JP6492019B2 - Delay estimation apparatus and delay estimation method - Google Patents

Description

  The present invention relates to a delay estimation apparatus and a delay estimation method.

  For IoT (Internet of Things) devices that are expected to appear in the future, such as real-time operation control, system design, control parameter determination, information selection, and communication environment after grasping the fluctuation delay of the transmission path Need to be estimated.

  Conventionally, as a technique for estimating the variation delay, there are a method of measuring a round trip delay, a method of measuring a variation delay by time synchronization of each IoT device, and the like.

Ota et al., "Adaptive minimum filter for high-accuracy time synchronization on IP network", IEICE Technical Report 109, 436 (CS2009 73-136), IEICE, February 2010 22nd, 109, p99-104

  However, the communication quality differs depending on the way it is used, such as when a radio section is included in the uplink and downlink of the transmission path, or when the downlink occupies a wide band because there is a video download. Even if the round trip delay is measured, it is difficult to use the measurement results for system design and control parameter determination.

  In addition, the communication of the IoT device often includes a wireless section, and the accuracy of time synchronization is low. Further, it is considered that frequent time synchronization is impractical from the viewpoint of NTP (Network Time Protocol) server load and security in an IoT device having a large number of devices.

  The present invention has been made in view of the above points, and an object of the present invention is to enable estimation of a variable delay that can be used for real-time operation control of a device.

Therefore, in order to solve the above-described problem, the delay estimation device includes a receiving unit that receives information transmitted at regular intervals, and the estimated value at the regular intervals based on information attached to each of the plurality of pieces of received information. The estimation of the fixed interval from the first estimation unit to be calculated, the reception time of the newly received first information, and the reception time of the second information received immediately before the first information by comparing the time after the lapse of values, have a, a second estimation unit calculating an estimated value of delay time for said predetermined interval for the first information, the second estimation unit, When the reception time of the first information is before the time point, the delay time of the first information is estimated as 0, and after the estimated value at the fixed interval has elapsed from the reception time of the first information And the reception time of the third information received next to the first information, It is compared.

  It is possible to estimate a variable delay that can be used for real-time operation control of a device.

It is a figure for demonstrating the estimation method of the fluctuation | variation delay in embodiment of this invention. It is a figure for demonstrating the estimation method of the transmission interval in 1st Embodiment. It is a figure which shows the hardware structural example of the delay estimation apparatus in 1st Embodiment. It is a figure which shows the function structural example of the delay estimation apparatus in 1st Embodiment. It is a figure for demonstrating an example of the process sequence of the estimation process of the fluctuation | variation delay in 1st Embodiment. It is a figure for demonstrating an example of the process sequence of function t ^ (i) in 1st Embodiment. It is a figure for demonstrating the estimation method of the transmission interval in 2nd Embodiment. It is a figure for demonstrating an example of the process sequence of function t ^ (i) in 2nd Embodiment. It is a figure for demonstrating an example of a process sequence in case the process of a delay calculation function and a collection function can be performed in parallel. It is a figure which shows the 1st mounting example of a delay estimation apparatus. It is a figure which shows the 2nd mounting example of a delay estimation apparatus. It is a figure which shows the 3rd mounting example of a delay estimation apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the concept of the present embodiment will be described. In order to measure how much fluctuation delay occurs and information arrives in connection with IoT (Internet of Things) device communication, it is necessary to estimate the time t ^ when the information should arrive when there is no fluctuation delay. . In the present embodiment, as shown in FIG. 1, t ^ is estimated based on the information transmission interval of the information transmission source (the IoT device). The variable delay means a delay whose delay time is not necessarily constant. Also, the notation of t ^ in the text is

に対応する。

Corresponding to

  FIG. 1 is a diagram for explaining a variation delay estimation method according to an embodiment of the present invention. In FIG. 1, the estimation procedure of the variable delay is shown by four procedures (1) to (4).

  (1) indicates a point in time when the first information arrives from the information sending source to the information receiving destination or the information passing point (hereinafter, the receiving destination or the passing point is referred to as “receiving destination etc.”). Here, it is shown that the transmission interval at the transmission source is I.

  In (2), for the second information, the variation delay is estimated at the receiver or the like. That is, at the receiving destination or the like, the delay time for t ^ = t0 + I × 1 estimated for the second information based on the arrival times t0 and I of the first information is the variation delay of the second information. Presumed. That is, t ^ is estimated using the fact that the transmission interval I of the transmission source is constant.

