Wireless local area network system

Abstract

The embodiment of the invention provides a wireless local area network system. The wireless local area network system comprises a first Wi-Fi device and at least one second Wi-Fi device. And when the first Wi-Fi device and the at least one second Wi-Fi device receive an interference signal and occupy a current operation channel of the first Wi-Fi device and a current operation channel of the at least one second Wi-Fi device, the first Wi-Fi device performs channel switching on the current operation channel of the first Wi-Fi device. And the at least one second Wi-Fi device carries out channel switching on the current operation channel of the second Wi-Fi device.

Description

Technical Field

[0001] The present application relates to the field of wireless communications, and more particularly, to a wireless local area network (WLAN) system using frequency hopping to avoid co-channel interference. Background Art

[0002] WLANs use radio frequency (RF) signals to communicate between access points (APs) and non-AP stations (STAs). However, these signals may be interfered with by other signal sources, such as other WLANs or Bluetooth (BT) devices. Interference may degrade the performance, reliability, and security of the WLAN. For example, co-channel interference occurs when two or more APs use the same channel or frequency band within overlapping coverage areas. Co-channel interference causes contention and collisions between client devices attempting to access the channel. As a result, co-channel interference reduces WLAN throughput, increases latency, and degrades the signal-to-noise ratio (SNR). From the end user's perspective, the WLAN may appear to be running slowly or not operating at all. Therefore, it is necessary to design an innovative co-channel interference avoidance scheme to improve WLAN performance. Summary of the invention

[0003] One of the objects of the claimed invention is to provide a WLAN system that uses frequency hopping to avoid co-channel interference. For example, a particular frequency hopping operation can improve the throughput and / or latency of the WLAN system.

[0004] According to a first aspect of the present invention, an exemplary WLAN system is disclosed. The exemplary WLAN system includes a first Wi-Fi device and at least one second Wi-Fi device. When the first Wi-Fi device and the at least one second Wi-Fi device receive an interference signal, occupying a current operating channel of the first Wi-Fi device and a current operating channel of the at least one second Wi-Fi device, the first Wi-Fi device switches the current operating channel of the first Wi-Fi device, and the at least one second Wi-Fi device switches the current operating channel of the second Wi-Fi device.

[0005] According to a second aspect of the present invention, an exemplary WLAN system is disclosed. The exemplary WLAN system includes a first Wi-Fi device and at least one second Wi-Fi device. When the first Wi-Fi device and the at least one second Wi-Fi device receive interference signals, occupying a current operating channel of the first Wi-Fi device and a part of a current operating channel of the at least one second Wi-Fi device, the at least one second Wi-Fi device performs a sub-channel switch on the current operating channel of the second Wi-Fi device to switch to a new operating channel, and the new operating channel is included in another part of the operating channels in the current operating channel of the first Wi-Fi device.

[0006] These and other objects of the present invention will no doubt become apparent to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment which is depicted in the various figures and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 is a diagram illustrating a WLAN system supporting the proposed frequency hopping scheme for co-channel interference avoidance according to an embodiment of the present invention.

[0008] Figure 2 is a timing diagram illustrating a frequency hopping scenario with implicit channel switching according to an embodiment of the present invention.

[0009] Figure 3 is a timing diagram illustrating a frequency hopping scenario with implicit channel switching and downlink front end selection (DLFES) according to an embodiment of the present invention.

[0010] Figure 4 is a timing diagram illustrating a frequency hopping scenario with implicit sub-band switching according to an embodiment of the present invention.

[0011] Figure 5 is a timing diagram illustrating a frequency hopping scenario with implicit sub-band switching and downlink front end selection (DL FES) according to an embodiment of the present invention.

[0012] Figure 6 is a timing diagram illustrating a frequency hopping scenario with implicit sub-band switching and uplink front end selection (ULFES) according to an embodiment of the present invention.

[0013] Figure 7 is a timing diagram illustrating a frequency hopping scenario with explicit channel switching and downlink front end selection (DLFES) according to an embodiment of the present invention.

[0014] Figure 8is a timing diagram illustrating a frequency hopping scenario with explicit channel switching and joint transmission according to an embodiment of the present invention.

[0015] Fig. 9 is a timing diagram illustrating a frequency hopping scenario with explicit sub-band switching and downlink front end selection (DLFES) according to an embodiment of the present invention.

[0016] Fig.10 FIG. 1 is a timing diagram illustrating explicit sub-band switching front end selection (FES) according to an embodiment of the present invention.

[0017] Fig.11 FIG. 4 is a flow chart illustrating a dynamic selection mechanism of an AP according to an embodiment of the present invention.

[0018] Fig.12 is a timing diagram illustrating 1-1 actions of an AP determined by the proposed dynamic selection mechanism according to an embodiment of the present invention.

[0019] Fig.13 is a timing diagram illustrating 2-1 actions of an AP determined by the proposed dynamic selection mechanism according to an embodiment of the present invention.

[0020] Fig.14 is a timing diagram illustrating a 2-2 action of an AP determined by the proposed dynamic selection mechanism according to an embodiment of the present invention.

[0021] Fig.15 is a timing diagram illustrating 3-1 actions of an AP determined by the proposed dynamic selection mechanism according to an embodiment of the present invention.

[0022] Fig.16 is a timing diagram illustrating the 3-2 actions of an AP determined by the proposed dynamic selection mechanism according to an embodiment of the present invention. DETAILED DESCRIPTION

[0023] Certain terms are used in the following description and claims that refer to specific components. As one skilled in the art will recognize, electronic device manufacturers may refer to a component by different names. This document does not intend to distinguish between components that differ in name but function the same. In the following description and claims, the terms "include" and "comprising" are used in an open-ended manner and should be interpreted as "including, but not limited to..." In addition, the term "connected" is intended to mean either an indirect or direct electrical connection. Thus, if one device is connected to another device, that connection may be through a direct electrical connection, or an indirect electrical connection through other devices and connections.

