JP7032890B2 - Network quality estimation method and network quality estimation device - Google Patents

Description

The present disclosure relates to a network quality estimation method and a network quality estimation device for evaluating network quality.

In streaming applications that packetize video and audio and deliver them in real time over an IP network, the quality of the IP network has a significant impact on the quality of the transmitted video / audio. The "packet loss rate", which is the rate of occurrence of events in which IP packets transmitted from the transmitting device are lost in the network, and the rate of occurrence of events in which the arrival order of IP packets transmitted sequentially from the transmitting device is changed. A "packet order change rate" is an example of a well-known parameter for assessing the quality of an IP network. Packet loss on IP networks can cause interruptions in received video / audio. Packet reordering on IP networks can cause disturbances in the received video / audio. Therefore, appropriately evaluating or measuring the packet loss rate and the packet sequence replacement rate of an IP network is an indispensable technique for providing a streaming application with less deterioration in quality.

An IP network quality measuring device that sends a dummy packet to an IP network to estimate the quality of the IP network is already on the market. However, such devices are generally expensive. Further, since the dummy packet imposes a load on the IP network, the IP network quality measuring device is not suitable for quality measurement of the IP network used for commercial purposes. Therefore, it is desired to provide a technique capable of measuring the quality of an IP network without affecting other traffic.

Patent Document 1 discloses a technique for measuring the quality of an IP network without using a dummy packet by capturing (capturing) and evaluating an IP packet flowing through the IP network at a certain point on the IP network. Has been done. Further, Patent Document 2 discloses a technique in which a circulation buffer is provided in a device for receiving an IP packet, and the packet loss rate of the received IP packet is measured based on a detection latency determined by the chain length of the circulation buffer.

Japanese Unexamined Patent Publication No. 2005-210515 Japanese Patent Publication No. 2006-510255

The techniques disclosed in Patent Documents 1 and 2 can accurately measure the quality of an IP network such as a packet loss rate without affecting other traffic. However, these techniques require a special device (the IP packet capture device in Patent Document 1 and the circulation buffer in Patent Document 2) to be prepared, which poses a problem in terms of operation and cost.

Therefore, the present invention provides a network quality estimation method and a network quality estimation device that can be applied to streaming applications and can measure the quality of an IP network more inexpensively and easily without affecting other traffic. The purpose is to do.

In order to achieve the above object, the network quality estimation method and the network quality estimation device according to the present invention grasp the order or omission of the sequence number assigned to the packet, and the occurrence rate of packet loss or packet order change in the target network. Was decided to be estimated.

Specifically, the network quality estimation method according to the present invention is:
The sequence number acquisition procedure for acquiring the sequence number indicating the order of transmission from the current packet currently being received, and the procedure for acquiring the sequence number.
A sequence number prediction procedure for predicting the sequence number of the current packet based on the sequence number of the immediately preceding packet received immediately before the current packet, and
A network quality estimation procedure for estimating network quality based on a deviation amount which is a difference value between the sequence number of the current packet acquired in the sequence number acquisition procedure and the sequence number of the current packet predicted in the sequence number prediction procedure. ,
I do.

Further, the network quality estimation device according to the present invention is
A sequence number acquisition unit that acquires a sequence number indicating the order of transmission from the current packet currently being received, and a sequence number acquisition unit.
A holding unit that holds the sequence number of the packet acquired by the sequence number acquisition unit, and a holding unit.
The difference between the sequence number of the current packet acquired by the sequence number acquisition unit and the sequence number of the current packet predicted based on the sequence number of the immediately preceding packet received immediately before the current packet held by the holding unit. A deviation amount calculation unit that calculates a certain deviation amount, and a deviation amount calculation unit
A network quality calculation unit that estimates network quality based on the deviation amount calculated by the deviation amount calculation unit, and a network quality calculation unit.
To prepare for.

The network quality estimation method and the network quality estimation device are premised on the fact that a "sequence number" indicating the transmission order is assigned to the packet to be measured. Normally, the header of an RTP (Real-Time Transport Protocol) packet used in a streaming application is given a "sequence number" which is a counter value that is incremented by 1 according to the transmission order.

The network quality estimation method and the network quality estimation device sequentially extract the "sequence number s (k)" of the packet from the received packet. s (k) means that it is the sequence number of the packet received by the measuring device at the kth position. Then, in the network quality estimation method and the network quality estimation device, the sequence number s (k) of the k-th received packet and the sequence number s (k-1) of the k-1th received packet immediately before the sequence number s (k). ), The "deviation amount G (k)", which is the difference from the value (predicted sequence number of the current packet) that would have been obtained as the sequence number s (k), is calculated each time a packet is received. Then, for network quality evaluation, the packet loss rate and the packet order replacement rate, which will be described later, are simply calculated using this “deviation amount”.

