CN107241763A

CN107241763A - Probe response method and device

Info

Publication number: CN107241763A
Application number: CN201610188707.9A
Authority: CN
Inventors: 张�林; 欧历云
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2016-03-29
Filing date: 2016-03-29
Publication date: 2017-10-10
Anticipated expiration: 2036-03-29
Also published as: CN107241763B; WO2017167140A1

Abstract

A kind of probe response method and device, is related to communication technical field, and this method includes：The probe request that receiving terminal is sent；Probing response frame is generated according to the probe request；The random waiting time for determining to send the probing response frame, overtime duration of the waiting time no more than probing response frames to be received such as the terminals；Begun to pass through from the probe request is received after the waiting time, the probing response frame is sent to the terminal, because each wireless aps each determine waiting time at random, therefore, the possibility that multiple wireless aps send probing response frame simultaneously is low, so as to improve the success rate of probing response frame transmission, wireless medium resource is saved.

Description

Probe response method and device

Technical Field

The present invention relates to the field of communications technologies, and in particular, to a probe response method and apparatus.

Background

In a Wireless Local Area Network (WLAN), a terminal may access a distribution service (english) through an Access Point (AP).

After receiving a probe request frame sent by a terminal to a wireless AP, the wireless AP responds to the probe request frame and returns a probe response frame to the terminal.

When a plurality of wireless APs with the same working channel exist near one terminal, a plurality of probe response frames sent by the plurality of wireless APs collide, thereby causing failure in sending the probe response frames.

Disclosure of Invention

In order to solve the problem that the sending fails due to the collision of a plurality of probe response frames, the application provides a probe response method and a probe response device.

In a first aspect, a probe response method is provided, which includes:

receiving a detection request frame sent by a terminal; generating a probe response frame according to the probe request frame; randomly determining the waiting time for sending the detection response frame, wherein the waiting time does not exceed the overtime time for the terminal to wait for receiving the detection response frame; and after the waiting time length elapses from the reception of the probe request frame, transmitting a probe response frame to the terminal.

Because each wireless AP randomly determines the waiting time, the probability that a plurality of wireless APs simultaneously transmit the probe response frame is low, the success rate of transmitting the probe response frame is improved, and wireless medium resources are saved. In a first implementation of the first aspect, randomly determining a waiting duration for sending a probe response frame includes:

acquiring the signal intensity of a detection request frame; determining a waiting window according to the signal strength parameter; and randomly determining the waiting time length for sending the probe response frame from the waiting window, wherein one or more of the window length of the waiting window and the starting time of the waiting window is in a negative correlation relationship with the signal strength parameter.

Because one or more of the window length of the waiting window and the starting time of the waiting window are in a negative correlation relationship with the signal strength parameter, the probability that the value selected from the waiting window corresponding to the signal strength parameter with a large value is smaller than the value selected from the waiting window corresponding to the signal strength parameter with a small value is high, so that the probability that the waiting time length determined by the wireless AP with strong signal strength is shorter than the waiting time length determined by the wireless AP with weak signal strength is improved. The probability that the terminal preferentially receives the detection response frame sent by the wireless AP with strong signal strength is high, and the probability that the terminal accesses the wireless AP with strong signal strength is improved.

With reference to the first implementation of the first aspect, in a second implementation of the first aspect, the determining a waiting window according to a signal strength parameter includes:

searching a waiting window corresponding to the signal strength parameter from a preset window mapping, wherein the window mapping is the mapping from a signal strength parameter set to a window set, and when the starting time is unchanged, the window lengths of a plurality of waiting windows in the window set in the window mapping and a plurality of signal strength parameters in the signal strength parameter set are in a negative correlation relationship; or when the window length is not changed, the starting time of a plurality of waiting windows in the window set in the window map and a plurality of signal strength parameters in the signal strength parameter set are in a negative correlation relationship; or, there is a negative correlation between the start time of the multiple waiting windows in the window set in the window map and the multiple signal strength parameters in the signal strength parameter set, and there is a negative correlation between the window length of the multiple waiting windows in the window set in the window map and the multiple signal strength parameters in the signal strength parameter set.

It should be noted that the window mapping may be a mapping from a signal strength interval to a plurality of waiting windows, to which a plurality of signal strength parameters belong in a signal strength parameter set, and each signal strength interval is not overlapped with each other, at this time, the wireless AP may uniquely determine the signal strength interval corresponding to the signal strength parameter, and determine the waiting window according to the signal strength interval, thereby avoiding a waiting window corresponding to the signal strength parameter of the current probe request frame in the window mapping, so that the wireless AP cannot find the waiting window corresponding to the signal strength parameter, and thus improving a success rate of finding the waiting window corresponding to the signal strength parameter.

With reference to the first implementation of the first aspect or the second implementation of the first aspect, in a third implementation of the first aspect, the obtaining a signal strength parameter of the probe request frame includes:

measuring a signal strength indicator (RSSI) of the probe request frame, and using the RSSI as a signal strength parameter of the probe request frame; or,

detecting whether the interval between the receiving time of the previous detection request frame and the receiving time of the detection request frame exceeds a preset time length, measuring the RSSI of the detection request frame when the interval is determined not to exceed the preset time length, acquiring the signal strength parameter of the previous detection request frame, carrying out weighted average on the value of the RSSI and the value of the signal strength parameter of the previous detection request frame, and taking the result of the weighted average as the signal strength parameter of the detection request frame.

