WO2017080342A1

WO2017080342A1 - Channel sensing method and device

Info

Publication number: WO2017080342A1
Application number: PCT/CN2016/102181
Authority: WO
Inventors: 邢卫民; 吕开颖
Original assignee: 中兴通讯股份有限公司
Priority date: 2015-11-10
Filing date: 2016-10-14
Publication date: 2017-05-18
Also published as: CN106686746A

Abstract

The invention provides a channel sensing method and device. The channel sensing method comprises: detecting a transmission signal in a first sensing time interval t1; determining, according to results of comparing signal energy of the transmission signal with a first predefined threshold TH1 and a second predefined threshold TH2, a channel state, wherein TH1 is less than TH2; and when the channel state is undetermined in t1, extending t1 to a second sensing time interval t2, and sensing the channel state of a channel in t2, wherein t1 is less than t2. The embodiment resolves a problem of a flaw present in channel sensing in the related art owing to a lack of a quick sensing or recovery method for detecting WLAN signals having a plurality of physical characteristics, thereby achieving the effect of providing the quick sensing or recovery method for detecting WLAN signals having the plurality of physical characteristics.

Description

Channel detection method and device

Technical field

The present invention relates to the field of communications, and in particular to a method and apparatus for channel detection.

Background technique

A basic service set (BSS) of a Wireless Local Area Network (WLAN) is generally shown in FIG. 1. FIG. 1 is a structural diagram of a BSS in the related art, and generally includes an access point AP ( Access point) and multiple non-AP stations. At present, the Institute of Electrical and Electronics Engineers (IEEE) standards organization has set up a dedicated task force to develop the next generation of high efficiency WLAN (HEW) in order to solve the problem of WLAN network efficiency. Among them, an important technical feature of HEW is to use a narrower Orthogonal Frequency Division Multiplexing (OFDM) subcarrier spacing, so that there are more subcarriers under the same system bandwidth, which is beneficial to achieve more OFDMA. User transfer. However, a narrower subcarrier spacing also means a longer OFDM symbol, for example, when the subcarrier spacing becomes 1/4 of the original subcarrier spacing, and the OFDM symbol length also becomes about 4 times the original. Here, the signal of the narrow subcarrier spacing described above is referred to as an HE signal, and the signal of the subcarrier spacing of the previous WLAN is referred to as a Legacy signal.

In the related art, the WLAN uses the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) mechanism to contend for the access channel. The operation that must be performed during the contention process is to detect the channel state and determine that the channel is busy. The next-generation WLAN modifies the characteristics of the WLAN signal. The wireless frame is divided into two parts as the preamble of the physical characteristics of the symbol traditional WLAN signal, and the part is the preamble and the physical layer frame body of the HEW with narrower subcarrier spacing. The traditional preamble is retained, and the random back-off competition process is basically consistent with traditional equipment. However, the contention detection of WLAN devices is not a random backoff process. Sometimes, a fast detection access procedure may be used. For example, when an AP sends a beacon frame Beacon, or a channel test without a contention period, the detection time is short. To coordinate the interframe space (point (coordination function) interframe space (PIFS)), this can quickly access the channel. In addition, when a transmission error occurs during a successful transmission opportunity, recovery is required, and detection and rapid recovery are required. Transmission, at this time can also be detected using PIFS time. The above-mentioned fast detection and fast recovery process is related to the physical characteristics of the WLAN signal, in particular, to the OFDM symbol length. For example, the OFDM symbol in the WLAN generally has a guard interval (GI) or a cyclic prefix (cyclic prefix). The characteristics of CP) are based on these loops with certain regular signal characteristics as the basis for judging whether or not the WLAN signal is used. At present, there are both WLAN signals with traditional subcarrier spacing and WLAN signals with narrow subcarrier spacing. The physical characteristics are no longer single. Currently, there is no fast definition for WLAN signals with multiple physical characteristics in the network. Or quick recovery Complex method.

Summary of the invention

The embodiments of the present invention provide a method and a device for detecting a channel, so as to at least solve the problem of channel detection defects caused by the lack of a fast detection or fast recovery method for a WLAN signal that defines multiple physical characteristics in the related art.

According to an aspect of the embodiments of the present invention, a channel detection method is provided, including: detecting a transmission signal in a channel during a first detection period t1; and determining a signal energy according to the transmission signal and a first preset threshold TH1 And comparing the result of the channel with the second preset threshold TH2, wherein TH1 is smaller than TH2; and, when the state of the channel is not determined within t1, t1 is extended to the second detection period t2, and at t2 The channel state of the channel is detected internally, where t1 is less than t2.

Further, determining the state of the channel according to the comparison between the signal energy of the transmission signal and the first preset threshold TH1 and the second preset threshold TH2 includes: determining that the channel state is idle when the signal energy is less than TH1; When the signal energy is greater than TH2, it is determined that the channel state is busy; when the signal energy is in the preset threshold interval [TH1, TH2], it is determined whether the transmission signal detected at the first detection time t1 is the first type signal, according to the signal of the transmission signal. Type determines the channel status.

Further, determining whether the transmission signal detected at the first detection time t1 is a first type of signal, and determining the channel state according to the signal type of the transmission signal comprises: determining that the channel state is busy when determining that the transmission signal is the first type of signal.

Further, before detecting the channel state of the channel in t2, the method further comprises: when it is determined that the transmission signal is not the first type of signal, expanding t1 to t2, and continuing to detect the signal type of the transmission signal in the channel within t2.

Further, when the signal type of detecting the transmission signal is detected in the end of t1 to t2 or t2 is the first type of signal, it is determined that the channel state is busy.

Further, detecting the channel state of the channel in t2 includes: determining that the channel state is busy when detecting that the signal type of the transmission signal is the second type signal in t2; and detecting that the signal type of the transmission signal is not the second class in t2; When the signal is signaled, it is determined that the channel state is idle.

Further, when detecting that the signal type of the transmission signal is not the second type of signal in t2, determining that the channel state is idle includes: determining a signal type of detecting the transmission signal in t2; and when the signal type of the transmission signal is the second type of signal or In the first type of signal, the channel state is determined to be busy; when the signal type of the transmission signal is not the first type signal and the second type signal, the channel state is determined to be idle.