By simply mounting this network quality estimation device on the receiving device or connecting it to a part of the network, it is possible to estimate the rate of occurrence of packet loss and packet reordering in the network. Therefore, the present invention provides a network quality estimation method and a network quality estimation device that can be applied to streaming applications and can measure the quality of an IP network cheaper and easier without affecting other traffic. can do.

INDUSTRIAL APPLICABILITY The present invention provides a network quality estimation method and a network quality estimation device that can be applied to a streaming application and can measure the quality of an IP network cheaper and easier without affecting other traffic. Can be done.

It is a figure explaining the packet structure. It is a figure explaining the packet loss rate and the packet order exchange rate. It is a figure explaining the receiving apparatus provided with the network quality estimation apparatus which concerns on this invention. It is a figure explaining the network quality calculation part of the network quality estimation apparatus which concerns on this invention. It is a figure explaining the network quality estimation method which concerns on this invention. It is a figure explaining a special case in the network quality estimation method which concerns on this invention. It is a figure explaining a special case in the network quality estimation method which concerns on this invention. It is a figure explaining a special case in the network quality estimation method which concerns on this invention. It is a figure explaining a special case in the network quality estimation method which concerns on this invention.

An embodiment of the present invention will be described with reference to the accompanying drawings. The embodiments described below are examples of the present invention, and the present invention is not limited to the following embodiments. In addition, the components having the same reference numerals in the present specification and the drawings shall indicate the same components.

[Packet configuration]
The configuration of the packet used in this embodiment will be described. For packets transmitted over the network (which are packets transmitted by the transmitting device and received by the receiving device), the counter value is incremented by 1 according to the order in which the transmitting device transmits the packets. "Sequence number" is given. The sequence number is a numerical value indicating the order in which packets are transmitted. The sequence number is stored in a predetermined area of the packet header (including the extension header). Alternatively, the sequence number may be stored in a predetermined area provided in the payload of the packet.

A more specific example of the packet configuration that can be used in the present invention will be described with reference to FIG. The coded data obtained by encoding video, audio, etc. is stored in the payload of an RTP (Real-Time Protocol) packet. An RTP header is added to the RTP payload to form an RTP packet. As shown in FIG. 1, the RTP header includes a version (V), a padding (P), an extended header (X), a CSRC count (CC), a marker (M), a payload type, a sequence number, a time stamp, and synchronization. Each region of the source (SSRC) identifier is provided. The sequence number area of the RTP header composed of 16 bits stores a sequence number starting from 1 and incrementing by 1 according to the transmission order of RTP packets. The RTP packet is stored in a UDP (User Datagram Protocol) payload. A UDP header is added to the UDP payload to form a UDP packet. UDP packets are stored in an IP (Internet Protocol) payload. An IP header is added to the IP payload to form an IP packet. The IP packet is transmitted from the transmitting device to the receiving device via the IP network.

The packet that can be used in the present invention is not limited to the above-mentioned RTP packet. The present invention can be applied to a packet of any format as long as a sequence number indicating the transmission order of the packet is added to the header or payload of the packet.

[Outline of processing]
The outline of the network quality estimation process will be described with reference to FIG. FIG. 2A is a diagram illustrating an outline of an estimation method of the “packet loss rate”, and FIG. 2B is a diagram illustrating an outline of an estimation method of the “packet order replacement rate”.

It is assumed that the IP packet transmitting device transmits 10 IP packets each having sequence numbers 1, 2, 3, ... 10 which are incremented by 1 from 1 to 10. These 10 IP packets are received by the receiving device via the IP network. As shown in FIGS. 2 (a) and 2 (b), there are nine receiving devices in the order of sequence number s (k) = 1, 3, 4, 5, 6, 8, 9, 7, and 10. Suppose you have received an IP packet.

ここで、差分値Ｇ（ｋ）を「ずれ量」と呼ぶこととする。 Here, the sequence number of the IP packet received by the receiving device at the kth position from the start of measurement is referred to as s (k). Each time the receiver receives the kth (ie, latest) IP packet, it takes the value (s (k-1) + 1) that would have been obtained as the sequence number s (k) of the latest IP packet. Predict. Then, the receiving device calculates the difference value G (k) between the latest sequence number s (k) and the predicted sequence number s (k-1) + 1.

Here, the difference value G (k) is referred to as a "deviation amount".