When the signal strength of the probe request frame fluctuates, the accuracy of acquiring the signal strength parameter of the probe request frame can be improved by performing weighted average on the RSSI value of the probe request frame and the signal strength parameter of the previous probe request frame and taking the result of the weighted average as the signal strength parameter of the probe request frame; in addition, when the interval between the receiving time of the previous probe request frame and the receiving time of the probe request frame does not exceed the preset time length, the signal strength parameter is obtained by using the weighted average, so that the problem that the calculated signal strength parameter is inaccurate because the signal strength parameter of the probe request frame is still calculated by using the previous probe request frame when the previous probe request frame cannot reflect the signal strength parameter of the probe request frame due to too long interval can be avoided, and the accuracy of obtaining the signal strength parameter of the probe request frame is further improved.

With reference to the first aspect and any one of the first to third implementations of the first aspect, in a fourth implementation of the first aspect, after the sending the probe response frame to the terminal, the method further includes:

when the sending of the detection response frame fails, determining the maximum retransmission times of the detection response frame according to the signal strength parameter of the detection request frame; and retransmitting the probe response frame according to the maximum retransmission times, wherein the maximum retransmission times and the signal strength parameter have positive correlation.

The maximum retransmission times are randomly determined by each wireless AP, and the maximum retransmission times and the signal strength parameter are in positive correlation, namely the maximum retransmission times corresponding to the wireless AP with weak signal strength are small, and the maximum retransmission times corresponding to the wireless AP with strong signal strength are large, so that when the retransmission times of the wireless AP with weak signal strength reach the maximum retransmission times of the wireless AP, the retransmission times of the wireless AP with strong signal strength do not reach the maximum retransmission times of the wireless AP, and the probe response frame can be continuously retransmitted, thereby improving the probability that the terminal accesses the wireless AP with strong signal strength.

With reference to the fourth implementation of the first aspect, in a fifth implementation of the first aspect, retransmitting the probe response frame according to the maximum retransmission number includes:

randomly determining the waiting time length of a retransmission detection response frame from a waiting window determined according to the signal strength parameter of the detection request frame, wherein at least one of the window length of the waiting window and the starting time of the waiting window is in a negative correlation relation with the signal strength parameter; retransmitting the detection response frame to the terminal when waiting for the waiting time length; when the retransmission of the detection response frame fails, adding 1 to the retransmission times to obtain updated retransmission times; and when the updated retransmission times are less than the maximum retransmission times, continuing to execute the step of randomly determining the waiting duration of the retransmission detection response frame in the waiting window until the retransmission of the detection response frame is successful.

With reference to the first aspect or any one of the first to fifth implementations of the first aspect, in a sixth implementation of the first aspect, if the wireless AP senses that another wireless AP sends another probe response frame to the terminal before sending the probe response frame to the terminal, and the another probe response frame is a response to the probe request frame, the wireless AP ignores sending the probe response frame to the terminal.

When one wireless AP transmits a probe response frame to the terminal, the probe response frame may be sensed by other wireless APs that do not transmit the probe response frame. The wireless AP listens to the probe response frame of another wireless AP, which indicates that there is no other probe response frame colliding with the probe response frame at this time, otherwise the wireless AP cannot listen to the probe response frame due to collision of multiple probe response frames. The transmission success rate of the probe response frame to be sensed is high. Therefore, the wireless AP which does not transmit the probe response frame does not need to transmit its own probe response frame to the terminal. The wireless AP with longer waiting time does not send a detection response frame to the terminal no matter whether the waiting time is passed or not from the time when the wireless AP receives the detection request frame to the time when the wireless AP receives the detection request frame next time, thereby saving wireless medium resources.

In a second aspect, a probe response apparatus is provided, which includes at least one unit configured to implement the probe response method provided in the first aspect or at least one implementation of the first aspect.

In a third aspect, a wireless AP is provided, the apparatus comprising: the wireless transceiver is connected with the processor;

the wireless transceiver is configured to be controlled by a processor for implementing the probe response method provided in the first aspect or at least one implementation of the first aspect.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of a communication system according to an exemplary embodiment of the present invention;

fig. 2 is a schematic structural diagram of a wireless AP according to an exemplary embodiment of the present invention;

FIG. 3 is a flow chart of a probe response method provided by an exemplary embodiment of the present invention;

fig. 4 is a block diagram of a probe response device according to an exemplary embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Reference herein to "a unit" is to a logically partitioned functional structure, and the "unit" may be implemented by pure hardware or a combination of hardware and software.

Referring to fig. 1, a schematic structural diagram of a communication system 100 according to an exemplary embodiment of the present invention is shown. The communication system 100 includes a terminal 120 and a plurality of wireless APs 140.

Since the probe response frames transmitted on different operating channels do not collide, the neighboring wireless AP140 may select different operating channels. For example, the adjacent 3 wireless APs are wireless AP1, wireless AP2 and wireless AP3, the operating channel of the wireless AP1 is 1, the operating channel of the wireless AP2 is 6 and the operating channel of the wireless AP3 is 11.

However, in a place where the flow of people is large, such as a mall, a station, and the like, the wireless APs 140 are deployed at high density. Due to the high deployment density of the wireless APs 140, even if different operating channels are selected for the neighboring wireless APs 140, the operating channels of the wireless APs 140 with overlapping signal coverage areas are the same. The probe response frames sent by the plurality of wireless APs 140 to the terminal may collide, thereby causing the failure of sending the probe response frames.

The terminal 120 may be a mobile phone (english: cellphone), a smart phone (english: smartphone), a computer (english: computer), a tablet computer (english: tablet computer), a wearable device (english: wearable device), a personal digital assistant (english: Personal Digital Assistant (PDA)), a Mobile Internet Device (MID), an e-book reader (english: e-book reader), and the like.