Further, the first type of signal is a signal conforming to the Orthogonal Frequency Division Multiplexing (OFDM) symbol length and the cyclic prefix format of the legacy legacy format.

Further, the second type of signal is a signal conforming to an orthogonal frequency division multiplexing OFDM symbol length and a cyclic prefix format of the efficient HE format.

Further, t1 is a maximum time length for determining whether the transmission signal is the first type of signal; t2 is determining that the transmission signal is No is the maximum length of time of the second type of signal; wherein, t1 is the point coordination interframe time PIFS or the in-frame detection time CCAMidTime; the value of t2 is greater than or equal to the length of the OFDM symbol and the cyclic prefix of the specified HE format.

Further, TH1 is a wireless local area network WLAN signal detection threshold or an overlapping basic service set packet detection threshold, and TH2 is a non-wireless local area network WLAN signal detection threshold or a signal energy detection threshold.

Further, before detecting the transmission signal in the channel at the first detection time t1, the method further includes: determining whether the channel state satisfies the condition for quickly detecting the access channel or the condition of preferentially accessing the channel.

According to another aspect of the embodiments of the present invention, an apparatus for detecting a channel includes: a detecting module configured to detect a transmission signal in a channel during a first detection period t1; and a first determining module configured to detect The result of comparing the signal energy of the transmission signal detected by the module with the first preset threshold TH1 and the second preset threshold TH2 determines the state of the channel, wherein TH1 is smaller than TH2; and the second determining module is set to When the state of the channel is not determined in t1, t1 is extended to the second detection period t2, and the channel state of the channel is detected in t2, where t1 is smaller than t2.

Further, the first determining module includes: a first determining unit, configured to determine that the channel state is idle when the signal energy is less than TH1, and the second determining unit, when the signal energy is greater than TH2, when TH1 is less than TH2 And determining that the channel state is busy; the third determining unit is configured to determine, when the signal energy is in the preset threshold interval [TH1, TH2], whether the transmission signal detected at the first detection time t1 is the first type signal, according to the transmission signal The signal type determines the channel status.

Further, the third determining unit includes: a first determining subunit configured to determine that the channel state is busy when determining that the transmission signal is the first type of signal.

Further, the apparatus further includes: a second determining subunit configured to expand t1 to t2 when it is determined that the transmission signal is not the first type of signal before detecting the channel state of the channel in t2, and continue to detect the channel within t2 The type of signal that transmits the signal.

Further, the apparatus further includes: a third determining subunit configured to determine that the channel state is busy when detecting that the signal type of the transmission signal is the first type of signal in the end of t1 to t2 or t2.

Further, the second determining module includes: a fourth determining unit, configured to determine that the channel state is busy when the signal type of the transmission signal is detected in t2 is a second type of signal; and the fifth determining unit is set to be within t2 When the signal type of the detected transmission signal is not the second type of signal, it is determined that the channel state is idle.

Further, the fifth determining unit includes: a fourth determining subunit, configured to determine a signal type for detecting a transmission signal in t2; and a fifth determining subunit, configured to: when the signal type of the transmission signal is a second type signal or the first When the signal is similar, the channel state is determined to be busy; the sixth determining subunit is set to determine that the channel state is idle when the signal type of the transmission signal is not the first type signal and the second type signal.

Further, the apparatus further includes: a third determining module, configured to determine whether the channel state satisfies the condition for quickly detecting the access channel or the condition for preferentially accessing the channel before detecting the transmission signal in the channel at the first detection time t1.

Through the invention, the transmission signal in the channel is detected during the first detection period t1; the signal according to the transmission signal The comparison result of the energy with the first preset threshold TH1 and the second preset threshold TH2 determines the state of the channel, wherein TH1 is smaller than TH2; and, when the state of the channel is not determined within t1, t1 is extended to The second detection period t2, and detecting the channel state of the channel in t2, where t1 is smaller than t2. The invention solves the problem of lack of channel detection defects caused by the lack of rapid detection or fast recovery of WLAN signals defining various physical characteristics in the related art, thereby achieving a rapid detection or fast recovery method for filling WLAN signals defining various physical characteristics. Effect.

DRAWINGS

The drawings described herein are intended to provide a further understanding of the invention, and are intended to be a part of the invention. In the drawing:

1 is a structural diagram of a BSS in the related art;

2 is a flowchart of a method of channel detection according to an embodiment of the present application;

3 is a schematic diagram of channel access provided by an embodiment of the present application;

4 is a schematic structural diagram of an OFDM symbol provided by an embodiment of the present application;

FIG. 5 is a schematic diagram of detection time in a frame provided by an embodiment of the present application; FIG.

6 is a structural block diagram of an apparatus for channel detection according to an embodiment of the present application;

FIG. 7 is a structural block diagram of an apparatus for channel detection according to an embodiment of the present application; FIG.

FIG. 8 is a structural block diagram of another apparatus for channel detection according to an embodiment of the present application; FIG.

FIG. 9 is a structural block diagram of still another apparatus for channel detection according to an embodiment of the present application; FIG.

FIG. 10 is a structural block diagram of another apparatus for channel detection according to an embodiment of the present application.

detailed description

The invention will be described in detail below with reference to the drawings in conjunction with the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments may be combined with each other without conflict.

It is to be understood that the terms "first", "second" and the like in the specification and claims of the present invention are used to distinguish similar objects, and are not necessarily used to describe a particular order or order.

Example 1

A method for channel detection is provided in this embodiment, and FIG. 2 is a method for channel detection according to an embodiment of the present application. The flow chart is shown in Figure 2. The process includes the following steps:

Step S202, detecting a transmission signal in the channel during the first detection period t1;

Step S204, determining a state of the channel according to a comparison result between the signal energy of the transmission signal and the first preset threshold TH1 and the second preset threshold TH2, wherein TH1 is smaller than TH2;

Step S206, when the state of the channel is not determined in t1, t1 is extended to the second detection period t2, and the channel state of the channel is detected in t2, where t1 is smaller than t2.

