TW201935893A - Channel quality measurement system and channel quality measurement method - Google Patents

Abstract

A transmission-side channel quality measurement apparatus (110) is provided with a test packet transmission unit (111) that, via a communication unit (112) connected to a communication channel (101), sequentially transmits a plurality of test packets in a transmission period longer than a transmission period of voice packets used for voice communications. A reception-side channel quality measurement apparatus (120) is provided with: a transfer delay fluctuation calculation unit (122) that, via a communication unit (121) connected to the communication channel (101), sequentially receives the plurality of test packets, and calculates a transfer delay fluctuation indicating the magnitude of a fluctuation in transfer delay between two test packets successively received among the plurality of test packets; and a quality estimation value calculation unit (123) that, when the transfer delay fluctuation is equal to or greater than a predetermined threshold value, corrects the transfer delay fluctuation by use of a predetermined correction value, and calculates, by use of a calculated value obtained by subtracting the threshold value from the corrected transfer delay fluctuation, a quality estimation value indicating the quality of the communication channel (101).

Description

Circuit quality measurement system and method

The present invention relates to a line quality measurement system and a line quality measurement method.

In recent years, VoIP (Voice over IP) voice packet communication, which encapsulates a sound signal and transmits it through an IP (Internet Protocol) communication path, has become widespread. In VoIP, packet transmission delay or fluctuation in transmission delay may increase due to an increase in traffic on an IP line, and a packet loss rate may increase, thereby degrading voice call quality.

The increase in packet loss is the reason for the interruption of the call sound, the increase in the packet transmission delay is the cause of the response delay of the call subject, and the increase in the packet transmission delay fluctuation is the cause of the interruption of the call sound caused by the exhaustion or overflow of the buffer absorption buffer. All these cause the deterioration of voice call quality.

Then, in order to confirm whether a good call can be made in advance, a technique for transmitting a test packet over a communication line and measuring the quality of the communication line is disclosed (for example, Patent Document 1). According to this technology, in order to determine the status of the communication line, periodically transmitting test packets and observing the test packets passing through the communication line, it is possible to obtain packet loss, packet transmission delay, and packet transmission delay fluctuation.

Advance technical literature

Patent Literature:

Patent Document 1: Japanese Patent Application Laid-Open No. 2007-208326

Therefore, in order to detect fluctuations in packet transmission delay, it is necessary to pay attention to the test packet transmission interval. The packet transmission delay fluctuation is a phenomenon in which the packet transmission delay time temporarily increases and then returns to the original delay time. When the transmission period of the test packet is long, it is sometimes overlooked that the temporary delay increases.

Therefore, the transmission period of the test packet is set to be the same period or a shorter period as the transmission period of the audio packet in the actual audio communication, thereby detecting the fluctuation of the transmission delay that may occur in the audio communication. Here, in order to reduce the influence of delay due to packetization in voice packet communication, the voice is packetized with a relatively short packetization period (10 ms to 100 ms). Therefore, it is necessary to make the transmission period of the test packet shorter. Generally, the communication cost of a packet increases in response to the amount of packet transmission. Therefore, if a test packet is transmitted in a short period, the cost required to confirm the quality of the communication line will increase.

Therefore, the purpose of one or more aspects of the present invention is to accurately detect fluctuations in the delay of packet transmission even if the test packet transmission period is longer than the packet transmission period during audio communication.

According to a first aspect of the present invention, a line quality measurement system is a line quality measurement system including a first line quality measurement device and a second line quality measurement device connected to a communication line for voice communication. The first line quality is described above. The measurement device includes: a first communication unit connected to the aforementioned communication line; and a test packet transmission unit, which sequentially transmits a plurality of test packets to the aforementioned second line quality measurement device in accordance with a test transmission cycle through the first communication unit. The transmission period is a transmission period longer than the transmission period of the voice packet used for the aforementioned voice communication; the aforementioned second line quality measuring device includes: A second communication unit connected to the communication line; and a transmission delay variation calculation unit, which sequentially receives the plurality of test packets through the second communication unit, and calculates between two test packets indicating continuous reception among the plurality of test packets. The transmission delay variation of the magnitude of the transmission delay variation; and the quality estimation value calculation unit, when the transmission delay variation is greater than or equal to a preset threshold, the transmission delay variation is corrected with a preset correction value, The calculation value calculated by subtracting the threshold value from the transmission delay variation is used to calculate a quality estimation value indicating the quality of the communication line.

According to a second aspect of the present invention, a line quality measurement system includes: a line quality measurement device connected to a communication line for voice communication; and a return device; the line quality measurement device includes: a first communication unit, Connected to the aforementioned communication line; and a test packet transmission section, through the first communication section, sequentially transmitting a plurality of test packets to the return device in accordance with a test transmission cycle, the test transmission cycle is a sound more used for the aforementioned voice communication The packet transmission cycle has a longer transmission period; the aforementioned return device includes: a second communication section connected to the aforementioned communication line; and a return processing section, which sequentially receives the plurality of test packets through the second communication section, At the same time, the plurality of test packets are sequentially transmitted to the line quality measurement device through the second communication unit. The line quality measurement device further includes: a transmission delay variation calculation unit, and sequentially receives the plurality of tests through the first communication unit. Packet, which calculates the transmission delay between two test packets that are consecutively received among the plurality of test packets The transmission delay variation of the magnitude of the later variation; the quality estimation value calculation unit, when the transmission delay variation is greater than or equal to a preset threshold, corrects the transmission delay variation with a preset correction value, and based on the correction of the transmission delay variation from the correction The calculated value calculated by subtracting the threshold value is used to calculate a quality estimation value indicating the quality of the communication line.