[0024] Figure 11 is a diagram showing a WLAN system supporting a proposed frequency hopping scheme for co-channel interference avoidance according to an embodiment of the present invention. The WLAN system 100 may include a plurality of Wi-Fi devices 102, 104, 112, 114, 116, 118, 120. For example, the Wi-Fi devices 102 and 104 may be access points (labeled as "AP1" and "AP2"), and the Wi-Fi devices 112, 114, 116, 118, 120 may be non-access point working terminals (labeled as "STA1", "STA2", "STA3", "STA4", and "STA5"). For example but not limited to, the Wi-Fi devices 102, 104, 112, 114, 116, 118, 120 may comply with the IEEE 802.11ax (Wi-Fi 6) standard, the IEEE 802.11be (Wi-Fi 7) standard, the IEEE 802.11bn (Wi-Fi 8) standard, or a subsequent (next generation) Wi-Fi standard. Non-access point working terminals (STA1, STA2, STA3, STA4) are associated with an access point (AP1). Non-access point working terminals (STA5) are associated with another access point (AP2). Specifically, the access point (AP1) and the non-access point working terminals (STA1, STA2, STA3, STA4) operate in the same basic service set (BSS) (labeled as "BSS1"), and the access point (AP2) and the non-access point working terminal (STA5) operate in the same BSS (labeled as "BSS2"), wherein the non-access point working terminal (STA5) is a hidden node to the access point (AP1). In this embodiment, the access point (AP1) and the non-access point working terminals (STA1, STA2, STA3, STA4) may support the proposed frequency hopping scheme for avoiding co-channel interference. It should be noted that Figure 1 The topology of the WLAN system 100 shown in FIG. 1 is for illustration purposes only and is not meant to limit the present invention. In practice, the proposed frequency hopping scheme can be adopted by any combination of Wi-Fi devices. For example, the proposed frequency hopping scheme can be used by an access point and N associated non-access point working terminals (N≥1) in the same BSS for co-channel interference avoidance.

[0025] In certain embodiments of the present invention, the access points (AP1, AP2) may be included in the same multiple access point (MAP) system. In a MAP system, several access points form a coordination group. These access points in the same MAP system can provide services to associated client devices at the same time. Specifically, the access points of the same MAP system can share transmission resources, such as transmission opportunities (TXOPs) and target wake-up time (TWT) service periods (SPs). For example, the access points of the same MAP system can perform joint transmission (JT). Specifically, JT is a technology that utilizes the spatial domain and involves non-co-located access points jointly transmitting / receiving data to / from multiple non-access point working terminals. The proposed frequency hopping scheme can also be adopted by any combination of multiple access points in the same MAP system.

[0026] The proposed frequency hopping scheme may be an implicit frequency hopping scheme, performing implicit channel switching or implicit sub-band switching. Alternatively, the proposed frequency hopping scheme may be an explicit frequency hopping scheme, performing explicit channel switching or explicit sub-band switching. More details on the proposed frequency hopping scheme are provided below and in the attached Figure 1 Start description.

[0027] Figure 2is a timing diagram illustrating a frequency hopping scenario with implicit channel switching according to an embodiment of the present invention. Assume that there is an access point (AP1) and a non-AP working terminal (STA1) in one basic service set (BSS1), and an access point (AP2) and a non-AP working terminal (STA5) in another basic service set (BSS2). According to the BSS color, the physical layer protocol data unit (PPDU) sent from the access point (AP1) and received by its associated non-AP working terminal (STA1) is regarded as a MyBSS PPDU, while the PPDU sent from the access point (AP2) and received by the access point (AP1) and the non-AP working terminal (STA1) is regarded as an overlapping BSS (OBSS) PPDU. In this embodiment, implicit channel switching is determined by the information of the OBSS PPDU, and the rules are pre-negotiated. That is, before two Wi-Fi devices (e.g., an access point (AP1) and a non-AP working terminal (STA1) operating in the same BSS1 (MyBSS)) receive a co-channel interference signal (e.g., an OBSS PPDU), one or more parameters are pre-negotiated between the access point (AP1) and the non-AP working terminal (STA1). For example, the pre-negotiated parameters may include a channel switching start time and an end time (which may be related to the OBSS PPDU start time), BSS color, bandwidth, uplink / downlink (UL / DL), legacy length (L-Length), PPDU type, etc., in the HE / EHT format PPDU preamble, media access control (MAC) information in the MAC header, and / or a designated channel. In addition, the pre-negotiation can be based on each BSS or each STA. When the access point (AP1) and the non-AP working terminal (STA1) receive interference signals (e.g., OBSS PPDU) occupying the current operating channel of the access point (AP1) and the current operating channel of the non-AP working terminal (STA1), the access point (AP1) performs a channel switch on its current operating channel, and the non-AP working terminal (STA1) performs a channel switch on its current operating channel. For example, the new operating channel used by the access point (AP1) and the non-AP working terminal (STA1) may be a clean channel without OBSS interference.

[0028] like Figure 2 As shown, both the access point (AP1) and the non-AP working terminal (STA1) support 160MHz bandwidth (BW) and operate on the CH15 160MHz channel before receiving the OBSS PPDU sent by another access point (AP2). Therefore, the current operating channel of the access point (AP1) is the CH15 160MHz channel, and the current operating channel of the non-AP working terminal (STA1) is also the CH15 160MHz channel.

[0029] The access point (AP2) sends an OBSS PPDU occupying the current operating channel (CH15 160MHz channel) of the access point (AP1) and the current operating channel (CH15 160MHz channel) of the non-AP working terminal (STA2). When the non-AP working terminal (STA1) receives the OBSS PPDU carrying the pre-negotiated parameters, it will perform a channel switch to switch to a designated channel (e.g., CH79 160MHz channel) at a channel switch start time (which may depend on the OBSS PPDU preamble time), and perform another channel switch to switch back to the original operating channel (e.g., CH15 160MHz channel) at another channel switch start time (which may depend on the OBSS PPDU end time and the expected OBSS block acknowledgement (BA) time). Similarly, when the access point (AP1) receives the same OBSS PPDU carrying the pre-negotiated parameters, it knows that the non-AP working terminal (STA1) will switch to the designated channel (e.g., CH79 160MHz channel), and will perform a channel switch at a channel switch start time (which may depend on the OBSSPPDU preamble time) to switch to the designated channel (e.g., CH79 160MHz channel), and perform another channel switch at another channel switch start time (which may depend on the OBSS PPDU end time and the expected OBSS BA time) to switch back to the original operating channel (e.g., CH15 160MHz channel).