The method for channel detection provided by the embodiment of the present application can be applied to a wireless local area network (WLAN), in particular, an access point (AP) and a plurality of non-AP stations. In the basic service set (BSS) scenario, the first time, the signal characteristics are detected within a short period of time, and the channel can be quickly accessed as soon as possible. If the signal characteristics cannot be determined within the above time, the extended detection is performed. Time to be able to distinguish between WLAN signals and non-WLAN signals to avoid interference. The method can ensure the speed of the access channel of the station, and can avoid interference and improve the utilization efficiency of the channel.

Specifically, first, the transmission signal in the channel is detected in the first detection period t1, and secondly, the comparison between the signal energy of the transmission signal and the first preset threshold TH1 and the second preset threshold TH2 is determined. The state of the channel, where TH1 is less than TH2, and finally, when the state of the channel is not determined within t1, t1 is extended to the second detection period t2, and the channel state of the channel is detected within t2, where t1 is less than t2.

Through the above steps, the transmission signal in the channel is detected in the first detection period t1; the state of the channel is determined according to the comparison between the signal energy of the transmission signal and the first preset threshold TH1 and the second preset threshold TH2 Wherein TH1 is less than TH2; and, when the state of the channel is not determined within t1, t1 is extended to the second detection period t2, and the channel state of the channel is detected within t2, where t1 is less than t2. The invention solves the problem of lack of channel detection defects caused by the lack of rapid detection or fast recovery of WLAN signals defining various physical characteristics in the related art, thereby achieving a rapid detection or fast recovery method for filling WLAN signals defining various physical characteristics. Effect.

Further, determining the state of the channel according to the comparison between the signal energy of the transmission signal and the first preset threshold TH1 and the second preset threshold TH2 in step S204 includes:

Case 1, when the signal energy is less than TH1, it is determined that the channel state is idle;

Case 2, when the signal energy is greater than TH2, it is determined that the channel state is busy;

In the third case, when the signal energy is in the preset threshold interval [TH1, TH2], it is judged whether the transmission signal detected at the first detection time t1 is the first type signal, and the channel state is determined according to the signal type of the transmission signal.

Specifically, in the channel detection method provided by the embodiment of the present application, if the AP needs to access the current channel, whether there is a transmission signal in the current channel, and detecting the signal energy of the transmission signal, thereby determining the current channel. The signal state, that is, the detection channel state will occur in three cases: Case 1, detecting the signal energy of the transmission signal in the current channel to determine whether the signal energy is less than the first preset threshold TH1, when the signal energy is less than When TH1, the judgment letter The channel state is idle; in the second case, when the signal energy is greater than the second preset threshold TH2, the channel state is determined to be busy; in the third case, when the signal energy is in the preset threshold interval [TH1, TH2], The current first detection time t1 detects the signal type of the transmission signal, that is, whether it is the first type of signal, and determines the channel state according to the signal type. Here, the preset threshold provided by the embodiment of the present application, since the first preset threshold TH1 is smaller than the second preset threshold TH2, based on the case 1 and the case 2, the minimum range of the signal energy determination range is TH1, the maximum value. It is the preset threshold of TH2, that is, the preset threshold interval [TH1, TH2].

Further, in the third case, it is determined whether the transmission signal detected at the first detection time t1 is the first type of signal, and determining the channel state according to the signal type of the transmission signal includes:

When it is determined that the transmission signal is the first type of signal, it is determined that the channel state is busy.

Specifically, based on the foregoing case 3, when it is determined that the transmission signal in the current channel is the first type of signal, it is determined that the channel state is busy.

Further, before the detecting the channel state of the channel in t2 in step S206, the method for channel detection provided by the embodiment of the present application further includes:

When it is determined that the transmission signal is not the first type of signal, t1 to t2 are extended, and the signal type of the transmission signal in the channel is continuously detected in t2.

And whether the transmission signal is the first type of signal or not, when the transmission signal in the current channel is not the first type of signal, the t1 is extended to the t2 time period, and the transmission signal in the channel is continuously detected in the t2 time period. The type of signal.

In addition, different from the above, in the detection from t1 to t2 or t2, it can be determined whether there is a first type of signal in the current channel, and if the first type of signal exists, it is determined that the channel state of the channel is busy.

Further, detecting the channel state of the channel in t2 in step S206 includes:

Step1, when detecting that the signal type of the transmission signal is the second type signal in t2, determining that the channel state is busy;

Step 2: When it is detected that the signal type of the transmission signal is not the second type signal in t2, it is determined that the channel state is idle.

Specifically, in combination with Step1 and Step2, if it is determined in t2 that the signal conforms to the second type of signal characteristic, the channel is determined to be busy; if it is determined in t2 that the signal does not conform to the second type of signal characteristic, the channel is determined. For leisure.

The second type of signal characteristic, that is, the characteristics of the OFDM symbol of the High Efficiency (referred to as HE) format orthogonal frequency division multiplexing.

Further, when the signal type of the transmission signal is not detected in the second type in step 2, the channel state is determined to be idle:

Step1, determining the type of the signal for detecting the transmission signal in t2;

Step 2, when the signal type of the transmission signal is the second type signal or the first type signal, determining that the channel state is busy;

Step 3: When the signal type of the transmission signal is not the first type signal and the second type signal, it is determined that the channel state is idle.

Further, t1 is a maximum time length for determining whether the transmission signal is a first type of signal; t2 is a maximum time length for determining whether the transmission signal is a second type of signal; wherein t1 is a point coordination interframe interval time PIFS or intraframe detection The value of time CCAMidTime;t2 is greater than or equal to the length of the OFDM symbol and cyclic prefix of the specified HE format.

Further, before the first detection time t1 detects the transmission signal in the channel in the step S202, the method for channel detection provided by the embodiment of the present application further includes:

In step S201, it is determined whether the channel state satisfies the condition for quickly detecting the access channel or the condition for preferentially accessing the channel.

Here, when the current channel state cannot satisfy the condition for quickly detecting the access channel, or the condition for preferentially accessing the channel, step S202 to step S206 are performed to determine the channel of the current channel by measuring the signal energy of the transmission signal in the channel. Status, and access to the channel when the channel status is idle.