Referring to fig. 2, a schematic structural diagram of a wireless AP200 according to another exemplary embodiment of the present invention is shown. The wireless AP200 may be the wireless AP140 shown in fig. 1, which includes: a processor 220, and a wireless transceiver 240 coupled to the processor 220.

The wireless transceiver 240 may be comprised of one or more antennas that enable the wireless AP200 to send or receive radio signals.

The wireless transceiver 240 may be connected to a communication circuit 260, and the communication circuit 260 may perform various processing on signals received via the wireless transceiver 240 or transmitted via the wireless transceiver 240, such as: the communication circuit 260 may be composed of a Radio Frequency (RF) chip and a baseband chip when practical, for modulating a signal transmitted through the wireless transceiver 240 and demodulating a signal received through the wireless transceiver 240.

The communication circuit 260 may be connected to the processor 220. Alternatively, the communication circuit 260 may be integrated in the processor 220. The processor 220 is a control center of the wireless AP, and the processor 220 may be a Central Processing Unit (CPU), a Network Processor (NP), or a combination of the CPU and the NP. The processor 220 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a Programmable Logic Device (PLD), or a combination thereof. The PLD may be a Complex Programmable Logic Device (CPLD), a field-programmable gate array (FPGA), a General Array Logic (GAL), or any combination thereof.

The memory 280 is connected to the processor 220 by a bus or other means, and the memory 280 may be a volatile memory (or a nonvolatile memory), a non-volatile memory (or a combination thereof). The volatile memory may be a random-access memory (RAM), such as a Static Random Access Memory (SRAM) or a Dynamic Random Access Memory (DRAM). The nonvolatile memory may be a Read Only Memory (ROM), such as a Programmable Read Only Memory (PROM), an Erasable Programmable Read Only Memory (EPROM), and an Electrically Erasable Programmable Read Only Memory (EEPROM). The non-volatile memory may also be a flash memory, a magnetic memory, such as a magnetic tape, a floppy disk, or a hard disk. The non-volatile memory may also be an optical disc.

The memory 280 may store a window map. Alternatively, the memory 280 may store the waiting time for sending the probe response frame, the waiting time for retransmitting the probe response frame, and the like, which are determined by the processor 220, and the determination process can be described in step 303 and step 304 below.

Referring to fig. 3, a flowchart of a probe response method according to an exemplary embodiment of the present invention is shown. The present embodiment is exemplified by the method used in the communication system shown in fig. 1, and the method includes the following steps executed by the wireless AP:

step 301, the wireless AP receives a probe request frame sent by the terminal.

The terminal sends out a probe request frame to enable the terminal to discover wireless APs nearby the terminal. The probe request frame at least includes a Service Set Identifier (SSID) and capability information. The value of the SSID may be a specific SSID searched by the terminal or may be a wildcard SSID, i.e., the SSID field is empty. The capability information may be supported rates of the terminal.

Step 302, the wireless AP generates a probe response frame according to the probe request frame.

After receiving the probe request frame, the wireless AP analyzes the probe request frame to detect whether the SSID, the capability information, and the like carried in the probe request frame are matched with its own information, and whether the terminal is allowed to access. When the wireless AP detects that the SSID, capability information, etc. matches its own information and allows the terminal to access, a probe response frame is generated.

Step 303, the wireless AP randomly determines a waiting duration for sending the probe response frame, where the waiting duration does not exceed a timeout duration for the terminal to wait for receiving the probe response frame.

Step 304, the wireless AP sends a probe response frame to the terminal when waiting for the waiting duration.

And the wireless AP monitors the occupation condition of the channel after receiving the detection request frame and before sending the detection response frame. Deferring transmission of the probe response frame if the channel is occupied. Therefore, the waiting time lengths are randomly determined by the plurality of wireless APs respectively, the wireless AP with the shortest waiting time length preferentially occupies the channel, and the other wireless APs delay the sending of the detection response frame, so that the collision can be avoided. A collision will only occur if two wireless APs happen to determine the same latency. Compared with the scheme of immediately sending the detection response frame after receiving the detection response frame, the embodiment of the invention can reduce the probability of the collision of the detection response frames sent by a plurality of wireless APs.

Specifically, the randomly determining the waiting duration for sending the probe response frame includes: acquiring a signal intensity parameter of a detection request frame; determining a waiting window according to the signal strength parameter; and randomly determining the waiting time length for sending the probe response frame from the waiting window. Wherein at least one of the window length of the waiting window and the starting time of the waiting window is in a negative correlation with the signal strength parameter.

Because the waiting window is a value interval, and each wireless AP randomly determines a value from the waiting window as the waiting time, the probability that different wireless APs determine the same value from the value interval included in the waiting window as the waiting time is small, and the probability that the waiting times determined by the wireless APs are the same is reduced, so that the situation that the detection response frames are collided due to the fact that a plurality of wireless APs simultaneously send the detection response frames is avoided. The maximum value of the waiting windows does not exceed the timeout duration of the terminal waiting for receiving the probe response frame, and the waiting windows may or may not overlap with each other, which is not limited in this embodiment.

The wireless AP may determine the wait duration completely randomly. Because each wireless AP randomly determines the waiting time, the collision probability of the detection response frame can be reduced, thereby improving the success rate of sending the detection response frame and saving wireless medium resources.

