless communication device

Info

Publication number: CN108989254B
Application number: CN201810550484.5A
Authority: CN
Inventors: 刘剑函; 皮尔二世汤姆士艾德华; 房敬良
Original assignee: MediaTek Inc
Current assignee: MediaTek Inc
Priority date: 2017-05-31
Filing date: 2018-05-31
Publication date: 2020-12-25
Anticipated expiration: 2038-05-31
Also published as: TW201904325A; TWI663886B; CN108989254A

Abstract

The present invention provides a wireless communication method and a wireless communication apparatus, the wireless communication method including: generating a packet comprising a first set of wake-up signals, wherein the generating the packet comprising the first set of wake-up signals comprises: allocating a subchannel of a first frequency channel for each of the first set of wake-up signals; modulating the first set of wake-up signals using on/off keying (OOK) modulation, wherein each of the first set of wake-up signals is to activate a primary radio located in a respective wireless communication device of the first set of wireless communication devices; transmitting the packet using frequency division multiplexing, FDMA, wherein each of the first set of wake-up signals is transmitted over a respective sub-channel of the first frequency channel. Using this method, wake-up signals for multiple wireless communication devices may be transmitted.

Description

Wireless communication method and wireless communication device

Technical Field

The present invention relates generally to the field of network communication technologies, and more particularly to the field of communication protocols for wireless communications.

Background

Wireless Local Area Networks (WLANs) and mobile communication devices, such as smart phones, wearable devices, various sensors, Internet of things (IoT) devices, and the like, are becoming increasingly popular. Portability requirements limit the overall size of communication devices, which are typically powered by built-in batteries of limited charging capacity. Most of the workload of a communication device can be driven by communications, which is a major source of power consumption since the radio needs to remain operational to ensure timely response to data communication requests.

To reduce power loss due to the radios, some communication devices include a master Radio and a low-power Wake-Up Radio (WUR). When not involved in data communication tasks, the primary radio can be configured in a power saving state, e.g., a sleep state or even turned off. On the other hand, the low power wake up wireless transceiver WUR remains active and operates to activate the host wireless transceiver whenever the WUR receives a data communication request directed to the host wireless transceiver, which may be in the form of a wake up signal sent by a WI-FI Access Point (AP), for example.

The WUR has low cost and low power consumption compared to a host wireless transceiver device with high rate data communication capabilities and complex processing functions, but still sufficient to receive and process the wake-up signal and wake-up the host wireless transceiver device accordingly. For example, the rated power consumption of the WUR can be 0.5-1mW or even less.

The IEEE802.11 standard organization defines a technical standard for WLANs. The latest IEEE802.11 standard employs Multi-User (MU) communication mechanisms, such as MU-MIMO and Orthogonal Frequency Division Multiple Access (OFDMA). However, there is a lack of a multi-user MU transmission mechanism that enables communication of synchronized wake-up signals between a transmitter and multiple WUR receivers.

Disclosure of Invention

An embodiment of the present invention provides a wireless communication method, including: generating a packet comprising a first set of wake-up signals, wherein the generating a packet comprising a first set of wake-up signals comprises: allocating a subchannel of a first frequency channel for each of the first set of wake-up signals; modulating the first set of wake-up signals using on/off keying (OOK) modulation, wherein each of the first set of wake-up signals is to activate a primary radio located in a respective wireless communication device of the first set of wireless communication devices; transmitting the packet using frequency division multiplexing, FDMA, wherein each of the first set of wake-up signals is transmitted over a respective sub-channel of the first frequency channel.

Another embodiment of the present invention provides a wireless communication method, including: allocating a specific sub-channel of a first frequency channel for the first group of wake-up signals; wherein the first set of wake-up signals comprises one or more wake-up signals; allocating a specific sub-channel of a second frequency channel for the second group of wake-up signals; wherein the second set of wake-up signals comprises one or more wake-up signals; modulating the first and second sets of wake-up signals using on/off keying (OOK) modulation, wherein each of the first set of wake-up signals is to activate a primary radio located in a respective one of the first set of wireless communication devices; each of the second set of wake-up signals is for activating a primary radio located in a respective wireless communication device of a second set of wireless communication devices; transmitting a packet containing the first set of wake-up signals and the second set of wake-up signals by using frequency division multiplexing, FDMA, wherein each of the first set of wake-up signals is transmitted over a particular sub-channel of the first frequency channel and each of the second set of wake-up signals is transmitted over a particular sub-channel of the second frequency channel.

Yet another embodiment of the present invention provides a wireless communication device, including: a memory, a processor coupled with the memory; and a transceiver coupled to the memory, wherein the transceiver is configured to generate a packet comprising a first set of wake-up signals, the generating the packet comprising the first set of wake-up signals being performed by: allocating a subchannel of a first frequency channel for each of the first set of wake-up signals; and modulating the first set of wake-up signals using OOK modulation, wherein each of the first set of wake-up signals is to activate a primary radio located in a respective wireless communication device of the first set of wireless communication devices; and a transceiver for transmitting the packet using FDMA, wherein each of the first set of wake-up signals is transmitted over a respective sub-channel of the first frequency channel.

Yet another embodiment of the present invention provides a wireless communication device, including: a memory, a processor; and a primary radio for transmitting and receiving data packets in an operational mode; and a wake-up radio coupled to the primary radio and including an OOK detector, wherein the wake-up radio is to: receiving a packet comprising a wake-up signal modulated using OOK, wherein the packet comprises a first set of wake-up signals transmitted with FDMA, wherein the first set of wake-up signals are directed to a first set of wireless communication devices; and generating a wake-up indication according to a wake-up signal in the packet, wherein the wake-up indication is used for indicating the primary wireless transceiver to exit from a low-power mode and enter the operation mode.

Accordingly, the system disclosed herein activates the primary radios on multiple communication devices in a WLAN by having the transmitter send a single wake-up packet to provide a protocol for communication of an active wake-up signal. The protocol uses a single modulation mechanism for the wake-up signal and a low interference bandwidth allocation mechanism, which facilitates low cost and low power design of the WUR.