[0030] After the access point (AP1) and the non-AP working terminal (STA1) perform channel switching to a new operating channel (eg, CH79 160 MHz channel), a frame exchange sequence (FES) may be initiated for uplink / downlink (UL / DL) traffic. Figure 3 is a timing diagram illustrating a frequency hopping scenario with implicit channel switching and downlink (DL) FES according to an embodiment of the present invention. After the channel switching is completed, the access point (AP1) operates on the new operating channel (e.g., CH79 160MHz channel) and sends a request to send (RTS) frame to the non-AP working terminal (STA1) also operating on the new operating channel (e.g., CH79 160MHz channel). In response to the RTS frame from the access point (AP1), the non-AP working terminal (STA1) replies with a clear to send (CTS) frame. After receiving the CTS frame, the access point (AP1) sends a single user (SU) PPDU to the non-AP working terminal (STA1). After receiving the SU PPDU, the non-AP working terminal (STA1) replies with a block acknowledgment (BA) frame.

[0031] When performing implicit channel switching, the new operating channel allocated to the access point and the associated non-AP working terminal is not included in the original operating channel of the access point. In certain embodiments of the present invention, the proposed frequency hopping scheme may be replaced by implicit sub-band switching. When performing implicit sub-band switching, the new operating channel allocated to the associated non-AP working terminal is a sub-band (also called a sub-channel) included in the original operating channel of the access point, and the access point does not need to change its currently used operating channel. For example, the sub-band may be a clean sub-band without OBSS interference.

[0032] Figure 4 This is a timing diagram illustrating a frequency hopping scenario with implicit sub-band switching according to an embodiment of the present invention. Assume that there is an access point (AP1) and a non-AP working terminal (STA1) in one basic service set (BSS1), and an access point (AP2) and a non-AP working terminal (STA5) in another basic service set (BSS2). According to the BSS color, the physical layer protocol data unit (PPDU) sent from the access point (AP1) and received by its associated non-AP working terminal (STA1) is regarded as a MyBSS PPDU, and the PPDU sent from the access point (AP2) and received by the access point (AP1) and the non-AP working terminal (STA1) is regarded as an OBSS PPDU. Like implicit channel switching, implicit sub-band switching is also determined by the information of the OBSS PPDU, and the rules are pre-negotiated. That is, before two Wi-Fi devices (e.g., an access point (AP1) and a non-AP working terminal (STA1) operating in the same BSS1 (MyBSS)) receive a co-channel interference signal (e.g., an OBSS PPDU), one or more parameters are pre-negotiated by the access point (AP1) and the non-AP working terminal (STA1). For example, the pre-negotiated parameters may include a channel switching start time and an end time (which may be related to the OBSS PPDU start time), BSS color, bandwidth, UL / DL, L-Length, PPDU type, etc., in the HE / EHT format PPDU preamble, MAC information in the MAC header, and / or a designated channel. In addition, the pre-negotiation may be based on each BSS or each STA. When the access point (AP1) and the non-AP working terminal (STA1) receive an interference signal (e.g., an OBSS PPDU) that occupies a portion of the current operating channel of the access point (AP1) and the current operating channel of the non-AP working terminal (STA1), the non-AP working terminal (STA1) performs a sub-band switching on its current operating channel.

[0033] like Figure 4As shown, before receiving the OBSS PPDU sent from another access point (AP2), the access point (AP1) supports 320MHz bandwidth and operates on an operating channel (the operating channel consists of a 160MHz main channel and a 160MHz secondary channel); the non-AP working terminal (STA1) supports 160MHz bandwidth and operates on the 160MHz main channel before receiving the OBSS PPDU sent from another access point (AP2). Therefore, the current operating channel of the access point (AP1) is a 320MHz channel, and the current operating channel of the non-AP working terminal (STA1) is a partial operating channel (e.g., 160MHz main channel) included in the current operating channel of the access point (AP1).

[0034] The access point (AP2) sends an OBSS PPDU that occupies a portion of the current operating channel (e.g., 160 MHz primary channel) of the access point (AP1) and also occupies the current operating channel (e.g., 160 MHz primary channel) of the non-AP working terminal (STA2). When the non-AP working terminal (STA1) receives the OBSS PPDU carrying the pre-negotiated parameters, it will perform a sub-band switch to switch to a designated channel (e.g., 160 MHz secondary channel) at a sub-band switch start time (which may depend on the OBSS PPDU preamble time), and perform another sub-band switch to switch back to the original operating channel (e.g., 160 MHz primary channel) at another sub-band switch start time (which may depend on the OBSS PPDU end time and the expected OBSS BA time). Since the access point (AP1) operates on the 320 BW operating channel including the designated channel (e.g., 160 MHz secondary channel) to which the non-AP working terminal (STA1) switches, the access point (AP1) continues to operate on the current operating channel. In this embodiment, when the access point (AP1) receives the same OBSS PPDU carrying the pre-negotiated parameters, it knows that the non-AP working terminal (STA1) will switch to the designated channel (e.g., 160 MHz sub-channel), and if it has only one PD circuit, it may need to change its packet detection (PD) capability to the designated channel (e.g., 160 MHz sub-channel). Figure 4 As shown, after the OBSS PPDU (OBSS PPDU carrying pre-negotiated parameters) begins, the access point (AP1) switches its PD capability to the 160 MHz secondary channel, and switches its PD capability back to the 160 MHz primary channel after the OBSS PPDU ends.

[0035] After the non-AP operating terminal (STA1) performs sub-band switching to switch to a new operating channel (eg, 160 MHz sub-channel), a front end split (FES) may be initiated for UL / DL traffic. Figure 5 is a timing diagram illustrating a frequency hopping scenario with implicit sub-band switching and DL FES according to an embodiment of the present invention. The access point (AP1) operates on the BW320 operating channel and may change its PD capability to the 160 MHz secondary channel. Therefore, the access point (AP1) sends an RTS frame on the 160 MHz secondary channel. In response to the RTS frame from the access point (AP1), the non-AP working terminal (STA1) replies with a CTS frame on the 160 MHz secondary channel. After receiving the CTS frame, the access point (AP1) sends a SU PPDU on the 160 MHz secondary channel. After receiving the SUPPDU, the non-AP working terminal (STA1) replies with a BA frame on the 160 MHz secondary channel.