Specifically, the method for channel detection provided by the embodiment of the present application is applicable to scenario 1: AP fast access; and multiple non-AP site intra-frame detection is taken as an example, as follows:

Scenario 1, AP quick access:

An AP supporting the characteristics defined by the HEW establishes a BSS, and multiple non-AP STAs perform an association authentication process with the AP to form a basic service set BSS. Some of the STAs are new devices supporting the HE format radio frame, and some are traditional. Devices, such as 802.11ac/n/a/g devices.

Assuming that the AP has priority in contending for the channel, the fast access mechanism can be used to acquire the channel. Because there are both traditional devices and HE devices in the network, the AP should consider whether to detect whether there is a WLAN signal when detecting and accessing the channel quickly. transmission. The specific AP starts to detect the access process quickly. The AP performs channel detection in the next t1 time. At this time, the t1 time is the PIFS time. According to the detection result in t1, the AP operates as follows:

If the signal energy detected in t1 is less than the defined WLAN signal detection threshold (for example, the threshold value is -72 dBm in the 20 MHz bandwidth), whether the signal is WLAN or not, whether the channel is idle or not;

If the signal energy detected in the t1 time is greater than the defined non-WLAN signal detection threshold or the energy detection threshold (for example, the threshold value is -62 dBm in the 20 MHz bandwidth), whether the channel is busy or not, whether it is WLAN information or not;

If the signal energy detected in the t1 time is between the defined WLAN signal detection threshold and the non-WLAN signal detection threshold (energy detection threshold), and the determined signal in the t1 time is consistent with the characteristics of the traditional WLAN symbol, that is, The signal belongs to a part of a traditional WLAN radio frame, and the channel is determined to be busy;

If the signal energy detected in the t1 time is between the defined WLAN signal detection threshold and the non-WLAN signal detection threshold (energy detection threshold), and it is determined in t1 that the detected signal does not conform to the characteristics of the traditional WLAN symbol, If the signal does not belong to a part of the traditional WLAN radio frame, the detection time is extended to t2 for further detection, and the value of t2 is greater than or equal to the length of the OFDM symbol of the two longest HE formats, and the time is assumed to be 56 μs;

If the first three cases are mentioned above, the AP can determine that the channel is busy and idle in the time t1. If the fourth situation is the above, the AP needs to detect in the t2 time. According to the detection result in the t2, the AP operates as follows:

If it is determined in t2 that the detected signal conforms to the characteristics of the next generation WLAN symbol, that is, the signal belongs to a part of the HE radio frame, it is determined that the channel is busy;

If it is determined in t2 that the detected signal does not conform to the characteristics of the next generation WLAN symbol, that is, the signal does not belong to a part of the HE radio frame, it is determined that the channel is idle.

Scenario 2, multiple non-AP site intraframe detection:

An AP supporting the characteristics defined by the HEW establishes a BSS, and multiple non-AP STAs perform an association authentication process with the AP to form a basic service set BSS. Some of the STAs are new devices supporting the HE format radio frame, and some are traditional. Devices, such as 802.11ac/n/a/g devices. Assume that the STA1 is a station that supports the HE format radio frame, and the STA1 generates a transmission error in the competing TXOP, and uses the detection method defined by the present invention to access the channel. FIG. 3 is a schematic diagram of channel access provided by the embodiment of the present application, such as Figure 3 shows.

The STA1 uses the CSMA random access mechanism to contend for the channel. If the STA1 is successfully contending, the first frame is sent to the AP, and the AP sends a response frame to the STA1 after receiving the first frame. The first frame and its response frame contain the channel. The reservation information is reserved, and a TXOP is reserved for the transmission of STA1 and AP. STA1 will perform multiple frame exchanges with the AP during the reserved TXOP time. Assume that STA1 sends the second frame to the AP, but does not correctly receive the response frame sent by the AP, STA1 determines that the second frame transmission fails, and starts to quickly detect the access process. It should be noted that the STA1 determines that the second frame transmission fails. There are two cases. One case is that STA1 does not detect any response after the second frame is sent. In the other case, after the second frame is sent, STA1 detects the response, but the response is not the desired response frame. Specifically, STA1 determines that the second frame transmission fails, and performs channel detection in the next t1 time. At this time, t1 time is PIFS time or CCAMidTime. According to the detection result in t1, STA1 operates as follows:

Case 1, if the signal energy detected in t1 is less than the defined WLAN signal detection threshold (for example, the threshold value is -72 dBm in the 20 MHz bandwidth), whether the signal is WLAN or not, whether the channel is idle or not;

Case 2, if the signal energy detected in time t1 is greater than the defined non-WLAN signal detection threshold or energy detection gate Limit (for example, the threshold value is -62dBm in the 20MHz bandwidth), whether the channel is busy or not, whether it is WLAN information or not;

Case 3, if the signal energy detected in t1 is between the defined WLAN signal detection threshold and the non-WLAN signal detection threshold (energy detection threshold), and the detected signal conforms to the characteristics of the conventional WLAN symbol within t1 time. , that is, the signal belongs to a part of a traditional WLAN radio frame, and then the channel is determined to be busy;

Case 4, if the signal energy detected in t1 is between the defined WLAN signal detection threshold and the non-WLAN signal detection threshold (energy detection threshold), and it is determined in t1 that the detected signal does not conform to the traditional WLAN symbol. The characteristic is that the signal does not belong to a part of the traditional WLAN radio frame, and the detection time is extended to t2 for further detection, and the value of t2 is greater than or equal to the length of the OFDM symbol of the two longest HE formats, and the assumed time is 56 μs;

If it is the first three cases, STA1 can judge that the channel is busy and idle in t1 time. For example, in the first case, STA1 can continue to send radio frames after t1 time after determining that the transmission fails, and the fast access channel. .