Embodiments of the invention use FDMA to transmit multiple wake-up signals to a wake-up Wireless (WUR) of multiple receiving devices in a single packet, wherein the wake-up signals are modulated using ON/OFF key (OOK) modulation. The WUR according to embodiments of the invention operates in a narrow band. In a multiuser wake-up packet, a frequency channel can be divided into several subchannels for transmitting multiple wake-up signals using FDMA. For example, a frequency channel of 20MHz bandwidth can carry two or three OOK wake-up signals directed to two receiver devices, and each wake-up signal occupies a particular 4MHz sub-channel, which can be determined by a previous negotiation procedure with the transmitting device. Simple OOK modulation and the use of FDMA transmission help to improve the spectrum efficiency of transmitting the wake-up signal.

Two Adjacent wake-up signals are sufficiently separated by a particular frequency separation, e.g., 4MHz or 2MHz, to reduce Adjacent Channel Interference (ACI). The reduced ACI helps to reduce the performance requirements of analog baseband filters in the WUR, resulting in simplified circuit design and reduced development and manufacturing costs.

Once the WUR on the receiver device receives the packet, the WUR converts the OOK wake-up signal into a wake-up indication to wake up the host wireless transceiver device for data communication. This does not require frequent waking up of the primary radio to check whether there are any data communication tasks, with the associated power consumption being reduced. Furthermore, since sending a single packet can wake up multiple communication devices, it helps to reduce the average delay in sending and processing the wake-up signal in a WLAN.

In some examples, the MU wake-up packet may include a series of multiple wake-up signals transmitted using the same sub-channel and concatenated (cascoded) in the time domain. In addition to the OOK wake-up signal, a data frame is also included in the MU wake-up packet and the data frame is directed to the receiver device whose primary radio is already active. Optionally, a reconfiguration window may be inserted between successive wake-up signals on the same subchannel.

In some examples, the MU wake-up packet includes a legacy preamble (legacy preamble) for preventing legacy devices from sending signals during transmission of the wake-up packet.

Since the transceiver in the transmitting device typically needs a reset (resettle) time from the generation of a waveform of one wake-up signal to the generation of another wake-up signal, and from the generation of a waveform of the preamble to the generation of a waveform of the wake-up signal, a reconfiguration window may be inserted between different types of waveforms in the time domain, for example, a reconfiguration window is inserted between a conventional preamble and a wake-up signal, and/or an interval window is inserted between two wake-up signals as a reconfiguration window.

The foregoing is a summary that is illustrative only and is not intended to be in any way limiting. The inventive features and advantages of the present invention, as defined by the claims, will become apparent in the non-limiting detailed description set forth below.

Drawings

Embodiments of the present invention will be best understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein like reference numerals identify like elements.

Fig. 1 is an exemplary WLAN, in which an AP can send a MU wake-up packet to wake up a master wireless transceiver device of a plurality of non-AP Stations (STAs);

FIG. 2 is an exemplary format of a MU wake-up packet for carrying multiple wake-up signals and a single wake-up signal, provided by an embodiment of the present invention;

fig. 3 is an exemplary format of a MU wake-up packet including OOK wake-up signals concatenated in the time domain and transmitted by FDMA according to an embodiment of the present invention;

fig. 4 is a format of an exemplary MU wake-up packet carrying an OOK modulated wake-up signal according to an embodiment of the present invention;

fig. 5A is an exemplary format of a MU wake-up packet provided by an embodiment of the present invention, which includes a reconfiguration window inserted between a legacy preamble and an OOK wake-up signal directed to two receiver Stations (STAs);

fig. 5B is an exemplary format of a MU wake-up packet provided by an embodiment of the present invention, where the MU wake-up packet includes a gap window (also referred to as a gap symbol) inserted between OOK wake-up signals and a guard symbol (spooff symbol) inserted between a conventional preamble and OOK wake-up signal sequence;

fig. 6A and 6B are exemplary multiplexing mechanisms for frequency subchannels used to transmit multiple OOK wake-up signals in FDMA in a MU wake-up packet according to embodiments of the present invention;

fig. 7A and 7B illustrate exemplary frequency band usage for OOK wake-up signal transmission in MU wake-up packets according to an embodiment of the present invention;

fig. 8A is a flowchart of an exemplary process for sending a MU wake-up packet according to an embodiment of the present invention;

fig. 8B is an exemplary sending module, according to an embodiment of the present invention, for generating a plurality of wake-up signal waveforms contained in the MU wake-up packet;

fig. 9A is a flowchart of an exemplary process of waking up an inactive primary wireless transceiver device of a STA in response to a wake-up signal included in a MU wake-up packet according to an embodiment of the present invention;

fig. 9B is a schematic diagram of an exemplary WUR capable of processing a MU wake-up packet to activate a master wireless transceiver device in accordance with an embodiment of the present invention;

fig. 10 is a block diagram of an exemplary wireless communications device capable of generating a MU wake-up packet according to an embodiment of the present invention;

fig. 11 is a block diagram of an exemplary wireless communication device including a WUR capable of activating a master wireless transceiver device in response to a MU wake-up packet provided by an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims. Furthermore, in the following detailed description of embodiments of the invention, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be recognized by one skilled in the art that the present invention may be practiced without these specific details. In other instances, well-known methods, procedures, components and circuits have not been described in detail as not to unnecessarily obscure embodiments of the present invention. Although the method may be depicted as a sequence of numbered steps for clarity, the numbering does not necessarily indicate the order of the steps. It should be understood that some steps may be skipped, performed in parallel, or performed without the requirement of maintaining a strict order of sequence. The drawings showing embodiments of the invention are semi-diagrammatic and may not be to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown exaggerated in the drawing figs.

Sending a Multi-User (MU) Wake-Up Signal in a WLAN by Using FDMA mechanisms

In general, the disclosed embodiments provide a communication protocol for sending and receiving MU wakeup packets that include wakeup signals directed to multiple receiving devices. In a Wireless Local Area Network (WLAN), when a transmitting device attempts to wake up a plurality of receiving devices from a sleep mode, the transmitting device generates a MU wake-up packet having a wake-up signal modulated with OOK. Each OOK modulated wake-up signal is mapped to a particular frequency subchannel and transmitted in FDMA. After receiving the MU wake-up packet, the wake-up wireless transceiver device WUR in the receiving device may identify the wake-up signal directed to the current receiving device and wake up the master wireless transceiver device in the device accordingly.