[0036] Figure 6 1 is a timing diagram illustrating a frequency hopping scenario with implicit sub-band switching and uplink spectrum efficiency (UL FES) according to an embodiment of the present invention. Assume that there is an access point (AP1) and four non-AP working terminals (STA1, STA2, STA3, STA4) in one basic service set (BSS1), and there is an access point (AP2) and one non-AP working terminal (STA5) in another basic service set (BSS2). According to the BSS color coding, the physical layer protocol data unit (PPDU) sent from the access point (AP1) and received by its associated non-AP working terminals (STA1, STA2, STA3, STA4) is regarded as MyBSSPPDU, while the PPDU sent from the access point (AP2) and received by the access point (AP1) and the non-AP working terminals (STA1, STA2, STA3, STA4) is regarded as OBSS PPDU. In this embodiment, the access point (AP2) sends an OBSS PPDU that occupies a portion of the operating channel (e.g., the 160 MHz main channel), which is included in the current operating channel of the access point (AP1) and also occupies the current operating channel (e.g., 160 MHz main channel) of the non-AP working terminals (STA1, STA2, STA3, STA4). st 80MHz channel within the 160MHz main channel).

[0037] When the non-AP working terminal (STA1) receives the OBSS PPDU carrying the pre-negotiated parameters, it will perform sub-band switching and switch to the specified channel (for example, 3 rd 80 MHz channel included in the 160 MHz sub-channel) at a sub-channel switch start time (which may depend on the OBSS PPDU preamble time), and perform another sub-band switch at another sub-band switch start time (which may depend on the OBSS PPDU end time and the expected OBSS BA time), switching back to the original operating channel (e.g., 1st 80MHz channel is included in the 160MHz sub-channel). When the non-AP working terminal (STA2) receives the OBSS PPDU carrying the pre-negotiated parameters, it will perform sub-band switching and switch to the specified channel (for example, 3 rd 80 MHz channel included in the 160 MHz sub-channel) at a sub-channel switch start time (which may depend on the OBSS PPDU preamble time), and perform another sub-band switch at another sub-band switch start time (which may depend on the OBSS PPDU end time and the expected OBSS BA time), switching back to the original operating channel (e.g., 1 st 80MHz channel is included in the 160MHz main channel). When the non-AP working terminal (STA4) receives the OBSS PPDU carrying the pre-negotiated parameters, it will perform sub-band switching and switch to the specified channel (for example, 4 th 80 MHz channel included in the 160 MHz sub-channel) at a sub-channel switch start time (which may depend on the OBSS PPDU preamble time), and perform another sub-band switch at another sub-band switch start time (which may depend on the OBSS PPDU end time and the expected OBSS BA time), switching back to the original operating channel (e.g., 1 st The 80MHz channel is included in the 160MHz main channel).

[0038] The access point (AP1) operates on the BW320 operating channel and may change its PD capability to the 160 MHz secondary channel after receiving the OBSS PPDU. The access point (AP1) sends a multi-user request to send (MU-RTS) frame on the 160 MHz secondary channel. In response to the MU-RTS frame from the access point (AP1), each non-AP working terminal (STA1, STA2, STA3, STA4) switches to the 160 MHz secondary channel on its operating channel (e.g., 3 rd 80MHz channel or 4 th 80MHz channel included in the 160MHz sub-channel) replies with a CTS frame. After receiving the CTS frame, the access point (AP1) sends a trigger frame on the 160MHz sub-channel. After receiving the trigger frame, each non-AP working terminal (STA1, STA2, STA3, STA4) on its operating channel (for example, 3 rd 80MHz channel or 4 th80MHz channel included in the 160MHz sub-channel) sends a trigger-based (TB) PPDU. After receiving TB PPDUs from non-AP active terminals (STA1, STA2, STA3, STA4), the access point (AP1) replies with an orthogonal frequency division multiple access (OFDMA) BA frame or a multi-active terminal (M-STA) BA frame.

[0039] Implicit channel / sub-band switching is performed without explicitly sending notification frames or control frames from the access point to its associated non-AP working terminals. In certain embodiments of the present invention, the proposed frequency hopping scheme may adopt explicit channel / sub-band switching to avoid co-channel interference. Specifically, if the signal-to-noise ratio (SNR) of a receiver of a non-AP working terminal operating on an operating channel occupied by co-channel interference is still high enough to receive the notification frame, the explicit channel / sub-band switching method may be adopted.

[0040] Figure 7 is a timing diagram illustrating a frequency hopping scenario with explicit channel switching and downlink forward error correction (DL FES) according to an embodiment of the present invention. Assume that there is an access point (AP1) and a non-AP working terminal (STA1) in one basic service set (BSS1), and there is an access point (AP2) and a non-AP working terminal (STA5) in another basic service set (BSS2). According to BSS coloring, the physical layer protocol data unit (PPDU) sent from the access point (AP1) and received by its associated non-AP working terminal (STA1) is regarded as a MyBSS PPDU, and the PPDU sent from the access point (AP2) and received by the access point (AP1) and the non-AP working terminal (STA1) is regarded as an overlapping BSS (OBSS) PPDU. As Figure 7 As shown, both the access point (AP1) and the non-AP working terminal (STA1) support 160MHz bandwidth (BW) and operate on the CH15 160MHz channel before receiving the OBSS PPDU sent from another access point (AP2). Therefore, the current operating channel of the access point (AP1) is the CH15 160MHz channel, and the current operating channel of the non-AP working terminal (STA1) is also the CH15 160MHz channel.

[0041] The access point (AP2) sends an OBSS PPDU occupying the current operating channel (CH15 160MHz channel) of the access point (AP1) and the non-AP working terminal (STA2). When the access point (AP1) receives the OBSS PPDU, it will send a notification frame (e.g., RTS frame) to the non-AP working terminal (STA1), and will perform a channel switch to switch to the designated channel (e.g., CH79 160MHz channel) at a channel switch start time, and perform another channel switch to switch back to the original operating channel (e.g., CH15 160MHz channel) at another channel switch start time. In response to the notification frame (e.g., RTS frame) sent from the access point (AP1), the non-AP working terminal (STA1) will perform a channel switch to switch to the designated channel (e.g., CH79 160MHz channel), and perform another channel switch to switch back to the original operating channel (e.g., CH15 160MHz channel) at another channel switch start time.

[0042] After the access point (AP1) and the non-AP working terminal (STA1) perform channel switching to switch to a new operating channel (e.g., CH79 160MHz channel), forward error correction (FES) can be enabled for uplink / downlink (UL / DL) traffic. Figure 7 As shown, the non-AP working terminal (STA1) operates on a new operating channel (e.g., CH79 160MHz channel) and sends a CTS frame to the access point (AP1). After receiving the CTS frame, the access point (AP1) sends a single-user PPDU (SU PPDU) to the non-AP working terminal (STA1). After receiving the SU PPDU, the non-AP working terminal (STA1) responds with a BA frame.

