JP2014216722A - Mobile network quality emulation apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve emulation of a mobile network.SOLUTION: A mobile network quality emulation apparatus includes: storage means for previously storing a plurality of emulation characteristic profiles of a steady packet transfer state and various state transition probability; emulation control means for emulating a plurality of transfer states of a packet by transiting the emulation characteristic profiles by dynamically applied probability; and profile changing means for changing the emulation characteristic profiles and the various state transition probability stored in the storage means at fixed distribution with the lapse of time. The mobile network quality emulation apparatus switches a plurality of profiles of a disconnection state in accordance with duration from a no communication state up to the disconnection state, and when the disconnection state is canceled, collectively transfers packets accumulated during connection delay time required up to transition to the steady packet transfer state.

Description

  The present invention relates to a mobile network quality emulation apparatus and method, and more particularly, to a mobile network quality emulation apparatus and method for a mobile network with high network quality fluctuation.

  Examples of the network emulation technology include SHUNRA (for example, see Non-Patent Document 1) and NISTNET (for example, see Non-Patent Document 2). SHUNRA measures the delay and packet loss of the real network and imports the measurement data into the emulator to emulate a real environment. Analyze performance degradation factors (for example, bandwidth, server, application, etc.) from emulation results.

  NISTNET is Linux (registered trademark) compatible network emulation software, and the Linux (registered trademark) server that operates as a router using this software has various functions such as congestion loss, packet reordering, and asymmetric bandwidth status. The network state can be emulated.

  As described above, the techniques of Non-Patent Documents 1 and 2 are basically designed for the purpose of emulation of a fixed line network. In mobile network emulation, factors such as network quality fluctuations must be taken into account.

SHUNRA http://www.shunra.com/products/shunra-nv-mobile NISTNET http://www-x.antd.nist.gov/nistnet/

  However, products such as the above SHUNRA are supposed to emulate mobile quality, but basically the parameters of the emulation mechanism of the conventional fixed line network are “Large delay / loss ratio”, “Distribution” Was set to "has fluctuation with time".

  The quality in mobile has the following characteristics, and there is a problem that it cannot be reproduced by an emulator for a fixed network.

<Characteristic>
The internal quality state has multiple independent discrete states;
・ If the no-communication state continues for a certain period of time (even if the upper layer remains connected), the lower layer connection is temporarily disconnected, and a certain connection delay occurs when sending side packets (for example, GSMA Smarter apps for Smarter phones , http://www.gsma.com/technicalporojects/wp-content/uploads/2012/04/gsmasmarterappsforsmarterphones0112.v.0.14.pdf etc.);
-Even during normal communication, the packets sent during the pseudo-connection disconnection after a certain connection delay (pseudo-connection disconnection recovery time) after a sudden disconnection ("pseudo-connection disconnection" state) Will be sent;
・ The above conditions change over time or get worse;
The present invention has been made in view of the above points.
The quality state inside the network has multiple independent discrete states;
-If the state during wireless communication continues for a certain period of time (even if the upper layer remains connected), the connection of the lower layer will be temporarily disconnected, and a certain connection delay will occur when sending the packet again;
-Even during normal communication, suddenly disconnection ("pseudo connection disconnection" state), packets sent during pseudo connection disconnection after a certain connection delay (pseudo connection disconnection recovery time) To be sent;
It is an object of the present invention to provide a mobile network quality emulation apparatus and method capable of reflecting the above on an emulation apparatus.

In order to solve the above problems, the present invention (Claim 1) is a mobile network quality emulation apparatus for performing quality emulation for a mobile network,
A plurality of emulation characteristic profiles in a steady packet transfer state in advance, storage means storing various state transition probabilities,
Emulation control means for emulating a plurality of transfer states of a packet by causing the emulation characteristic profile to transition dynamically with a probability given;
And a profile changing unit that changes the emulation characteristic profile of the storage unit and the various state transition probabilities with a constant distribution over time.

Further, the present invention (Claim 2) has a disconnection state transition means for transitioning to the “connection disconnection state” when the “state of no communication” continues for a predetermined time,
The disconnected state transition means includes:
Using the profile changing means, the plurality of profiles in the “connection disconnected state” are switched according to the duration from the “state without communication” to the “connection disconnected state”, and when the connection disconnected state is resolved, Means for collectively transferring packets accumulated in the connection delay time required until the transition to the steady packet transfer state;

The present invention (Claim 3) provides the emulation control means,
At the time of the first packet transfer, it includes means for temporarily setting a connection delay from the “connection disconnection state” and transitioning to a steady state.

The present invention (Claim 4) provides the emulation control means,
In the case of switching the internal quality state in the steady state, there is further provided means for calculating a state transition probability at regular time intervals and determining the state according to the state transition probability.

