Continuous waveform (CW) interference detection and mitigation

Abstract

To provide improved methods and systems for CW interference detection and mitigation in a wireless network.SOLUTION: A method comprises: detecting a radio frequency (RF) interference by detecting a time period within a first detection interval during which there is no transmission opportunity, the time period having a duration that meets a duration threshold; and switching, during a second detection interval, from a first bandwidth to a second bandwidth.SELECTED DRAWING: Figure 5A

Description

[Technical field]

[0001] The present disclosure relates to wireless devices, and more particularly, to detection and mitigation of continuous waveform (CW) interference. [Background technology]

[0002] In a scenario where continuous waveform (CW) interference originates from a dedicated short range communication (DSRC) antenna, such CW interference can cause a significant reduction in bandwidth and may even completely halt data transfer in a wireless local area network (WLAN). Such bandwidth reduction and halt in data transfer can be particularly problematic when high speed data transfer is required. To address this issue, dynamic bandwidth switching (DBS) has been introduced to enable WLAN devices to detect interference (e.g., overlapping basic service sets (OBSS), adjacent channel interference, radio frequency (RF) interference, etc.) and switch operating bandwidth to avoid the CW interference. However, current OBSS / interference detection mechanisms are too slow to react and do not always downgrade to the appropriate operating bandwidth in a timely manner (e.g., downgrades occur over multiple detection intervals). This is because under current OBSS / interference detection, the WLAN device measures the percentage of time during a detection interval that the WLAN device (e.g., initiator) and its basic service set (BSS) are either idle (i.e., available for transmission or reception), transmitting and / or receiving. If the percentage of total idle, transmit and / or receive time falls below a threshold percentage, the current OBSS / interference detection indicates that CW interference or other factors limiting the available bandwidth may be present. Thus, if the CW interference does not begin at the beginning of the detection interval, it may not be detected and the bandwidth downgrade occurs later than necessary unless the CW interference covers more than a threshold percentage of the total time during the detection interval that the WLAN may be idle, transmit and / or receive. Furthermore, even if the interference covers more than a threshold percentage of the total time during the detection interval that the WLAN may be idle, transmit and / or receive and the interference was detected earlier, the DBS will only downgrade one bandwidth level per detection interval because there is no information on which frequency in the operating bandwidth the CW interference is located. As a result, if the CW interference is present in a particular sub-band of the operating bandwidth, it may take several detection intervals for the operating bandwidth to be downgraded enough to avoid the CW interference.This delay in detecting and downgrading the operating bandwidth can significantly impact the user experience, especially in scenarios where the detection interval is long (e.g., 500 ms) and it takes multiple detection intervals to downgrade to the appropriate bandwidth. [Brief description of the drawings]

[0003] [Figure 1A] 1 is a block diagram of an exemplary wireless local area network (WLAN) system, according to some embodiments. [Figure 1B] FIG. 1 is a network diagram of a wireless module and a continuous waveform (CW) interferer according to some embodiments. [Figure 2A] FIG. 2 is a timing diagram illustrating detection and mitigation of high speed CW interference in accordance with some embodiments. [Figure 2B] 4 is a timing diagram included for comparison that illustrates conventional interference detection and mitigation in accordance with some embodiments. [Figure 3A] FIG. 13 is a timing diagram illustrating interference detection and mitigation by direct downgrading to unaffected bandwidth in accordance with some embodiments. [Figure 3B] 4 is a timing diagram included for comparison that illustrates conventional interference detection and mitigation in accordance with some embodiments. [Figure 4A] FIG. 1 is a timing diagram illustrating interference detection and mitigation including fast CW interference detection and direct downgrade to unaffected bandwidth in accordance with some embodiments. [Figure 4B] 4 is a timing diagram included for comparison that illustrates conventional interference detection and mitigation in accordance with some embodiments. [Figure 5A] 4 is a flow diagram of a method for performing fast CW interference detection and mitigation in accordance with some embodiments. [Figure 5B] 1 is a flow diagram of a method for performing interference detection and mitigation by direct downgrading to an unaffected bandwidth according to some embodiments. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0004] The following description sets forth numerous specific details, such as examples of specific systems, devices, components, methods, etc., to provide a thorough understanding of various embodiments of interference detection and bandwidth switching.

[0005] The present disclosure relates to methods and systems for continuous waveform (CW) interference detection and mitigation in wireless networks, such as wireless local area networks (WLANs).

[0006] In a scenario where continuous wave (CW) interference comes from a dedicated short range communications (DSRC) antenna, such CW interference can cause a significant reduction in bandwidth and even a complete halt in data transfer in a wireless local area network (WLAN). Such bandwidth reduction and halt in data transfer can be particularly problematic when high speed data transfer is required.

[0007] Carrier Sense Multiple Access / Collision Avoidance (CSMA / CA) is a protocol used by WLAN devices to avoid collisions when transmitting data. CSMA / CA is a medium access control (MAC) protocol used by wireless networks to detect interference independent of dynamic bandwidth switching (DBS) and often stops data transmission before DBS can mitigate the interference. CSMA / CA uses carrier sense to detect if the wireless medium is idle or busy before transmitting data. When a CW interference signal is detected, CSMA / CA causes the WLAN device to stop transmitting until the interference is gone or the bandwidth is downgraded to a sub-band that is not affected by the interference. CSMA / CA detects interference, for example, when CW interference emanating from a DSRC antenna above a threshold (e.g., -62 dBm) is detected and transmission is stopped. This means that the WLAN device does not have a transmission opportunity while such interference persists. A transmission opportunity refers to a channel idle time when the WLAN device is not transmitting, receiving, or being interfered with. To address this issue, DBS was introduced to enable WLAN modules to detect interference (e.g., overlapping basic service sets (OBSS), adjacent channel interference, radio frequency (RF) interference, etc.) and switch the operating bandwidth to avoid CW interference.

[0008] However, current OBSS / interference detection mechanisms are too slow to react and do not always downgrade to the appropriate operating bandwidth in a timely manner. This is because under current OBSS / interference detection, a WLAN device measures the percentage of time during a detection interval that the WLAN device (e.g., initiator) and its basic service set (BSS) are either idle (i.e., available to transmit or receive), transmitting, and / or receiving. If the percentage of total idle time, transmit time, and / or receive time falls below a threshold percentage, current OBSS / interference detection indicates that CW interference or other factors limiting available bandwidth may be present. Thus, if the CW interference does not start at the beginning of a detection interval, it may not be detected and bandwidth downgrade will occur later than necessary unless the CW interference covers more than a threshold percentage of the total time during the detection interval that the WLAN may be idle, transmitting, and / or receiving.

[0009] Using conventional methods, in order to detect interference, the interference must occupy a significant amount of the detection interval (e.g., the total time during which the WLAN device is either idle, transmitting, and / or receiving is less than a threshold percentage) or be present and not detected when transmission stops. Furthermore, even if the interference covers more than a threshold percentage of the total time during the detection interval during which the WLAN may be idle, transmitting, and / or receiving, and the interference is detected earlier, DBS only downgrades one bandwidth level per detection interval because there is no information on which frequency of the operating bandwidth the CW interference is located. As a result, if the CW interference is present in a particular sub-band of the operating bandwidth, it may take several detection intervals for the operating bandwidth to be downgraded enough to avoid the interference. This delay in detecting and downgrading the operating bandwidth can significantly affect the user experience, especially in scenarios where the detection interval is long (e.g., 500 ms) and multiple detection intervals are required to downgrade to the appropriate bandwidth.