A communication device disclosed in accordance with an embodiment of the present invention may have a primary radio configured to use one or more wireless communication technologies (e.g., bluetooth, WI-FI, and/or cellular technologies, such as LTE, 4G, 5G, etc.).

Fig. 1 is a diagram illustrating an exemplary WLAN100 provided by an embodiment of the present invention, wherein an Access Point (AP) may transmit a MU wake-up packet 111 to wake up a master wireless transceiver device of a plurality of non-AP Stations (STAs) in the WLAN 100. AP110 and STA 1120, STA 2130 and STAn140 may belong to a Basic Service Set (BSS). Each of STA 1120, STA 2130, and STA n140 has a master wireless transceiver and a low power wake up wireless transceiver (LP-WUR). For example, to conserve power, the primary wireless transceiving device 122 in STA 1120 may be powered down or placed in a sleep state or otherwise inactive state. In this state, the primary wireless transceiver 122 cannot receive or transmit packets. When the master wireless transceiver device is in an inactive state, the WUR 121 remains in an active state and can receive a wake-up signal transmitted from another device (e.g., AP 110). The WUR 121 switches the host wireless transceiver back to the active state in response to the received wake-up signal.

According to an embodiment of the present invention, the AP110 may identify a plurality of STAs that need to be activated, e.g., for receiving data or transmitting data. AP110 then generates a MU wake-up packet 111 with wake-up signals for a plurality of intended STAs. In this manner, more than one STA may receive the wake-up signal simultaneously and process their own wake-up signal independently and simultaneously, respectively. From the AP's perspective, this may help to significantly reduce the number of channels to access the AP and reduce the latency of waking up multiple STAs.

To achieve full WLAN range coverage, the WUR preferably operates on a narrow band. For example, the frequency bandwidth for transmitting the wake-up signal may be 1MHz, 2MHz, 4MHz, or 5 MHz. As described below, a typical frequency channel allocated for transmitting data may be divided into several sub-channels, and the selected sub-channel may be used to carry a (carry) wake-up signal. However, it should be understood that any reasonable bandwidth may be used to transmit the wake-up signal without departing from the scope of the present disclosure.

It should be further appreciated that the particular frequency band allocated to a STA may be determined through a negotiation and/or training procedure between the STA and the AP. The negotiation process may be performed by the STA's master wireless transceiver device when the STA's master wireless transceiver device is in an active state, or the negotiation process may be performed by the WUR itself. The wakeup signal of a particular STA is fixed on the negotiated frequency band, which may be changed by a new negotiation and/or training procedure according to a particular negotiation protocol.

In accordance with the present invention, the AP110 is configured to modulate the wake-up signal using OOK modulation in the allocated sub-channels. In general, OOK modulation is the simplest form of Amplitude-Shift Keying (ASK) modulation representing digital data in the presence or absence of a carrier. AP110 may transmit multiple OOK modulated wake-up signals in a MU wake-up packet via FDMA. A WUR receiving a MU wake-up packet may determine whether the packet contains a wake-up signal intended for the current STA, where the current STA refers to the STA where the WUR is located, based on whether a carrier is present in the expected frequency subchannel. Due to the simple OOK modulation using the wake-up signal, the WUR disclosed in accordance with embodiments of the present invention may have a relatively simple and power-saving configuration, as the circuitry for processing the OOK signal may be low-power and low-cost. In addition, the use of simple OOK modulation and FDMA transmission for multiple users helps to improve spectrum usage efficiency and time efficiency.

To further reduce power consumption of the STA, the WUR itself may have a sleep protocol. For example, WURs need to periodically stay awake for a period of time after a sleep window ("WUR sleep window") ("WUR awake window"). The duration of the awake window may be determined based on the transmission duration of the awake signal, the number of STAs in the basic service set having WURs, and the power consumption requirements of the WURs. For example, the WUR awake window may be set to 2ms to 20 ms. To ensure low latency for responding to the wake-up signal, the WUR sleep window should be relatively short, e.g., 90 milliseconds. Preferably, the WUR sleep window is set to be different from the beacon (beacon) interval to avoid collision between the beacon and the wake-up signal. The WUR sleep protocol may be determined through negotiation with the AP or a coordination process with the AP.

In some embodiments, the MU wake-up packet includes a legacy preamble (legacy preamble) that is used to spoof legacy devices that are not configured to process the MU wake-up packet, for example, because these legacy devices lack a WUR. The legacy preamble carries information about the length of the MU wakeup packet and informs the legacy devices receiving the packet to refrain from sending signals during the packet transmission of the MU wakeup packet. The legacy devices may be High Throughput (HT) devices, Very High Throughput (VHT) devices, and High Efficiency (HE) devices defined in various IEEE802.11 standards, or any other type of legacy devices.

In addition, the wake-up signal in the MU wake-up packet may include a wake-up preamble (wake-up preamble) containing a signature sequence of the wake-up signal, an ID of the receiving STA, an ID of the basic service set, an ID of the AP, a data part and a length part (the length part is optional), a Frame Check Sequence (FCS), and/or any other suitable fields and information. In some embodiments, instead of the ID of a specific STA, the wake-up preamble in the wake-up beacon in the MU wake-up packet includes a group ID for identifying a group of STAs of the plurality of receiving STAs, i.e., the wake-up beacon is directed to a group of STAs, and the group of STAs, upon receiving the wake-up beacon, wake up the respective primary wireless transceiver devices, e.g., all STAs in the home network. Well-known fields and information that may be included in the MU wake-up packet are omitted from the figures and description for the sake of brevity. The wake-up preamble may be located in the wake-up signal, or may be located in other parts of the packet, such as the preamble of the packet.

Fig. 2 illustrates an exemplary format of a MU wake-up packet for carrying multiple wake-up signals and a single wake-up signal provided in accordance with an embodiment of the present invention. The MU wake-up packet 200 includes a legacy preamble 210 transmitted in a frequency channel of 20MHz bandwidth. Two wake-up signals 211 and 212 directed to station # k and station # m with WURs follow the legacy preamble. The wake-up signals 211 and 212 are OOK modulated and transmitted using FDMA over two sub-channels (e.g., 4MHz in each sub-channel) that each occupy 20MHz of bandwidth. In the case where only one STA needs to be woken up, the AP may generate a Single User (SU) wake-up packet by using the same format. Therefore, only one OOK wake-up signal is transmitted to the intended single STA # m, as shown at 220.