Assuming the fourth case described above, STA1 detects in time t2. According to the detection result in t2, STA1 operates as follows:

If it is determined in t2 that the detected signal does not conform to the characteristics of the next generation WLAN symbol, that is, the signal does not belong to a part of the HE radio frame, then the channel is determined to be idle;

In addition, during the end period from the end of t1 to the end of t2, other stations may start a new transmission. In order to be able to detect the transmission, the detection station may need to continue to detect the traditional frame format during this period, that is, whether the time from t1 to t2 is determined. A signal with a conventional WLAN, if present, determines that the channel is busy. If it is determined that there is no legacy or next generation WLAN signal in t2, then the channel is determined to be idle.

Assuming that the channel is idle during t2, STA1 can continue to transmit radio frames after t2 time, and quickly access the channel, as illustrated in FIG.

As shown in FIG. 3, according to the method of the present invention, the actual channel detection time may be t1 or t2, and both the traditional WLAN signal and the HE signal may be detected. When a transmission error occurs in the TXOP, It can guarantee the reliability of channel detection during fast recovery. In addition, the above quick recovery process, AP and site are applicable.

In addition, the WLAN uses a carrier sense multiple access mechanism (CSMA with Collision Avoidance, CSMA/CA) with collision avoidance to enable multiple stations to share a wireless channel. The process of the station competing for the transmission opportunity is that the station first detects the channel, only in the The channel is determined to be idle for a period of time to start transmitting. The period of time is generally equal to an interframe interval plus a random backoff time, and the random backoff time is n slots of the detection slot, where n is a random integer. Its value conforms to the uniform distribution [0, CW], CW is the contention window, and CW is a positive integer.

In addition to the contention-based random access procedure described above, the WLAN also defines that the station can access the channel quickly or preferentially under certain special circumstances, specifically defining a fixed detection duration, such as PIFS time or CCAMidTime (in the frame detection time). In the meantime, for a traditional site, both are equal to 25μs. The case of the fast access channel may be, but is not limited to, the following:

The station sends a special frame, such as an AP sending a Beacon frame, a channel switching frame, and the like.

The current access period is a non-competition period defined by the network, such as CFP (contention free period), SP (service period)

When a transmission error occurs within a time period of an already acquired transmission period, fast recovery is performed, for example, error recovery is performed within an acquired transmission opportunity (TXOP).

When the network operates at a large bandwidth, the secondary channel is detected before the large bandwidth data is transmitted. For example, when the transmission bandwidth is 40 MHz and random access contention is used on the primary 20 MHz channel, the detection on the secondary channel can be made simpler, and fast detection can be used.

In the embodiment of the present application, it is assumed that the next-generation WLAN station supports the radio frame of the HE format, that is, the radio frame with the narrow sub-carrier spacing, and also supports the radio frame of the traditional legacy format, that is, the radio frame of the normal sub-carrier interval, and the specific site mentioned above. That is, the 312.5 kHz subcarrier spacing is supported, and the 78.125 kHz subcarrier spacing is also supported. The symbol period of the two is inversely proportional to the subcarrier spacing. FIG. 4 is a schematic structural diagram of the OFDM symbol provided by the embodiment of the present application, as illustrated in FIG. When the above-mentioned station determines that the current access channel is the above-mentioned case where fast detection can be used, the channel can be accessed quickly or preferentially. However, since the fast detection is related to the subcarrier spacing, that is, the symbol period, when the next generation WLAN station performs fast detection and accesses the channel, the method for using the fast access channel with non-fixed detection duration defined by the present invention is used. .

Based on the above, the relationship between the values of the detection times t1 and t2 and the fast detection provided by the embodiments of the present application is as follows:

Fast detection can also be called intra-frame detection CCA-Middle. The radio frame transmitted by the WLAN station includes the frame header preamble and the frame body. The start of the frame header is a training field. The signal format of the domain is that all stations have It is known that the format of the training domain sent by all WLAN stations is the same. When the WLAN station contends for the channel, it is judged whether there is a signal transmission, which is mainly to detect the above-mentioned pre-training domain for judgment. However, in many cases, the time at which the station performs the detection is likely to be in the frame of the radio frame, that is, the frame header is missed, and the content of the frame body is the data portion of the transmission, which is generally an unknown signal, and the detection is difficult, and the fast detection is to consider the frame. Detection, that is, detecting the frame body of the WLAN signal, and being able to determine whether the signal is transmitted by the WLAN device.

In-frame detection utilizes a guard interval GI between OFDM symbols in a frame body, which is used to avoid interference between OFDM symbols before and after, but the interval is not empty, but the latter 1 of an OFDM symbol /N is copied to the front of the OFDM symbol, so it is also called a cyclic prefix. Thus, for the OFDM symbol in the frame body, the back 1/N of the OFDM symbol and the GI are repeated, so that the period of the OFDM symbol and the like can be determined by the correlation detection of the repeated part, thereby determining whether the frame is a physical medium defined by the symbol WLAN signal. The value of the N is generally equal to 4, 8, and 16 values. FIG. 5 is a schematic diagram of the detection time in the frame provided by the embodiment of the present application, as shown in FIG. 5 .

The time required for the detection in the frame is actually the time required to detect one OFDM symbol and the corresponding cyclic prefix. As shown in FIG. 4, it is necessary to ensure that at least one complete OFDM symbol plus CP is detected, and the detection time is at least Twice The length of the OFDM symbol plus the time of the CP. In addition to other processing delays and other factors, it is generally required that the detection length be greater than the minimum length.

The next-generation WLAN defines a new OFDM symbol format, and the signals of the conventional OFDM symbol format are still widely used, and the intra-frame detection method when two OFDM symbol formats coexist is considered, so that the detection time in the conventional frame cannot be detected. Longer HE symbols should also avoid longer channel access times due to longer detection times. In the present invention, a variable length intra-frame detection method is designed. Firstly, the detection is performed according to the length of the conventional OFDM symbol in t1, and the signal energy and symbol characteristics are judged. If it is possible to judge busy, no longer channel detection is performed, and the method is fast. Judging and quickly accessing the channel when the channel is idle, when the signal in t1 cannot determine whether it belongs to the WLAN signal, the detection time is extended to the time t2, and the time is detected in the frame based on the length of the OFDM symbol in the HE format. Furthermore, it is determined whether the signal belongs to a signal transmitted by the HE WLAN station, thus avoiding missed detection of the WLAN signal.