According to a first aspect of the present invention, a line quality measurement method is a line quality measurement method for measuring the quality of a communication line for voice communication, and is characterized in that a plurality of test packets are measured in accordance with the measurement. The test transmission period is sequentially transmitted to the aforementioned communication line, and the test transmission period is a transmission period longer than the transmission period of the voice packet used for the aforementioned voice communication; the plural test packets are sequentially received from the aforementioned communication line, and the calculation is expressed. The transmission delay variation of the transmission delay variation between consecutively received two test packets among the plurality of test packets; and when the variation of the transmission delay is greater than or equal to a preset threshold, the transmission is corrected with a preset correction value. The delay variation is based on a calculated value obtained by subtracting the threshold from the corrected transmission delay variation, to calculate a quality estimated value indicating the quality of the communication line.

According to a second aspect of the present invention, a line quality measurement method is a line quality measurement method for measuring the quality of a communication line used for voice communication, and is characterized in that a plurality of test packets are sequentially transmitted to the aforementioned communication in accordance with a test transmission cycle. Line, the test transmission period is a transmission period longer than the transmission period of the voice packet used for the aforementioned voice communication; sequentially receiving the plural test packets from the aforementioned communication line; and sequentially transmitting the plural test packets back to the aforementioned communication Line; sequentially receiving the returned plural test packets from the aforementioned communication line, and calculating a transmission delay variation representing a variation in the transmission delay between two consecutively received test packets among the plural returned test packets; And when the transmission delay variation is greater than or equal to a preset threshold, the transmission delay variation is corrected with a preset correction value, and the communication line is calculated and displayed based on a calculated value obtained by subtracting the threshold from the corrected transmission delay variation. The estimated quality of the quality.

According to one or more aspects of the present invention, even if the test packet transmission period is made longer than the packet transmission period during audio communication, the fluctuation of the packet transmission delay can be accurately detected.

100, 100 #, 200, 300‧‧‧ line quality measurement system

101‧‧‧communication line

110, 110 #, 210, 310‧‧‧‧Transfer-side line quality measuring device

111, 111 #, 211, 311‧‧‧test packet transmission department

112, 212‧‧‧ Ministry of Communications

213‧‧‧Transfer Delay Variation Calculation Unit

214‧‧‧Quality estimation value calculation section

120, 120 #, 320‧‧‧ Receiver line quality measuring device

121‧‧‧ Ministry of Communications

122, 122 #, 322‧‧‧ Transmission delay variation calculation unit

123, 123 # ‧‧‧Quality estimation value calculation unit

230‧‧‧Return device

231‧‧‧Ministry of Communications

232‧‧‧Return Processing Department

140‧‧‧Memory

141‧‧‧Processor

142‧‧‧Interface

143‧‧‧Processing circuit

[FIG. 1] A block diagram schematically showing the configuration of a line quality measurement system according to the first or third embodiment.

[Fig. 2] (A) and (B) are block diagrams showing examples of hardware configuration.

3 is a flowchart showing operations of a transmission delay fluctuation calculation unit and a quality estimation value calculation unit.

[Fig. 4] A schematic diagram showing a transmission sequence of an audio packet when a packet transmission delay fluctuation occurs in audio communication.

[Fig. 5] A diagram showing an example of plotting transmission delay variation and transmission delay variation continuation time.

FIG. 6 is a diagram showing an expected value of an estimated quality value.

7 is a block diagram schematically showing a configuration of a line quality measurement system according to a modification of the first embodiment.

8 is a block diagram schematically showing a configuration of a line quality measurement system according to a second embodiment.

Embodiment 1

FIG. 1 is a block diagram schematically showing a configuration of a line quality measurement system 100 according to the first embodiment.

The line quality measurement system 100 includes a transmission line quality measurement device 110 as a first line quality measurement device, and a reception line quality measurement device 120 as a second line quality measurement device.

The transmission line quality measurement device 110 and the reception line quality measurement device 120 are connected to the communication line 101. The communication line 101 is a line for voice communication.

In the line quality measurement system 100, a test packet is transmitted from the transmission-side line quality measurement device 110, and a test packet is received by the reception-side line quality measurement device 120 to obtain the line quality.

The transmission-side line quality measuring device 110 includes a test packet transmission section 111 and a communication section 112 as a first communication section.

The test packet transmission unit 111 generates a plurality of test packets including a preset content. Then, the test packet transmission unit 111 transmits the generated test packets sequentially through the communication unit 112 according to a preset period. For example, when the measurement of the line quality is started, the test packet transmission unit 111 transmits the test packet through the communication unit 112 at a constant period Tt milliseconds. The test packet transmission unit 111 continues to execute the process of transmitting a test packet until N packets are transmitted as a preset number of packets. Therefore, N × Tt (milliseconds) is the test packet transmission time. Although N may be 2, it is usually 3 or more. Here, a period longer than the transmission period of the voice packet (for example, 1000 milliseconds) is used as the transmission period Tt of the test packet. Here, the transmission period Tt of the test packet is also referred to as a test transmission period.

