JP6707958B2 - Method, apparatus and system for identifying hidden terminal - Google Patents

Description

The present invention relates to the field of communication technology, and more particularly, to a method, an apparatus and a system for identifying a hidden terminal.

A hidden terminal problem or a hidden node problem or a hidden station problem may occur when a wireless node cannot listen to other nodes, which may cause medium access control, eg carrier sense multiple access. / Collision avoidance (CSMA/CA, Carrier Sense Multiple Access with Collision Avoidance) may not be able to work properly. When such a situation occurs, multiple nodes attempt to transmit their data simultaneously on a shared medium, which may cause signal interference between each other.

Taking FIG. 1 as an example, the nodes A and B are all located within the communication range of the access point AP, but since there is no physical connection between these two nodes, they cannot communicate with each other. Also, because the two nodes are either distant from each other or there is a failure between them, it is not possible to listen to the other party, which makes them two nodes hidden with respect to the other party. The problem is that when these two nodes start sending data packets to the access point AP at the same time, they are out of range of the other party, so when they send data packets they cannot detect the collision. , CSMA/CD (Carrier Sense Multiple Access with Collision Detection) does not work, which may cause a collision and deteriorate the quality of data received by the access point AP.

There is a hidden terminal problem in many wireless systems, and these systems generally use the CSMA/CA mechanism to access the channel, eg, IEEE 802.11, 802.15.4, 802.15.6. IEEE 802.11 partially solves the hidden terminal problem by using the acknowledgedgment of 802.11 RTS/CTS (Request To Send/Clear To Send) and the handshake packet, but RTS/CTS is a complete solution. None, and introduces a large amount of overhead into the network, which may reduce throughput.

In order to solve the above-mentioned problems, the embodiments of the present invention provide a method, an apparatus and a system for identifying a hidden terminal, thereby assisting in diagnosing a failure or reducing performance of a CSMA/CA wireless network. Can solve the problem.

According to a first aspect of the present invention, there is provided a device for identifying hidden terminals,
The device is used for a station in a CSMA/CA wireless network, of which the device is
A statistical unit for statistically obtaining a ratio of frames for which an acknowledgment has not been received within a measurement window; and when the ratio is greater than a preset first threshold, in the CSMA/CA wireless network A transmitting unit for transmitting a frame time information report to an access point (AP), the frame time information report including timing information of a frame transmitted in the measurement window, whereby the AP is A transmitting unit is included for determining whether there is a hidden terminal for the station based on the timing information.

According to a second aspect of the present invention, there is provided a device for identifying a hidden terminal,
The device is used for an access point in a CSMA/CA wireless network, of which the device is
A first determining unit for determining a measurement window of the frame time information report based on a received frame time information report transmitted by a station in the CSMA/CA wireless network;
A comparison unit for comparing the timing information of each frame in the frame time information report with the previously stored timing information of the frame received within the measurement window; and the frame time information for the received frame. A second determining unit for determining that the station that transmitted the collision frame is a hidden terminal for the station when there is a frame that collides with the frame being reported and the collision rate is greater than a second threshold. including.

The beneficial effects of the present invention can aid in the diagnosis of failures or solve the problem of degraded performance of CSMA/CA wireless networks.

It is a figure which shows a hidden terminal problem. 5 is a follow chart of a method of identifying a hidden terminal in the first embodiment. 9 is a follow chart of a method of identifying a hidden terminal in the second embodiment. It is a figure which shows an example of an identification hidden terminal. It is a figure which shows the other example of an identification hidden terminal. FIG. 9 is a configuration diagram of an identification hidden terminal in the third embodiment. FIG. 9 is a configuration diagram of an identification hidden terminal according to the fourth embodiment. FIG. 9 is a configuration diagram of a station according to a fifth embodiment. FIG. 16 is a configuration diagram of an access point according to the sixth embodiment. It is a topology diagram of a CSMA/CA wireless network system.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

In the embodiment of the present invention, for convenience, an access point (AP, Access Point) is used to represent the infrastructure of the wireless network, and a station is used to represent the covered and served wireless device. It also uses the terms in IEEE 802.11. Those skilled in the art should understand that the embodiments of the present invention are not limited to IEEE 802.11 and can be applied to other wireless communication systems.

This embodiment provides a method for identifying hidden terminals, which is used for stations in CSMA/CA wireless networks. FIG. 2 is a follow chart of the method. As shown in FIG. 2, the method includes the following steps.

Step 201: Acquire statistically the ratio of frames that have not received an acknowledgment within the measurement window;
Step 202: Send a frame time information report to an access point (AP) in the CSMA/CA wireless network if the ratio is greater than a preset first threshold, and the frame time information report is transmitted in the measurement window. Including the timing information of the frame transmitted within the AP, the AP determines whether there is a hidden terminal for the station based on the timing information.

In this embodiment, for each frame transmitted by a station, the station can receive one acknowledgment. If, for one frame transmitted by the station, the station has not received its acknowledgment, there may be a link failure, or there may be a station failure, or The hidden terminal problem as described above may occur.