If the wireless AP can completely randomly determine the waiting duration, the waiting duration determined by the wireless AP is independent of the signal strength of the probe request frame received by the wireless AP. If the waiting time duration determined by the wireless AP with strong signal strength of the received probe request frame is longer than the waiting time duration determined by the wireless AP with weak signal strength of the received probe request frame, the wireless AP with weak signal strength of the received probe request frame may send the probe response frame to the terminal first. The terminal generally selects a wireless AP corresponding to the probe response frame received first. Therefore, the terminal may associate a wireless AP that receives a probe request frame with weak signal strength. If the signal strength of the frame sent by the terminal and received by the wireless AP is strong, the signal strength of the frame sent by the terminal and received by the wireless AP will also be strong, that is, the wireless AP is a wireless AP with strong signal strength for the terminal. Therefore, the terminal may associate a wireless AP with weak signal strength. For convenience of description, in the present embodiment, the signal strength of the wireless AP is represented by the signal strength of the probe request frame received by the wireless AP.

In order to reduce the probability of the above situation, in this embodiment, the wireless AP determines the waiting time for sending the probe response frame according to the signal strength parameter of the received probe request frame and the negative correlation between the waiting time and the signal strength parameter.

When acquiring the signal strength parameter of the probe request frame, one possible implementation manner is to measure the RSSI of the probe request frame, and use the value of the RSSI as the signal strength parameter of the probe request frame.

If the wireless AP randomly determines the waiting duration only according to the signal strength parameter of the currently received probe request frame, in a possible implementation scenario, due to interference between working channels, the value of the signal strength parameter of the probe request frame received by the wireless AP fluctuates up and down, and thus the measured value of the signal strength parameter is inaccurate, resulting in inaccurate waiting duration determined according to the signal strength parameter.

In order to improve the accuracy of obtaining the signal strength parameter of the probe request frame, when calculating the signal strength of the probe request frame, another possible implementation manner is to detect whether the interval between the receiving time of the previous probe request frame and the receiving time of the probe request frame exceeds a preset time length, measure the RSSI of the probe request frame and obtain the signal strength parameter of the previous probe request frame when the interval is determined not to exceed the preset time length, perform weighted average on the value of the RSSI and the value of the signal strength parameter of the previous probe request frame, and take the result of the weighted average as the signal strength parameter of the probe request frame; and when detecting that the interval between the receiving time of the previous probe request frame and the receiving time of the probe request frame exceeds the preset time length, taking the RSSI value of the probe request frame as the signal strength parameter of the probe request frame.

In this implementation, in addition to improving the accuracy of the acquired signal strength parameter by performing weighted average on the RSSI value and the signal strength parameter value of the previous probe request frame, the signal strength parameter is acquired by using weighted average when the interval between the receiving time of the previous probe request frame and the receiving time of the probe request frame does not exceed the preset time length, so that the problem that the calculated signal strength parameter is inaccurate because the signal strength parameter of the probe request frame is still calculated by using the previous probe request frame when the previous probe request frame cannot embody the signal strength parameter of the probe request frame due to too long interval can be avoided, and the accuracy of acquiring the signal strength parameter of the probe request frame is further improved.

The weighted average algorithm may be: the signal strength parameter of the probe request frame is K × RSSI _ NEW + (1-K) × RSSI _ LAST, where RSSI _ NEW represents an RSSI value of a probe response frame currently received by the wireless AP, RSSI _ LAST represents a signal strength parameter value of a previous probe request frame, K is a preset coefficient greater than 0 and less than 1, for example, a value of K may be 0.8, and a value of K and a value of a preset duration are not limited in this embodiment.

When the wireless AP randomly determines the waiting time for sending the probe response frame, determining a waiting window according to the signal strength parameter, wherein the waiting window comprises the following steps: and searching a waiting window corresponding to the signal strength parameter from a preset window mapping, wherein the window mapping is the mapping from a signal strength parameter set to a window set.

In a possible implementation manner, window mapping from each signal strength parameter in the signal strength parameter set to a waiting window in the window set is preset in the wireless AP, and the wireless AP determines the corresponding waiting window according to the obtained signal strength parameter. In this implementation, the wireless AP needs to store a large amount of data of the signal strength parameter and the waiting window, which results in a large amount of memory space occupied by the data. In addition, if the mapping from the acquired signal strength parameter to the waiting window is not recorded in the preset window mapping, the wireless AP cannot determine the waiting window.

In order to solve the above problem, in another possible implementation manner, a signal strength interval corresponding to each signal strength parameter in a preset signal strength parameter set in the wireless AP is mapped to a window of a waiting window in a window set, and the signal strength intervals are not overlapped with each other, and a corresponding waiting window is determined by selecting the signal strength interval corresponding to the signal strength parameter. In this implementation, the wireless AP only needs to store a small amount of data, and each signal strength parameter uniquely corresponds to one signal strength interval.

The present embodiment provides three expression modes of a window set:

first, when the starting time is not changed, the window lengths of a plurality of waiting windows in a window set in the window mapping and a plurality of signal strength parameters in a signal strength parameter set are in a negative correlation relationship.

If the starting time of the two waiting windows is the same, and the window lengths of the two waiting windows are in a negative correlation relation with the signal strength parameter, the wireless AP with strong signal strength determines a value in the waiting window with short window length, and the wireless AP with weak signal strength determines a value in the waiting window with long window length. The longer the window length of the waiting window is, the smaller the probability that the wireless AP determines a certain value is, so that the probability that the value determined by the wireless AP with strong signal strength is smaller than the value determined by the wireless AP with weak signal strength is high, the probability that the waiting time determined by the wireless AP with strong signal strength is smaller than the waiting time determined by the wireless AP with weak signal strength is improved, and the probability that the terminal accesses the wireless AP with strong signal strength is improved.