[0043] In some embodiments of the present invention, multiple access points (especially sharing APs and shared APs) in the same multi-AP system may adopt the same explicit channel switching method to avoid co-channel interference. Figure 8 is a timing diagram showing a frequency hopping scenario with explicit channel switching and joint transmission according to an embodiment of the present invention. Assume that access point (AP1) and access point (AP2) are in the same multi-AP system, where access point (AP1) may be a shared AP that shares its resources (e.g., transmission opportunity TXOP) with other access points in the same multi-AP system, and access point (AP2) may be a shared AP that participates in resource sharing provided by the sharing AP. Figure 8As shown in the figure, both the access point (AP1) and the non-AP working terminal (STA1) support 160MHz bandwidth and operate on the CH15 160MHz channel before receiving the same channel interference signal. Therefore, the current operating channel of the shared AP (AP1) is the CH15 160MHz channel, and the current operating channel of the shared AP (AP2) is also the CH15 160MHz channel.

[0044] When the sharing AP (AP1) receives the same channel interference signal, it will send a notification frame (e.g., a multi-AP trigger frame) to the shared AP (AP2), and will perform a channel switch to switch to a designated channel (e.g., CH79 160MHz channel) at a channel switch start time, and perform another channel switch to switch back to the original operating channel (e.g., CH15 160MHz channel) at another channel switch start time. In response to the notification frame (e.g., multi-AP trigger frame) sent from the sharing AP (AP1), the shared AP (AP2) will perform a channel switch to switch to the same designated channel (e.g., CH79 160MHz channel), and perform another channel switch to switch back to the original operating channel (e.g., CH15 160MHz channel) at another channel switch start time. In addition, after the sharing AP (AP1) and the shared AP (AP2) perform a channel switch to switch to a new operating channel (e.g., CH79 160MHz channel), joint transmission can be initiated on the new operating channel (e.g., CH79 160MHz channel).

[0045] When an explicit channel switch is performed, the new operating channel assigned to the access point and the associated non-AP working terminal is not included in the original operating channel of the access point. In some embodiments of the present invention, the proposed frequency hopping scheme may be changed to adopt an explicit sub-band switch. When an explicit sub-band switch is performed, the new operating channel assigned to the associated non-AP working terminal is included in the original operating channel of the access point, and the access point does not need to change its currently used operating channel.

[0046] Fig. 9is a timing diagram illustrating a frequency hopping scenario with explicit sub-band switching and downlink spectrum efficiency (DL FES) according to an embodiment of the present invention. Assume that there is an access point (AP1) and two non-AP working terminals (STA1, STA2) in one basic service set (BSS1), and there is an access point (AP2) and a non-AP working terminal (STA5) in another basic service set (BSS2). According to the BSS color coding, the physical layer protocol data unit (PPDU) sent from the access point (AP1) and received by its associated non-AP working terminals (STA1, STA2) is regarded as a MyBSS PPDU, while the PPDU sent from the access point (AP2) and received by the access point (AP1) and the non-AP working terminals (STA1, STA2) is regarded as an overlapping BSS (OBSS) PPDU. Like explicit channel switching, explicit sub-band switching is initiated by a notification frame (e.g., a sub-band operation notification frame). As shown in FIG. Fig. 9 As shown, before receiving the OBSS PPDU sent from another access point (AP2), the access point (AP1) supports a 320MHz bandwidth (BW) and operates on an operating channel (the operating channel consists of a 160MHz main channel and a 160MHz secondary channel); each non-AP working terminal (STA1 and STA2) supports a 160MHz bandwidth and operates on the 160MHz main channel before receiving the OBSS PPDU sent from another access point (AP2). Therefore, the current operating channel of the access point (AP1) is a 320MHz channel, and the current operating channel of each non-AP working terminal (STA1, STA2) is a partial operating channel (e.g., a 160MHz main channel) included in the current operating channel of the access point (AP1).

[0047] The access point (AP2) sends an OBSS PPDU occupying a portion of the operating channel (e.g., a 160 MHz main channel) that is included in the current operating channel of the access point (AP1) and also occupies the current operating channel (e.g., a 160 MHz main channel) of each non-AP working terminal (STA1, STA2). When the access point (AP1) receives the OBSS PPDU, it sends a sub-band operation notification frame (e.g., a multi-user request to send frame (MU-RTS) frame) to the non-AP working terminals (STA1, STA2).

[0048] In this embodiment, the sub-band operation notification frame (e.g., MU-RTS frame) may indicate that the non-AP working terminal (STA1) does not need to perform sub-band switching, while the non-AP working terminal (STA2) needs to perform sub-band switching. Therefore, in response to the sub-band operation notification frame (e.g., MU-RTS frame) sent from the access point (AP1), the non-AP working terminal (STA1) maintains operation on the current operating channel (e.g., 160 MHz main channel), while the other non-AP working terminal (STA2) will perform sub-band switching at a sub-channel switching start time, switch to the designated channel (e.g., 160 MHz secondary channel), and perform another sub-band switching at another sub-band switching start time, switching back to the original operating channel (e.g., 160 MHz main channel).

[0049] After the non-AP working terminal (STA2) performs a sub-band switch to a new operating channel (e.g., a 160 MHz secondary channel), a spectrum efficiency (FES) can be initiated for uplink / downlink traffic. The access point (AP1) operates on the BW320 operating channel and receives an acknowledgment frame (CTS frame) from the non-AP working terminal (STA2) on the 160 MHz secondary channel. Next, the access point (AP1) sends a multi-user PPDU on the 320 MHz operating channel. After receiving the multi-user PPDU, the non-AP working terminal (STA1) responds with an orthogonal frequency division multiple access block acknowledgment frame (OFDMA BA frame) on the 160 MHz primary channel. After receiving the multi-user PPDU, the non-AP working terminal (STA2) responds with an OFDMA BA frame on the 160 MHz secondary channel.

[0050] about Fig. 9 In the illustrated embodiment, the response frame (e.g., CTS frame) generated in response to the sub-band operation notification frame (e.g., MU-RTS frame) is sent only on the new operation channel (e.g., 160 MHz secondary channel). Specifically, with respect to the sub-band operation notification frame (e.g., MU-RTS frame), the non-AP working terminal (STA2) instructed to perform sub-band switching will respond to a CTS frame only on the 160 MHz secondary channel, while the non-AP working terminal instructed to stay on the 160 MHz primary channel will not respond to the CTS frame on the 160 MHz primary channel because its network allocation vector (NAV) is not necessarily a zero value at this moment.