The communication unit 112 is connected to the communication line 101 and communicates with the communication line 101. For example, the communication unit 112 receives a test packet generated by the test packet transmission unit 111 and transmits the test packet to the communication line 101.

The receiving-side line quality measuring device 120 includes a communication unit 121 as a second communication unit, a transmission delay fluctuation calculation unit 122, and a quality estimation value calculation unit 123.

The communication unit 121 is connected to the communication line 101 and communicates with the communication line 101. For example, the communication unit 121 receives a test packet from the communication line 101 and supplies the test packet to the transmission delay variation calculation unit 122.

The transmission delay variation calculation unit 122 sequentially receives a plurality of test packets through the communication unit 121, and calculates a transmission delay variation indicating a difference in transmission delay between two test packets received consecutively among the plurality of test packets. For example, the transmission delay variation calculation unit 122 calculates the transmission delay variation using the time when the test packet is received and the transmission period Tt of the test packet each time a test packet is received, and supplies the transmission delay variation to the quality estimation value calculation unit. 123.

The quality estimation value calculation unit 123 calculates an estimation for estimating the fluctuation based on the calculated transmission delay. Estimated quality of line quality. For example, the quality estimation value calculation unit 123 uses the transmission delay variation provided by the transmission delay variation calculation unit 122 to estimate the audio discontinuity time that occurs in the actual audio communication. Hereinafter, the estimated value of the sound discontinuity time is referred to as a quality estimated value. Specifically, the quality estimation value calculation unit 123 corrects the transmission delay variation with a preset correction value when the transmission delay variation is equal to or greater than a preset threshold value, and calculates it by subtracting the threshold value from the corrected transmission delay variation. The calculated value is used to calculate an estimated quality value indicating the quality of the communication line. The threshold here corresponds to the magnitude of the variation in the transmission delay of a voice packet in which voice interruption occurs during voice communication.

2 (A) and 2 (B) are block diagrams showing the hardware configuration of the transmission-side line quality measuring device 110 and the receiving-side line quality measuring device 120.

For example, as shown in FIG. 2 (A), a part or all of the test packet transmission unit 111, the transmission delay variation calculation unit 122, and the quality estimation value calculation unit 123 may be executed by the memory 140 and a program stored in the memory 140 may be executed. It is composed of a processor 141 such as a CPU (Central Processing Unit). Such programs can be provided through the Internet, or they can be provided on a recording medium. That is, such a program may also be provided in the form of a program product, for example.

In addition, the communication unit 112 and the communication unit 121 can be implemented through the network interface 142.

Moreover, it can also be implemented using a hardware configuration of an LSI (Large Scale Integration) integrated with the memory 140, the processor 141, and the network interface 142.

In addition, for example, as shown in FIG. 2 (B), a part or all of the test packet transmission unit 111, the transmission delay variation calculation unit 122, and the quality estimation value calculation unit 123 may be a single circuit, a composite circuit, a stylized processor, and a parallel programming. A processing circuit 143 such as a processor, ASIC (Application Specific Integrated Circuits), or FPGA (Field Programmable Gate Array) is configured.

FIG. 3 shows operations of the transmission delay fluctuation calculation unit 122 and the quality estimation value calculation unit 123. Worked flowchart. Hereinafter, the procedure for calculating the transmission delay variation of the test packet and the calculation of the estimated line quality will be described using FIG. 3.

First, when the measurement of the line quality is started, the quality estimation value calculation unit 123 sets the quality estimation value G to its initial value "0".

Next, the transmission delay variation calculation unit 122 checks whether the communication unit 121 has received the test packet. If a test packet has not been received (No in S11), the process proceeds to step S12, and if a test packet has been received (YES in S11), the process proceeds to step S13.

In step S12, the transmission delay fluctuation calculation unit 122 determines whether or not the test packet transmission time (N × Tt (milliseconds)) has elapsed, starting from the time when the line quality measurement is started. For example, the time when the first test packet for measuring the line quality is received in the communication unit 121 may be used as the starting point. Specifically, with respect to the test packet transmission time, the time after the line quality measurement is performed until the next measurement is set to be sufficiently long, the transmission delay variation calculation unit 122, after receiving the test packet finally, waits until the next time. In the case that a preset time has elapsed until a test packet is reached, the next test packet can be identified as the first test packet. When the receiving-side line quality measuring device 120 is activated, the transmission delay variation calculation unit 122 can easily identify the first test packet. When the test packet transmission time has elapsed (YES in step S12), the process proceeds to step S17, and when the test packet transmission time has not elapsed (NO in step S12), the process returns to step S11.

In step S13, the transmission delay variation calculation unit 122 calculates a transmission delay variation dt from the test packet received immediately before. Specifically, the transmission delay fluctuation calculation unit 122 calculates the transmission delay fluctuation dt based on the following formula (1).

dt = (receive time of the previous test packet)-(receive time of the test packet)-(test packet transmission period Tt) (1)

The calculated transmission delay variation dt is supplied to the quality estimation value calculation unit 123.

In addition, when the transmission delay variation calculation unit 122 has received the first test packet, steps S13 to S15 may be skipped, and the process may be performed in step S16.