In some embodiments, sending the MU wake-up signal may use a combination of FDMA and a time-domain cascading scheme. By cascading transmit wakeup signal sequences, the AP may wake up multiple STAs with WURs operating on the same sub-channel. Fig. 3 illustrates an exemplary format of a disclosed MU wakeup packet 300 with OOK wakeup signals concatenated in the time domain sent with FDMA in accordance with an embodiment of the present invention. As shown, STA # k1 and STA # k2 are allocated with the same sub-channel for the wake-up signal. Similarly, STA # m1 and STA # m2 share the same sub-channel, and STA # n1 and STA # n2 share the same sub-channel. Each subchannel carries a plurality of wake-up signals arranged in cascade in the time domain. For example, the first sub-channel 311 carries a wake-up signal for STA # k1, followed by a wake-up signal for STA # k1, followed by a wake-up signal for STA # k 2. In this configuration, a number of STAs greater than the number of available subchannels may be awakened using the MU wake-up packet, thereby further improving the time efficiency of transmitting the wake-up signal in the basic service set. Accordingly, the duration field in the SIG field of the legacy preamble should be large enough to protect the transmission of all concatenated wake-up sequences.

In some embodiments, the MU wake-up packet may combine multiple wake-up signals for waking up some inactive STAs and data frames directed to the active STAs. The active STA is configured with a WUR and has entered an active state in response to a wake up indication generated by the WUR. Alternatively, an active STA may only have a primary radio that remains active at all times during operation of the STA.

Fig. 4 illustrates the format of an exemplary MU wake-up packet 400 carrying an OOK modulated wake-up signal 412 and a data frame 413 provided by an embodiment of the present invention. For example, a High Efficiency (HE) STA # k compliant with the ieee802.11ax standard is in an active state and is a receiving device of an expected data frame. The data frame is modulated with OFDMA modulation. The packet has a HE preamble 411, which HE preamble 411 contains the required signaling for HE STA # k. However, the MU wake-up packet provided by embodiments of the present invention may include one or more data frames for any other suitable type of STA, e.g., data frames for HE STA # x or data frames for HE STA # k.

The wake-up signal 412 uses OOK modulation or FSK modulation and is intended for inactive STAs with WUR. For example, the wake-up signal 412 is a wake-up signal for STA # m with WUR. It should be appreciated that the present invention is not limited to the number of wake-up signals and the number of data frames contained in the MU wake-up packet. When a plurality of OOK wake-up signals are included in the wake-up packet, the plurality of OOK wake-up signals are transmitted using FDMA. Due to the use of different types of modulation, the wake-up signal and the data frame may potentially interfere with each other. The receiving STA may reduce or eliminate interference using filtering and/or rate adaptation, which may be implemented in any manner known in the art.

In some embodiments, a reconfiguration window may be inserted between a legacy preamble (e.g., legacy/HT-VHT/HE preamble) and a subsequent wake-up signal. The reconfiguration window helps provide a reset period for the transmitter to adjust its configuration from producing one type of waveform adjustment to producing another type of waveform, such as power, bandwidth, and RF/analog circuit settings. For example, the duration of the window may correspond to a transition period during which the transmitter switches from generating a waveform for the legacy preamble to generating a waveform for the wake-up signal. Signals transmitted in this reconfiguration window are considered unreliable and are not processed by the receiving STA as valid signals. Fig. 5A shows a format of a MU wake-up packet 510 provided by an embodiment of the present invention, where the MU wake-up packet 510 includes a reconfiguration window 514 inserted between a legacy preamble 511 and OOK wake-up

signals

512 and 513 directed to two receiving STAs. The reconfiguration window 514 may also serve as a protection symbol for a particular level of legacy devices, such as legacy devices that comply with the IEEE802.11 n standard. The guard symbol allows the device that monitors the packet to consider the packet to be an IEEE802.11 n packet and not to send it. The reconfiguration symbols may be generated using Binary Phase Shift Keying (BPSK) modulation.

Fig. 5B illustrates an exemplary format of a MU wake-up packet 520 provided by an embodiment of the present invention, where the MU wake-up packet 520 includes an exemplary interval window 525 inserted between OOK wake-up signals and guard symbols 524 inserted between a legacy preamble 521 and an OOK wake-up signal sequence. As shown, packet 520 carries OOK wake-up signals concatenated in the time domain using FDMA. One subchannel is used to transmit a sequence of wake-up signals directed to multiple receiving STAs. The guard symbol 524 inserted between the legacy preamble 521 and the wake-up signal is also used as a reset period of the transmitter, see fig. 5A described above. In addition, an interval window (e.g., 525) is also inserted between the transmission of two adjacent wake-up signals (522,523) on the same sub-channel. For example, the time of the interval window 525 may be much smaller than the time of the guard symbol 524. Wherein the spacing window 525 is used to space apart two adjacent wake-up signals. The time of the interval window 525 may correspond to a reset (resettle) time from the generation of the waveform of one wake-up signal to the generation of the waveform of another wake-up signal. The role of the guard symbols in this and subsequent figures may be the same as that of the guard symbols in fig. 5A, or the same as that of the reconfiguration window 514 in fig. 5A.

Because the WURs provided by embodiments of the present invention may operate in a narrow band, the frequency channel may be divided into several sub-channels that are used to transmit multiple wake-up signals using FDMA. Fig. 6A-6B illustrate an exemplary multiplexing mechanism for frequency subchannels used to transmit multiple OOK wake-up signals in a MU wake-up signal packet using FDMA, provided by embodiments of the invention. Fig. 6A shows that the 20MHz frequency channel is evenly divided into 4MHz sub-channels, and two

middle sub-channels

611 and 612 are used to transmit the wake-up signal. The two sub-channels 611 and 612 are separated by a frequency interval of 4MHz to reduce interference between each other, and the edge sub-channel is not used. Figure 6B shows that the 20MHz frequency channel is unevenly divided into three 4MHz subchannels and four 2MHz subchannels, where each 4MHz subchannel is used to send a wake-up signal using FDMA and the 2MHz subchannels are used as the frequency spacing between wake-up signals. The edge 2MHz subchannel is unused.