[0010] In some examples, under current CW interference detection and mitigation mechanisms, detection of CW interference and downgrading to an appropriate unaffected bandwidth may complete one detection cycle per bandwidth level downgrade (e.g., 80 MHz to 40 MHz, or 40 MHz to 20 MHz, etc.). Downgrading one bandwidth level means downgrading to half the current bandwidth (e.g., 80 MHz to 40 MHz, or 40 MHz to 20 MHz). For example, a WLAN device operating at 80 MHz experiencing CW interference in the 40 MHz sub-band requires at least two detection intervals to downgrade to an appropriate unaffected bandwidth (i.e., 20 MHz).

[0011] Thus, what is needed is a solution that can detect CW interference sooner (even if the total time spent by the WLAN in an idle, transmitting and / or receiving state during the detection interval is longer) and quickly downgrade the operating bandwidth to the required subband (i.e., in fewer detection intervals).To address these and other shortcomings and improve upon the limitations of current CW interference detection and mitigation, this disclosure describes improved methods and systems for CW interference detection and mitigation in wireless networks.

[0012] In at least some embodiments, the present disclosure provides methods for CW interference detection and mitigation in wireless networks that can significantly improve user experience in scenarios where interference is present.

[0013] By using different criteria for CW interference detection and incorporating information about which frequency sub-band of the operating bandwidth the CW interference is located in, the present disclosure provides earlier CW interference detection and faster mitigation (i.e., downgrading to a sub-band not affected by the CW interference). Thus, the present disclosure improves upon the limitations inherent in current CW interference detection and mitigation mechanisms.

[0014] Thus, in at least some embodiments, a method for detection and mitigation of CW interference is disclosed. The method includes detecting RF interference by detecting a period in a first detection interval without a transmission opportunity (a time when the channel is not idle, e.g., a WLAN device is either transmitting, receiving, or CSMA / CA has stopped transmitting / receiving due to CW interference), the period having a duration that meets a duration threshold. The method further includes switching from the first bandwidth to the second bandwidth during a second detection interval. In some embodiments, the first and second detection intervals are consecutive, the first detection interval preceding the second detection interval. In some embodiments, the first bandwidth includes a plurality of subbands, and the second bandwidth is a subset of the plurality of subbands of the first bandwidth. In some embodiments, the RF interference is CW interference.

[0015] In some embodiments, the method may further include determining whether an interference energy level of the second bandwidth meets a threshold interference energy level. The method may further include switching from the first bandwidth to the second bandwidth during the second detection interval in response to determining that the interference energy level of the second bandwidth does not meet the threshold interference energy level. Additional embodiments and implementation variations are described in detail with reference to Figures 1-5.

[0016] The present disclosure includes several advantages, including faster detection of CW interference and faster downgrading of the operating bandwidth to the appropriate unaffected bandwidth. This approach eliminates the delay in triggering to detect CW interference and downgrade the operating bandwidth to the appropriate unaffected bandwidth even if the interference is of short duration and starts at the end of the first detection interval. Furthermore, this approach directly (i.e., within one detection interval) downgrades the operating bandwidth to the appropriate unaffected bandwidth regardless of which sub-band the CW interference is located in, eliminating the stop of data transmission and zero stalls of data transmission (i.e., intervals during which no data is transmitted and / or received). Further advantages will be apparent to those skilled in the art of modern wireless technology. It is noted that the present disclosure is not limited to application in WLAN technology, but may be implemented in any wireless protocol (e.g., Bluetooth, Personal Area Network (PAN), Long Term Evolution (LTE), Near Field Communication (NFC) and / or the like).

[0017] 1A is a block diagram of an exemplary WLAN system, according to some embodiments. In some embodiments, the WLAN system 100 (hereinafter referred to as "system 100") includes a radio module (WLAN module 102), an RF circuit 104, a memory 108, and a processing unit 110. In some embodiments, the WLAN module 102 operates at a particular frequency (e.g., 5 GHz) and an operating bandwidth comprised of multiple sub-bands. For example, the WLAN module may operate at an 80 MHz bandwidth including sub-bands 0 MHz to 20 MHz, 20 MHz to 40 MHz, 40 MHz to 60 MHz, and 60 MHz to 80 MHz. At times, the operating bandwidth of the WLAN module 102 may be reduced to avoid CW interference present in one or more of the sub-bands.

[0018] In some embodiments, the system 100 includes a register 112 in the memory 108. In some embodiments, the system 100 includes interference detection logic 106.

[0019] In some embodiments, the RF circuitry 104 may include an antenna 116. In some embodiments, the antenna 116 transmits and receives radio signals. The antenna 116 may also receive signals that interfere with the operation of the WLAN module 102. In some embodiments, the RF circuitry 104 is coupled to the processing unit 110 and the antenna 116. In some embodiments, the RF circuitry 104 transmits and receives signals in a particular frequency band (i.e., an operating bandwidth). The RF circuitry may operate in a particular frequency band (e.g., 2.4 GHz, 5 GHz, 6 GHz, etc.).

[0020] In some embodiments, the interference detection logic 106 may be logic that, when executed, detects an interfering signal (e.g., CW interference) received by the antenna 116. In some embodiments, the interference detection logic 106 may be firmware embedded in the RF circuitry 104. In some embodiments, the interference detection logic 106 may be stored in the memory 108 as instructions that are executed by the processing unit 110. In some embodiments, such instructions may be written to specific memory locations in a non-volatile memory (e.g., the memory 108) or to hardware registers (e.g., the registers 112).

[0021] In some embodiments, the interference detection logic 106 is implemented as hardware and can detect an interfering signal (e.g., CW interference) received by the antenna 116. In some embodiments, the interference detection logic 106 may be hardware (e.g., part of the RF circuitry 104, coupled to the RF circuitry 104, etc.). In some embodiments, the interference detection logic 106 may be hardware coupled to the processing unit 110.

[0022] In some embodiments, the processing unit 110 may be coupled to the RF circuitry 104. In some embodiments, the processing unit 110 may switch the RF circuitry 104 from operating in a first bandwidth to a second bandwidth. In some embodiments, the processing unit 110 may determine an interference energy level (e.g., stored in a register 112) for a bandwidth (e.g., a sub-band of the operating bandwidth). The processing unit 110 may communicate with the RF circuitry 104. The processing unit 110 may transmit and receive data from the RF circuitry. The processing unit 110 may store data in the memory 108 and retrieve the stored data and other data from the memory 108. The processing unit 110 may also execute instructions retrieved from the memory 108. The processing unit 110 may analyze data received from the memory 108 and / or other components of the WLAN module 102 (e.g., the RF circuitry, the interference detection logic 106, etc.).