If the kth received IP packet is transmitted one after the k-1st received IP packet, the sequence number s (k) is set to a value one larger than the sequence number s (k-1). Since it should be, the deviation amount G (k) becomes 0. On the other hand, when packet loss or replacement of the packet arrival order occurs, the sequence number s (k) does not become a value 1 larger than the sequence number s (k-1). For example, when one packet loss occurs, the sequence number s (k) should be a value 2 larger than the sequence number s (k-1), so the deviation amount G (k) is 1. In the examples of FIGS. 2 (a) and 2 (b), the sequence number of the second (k = 2) received IP packet is s (k) = 3, and the sequence number immediately before (k = 1) is Since the sequence number of the received IP packet is s (k) = 1, the deviation amount calculated at this time is G (k) = 3- (1 + 1) = + 1. The receiving device calculates the deviation amount G (k) each time it receives an IP packet, and estimates the packet loss rate and the packet order replacement rate using this “deviation amount G (k)”.

(Packet loss rate)
An outline of the packet loss rate estimation process will be described with reference to FIG. 2A. When the receiving device receives the last IP packet in the predetermined period (k = 9 in FIG. 2A), the receiving device adds all the deviation amounts G (k) obtained so far and accumulates the deviation amount ΣG ( k) (1) in the example of FIG. 2 (a) is calculated. The receiving device derives the ratio of the maximum sequence number S _max (10 in the example of FIG. 2A) and the cumulative deviation amount ΣG (k) in the IP packet received in the predetermined period as the packet loss rate P _Loss .

累積ずれ量フラグΣＮＧ（ｋ）は、パケット到着順序の入れ替えが発生したパケット数を表している。なお、「これまでに得られたすべてのずれ量フラグＮＧ（ｋ）を加算」することは、「負数のずれ量Ｇ（ｋ）をカウントする」ことと等価である。 (Packet order replacement rate)
Next, an outline of the packet order replacement rate estimation process will be described with reference to FIG. 2 (b). Each time the receiving device receives an IP packet, the receiving device evaluates whether or not the calculated deviation amount G (k) is a negative value. When the calculated deviation amount G (k) is a negative value, the deviation amount flag NG (k) = 1 in the kth received IP packet is set. In other cases, the deviation amount flag NG (k) = 0 (see formula C3). When the receiving device receives the last IP packet in the predetermined period (k = 9 in FIG. 2B), the receiving device adds all the deviation amount flags NG (k) obtained so far and the cumulative deviation amount flag. ΣNG (k) (1) in the example of FIG. 2B is calculated. The receiving device derives the ratio of the maximum sequence number S _max (10 in the example of FIG. 2B) and the cumulative deviation amount flag _ΣNG (k) in the IP packet received in the predetermined period as the packet order replacement rate P Reader. do.

The cumulative deviation amount flag ΣNG (k) represents the number of packets in which the packet arrival order has been changed. It should be noted that "adding all the deviation amount flags NG (k) obtained so far" is equivalent to "counting the deviation amount G (k) of a negative number".

In the above, the maximum sequence number S _max in the received IP packet is used as the denominator for calculating the packet loss rate and the packet sequence replacement rate, but the present invention is not limited thereto. In short, the number of transmitted packets corresponding to the received packets targeted for measurement (in the examples of FIGS. 2A and 2B, the number of received packets is 9, but one packet loss occurs in the network. Therefore, the number of transmitted packets may be estimated to be 10) and used as the denominator for calculating the packet loss rate and the packet order replacement rate. For example, S _max − S _min -1 may be used as the denominator by using the maximum sequence number S _max and the minimum sequence number S _min among the received IP packets (Formula C2 and Formula C4). In this case, the packet loss rate and the packet order replacement rate can be calculated even when the sequence number of the first transmitted IP packet among the measurement targets is other than 1.

でパケット損失率Ｐ_Ｌｏｓｓを、

でパケット順序入替率Ｐ_{Ｒｅｏｒｄｅｒ}を導出する。また、あらかじめ測定対象のパケット数が決まっている場合は、送信装置がパケットのヘッダ等に送信パケット数に関する情報を格納することで、送信装置が受信装置に伝達するようにしてもよい。 That is, when the minimum value S _min of the sequence number of the IP packet for a predetermined period is not 1,

Packet loss rate P _Loss ,

To derive the packet order replacement rate P _Reader . Further, when the number of packets to be measured is determined in advance, the transmitting device may store information on the number of transmitted packets in the header or the like of the packet so that the transmitting device transmits the information to the receiving device.