Assuming that the window mapping is shown in the following table one, if the value of the signal strength parameter of the probe request frame acquired by the first wireless AP is-70 db mw (english: dBm), the corresponding signal strength interval is [ -65dBm, -75dBm ], and the waiting window corresponding to the signal strength interval is [0ms, 6ms ]; the value of the signal strength parameter of the probe request frame acquired by the second wireless AP is-60 dBm, the corresponding signal strength interval is > -65dBm, the waiting window corresponding to the signal strength interval is searched for [0ms, 3ms ], at this time, the first wireless AP determines a numerical value in [0ms, 6ms ], the second wireless AP determines a numerical value in [0ms, 3ms ], and the probability that the numerical value determined by the first wireless AP is greater than the numerical value determined by the second wireless AP is high, so that the probability that the waiting time determined by the second wireless AP is less than the waiting time determined by the first wireless AP is improved.

Table one:

signal strength interval	Waiting window
		＞-65dBm	[0ms，3ms]
[-65dBm，-75dBm]	[0ms，6ms]
		＜-75dBm	[0ms，10ms]

In this embodiment and the following description, only three signal strength sections are set as an example, and in actual implementation, the number of set signal strength sections is not limited in this embodiment.

Secondly, when the window length is not changed, the starting time of a plurality of waiting windows in the window set in the window mapping and a plurality of signal strength parameters in the signal strength parameter set are in a negative correlation relationship.

If the starting time of the two waiting windows and the signal strength parameter are in a negative correlation relationship, and the window lengths of at least two waiting windows are equal, the wireless AP with strong signal strength determines a value in the waiting window with small starting time, and the wireless AP with weak signal strength determines a value in the waiting window with large starting time. Since the window lengths of at least two waiting windows are equal, the larger the starting time of the waiting window, the larger the value included in the waiting window. That is, when the waiting windows do not overlap with each other, the value determined by the wireless AP with weak signal strength is greater than the value determined by the wireless AP with strong signal strength; when the waiting windows are overlapped, the probability that the value determined by the wireless AP with the weak signal strength is larger than the value determined by the wireless AP with the strong signal strength is high, so that the probability that the waiting time length determined by the wireless AP with the strong signal strength is smaller than the waiting time length determined by the wireless AP with the weak signal strength is improved, and the probability that the terminal accesses the wireless AP with the strong signal is improved.

Assuming that the window mapping is as shown in table two below, if the signal strength parameter of the probe request frame acquired by the first wireless AP has a value of-70 dBm, the corresponding signal intensity interval is [ -65dBm, -75dBm ], and the waiting window corresponding to the intensity interval is searched for (3ms, 6ms ]; the value of the signal strength parameter of the probe request frame acquired by the second wireless AP is-60 dBm, the corresponding signal strength interval is > -65dBm, the waiting window corresponding to the signal strength interval is searched for [0ms, 3ms ], at this time, the first wireless AP determines a value in an interval (3ms, 6 ms), the second wireless AP determines a value in an interval [0ms, 3ms ], the value determined by the first wireless AP is greater than the value determined by the second wireless AP, such that the latency period determined by the second wireless AP is less than the latency period determined by the first wireless AP.

Table two:

signal strength	Waiting window
		＞-65dBm	[0ms，3ms]
[-65dBm，-75dBm]	(3ms，6ms]
		＜-75dBm	(6ms，10ms]

Thirdly, there is a negative correlation between the start time of the multiple waiting windows in the window set in the window map and the multiple signal strength parameters in the signal strength parameter set, and there is a negative correlation between the window length of the multiple waiting windows in the window set in the window map and the multiple signal strength parameters in the signal strength parameter set.

Such window mapping may reduce the probability of determining a short latency from a wireless AP with weak signal strength, both in terms of window length and start time.

Assuming that the window mapping is as shown in table three below, if the signal strength parameter of the probe request frame acquired by the first wireless AP has a value of-70 dBm, the corresponding signal intensity interval is [ -65dBm, -75dBm ], and the waiting window corresponding to the intensity interval is searched for (2ms, 5ms ]; the second wireless AP calculates the value of the signal strength parameter of the probe request frame to be-60 dBm, the corresponding signal strength interval is > -65dBm, the waiting window corresponding to the signal strength interval is searched for [0ms, 2ms ], at this time, the first wireless AP determines a value in an interval (2ms, 5 ms), the second wireless AP determines a value in an interval [0ms, 2ms ], the value determined by the first wireless AP is greater than the value determined by the second wireless AP, such that the latency period determined by the second wireless AP is less than the latency period determined by the first wireless AP.

Table three:

signal strength	Waiting window
		＞-65dBm	[0ms，2ms]
[-65dBm，-75dBm]	(2ms，5ms]
		＜-75dBm	(6ms，10ms]

The wireless AP randomly determines the waiting time from the waiting window, which may be implemented by a random algorithm, and this embodiment is not limited.

Although each wireless AP randomly determines the waiting duration from the corresponding waiting window, it is still possible that the waiting durations of two wireless APs are the same. If the two wireless APs send the probe response frame to the terminal at the same time, which results in the failure of sending the probe response frame, the terminal cannot receive the probe response frame, so that a message for confirming the reception is not returned to the wireless APs. At this time, the at least two wireless APs do not receive the acknowledgement message sent by the terminal, so that the probe response frame is informed of the failure of sending the probe response frame, and the probe response frame is retransmitted.

The maximum retransmission times are prestored in each wireless AP, and when a certain wireless AP determines that the sending of the probe response frame fails, the probe response frame is retransmitted until the probe response frame is retransmitted successfully, or until the retransmission times reach the maximum retransmission times, the retransmission times are stopped.