[0023] In one example of operation, the WLAN module 102 detects RF interference by detecting a period in the first detection interval where there is no transmission opportunity (i.e., the channel is not idle, e.g., the WLAN device is either transmitting, receiving, or CSMA / CA has stopped transmitting / receiving due to CW interference). In some examples, CSMA / CA stops transmitting when the power level of the CW interference exceeds -62 dBm. The period has a corresponding duration, and the processing unit 110 determines whether the duration of the period meets a duration threshold (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). The RF circuitry 104 is operating at a particular frequency, e.g., 5 GHz, with a bandwidth of, e.g., 80 MHz. The processing unit 110 determines whether each subset of the operating bandwidth (e.g., 0 MHz to 20 MHz, 20 MHz to 40 MHz, 40 MHz to 60 MHz, and 60 MHz to 80 MHz) has an interference energy level (e.g., DSRC signal power) that meets a threshold interference energy level (e.g., DSRC signal power) exceeding −62 dBm. For example, the processing unit 110 can determine that the subband 20 MHz to 40 MHz has an interference energy level (e.g., DSRC signal power) that meets a threshold interference energy level (e.g., DSRC signal power) exceeding −62 dBm. The processing unit 110 can also determine that the interference energy levels of 0 MHz to 20 MHz and 60 MHz to 80 MHz do not meet the threshold interference energy level (e.g., DSRC signal power) exceeding −62 dBm. In response to determining that the interference energy level in subband 0 MHz to 20 MHz does not meet the threshold interference energy level, the processing unit 110 downgrades the operating bandwidth to one or more subbands (e.g., 0 MHz to 20 MHz) that are not affected by interference and resumes transmission. It is important to note that while subband 60 MHz to 80 MHz is not affected by interference, it may be necessary to downgrade to a bandwidth that does not include subband 60 MHz to 80 MHz to avoid interference to subband 20 MHz to 40 MHz.

[0024] 1B is a network diagram of a wireless module and a CW interferer, according to some embodiments. In some embodiments, the network 100B includes a WLAN module 102. In some embodiments, the WLAN module 102 of FIG. 1B may be the same as or similar to the WLAN module 102 of FIG. 1A and may include the same and / or similar components. In some embodiments, the WLAN module 102 may be coupled to a vehicle 190 and may be part of an infotainment system of the vehicle 190. In some embodiments, the network 100B includes a CW interferer 120 having an antenna 126.

[0025] In some embodiments, the CW interference may originate from a DSRC source, such as a DSRC antenna (e.g., antenna 126), or from other sources including a radio frequency identification (RFID) reader, a Wi-Fi device, a Bluetooth device, a radar system, a microwave oven, a satellite communication system, etc. In some embodiments, the CW interference source transmits a CW interference signal 122 via antenna 126. In some embodiments, the CW interference signal 122 may be received by antenna 116 of WLAN module 102 and may interfere with the operation of WLAN module 102, but the CW interference signal 122 may be intended for an on-board unit (OBU) 130 coupled to vehicle 190. In some embodiments, OBU 130 has an antenna 136 for receiving the CW interference signal 122. In some embodiments, the OBU 130 may be part of a toll road and / or bridge system, and the CW interference source 120 is a DSRC device that transmits a CW interference signal 122 to the OBU 130 on the vehicle via the antenna 126 when the vehicle 190 crosses a toll bridge or uses a toll road. The OBU 130 may be used to verify and collect tolls, providing a seamless and efficient toll collection process for drivers and toll booths alike. As described above, a WLAN device (e.g., the WLAN module 102) may experience CW interference (e.g., the CW interference 122) from an interference source such as a toll system that includes a DSRC antenna and an OBU. In some embodiments, such interference causes the WLAN to stop operation (e.g., transmit / receive functions) until the interference subsides (e.g., as the vehicle 190 continues to pass through the toll system) or the WLAN module downgrades to an appropriate sub-band that is not affected by the original operating bandwidth. This may occur when the vehicle 190 approaches the toll booth system and approaches the CW interference source 120.

[0026] FIG. 2A is a timing diagram illustrating high speed CW interference detection and mitigation in accordance with some embodiments.

[0027] In some embodiments, the operating bandwidth 210 of a WLAN device (e.g., WLAN module 102 of FIG. 1A and / or FIG. 1B) is divided into sub-bands. For example, the operating bandwidth 210 is 80 MHz and can be divided into sub-bands 20UU, 20UL, 20LU, and 20LL. In some embodiments, 20LL ranges from 0 MHz to 20 MHz (sub-band 220), 20LU ranges from 20 MHz to 40 MHz (sub-band 240), 20UL ranges from 40 MHz to 60 MHz (sub-band 260), and 20UU ranges from 60 MHz to 80 MHz (sub-band 280). In some embodiments, before interference 212 is detected, the WLAN device operates in an operating bandwidth that includes sub-bands 220, 240, 260, and 280.

[0028] In some embodiments, the detection interval is an interval during which the RF circuitry of the WLAN device scans the sub-bands 220, 240, 260 and 280 to detect interference that may be present. In some embodiments, the RF circuitry of the WLAN device is also transmitting, receiving and / or idle during the detection interval. The processing unit of the WLAN device may initiate the scan by instructing the RF circuitry to switch to a particular frequency band and then wait for a response. In some embodiments, detection of WLAN packets (e.g., via clear channel assessment) and / or interference (e.g., via energy detection) in each sub-band of the operating bandwidth (e.g., 80 MHz) may occur without additional scanning and / or response. The RF circuitry may receive signals from other wireless networks (e.g., interference signals). The RF circuitry may transmit signal information (e.g., interference energy levels) to the processing unit, which analyzes the information to determine the presence, strength and / or duration of the interference. Based on the analysis, the processor may select whether to continue operation on the current bandwidth or downgrade to one or more sub-bands with less interference. The detection interval lasts for a predetermined period of time (eg, 500 ms) during which the RF circuitry and the processing unit cooperate to detect and analyze wireless network signals (eg, interference signals) in the surrounding environment.

[0029] In some embodiments, the detection interval is the interval during which interference detection logic of the WLAN device may be executed to scan the sub-bands 220, 240, 260 and 280 to detect interference that may be present.

[0030] In some embodiments, the WLAN device is operating at a bandwidth of 80 MHz during detection interval 201. Interference 212 begins near the end of detection interval 201. In some embodiments, the interference results in no transmission opportunity for a period of time.

[0031] Even if CSMA / CA stops transmitting / receiving due to CW interference, the channel is no longer idle (i.e., there is no transmission opportunity) when interference is present. When interference is present, CSMA / CA has stopped transmitting / receiving due to CW interference and there is no transmission opportunity (transmission opportunity equals 0) because the interference meets a duration threshold (e.g., lasting more than 20% of the detection interval duration, e.g., 100 ms for a detection interval of 500 ms). In some embodiments, interference 212 is present in a subband 240 of the operating bandwidth. When interference 212 begins, CSMA / CA detects interference 212 and stops transmitting and / or receiving data. This is illustrated by a no transmission opportunity period 214 where the wireless device has zero transmission opportunities (i.e., there is no transmission opportunity due to CSMA / CA detecting interference).