[Network quality estimator]
FIG. 3 is a diagram illustrating a configuration of a receiving device 301 including a network quality estimation device 101 according to the present embodiment. The receiving device 301 includes a receiving buffer 11 for receiving a packet from the network, a packet processing unit 12 for receiving and processing the packet, and a network quality estimation device 101. The network quality estimation device 101 is incorporated in the receiving device 301 for receiving the IP packet, or is configured integrally with the receiving device 301. In the network quality estimation device 101, the sequence number is notified from the packet processing unit 12, and as the network quality, the "packet loss rate" is the rate at which the IP packet transmitted from the transmission device is lost in the network. , The "packet order change rate", which is the rate of occurrence of an event in which the arrival order of IP packets sequentially transmitted from the transmitting device is changed, is estimated according to the principle described with reference to FIG.

The network quality estimation device 101 is
The sequence number acquisition unit 13 for acquiring the sequence number indicating the order of transmission from the current packet currently being received, and the sequence number acquisition unit 13.
The holding unit 14 that holds the sequence number of the packet acquired by the sequence number acquisition unit 13 and
Difference value between the sequence number of the current packet acquired by the sequence number acquisition unit 13 and the sequence number of the current packet predicted based on the sequence number of the immediately preceding packet received immediately before the current packet held by the holding unit 14. The deviation amount calculation unit 15 for calculating the deviation amount, and
A network quality calculation unit 16 that estimates network quality based on the deviation amount calculated by the deviation amount calculation unit 15.
To prepare for.

The sequence number acquisition unit 13 acquires the sequence number s (k) included in the IP packet to be notified each time the packet processing unit 12 receives the IP packet. The sequence number acquisition unit 13 outputs the sequence number s (k) of the latest (kth) IP packet to the holding unit 14 and causes the holding unit 14 to hold the sequence number s (k).

The holding unit 14 is the most of the latest IP packet sequence number s (k), the sequence number s (k-1) of the IP packet received immediately before the latest IP packet, and the sequence number held by the holding unit 14 over a predetermined period. It holds the small sequence number S _min and the largest sequence number S _max .

The deviation amount calculation unit 15 is based on the value of the sequence number s (k-1) of the IP packet received immediately before (k-1st) held by the holding unit 14, and the sequence number s of the latest IP packet. Predict the value (s (k-1) +1) that would have been obtained as (k). Then, the deviation amount calculation unit 15 has a deviation amount G (k) which is a difference value between the latest sequence number s (k) acquired by the sequence number acquisition unit 13 and the predicted sequence number s (k-1) + 1. Is calculated and output to the network quality calculation unit 16.

FIG. 4 is a diagram illustrating a specific configuration of the network quality calculation unit 16. The network quality calculation unit 16 includes a packet loss rate calculation unit 20 for calculating the packet loss rate and a packet order replacement rate calculation unit 30 for calculating the packet order replacement rate. The packet loss rate calculation unit 20 includes an addition unit 21, a cumulative deviation amount holding unit 22, and a division unit 23. The packet order replacement rate calculation unit 30 includes a determination unit 31, an addition unit 32, a cumulative deviation amount flag holding unit 33, and a division unit 34.

The packet loss rate calculation unit 20 estimates the packet loss rate according to the above-mentioned number C2. In the addition unit 21, the latest (kth) deviation amount G (k) output by the deviation amount calculation unit 15 and the previous (k-1th) accumulation held by the cumulative deviation amount holding unit 22 are accumulated. The latest cumulative deviation amount ΣG (k) is calculated by adding the deviation amount ΣG (k-1). The addition unit 21 outputs and holds the cumulative deviation amount ΣG (k) to the cumulative deviation amount holding unit 22 and outputs it to the division unit 23. The division unit 23 acquires the maximum sequence number S _max and the minimum sequence number S _min held by the holding unit 14, and calculates the number C2. That is, the cumulative deviation amount ΣG (k) is divided by (S _max − S _min − 1). The division unit 23 outputs the value obtained by division as an estimated value of the packet loss rate P _Loss .

The packet order replacement rate calculation unit 30 estimates the packet order replacement rate according to the above-mentioned number C4. The determination unit 31 evaluates whether or not the latest (kth) deviation amount G (k) output by the deviation amount calculation unit 15 is a negative value. The determination unit 31 sets the deviation amount flag NG (k) = 1 when the deviation amount G (k) is a negative value according to the number C3, and the deviation amount flag NG (k) = 0 in other cases. And set. The addition unit 32 has the latest (kth) deviation amount flag NG (k) value output by the determination unit 31 and the previous (k-1th) value held by the cumulative deviation amount flag holding unit 33. The latest cumulative deviation amount flag ΣNG (k) is calculated by adding the cumulative deviation amount flag ΣNG (k-1). The addition unit 32 outputs and holds the cumulative deviation amount flag ΣNG (k) to the cumulative deviation amount flag holding unit 33, and outputs the cumulative deviation amount flag ΣNG (k) to the division unit 34. The division unit 34 acquires the maximum sequence number S _max and the minimum sequence number S _min held by the holding unit 14, and calculates the number C4. That is, the cumulative deviation amount flag ΣNG (k) is divided by (S _max − S _min − 1). The division unit 34 outputs the value obtained by division as an estimated value of the packet order replacement rate _Reader .