Then, the quality estimation value calculation unit 123 checks whether the calculated transmission delay variation dt is equal to or more than a preset threshold TH. When the transmission delay variation dt is equal to or greater than the threshold TH (YES in S14), the process proceeds to step S15, and when the transmission delay variation dt does not reach the threshold TH (No in S14), the process proceeds to step S16.

In step S15, the quality estimation value calculation unit 123 updates the quality estimation value G.

For example, as shown in the following formula (2), the quality estimation value calculation unit 123 adds the value of the transmission delay variation dt and the preset compensation value OF to the quality estimation value G and then subtracts the threshold TH as a new quality estimation value G.

G ← G + dt + OF-TH (2)

It should be noted that what values are to be set for the threshold value TH and the compensation value OF will be described later.

In step S16, the quality estimation value calculation unit 123 confirms whether the number of test packets received so far from the start of the line quality measurement is the preset number "N". Here, "N" is a natural number of 2 or more. When the number of test packets is already "N" (YES in S16), the process proceeds to step S17, and when the number of test packets is not yet "N" (No in S16), the process returns to step S11.

In step S17, the quality estimation value calculation unit 123 supplies the quality estimation value G that has been updated so far to a part or a device that performs post-processing such as a higher-level control unit (not shown).

As described above, the estimated quality value G calculated in accordance with such a program is an estimated value of the sound discontinuity time in actual voice communication. The meaning of the estimated value is explained below, and the threshold value TH and the compensation value OF are set. value.

In the explanation, first consider the occurrence pattern of the transmission delay fluctuation of the packet. E.g. communication The processing time of a node (such as an IP router) in the line is temporarily lengthened due to an increase in load, etc., and then it is restored to the original processing time, which causes fluctuations in packet transmission delay.

FIG. 4 is a schematic diagram showing a transmission sequence of an audio packet when a transmission delay fluctuation of a packet occurs in audio communication.

In FIG. 4, the sound packet is transmitted from the sound packet transmission side according to the transmission period Ts, and the sound packet reception side receives the sound packet.

Among the transmitted packets, the first two packets P1 and P2 reach the voice packet receiving side with a normal transmission delay. The packets P3 to P5 from the third to the fifth took ds (milliseconds) longer than the normal transmission delay to reach the voice packet receiving side. The subsequent packets P6 to P11 reach the sound packet receiving side with a transmission delay that is longer than the transmission delay of packets P1 and P2 and shorter than the transmission delay of packets P3 to P5. The twelfth packet P12 is restored to the original transmission delay. In addition, the packets P6 to P12 reach the sound packet receiving side almost simultaneously.

This value ds is the difference between the transmission delay of the second packet P2 and the third packet P3. Hereinafter, the value ds represents the variation of the transmission delay in the audio packet. In addition, time a shown in FIG. 4 represents the time during which the state in which the transmission delay is longer by ds (milliseconds) continues. In the following description, this time a will be referred to as a transmission delay fluctuation continuation time.

In the voice communication, a wave absorption buffer memory is provided in the sound packet receiving side to absorb the fluctuation of the transmission delay of the packet. The tolerance of the packet transmission delay fluctuation caused by the wave absorbing buffer memory depends on the depth of the buffer memory. When the transmission delay fluctuation exceeds a critical value, a sound discontinuity occurs. Assuming that the critical value is L (milliseconds), in the packet transmission sequence shown in FIG. 4, when the transmission delay variation ds exceeds the critical value L, a ds-L (millisecond) sound interruption generally occurs. For example, in a case where a sound packet is accumulated in a fluctuation absorption buffer memory of 100 ms, 100 ms is the critical value L.

Here, returning to the operation of the quality estimation value calculation unit 123 shown in FIG. 3, the threshold value TH in steps S14 and S15 will be considered.

The purpose of introducing the threshold value TH is to prevent the estimated line quality value G from being updated due to slight transmission delay fluctuations that do not affect voice call quality.

Therefore, as the threshold value TH, a threshold value L or a value close to the threshold value L at which sound discontinuity occurs due to the above-mentioned wave absorption buffer memory is used. In this way, the update of the quality estimation value G shown in step S15 in FIG. 3 is performed only when it is observed that fluctuations in the transmission delay of the sound are interrupted.

Furthermore, in step S15, dt + OF-TH is added to the estimated quality value G to update G, where a portion of dt-TH in the added value corresponds to the sound discontinuity time.

However, because the transmission period Tt of the test packet is longer than the transmission period Ts of the audio packet during the voice communication, the value of the transmission delay variation dt observed in the transmission of the test packet is likely to be smaller than the transmission period of the same as the voice communication The transmission delay variation ds that occurs when Ts transmits a voice packet.

For example, a case where the period Tt is 10 times the period Ts will be described in FIG. 4. When a test packet is transmitted at the same time point as any of the audio packets P3 to P5 shown in FIG. 3, the transmission delay variation dt is ds (milliseconds). Here, it is assumed that the transmission delay of the transmission packet before the audio packet P1 is the same as that of P1 and P2.

When the test packet is transmitted at the same time point as any of the audio packets P6 to P11, the transmission delay variation dt is a value smaller than ds (milliseconds). In addition, when the test packet is transmitted at the same time point as the audio packets P2 and P12, the transmission delay variation dt is not measured and is 0 milliseconds.