If the time when at least two wireless APs retransmit the probe response frame is the same, the retransmitted probe response frame still fails. And because the maximum retransmission times of all the wireless APs are the same, if none of the wireless APs successfully sends the probe response frame when the retransmission times of all the wireless APs reach the maximum retransmission times, no wireless AP continues to send the probe response frame to the terminal, and at this time, the terminal cannot receive the probe response frame, thereby causing the failure of accessing the terminal to the wireless AP.

In order to solve the above problem, in this embodiment, a retransmission mechanism for a probe response frame is provided, where the retransmission mechanism includes: when the sending of the detection response frame fails, determining the maximum retransmission times of the detection response frame according to the signal strength parameter of the detection request frame, wherein the maximum retransmission times and the signal strength parameter have positive correlation; and retransmitting the detection response frame according to the maximum retransmission times.

Because the maximum retransmission times of the wireless AP with strong signal strength is greater than the maximum retransmission times of the wireless AP with weak signal strength, when the retransmission times of the wireless AP with weak signal strength reaches the maximum retransmission times, the retransmission times of the wireless AP with strong signal strength do not reach the maximum retransmission times, the wireless AP with strong signal strength can continue to retransmit the probe response frame, and the terminal can receive the probe response frame, thereby accessing the wireless AP with strong signal strength.

The signal strength parameter of the probe request frame may be obtained by directly reading the signal strength parameter of the probe request frame acquired in step 303 by the wireless AP.

It should be noted that, when determining the maximum retransmission times according to the signal strength parameter, the wireless AP may determine a signal strength interval corresponding to the signal strength parameter according to a preset time mapping, then search for the maximum retransmission times corresponding to the signal strength interval, and determine the maximum retransmission times corresponding to the signal strength parameter. The selection process of the signal strength interval is the same as the selection process described in step 303, and is not described herein again.

If the number mapping is as shown in the following table four, if the value of the signal strength parameter of the probe request frame acquired by the first wireless AP is-70 dBm, and the corresponding signal strength interval is [ -65dBm, -75dBm ], finding that the maximum retransmission number corresponding to the strength interval is 2; the value of the signal strength parameter of the probe request frame acquired by the second wireless AP is-60 dBm, the corresponding signal strength interval is > -65dBm, the maximum retransmission time corresponding to the signal strength interval is found to be 3, the maximum retransmission time of the second wireless AP is greater than the maximum retransmission time of the first wireless AP, and the probability that the terminal accesses the second wireless AP is improved.

Table four:

signal strength interval	Maximum number of retransmissions
		＞-65dBm	3
[-65dBm，-75dBm]	2
		＜-75dBm	1

After determining the maximum retransmission times, the wireless AP can randomly determine the waiting duration of the retransmission probe response frame from a waiting window determined according to the signal strength parameter of the probe request frame, wherein one or more of the window length of the waiting window and the starting time of the waiting window are in a negative correlation relation with the signal strength parameter; retransmitting the probe response frame to the terminal when waiting for the waiting duration; when the retransmission of the detection response frame fails, adding 1 to the retransmission times to obtain updated retransmission times; and when the updated retransmission times are less than the maximum retransmission times, continuing to execute the step of randomly determining the waiting duration for retransmitting the probe response frame in the slave waiting window until the probe response frame is successfully retransmitted.

The process of determining the waiting duration when retransmitting the probe response frame is the same as the process of determining the waiting duration when transmitting the probe response frame for the first time, which is not described herein again.

And the wireless AP determines a waiting window for retransmitting the detection response frame according to the negative correlation between one or more of the window length of the waiting window and the starting time of the waiting window and the signal strength parameter, and selects a value from the waiting window as the waiting time length. One or more of the window length of the waiting window and the starting time of the waiting window are in a negative correlation relation with the signal strength parameter, so that the probability that the value selected by the wireless AP with strong signal strength is smaller than the value selected by the wireless AP with weak signal strength is high, the probability that the waiting time length determined by the wireless AP with strong signal strength is shorter than the waiting time length determined by the wireless AP with weak signal strength is improved, the probability that the terminal receives the probe response frame retransmitted by the wireless AP with strong signal strength first is high, and the probability that the terminal accesses the wireless AP with strong signal strength is improved.

Assuming that the value of the signal strength parameter of the probe request frame acquired by the wireless AP is-70 dBm, and the corresponding signal strength interval is [ -65dBm, -75dBm ], the window mapping is as shown in table one, the waiting window corresponding to the strength interval is searched for [0ms, 6ms ], and a value is randomly determined from the waiting window as the waiting window.

It should be noted that, in this embodiment, the maximum retransmission number is determined only after the probe response frame is failed to be sent for the first time, and in actual implementation, the wireless AP may also determine the maximum retransmission number when the probe response frame is generated for the first time, which is not limited in this embodiment.

Because the waiting time of the wireless AP with strong signal strength is higher than the waiting time of the wireless AP with weak signal strength, after the multiple wireless APs receive the probe request frame sent by the terminal, the probability that the wireless AP with strong signal strength sends the probe response frame first is high, and when the wireless AP with strong signal strength sends the probe response frame to the terminal, the probe response frame can be listened by other wireless APs which do not send the probe response frame.