By inputting a reset signal to the holding unit 14, the cumulative deviation amount holding unit 22, and the cumulative deviation amount flag holding unit 33 after the lapse of a predetermined period or at an arbitrary time, the values held by them are reset (initialized). be able to. For example, the predetermined period may be a certain period required for estimating the network quality. Alternatively, it may be the time to receive from the packet with the minimum value of the sequence number to the packet with the maximum value of the sequence number.

FIG. 5 is a flowchart illustrating a network quality estimation method performed by the network quality estimation device 101 according to the present embodiment. This network quality estimation method is
A sequence number acquisition procedure (step S01) for acquiring a sequence number indicating the order of transmission from the current packet currently being received, and
A sequence number prediction procedure for predicting the sequence number of the current packet based on the sequence number of the immediately preceding packet received immediately before the current packet, and
A network quality estimation procedure for estimating network quality based on the amount of deviation (step S02) between the sequence number of the current packet acquired in the sequence number acquisition procedure and the sequence number of the current packet predicted in the sequence number prediction procedure (step S02). Step S03) and
I do.
Here, the deviation amount in step S02 may be a value calculated by using the above-mentioned number 1.

In the network quality estimation procedure (step S03), it is determined in step S31 whether or not the deviation amount G (k) is a negative value, and if the deviation amount G (k) is a negative value, the deviation amount flag NG (k). = 1 is set (step S33), and in other cases, the deviation amount flag NG (k) = 0 is set (step S32). Then, the difference between the minimum sequence number S _min and the maximum sequence number S _max among the packets received in the predetermined period is calculated (step S34). Then, the packet loss rate P _LOSS is calculated according to the number C2 (step S35), and the packet order replacement rate P _Reader is calculated according to the number C4 (step S36).

[Special case]
Here, it is noted that the sequence number stored in the received packet is a finite value. For example, in the case of an RTP packet, the area for storing the sequence number is only 16 bits as shown in FIG. That is, the RTP packet can only store a decimal value from 0 to 65535 as the sequence number. When the sequence number reaches 65535, it returns to 0 and is incremented again. Hereinafter, it is assumed that a 16-bit sequence number storage area is allocated to the packet, and the deviation amount G (k) at the timing when the sequence number of the received packet returns from 65535 to 0 will be considered.

When a packet having the sequence number s (k) = 0 is received, the sequence number of the received packet immediately before the packet is s (k-1) = 65535, so that the packet is deviated as shown in FIG. 6A. The amount G (k) = −65536. Therefore, even if there is no packet loss during the network quality evaluation period, the cumulative deviation amount (that is, the estimated value of the packet loss amount) is calculated as ΣG (k) = −65536, which is an unreasonable value.

(Countermeasure 1)
Therefore, as shown in FIG. 6B, when the maximum value of the sequence number (65535 in decimal in the example of the 16-bit value) is reached, or when the sequence number returns to the initial value (usually 0). Then, the cumulative deviation amount ΣG (k) and the cumulative deviation amount flag ΣNG (k) may be reset (initialized). That is, when the sequence number s (k) acquired from the packet processing unit 12 is 65535 (or 0), the sequence number acquisition unit 13 outputs a reset signal and holds it in the holding unit 14. The value, the value held in the cumulative deviation amount holding unit 22 and the cumulative deviation amount flag holding unit 33 in the network quality calculation unit 16 are reset or erased, and the deviation amount again from the sequence number s (k-1) = 1. G (k) may be calculated.

That is, the sequence number acquisition unit 13 resets the holding unit 14 and the network quality calculation unit 16 when the maximum sequence number that can be assigned to the packet is acquired or the initial value of the sequence number assigned to the packet is acquired. Perform a reset operation. Specifically, the sequence number acquisition unit 13 resets the s (k), s (k-1), S _max , and S _min held by the holding unit 14 by the reset operation, and the network quality calculation unit 16 Resets the cumulative deviation amount Σ _{k = 2} [G (k)] and the cumulative deviation amount flag Σ _{k = 2} [NG (k)] calculated by.