Therefore, in order to correct the transmission delay variation dt smaller than the transmission delay variation ds, the compensation value OF is added. The value of the transmission delay variation dt is smaller than the value of the transmission delay variation ds by a small period Tt until the transmission delay variation ds, that is, ds-Tt ≦ dt ≦ ds. Therefore, a value greater than 0 and less than Tt is used as the compensation value OF. Is appropriate. Here, the compensation value OF is set to, for example, a median value of 0.5 Tt. The compensation value OF is also called a correction value.

Here, in the case where the pattern of the propagation delay fluctuation of the audio packet occurs as shown in FIG. 4, the expected value of the estimated quality value G obtained as described above is calculated as follows.

Specifically, the test packet is transmitted at the transmission period Tt. When the calculated transmission delay variation dt is equal to or greater than the critical value L of the occurrence of the sound discontinuity caused by the fluctuation absorption buffer memory, "dt + OF-L" is added to the estimated quality value G and the transmission delay variation dt does not reach the critical value In the case of L, the estimated quality value G is not added. The continuation time is time a, and the packet transmission delay variation of the transmission delay variation d (d is greater than or equal to L). After the time a elapses after the transmission delay variation occurs, the packets until the original transmission delay is restored reach the receiving side at the same time. This is equivalent to the packets P6 ~ P12 in Fig. 4 reaching the receiving side at the same time.

In addition, during a period from a time earlier than the time Tt at which the transmission delay fluctuation occurred to the time when the transmission delay fluctuation occurred, no transmission delay fluctuation occurred. This is equivalent to the fact that in the period from the time before Tt of the time of transmitting the packet P3 to the time of transmitting the packet P3 in FIG. 4, no variation in the transmission delay occurs.

In the case described above, the expected value of the calculated quality estimation value G is calculated.

First, an expected value of the estimated quality value G when a + d-L <Tt is calculated.

First, if a test packet is transmitted within time a after the transmission delay variation d occurs, the transmission delay difference dt and d observed by the test packet transmission are the same. Furthermore, the probability that the transmission delay difference dt observed by the test packet transmission is d is a / Tt. That is, the probability of calculating G = d-L + OF as the quality estimation value G is a / Tt.

In addition, after the transmission delay variation d occurs, if a test packet is transmitted from the time a to the elapsed time a + dL, the transmission delay difference dt observed by the test packet transmission is less than d and is more than L Value. Further, the probability that the transmission delay difference dt observed by the test packet transmission is L ≦ dt <d (less than d and greater than L) is (d-L) / Tt. That is, the probability that L-L + OF (= OF) to d-L + OF is calculated as the estimated quality value G is a / Tt, and the probability density is uniformly distributed.

Therefore, the expected value E (G) of the estimated quality value G is (d-L + OF) × a / Tt for the case where the observed transmission delay difference dt and d are the same, and the observed transmission delay difference dt is The case where L ≦ dt <d corresponds to the sum of {(OF + d-L + OF) / 2} × (dL) / Tt. Therefore, E (G) = (d-L + OF) × a / Tt + { (d-L + 2 × OF) / 2} × (dL) / Tt.

Then, an expected value of the quality estimation value G in a case where a + d-L ≧ Tt and a <Tt is calculated.

First, if a test packet is transmitted within time a after the transmission delay variation d occurs, the transmission delay difference dt observed by the test packet transmission is the same as d. Furthermore, the probability that the transmission delay difference dt observed by the test packet transmission is d is a / Tt. That is, the probability of calculating G = d-L + OF as the quality estimation value G is a / Tt.

In addition, after the transmission delay variation d occurs, if a test packet is transmitted from the elapsed time a to the elapsed time Tt, the transmission delay difference dt observed by the test packet transmission is less than d and d- (Tt -a) above value. Furthermore, as described above, the probability of transmitting a test packet within time a after the transmission delay variation d occurs is a / Tt. One test packet is always transmitted from the time after the transmission delay variation d occurs to Tt. Therefore, by testing The probability that the transmission delay difference dt observed in the packet transmission is smaller than d and equal to or greater than d- (Tt-a) is 1-a / Tt, and the probability density thereof is uniformly distributed.

Therefore, the expected value E (G) of the estimated quality value G is (d-L + OF) × a / Tt corresponding to the case where the observed transmission delay difference dt is the same as d, and the observed transmission delay difference dt is The case of d- (Tt-a) ≦ dt <d corresponds to the sum of [{d- (Tt-a) -L + OF + d-L + OF} / 2] × (1-a / Tt), so E (G) = (d-L + OF) × a / Tt + {(2 × d-2 × L + a-Tt + 2 × OF) / 2} × (1-a / Tt).

In addition, in the case of a ≧ Tt, a transmission delay fluctuation of the length d must be observed in the transmission of the test packet with the period Tt. Therefore, the expected value E (G) of G is E (G) = d-L + OF.

Figure 5 shows the use of an actual packet communication line for a 40 millisecond period of voice packet transmission. Observe the occurrence of transmission delay fluctuations, and plot the examples of transmission delay fluctuations that have occurred for more than 300 milliseconds and the duration of transmission delay fluctuations. In the graph shown in FIG. 5, the horizontal axis is the transmission delay variation, and the vertical axis is the transmission delay variation continuation time.

According to this figure, the transmission delay variation is not related to its continuation time. Most of the transmission delay variation continuity time (78% of the total) is within 300ms, and more than half (correctly 58% of the entire) is 100ms Within.