[0051] In some embodiments of the present invention, the sub-band operation notification frame sent from the access point may instruct each non-AP working terminal that is interfered by the same channel interference signal (e.g., OBSS PPDU) to perform sub-band switching to avoid the same channel interference (e.g., only secondary channel sub-band operation during the main channel interference period). Regarding the only secondary channel sub-band operation during the main channel interference period, there are two types of FES. One is implicit sub-band switching FES, such as Figure 4 The other is to explicitly switch the sub-band FES, such as Fig.10 shown.

[0052] In certain embodiments of the present invention, an access point (AP) may provide negotiation suggestions of different topologies to its associated non-AP working terminal (STA). Specifically, due to various situations determined based on the capabilities of the associated non-AP STA, and only the AP has a global view, the AP may provide negotiation suggestions to its associated non-AP STA to avoid unnecessary switching actions of the non-AP STA. In this way, the Wi-Fi system can achieve better throughput performance and delay performance. For example, when the proposed frequency hopping scheme adopts implicit / explicit channel switching, an AP (e.g., AP1) provides a negotiation suggestion to a non-AP STA (e.g., one of STA1, STA2, STA3, and STA4) to suggest the action of channel switching performed on the current operating channel of the non-AP STA. For another example, when the proposed frequency hopping scheme adopts implicit / explicit sub-band switching, an AP (e.g., AP1) provides a negotiation suggestion to a non-AP STA (e.g., one of STA1, STA2, STA3, and STA4) to suggest the action of sub-band switching performed on the current operating channel of the non-AP STA. Taking a BW320 AP (e.g., AP1) as an example, the negotiation proposal provided by the AP to three BW80 non-AP STAs (e.g., STA1, STA2, and STA3) may include switching to the second 80 MHz channel for STA1, switching to the third 80 MHz channel for STA2, and switching to the fourth 80 MHz channel for STA3. However, this is only for illustrative purposes and is not meant to be limiting of the present invention.

[0053] In certain embodiments of the present invention, when co-channel interference occurs and affects an AP (e.g., AP1) and its associated non-AP STAs (e.g., STA1, STA2, STA3, STA4), the AP may check the status of the current operating channel of each non-AP STA to determine its action (e.g., FES action). For example, if the signal-to-noise ratio of a receiver of a non-AP STA operating on an operating channel occupied by the co-channel interference is still high enough for uplink / downlink frame exchange, the non-AP STA may remain on the current operating channel without performing a sub-band switch. For another example, if the signal-to-noise ratio of a receiver of a non-AP STA operating on an operating channel occupied by the co-channel interference is not high enough for uplink / downlink frame exchange, the non-AP STA may perform a sub-band switch to switch to a clean channel for uplink / downlink frame exchange.

[0054] Fig.11 1 is a flowchart of a dynamic selection mechanism of an AP according to an embodiment of the present invention. In step S1102, an AP (e.g., AP1) receives an OBSS PPDU and identifies the OBSS PPDU as a co-channel interference signal because the OBSS PPDU occupies at least a portion (i.e., part or all) of the current operating channel of the AP (e.g., AP1) and also occupies the current operating channel of at least one non-AP STA (e.g., STA1, STA2, STA3, and / or STA4) associated with the AP (e.g., AP1). The AP (e.g., AP1) may also check the information of the OBSS PPDU to determine whether at least one non-AP STA (e.g., STA1, STA2, STA3, and / or STA4) associated with the AP (e.g., AP1) will perform implicit sub-band switching. Alternatively, the AP (e.g., AP1) may send a notification frame to explicitly control whether at least one non-AP STA (e.g., STA1, STA2, STA3, and / or STA4) associated with the AP (e.g., AP1) should stay on its current operating channel or switch to a new operating channel.

[0055] In step S1104, the AP (e.g., AP1) checks the status of the current operating channel of each at least one non-AP STA (e.g., STA1, STA2, STA3 and / or STA4) associated with the AP (e.g., AP1). In step S1106, the AP (e.g., AP1) determines whether the secondary channel sub-band operation is better than the spatial multiplexing sub-band operation during the main channel interference. If it is determined that the secondary channel sub-band operation is better than the spatial multiplexing sub-band operation during the main channel interference, the AP (e.g., AP1) may take action (e.g., FES action) to perform the secondary channel sub-band operation during the main channel interference (step S1108). If it is determined that the secondary channel sub-band operation is not better than the spatial multiplexing sub-band operation during the main channel interference, the AP (e.g., AP1) may take action (e.g., FES action) to perform the spatial multiplexing sub-band operation (step S1110).

[0056] For example, the actions of the AP (e.g., FES actions) can be divided into 1-1 actions, 2-1 actions, 2-2 actions, 3-1 actions, and 3-2 actions. In the case where there is only one non-AP STA (e.g., STA1) associated with the AP (e.g., AP1), the AP (e.g., AP1) takes 1-1 actions to perform only secondary channel sub-band operations during primary channel interference, such as Fig.12 shown.

[0057] In the case where there are two non-AP STAs (e.g., STA1 and STA2) associated with an AP (e.g., AP1), the non-AP STA (STA1) performs implicit sub-band switching, the non-AP STA (STA2) performs explicit sub-band switching, and the AP (e.g., AP1) takes 2-1 actions to perform secondary channel sub-band operation during primary channel interference, such as Fig.13 shown.

[0058] In the case where there are two non-AP working terminals (e.g., STA1 and STA2) associated with one access point (e.g., AP1), the non-AP working terminal (STA1) remains on its current operating channel, while the non-AP working terminal (STA2) performs implicit sub-band switching, and the access point (e.g., AP1) takes a 2-2 action for spatial multiplexing of sub-band operation, such as Fig.14 shown.

[0059] In the case where there are two non-AP working terminals (e.g., STA1 and STA2) associated with one access point (e.g., AP1), the non-AP working terminal (STA1) performs explicit sub-band switching, and the non-AP working terminal (STA2) performs explicit sub-band switching, the access point (e.g., AP1) takes 3-1 actions for sub-band operation of the secondary channel only during the primary channel interference, such as Fig.15 shown.