(Countermeasure 2)
Even if the estimation of the packet loss rate or the packet order replacement rate is reset when the sequence number receives the maximum value, it is a problem if the received packets are replaced before and after the timing when the sequence number returns from the maximum value to the initial value. May occur. For example, when the packet having the maximum sequence number (s (k) = 65535) and the packet having the sequence number one smaller than the maximum value (s (k) = 65534) are received in an alternating order, FIG. 7A ), The deviation amount G (k) = -65535 is calculated at the timing when s (k) = 0 is received even after the sequence number s (k) = 65535 is received and reset. Will be done. As a result, even if no packet loss occurs thereafter, an unreasonable value of ΣG (k) = −65535 is calculated as the cumulative deviation amount. Further, when the packet having the initial value of the sequence number (s (k) = 0) and the packet having the sequence number one larger than the initial value (s (k) = 1) are received in an alternating order, FIG. 7 (b) ), The cumulative deviation amount ΣG (k) = -1 is calculated even after the sequence number s (k) = 65535 is received and reset, and the estimated value of the packet loss amount is calculated. An invalid value of -1 will be calculated.

ただし、Ｍａｘ Ｓはパケットに付与可能な最大のシーケンス番号である。 Therefore, when a packet having the maximum sequence number is received, the deviation amount G (k) with respect to the next received packet may be a value that matches the sequence number of the received packet. In other words, when the sequence number of the previous received packet is the maximum value (s (k) = 65535), the deviation amount may be a value that matches the sequence number of the received packet. This can be expressed as an expression as follows.

However, Max S is the maximum sequence number that can be assigned to the packet.

If the number C5 is used, the network quality will be reached when the maximum value of the sequence number (65535 in decimal in the 16-bit value example) is reached, or when the sequence number returns to the initial value (usually 0). There is no need to reset the estimation. Even if the same received packet replacement as in FIG. 7A occurs, if the number C5 is used, a reasonable value can be obtained for the cumulative deviation amount as shown in FIG. 8A. Similarly, even if the same received packet replacement as in FIG. 7 (b) occurs, a reasonable value can be obtained for the cumulative deviation amount as shown in FIG. 8 (b).

(Countermeasure 3)
Even when the formula C5 is used to calculate the deviation amount, if the packet with sequence number s (k) = 65535, which is the key to solving the problem, is lost in the network and is not received, the deviation amount and the deviation amount are not received. An invalid value will be calculated as a flag. As shown in FIG. 9A, when the packet with the sequence number s (k) = 65535 is not received, when the packet with the sequence number s (k) = 0 is received, the deviation amount G (k) = −. 65535 and the deviation amount flag NG (k) = 1 are calculated.

Therefore, if the packet with the maximum sequence number is lost, the deviation amount G (k) calculated from the received packets before and after this packet should not be used for calculating the packet loss rate or the packet order replacement rate. Just do it. Specifically, the network quality calculation unit 16 sets a negative threshold value Gth for the deviation amount G (k), and the deviation amount calculation unit 15 sets a negative deviation amount G (k) less than Gth. If the positive deviation amount for compensating for the negative deviation amount G (k) is not calculated within a certain period shorter than the predetermined period before and after the calculation is performed and the negative deviation amount G (k) is calculated, the negative deviation amount is negative. The deviation amount G (k) is replaced with G (k) = 1.

That is, when a deviation amount G (k) smaller than a predetermined negative threshold value Gth is calculated, a positive deviation amount for compensating for this deviation amount must be calculated within a certain period before and after the calculation of this deviation amount. , The amount of deviation may be changed to G (k) = 1 by assuming that the packet having the maximum sequence number has been lost.

For example, an example will be described in which a predetermined negative threshold value Gth = -60000 and a fixed period is set to a period corresponding to the number of received packets 6. It is assumed that a packet (s (k) = 65534) having a sequence number smaller than the maximum value is received and then a packet (s (k) = 0) having an initial value of the sequence number is received. At this time, the deviation amount is calculated as G (k) = −65535 (<Gth), and the deviation amount flag is calculated as NG (k) = 1. If the amount of deviation of G (k) = -Gth (this value becomes positive) is not calculated over 3 packets (6 packets in total) before and after that, the packet with the maximum sequence number (s (k) = 65535). Is considered to be lost, and as shown in FIG. 9 (b), the deviation amount calculated when the packet (s (k) = 0) having the initial value of the sequence number is received is set to G (k) = 1. Change and change to NG (k) = 0 based on it. This process means that the deviation amount is set to G (k) = 1 in response to the loss of the packet having the maximum sequence number. As a result, the cumulative deviation amount becomes ΣG (k) = 1 (that is, the packet loss amount 1), and the number of packet replacements is corrected to 0. In this example, a certain period is set as a period corresponding to the number of received packets 6, but it may be changed as appropriate depending on the network configuration and conditions.