Therefore, for the cases where the transmission delay variation duration a is 100ms, 200ms, and 300ms respectively, the test packet transmission period Tt is 1000 milliseconds, and the critical value L of the sound discontinuity caused by the wave absorption buffer memory is 300 milliseconds and the compensation value Under the condition that OF is 1/2 (500 milliseconds) of the test packet transmission cycle, the expected value E (G) of the estimated quality value G is calculated, and the result is illustrated in FIG. 6.

In FIG. 6, the result plotted with a solid line is the actual sound discontinuity time under the above conditions (in other words, a condition where the threshold value L of the sound discontinuity caused by the wave absorption buffer memory is 300 milliseconds). When the transmission delay fluctuation continuation time a is 300 ms, the difference between the expected value E (G) and the actual sound discontinuity time becomes large, but the maximum value is 255 ms. If more than half of the cases where the transmission delay fluctuation continuation time a is less than 100 ms as shown in FIG. 5, the expected value E (G) is a value close to the actual sound discontinuity time, and the difference is less than 255 ms.

In this way, it can be seen that the relationship between the expected value E (G) of the estimated quality value G and the actual sound discontinuity time is shown in FIG. 6, and the estimated quality value G obtained according to the flowchart shown in FIG. The estimated value of the sound discontinuity time that occurs during the time N × Tt milliseconds.

The above shows that the estimated value of quality G obtained by adding the compensation value OF to the calculated transmission delay variation dt and subtracting the threshold value TH is the estimated value of the sound interruption time during a voice call, but the compensation value may not be performed. Is calculated by multiplying the specific correction value by the transmission delay variation dt. In this situation In this case, in step S13 in FIG. 3, the transmission delay fluctuation calculation unit 122 multiplies the correction value for multiplication by the transmission delay fluctuation dt and subtracts the threshold TH to calculate the transmission delay fluctuation dt.

In addition, the line quality measurement system 100 shown in FIG. 1 is obtained by using a transmission-side line quality measurement device 110 as a transmission-side line quality measurement device and a receiving-side line quality measurement device 120 as a receiving-side line quality measurement device. Outgoing line quality, Embodiment 1 is not limited to this example.

For example, as shown in the line quality measurement system 100 # shown in FIG. 7, the first line quality measurement device 110 # and the second line quality measurement device 120 # may be configured.

The first line quality measuring device 110 # includes, in addition to the test packet transmission unit 111 and the communication unit 112, a transmission delay variation calculation unit 122 and a quality estimation value calculation unit that are different from the reception-side line quality measurement device 120 shown in FIG. 123 has the same function as the transmission delay fluctuation calculation unit 122 # and the quality estimation value calculation unit 123 #.

In addition, the second line quality measuring device 120 # includes, in addition to the communication unit 121, the transmission delay variation calculation unit 122, and the quality estimation value calculation unit 123, a test packet with the transmission-side line quality measurement device 110 shown in FIG. The test packet transmission unit 111 # having the same function as the transmission unit 111.

With the configuration described above, the line quality measurement system 100 # can simultaneously obtain the transmission quality in both directions of the communication line 101.

In addition, the above description obtains a quality estimation value G for degrading the call quality due to the fluctuation of the estimated packet transmission delay, but it is also possible to measure the communication quality by calculating the absolute amount of packet transmission delay and the amount of packet loss as disclosed in Patent Document 1. The function of the device is combined with the function of the line quality measuring device that calculates the above-mentioned estimated quality value G to form a communication quality measuring device, which judges the communication quality based on the absolute amount of packet transmission delay, the amount of lost packets, and the above-mentioned estimated quality value G.

As described above, according to Embodiment 1, the test packet transmission unit 111 transmits a test packet, The transmission delay variation calculation unit 122 calculates the transmission delay variation of the received test packet. When the transmission delay variation calculated by the quality estimation value calculation unit 123 is greater than a preset threshold, the preset correction value is added to the calculated transmission. The value obtained by delay variation, and then the value obtained by subtracting the threshold value from this value, is used as the estimated quality value. Therefore, even if the test packet transmission cycle is longer than the packet transmission cycle in audio communication, the packet transmission can be estimated. Degradation of communication quality caused by delay fluctuations.

Embodiment 2

FIG. 8 is a block diagram schematically showing the configuration of a line quality measurement system 200 according to the second embodiment.

The line quality measurement system 200 includes a line quality measurement device 210 and a return device 230.

The line quality measuring device 210 and the returning device 230 are connected to the communication line 101.

In the line quality measurement system 200, the return device 230 returns a test packet transmitted from the line quality measurement device 210, and the line quality measurement device 210 receives the test packet and obtains the line quality.

The line quality measuring device 210 includes a test packet transmission unit 211, a communication unit 212 as a first communication unit, a transmission delay variation calculation unit 213, and a quality estimation value calculation unit 214.

The test packet transmission unit 211 executes the same processing as the test packet transmission unit 111 in the first embodiment, except for the process of generating a test packet.

The test packet transmission unit 211 of the second embodiment generates a test packet including a predetermined content. In the second embodiment, the test packet transmission unit 211 generates a test packet storing an echo command of the Internet Control Message Protocol (ICMP) used in the PING (Packet INternet Groper). PING is installed on almost all devices that can be connected to the IP line. It uses the ICMP echo command to send a character string to the IP address of the specified object, and confirms the smoothness of the network by replying to it. practice.