[0060] In the case where there are two non-AP working terminals (e.g., STA1 and STA2) associated with one access point (e.g., AP1), the non-AP working terminal (STA1) remains on its current operating channel, while the non-AP working terminal (STA2) performs explicit sub-band switching, and the access point (e.g., AP1) takes 3-2 actions for spatial multiplexing of sub-band operation, such as Fig.16 shown.

[0061] It should be noted that Figure 2-Figure 10 and Figure 12-16 The frequency hopping scenario shown in is for illustrative purposes only and is not meant to limit the present invention. In practice, any wireless LAN system that uses the proposed frequency hopping scheme for co-channel interference avoidance is within the scope of the present invention, wherein the proposed frequency hopping scheme may include implicit channel switching, explicit channel switching, implicit sub-band switching, explicit sub-band switching, or any combination thereof. In addition, the FES operation performed during co-channel interference avoidance may be DL SU, DL / UL OFDMA, or OFDMA of DL / UL MU-MIMO, depending on the actual application requirements.

[0062] For example, if only one non-AP working terminal is associated with an access point, and the single non-AP working terminal performs sub-band switching to switch to a 160 MHz secondary channel, the access point may receive CTS frames on the 160 MHz secondary channel, send SU PPDUs on the 160 MHz secondary channel, and receive BA frames on the 160 MHz secondary channel during a DL FES.

[0063] For example, if only one non-AP working terminal is associated with an access point, and the single non-AP working terminal performs sub-band switching to switch to a 160 MHz secondary channel, the access point may receive a CTS frame on the 160 MHz secondary channel, send a trigger frame on the 160 MHz secondary channel, receive a TB PPDU on the 160 MHz secondary channel, and send a BA frame on the 160 MHz secondary channel during a UL FES.

[0064] For example, if there are two non-AP working terminals associated with an access point, and each non-AP working terminal performs sub-band switching to switch to a 160 MHz secondary channel, the access point may receive CTS frames on the 160 MHz secondary channel, send MU PPDUs on the 160 MHz secondary channel, and receive OFDMA BA frames on the 160 MHz secondary channel during DL FES.

[0065] For example, if there are two non-AP working terminals associated with an access point, one non-AP working terminal remains on a 160 MHz primary channel, and the other non-AP working terminal switches to a 160 MHz secondary channel, the access point may receive CTS frames on the 160 MHz secondary channel, send MU PPDUs on the BW320 operating channel, receive OFDMA BA frames on the 160 MHz primary channel, and receive OFDMA BA frames on the 160 MHz secondary channel during DLFES.

[0066] For example, if there are two non-AP working terminals associated with an access point, and each of the non-AP working terminals performs sub-band switching to switch to a 160 MHz secondary channel, the access point may receive CTS frames on the 160 MHz secondary channel, send trigger frames on the 160 MHz secondary channel, receive TB PPDUs on the 160 MHz secondary channel, and send OFDMA BA frames on the 160 MHz secondary channel during UL FES.

[0067] For example, if there are two non-AP working terminals associated with an access point, one non-AP working terminal remains on a 160 MHz primary channel, and the other non-AP working terminal switches to a 160 MHz secondary channel, the access point may receive CTS frames on the 160 MHz secondary channel, send trigger frames on the BW320 operating channel, receive TB PPDUs on the 160 MHz primary channel, receive TB PPDUs on the 160 MHz secondary channel, and send OFDMA BA frames on the BW320 operating channel during the ULFES.

[0068] For example, if there are multiple non-AP working terminals associated with an access point, and each non-AP working terminal performs sub-band switching to switch to an 80 MHz channel within a 160 MHz secondary channel, the access point may receive a CTS frame on the 80 MHz channel within the 160 MHz secondary channel, send an MU PPDU on the 160 MHz secondary channel, and receive an OFDMA BA frame on the 80 MHz channel within the 160 MHz secondary channel during a DL FES.

[0069] For example, if there are multiple non-AP working terminals associated with one access point, and the non-AP working terminals include a STA that remains on an 80 MHz channel within a 160 MHz primary channel and a STA that switches to an 80 MHz channel within a 160 MHz secondary channel, the access point may receive a CTS frame on the 80 MHz channel within the 160 MHz secondary channel, send an MU PPDU on the BW320 operating channel, receive an OFDMA BA frame on the 80 MHz channel within the 160 MHz primary channel, and receive an OFDMA BA frame on the 80 MHz channel within the 160 MHz secondary channel during a DL FES.

[0070] For example, if there are multiple non-AP working terminals (STAs) associated with an access point (AP), and each non-AP STA performs sub-band switching to switch to an 80 MHz channel within a 160 MHz secondary channel, the AP may receive CTS frames on the 80 MHz channel within the 160 MHz secondary channel, send trigger frames on the 160 MHz secondary channel, receive TB PPDUs on the 80 MHz channel within the 160 MHz secondary channel, and send OFDMA BA frames on the 160 MHz secondary channel during an uplink frame start (UL FES).

[0071] For example, if there are multiple non-AP STAs associated with one AP, and the non-AP STAs include STAs staying on an 80 MHz channel within a primary 160 MHz channel and STAs switched to an 80 MHz channel within a 160 MHz secondary channel, the AP may receive a CTS frame on the 80 MHz channel within the 160 MHz secondary channel, send a trigger frame on the BW320 operating channel, receive a TB PPDU on the 80 MHz channel within the primary 160 MHz channel, receive a TB PPDU on the 80 MHz channel within the 160 MHz secondary channel, and send an OFDMA BA frame on the BW320 operating channel during an uplink frame start (UL FES).

[0072] Furthermore, with respect to implicit / explicit sub-band switching scenarios, an AP may operate on a wide-bandwidth (wide-BW) operating channel consisting of one primary channel and multiple secondary channels.

[0073] In the above embodiments, a Wi-Fi device (e.g., an AP or a non-AP STA) may begin switching back to its original operating channel at the end time of a switching period (e.g., an implicit channel switching period, an explicit channel switching period, an implicit sub-band switching period, or an explicit sub-band switching period). It should be noted that the definition of the switching period may vary, depending on actual design considerations. Therefore, the present invention has no limitation on how to determine the switching period. For example, the switching period may be determined based on the remaining OBSS PPDU period and the expected OBSS BA period. In another example, the switching period may be determined based on the remaining OBSS PPDU period. In another example, the switching period may be determined based on the NAV period from the OBSS RTS frame. However, these are for illustrative purposes only and are not meant to be limitations of the present invention.