  In (3), there is a case where the third information arrives earlier than t ^ = t ^ + I × 1 estimated for the third information based on t ^ and I for the second information. It is shown. In this case, t ^ is corrected when the third information arrives. That is, it is estimated that the variation delay is zero for the third information.

  (4) shows a case where the fourth information has arrived at the recipient. In this case, the delay time for t ^ = t ^ + I × 1 estimated for the fourth information based on t ^ (modified t ^) for the third information and I is the fourth information It is estimated that the delay is variable.

  Here, the problem is how the receiving party knows the transmission interval I.

  FIG. 2 is a diagram for explaining a transmission interval estimation method according to the first embodiment. In the first embodiment, the transmission interval I is estimated at the receiver or the like based on the sequence number attached to the information.

  FIG. 2 shows an example in which n pieces of information have arrived at a recipient or the like. The recipient or the like calculates I by calculating the elapsed time from the arrival of the first information of the n pieces of information to the arrival of the nth information, and dividing the measurement time by n.

  The layer to be realized is not limited to a predetermined layer. For example, an RTP (Real-time Transport Protocol) header may be used, or a sequence number in application information in the payload may be used.

  Hereinafter, the delay estimation apparatus 10 that estimates the variable delay by the above method will be described. The delay estimation device 10 corresponds to a device such as a recipient.

  FIG. 3 is a diagram illustrating a hardware configuration example of the delay estimation apparatus according to the first embodiment. The delay estimation device 10 in FIG. 3 includes a drive device 100, an auxiliary storage device 102, a memory device 103, a CPU 104, an interface device 105, and the like that are mutually connected by a bus B.

  A program that realizes processing in the delay estimation apparatus 10 is provided by a recording medium 101 such as a CD-ROM. When the recording medium 101 storing the program is set in the drive device 100, the program is installed from the recording medium 101 to the auxiliary storage device 102 via the drive device 100. However, the program need not be installed from the recording medium 101 and may be downloaded from another computer via a network. The auxiliary storage device 102 stores the installed program and also stores necessary files and data.

  The memory device 103 reads the program from the auxiliary storage device 102 and stores it when there is an instruction to start the program. The CPU 104 executes a function related to the delay estimation device 10 according to a program stored in the memory device 103. The interface device 105 is used as an interface for connecting to a network.

  FIG. 4 is a diagram illustrating a functional configuration example of the delay estimation apparatus according to the first embodiment. In FIG. 4, the delay estimation apparatus 10 includes an information reception unit 11, a transmission interval estimation unit 12, an arrival schedule estimation unit 13, a delay estimation unit 14, and the like. Each of these units is realized by processing that one or more programs installed in the delay estimation apparatus 10 cause the CPU 104 to execute.

  The information receiving unit 11 receives information transmitted from the transmission source at regular intervals. The transmission interval estimation unit 12 calculates an estimated value of the transmission interval based on the sequence number assigned to each of the received plurality of information. The arrival schedule estimation unit 13 calculates t ^ of newly received information based on the estimated value of the transmission interval and t ^ of the previously received information. The delay estimation unit 14 compares the reception time of the newly received information with t ^ related to the newly received information, and calculates an estimated value of the variation delay of the information.

  Hereinafter, a processing procedure executed by the delay estimation apparatus 10 according to the first embodiment will be described. FIG. 5 is a diagram for explaining an example of a processing procedure of a variation delay estimation process according to the first embodiment.

Information receiving unit 11, the information k the sequence number is k is the arrival substitutes the current system time to t _k (S101).

Subsequently, the delay estimation unit 14 substitutes the calculation result of t _k −t ^ (k) for d (S102). Here, t ^ (i) is a function that returns t ^ of information having the sequence number i. The processing content of the function will be described later. That is, d stores the difference between the actual arrival time of the information k and the estimated arrival time of the information k (the time to arrive if there is no variation delay).

When the value of d is larger than 0, the delay estimation unit 14 substitutes t _k −d for t ^to and substitutes d for d _k (S103). t ^~ is finally arrived information (i.e., information k in this time) is a variable that stores the time that can be regarded as a delay variation has arrived without in the drawing,

に対応する。なお、ｔ^〜は、次に到着する情報に関して、関数ｔ＾（ｋ）内において利用される。また、ｄ_ｉは、シーケンス番号がｉである情報の変動遅延の推定値を格納する変数である。すなわち、ｄ＞０の場合、ｄの値が、変動遅延として推定される。

Corresponding to In addition, ^{t ~,} with respect to the next arrival information, and is used in the function t ^ in (k). D _i is a variable for storing an estimated value of the variation delay of the information whose sequence number is i. That is, when d> 0, the value of d is estimated as the variation delay.