Adjacent Channel Interference (ACI) is advantageously reduced by using a sufficient frequency separation to separate two Adjacent wake-up signals, wherein the frequency separation is either 4MHz or 2 MHz. The reduced adjacent channel interference results in reduced performance requirements for analog baseband filters in the WUR, thus simplifying circuit design and reducing development and manufacturing costs of the WUR.

Fig. 7A and 7B are schematic diagrams illustrating exemplary frequency bands used for transmitting an OOK wake-up signal in an MU wake-up packet according to an embodiment of the present invention. Fig. 7A shows using FDMA, a 40MHz bandwidth for transmission of two wake-up signals for STA # n and STA # m, each wake-up signal following a legacy preamble and guard symbol. The 40MHz bandwidth is divided into 220 MHz frequency channels and two preambles each transmitted in one channel. For each frequency channel, a subchannel is used to transmit an OOK wake-up signal. Similarly, fig. 7B shows that 4 wake-up signals are transmitted to STAs # n, # m, # k, and # I using FDMA with an 80MHz bandwidth. Each wake-up signal follows a conventional preamble and guard symbol. At each 20MHz frequency channel, a subchannel is used to transmit an OOK wake-up signal. Wherein, at each 20MHz frequency channel, one or more sub-channels may be used to transmit the OOK wake-up signal. Specifically, the OOK wake-up signal may be transmitted only by using the middle sub-channel of the 20MHz frequency channel, for example, the OOK wake-up signal may be transmitted only by using the middle 4MHz sub-channel of the 20MHz frequency channel, for example, in fig. 6A, the 20MHz frequency channel is divided into multiple 4MHz, only the middle 4MHz is used as the sub-channel to transmit the OOK wake-up signal, and the other frequency parts do not transmit the OOK wake-up signal; or, for example, in fig. 6B, the middle 4MHz sub-channel is used to transmit the OOK wake-up signal, and the other frequency parts do not transmit the OOK wake-up signal. The above is merely an example, and the present invention is not limited thereto, and multiple sub-channels may be used to transmit the OOK wakeup signal in each 20MHz frequency channel. It should be noted that the 80MHz bandwidth shown in fig. 7B is divided into 4 20MHz bands, and although fig. 7B shows that an OOK wake-up signal is transmitted on each 20MHz band, in other embodiments, a certain 20MHz band may not transmit an OOK wake-up signal, for example, the first 20MHz band and the third 20MHz band of the 80MHz band transmit an OOK wake-up signal, and the second 20MHz band does not transmit an OOK wake-up signal.

Fig. 8A is a flowchart of an exemplary process 800 for sending a MU wake-up packet according to an embodiment of the present invention. Process 800 may be performed by an AP, or any other suitable wireless communication device that transmits a wake-up signal over a WLAN to wake-up an inactive wireless communication device.

At 801, a negotiation procedure is performed to coordinate communication between a sending device and a receiving device with respect to a MU wake-up packet, e.g., by a primary wireless transceiver device of an AP. The negotiation between the AP and the receiving STA may determine parameters for various aspects to be used in the MU wake-up packet transmission, such as center frequency, frequency bandwidth, OOK modulation parameters, sleep protocol for WUR, etc. The negotiation process may involve the host wireless transceiver of the WUR or the receiving STA. It will be appreciated that renegotiation may be performed under various suitable circumstances, such as periodically or in response to user instructions or certain events (e.g., introduction of a new STA) to renegotiate.

At 802, the AP identifies one or more STAs that the primary wireless transceiver device needs to wake up to perform data communications, such as receiving downlink data packets, sending uplink data packets, or transmitting packets with other peer STAs. At 803, a MU wake-up packet is generated that includes wake-up signals directed to the plurality of identified STAs. Each wake-up signal is modulated using OOK/FSK modulation and mapped to a negotiated frequency subchannel. As previously described, more than one wake-up signal may be configured to the same frequency subchannel and cascaded in the time domain. If there is only one STA that needs to wake up, a single-user SU packet can be generated by using the same packet format. Also, the MU wakeup packet also includes one or more data frames directed to the active STA. It is to be understood that generating the MU wakeup packet involves a wide range of signal processing, such as padding (padding), scrambling (scrambling), encoding, parsing, frequency mapping, and so forth.

At 804, a wake-up packet is transmitted via a transmitter and antenna array of the AP device. The MU wake-up packet is sent to the identified STAs, for example, using FDMA. The aforementioned 802-804 can be repeated periodically, or the aforementioned 802-804 can be triggered by some event, according to a scheduling algorithm.

The present invention does not limit a method of generating the waveform of the OOK wakeup signal for FDMA in the transmitter. In some embodiments, such waveforms can be generated in a baseband module (e.g., a primary wireless transceiver using an AP) and then digitally modulated into corresponding sub-channels of narrow bandwidth. Each sub-channel may contain at least one OOK wake-up signal and each wake-up signal is used to wake-up a STA with a WUR.

Fig. 8B illustrates an exemplary transmitter module for generating a waveform for a plurality of wake-up signals included in a MU wake-up packet according to an embodiment of the present invention. For example, the transmitter may be a transmitter in STA # k. The transmitter (not explicitly shown) has parallel processing paths 860,870, and 880, which processing paths 860,870, and 880 operate in parallel to generate a plurality of wake-up signals. Each path includes OOK baseband circuitry, pulse shaping circuitry, and digital mixers for a respective sub-channel. For example, for a wake-up signal directed to STA # k (or WUR # k), OOK baseband circuitry 861 modulates a carrier signal using OOK modulation and generates a baseband OOK signal. The pulse shaping circuit 862 adjusts the waveform of the baseband OOK signal so that the signal is suitable for the frequency subchannel #1 allocated thereto. Digital mixing circuit 863 in processing path 860 mixes the digital signals for use in frequency subchannel # 1. Digital mixing circuitry in processing path 870 mixes the digital signals for use in frequency subchannel # 2. Digital mixing circuitry in processing path 880 mixes the digital signals for use in frequency subchannel # D. The signals of the various sub-channels are then combined in adder 881, and the combined signal is provided to DAC882 for digital-to-analog conversion and then to downstream logic (not shown). The resulting analog signal is then transmitted through an antenna array using FDMA.