It should be noted that, in this embodiment, it is assumed that the detection in the frame uses the characteristics of the OFDM symbol CP to detect and determine whether the signal is a WLAN signal, but does not exclude the use of other OFDM symbol characteristics for signal format determination, such as a null subcarrier of the OFDM symbol. Frequency, etc., the response detection time t1, t2 can also be adjusted accordingly.

Based on the corresponding embodiment of FIG. 2, the embodiment of the present application is used to describe the relationship between the values of the signal thresholds TH1 and TH2 and the fast detection, as follows:

Fast detection or intra-frame detection detects the signal in a short time, and judges the energy of the signal, and also determines the physical characteristics or format of the signal, and then judges whether the wireless channel is available according to the two. The main purpose of the detection in the frame is to determine whether the detected signal is a signal transmitted by the WLAN device:

If the signal is sent by the WLAN device, a lower threshold is used to judge that the channel is busy, so as to avoid interference between the WLAN devices.

If it is not a signal sent by the WLAN device, a higher threshold is used to judge that the channel is busy, so that the channel can be accessed as much as possible, and the influence of devices such as an induction cooker is prevented, and the channel cannot be accessed.

In the embodiment of the present application, the threshold TH1 may be a WLAN signal detection threshold defined by the protocol, and the threshold TH2 may be a non-WLAN signal detection threshold. In addition, for the WLAN signal detection threshold, since the detection in the frame generally occurs on the detection of the OBSS signal, it may also be referred to as an overlapping basic service packet detection threshold (OBSS-PD); for a non-WLAN signal The detection threshold, because the signal can not be detected, the station can only detect energy, so it can also be called the energy detection threshold (ED).

In addition, the foregoing TH1 and TH2 may be non-fixed values, and may vary according to various situations. For example, the basic bandwidth of the WLAN is 20 MHz, but may be on a large bandwidth of 160 MHz, wherein the large bandwidth includes one primary 20 MHz channel, one or more. For a secondary 20 MHz channel, the values of TH1 and TH2 on the primary channel may be different from those on the secondary channel. The AP or the station can also adjust the values of TH1 and TH2 according to factors such as network load and interference.

In addition, the intra-frame detection method proposed in the embodiment of the present application can also be used for detecting when multiple networks coexist. For example, a network established by a WLAN network and LTE in an unlicensed band, including LTE-U (Long Term Evolution unlicensed), LAA (Licensed-Assisted Access) and the like.

Since the WLAN is different from the OFDM symbol defined by LTE, when the two are operating in the same frequency band, there will be a problem of mutual detection, such that a plurality of OFDM symbols appear in one frequency band, and the method of the present invention is applied to a WLAN device. When performing intra-frame detection or fast detection, intra-frame detection can be performed according to the symbol length defined by LTE. Similarly, the method of the present invention is applied to a device in which LTE operates in an unlicensed band, such as an LAA site, and the general process is:

Selecting an appropriate detection time t1 according to the OFDM symbol characteristics and length of the WLAN, and determining whether the channel is occupied by the WLAN station according to the relevant threshold, and then determining whether to extend the detection time to t2 or longer according to the detection result in t1. The change time is sufficient for the LAA site to determine whether there is a signal from the HEW device or other LAA device being transmitted.

Example 2

Through the description of the above embodiments, those skilled in the art can clearly understand that the method according to the above embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, by hardware, but in many cases, the former is A better implementation. Based on such understanding, the technical solution of the present invention, which is essential or contributes to the prior art, may be embodied in the form of a software product stored in a storage medium (such as ROM/RAM, disk, The optical disc includes a number of instructions for causing a terminal device (which may be a cell phone, a computer, a server, or a network device, etc.) to perform the methods described in various embodiments of the present invention.

A device for channel detection is also provided in this embodiment, and the device is configured to implement the foregoing embodiments and preferred embodiments, and details are not described herein. As used below, the term "module" may implement a combination of software and/or hardware of a predetermined function. Although the apparatus described in the following embodiments is preferably implemented in software, hardware, or a combination of software and hardware, is also possible and contemplated.

FIG. 6 is a structural block diagram of an apparatus for detecting a channel according to an embodiment of the present application. As shown in FIG. 6, the apparatus includes: a detecting module 62, a first determining module 64, and a second determining module 66, where

The detecting module 62 is configured to detect a transmission signal in the channel during the first detection period t1;

The first judging module 64 is configured to determine the state of the channel according to the comparison between the signal energy of the transmission signal detected by the detecting module and the first preset threshold TH1 and the second preset threshold TH2, wherein TH1 is less than TH2; as well as,

The second judging module 66 is configured to extend t1 to the second detecting period t2 when the state of the channel is not determined within t1, and detect the channel state of the channel in t2, where t1 is smaller than t2.

The device for channel detection provided by the embodiment of the present application detects a transmission signal in a channel during a first detection period t1; and according to a signal energy of the transmission signal, a first preset threshold TH1 and a second preset threshold TH2 The comparison result determines the state of the channel, wherein TH1 is smaller than TH2; and, when the state of the channel is not determined in t1, t1 is extended to the second detection period t2, and the channel state of the channel is detected in t2, wherein T1 is less than t2. Solved the lack of definition in related technologies The rapid detection or fast recovery method of WLAN signals with various physical characteristics brings about the problem of channel detection defects, thereby achieving the effect of filling the fast detection or fast recovery method of WLAN signals defining various physical characteristics.

Further, FIG. 7 is a structural block diagram of an apparatus for channel detection according to an embodiment of the present application. As shown in FIG. 7, the first determining module 64 includes: a first determining unit 641, a second determining unit 642, and a third determining Unit 643, wherein

The first determining unit 641 is configured to determine that the channel state is idle when the signal energy is less than TH1 when TH1 is less than TH2;

The second determining unit 642 is configured to determine that the channel state is busy when the signal energy is greater than TH2;

The third determining unit 643 is configured to determine, when the signal energy is in the preset threshold interval [TH1, TH2], whether the transmission signal detected at the first detection time t1 is the first type signal, and determine the channel state according to the signal type of the transmission signal. .