The communication unit 212 performs communication with the communication line 101. For example, the communication unit 212 receives the test packet generated by the test packet transmission unit 211, and transmits the test packet to the communication line. 101. The communication unit 212 receives a test packet from the communication line 101 and supplies the test packet to the transmission delay variation calculation unit 213.

The transmission delay fluctuation calculation unit 213 calculates a transmission delay fluctuation between the received test packets. The processing in the transmission delay fluctuation calculation unit 213 is the same as the processing in the transmission delay fluctuation calculation unit 122 in the receiving-side line quality measuring device 120 in the first embodiment.

The quality estimation value calculation unit 214 calculates a quality estimation value for estimating the line quality based on the calculated transmission delay variation. The processing in the quality estimation value calculation unit 214 is the same as the processing in the quality estimation value calculation unit 123 in the receiving-side line quality measurement device 120 in the first embodiment.

The return device 230 includes a communication section 231 and a return processing section 232.

The communication unit 231 receives a test packet from the communication line 101 and supplies the test packet to the return processing unit 232. In addition, the communication unit 231 receives a return test packet from the return processing unit 232 and transmits the test packet to the communication line 101.

The return processing unit 232, in response to the echo command stored in the test packet, provides the test packet to the communication unit 231 according to the ICMP, and returns the test packet to the line quality measuring device 210.

For example, as shown in FIG. 2 (A), a part or all of the test packet transmission unit 211, transmission delay variation calculation unit 213, quality estimation value calculation unit 214, and return processing unit 232 described above may be stored in the memory 140, and A processor 141 such as a CPU executing a program stored in the memory 140 is configured. Such programs can be provided through the Internet, or they can be provided on a recording medium. That is, such a program may also be provided in the form of a program product, for example.

The communication unit 212 and the communication unit 231 can be implemented through the network interface 142.

Moreover, it can also be implemented using a hardware configuration of an LSI (Large Scale Integration) integrated with the memory 140, the processor 141, and the network interface 142.

In addition, for example, as shown in FIG. 2 (B), a part or all of the test packet transmission unit 211, transmission delay variation calculation unit 213, quality estimation value calculation unit 214, and return processing unit 232 may be a single circuit, a composite circuit, or a program. A processing circuit 143 such as a processor, a parallel programmable processor, an ASIC, or an FPGA is configured.

As described above, according to the second embodiment, it is possible to obtain the communication quality when the communication line 101 is passed. In addition, the test packet generated by the test packet transmission unit 211 is an echo command of the ICMP used by PING, whereby the return device 230 can be a general IP line-connected device such as a personal computer. Thereby, as shown in FIG. 1 or FIG. 7, it is not necessary to provide a line quality measuring device at both ends of the communication line 101 as a measurement target, and the setting procedure can be simplified.

Embodiment 3

As shown in FIG. 1, the line quality measurement system 300 according to the third embodiment includes a transmission line quality measurement device 310 as a first line quality measurement device, and a reception line quality measurement device 320 as a second line quality measurement device. .

The transmission line quality measurement device 310 and the reception line quality measurement device 320 are connected to the communication line 101.

The transmission-side line quality measuring device 310 includes a test packet transmission section 311 and a communication section 112 as a first communication section.

The processing in the communication unit 112 in the third embodiment is the same as the processing in the communication unit 112 in the first embodiment.

The test packet transmission unit 311 executes the same processing as the test packet transmission unit 111 in the first embodiment except for the process of generating a test packet.

The test packet transmission unit 311 in the third embodiment generates a test packet including a predetermined content. real In the third embodiment, the test packet transmission unit 311 includes transmission time information indicating the transmission time of the test packet in the test packet.

The receiving-side line quality measuring device 320 includes a communication unit 121 as a second communication unit, a transmission delay fluctuation calculation unit 322, and a quality estimation value calculation unit 123.

The processing in the communication unit 121 and the estimated quality value calculation unit 123 in the third embodiment is the same as the processing in the communication unit 121 and the estimated quality value calculation unit 123 in the first embodiment.

The transmission delay fluctuation calculation unit 322 calculates a transmission delay fluctuation between the received test packets. For example, the transmission delay variation calculation unit 322 calculates the transmission delay variation using the time when the test packet is received and the transmission period Tt of the test packet each time a test packet is received, and supplies the transmission delay variation to the quality estimation value calculation unit 123. .

The transmission delay variation calculation unit 122 in Embodiment 1 calculates the transmission delay variation dt based on dt = (previous test packet reception time)-(this test packet reception time)-(test packet transmission cycle). However, the embodiment The transmission delay variation calculation unit 322 in 3 refers to the transmission time information contained in the test packet, and based on dt = (the previous test packet reception time)-(the current test packet reception time)-{(the previous test packet Transmission time)-(transmission time of this test packet)} Calculate transmission delay variation dt. In other words, the transmission delay fluctuation calculation unit 322 in Embodiment 3 calculates the transmission cycle of the test packet based on the difference in the transmission time included in the test packet.

According to the third embodiment, the transmission delay variation calculation unit 322 can accurately determine the transmission delay variation dt even if the transmission period of the test packet transmission by the test packet transmission unit 311 is changed, which can improve the design of the line quality measuring device in the third embodiment. Degrees of freedom.