Fig. 9A is a flowchart of an exemplary process for waking up an inactive primary wireless transceiver device of a STA in response to a wake-up signal included in a MU wake-up packet according to an embodiment of the present invention. Process 900 may be performed by a WUR coupled to a host wireless transceiver device. Corresponding to 801 in fig. 8A, at 901, a negotiation procedure is performed to coordinate communication between a sender device (e.g., a master wireless transceiver device in an AP) and a WUR of a STA with respect to a MU wake-up packet. The negotiation between the AP and the STA may obtain various aspects of parameters to be used in subsequent MU wake-up packet transmissions, such as center frequency, frequency band, OOK modulation parameters, sleep protocol for WUR, and so on. Renegotiation may occur under various suitable circumstances, such as introduction of a new STA to the WLAN may cause renegotiation or renegotiation in response to user instruction, which may be periodic, for example.

In this example, the WUR employs a sleep protocol as described above. At 902, the WUR wakes up at the wake window. At 903, the WUR receives the MU wake-up packet over the WLAN. At 904, the WUR identifies the received packet as an FDMA OOK wake-up packet and identifies the current STA as the intended receiver, according to the preamble in the packet. For example, the wake-up preamble in the wake-up signal in the packet specifies the wake-up signature sequence, the ID of the AP, the group ID of the target STA, the ID of the current STA, and so on. Wherein the current STA may be the STA where the WUR is located. At 905, the WUR identifies and processes a particular wake-up signal in the MU packet directed to the current STA. At 906, a wake-up indication is generated based on the wake-up signal. At 907, a wake up indication is sent to the primary radio, which is activated and ready for data transmission activity in response. Optionally, the wake-up preamble of the wake-up signal may specify an ID of a certain STA, which indicates that the wake-up signal is directed to the STA identified by the ID, and a subsequent WUR in the STA sends a wake-up instruction to the host wireless transceiver, or the wake-up preamble of the wake-up signal may specify a group ID, that is, a group ID of an STA group, which indicates that the wake-up signal is directed to a group of STAs corresponding to the ID, where the group of STAs includes multiple STAs, and the WURs of the subsequent STAs in the STA group send wake-up instructions to the corresponding host wireless transceiver.

Fig. 9B is an exemplary WUR950 capable of processing MU wake-up packets to activate a master wireless transceiver device in accordance with an embodiment of the present invention. The MU wake-up packet includes an FDMA OOK wake-up signal. The WUR includes an Automatic Gain Controller (AGC) 951, an RF local oscillator 952, a mixer 953, a Low Pass Filter (LPF) 954, an analog-to-digital converter (ADC)955, and an OOK signal detector 956.

The WUR950 is able to receive the signal of the MU wake-up packet through a receive antenna (not shown). AGC951 includes an Attenuator (ATT) that controls the amplitude or gain of the received signal. A filter (not shown) filters the RF signal and an RF local oscillator oscillates out the RF frequency while switching the RF frequency to the center frequency of the wake-up signal directed to the WUR950 and outputs the RF local oscillation frequency, which is substantially the same as or close to the center frequency of the wake-up signal, to the mixer 953. The mixer 953 converts the RF signal from the filter into a baseband signal by using the RF local oscillation frequency output from the RF local oscillator 952. The LPF954 adjusts the filtering bandwidth of the filter to the bandwidth of the wake-up signal according to the bandwidth of the wake-up signal determined by the previous negotiation process, and filters the baseband signal provided by the mixer 953. The ADC955 converts the analog baseband signal output from the LPF954 into a digital baseband signal.

OOK signal detector 956 demodulates the digital baseband signal output from ADC 955. The WUR can determine whether the MU wake-up packet carries an OOK wake-up signal in a particular sub-channel directed to the current STA, depending on whether the energy can be determined in the filtered analog signal. In particular, if the OOK signal detector 956 detects energy in a particular frequency subchannel, a wake-up indication is generated for waking up the primary wireless transceiver device.

Fig. 10 is a block diagram of an exemplary wireless communications device 1000 capable of generating a MU wake-up packet according to an embodiment of the present invention. The communication device 1000 may be an AP or a non-AP with a transceiver for data communication, such as a general purpose computer, a smartphone, a tablet wearable device, a detector used on the Internet of things (IoT), and so on.

The device 1000 includes a main processor 1030, a memory 1020, and a transceiver 440 coupled to the

antenna array

1001 and 1004. Memory 1020 includes a wake manager 1021 storing processor-executable instructions for generating wake signals and other partial configurations of MU wake-up packets, as described in detail in FIGS. 1-8A. The wake-up manager 1021 also stores other information related to wake-up packet generation and management, such as the ID of the STA, the group ID of the group of STAs, the sleep protocol of the master wireless transceiver device and the WUR of the STA, the negotiation protocol, the frequency sub-channel assigned to each WUR, the MU wake-up packet format, and so on. In some other embodiments, wake manager 1021 is stored in a memory in transceiver 1040.

The transceiver 1040 includes an OOK baseband module 1041, a pulse shaping module 1042, and a digital mixing module 1043, which operate to generate an OOK wake-up signal for transmitting the OOK wake-up signal with FDMA as described in detail in fig. 8B. The transceiver 1040 further includes various modules for generating a transmit path for each portion of a MU wake-up packet or data packet or any other type of communication transmission unit. For example, there is a transmit First-In-First-Out (TX FIFO) module 1044, an encoder 1046, a scrambler 1045, an interleaver 1048, a constellation mapper 1047, an Inverse Discrete Fourier Transformer (IDFT) 1049, and a Guard Interval (Guard Interval, gi) and window insertion module 1050. Specifically, the OOK baseband module 1041 is configured to modulate a carrier signal using OOK modulation and generate a baseband OOK signal; the pulse shaping module 1042 is configured to shape a baseband OOK signal, the digital mixing module 1043 mixes the digital signal output by the pulse shaping module 1042, and the mixed signal is processed by one or more of the transmit first-in first-out module 1044, the encoder 1046, the scrambler 1045, the interleaver 1048, the constellation mapper 1047, the inverse discrete fourier transformer 1049, and the GI and window insertion module 1050 and then transmitted. The GI and window insertion module 1050 may insert at least one of the reconfiguration window 514, the guard symbol 524, and the interval window 525 in the WU wakeup packet.