Subsequently, the delay estimation unit 14 substitutes the value of k for l, and substitutes the union of the set D and d _k for the set D (S105). l is a variable for storing the sequence number of the last arrived information (that is, the information k at this time), and is used in the function t ^ (k) for the next arrived information. The set D is a set of variable delays.

On the other hand, if d is 0 or less, the delay estimator 14 substitutes _{t k} to ^{t ~,} by subtracting the d from the values of the elements of the set D, and 0 is substituted into the _{d k} (S104). That is, the process corresponding to (3) in FIG. 1 is executed. Subsequently, the delay estimation unit 14 executes Step S105.

  Following step S105, the information receiving unit 11 waits until new information arrives (S106).

  Subsequently, a processing procedure of the function t ^ (i) will be described. FIG. 6 is a diagram for explaining an example of a processing procedure of the function t ^ (i) in the first embodiment.

In step S201, the transmission interval estimation unit ^12, the calculation result of _{(t ~ -t init) / (} l-k init), it is substituted into I. Here, t _init is the arrival time of the first information. K _init is a sequence number of the first information. That is, the value obtained by subtracting the arrival time of the first information from the time to arrive when the previously arrived information has no fluctuation delay, and the value obtained by subtracting the sequence number of the first information from the sequence number of the information that arrived last time The estimated value of the transmission interval I is calculated by dividing by.

Subsequently, the arrival schedule estimation unit 13 sets the calculation result of t ^to + (i−1) I as a return value of t ^ (i) (S202).

  As described above, according to the first embodiment, the transmission interval I is estimated based on the sequence number of information, and t ^ of each information is estimated using the fact that the transmission interval I is constant. Is done. Therefore, the variation delay of each information can be estimated based on t ^. If the information arrives before t ^, t ^ is corrected. Therefore, it is possible to appropriately estimate the variation delay for the subsequent information. Here, according to the present embodiment, since the processing load for estimating the variable delay can be kept low, it is possible to estimate the variable delay that can be used for real-time operation control of the device.

  For example, when an IoT device subject to operation control transmits information at intervals of several tens of msec, an event that information is unnecessary on the information receiver side occurs when there is a variable delay equivalent to the interval. According to the present embodiment, the one-way fluctuation delay can be estimated on the order of several milliseconds to several tens of milliseconds. Therefore, it is possible to estimate the communication environment by observing the change in the delay distribution within a few seconds.

  In addition, it is important to immediately detect changes in communication quality, etc. when performing operation control, and contribute to the detection of changes in communication quality by measuring and monitoring not only end-to-end but also on the network side. However, according to the present embodiment, the fluctuation delay can be estimated even at the information passing point.

  Next, a second embodiment will be described. In the second embodiment, differences from the first embodiment will be described. Points that are not particularly mentioned in the second embodiment may be the same as those in the first embodiment.

  In the second embodiment, the method for estimating the transmission interval I is different from that in the first embodiment. FIG. 7 is a diagram for explaining a transmission interval estimation method according to the second embodiment. In the second embodiment, the transmission interval I is estimated at the receiver or the like based on the time stamp attached to the information.

7 includes information time stamp t _k is attached, example in which the information added time stamp t _{k +1} arrives to receive destination or the like is shown. In this case, receipt destination, _etc., the operation result of _{t k} +1 -t _k, is estimated as the transmission interval I.

  The layer to be realized is not limited to a predetermined layer. For example, an RTP (Real-time Transport Protocol) header may be used, or a time stamp in application information in the payload may be used.

  Hereinafter, a processing procedure executed by the delay estimation apparatus 10 according to the second embodiment will be described. In the second embodiment, the processing procedure of FIG. 6 is replaced with the processing procedure shown in FIG.

  FIG. 8 is a diagram for explaining an example of a processing procedure of the function t ^ (i) in the second embodiment.

In step S301, the transmission interval estimation unit 12 substitutes the calculation result of tS _k -tS _l into I. Here, tS _k indicates a time stamp attached to information whose sequence number is k. Also, tS _l indicates a time stamp attached to information whose sequence number is l.

Subsequently, the arrival schedule estimation unit 13 sets the calculation result of t ^to + I as a return value of t ^ (i) (S302).

  As described above, according to the second embodiment, the same effect as that of the first embodiment can be obtained.