In step 201, the station can statistically obtain the ratio of frames that have not received an acknowledgment within the measurement window, for example, the number of frames transmitted by the station within a measurement window is A, If the number of frames receiving the acknowledgment is B, the station statistically determines that the ratio of frames not receiving the acknowledgment within the measurement window is (AB)/A. be able to. In the ideal case, the ratio is 0, that is, the acknowledgments have been received for all frames transmitted by the station.

Each measurement window corresponds to one time period, and the window index (Window) or the window start time and duration is used as an indicator of the measurement window.

In step 202, the station compares the ratio obtained in step 201 with a preset threshold value (in this embodiment, for convenience, referred to as a first threshold value), and the ratio is the first threshold value. If greater, the station sends a frame time information report to the access point, the frame time information report including timing information for frames transmitted within the measurement window.

Among them, the frames transmitted in the measurement window may be all the frames transmitted by the station in the measurement window, that is, the A frames described above; or the station may transmit in the measurement window. It may be a frame that has been transmitted but has not received the reception confirmation, that is, the AB frames described above.

The timing information of the frame may include a transmission time (start time) and a duration (duration) of the frame. Optionally, the duration may be replaced by the frame length and the data rate, i.e. the duration may be calculated by the frame length and the data rate.

The frame time information report may include information for indicating the measurement window, for example, the index of the measurement window described above, or the start time and duration of the measurement window, or , Other information for indicating the measurement window may be included.

Among them, the access point AP, after receiving the frame time information report, can determine whether or not there is a hidden terminal for the station based on the above-mentioned timing information. Example will be described.

In the present embodiment, the access point may further transmit synchronization timing information in order to achieve synchronization between the access point and the station, so that the station receiving the synchronization timing information is based on the synchronization timing information. Then, the access point and the measurement window can be synchronized, in which case the method of the present embodiment further comprises the following steps:
Step 200: Receive the synchronization timing information transmitted by the access point, and synchronize the access point and the measurement window based on the synchronization timing information.

Among them, as described above, the measurement window may be indicated by the measurement start time and period or may be indicated by the window index, in which case, in step 200, the station, based on the synchronization timing information, The measurement start time and period may be synchronized with the access point, and the access point and the window index may be synchronized based on the synchronization timing information. After synchronization, the access point can know what the measurement window corresponding to the frame time information report is after receiving the frame time information report transmitted by the station, and thereby the frame time information can be obtained. Based on the report, it can be determined whether there is a hidden terminal for the station.

Among them, the synchronization timing information may be carried by a beacon frame transmitted by the access point, or may be carried by other signaling transmitted by the access point.

As can be seen by the method of the present embodiment, the station sends a frame time information report to the access point to assist in diagnosing the failure or to solve the problem of degraded performance of the CSMA/CA wireless network. You can

The present embodiment further provides a method for identifying a hidden terminal, which is a process on the access point side, which is used for an access point in a CSMA/CA wireless network and corresponds to the method of the first embodiment. The description of the same contents as in the first embodiment is omitted. FIG. 3 is a flow chart of the method, and as shown in FIG. 3, the method includes the following steps.

Step 301: Establish a measurement window of the frame time information report based on the received frame time information report transmitted by the stations in the CSMA/CA wireless network;
Step 302: comparing timing information of each frame in the frame time information report with pre-stored timing information of a frame received within the measurement window;
Step 303: If the received frame has a frame that collides with the frame in the frame time information report, and the collision rate is larger than a predetermined second threshold, the station that has transmitted the collision frame sends the station to the station. Determined to be a hidden terminal for all.

In this embodiment, as in the first embodiment, the frame time information report includes the timing information of the frames transmitted within the measurement window, and may be the timing information of all the frames transmitted within the measurement window. It may well be timing information of a frame that has been received within the measurement window for which an acknowledgment has not been received, and the timing information of the frame may include a transmission time and a duration of the frame. Since it is the same as the first embodiment, detailed description thereof will be omitted here.

In step 301, the access point can synchronize with the station by sending the synchronization timing information to the station, as described above, so that it can respond accordingly based on the frame time information report. The measurement window can be determined, for example, after synchronization, the access point determines in which measurement window the frame is located based on the timing information of the frame included in the frame time information report. Therefore, the measurement window corresponding to the frame time information report can be determined. The access point can also determine the measurement window corresponding to the frame time information report by using the measurement window instruction information in the frame time information report. If it is the index of the measurement window, the access point can determine the measurement window corresponding to the frame time information report based on the index of the measurement window, and, for example, information for indicating the measurement window. Is the start time and length of the measurement window, the access point can also determine the measurement window corresponding to the frame time information report based on this information.