Here, the minimum value that can be used as the predetermined negative threshold value Gth is a value that is one larger than the value with the maximum value of the sequence number as a negative number. For example, when the sequence number is represented by 16 bits as shown in FIG. 1 (the maximum value of the sequence number is 65535), the minimum value that can be used as a predetermined negative threshold Gth is −65534. The deviation amount G (k) is less than −65534 when only the packet having the maximum sequence number (s (k) = 65535) is lost, as shown in FIG. 9A. .. On the other hand, if a predetermined negative threshold value Gth = −65534 is used, it is not possible to compensate for the loss of a plurality of consecutive packets including the packet having the maximum sequence number. For example, consider the case where three packets having sequence numbers s (k) of 65533 to 65535 are continuously lost. Following the reception of the packet with sequence number s (k) = 65532, when the packet with sequence number s (k) = 0 is received, the deviation amount is calculated as G (k) = 0- (65532 + 1) = -65533. To. When Gth = -65534 is used as the predetermined negative threshold value, this deviation amount is not corrected, and therefore the cumulative deviation amount is also calculated as ΣG (k) = -65555, which is an invalid value. Therefore, as the predetermined negative threshold Gth, in consideration of the number of packets that may be continuously lost, a value having a negative number larger than "a value one larger than the value obtained by setting the maximum value of the sequence number as a negative number" is set. You may use it. As in the above example, when there is a possibility that a maximum of 3 packets are continuously lost, the predetermined negative threshold value may be Gth = −65532.

(The invention's effect)
In the network quality estimation method and the network quality estimation device according to the present invention, the value of the sequence number s (k) of the packet received at the kth position and the sequence number s (k-1) of the packet received immediately before the sequence number s (k). Therefore, the packet loss rate and the packet order replacement rate are calculated based on the "deviation amount G (k)" which is the difference from the value that would have been obtained as the sequence number s (k). Since it is not necessary to send a dummy packet for network quality measurement and the network quality can be calculated only by addition / subtraction, the present invention makes it cheaper and easier to measure the network quality without affecting other traffic. You will be able to.

Patent Documents 1 and 2 are devices invented for accurately measuring network quality. On the other hand, the present invention is a device invented for measuring network quality inexpensively and easily without requiring high accuracy as in Patent Documents 1 and 2, and is the object of the inventions of Patent Documents 1 and 2. I should add that is different.

11: Receive buffer 12: Packet processing unit 13: Sequence number acquisition unit 14: Holding unit 15: Deviation amount calculation unit 16: Network quality calculation unit 20: Packet loss rate calculation unit 21: Cumulative deviation amount holding unit 22: Dividing unit 30 : Packet order replacement rate calculation unit 31: Judgment unit 32: Cumulative deviation amount flag holding unit 33: Dividing unit 101: Network quality estimation device 301: Receiver device

Claims (10)