Further, FIG. 8 is a structural block diagram of another apparatus for channel detection according to an embodiment of the present application. As shown in FIG. 8, the third determining unit 643 includes: a first determining subunit 6431, where

The first judging subunit 6431 is configured to determine that the channel state is busy when it is determined that the transmission signal is the first type of signal.

Further, as shown in FIG. 8, the apparatus for channel detection in the embodiment of the present application further includes: a second determining subunit 6432, wherein

The second judging subunit 6432 is arranged to expand t1 to t2 when it is determined that the transmission signal is not the first type of signal before detecting the channel state of the channel in t2, and continue to detect the signal type of the transmission signal in the channel in t2.

Further, as shown in FIG. 8, the apparatus for channel detection in the embodiment of the present application further includes: a third determining subunit 6433, wherein

The third judging subunit 6433 is configured to determine that the channel state is busy when the signal type of detecting the transmission signal is detected in the end of t1 to t2 or t2 is the first type of signal.

Further, FIG. 9 is a structural block diagram of another apparatus for channel detection according to an embodiment of the present application. As shown in FIG. 9, the second determining module 66 includes: a fourth determining unit 661 and a fifth determining unit 662, where

The fourth determining unit 661 is configured to determine that the channel state is busy when detecting that the signal type of the transmission signal is the second type signal in t2;

The fifth determining unit 662 is configured to determine that the channel state is idle when the signal type of the detected transmission signal is not the second type of signal in t2.

Further, the fifth determining unit 662 includes:

a fourth determining subunit, configured to determine a signal type for detecting a transmission signal in t2;

a fifth determining subunit, configured to determine that the channel state is busy when the signal type of the transmission signal is the second type signal or the first type of signal;

The sixth determining subunit is configured to determine that the channel state is idle when the signal type of the transmission signal is not the first type signal and the second type signal.

Further, FIG. 10 is a structural block diagram of another apparatus for channel detection according to an embodiment of the present application. As shown in FIG. 10, the apparatus for channel detection in the embodiment of the present application further includes: a third determining module 61, where

The third determining module 61 is configured to determine whether the channel state satisfies the condition for quickly detecting the access channel or the condition for preferentially accessing the channel before detecting the transmission signal in the channel at the first detection time t1.

It should be noted that each of the above modules may be implemented by software or hardware. For the latter, the foregoing may be implemented by, but not limited to, the foregoing modules are all located in the same processor; or, the modules are located in multiple In the processor.

Embodiments of the present invention also provide a storage medium. Optionally, in the embodiment, the foregoing storage medium may be configured to store program code for performing the following steps:

S1. Detecting a transmission signal in the channel during the first detection period t1;

S2, determining a state of the channel according to a comparison result between the signal energy of the transmission signal and the first preset threshold TH1 and the second preset threshold TH2, wherein TH1 is smaller than TH2;

S3, when the state of the channel is not determined in t1, t1 is extended to the second detection period t2, and the channel state of the channel is detected in t2, where t1 is smaller than t2.

Optionally, the storage medium is further arranged to store program code for performing the following steps:

S1, when the signal energy is less than TH1, determining that the channel state is idle;

S2, when the signal energy is greater than TH2, determining that the channel state is busy;

S3, when the signal energy is in the preset threshold interval [TH1, TH2], determine whether the transmission signal detected at the first detection time t1 is the first type signal, and determine the channel state according to the signal type of the transmission signal.

Optionally, in this embodiment, the foregoing storage medium may include, but not limited to, a USB flash drive, a Read-Only Memory (ROM), a Random Access Memory (RAM), a mobile hard disk, and a magnetic memory. A variety of media that can store program code, such as a disc or a disc.

Optionally, in this embodiment, the processor performs, according to the stored program code in the storage medium, whether the transmission signal detected at the first detection time t1 is a first type of signal, and determining the channel state according to the signal type of the transmission signal includes: : When it is determined that the transmission signal is the first type of signal, it is determined that the channel state is busy.

Optionally, in this embodiment, before the processor performs the channel state of detecting the channel in t2 according to the stored program code in the storage medium, when determining that the transmission signal is not the first type of signal, the processor expands t1 to t2, and The signal type of the transmission signal in the channel continues to be detected in t2.

Optionally, in this embodiment, the processor performs, according to the stored program code in the storage medium, when the signal type detected in the end of t1 to t2 or the detection of the transmission signal in t2 is the first type of signal, determining the channel. The status is busy.

Optionally, in this embodiment, the performing, by the processor, the channel state of detecting the channel in t2 according to the stored program code in the storage medium includes: determining, when the signal type of the transmission signal is the second type of signal in t2, determining The channel state is busy; when the signal type of the transmission signal is detected in t2 is not the second type of signal, it is determined that the channel state is idle.

Optionally, in this embodiment, the processor executes, according to the stored program code in the storage medium, when the signal type of detecting the transmission signal in t2 is not the second type of signal, determining that the channel state is idle includes: determining that the value is within t2. Detecting a signal type of the transmission signal; determining that the channel state is busy when the signal type of the transmission signal is the second type signal or the first type signal; and determining when the signal type of the transmission signal is not the first type signal and the second type signal The channel status is idle.

Optionally, in this embodiment, the processor performs, according to the stored program code in the storage medium, whether to determine whether the channel state satisfies the condition for quickly detecting the access channel or prioritizes before detecting the transmission signal in the channel at the first detection time t1. The conditions for accessing the channel.

For example, the specific examples in this embodiment may refer to the examples described in the foregoing embodiments and the optional embodiments, and details are not described herein again.

It will be apparent to those skilled in the art that the various modules or steps of the present invention described above can be implemented by a general-purpose computing device that can be centralized on a single computing device or distributed across a network of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. The steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps thereof are fabricated as a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software.

The above description is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Industrial applicability

As described above, the method and apparatus for channel detection provided by the embodiments of the present invention have the following beneficial effects: filling a fast detection or fast recovery method for a WLAN signal defining multiple physical characteristics.