  As described above, according to the present invention, in a mobile network, the quality state inside the network has a plurality of independent discrete states, and when the wireless communication state continues for a certain period of time (even if the upper layer remains connected), the lower layer When a connection is disconnected once and a packet is sent again, a certain connection delay is applied. Even during normal communication, the pseudo connection is suddenly disconnected, and the pseudo connection is disconnected after a certain connection delay. It is possible to reflect in the emulation that the packets sent in between are sent together.

It is a block diagram of the network emulator in one embodiment of this invention. It is a state transition diagram in one embodiment of the present invention. It is a figure which shows the internal transition of the steady state in one embodiment of this invention. It is a state transition flow figure in one embodiment of the present invention. FIG. 6 is an internal state transition pattern (contents of “steady state” in FIG. 4) in a steady state according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a configuration of a network emulator according to an embodiment of the present invention.

  A network emulator 100 (hereinafter simply referred to as “emulator”) shown in FIG. 1 includes a plurality of packet input / output interfaces 10, a packet processing unit main body 20 that receives and forwards packets, a state transition control unit 30 having functions described later, It has a random number generation unit 40 that generates a random number when obtaining a connection delay, a timer unit 50 that measures the passage of time, and a state transition parameter storage unit 60.

  In the present invention, the following functions are added to the state transition control unit 30 in order to realize network emulation reflecting characteristics in the mobile network.

● Discrete state transition function:
Instead of a single distribution characteristic (for loss, delay, delay fluctuation, etc.), a plurality of independent emulation characteristic profiles are prepared for the steady packet transfer state, and they are transitioned with the probability given dynamically. To emulate multiple transfer states. In addition, the parameters of these profiles and the transition probabilities also change with a constant distribution over time.

● Connection disconnection and connection delay function without communication:
When the timer unit 50 detects that the “no communication” state continues for a predetermined time set in advance, the timer unit 50 transitions to the “disconnection” state, and the duration of the “no communication state” ( As the duration is increased), the connection disconnection state of the transition destination has a certain distribution until a transition to the steady packet transfer state occurs when a plurality of profiles are switched and packet communication occurs again (disconnection disconnection state). "Connection delay" takes time, packets in between are delayed, and when the connection is restored, they are transferred together.

● First connection delay function:
Since the connection delay from the disconnected state is necessary also at the time of the first packet transfer, the connection delay having a certain distribution is also taken into account.

● Delay function due to pseudo disconnection:
Since the disconnection occurs even in a state where the communication is continuously performed, a delay due to the “pseudo connection disconnection” is generated with a probability based on the set parameters even during the communication. This also has a mechanism in which packets in the meantime are delayed and transferred together when the connection is restored, just as when returning from a disconnected communication.

  The parameter storage unit 60 such as state transition stores parameters such as a transfer state profile set, various state transition probabilities, and a connection delay time probability distribution shown in the following (1) to (3). Details of the following setting parameters are shown.

(1) Transfer status profile set:
In order to realize discrete state transition, a plurality of sets of transfer state profiles are provided.

Number of transfer status levels: n
Number of stopped levels: m
Here, as an example, an example in which a set (S _A , S _B , S _C ) of n = 3 is defined is as follows. (The normal distribution and the like are not relevant except in this definition example, but when the normal distribution is taken, it is described as an example showing a specific example in which the accompanying parameters are two of average loss and variance).

・ Set A (S _A ):
Loss rate distribution: Normal distribution (S _{A, Lf} )
Parameters: Average loss rate (S _{a, la} ), variance (S _{A, lb} )
Delay distribution: Normal distribution (S _{A, Df} )
Parameters: Average delay (S _{A, da} ), variance (S _{A, db} )
Band:
Parameter: Band (S _{A, B} )
・ Set B (S _B ))
Loss rate distribution: Uniform distribution (S _{B, Lf} )
Parameters: Minimum loss rate (S _{B, la} ), Maximum loss rate (S _{B, lb} )
Delay distribution: exponential distribution + offset (S _{B, Df} )
Parameters: Offset value (minimum delay value: (S _{B, da} ), variance (S _{B, db} )
Band:
Parameter: Band (S _{B, B} )
・ Set C (S _c )
Loss rate distribution: Occurrence distribution (S _{C, Lf} )
Parameters: Average loss rate (S _{C, la} ), variance (S _{C, lb} )
Delay distribution: exponential distribution + offset (S _{c, Df} )
Parameters: Offset value (minimum delay value: S _{C, da} ), variance (S _{C, db} )
Band:
Parameter: Band (S _{C, B} )
The above parameters are functions that change over time except for the band (including the case where the time does not change over time).

(2) Various state transition probabilities:
-Steady state transition probability function Ps _ij (t) (i and j are subscripts representing states, and t is time)
Example) When in state A at time 5, the probability of switching to another state B or C is given as follows: Ps _AB (5), Ps _AC (5)
If there are three states, there are six transition probabilities of 3 × 2, which change with time (states that do not change may be expressed by a constant function: the ratio of bad states gradually increases with time) It is a function of time to emulate a simple state).