In this embodiment, the access point can store the timing information of the frame received or listened to in a predetermined period in advance, and can periodically update or release the stored timing information of the frame. The timing information of the frame may include a frame transmission time, a duration, and a transmission address. Among them, the meanings of the transmission time and the duration are the same as the timing information of the frame in the frame time information report transmitted by the station, but the transmission address refers to the address of the station transmitting the frame. For example, the access point previously stores timing information of a frame for 10 seconds, and within the 10 seconds, the access point transmits four frames transmitted by three stations STA1, STA2 and STA3, that is, 1 transmitted by STA1. When receiving or listening to one frame A, two frames B and C transmitted by STA2, and one frame D transmitted by STA3, the timing information of the frames stored by the access point is The transmission time and duration and the address of STA1, the transmission time and duration of each of B and C and the address of STA2, the transmission time and duration of D and the address of STA3.

In step 302, if there is timing information of each frame in the frame time information report and timing information of each frame of the measurement window corresponding to the frame time information report stored in advance, the access point compares them. This makes it possible to determine whether or not the received frame includes a frame that collides with the frame in the frame time information.

In step 303, if there is a frame in the received frame that collides with the frame in the frame time information report, and if the collision rate is greater than one threshold value (referred to as the second threshold value in this embodiment), the collision occurs. It is determined that the station that has transmitted the frame is a hidden terminal for the station that has transmitted the frame time information report.

In this embodiment, the received frame collides with the frame in the frame time information report based on the timing information of the frame in the frame time information report and the stored timing information of the frame (also referred to as a collision frame). ) Can be established. If any one of the following conditions is satisfied, it is determined that the received frame collides with the frame in the frame time information report.

Condition 1: t _j ≤T _i ≤t _j +d _j ≤T _i +D _i and t _j +d _j -T _i ≥GT, that is, the received i-th frame is the frame time. Although it is behind in time with respect to the j-th frame in the information report, both of them partially overlap and the overlapping portion is larger than the protection time.

Condition 2: T _i ≤t _j ≤T _i +D _i ≤t _j +d _j and T _i +D _i -t _j ≥GT, that is, the received i-th frame is the frame time. Although it is ahead in time with respect to the j-th frame in the information report, both of them partially overlap and the overlapping portion is larger than the protection time.

Condition 3: t _j ≤T _i ≤T _i +D _i ≤t _j +d _j , that is, the received i-th frame is completely covered by the j-th frame in the frame time information report. Be seen.

Condition 4: T _i ≤t _j ≤t _j +d _j ≤T _i +D _i, that is, the j-th frame in the frame time information report is completely covered by the i-th frame that has been received. Be seen.

Among them, t _j is the transmission time of the j-th frame in the frame time information report, T _i is the transmission time of the received i-th frame, and d _j is the frame time information report. Is the duration of the j-th frame in the frame, D _i is the duration of the received i-th frame, and GT is the preset protection time.

FIG. 4 is a diagram showing an example of comparing the stored frame timing information with the frame timing information in the frame time information report. As shown in FIG. 4, in the example, the station transmitting the frame time information report is STA1, the measurement window corresponding to the frame time information report is w, and the measurement window w in the frame time information report is w. There is timing information of three frames STA1-1, STA1-2 and STA1-3 corresponding to the above; the access point previously stores timing information of four frames corresponding to the measurement window w, and these four frames are stored. Are respectively STA-1, STA-2, STA-3 and STA-4, of which STA-1 and STA-4 are those transmitted by STA2, and STA-2 are those transmitted by STA1. Yes, it is assumed that STA-3 is transmitted by STA3.

As shown in FIG. 4, looking at STA1-1 and STA-1, both partially overlap in time, satisfying t ₁ <T ₁ <t ₁ +d ₁ <T ₁ +D ₁ , and, Since the overlapping part is larger than the protection time and t ₁ +d ₁ -T ₁ >GT is satisfied, the above condition 1 is satisfied, and in this case, STA-1 is determined to be a collision frame of STA1-1. be able to.

As shown in FIG. 4, when looking at STA1-2 and STA-2, they completely overlap in time, but because STA1-2 and STA-2 are both transmitted by STA1, that is, , The station STA1 does not need to consider STA-2 because the frame transmitted by itself does not collide with itself.

As shown in Fig. 4, when STA1-3 and STA-3 are seen, they partially overlap in time and satisfy T ₃ <t ₃ <T ₃ +D ₃ <t ₃ +d ₃ , but they overlap. Since the part is below the protection time, that is, T ₃ +D ₃ −t ₃ ≦GT, Condition 2 is not satisfied, and the other 3 conditions are not satisfied either. In this case, STA-3 is not the collision frame of STA1-3.

As shown in FIG. 4, when viewing STA1-3 and STA-4, they partially overlap in time, and satisfy t ₃ <T ₄ <t ₃ +d ₃ <T ₄ +D ₄ , Moreover, since the overlapping portion is longer than the protection time, that is, t ₃ +d ₃ -T ₄ >GT, the above condition 1 is satisfied, and in this case, STA-4 is the collision frame of STA1-3. Can be confirmed.