Claims

A method for channel detection, comprising:

Detecting a transmission signal in the channel during the first detection period t1;

Determining a state of the channel according to a comparison result between a signal energy of the transmission signal and a first preset threshold TH1 and a second preset threshold TH2, wherein the TH1 is smaller than TH2;

When the state of the channel is not determined in the t1, the t1 is extended to the second detection period t2, and the channel state of the channel is detected in the t2, wherein the t1 is smaller than the T2.
The method according to claim 1, wherein the determining the state of the channel according to the comparison between the signal energy of the transmission signal and the first preset threshold TH1 and the second preset threshold TH2 comprises:

When the signal energy is less than the TH1, determining that the channel state is idle;

Determining that the channel state is busy when the signal energy is greater than the TH2;

Determining whether the transmission signal detected at the first detection time t1 is a first type signal when the signal energy is in a preset threshold interval [TH1, TH2], and determining the signal according to a signal type of the transmission signal Channel status.
The method according to claim 2, wherein the determining whether the transmission signal detected at the first detection time t1 is a first type of signal, and determining the channel state according to a signal type of the transmission signal comprises:

When it is determined that the transmission signal is the first type of signal, it is determined that the channel state is busy.
The method of claim 2, wherein before the detecting the channel state of the channel in the t2, the method further comprises:

When it is determined that the transmission signal is not the first type of signal, the t1 to the t2 are extended, and the signal type of the transmission signal in the channel is continuously detected within the t2.
The method of claim 4 wherein the method further comprises:

When the signal type of the transmission signal is detected in the end of the t1 or in the t2 or the t2 is the first type of signal, it is determined that the channel state is busy.
The method of claim 4, wherein detecting a channel state of the channel within the t2 comprises:

Determining that the channel state is busy when detecting that the signal type of the transmission signal is the second type of signal in the t2;

When it is detected in the t2 that the signal type of the transmission signal is not the second type of signal, it is determined that the channel state is idle.
The method according to claim 6, wherein said determining that said channel state is idle comprises: when detecting that said signal type of said transmission signal is not said second type of signal within said t2:

Determining a signal type of detecting the transmission signal in the t2;

Determining that the channel state is busy when a signal type of the transmission signal is the second type signal or the first type signal;

When the signal type of the transmission signal is not the first type signal and the second type signal, it is determined that the channel state is idle.
The method of claim 2, wherein the first type of signal is a signal conforming to a Orthogonal Frequency Division Multiplexing (OFDM) symbol length and a cyclic prefix format of a legacy legacy format.
The method of claim 6, wherein the second type of signal is a signal conforming to an orthogonal frequency division multiplexing OFDM symbol length and a cyclic prefix format of the efficient HE format.
The method according to claim 9, wherein said t1 is a maximum time length for determining whether said transmission signal is said first type of signal; said t2 is determining whether said transmission signal is said second type of signal The maximum length of time; wherein the t1 is a point coordination interframe time PIFS or an in-frame detection time CCAMidTime; the value of the t2 is greater than or equal to the length of the OFDM symbol and the cyclic prefix of the specified HE format.
The method according to claim 2, wherein the TH1 is a wireless local area network WLAN signal detection threshold or an overlapping basic service set packet detection threshold, and the TH2 is a non-wireless local area network WLAN signal detection threshold or a signal energy detection threshold.
The method of claim 1, wherein before detecting the transmission signal in the channel at the first detection time t1, the method further comprises:

Determining whether the channel state satisfies a condition for quickly detecting access to the channel or preferentially accessing the channel.
A channel detecting apparatus includes:

a detecting module, configured to detect a transmission signal in the channel during the first detecting period t1;

The first determining module is configured to determine a state of the channel according to a comparison result between a signal energy of the transmission signal detected by the detecting module and a first preset threshold TH1 and a second preset threshold TH2, wherein , the TH1 is less than TH2; and,

a second determining module, configured to extend the t1 to a second detection period t2 when the state of the channel is not determined in the t1, and detect a channel state of the channel in the t2, where The t1 is smaller than the t2.
The apparatus of claim 13, wherein the first determining module comprises:

a first determining unit, configured to determine that the channel state is idle when the signal energy is less than the TH1;

a second determining unit, configured to determine that the channel state is busy when the signal energy is greater than the TH2;

The third determining unit is configured to determine, when the signal energy is in the preset threshold interval [TH1, TH2], whether the transmission signal detected at the first detection time t1 is a first type signal, according to the transmission The signal type of the signal determines the channel state.
The apparatus according to claim 14, wherein said third determining unit comprises:

The first determining subunit is configured to determine that the channel state is busy when it is determined that the transmission signal is the first type of signal.
The apparatus of claim 14 wherein said apparatus further comprises:

a second determining subunit, configured to expand the t1 to the t2 when determining that the transmission signal is not the first type of signal before detecting the channel state of the channel in the t2, and in the The signal type of the transmission signal within the channel continues to be detected within t2.
The apparatus of claim 16 wherein said apparatus further comprises:

The third determining subunit is configured to determine that the channel state is busy when the signal type of detecting the transmission signal in the t2 is detected in the t2 or in the t2 is the first type of signal.
The apparatus of claim 16, wherein the second determining module comprises:

a fourth determining unit, configured to determine that the channel state is busy when detecting that the signal type of the transmission signal is the second type signal in the t2;

The fifth determining unit is configured to determine that the channel state is idle when the signal type of the transmission signal is not detected in the t2.
The apparatus according to claim 18, wherein said fifth determining unit comprises:

a fourth determining subunit, configured to determine a signal type of detecting the transmission signal in the t2;

a fifth determining subunit, configured to determine that the channel state is busy when a signal type of the transmission signal is the second type signal or the first type signal;

And a sixth determining subunit, configured to determine that the channel state is idle when a signal type of the transmission signal is not the first type signal and the second type signal.
The device of claim 13 wherein said device further comprises:

The third determining module is configured to determine whether the channel state satisfies a condition for quickly detecting access to the channel or preferentially accessing the channel before detecting a transmission signal in the channel at the first detecting time t1.