[0032] In some embodiments, a period within a detection interval 201 where there is a transmission opportunity refers to a period during which the channel is idle (i.e., there is no transmission activity, reception activity, or interference). In some embodiments, a period during which the transmission opportunity is equal to 0 correlates with CW interference present on the channel, causing the WLAN device to stop transmitting and receiving via CSMA / CA. In the absence of interference, one continuous period of channel busy time typically does not exceed a threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). A period without a transmission opportunity (i.e., the transmission opportunity is equal to 0) may be referred to as a channel busy time (i.e., when the WLAN device is not transmitting, receiving, or experiencing interference). Note that in normal operation, in the absence of interference, the total time during a detection interval during which the transmission opportunity is equal to 0 may exceed the threshold duration. However, that sum includes shorter non-contiguous periods, each of which is equal to or less than the threshold duration. For example, a WLAN packet transmission may typically be completed in less than 10 milliseconds (e.g., 5-6 milliseconds).

[0033] For example, transmission or reception of a single data frame typically takes less than the threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Furthermore, there is a small interval (interframe space) between data frames during which the wireless device listens for other transmissions or other events on the channel. Thus, even if a WLAN device is transmitting or receiving, for example, 400 ms of data frames with a 500 ms detection interval, those 400 ms may include many shorter periods for transmitting individual data frames that do not meet the duration threshold (e.g., less than 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Furthermore, the periods for transmitting data frames are spaced by the IFS, such that the channel busy time does not exceed 20% of the detection interval duration in any one period (e.g., 100 ms for a 500 ms detection interval, 20 ms for a 100 ms detection interval, etc.) (i.e., the transmission opportunity is not equal to 0 for more than 20% of the detection interval duration at any one time).

[0034] In some embodiments, by using fast CW interference detection, a wireless device (e.g., WLAN module 102 of FIG. 1A or FIG. 1B) detects interference by determining that a period of no transmission opportunity lasts at least a threshold amount of time during the detection interval (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). In this example, interference 212 lasts for at least 20% of the detection interval duration (e.g., 100 ms for a 500 ms detection interval) during detection interval 201, causing the transmission opportunity to equal 0 for the same at least 20% of the detection interval duration, triggering detection of interference and bandwidth downgrade during the next detection interval (detection interval 202). At the start of detection interval 202, the operating bandwidth is downgraded to 40 MHz (i.e., sub-bands 220 and 240). Again, because the no transmission opportunity period lasts for at least 20% of the detection interval duration within detection interval 202, interference 212 is detected, triggering interference detection and bandwidth downgrade during the next detection interval (detection interval 203). At the start of detection interval 203, the operating bandwidth is downgraded to 20 MHz (i.e., subband 220). As CSMA / CA does not detect interference during period 216, data transmission resumes, which again results in a transmission opportunity for the entire duration of detection interval 203. No further bandwidth downgrade is required.

[0035] 2B is included for comparison and is a timing diagram illustrating conventional interference detection and mitigation, in accordance with some embodiments, which outperforms conventional interference detection under the same conditions as FIG.

[0036] For example, during detection interval 201, interference 212 is present, triggering CSMA / CA to stop transmitting and receiving for the WLAN device. However, conventional interference detection uses different criteria to detect interference 212. For conventional interference detection, the condition to trigger a bandwidth downgrade is met when the total channel idle time and data transmission time in the same BSS within the detection interval falls below a predetermined percentage. TxOp is the transmission opportunity or amount of time during which the medium is idle (i.e., there is no transmission, reception or interference on the medium) during a sample duration (e.g., detection interval). For example, if the time that the WLAN device is idle, transmitting and / or receiving is less than a threshold percentage within the sampling period (detection interval), a downgrade is triggered. However, if the sum of idle, transmitting and / or receiving exceeds the threshold percentage, a downgrade is not triggered and interference persists.

[0037] In this example, if it is determined that the WLAN device has been idle, transmitting and / or receiving for less than a threshold percentage during the detection interval 202, then a downgrade is not triggered until the end of the detection interval 202. Although the bandwidth downgrade is eventually initiated at the beginning of the detection interval 203, data transmission is still halted during period 216 because one more downgrade needs to be performed before the appropriate unaffected bandwidth is reached (i.e., 20 MHz, sub-band 220).

[0038] 3A is a timing diagram illustrating interference detection and mitigation by directly downgrading to an unaffected bandwidth, according to some embodiments. In some embodiments, the operating bandwidth 210 of a WLAN device (e.g., WLAN module 102) is divided into sub-bands. For example, the operating bandwidth 210 is 80 MHz and can be divided into sub-bands 20UU, 20UL, 20LU, and 20LL. In some embodiments, 20LL ranges from 0 MHz to 20 MHz (sub-band 220), 20LU ranges from 20 MHz to 40 MHz (sub-band 240), 20UL ranges from 40 MHz to 60 MHz (sub-band 260), and 20UU ranges from 60 MHz to 80 MHz (sub-band 280). In some embodiments, before interference 212 is detected, the WLAN device operates in an 80 MHz operating bandwidth that includes sub-bands 220, 240, 260, and 280.

[0039] In some embodiments, the detection interval is an interval during which the RF circuitry of the WLAN device scans the sub-bands 220, 240, 260 and 280 to detect interference that may be present. In some embodiments, the RF circuitry of the WLAN device is also transmitting, receiving and / or idle during the detection interval. The processing unit of the WLAN device may initiate the scan by instructing the RF circuitry to switch to a particular frequency band and then wait for a response. In some embodiments, detection of WLAN packets (e.g., via clear channel assessment) and / or interference (e.g., via energy detection) in each sub-band of the operating bandwidth (e.g., 80 MHz) may occur without additional scanning and / or response. The RF circuitry may receive signals from other wireless networks (e.g., interference signals). The RF circuitry may transmit signal information (e.g., interference energy levels) to the processing unit, which analyzes the information to determine the presence, strength and / or duration of the interference. Based on the analysis, the processor may select whether to continue operation on the current bandwidth or downgrade to one or more sub-bands with less interference. The detection interval lasts for a predetermined period of time (eg, 500 ms) during which the RF circuitry and the processing unit cooperate to detect and analyze wireless network signals (eg, interference signals) in the surrounding environment.

[0040] In some embodiments, the detection interval is an interval during which the interference detection logic of the WLAN device may be executed to scan the sub-bands 220, 240, 260 and 280 to detect possible interference. In some embodiments, during the detection interval 201, the WLAN device is operating in an 80 MHz bandwidth.

[0041] The interference 212 begins near the beginning of the detection interval 201 and occupies more than a threshold percentage of the detection interval 201 (i.e., the WLAN device has been idle, transmitting and / or receiving for less than the threshold percentage of the detection interval). The interference 212 is present in a subband 240 of the operating bandwidth. When the interference 212 begins, CSMA / CA detects the interference 212 and stops transmitting and / or receiving data. This is indicated by a no transmit opportunity period 214 during which the wireless device's transmit opportunity is equal to zero (i.e., no transmit opportunity exists due to CSMA / CA detecting the interference).