In the example shown in FIG. 4, by the above determination, it is determined that the received frame has a frame that collides with the frame in the frame time information report, that is, STA-1 and STA-4. In the embodiment, if the collision rate is larger than the second threshold, it is possible to determine that the station STA2 that has transmitted the collision frames STA-1 and STA-4 described above is the hidden terminal of STA1. Among them, the collision rate refers to a ratio of collision frames transmitted by the same station within the measurement window to the total number of frames in the frame time information report. In the example shown in FIG. 4, there are two collision frames in total, and there are three frames in the frame time information report. If the second threshold is 50%, 2/3>50%, so the collision rate is higher than the second threshold, and it can be determined that STA2 is a hidden terminal of STA1. Thereby, the hidden terminal can be identified.

In the present embodiment, the above determination conditions are merely examples, and other determination conditions and methods that use frame timing information also belong to the protection scope of the present invention.

In this embodiment, corresponding to the first embodiment, the method may further include the following steps in order to realize the synchronization of the access point and the station, namely:
Step 300: Transmit synchronization timing information so that the station receiving the synchronization timing information synchronizes the access point with the measurement window based on the synchronization timing information.

Similarly, synchronizing the measurement window means synchronizing the start time and period of the measurement window, or synchronizing the window index of the measurement window, and the synchronization timing information is It may be carried by a beacon frame transmitted by the point or by another signaling transmitted by the access point.

In this embodiment, if a plurality of stations send frame time information reports to the access point and the frame time information reports sent by different stations correspond to the same measurement window, the access point The timing information of each frame in the frame time information report can be added to the timing information of the frame corresponding to the previously stored measurement window. As shown in FIG. 5, when the access point receives the frame time information report corresponding to the measurement windows w of STA1 and STA2, the access point is STA1-1 in the frame time information report of STA1, STA1-2, Timing information of STA1-3, and STA2-1 in the frame time information report of STA2, STA2-2, stores the timing information of STA2-3, together with the timing information of the frame stored in advance, as a reference, this , It is possible to judge whether there is a collision frame, and by this, it is possible to identify whether the hidden terminal of STA1 and the hidden terminal of STA2 exist. In the example of FIG. 5, STA1 is finally determined to be the hidden terminal of STA2, and at the same time, STA2 is also determined to be the hidden terminal of STA1. Note that the determination method is the same as that described above, so a detailed description is omitted here.

As can be seen from the method of the present embodiment, the timing information of the frame in the frame time information report is compared with the timing information of the received frame to determine whether there is a conflicting frame, and Presence can be identified, which can assist in diagnosing failures or solve the problem of degraded performance of CSMA/CA wireless networks.

This embodiment further provides a device for identifying hidden terminals, which device is used for stations in a CSMA/CA wireless network. Since the principle that the device solves the problem is similar to the method of the first embodiment, its specific implementation can refer to the implementation of the method of the first embodiment, and the description having the same contents is omitted. To be done.

FIG. 6 is a block diagram of an apparatus for identifying hidden terminals according to the present embodiment. As shown in FIG. 6, the apparatus 600 includes a statistics unit 601 and a transmission unit 602.

Statistics unit 601: Obtains the ratio of frames that have not received an acknowledgment in the measurement window by statistics;
Sending unit 602: Sending a frame time information report to an access point (AP) in the CSMA/CA wireless network when the ratio is greater than a preset first threshold, and the frame time information report is used for the measurement. It includes the timing information of the frames transmitted in the window, so that the AP determines whether there is a hidden terminal for the station based on the timing information.

Among them, the frames transmitted in the measurement window are all the frames transmitted in the measurement window, or the frames transmitted in the measurement window for which the reception confirmation has not been received.

The timing information of the frame includes a transmission time and a duration of the frame.

In one implementation, the device may further include:
Receiving unit 603: receiving the synchronization timing information transmitted by the access point;
Synchronization unit 604: Synchronizes the access point with the measurement window based on the synchronization timing information.

Among them, the synchronization unit 604 may synchronize the measurement start time and period with the access point, and may synchronize the access point with the window index, thereby synchronizing the measurement window.

Among them, the synchronization timing information may be carried in a beacon frame transmitted by the access point or may be carried in another signaling transmitted by the access point.

Among them, the frame time information report may further include information for indicating the above-mentioned measurement window, for example, the start time and period of the above-mentioned measurement window, or the window index of the above-mentioned measurement window. ..

As can be seen from the apparatus of this embodiment, by transmitting the frame time information report to the access point, it is possible to assist in the diagnosis of failure or solve the problem of degraded performance of the CSMA/CA wireless network.

This embodiment further provides a device for identifying hidden terminals, which device is used for an access point in a CSMA/CA wireless network. Since the principle that the device solves the problem is similar to the method of the second embodiment, its specific implementation can refer to the implementation of the method of the second embodiment, and the description having the same content is omitted. ..

FIG. 7 is a block diagram of an apparatus for identifying a hidden terminal according to the present embodiment. As shown in FIG. 7, the apparatus 700 includes a first confirmation unit 701, a comparison unit 702 and a second confirmation unit 703.