The configuration of the line quality measurement system 300 according to the third embodiment is as shown in FIG. 1, and may be configured as shown in FIG. 7, and may also be configured as in the second embodiment.

Claims (9)

A line quality measurement system includes: a first line quality measurement device connected to a communication line for voice communication; and a second line quality measurement device; the first line quality measurement device includes: a first communication section, Connected to the aforementioned communication line; and a test packet transmission unit, through the aforementioned first communication unit, a plurality of test packets are sequentially transmitted to the aforementioned second line quality measuring device in accordance with the test transmission cycle, and the test transmission cycle is more suitable for the aforementioned sound The transmission period of the communication voice packet is even longer; the aforementioned second line quality measuring device includes: a second communication section connected to the aforementioned communication line; and a transmission delay variation calculation section, through the second communication section, according to Sequentially receiving the aforementioned plurality of test packets, and calculating a transmission delay variation indicating the magnitude of the variation in the transmission delay between two consecutively received test packets among the aforementioned plural test packets; and a quality estimation value calculation section, said transmission delay variation is preset If the threshold is greater than or equal to the threshold, a preset correction value is used to correct the fluctuation of the transmission delay. Transfer delay variation correction after said count subtraction calculation value calculated by the threshold calculating indicating the quality of the communication line quality estimation value. According to the line quality measurement system described in the first patent application scope, the plurality of test packets includes at least three test packets; the transmission delay variation calculation unit, and the plurality of the two packets included in the at least three test packets. In the combination, the plurality of transmission delay variations are calculated. When the quality estimation value calculation unit calculates the plurality of calculation values, the plurality of calculations are performed. The output values are totaled to calculate the above-mentioned estimated quality value. According to the line quality measurement system described in the scope of claims 1 or 2, the transmission delay variation calculation unit calculates the transmission delay variation by subtracting the test transmission period from a difference between the reception times of the two test packets. According to the line quality measurement system described in item 3 of the scope of patent application, the test packet transmission unit includes transmission time information indicating the transmission time in the plurality of test packets, and the transmission delay variation calculation unit includes the two test packets. The test transmission cycle is calculated by the difference between the transmission times indicated by the included transmission time information. According to the line quality measurement system described in the first or second scope of the patent application, the threshold is the magnitude of the transmission delay variation of the voice packet in which the voice is interrupted during the voice communication. As in the line quality measurement system described in the scope of claims 1 or 2, the correction value is a value greater than 0 and less than the test transmission period; the quality estimation value calculation unit adds the correction value from the transmission delay variation. To correct the aforementioned variation in transmission delay. A line quality measurement system comprising: a line quality measurement device connected to a communication line for voice communication; and a return device; the line quality measurement device includes: a first communication unit connected to the communication line; and The test packet transmission unit passes the plurality of test packets according to the test transmission cycle through the first communication unit. Sequential transmission to the aforementioned return device, the test transmission period is a transmission period longer than the transmission period of the voice packet used for the aforementioned voice communication; the aforementioned return device includes: a second communication section, which is connected to the aforementioned communication Circuit; and a return processing unit, which sequentially receives the plurality of test packets through the second communication unit, and simultaneously transmits the plurality of test packets to the line quality measurement device in sequence through the second communication unit; the line quality measurement The device further includes a transmission delay variation calculation unit, which sequentially receives the plurality of test packets through the first communication unit, and calculates transmissions indicating a variation in transmission delay between two consecutive test packets among the plurality of test packets. Delay variation; the quality estimation value calculation unit, when the transmission delay variation is greater than or equal to a preset threshold, the transmission delay variation is corrected with a preset correction value, and is calculated by subtracting the threshold from the corrected transmission delay variation. The calculated value is an estimated quality value indicating the quality of the communication line. A line quality measurement method is a line quality measurement method for determining the quality of a communication line for voice communication, and is characterized in that a plurality of test packets are sequentially transmitted to the aforementioned communication line in accordance with a test transmission cycle, and the test transmission cycle is In order to have a longer transmission period than the transmission period of the voice packet used for the foregoing voice communication, the plurality of test packets are sequentially received from the communication line, and the interval between the two test packets indicating the continuous reception among the plurality of test packets is calculated Transmission delay variation of the transmission delay variation; and when the transmission delay variation is greater than or equal to a preset threshold, the transmission delay variation is corrected with a preset correction value, and the threshold is subtracted from the corrected transmission delay variation. Calculated Value to calculate a quality estimate value indicating the quality of the communication line. A line quality measurement method is a line quality measurement method for determining the quality of a communication line for voice communication, and is characterized in that a plurality of test packets are sequentially transmitted to the aforementioned communication line in accordance with a test transmission cycle, and the test transmission cycle is In order to have a longer transmission period than the transmission period of the sound packet used for the aforementioned voice communication, the plurality of test packets are sequentially received from the communication line; the plurality of test packets are sequentially transmitted back to the communication line; Sequentially receiving the plurality of test packets that have been sent back, and calculating a transmission delay variation that indicates the variation in the transmission delay between two test packets that are received consecutively among the plurality of test packets that have been sent back; and When the threshold is set to be greater than or equal to, the transmission delay variation is corrected with a preset correction value, and a quality estimated value indicating the quality of the communication line is calculated based on a calculated value obtained by subtracting the threshold from the corrected transmission delay variation.