The sequence number acquisition procedure for acquiring the sequence number indicating the order of transmission from the current packet currently being received, and the procedure for acquiring the sequence number.
A sequence number prediction procedure for predicting the sequence number of the current packet based on the sequence number of the immediately preceding packet received immediately before the current packet, and
A network quality estimation procedure that estimates the packet loss rate based on the amount of deviation, which is the difference between the sequence number of the current packet acquired in the sequence number acquisition procedure and the sequence number of the current packet predicted in the sequence number prediction procedure. When,
Is a network quality estimation method that performs
In the network quality estimation procedure, the packet loss rate is a value obtained by dividing the cumulative deviation amount obtained by adding all of the deviation amounts over a predetermined period by the number of packets to be received over the predetermined period calculated from the sequence number. A network quality estimation method characterized by that. When the maximum sequence number that can be assigned to a packet is acquired or the minimum sequence number that can be assigned to a packet is acquired in the sequence number acquisition procedure, the sequence number acquisition procedure, the sequence number prediction procedure, and the sequence number prediction procedure are performed again. The network quality estimation method according to claim 1, wherein a reset procedure for starting the network quality estimation procedure is performed. When the sequence number of the immediately preceding packet is the maximum sequence number that can be assigned to the packet, the network quality estimation procedure starts the sequence number acquisition procedure, the sequence number prediction procedure, and the network quality estimation procedure again. The network quality estimation method according to claim 1, wherein the sequence number of the current packet is used as the deviation amount without performing a reset procedure. In the network quality estimation procedure, the deviation amount is a negative deviation amount smaller than a predetermined negative threshold value, and the negative deviation amount is within a certain period shorter than the predetermined period before and after the calculation of the negative deviation amount. The network quality estimation method according to claim 3, wherein when the positive deviation amount for compensating the amount is not calculated, the negative deviation amount is replaced with 1. The sequence number acquisition procedure for acquiring the sequence number indicating the order of transmission from the current packet currently being received, and the procedure for acquiring the sequence number.
A sequence number prediction procedure for predicting the sequence number of the current packet based on the sequence number of the immediately preceding packet received immediately before the current packet, and
Network quality estimation that estimates the packet order replacement rate based on the amount of deviation, which is the difference between the sequence number of the current packet acquired in the sequence number acquisition procedure and the sequence number of the current packet predicted in the sequence number prediction procedure. Procedure and
Is a network quality estimation method that performs
In the network quality estimation procedure, a deviation amount flag that sets “1” when the deviation amount is a negative value and “0” in other cases is used, and the deviation amount flag is added over a predetermined period to accumulate the deviation amount. The value obtained by dividing the quantity flag by the number of packets to be received over the predetermined period calculated from the sequence number is used as the packet order replacement rate.
If the sequence number of the immediately preceding packet is the maximum sequence number that can be assigned to the packet, the reset procedure for starting the sequence number acquisition procedure, the sequence number prediction procedure, and the network quality estimation procedure is not performed again. The sequence number of the current packet is set as the deviation amount, and the deviation amount is a negative deviation amount smaller than a predetermined negative threshold value, and the deviation amount is from the predetermined period before and after the calculation. A network quality estimation method comprising replacing the negative deviation amount with 1 when the positive deviation amount for compensating for the negative deviation amount is not calculated within a short fixed period. A sequence number acquisition unit that acquires a sequence number indicating the order of transmission from the current packet currently being received, and a sequence number acquisition unit.
A holding unit that holds the sequence number of the packet acquired by the sequence number acquisition unit, and a holding unit.
The difference between the sequence number of the current packet acquired by the sequence number acquisition unit and the sequence number of the current packet predicted based on the sequence number of the immediately preceding packet received immediately before the current packet held by the holding unit. A deviation amount calculation unit that calculates a certain deviation amount, and a deviation amount calculation unit
A network quality calculation unit that estimates the packet loss rate based on the deviation amount calculated by the deviation amount calculation unit.
It is a network quality estimation device equipped with
The network quality calculation unit uses the packet loss rate as a value obtained by dividing the cumulative deviation amount obtained by adding all of the deviation amounts over a predetermined period by the number of packets to be received over the predetermined period calculated from the sequence number. A network quality estimator characterized by that. The sequence number acquisition unit resets the holding unit and the network quality calculation unit when the maximum sequence number that can be assigned to the packet is acquired or the minimum sequence number that can be assigned to the packet is acquired. 6. The network quality estimation device according to claim 6. When the sequence number of the immediately preceding packet is the maximum sequence number that can be assigned to the packet, the deviation amount calculation unit does not perform a reset operation to reset the holding unit and the network quality calculation unit, and the current packet. The network quality estimation device according to claim 6 , wherein the sequence number of the above is used as the deviation amount. The network quality calculation unit has a negative deviation amount whose deviation amount is smaller than a predetermined negative threshold value, and the negative deviation amount is within a certain period shorter than the predetermined period before and after the calculation of the negative deviation amount. The network quality estimation device according to claim 8, wherein when the positive deviation amount for compensating the amount is not calculated, the negative deviation amount is replaced with 1. A sequence number acquisition unit that acquires a sequence number indicating the order of transmission from the current packet currently being received, and a sequence number acquisition unit.
A holding unit that holds the sequence number of the packet acquired by the sequence number acquisition unit, and a holding unit.
The difference between the sequence number of the current packet acquired by the sequence number acquisition unit and the sequence number of the current packet predicted based on the sequence number of the immediately preceding packet received immediately before the current packet held by the holding unit. A deviation amount calculation unit that calculates a certain deviation amount, and a deviation amount calculation unit
A network quality calculation unit that estimates the packet order replacement rate based on the deviation amount calculated by the deviation amount calculation unit.
It is a network quality estimation device equipped with
The network quality calculation unit uses a deviation amount flag that sets "1" when the deviation amount is a negative value and "0" in other cases, and adds the deviation amount flag over a predetermined period to the cumulative deviation. The packet order replacement rate is defined as the value obtained by dividing the quantity flag by the number of packets to be received over the predetermined period calculated from the sequence number.
When the sequence number of the immediately preceding packet is the maximum sequence number that can be assigned to the packet, the deviation amount calculation unit does not perform a reset operation to reset the holding unit and the network quality calculation unit, and the current packet. The sequence number of the above is used as the deviation amount, and the network quality calculation unit has a negative deviation amount smaller than a predetermined negative threshold value before and after the negative deviation amount is calculated. A network quality estimation device, characterized in that, when a positive deviation amount for compensating for the negative deviation amount is not calculated within a fixed period shorter than the predetermined period, the negative deviation amount is replaced with 1.

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