First determining unit 701: determining the measurement window of the frame time information report based on the received frame time information report transmitted by the stations in the CSMA/CA wireless network.

Comparing unit 702: Comparing the timing information of each frame in the frame time information report with the previously stored timing information of the frame received within the measurement window.

Second determining unit 703: When the received frame includes a frame that collides with the frame in the frame time information report, and the collision rate is larger than a second threshold, the station that transmitted the collision frame is transmitted to the station. Determined as a hidden terminal for the other.

Of which, the second determination unit 703 further includes:
First determination module 7031: the received frame is a frame in the frame time information report, based on the timing information of the frame in the frame time information report and the previously stored timing information of the frame corresponding to the above measurement window. Determine whether to collide with;
Second judgment module 7032: When the judgment result of the first judgment module 7031 is “Yes”, it is judged whether the collision rate is higher than the second threshold value;
Determining module 7033: When the determination result of the second determining module 7032 is “Yes”, it determines that the station that transmitted the collision frame is a hidden terminal for the station that transmitted the frame time information report.

Among them, the first determination module 7031 (the second determination unit 703) is configured such that t _j ≤T _i ≤t _j +d _j ≤T _i +D _i and t _j +d _j -T _i ≥GT; or T _i ≤t _j ≤T _i +D _i ≤t _j +d _j , and T _i +D _i -t _j ≥GT; or t _j ≤T _i ≤T _i +D _i ≤t _j +d _j ; Alternatively, when T _i ≤t _j ≤t _j +d _j ≤T _i +D _i , it is determined that the received frame collides with the frame in the frame time information report. Among them, t _j is the transmission time of the j-th frame in the frame time information report, T _i is the transmission time of the received i-th frame, and d _j is the frame time information report. Is the duration of the j-th frame in the frame, D _i is the duration of the received i-th frame, and GT is the preset protection time.

The collision rate refers to a ratio of collision frames transmitted by the same station within the measurement window to the total number of frames in the frame time information report.

In this embodiment, the device 700 may further include:
Sending unit 704: Sending synchronization timing information, whereby the station receiving the synchronization timing information synchronizes the access point with the measurement window based on the synchronization timing information, that is, measurement start time and period. Or the window index is synchronized. Among them, the transmitting unit 704 may transmit the synchronization timing information by a beacon frame transmitted by the access point, or may transmit the synchronization timing information by another signaling transmitted by the access point.

In this embodiment, the device 700 may further include:
Storage unit 705: Stores timing information of a frame received in a predetermined period in advance, and the timing information may include a transmission time (start time) of the frame, a duration, and a transmission address. Optionally, the storage unit 705 may also update or release the timing information of its stored frames to ensure that the timing information of its stored frames is always current.

In this embodiment, the device 700 may further include:
Update unit 706: When the access point receives frame time information reports within the same measurement window from multiple stations, the timing information of each frame in these frame time information reports is stored in advance in the measurement. It is added to the timing information of the frame corresponding to the window to determine whether there is a hidden terminal for the station that sent the frame time information report.

As can be seen from the device of the present embodiment, the presence of hidden terminals can be determined by comparing the timing information of the frames in the frame time information report with the timing information of the received frames and determining the presence of collision frames. It can be identified, which can aid in the diagnosis of failures or solve the problem of degraded performance of CSMA/CA wireless networks.

Embodiments of the present invention further provide a station in a CSMA/CA wireless network, the station including the device for identifying hidden terminals as described in embodiment 3.

FIG. 8 is a block diagram of the station. As shown in FIG. 8, the station 800 may include a central processing unit 801 and a storage unit 802; the storage unit 802 is coupled to the central processing unit 801. It should be noted that the figure is merely an example, in other words, a telecommunication function or other function can be realized by supplementing or substituting for the structure using another type of structure.

In one implementation, the function of the device for identifying hidden terminals can be integrated in the central processing unit 801, that is, the central processing unit 801 realizes the function of the device for identifying hidden terminals described in the third embodiment. However, the function of the device for identifying the hidden terminal may be merged here, and a detailed description thereof will be omitted here.

In another implementation, the device for identifying hidden terminals may be located separately from the central processing unit 801, for example, the device for identifying hidden terminals may be configured as a chip connected to the central processing unit 801. In this case, the function of the device for identifying the hidden terminal can be realized by the control of the central processing unit 801.

As shown in FIG. 8, the station 800 may further include a communication module 803, an input unit 804, a voice processing unit 805, a display 806, and a power supply 807. It should be noted that the station 800 does not necessarily have to include all the components shown in FIG. 8, and the station 800 may further include other components not shown in FIG. 8, for which the prior art can be referred to. ..

As shown in FIG. 8, the central processing unit 801 is sometimes referred to as a controller or operational controller and may include a microprocessor or other processing unit and/or logic unit, which may be an input device. Can be received to control the operation of each part of station 800.