Fig. 11 is an exemplary wireless communication device 1100, the wireless communication device 1100 including a WUR1150 capable of activating a host wireless transceiver device in response to a MU wake-up packet, according to an embodiment of the present invention. The device 1100 may be a STA that is not an AP and performs data communication with other devices through a wireless local area network. The device 1100 may be a general purpose computer, a smartphone, a tablet wearable device, a detector in the IoT, and so on.

The device 1100 includes a host processor 1130, a memory 1120, and a transceiver 1140 coupled to an antenna 1101. The transceiver includes a primary wireless transceiver 1141 that operates to enter an inactive state to conserve power. The WUR1150 is capable of processing the MU wake-up packet and generating an indication accordingly to activate the host wtru 1141, as described in detail in relation to fig. 9A. In particular, the WUR1150 includes an AGC 1151, a mixer 1152, an LPF 1153, and an OOK signal detector 1154, as described in detail in relation to fig. 9B.

Various modules in the primary wtru 1141 are used to process received data packets or any other type of communication transmission unit. As shown, the primary radio includes a receive First-In-First-Out (RX FIFO)1142, a synchronizer 1143, a channel estimator and quantizer 1144, a decoder 1146, a demapper 1145, a deinterleaver 1149, a Fast Fourier Transformer (FFT) 1148, and a descrambler (descrambler) 1147.

The various modules in the primary radio 1141 are used to process received data packets or any other type of communication transmission unit. As shown, the primary radio includes an RX FIFO 1142, a synchronizer 1143, a channel estimator and quantizer 1144, a decoder 1146, a demapper 1145, a deinterleaver 1149, a Fast Fourier Transformer (FFT) 1148, and a descrambler (descrambler) 1147.

It is to be appreciated that transceiver 1040 in fig. 10 and transceiver 1141 in fig. 11 may include a wide range of other suitable components known in the art. The various components may be implemented in any suitable manner known in the art and may be implemented using hardware, firmware, and software logic or any combination thereof. Further, in some embodiments, the transceiver 1040 in fig. 10 may also include components in the receive path as described in more detail with reference to the primary radio 1141 in fig. 11, and vice versa.

Although certain preferred embodiments and methods have been disclosed herein, variations and modifications of these embodiments and methods may be effected by those skilled in the art without departing from the spirit and scope of the invention, and any modifications which do not depart from the spirit and scope of the invention are intended to be covered by the claims appended hereto.

Claims

1. A method of wireless communication, the method comprising:

generating a packet comprising a first set of wake-up signals, wherein the generating a packet comprising a first set of wake-up signals comprises:

allocating a subchannel of a first frequency channel for each of the first set of wake-up signals;

modulating the first set of wake-up signals using on/off keying (OOK) modulation, wherein each of the first set of wake-up signals is to activate a primary radio located in a respective wireless communication device of the first set of wireless communication devices;

transmitting the packet using frequency division multiplexing, FDMA, wherein each of the first set of wake-up signals is transmitted over a respective sub-channel of the first frequency channel.

2. The method of claim 1, wherein a frequency spacing between subchannels of each two adjacent wake-up signals of the first set of wake-up signals is equal to a bandwidth of a subchannel to which wake-up signals are allocated, wherein subchannels located at upper and lower ends of the first frequency channel are unused.

3. The method of claim 1, wherein the first frequency channel has a bandwidth of approximately 20MHz, and wherein each of the first set of wake-up signals is configured to have a bandwidth of approximately 4 MHz.

4. The method of claim 1, wherein the packet further comprises a legacy preamble, the legacy preamble configured to prevent legacy devices from transmitting signals during transmission of the packet, wherein the legacy preamble is transmitted over the first frequency channel, wherein generating the packet comprising the first set of wake-up signals further comprises: inserting a reconfiguration window between the legacy preamble and a wake-up signal, wherein the reconfiguration window corresponds to a transition period during which a transmitter switches from a waveform that generates the legacy preamble to a waveform that generates the wake-up signal.

5. The method of claim 1, further comprising: generating another packet comprising a single wake-up signal for activating a wireless communication device of the first group of wireless communication devices, wherein the single wake-up signal is transmitted over an allocated subchannel of the first frequency channel;

or,

the package further comprises: a second set of wake-up signals for activating a primary radio located in a second set of wireless communication devices, wherein generating the packet further comprises: assigning a subchannel of a second frequency channel to each of the second set of wake-up signals, wherein each of the second set of wake-up signals is transmitted over a respective subchannel of the second frequency channel.

6. The method of claim 1, wherein the packet further comprises a second wake-up signal operable to activate a primary radio of a plurality of wireless communication devices in a third group of wireless communication devices.

7. The method of claim 6, wherein a first wake-up signal and the second wake-up signal in the first set of wake-up signals are assigned with the same sub-channel and are transmitted in a cascaded order in a time domain.

8. The method of claim 1, wherein the packet further comprises a data field pointing to another wireless communication device, and wherein generating the packet comprising the first set of wake-up signals further comprises: the data field is modulated using orthogonal frequency division multiple access, OFDMA, modulation.

9. The method of claim 1, further comprising:

generating another packet comprising a third set of wake-up signals, wherein the generating another packet comprises:

assigning a sub-channel of a respective frequency channel of a plurality of frequency channels to each of the third set of wake-up signals, wherein each of the plurality of frequency channels has a bandwidth greater than or equal to 20MHz, wherein the sub-channel of the respective frequency channel has a bandwidth of 4 MHz; and

modulating the third set of wake-up signals using OOK modulation; and

the other packet is sent using FDMA.

10. The method of claim 1, wherein the first set of wake-up signals comprises a first wake-up signal and a second wake-up signal, the first wake-up signal and the second wake-up signal being allocated to the same subchannel and being cascaded in a time domain; the first wake-up signal is used to activate a primary wireless transceiver in a first wireless communication device of the first group of wireless communication devices, and the second wake-up signal is used to activate a primary wireless transceiver in a second wireless communication device of the first group of wireless communication devices.

11. The method of claim 1, wherein each of the first set of wake-up signals is transmitted over a different subchannel of the first frequency channel.