[0042] In some embodiments, by directly downgrading to an unaffected bandwidth, the wireless device determines which frequency subbands have an elevated interference energy level and avoids long-term interference by downgrading to a subband below the subband with the elevated interference energy level. In some embodiments, the WLAN device can determine which frequency subbands have an elevated interference energy level and which subbands do not have an elevated interference energy level. The WLAN device can downgrade to a subband without an elevated interference energy level that is lower than the subband with the elevated interference energy level.

[0043] In this example, interference 212 is detected during detection interval 201 and triggers a bandwidth downgrade during the next detection interval (detection interval 202). The WLAN device determines that subband 240 has an elevated interference energy level by checking a register in which the interference energy level is stored. In some embodiments, the WLAN device can also determine that subband 220 does not have an elevated interference energy level by checking a register in which the interference energy level is stored. At the start of detection interval 202, the WLAN device downgrades the operating bandwidth directly to 20 MHz (i.e., subband 220) since 20 MHz is the next subband below the affected 40 MHz subband and subband 220 is not affected by interference. During period 216, data transmission resumes because CSMA / CA no longer detects interference and therefore a transmission opportunity exists for the entire duration of detection intervals 202 and 203. No further bandwidth downgrade is necessary.

[0044] 3B is a timing diagram included for comparison that illustrates conventional interference detection and mitigation, in accordance with some embodiments. The present disclosure outperforms conventional interference mitigation under the same conditions as FIG. 3A.

[0045] For example, during detection interval 201, interference 212 is present, causing CSMA / CA to trigger the WLAN device to stop transmitting and receiving.

[0046] The interference 212 begins near the beginning of the detection interval 201 and occupies more than a threshold percentage of the detection interval 201 (i.e., the WLAN device has been idle, transmitting and / or receiving for less than a threshold percentage of the detection interval). The interference 212 is present in a subband 240 of the operating bandwidth. When the interference 212 begins, CSMA / CA detects the interference 212 and stops transmitting and / or receiving data. This is illustrated by a no transmission opportunity period 214 during which the wireless device's transmission opportunity is equal to zero (i.e., no transmission opportunity exists due to CSMA / CA detecting the interference). However, even if the interference is detected at the end of the detection interval 201, the downgrade takes significantly longer than the present disclosure because conventional interference mitigation mechanisms only downgrade one bandwidth level per detection interval in which the interference is detected. In some embodiments, downgrading one bandwidth level means downgrading to half the current bandwidth (e.g., from 80 MHz to 40 MHz, or from 40 MHz to 20 MHz).

[0047] In this example, a downgrade is triggered and the detection interval 201 ends, but the bandwidth is only downgraded to the 40 MHz sub-bands (i.e., sub-bands 220 and 240) where the interference is still present (i.e., in sub-band 240). The bandwidth downgrade must be performed again at the beginning of the detection interval 203. Data transmission resumes during period 216, but the resumption of transmission takes longer than the technique used in this disclosure. As shown, the no transmission opportunity period 214 in FIG. 3B is significantly longer than the no transmission opportunity period 214 in FIG. 3A because the conventional mitigation takes time to downgrade to a suitable unaffected bandwidth (e.g., sub-band 220) to avoid the interference 212.

[0048] FIG. 4A is a timing diagram illustrating interference detection and mitigation including fast CW interference detection and direct downgrade to unaffected bandwidth, according to some embodiments. In some embodiments, the operating bandwidth 210 of a WLAN device (e.g., WLAN module 102) is divided into sub-bands. For example, the operating bandwidth 210 is 80 MHz and can be divided into sub-bands 20UU, 20UL, 20LU, and 20LL. In some embodiments, 20LL ranges from 0 MHz to 20 MHz (sub-band 220), 20LU ranges from 20 MHz to 40 MHz (sub-band 240), 20UL ranges from 40 MHz to 60 MHz (sub-band 260), and 20UU ranges from 60 MHz to 80 MHz (sub-band 280). In some embodiments, before interference 212 is detected, the WLAN device operates in an 80 MHz operating bandwidth that includes sub-bands 220, 240, 260, and 280.

[0049] In some embodiments, the detection interval is an interval during which the RF circuitry of the WLAN device scans the sub-bands 220, 240, 260 and 280 to detect interference that may be present. In some embodiments, the RF circuitry of the WLAN device is also transmitting, receiving and / or idle during the detection interval. The processing unit of the WLAN device may initiate the scan by instructing the RF circuitry to switch to a particular frequency band and then wait for a response. In some embodiments, detection of WLAN packets (e.g., via clear channel assessment) and / or interference (e.g., via energy detection) in each sub-band of the operating bandwidth (e.g., 80 MHz) may occur without additional scanning and / or response. The RF circuitry may receive signals from other wireless networks (e.g., interference signals). The RF circuitry may transmit signal information (e.g., interference energy levels) to the processing unit, which analyzes the information to determine the presence, strength and / or duration of the interference. Based on the analysis, the processor may select whether to continue operation on the current bandwidth or downgrade to one or more sub-bands with less interference. The detection interval lasts for a predetermined period of time (eg, 500 ms) during which the RF circuitry and the processing unit cooperate to detect and analyze wireless network signals (eg, interference signals) in the surrounding environment.

[0050] In some embodiments, the detection interval is the interval during which interference detection logic of the WLAN device may be executed to scan the sub-bands 220, 240, 260 and 280 to detect interference that may be present.

[0051] In some embodiments, the WLAN device is operating at a bandwidth of 80 MHz during detection interval 201. Interference 212 begins near the end of detection interval 201. In some embodiments, the interference results in no transmission opportunity for a period of time.

[0052] Even if CSMA / CA stops transmitting / receiving due to CW interference, the channel is not idle (i.e., there is no transmission opportunity) when interference is present. In this case, the transmission opportunity is equal to 0 because CSMA / CA has stopped transmitting / receiving due to CW interference and the interference meets a duration threshold (e.g., lasting more than 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). In some embodiments, interference 212 is present in a subband 240 of the operating bandwidth. When interference 212 begins, CSMA / CA detects interference 212 and stops transmitting and / or receiving data. This is illustrated by a no transmission opportunity period 214 where the wireless device has zero transmission opportunities (i.e., there is no transmission opportunity due to CSMA / CA detecting interference).

[0053] In some embodiments, a period within a detection interval 201 during which there is a transmission opportunity (i.e., there is an opportunity to transmit and / or receive) refers to a period during which the channel is idle (i.e., there is no transmission activity, reception activity, or interference). In some embodiments, a period during which the transmission opportunity is equal to 0 correlates with CW interference present on the channel, causing the WLAN device to stop transmitting and receiving via CSMA / CA. In the absence of interference, one continuous period of channel busy time typically does not exceed the threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Note that in normal operation, in the absence of interference, the total time during which the transmission opportunity is equal to 0 during a detection interval may exceed the threshold duration. However, that sum includes shorter non-contiguous periods, each of which is equal to or less than the threshold duration. For example, a WLAN packet transmission can typically be completed in less than 10 milliseconds (e.g., 5-6 milliseconds).