The storage device 802 may be, for example, one or more of a buffer, a flash memory, an HDD, a removable medium, a volatile storage device, a non-volatile storage device, or another suitable device. Information regarding the above-described configuration may be stored, the functions of the above-described storage unit may be realized, and a program for executing the relevant information may be stored. Further, the central processing unit 801 can also execute the program stored in the storage unit 802 to realize storage or processing of information. The functions of the other components are the same as those of the conventional one, and therefore detailed description thereof is omitted here. Also, each component of station 800 may be implemented by dedicated hardware, firmware, software, or a combination thereof, all of which are within the scope of the invention.

As can be seen from the station of the present embodiment, sending the frame time information report to the access point can help diagnose the failure or solve the problem of degraded performance of the CSMA/CA wireless network.

This embodiment further provides an access point in a CSMA/CA wireless network, wherein the access point includes the device for identifying hidden terminals as described in embodiment 4.

FIG. 9 is a block diagram of one implementation method of the access point of this embodiment. As shown in FIG. 9, the access point 900 may include a central processing unit (CPU) 901 and a memory 902; the memory 902 is coupled to the central processing unit 901. Among them, the storage unit 902 may store various kinds of data; and also may store a program for information processing. By executing the program under the control of the central processing unit 901, various information transmitted by the station can be received and various information can be transmitted to the station.

In one implementation, the functionality of the device for identifying hidden terminals may be integrated in the central processing unit 901, in which case the central processing unit 901 may perform the functions of the device for identifying hidden terminals as described in Example 4. Since the function of the device for realizing the hidden terminal is realized here, the detailed description thereof will be omitted here.

In another implementation, the device for identifying hidden terminals may be located separately from the central processing unit 901, for example, the device for identifying hidden terminals may be configured as a chip connected to the central processing unit 901. In this case, the function of the device for identifying the hidden terminal can be realized by the control of the central processing unit 901.

Further, as shown in FIG. 9, the access point 900 may further include a transceiver 903, an antenna 904, and the like; of which, since the functions of the above-described components are the same as those in the conventional art, a detailed description thereof will be omitted here. .. It should be noted that the access point 900 does not necessarily have to have all the components shown in FIG. 9, and the access point 900 may further include components not shown in FIG. 9, for which the prior art can be referred to. ..

As can be seen from the access point of this embodiment, by comparing the timing information of the frame in the frame time information report and the timing information of the received frame and determining whether there is a collision frame, the hidden terminal Can be identified, which can assist in diagnosing the fault or solve the problem of degraded performance of the CSMA/CA wireless network.

The present embodiment further provides a CSMA/CA wireless network system, FIG. 10 is a topological structural diagram of the system, and as shown in FIG. 10, the system 1000 includes a station 1001 and an access point 1002.

Among them, the station 1001 is configured as follows:
Acquire statistically the ratio of frames that have not received an acknowledgment within the measurement window;
If the ratio is greater than a preset first threshold, it sends a frame time information report to the access point (AP), the frame time information report is an index of the measurement window, and within the measurement window. The timing information of the transmitted frame is included, so that the access point determines whether there is a hidden terminal for the station based on the timing information.

Of these, the station 1001 can be realized by the station of the fifth embodiment, and since the contents thereof are merged here, detailed description thereof will be omitted here.

Among them, the access point 1002 is configured as follows:
Determining a measurement window of the frame time information report based on the received frame time information report of the station;
Comparing timing information for each frame in the frame time information report with pre-stored timing information for frames received within the measurement window;
If the received frame includes a frame that collides with the frame in the frame time information report and the collision rate is larger than the second threshold, the station that transmitted the collision frame is a hidden terminal for the station. To be confirmed.

Of these, the access point 1002 can be realized by the access point of the sixth embodiment, and the contents thereof are merged here, so that the detailed description will be omitted here.

The system of this embodiment can assist in diagnosing faults or solve the problem of degraded performance of CSMA/CA wireless networks.

Embodiments of the present invention further provide a computer-readable program, wherein when executing the program in a station of a CSMA/CA wireless network, the program is executed by a computer in a station of the CSMA/CA wireless network. Perform the method described in Example 1.

Embodiments of the present invention further provide a storage medium having a computer-readable program stored therein, the computer-readable program causing a computer to perform the method described in embodiment 1 in a station of a CSMA/CA wireless network.

Embodiments of the present invention further provide a computer-readable program, wherein when executing the program in an access point of a CSMA/CA wireless network, the program causes a computer to access the computer in the access point of the CSMA/CA wireless network. The method described in Example 2 is performed.

Embodiments of the present invention further provide a storage medium having a computer-readable program stored therein, the computer-readable program causing a computer to perform the method according to the second embodiment in an access point of a CSMA/CA wireless network. ..

The apparatus and method according to the embodiments of the present invention may be realized by software, hardware, or a combination of hardware and software. The present invention also relates to such a computer-readable program, that is, the program, when executed by a logic component, can cause the logic component to realize the above-described device or component, or The logic component may also implement the method or steps described above. Furthermore, the present invention also relates to a storage medium for storing the above program, for example, a hard disk, a magnetic disk, an optical disk, a DVD, a flash memory.