12. A method of wireless communication, the method comprising:

modulating a first set of wake-up signals and a second set of wake-up signals using on/off keying (OOK) modulation, wherein the first set of wake-up signals comprises one or more wake-up signals; the second set of wake-up signals comprises one or more wake-up signals; wherein each of the first set of wake-up signals is to activate a primary radio located in a respective wireless communication device of the first set of wireless communication devices; each of the second set of wake-up signals is for activating a primary radio located in a respective wireless communication device of a second set of wireless communication devices;

transmitting a packet containing the first set of wake-up signals and the second set of wake-up signals by using frequency division multiplexing, FDMA, wherein each of the first set of wake-up signals is transmitted over a particular sub-channel of a first frequency channel and each of the second set of wake-up signals is transmitted over a particular sub-channel of a second frequency channel.

13. The method of claim 12,

the particular subchannel of the first frequency channel is a subchannel located in the middle of the first frequency channel;

the particular subchannel of the second frequency channel is a subchannel located in the middle of the second frequency channel.

14. The method of claim 13, wherein the first frequency channel and the second frequency channel are each 20MHz bandwidths; the particular subchannel of the first frequency channel and the particular subchannel of the second frequency channel is a 4MHz bandwidth that is the middle of the 20MHz bandwidth.

15. The method of claim 12,

the frequency parts of the first frequency channel except the specific sub-channel are not used for transmitting the wake-up signal; and/or the frequency parts of the second frequency channel except the specific sub-channel are not used for transmitting the wake-up signal.

16. The method of claim 12, wherein an 80MHz bandwidth is divided into 4 20MHz bandwidths, wherein the first frequency channel and the second frequency channel are discontinuous 20MHz bandwidths in the 80MHz bandwidth, and wherein the 20MHz bandwidth between the first frequency channel and the second frequency channel does not transmit a wake-up signal.

17. A wireless communication device, comprising:

a memory for storing a plurality of data to be transmitted,

a processor coupled to the memory; and

a transceiver coupled to the memory, wherein the transceiver is configured to generate a packet comprising a first set of wake-up signals, the generating the packet comprising the first set of wake-up signals being performed by:

allocating a subchannel of a first frequency channel for each of the first set of wake-up signals; and

modulating the first set of wake-up signals using OOK modulation, wherein each of the first set of wake-up signals is to activate a primary radio located in a respective wireless communication device of a first set of wireless communication devices; and

a transceiver configured to transmit the packet using FDMA, wherein each of the first set of wake-up signals is transmitted over a respective sub-channel of the first frequency channel.

18. The wireless communication device of claim 17,

the frequency spacing between the sub-channels of each two adjacent wake-up signals of the first set of wake-up signals is equal to the bandwidth of the sub-channel to which the wake-up signal is allocated.

19. The wireless communications apparatus of claim 17, wherein the packet further comprises: a second set of wake-up signals for activating a primary radio located in a second set of wireless communication devices, wherein the transceiver is further configured to: assigning a subchannel of a second frequency channel to each of the second set of wake-up signals, and wherein each of the second set of wake-up signals is transmitted over a respective subchannel of the second frequency channel.

20. The wireless communications apparatus of claim 17, wherein the packet further comprises: a legacy preamble to prevent legacy devices from transmitting signals during transmission of the packet, wherein the legacy preamble is transmitted over the first frequency channel, wherein the transceiver is further configured to insert a reconfiguration window between the legacy preamble and the first set of wake-up signals.

21. The wireless communication device of claim 17, wherein the transceiver is further configured to generate another packet comprising a single wake-up signal for activating a wireless communication device of the first group of wireless communication devices, wherein the single wake-up signal is transmitted via the allocated sub-channel of the first frequency channel.

22. The wireless communication device of claim 17, wherein the packet further comprises a second wake-up signal, and wherein the second wake-up signal is used to activate the primary radios of a plurality of wireless communication devices in a third group of wireless communication devices.

23. The wireless communication device of claim 22, wherein a first wake-up signal and the second wake-up signal in the first set of wake-up signals are assigned with the same sub-channel and are transmitted in a cascaded order in a time domain.

24. The wireless communications device of claim 17, wherein the packet further includes a data field pointing to another wireless communications device, the generating the packet further comprising: modulating the data field using OFDMA modulation.

25. The wireless communication device of claim 17, wherein the transceiver is further configured to:

modulating the third set of wake-up signals using OOK modulation; and

the other packet is sent using FDMA.

26. The wireless communications device of claim 17, wherein each of the first set of wake-up signals is transmitted over a different subchannel of the first frequency channel.

27. A wireless communication device, comprising:

a memory for storing a plurality of data to be transmitted,

a processor; and

a primary radio for transmitting and receiving data packets in an operational mode; and

a wake-up radio coupled to the main radio and including an OOK detector, wherein the wake-up radio is to:

receiving a packet comprising a wake-up signal modulated using OOK, wherein the packet comprises a first set of wake-up signals transmitted with FDMA, wherein the first set of wake-up signals are directed to a first set of wireless communication devices; and

generating a wake-up indication according to a wake-up signal in the packet, wherein the wake-up indication is used for indicating the primary wireless transceiver device to exit from a low power mode and enter the operation mode.

28. The wireless communications device of claim 27, wherein the wake-up radio is further configured to:

detecting an identifier of the wireless communication device in the packet, wherein the wake-up signal is related to the identifier, and the wake-up signal is transmitted through a sub-channel of a frequency channel; and is

Demodulating the wake-up signal using OOK demodulation.

29. The wireless communication device of claim 27, wherein a frequency spacing between subchannels of each two adjacent wake-up signals in the first set of wake-up signals is equal to a bandwidth of a subchannel to which the wake-up signal is allocated, wherein subchannels at upper and lower ends of the first frequency channel are unused, wherein the wake-up radio further comprises a low pass filter to provide the wake-up signal to the OOK detector.

30. The wireless communications device of claim 27, wherein the packet further comprises a legacy preamble configured to prevent legacy devices from transmitting signals during transmission of the packet, wherein the legacy preamble is transmitted over the first frequency channel, wherein the packet further comprises a reconfiguration window between the legacy preamble and the wake-up signal.

31. The wireless communication device of claim 27, wherein the packet further comprises a second wake-up signal for activating a primary radio of a plurality of wireless communication devices in a third group of wireless communication devices, wherein the wake-up signal and the second wake-up signal are transmitted in the packet by using the same sub-channel and are transmitted in a cascaded sequence in a time domain.

32. The wireless communications device of claim 27, wherein the packet further comprises a data field directed to another wireless communications device, wherein the data field is modulated with OFDMA modulation.