When one wireless AP transmits a probe response frame to the terminal, the probe response frame may be sensed by other wireless APs that do not transmit the probe response frame. The wireless AP listens to the probe response frame of another wireless AP, which indicates that there is no other probe response frame colliding with the probe response frame at this time, otherwise the wireless AP cannot listen to the probe response frame due to collision of multiple probe response frames. The transmission success rate of the probe response frame to be sensed is high. If the wireless AP which does not send the probe response frame senses that one wireless AP sends the probe response frame to the terminal, the wireless AP which does not send the probe response frame may ignore sending the probe response frame to the terminal because no other probe response frame which collides with the probe response frame exists at this time and the sending success rate of the probe response frame is high.

The wireless AP which does not send the probe response frame to the terminal no matter whether the waiting time length passes or not from the time when the probe request frame is received to the time when the probe request frame is received next time, thereby saving wireless medium resources.

In summary, in the probe response method provided in the embodiment of the present invention, the waiting duration for sending the probe response frame is randomly determined; and when waiting for the waiting time, sending a detection response frame to the terminal, wherein each wireless AP randomly determines the waiting time, so that the probability of sending the detection response frame by a plurality of wireless APs simultaneously is low, the success rate of sending the detection response frame is improved, and wireless medium resources are saved.

In addition, a waiting window is determined according to the signal strength parameter, the waiting time for sending the probe response frame is randomly determined from the waiting window, and at least one of the window length of the waiting window and the starting time of the waiting window has a negative correlation with the signal strength parameter, so that the probability that the value selected from the waiting window corresponding to the signal strength parameter with a large value is smaller than the value selected from the waiting window corresponding to the signal strength parameter with a small value is high, the probability that the waiting time determined by the wireless AP with a strong signal strength is shorter than the waiting time determined by the wireless AP with a weak signal strength is improved, the probability that the terminal preferentially receives the probe response frame sent by the wireless AP with the strong signal strength is high, and the probability that the terminal accesses the wireless AP with the strong signal strength is improved.

In addition, when the signal strength of the probe request frame fluctuates, the accuracy of acquiring the signal strength parameter of the probe request frame can be improved by performing weighted average on the RSSI value of the probe request frame and the signal strength parameter of the previous probe request frame and taking the result of the weighted average as the signal strength parameter of the probe request frame; in addition, when the interval between the receiving time of the previous probe request frame and the receiving time of the probe request frame does not exceed the preset time length, the signal strength parameter is obtained by using the weighted average, so that the problem that the calculated signal strength parameter is inaccurate because the signal strength parameter of the probe request frame is still calculated by using the previous probe request frame when the previous probe request frame cannot reflect the signal strength parameter of the probe request frame due to too long interval can be avoided, and the accuracy of obtaining the signal strength parameter of the probe request frame is further improved.

In addition, the maximum retransmission times are determined according to the signal strength parameter of the probe request frame, and the maximum retransmission times and the signal strength parameter are in a positive correlation relationship, that is, the maximum retransmission times corresponding to the wireless AP with weak signal strength is small, and the maximum retransmission times corresponding to the wireless AP with strong signal strength is large, so that when the retransmission times of the wireless AP with weak signal strength reach the maximum retransmission times of the wireless AP with weak signal strength, the retransmission times of the wireless AP with strong signal strength do not reach the maximum retransmission times of the wireless AP with strong signal strength, and the probe response frame can be continuously retransmitted, thereby improving the probability that the terminal accesses the wireless AP with strong signal strength.

Referring to fig. 4, a block diagram of a probe response apparatus according to an embodiment of the present invention is shown. The probe response means may be implemented as all or part of the wireless AP by software, hardware, or a combination of both. The probe response apparatus may include: receiving unit 410, generating unit 420, determining unit 430, and transmitting unit 440.

A receiving unit 410, configured to implement the function of step 301.

And a generating unit 420, configured to implement the function of step 302.

A determining unit 430, configured to implement the function of step 303.

A sending unit 440, configured to implement the function of step 304.

The relevant details may be combined with the method embodiment described with reference to fig. 3.

It should be noted that the receiving unit 410 may be implemented by a wireless transceiver in the wireless AP; the generating unit 420 may be implemented by a processor in the wireless AP; the determining unit 430 may be implemented by a processor in the wireless AP; the transmitting unit 440 may determine a transmission timing by a processor in the wireless AP, and is implemented by a wireless transceiver.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation.

It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the apparatuses and units described above may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units may be merely a logical division, and in actual implementation, there may be another division, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

The above description is only for the specific embodiments of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present invention, and all the changes or substitutions should be covered within the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims

1. A probe response method, the method comprising:

receiving a detection request frame sent by a terminal;

generating a detection response frame according to the detection request frame;

randomly determining the waiting time for sending the detection response frame, wherein the waiting time does not exceed the overtime time for the terminal to wait for receiving the detection response frame;

and after the waiting time length is passed since the detection request frame is received, sending the detection response frame to the terminal.

2. The method of claim 1, wherein the randomly determining a waiting duration for transmitting the probe response frame comprises:

acquiring a signal intensity parameter of the detection request frame;

determining a waiting window according to the signal strength parameter, wherein one or more of the window length of the waiting window and the starting time of the waiting window is in a negative correlation relation with the signal strength parameter;

and randomly determining the waiting time length for sending the probe response frame from the waiting window.

3. The method of claim 2, wherein determining a waiting window according to the signal strength parameter comprises:

searching the waiting window corresponding to the signal strength parameter from a preset window mapping, wherein the window mapping is a mapping from a signal strength parameter set to a window set, and when the starting time is unchanged, the window lengths of a plurality of waiting windows in the window set in the window mapping and a plurality of signal strength parameters in the signal strength parameter set are in a negative correlation relationship; or, when the window length is not changed, the starting time of a plurality of waiting windows in the window set in the window map and a plurality of signal strength parameters in the signal strength parameter set are in a negative correlation relationship; or, there is a negative correlation between the start time of the multiple waiting windows in the window set in the window map and the multiple signal strength parameters in the signal strength parameter set, and there is a negative correlation between the window lengths of the multiple waiting windows in the window set in the window map and the multiple signal strength parameters in the signal strength parameter set.