  In the processing procedure of FIG. 5 in each of the above-described embodiments, the function of the delay estimation unit 14 is separated into a delay calculation function and a collection function, and each function is executed in parallel. Improvements may be made.

  FIG. 9 is a diagram for explaining an example of a processing procedure when the processing of the delay calculation function and the collection function can be executed in parallel. In FIG. 9, steps corresponding to FIG. 5 are given common step numbers. In FIG. 9, the processing procedure of the delay calculation function is shown on the left side, and the processing procedure of the collection function is shown on the right side.

In the delay calculation function, values are not substituted into d _k and D in steps S103a to S105a. In step S105a, variable delay information including a set of sequence numbers k and d is sent to the collection function.

In the collection function, values are substituted into d _k and D in steps S103b to S105b based on k and d included in the variable delay information.

  Moreover, the delay estimation apparatus 10 in each of the above embodiments may be implemented with a configuration as shown in FIGS. 10 to 12, for example.

  FIG. 10 is a diagram illustrating a first implementation example of the delay estimation apparatus. FIG. 10 shows an example in which information is sent from device A to device B in one direction. In this case, the delay estimation device 10 may be mounted on the device B.

  FIG. 11 is a diagram illustrating a second implementation example of the delay estimation apparatus. FIG. 11 shows an example in which information is sent from both apparatus A and apparatus B to the other at a constant interval. In this case, the delay estimation device 10 may be mounted on both the device A and the device B. One or both devices may also collect bi-directional variable delays. For example, the device B may add information indicating the variation delay from the device A to the device B to the information transmitted from the device B to the device A. By doing so, bidirectional fluctuation delays can be collected in apparatus A.

  FIG. 12 is a diagram illustrating a third implementation example of the delay estimation apparatus. FIG. 12 shows an example in which the delay estimation device 10 is also mounted in a relay device related to bidirectional communication between the devices A and B. In this case, the fluctuation delay at the relay location can be measured.

  In the present embodiment, the transmission interval estimation unit 12 is an example of a first estimation unit. The delay estimation unit 14 is an example of a second estimation unit.

  As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to such specific embodiment, In the range of the summary of this invention described in the claim, various deformation | transformation・ Change is possible.

DESCRIPTION OF SYMBOLS 10 Delay estimation apparatus 11 Information receiving part 12 Transmission interval estimation part 13 Arrival schedule estimation part 14 Delay estimation part 100 Drive apparatus 101 Recording medium 102 Auxiliary storage apparatus 103 Memory apparatus 104 CPU
105 Interface device B bus

Claims (6)

A receiver for receiving information transmitted at regular intervals;
A first estimator that calculates an estimate of the fixed interval based on information attached to each of the plurality of pieces of received information;
The reception time of the first information received newly is compared with the time after the elapse of the estimated value of the predetermined interval from the reception time of the second information received immediately before the first information. A second estimation unit for calculating an estimated value of a delay time for the predetermined interval for the first information;
I have a,
The second estimation unit includes
When the reception time of the first information is before the time point, the delay time of the first information is estimated as 0, and after the estimated value at the fixed interval has elapsed from the reception time of the first information The point of time is compared with the reception time of the third information received next to the first information.
The delay estimation apparatus characterized by the above-mentioned. The first estimation unit estimates the estimated value of the constant interval based on a sequence number assigned to each of the received plurality of information.
The delay estimation apparatus according to claim 1 . The first estimating unit estimates the estimated value of the predetermined interval based on a time stamp attached to each of the plurality of pieces of received information.
The delay estimation apparatus according to claim 1 . A reception procedure for receiving information sent at regular intervals;
A first estimation procedure for calculating the estimated value of the constant interval based on information attached to each of the plurality of pieces of received information;
The reception time of the first information received newly is compared with the time after the elapse of the estimated value of the predetermined interval from the reception time of the second information received immediately before the first information. A second estimation procedure for calculating an estimated value of a delay time with respect to the predetermined interval for the first information;
The computer runs ,
The second estimation procedure includes:
When the reception time of the first information is before the time point, the delay time of the first information is estimated as 0, and after the estimated value at the fixed interval has elapsed from the reception time of the first information The point of time is compared with the reception time of the third information received next to the first information.
The delay estimation method characterized by the above-mentioned. The first estimation procedure estimates the estimated value of the fixed interval based on a sequence number attached to each of the plurality of pieces of received information.
The delay estimation method according to claim 4, wherein: The first estimation procedure estimates the estimated value of the fixed interval based on a time stamp attached to each of the plurality of pieces of received information.
The delay estimation method according to claim 4, wherein:

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