[0054] For example, transmission or reception of a single data frame typically takes less than the threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Furthermore, there are small intervals (interframe spaces) between data frames during which the wireless device is listening for other transmissions or other events on the channel. Thus, even if a WLAN device is transmitting or receiving, for example, 400 ms of data frames with a 500 ms detection interval, those 400 ms may include many shorter periods for transmitting individual data frames that do not meet the duration threshold (e.g., less than 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Furthermore, the periods for transmitting data frames are spaced by the IFS, such that the channel busy time does not exceed 20% of the detection interval duration (e.g., 100 ms for a 500 ms detection interval) in any one period (i.e., the transmission opportunity is not equal to 0 for more than 20% of the detection interval duration at any one time).

[0055] In some embodiments, by using fast CW interference detection, a wireless device (e.g., WLAN module 102 of FIG. 1A or FIG. 1B) detects interference by determining that a period of no transmission opportunity lasts for at least a threshold amount of time (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval) during a detection interval (e.g., detection interval 201). In this example, interference 212 lasts for at least 20% of the detection interval duration during detection interval 201, causing the transmission opportunity to equal 0 for the same at least 20% of the detection interval duration, triggering detection of interference and bandwidth downgrade during the next detection interval (detection interval 202).

[0056] Further, the WLAN device determines that subband 240 has an elevated interference energy level by checking a register in which the interference energy level is stored. In some embodiments, the WLAN device may also determine that subband 220 does not have an elevated interference energy level by checking a register in which the interference energy level is stored. At the beginning of detection interval 202, the WLAN device directly downgrades the operating bandwidth to 20 MHz (i.e., subband 220) since 20 MHz is the next subband below the affected 40 MHz subband and subband 220 is not affected by interference. During period 216, data transmission resumes because CSMA / CA no longer detects interference and therefore transmission opportunities exist for the entire duration of detection intervals 202 and 203. No further bandwidth downgrade is required. This example employs both fast CW interference detection and direct downgrade to the unaffected bandwidth, resulting in faster detection of interference and faster mitigation (i.e., faster switching to the appropriate unaffected bandwidth).

[0057] 4B is included for comparison and is a timing diagram illustrating conventional interference detection and mitigation, in accordance with some embodiments, which the present disclosure outperforms under the same conditions as FIG.

[0058] For example, during detection interval 201, interference 212 is present, triggering CSMA / CA to stop transmitting and receiving for the WLAN device. However, conventional interference detection uses different criteria to detect interference 212. For conventional interference detection, the condition to trigger a bandwidth downgrade is met when the total channel idle time and data transmission time in the same BSS within the detection interval falls below a predetermined percentage. TxOp is the transmission opportunity or amount of time during which the medium is idle (i.e., there is no transmission, reception or interference on the medium) during a sample duration (e.g., detection interval). For example, if the time that the WLAN device is idle, transmitting and / or receiving is less than a threshold percentage within the sampling period (detection interval), a downgrade is triggered. However, if the sum of idle, transmitting and / or receiving exceeds the threshold percentage, a downgrade is not triggered and interference persists.

[0059] In this example, if it is determined that the WLAN device has been idle, transmitting and / or receiving for less than a threshold percentage of the detection interval 202, then the downgrade is not triggered until the end of the detection interval 202. The bandwidth downgrade finally starts at the beginning of the detection interval 203. At the end of the detection interval 203, the interference is still detected, but it is present in the sub-band 240, since the WLAN device only downgrades one bandwidth level (e.g., to 40 MHz). In some embodiments, downgrading one bandwidth level means downgrading to half the current bandwidth (e.g., from 80 MHz to 40 MHz, or from 40 MHz to 20 MHz). Thus, the interference is again detected at the end of the detection interval 203, and the bandwidth downgrade is again triggered. At the beginning of the detection interval 204, the WLAN device downgrades the operating bandwidth to 20 MHz (i.e., sub-band 220). No further interference is detected, and data transmission resumes for the period 216.

[0060] As shown, the no transmission opportunity period 214 in FIG. 4B is much longer than the no transmission opportunity period 214 in FIG. 4A because conventional interference detection and mitigation takes time to detect the interference 212 and downgrade to an appropriate unaffected bandwidth to avoid the interference 212.

[0061] 5A-5B are flow diagrams of methods for implementing CW interference detection and mitigation, according to various embodiments. Methods 500A-500B may be implemented by processing logic, which may include hardware (e.g., a processing device, circuitry, dedicated logic, programmable logic, microcode, device hardware, integrated circuits, etc.), software (e.g., instructions running or executing on a processing device), or a combination thereof. In some embodiments, methods 500A-500B are implemented by control logic and / or hardware of one of the WLAN modules of FIG. 1A or FIG. 1B. Although shown in a particular sequence or order, unless otherwise noted, the order of processes may be modified. Thus, the illustrated embodiments should be understood as examples only, and the illustrated processes may be implemented in a different order, and some processes may be implemented in parallel. Additionally, in various embodiments, one or more processes may be omitted. Thus, not all processes are required in all embodiments. Other process flows are possible.

[0062] FIG. 5A is a flow diagram of a method for performing fast CW interference detection and mitigation according to some embodiments.

[0063] The method 500A begins at block 502 where processing logic implementing the method detects RF interference by detecting a period within a first detection interval without a transmission opportunity, the period having a duration that meets a duration threshold.

[0064] In some embodiments, a period within the first detection interval during which there is no transmission opportunity refers to a period during which the channel is not idle (i.e., there is either transmission activity, reception activity, or interference). As described below, a period within the detection interval during which there is no transmission opportunity that meets a duration threshold typically correlates to interference rather than transmission and / or reception activity.

[0065] In some embodiments, such periods of no transmission opportunity (i.e., transmission opportunity equals 0) correlate to CW interference present on the channel, causing the WLAN device to cease transmitting and receiving via CSMA / CA. In the absence of interference, one continuous period of channel busy time typically does not exceed the threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Note that in normal operation, in the absence of interference, the total time during a detection interval during which there is no transmission opportunity (i.e., transmission opportunity equals 0) may exceed the threshold duration. However, that sum includes shorter non-contiguous periods that are each less than or equal to the duration threshold and do not meet the duration threshold.

[0066] For example, transmission or reception of a single data frame typically takes less than the threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Furthermore, there are small intervals (IFS) between data frames during which the wireless device is listening for other transmissions or other events on the channel. Thus, even if a WLAN device is transmitting or receiving, for example, 400 ms of data frames with a 500 ms detection interval, those 400 ms may include many shorter periods for transmitting individual data frames that do not meet the duration threshold (e.g., less than 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Furthermore, the periods for transmitting data frames are spaced by the IFS, such that the channel busy time does not exceed 20% of the detection interval duration (e.g., 100 ms for a 500 ms detection interval) in any one period (i.e., the transmission opportunity is not equal to 0 for more than 20% of the detection interval duration at any one time).

[0067] In some embodiments, a controller (e.g., a power-save mode microcontroller in the MAC layer) can record the maximum duration for which there are zero transmission opportunities within a detection interval (e.g., DBS detection interval). The controller (e.g., as a function of DBS) can check the recorded value for each detection event. In some embodiments, CW interference is detected when the duration for which there are zero transmission opportunities exceeds a defined threshold (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval).

[0068] In some embodiments, the RF interference may be CW interference.