4. The method according to claim 2 or 3, wherein the obtaining the signal strength parameter of the probe request frame comprises:

measuring a signal strength indicator (RSSI) of the probe request frame, and taking the value of the RSSI as a signal strength parameter of the probe request frame; or,

detecting whether the interval between the receiving time of the previous detection request frame and the receiving time of the detection request frame exceeds a preset time length, measuring the RSSI of the detection request frame and acquiring the signal strength parameter of the previous detection request frame when the interval is determined not to exceed the preset time length, carrying out weighted average on the value of the RSSI and the value of the signal strength parameter of the previous detection request frame, and taking the result of the weighted average as the signal strength parameter of the detection request frame.

5. The method according to any of claims 1 to 4, wherein after said sending the probe response frame to the terminal, further comprising:

when the sending of the detection response frame fails, determining the maximum retransmission times of the detection response frame according to the signal strength parameter of the detection request frame, wherein the maximum retransmission times and the signal strength parameter have positive correlation;

and retransmitting the detection response frame according to the maximum retransmission times.

6. The method of claim 5, wherein the retransmitting the probe response frame according to the maximum number of retransmissions comprises:

randomly determining a waiting time length for retransmitting the probe response frame from a waiting window determined according to the signal strength parameter of the probe request frame, wherein at least one of the window length of the waiting window and the starting time of the waiting window has a negative correlation with the signal strength parameter;

retransmitting the probe response frame to the terminal after the waiting time length elapses from the failure of the probe request frame transmission;

when the retransmission of the detection response frame fails, adding 1 to the retransmission times to obtain updated retransmission times;

and when the updated retransmission times are less than the maximum retransmission times, continuing to execute the step of randomly determining the waiting duration for retransmitting the probe response frame in the slave waiting window until the probe response frame is successfully retransmitted.

7. A probe response apparatus, the apparatus comprising:

a receiving unit, configured to receive a probe request frame sent by a terminal;

a generating unit, configured to generate a probe response frame according to the probe request frame received by the receiving unit;

a determining unit, configured to randomly determine a waiting duration for sending the probe response frame generated by the generating unit, where the waiting duration does not exceed an timeout duration for the terminal to wait for receiving the probe response frame;

a sending unit, configured to send the probe response frame to the terminal after the waiting duration determined by the determining unit has elapsed since the probe request frame was received.

8. The apparatus according to claim 7, wherein the determining unit is specifically configured to:

acquiring a signal intensity parameter of the detection request frame;

9. The apparatus according to claim 8, wherein the determining unit is specifically configured to:

10. The apparatus according to claim 8 or 9, wherein the determining unit is specifically configured to:

11. The apparatus according to any of claims 7 to 10, wherein after said sending the probe response frame to the terminal,

the determining unit is further configured to determine, according to the signal strength parameter of the probe request frame, a maximum retransmission number of the probe response frame when the probe response frame fails to be sent, where the maximum retransmission number is in a positive correlation with the signal strength parameter;

the sending unit is further configured to retransmit the probe response frame according to the maximum retransmission times determined by the determining unit.

12. The apparatus according to claim 11, wherein the sending unit is specifically configured to:

13. A wireless Access Point (AP), the apparatus comprising: the wireless transceiver is connected with the processor;

the processor is used for receiving a probe request frame sent by a terminal by using the wireless transceiver and generating a probe response frame according to the probe request frame;

the processor is further configured to randomly determine a waiting duration for sending the probe response frame, where the waiting duration does not exceed an timeout duration for the terminal to wait for receiving the probe response frame;

the processor is further configured to send the probe response frame to the terminal using the wireless transceiver after the waiting time elapses from the reception of the probe request frame.

14. The apparatus of claim 13, wherein the processor is configured to:

acquiring a signal intensity parameter of the detection request frame;

determining a waiting window according to the signal strength parameters, wherein the window length of the waiting window and one or more signal strength parameters in the starting time of the waiting window are in a negative correlation relationship;

15. The apparatus of claim 14, wherein the processor is configured to:

searching the waiting window corresponding to the signal strength parameter from a preset window mapping, wherein the window mapping is a mapping from a signal strength parameter set to a window set, and when the starting time is unchanged, the window lengths of a plurality of waiting windows in the window set in the window mapping and a plurality of signal strength parameters in the signal strength parameter set are in a negative correlation relationship; or, when the window length is not changed, the starting time of a plurality of waiting windows in the window set in the window map and a plurality of signal strength parameters in the signal strength parameter set are in a negative correlation relationship; or, a negative correlation between the start time and the signal strength parameter, and a negative correlation between the window lengths of the multiple waiting windows in the window set in the window map and the multiple signal strength parameters in the signal strength parameter set.

16. The apparatus of claim 14 or 15, wherein the processor is configured to:

17. The apparatus of any one of claims 13 to 16, wherein after the sending of the probe response frame to the terminal, the processor is configured to:

retransmitting the probe response frame with the wireless transceiver according to the maximum retransmission number.

18. The apparatus of claim 17, wherein the processor is configured to:

retransmitting the probe response frame to the terminal by the wireless transceiver after the waiting time period elapses from the transmission failure of the probe response frame;