[0074] Those skilled in the art will readily appreciate that numerous modifications and variations of the apparatus and methods can be made while retaining the teachings of the invention. Therefore, the above disclosure should be limited within the scope and metes and bounds of the claims.

Claims

1. A wireless local area network (WLAN) system, characterized in that: include: A first Wi-Fi device; and At least one second Wi-Fi device; When the first Wi-Fi device and at least one of the second Wi-Fi devices receive an interference signal and occupy a current operating channel of the first Wi-Fi device and a current operating channel of at least one of the second Wi-Fi devices, the first Wi-Fi device switches the current operating channel of the first Wi-Fi device, and at least one of the second Wi-Fi devices switches the current operating channel of the second Wi-Fi device.

2. The wireless local area network (WLAN) system according to claim 1, characterized in that: The first Wi-Fi device is an access point AP, and at least one of the second Wi-Fi devices includes a non-AP working terminal STA associated with the AP.

3. The wireless local area network (WLAN) system according to claim 2, characterized in that: The first Wi-Fi device and at least one of the second Wi-Fi devices operate in the same basic service set (BSS), and the interference signal is an overlapping BSS (BSS) physical layer protocol data unit (PPDU).

4. The wireless local area network (WLAN) system according to claim 3, characterized in that: The first Wi-Fi device performs a channel switch on the current operating channel of the first Wi-Fi device, and the at least one second Wi-Fi device performs a channel switch on the current operating channel of the second Wi-Fi device in response to at least one parameter included in the OBSS PPDU; and the at least one parameter is pre-negotiated by the first Wi-Fi device and the at least one second Wi-Fi device before the OBSS PPDU is received by the first Wi-Fi device and the at least one second Wi-Fi device.

5. The wireless local area network (WLAN) system according to claim 1, characterized in that: In response to the interference signal, the first Wi-Fi device sends a notification frame to at least one of the second Wi-Fi devices; and in response to the notification frame, at least one of the second Wi-Fi devices switches the channel of the current operating channel of the second Wi-Fi device.

6. The wireless local area network (WLAN) system according to claim 5, characterized in that: The first Wi-Fi device is an access point AP, and at least one of the second Wi-Fi devices includes a non-AP working terminal STA associated with the AP.

7. The wireless local area network (WLAN) system according to claim 6, characterized in that: The first Wi-Fi device provides a negotiation suggestion to at least one of the second Wi-Fi devices to suggest an action of channel switching, wherein the channel switching is performed on the current operating channel of the second Wi-Fi device.

8. The wireless local area network (WLAN) system according to claim 5, characterized in that: The first Wi-Fi device is a shared AP of a multi-AP system, at least one of the second Wi-Fi devices includes a shared AP of the multi-AP system, and the notification frame is a multi-AP trigger frame.

9. The wireless local area network (WLAN) system according to claim 1, characterized in that: The first Wi-Fi device further performs another channel switch to switch back to the original operating channel that the first Wi-Fi device was operating at the time the interference signal was received, and at least one of the second Wi-Fi devices further performs another channel switch to switch back to the original operating channel that at least one of the second Wi-Fi devices was operating at the time the interference signal was received.

10. A wireless local area network (WLAN) system, characterized in that: include: A first Wi-Fi device; and at least one second Wi-Fi device; When the first Wi-Fi device and at least one of the second Wi-Fi devices receive an interference signal that occupies a current operating channel of the first Wi-Fi device and a portion of a current operating channel of at least one of the second Wi-Fi devices, at least one of the second Wi-Fi devices performs sub-channel switching on the current operating channel of the second Wi-Fi device to switch to a new operating channel, where the new operating channel is included in another portion of the operating channels in the current operating channel of the first Wi-Fi device.

11. The wireless local area network (WLAN) system according to claim 10, characterized in that: The first Wi-Fi device is an access point AP, at least one of the second Wi-Fi devices includes a non-AP working terminal STA associated with the AP, the partial operating channel is a main channel, and another partial operating channel is a secondary channel.

12. The wireless local area network (WLAN) system according to claim 11, characterized in that: The first Wi-Fi device and at least one of the second Wi-Fi devices operate in the same basic service set (BSS), and the interference signal is an overlapping BSS (Basic Service Set) BSS physical layer protocol data unit (PPDU).

13. The wireless local area network (WLAN) system according to claim 12, characterized in that: In response to at least one parameter included in the OBSS PPDU, at least one of the second Wi-Fi devices performs a sub-band switch on the current operating channel of the at least one of the second Wi-Fi devices; and the at least one parameter is pre-negotiated by the first Wi-Fi device and the at least one second Wi-Fi device before the OBSS PPDU is received by the first Wi-Fi device and the at least one second Wi-Fi device.

14. The wireless local area network (WLAN) system according to claim 10, characterized in that: In response to the interference signal, the first Wi-Fi device sends a notification frame to at least one second Wi-Fi device; and in response to the notification frame, at least one of the second Wi-Fi devices performs a sub-band switching on the current operating channel of the at least one second Wi-Fi device.

15. The wireless local area network (WLAN) system according to claim 14, characterized in that: The first Wi-Fi device is an access point AP, and at least one of the second Wi-Fi devices includes a non-AP working terminal STA associated with the AP.

16. The wireless local area network (WLAN) system according to claim 15, characterized in that: The first Wi-Fi device provides a negotiation suggestion to at least one of the second Wi-Fi devices to suggest an action of performing a sub-band switching on the current operating frequency channel of the at least one of the second Wi-Fi devices.

17. The wireless local area network (WLAN) system according to claim 15, characterized in that: A response frame generated in response to the notification frame is sent only on the new operating channel.

18. The wireless local area network (WLAN) system according to claim 15, characterized in that: In response to the interference signal, each of the at least one second Wi-Fi devices performs sub-channel switching.

19. The wireless local area network (WLAN) system according to claim 15, characterized in that: In response to the interference signal, the first Wi-Fi device checks a status of the current operating channel of each at least one of the second Wi-Fi devices to determine an action of the first Wi-Fi device.

20. The wireless local area network (WLAN) system according to claim 10, characterized in that: At least one of the second Wi-Fi devices further performs another sub-band switch to switch back to the original operating channel that the at least one of the second Wi-Fi devices was operating at the point in time when the interference signal was received.

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