[0069] In some embodiments, the duration threshold is configurable. In one example, the duration threshold may be 20% of the detection interval duration, or any other percentage of the detection interval duration, such as 15%, 25% of the detection interval duration, etc. In some embodiments, the duration threshold may be a fixed duration (e.g., 100 ms, 50 ms, 20 ms, etc.).

[0070] At block 504, the processing logic switches from the first bandwidth to the second bandwidth during the second detection interval. In some embodiments, the first bandwidth can include multiple sub-bands and the second bandwidth can include a subset of the multiple sub-bands of the first bandwidth. For example, a WLAN device may be operating in a first bandwidth that is 80 MHz and includes sub-bands 20LL (range 0 MHz to 20 MHz), 20LU (range 20 MHz to 40 MHz), 20UL (range 40 MHz to 60 MHz) and 20UU (range 60 MHz to 80 MHz). The WLAN device can switch to a second bandwidth that is a subset of the sub-bands included in the original operating bandwidth, e.g., 20LU and 20LL (0 MHz to 40 MHz).

[0071] In some embodiments, the first and second detection intervals may be consecutive, with the first detection interval preceding the second detection interval.

[0072] In some embodiments, the processing logic may further determine whether an interference energy level of the second bandwidth meets a threshold interference energy level. In some embodiments, an energy detection (ED) is elevated in the affected frequency subband where the interference is present. In some embodiments, an interference energy level that meets a threshold interference energy level means that the ED is elevated.

[0073] In some embodiments, the interference energy level of the second bandwidth may be a value stored in a register. In some embodiments, when CW interference is detected, the processing logic checks a corresponding PhyEDIndication field in the register to identify where the CW interference is located (i.e., which frequency sub-band) and downgrade to an unaffected bandwidth. For example, the register may include a PhyEDIndication or interference energy level field, where each bit of the field corresponds to a 20 MHz sub-band and operating bandwidth for which the physical layer (PHY) is providing a PhyEDIndication or interference energy level indication. In some embodiments, reading a 1 in this field indicates that the PHY has asserted a PhyEDIndication or that the interference energy level of the corresponding 20 MHz sub-band meets a threshold interference energy level.

[0074] In some embodiments, the processing logic may reference a register (eg, an existing hardware register) to identify where the CW interference is located.

[0075] In some embodiments, the processing logic can determine whether a frequency subband has an elevated interference energy level and which subbands do not have an elevated interference energy level. The processing logic can downgrade operation of the RF circuitry to a subband that does not have an elevated interference energy level that is lower than the subband that has the elevated interference energy level.

[0076] In some embodiments, interference is detected during a detection interval. The processing logic can determine which subbands have an elevated interference energy level by checking a register in which the interference energy level is stored. In some embodiments, the processing logic can also determine which subbands do not have an elevated interference energy level by checking a register in which the interference energy level is stored.

[0077] In response to determining that the interference energy level of the second bandwidth does not meet the threshold interference energy level, the processing unit can switch from the first bandwidth to the second bandwidth during the second detection interval. In some embodiments, the second bandwidth can include multiple subbands (e.g., 20 MHz and 40 MHz). In some embodiments, determining that the interference energy level of the second bandwidth does not meet the threshold interference energy level includes determining that the interference energy level of each subband of the second bandwidth does not meet the threshold interference energy level.

[0078] FIG. 5B is a flow diagram of a method for performing interference detection and mitigation by directly downgrading to an unaffected bandwidth according to some embodiments.

[0079] The method 500B begins at block 512 where processing logic implementing the method detects RF interference in a first bandwidth within a first detection interval. In some embodiments, the first bandwidth is an operating bandwidth of the WLAN device. In some embodiments, the RF interference is CW interference.

[0080] At block 514, the processing logic determines whether the interference energy level of the second bandwidth meets a threshold interference energy level. In some embodiments, the first bandwidth includes a plurality of subbands and the second bandwidth includes a subset of the plurality of subbands of the first bandwidth. For example, a WLAN device may be operating in a first bandwidth that is 80 MHz and includes subbands 20LL (range 0 MHz to 20 MHz), 20LU (range 20 MHz to 40 MHz), 20UL (range 40 MHz to 60 MHz) and 20UU (range 60 MHz to 80 MHz). The WLAN device may switch to a second bandwidth that is a subset of the subbands included in the original operating bandwidth, e.g., 20LU and 20LL (0 MHz to 40 MHz).

[0081] In some embodiments, an energy detection (ED) is raised in the affected frequency subband where interference is present. In some embodiments, an interference energy level that meets a threshold interference energy level means that ED is raised (i.e., interference is present in the subband). In some embodiments, the interference energy level of the second bandwidth is a value stored in a register. In some embodiments, when CW interference is detected, the processing logic checks a corresponding PhyEDIndication field in the register to identify where the CW interference is located (i.e., which frequency subband) and downgrades to an unaffected bandwidth. For example, the register may include a PhyEDIndication or interference energy level field, where each bit of the field corresponds to a 20 MHz subband and operating bandwidth for which the physical layer (PHY) is providing a PhyEDIndication or interference energy level indication. In some embodiments, reading a 1 in this field indicates that the PHY has asserted a PhyEDIndication or that the interference energy level of the corresponding 20 MHz subband meets the threshold interference energy level. In some embodiments, reading a 0 in this field indicates that the PHY did not assert PhyEDIndication or that the interference energy level in its corresponding 20 MHz sub-band does not meet the threshold interference energy level.

[0082] In some embodiments, the processing logic can determine whether a frequency subband has an elevated interference energy level and which subbands do not have an elevated interference energy level. The processing logic can downgrade operation of the RF circuitry to a subband that does not have an elevated interference energy level that is lower than the subband that has the elevated interference energy level.

[0083] In some embodiments, interference is detected during a detection interval. The processing logic can determine which subbands have an elevated interference energy level by checking a register in which the interference energy level is stored. In some embodiments, the processing logic can also determine which subbands do not have an elevated interference energy level by checking a register in which the interference energy level is stored.

[0084] At block 516, the processing logic switches from the first bandwidth to the second bandwidth in response to determining that the interference energy level of the second bandwidth does not meet the threshold interference energy level (i.e., no interference is present in the second bandwidth) during the second detection interval. In some embodiments, the first and second detection intervals are consecutive, with the first detection interval preceding the second detection interval.

[0085] In some embodiments, detecting RF interference in the first bandwidth within a first detection interval includes detecting a period within the first detection interval in which there is no transmission opportunity, the period having a duration that meets a duration threshold. As described below, a period within the detection interval in which there is no transmission opportunity that meets a duration threshold typically correlates to interference rather than transmission and / or reception activity.

[0086] In some embodiments, such periods of no transmission opportunity (i.e., transmission opportunity equals 0) correlate to CW interference present on the channel, causing the WLAN device to stop transmitting and receiving by CSMA / CA. In the absence of interference, one continuous period of channel busy time typically does not exceed a threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). A period of no transmission opportunity (i.e., transmission opportunity equals 0) may be referred to as channel busy time (i.e., when the WLAN device is not transmitting, receiving, or experiencing interference). Note that in normal operation, in the absence of interference, the total time of no transmission opportunity (i.e., transmission opportunity equals 0) during a detection interval may exceed the threshold duration. However, the sum includes shorter non-contiguous periods, each of which is less than or equal to the duration threshold and does not meet the duration threshold.