Further, regarding the implementation method of the above-described embodiment, the following supplementary notes are further disclosed.

(Appendix 1)
A device for identifying hidden terminals,
The device is used for a station in a CSMA/CA wireless network,
A statistical unit for statistically obtaining the ratio of frames for which acknowledgment has not been received within the measurement window; and when the ratio is greater than a preset first threshold value, in the CSMA/CA wireless network A transmission unit for transmitting a frame time information report to an access point (AP), the frame time information report including timing information of a frame transmitted within the measurement window, whereby the AP is An apparatus comprising a transmitting unit for determining whether a hidden terminal exists for the station based on timing information.

(Appendix 2)
The device according to appendix 1,
The frame transmitted in the measurement window is
An apparatus, which is all the frames transmitted in the measurement window, or the frames transmitted in the measurement window for which a reception confirmation has not been received.

(Appendix 3)
The device according to appendix 1,
The apparatus of claim 1, wherein the frame timing information includes a transmission time (start time) and a duration (duration) of the frame.

(Appendix 4)
The device according to Appendix 1, further comprising:
An apparatus comprising: a receiving unit for receiving the synchronization timing information transmitted by the access point; and a synchronization unit for synchronizing the access point and the measurement window based on the synchronization timing information.

(Appendix 5)
The device according to attachment 4,
The synchronization unit synchronizes a measurement start time and a period, or synchronizes a window index.

(Appendix 6)
The device according to attachment 4,
An apparatus wherein the synchronization timing information is carried in a beacon frame transmitted by the access point or by other signaling transmitted by the access point.

(Appendix 7)
The device according to appendix 1,
The apparatus of claim 1, wherein the frame time information report further includes information for indicating the measurement window.

(Appendix 8)
The device according to appendix 7,
The apparatus for instructing the measurement window, the start time and period of the window, or the index of the measurement window.

(Appendix 9)
A device for identifying hidden terminals,
The device is used for an access point in a CSMA/CA wireless network,
A first determining unit for determining a measurement window of the frame time information report based on a received frame time information report transmitted by a station in the CSMA/CA wireless network;
A comparison unit for comparing the timing information of each frame in the frame time information report with the pre-stored timing information of the frame received in the measurement window; and the frame time information report for the received frame. A second determining unit for determining that the station that transmitted the collision frame is a hidden terminal for the station when there is a frame that collides with the inner frame and the collision rate is larger than a second threshold. Including a device.

(Appendix 10)
The device according to attachment 9,
The second confirmation unit is
Whether the received frame collides with the frame in the frame time information report based on the timing information of the frame in the frame time information report and the timing information of the frame stored in advance corresponding to the measurement window. First judgment module for judging;
A second judgment module for judging whether the collision rate is larger than a second threshold value when the judgment result of the first judgment module is "yes"; and when the judgment result of the second judgment module is "yes" An apparatus comprising a confirmation module for determining that the station that transmitted the collision frame is a hidden terminal for the station that transmitted the frame time information report.

(Appendix 11)
The device according to appendix 10,
The first judgment module,
t _j ≤T _i ≤t _j +d _j ≤T _i +D _i , and t _j +d _j -T _i ≥GT; or
T _i ≤t _j ≤T _i +D _i ≤t _j +d _j , and T _i +D _i -t _j ≥GT; or
t _j ≤T _i ≤T _i +D _i ≤t _j +d _j ; or
T _i ≤t _j ≤t _j +d _j ≤T _i +D _i
At the time, it is determined that the i-th frame received collides with the j-th frame in the frame time information report,
Among them, t _j is the transmission time of the j-th frame in the frame time information report, T _i is the transmission time of the received i-th frame, and d _j is the frame time. The device is the duration of the j-th frame in the information report, D _i is the duration of the i-th frame received, and GT is the preset guard time.

(Appendix 12)
The device according to appendix 10,
The apparatus, wherein the collision rate is a ratio of collision frames transmitted by the same station in the measurement window to the total number of frames in the frame time information report.

(Appendix 13)
The device according to attachment 9, further comprising:
An apparatus comprising a transmitting unit for transmitting synchronization timing information, whereby a station receiving the synchronization timing information synchronizes the access point with a measurement window based on the synchronization timing information.

(Appendix 14)
The device according to attachment 13,
The transmitting unit transmits the synchronization timing information by a beacon frame transmitted by the access point, or transmits the synchronization timing information by another signaling transmitted by the access point.

(Appendix 15)
The device according to attachment 9, further comprising:
A storage unit for storing the timing information of the received frame in advance,
The apparatus according to claim 1, wherein the timing information includes a start time, a duration, and a transmission address of the frame.

(Appendix 16)
The device according to attachment 9, further comprising:
When the access point receives the frame time information reports of a plurality of stations in the same measurement window, the timing information of each frame in these frame time information reports is stored in advance in a frame corresponding to the measurement window. An apparatus including an updating unit for adding to the timing information of the apparatus.

(Appendix 17)
A CSMA/CA wireless network system,
Including stations and access points,
The station is
Acquire statistically the ratio of frames that have not received an acknowledgment within the measurement window; and report frame time information to the access point (AP) when the ratio is greater than a preset first threshold. And the frame time information report includes an index of the measurement window and timing information of a frame transmitted in the measurement window, whereby the access point is configured to transmit the station based on the timing information. Is configured to determine if there is a hidden terminal for
The access point is
Determining a measurement window of the frame time information report based on the received frame time information report of the station;
The timing information of each frame in the frame time information report is compared with the pre-stored timing information of the frame received in the measurement window; and the received frame is the frame in the frame time information report. A system configured to determine that a station that transmitted a collision frame is a hidden terminal for the station when there is a collision frame and the collision rate is greater than a second threshold.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and all modifications to the present invention are within the technical scope of the present invention without departing from the spirit of the present invention.

Claims (8)

A device for identifying hidden terminals,
The device is used for an access point in a CSMA/CA wireless network,
A first determining unit for determining a measurement window of the frame time information report based on a received frame time information report transmitted by a station in the CSMA/CA wireless network;
A comparison unit for comparing the timing information of each frame in the frame time information report with the previously stored timing information of the frame received in the measurement window, the received frame being transmitted by a station. A comparison unit, which has been
When there is a collision frame that collides with the frame in the frame time information report in the received frames, and the collision rate of the station that has transmitted the collision frame is larger than a predetermined second threshold value, the collision occurs. A second determining unit for determining that the station that has transmitted a frame is a hidden terminal for the station that has transmitted the frame time information report; and When receiving a plurality of frame time information report in, to add the timing information of each frame of the plurality of frame time information report to the pre-stored timing information of the frame corresponding to the measurement window A device, including an update unit. The device according to claim 1 , wherein
The second confirmation unit is
The received frame collides with the frame in the frame time information report based on the timing information of the frame in the frame time information report and the pre-stored timing information of the frame corresponding to the measurement window. A first determining module for determining whether there is a frame, the received frame being transmitted by a station;
A second judgment module for judging whether the collision rate of the station that has transmitted the collision frame is greater than a predetermined second threshold value when the judgment result of the first judgment module is “yes”; and (Ii) When the judgment result of the judgment module is “Yes”, a station for transmitting the collision frame to the station for transmitting the frame time information report is confirmed by a confirmation module for confirming that the station is a hidden terminal. Including, device. The device according to claim 2 , wherein
The first judgment module,
t _j ≤T _i ≤t _j +d _j ≤T _i +D _i , and t _j +d _j -T _i ≥GT; or
T _i ≤t _j ≤T _i +D _i ≤t _j +d _j , and T _i +D _i -t _j ≥GT; or
t _j ≤T _i ≤T _i +D _i ≤t _j +d _j ; or
T _i ≤t _j ≤t _j +d _j ≤T _i +D _i
When, the received i-th frame is determined to collide with the j-th frame in the frame time information report,
t _j is the transmission time of the j-th frame in the frame time information report, T _i is the transmission time of the received i-th frame, and d _j is the frame time information report The device is the duration of the j-th frame in the device, D _i is the duration of the i-th frame received, and GT is the preset protection time. The device according to claim 2 , wherein
The apparatus, wherein the collision rate is a ratio of collision frames transmitted by the same station in the measurement window to the total number of frames in the frame time information report. The device of claim 1 , further comprising:
An apparatus comprising a transmitting unit for transmitting synchronization timing information, whereby a station receiving the synchronization timing information synchronizes the access point with the measurement window based on the synchronization timing information. The apparatus according to claim 5 , wherein the transmission unit transmits the synchronization timing information in a beacon frame transmitted by the access point, or the synchronization timing information according to other signaling transmitted by the access point. Device to send. The device of claim 1 , further comprising:
A storage unit for storing the timing information of the received frame in advance,
The apparatus according to claim 1, wherein the timing information includes a start time, a duration, and a transmission address of the frame. A CSMA/CA wireless network system,
Including stations and access points,
The station is
Acquire statistically the ratio of frames that have not received an acknowledgment in the measurement window; and send a frame time information report to the access point (AP) when the ratio is greater than a predetermined first threshold However, the frame time information report includes an index of the measurement window and timing information of a frame transmitted in the measurement window, whereby the access point notifies the station based on the timing information. Configured to determine if there are hidden terminals in
The access point is
Establish a measurement window of the frame time information report based on the received frame time information report sent by the station;
Comparing timing information for each frame in the frame time information report with pre-stored timing information for a frame received in the measurement window, the received frame being transmitted by a station; and When there is a collision frame that collides with the frame in the frame time information report in the received frames, and the collision rate of the station that has transmitted the collision frame is larger than a predetermined second threshold value, the collision occurs. A CSMA/CA wireless network system configured to determine that the station that sent a frame is a hidden terminal for the station that sent the frame time information report.

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