[0087] For example, transmission or reception of a single data frame typically takes less than the threshold duration (e.g., 20% of the detection interval duration, e.g., 100 ms for a 500 ms detection interval). Furthermore, there are small intervals (IFS) between data frames during which the wireless device is listening for other transmissions or other events on the channel. Thus, even if a WLAN device is transmitting or receiving, for example, 400 ms of data frames with a 500 ms detection interval, those 400 ms may include many shorter periods for transmitting individual data frames that do not meet the duration threshold (e.g., less than 20% of the detection interval duration). Furthermore, the periods for transmitting data frames are spaced by the IFS, such that the channel busy time does not exceed 20% of the detection interval duration in any one period (i.e., the transmission opportunity is not equal to 0 for more than 20% of the detection interval duration at any one time).

[0088] It will be apparent to those skilled in the art that at least some embodiments can be practiced without these specific details. In other cases, well-known components, elements or methods are not described in detail or are presented in simple block diagram form to avoid unnecessarily obscuring the subject matter described herein. Therefore, the specific details described below are merely exemplary. Particular implementations may differ from these exemplary details and still be considered to be within the spirit and scope of the present embodiments.

[0089] References in the description to "an embodiment," "one embodiment," "an example embodiment," "some embodiments," and "various embodiments" mean that the particular feature, structure, step, act, or characteristic described in connection with that embodiment is included in at least one embodiment. Furthermore, appearances of the phrases "an embodiment," "one embodiment," "an example embodiment," "some embodiments," and "various embodiments" in various places in this specification do not necessarily all refer to the same embodiment.

[0090] The description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show illustrations by way of example embodiments. These embodiments, which may be referred to herein as "examples," are described in sufficient detail to enable one skilled in the art to practice the embodiments of the claimed subject matter described herein. The embodiments may be combined, other embodiments may be utilized, or structural, logical, and electrical changes may be made without departing from the scope and spirit of the claimed subject matter. It should be understood that the embodiments described herein are not intended to limit the scope of the subject matter, but rather to enable one skilled in the art to practice, make, and / or use the subject matter.

[0091] The description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show illustrations by way of example embodiments. These embodiments, which may be referred to herein as "examples," are described in sufficient detail to enable one skilled in the art to practice the embodiments of the claimed subject matter described herein. The embodiments may be combined, other embodiments may be utilized, or structural, logical, and electrical changes may be made without departing from the scope and spirit of the claimed subject matter. It should be understood that the embodiments described herein are not intended to limit the scope of the subject matter, but rather to enable one skilled in the art to practice, make, and / or use the subject matter.

[0092] Certain embodiments may be implemented by firmware instructions stored in a non-transitory computer-readable medium, such as, for example, a volatile memory and / or a non-volatile memory. These instructions may be used to program and / or configure one or more devices, including a processor (e.g., a CPU) or its equivalent (e.g., a processing core, a processing engine, a microcontroller, etc.). Non-transitory computer-readable storage media may include, but are not limited to, electromagnetic storage media, read-only memory (ROM), random access memory (RAM), erasable programmable memory (e.g., EPROM and EEPROM), flash memory, or other now known or later developed non-transitory types of media suitable for storing information.

[0093] Although the operations of the circuits and blocks herein are shown and described in a particular order, in some embodiments, the order of operations of each circuit / block may be changed such that certain operations may be performed in reverse order, or such that certain operations may be performed, at least in part, simultaneously and / or in parallel with other operations. In other embodiments, instructions or sub-operations of separate operations may be performed intermittently and / or alternatingly.

[0094] In the foregoing specification, the present disclosure has been described with reference to certain exemplary embodiments thereof. It will be apparent, however, that various modifications and changes may be made thereto without departing from the broader spirit and scope of the present disclosure as set forth in the appended claims. The specification and drawings are therefore to be regarded in an illustrative rather than a restrictive sense.

Claims

1. detecting radio frequency (RF) interference by detecting a period within a first detection interval during which there is no transmission opportunity, the period having a duration that satisfies a duration threshold; switching from the first bandwidth to a second bandwidth during a second detection interval; The method includes:

2. the first and second detection intervals are consecutive, and the first detection interval precedes the second detection interval. The method of claim 1.

3. The method comprises: determining whether an interference energy level of the second bandwidth meets a threshold interference energy level; switching from the first bandwidth to the second bandwidth during the second detection interval in response to determining that the interference energy level of the second bandwidth does not meet the threshold interference energy level; Further comprising: The method of claim 1.

4. the first bandwidth includes a plurality of subbands; the second bandwidth includes a subset of the plurality of subbands of the first bandwidth. The method of claim 1.

5. the interference energy level of the second bandwidth is a value stored in a register. The method according to claim 3.

6. The RF interference is continuous wave (CW) interference. The method of claim 1.

7. detecting radio frequency (RF) interference in a first bandwidth within a first detection interval; determining whether an interference energy level of the second bandwidth satisfies a threshold interference energy level; switching from the first bandwidth to the second bandwidth in response to determining during a second detection interval that the interference energy level of the second bandwidth does not meet the threshold interference energy level; The method includes:

8. the first and second detection intervals are consecutive, and the first detection interval precedes the second detection interval. The method according to claim 7.

9. the first bandwidth includes a plurality of subbands; the second bandwidth includes a subset of the plurality of subbands of the first bandwidth. The method according to claim 7.

10. the step of detecting RF interference in a first bandwidth within a first detection interval includes detecting a period within the first detection interval of no transmission opportunity, the period having a duration that satisfies a duration threshold. The method according to claim 7.

11. the interference energy level of the second bandwidth is a value stored in a register. The method according to claim 7.

12. The RF interference is continuous wave (CW) interference. The method according to claim 7.

13. a wireless module comprising a radio frequency (RF) circuit; a processing unit coupled to the RF circuit; A system comprising: the radio module detects RF interference by detecting a period within a first detection interval of no transmission opportunity, the period having a duration that meets a duration threshold, during which the RF circuitry operates at a first bandwidth; the processing unit switches the RF circuitry from operating at a first bandwidth to a second bandwidth during a second detection interval. system.

14. the first and second detection intervals are consecutive, and the first detection interval precedes the second detection interval. The system of claim 13.

15. The processing device further comprises: determining whether an interference energy level of the second bandwidth satisfies a threshold interference energy level; switching from the first bandwidth to the second bandwidth during the second detection interval in response to determining that the interference energy level of the second bandwidth does not meet the threshold interference energy level. The system of claim 13.

16. the first bandwidth includes a plurality of subbands; the second bandwidth includes a subset of the plurality of subbands of the first bandwidth. The system of claim 13.

17. the interference energy level of the second bandwidth is a value stored in a register. The system of claim 15.

18. the wireless module is a wireless local area network (WLAN) module; The system of claim 13.

19. The processing device includes firmware, the firmware comprising: switching the RF circuitry from operating at a first bandwidth to a second bandwidth during a second detection interval; The system of claim 13.

20. The RF interference is continuous wave (CW) interference. The system of claim 13.

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