・ Pseudo disconnection state transition probability:
Pd _i (t) (i corresponds to states A, B, and C in the above example)
Naturally, the sum of the state transition probabilities of each state (A, B, C) at each time point (Σj Px _ij (t) + pd _i (t) is 1.0 or less) (i is any of A, B, C) Or Σj is the sum of j)
-State transition recalculation time: Z
(Calculate in the emulator whether the state changes for each Z, and change the state as necessary)
(3) Probability distribution of connection delay time • Connection delay time function (inverse function of cumulative distribution of probability density of connection delay time) is preset for each of m stop state levels (I = L1, L2,... Lm). .

C _l (r, t)
Here, for example, the function of “connection delay at time t in L1 state” is given by C _L1 (r, t),
Input: t = time (0 to infinity)
r = random number (0-1)
It is. That is, the connection delay (when the result of random number calculation is 0.4 in the state of time 5 in the L1 state) is
Output: C _L1 (0.4, 5)
As given.

・ State transition time when there is no communication:
When the non-communication time continues for this time, the state transits to each stop state step by step.

T _I (However, I = L1, L2… Lm)
・ The pseudo disconnection time is given below.

C _R (r, t)
Input: t = time (0 to infinity)
r = random number (0-1)
Below, the operation | movement in the state transition control part 30 is demonstrated based on FIG.

  The actual operation starts from the initial state of the state transition diagram of FIG. 2 and goes through a first connection delay calculation process to a steady communication state (hereinafter simply referred to as “steady state”). The state transition in the steady state transitions based on the probability of state transition (state transition probability). Specifically, a random number is assigned by the random number generation unit 40 at regular time intervals, and a state transition is made if a predetermined threshold is exceeded. In the steady state, the (existing) network emulator mechanism operates with parameters such as packet loss distribution, delay distribution, and bandwidth set in the parameter storage unit 60 such as state transition. As shown in FIG. 3, the internal transition in the steady state holds the following distributions as parameters for each state (states S1, S2, S3).

・ Transfer delay distribution (the distribution function changes with time)
Loss rate (time dependent)
・ Band (Time independent)
・ Probability of transition to pseudo disconnection state (time-dependent)
・ Pseudo disconnection duration distribution in the case of a pseudo disconnection state (time dependent)
In the internal transition in the steady state, the probability of transition to which state is determined for each original state, and the transition state is selected based on the probability.

  In addition, the internal state transition and the occurrence of pseudo disconnection are periodically emulated every time Z, and when it is detected by the timer unit 50 that no communication time without packet communication has elapsed, When the packet is sent there, the state transition that connection delay occurs is repeated.

  The details and specific operation of this state transition will be individually described below with reference to FIG.

[1] Transition to the stop state when there is no communication:
In the communication state, when no communication has elapsed for _TL1 time since the last packet passed for either transmission or reception,
Transition from [Communication state] to [Stop state level L1].

After that, if no additional packet transmission / reception occurs even after an additional _TL2 time,
Transition is made from [stop state level L1] to [stop state level 2], and the final stop state level Lm remains in that state until the next communication occurs without a state timer.

  At the stage of communication (when a packet is first input), the connection delay corresponding to each stop state level is calculated, and the content of “control in connection delay & pseudo connection disconnection state” in [2] is calculated with the delay time. Move.

[2] Control in connection delay & pseudo connection disconnection In connection with packet processing, since connection delay and pseudo connection disconnection are the same processing, they are described collectively.

  Although it is close to “disconnected state”, emulation is not possible in the disconnected state (= packet is discarded), and the received packets are accumulated without discarding, and “reconnect” It is necessary to send out the accumulated packets when returning to the state.

  Although a new implementation may be added by emulation, here, a method for realizing it using the delay control of an existing network emulator is shown.

  FIG. 4 shows a state transition flow.

First, when “connection delay” or “pseudo-connection disconnection state” is reached, “reconnection required time” is determined from the probability distribution of connection delay time corresponding to each state (for example, state transition control unit 30 Determines the delay time from the distribution form given at that time using the random number generated by the random number generation unit 40. For example, when the stop state L1 is reached at time 53, a random number is assigned. If the result is 0.3, the reconnection time is C _L1 (0.3, 53).

Similarly, when the pseudo connection is cut off at time 53, if the result of assigning random numbers is 0.3, the reconnection delay is C _R (0.3, 53).

  This calculated delay time is denoted by τ.

  First, let the time length of the connection delay pipe of the emulator 100 be τ, and then gradually set the delay time to be linearly smaller until τ elapses (the delay setting time is also τ-1 after τ-1). So that the delay becomes 0 after τ.

  If there is a mechanism that changes the delay time setting completely continuously, it can be used if it exists in the original emulator, and the length of the connection delay pipe can be adjusted in sufficiently fine time units even if it does not exist. The delay set time may be subtracted by the amount of time that has passed after a certain time has elapsed.

  In the pseudo connection disconnection state, when the delay time becomes zero when τ elapses, the accumulated packets are sent all at once, and the connection delay becomes the pseudo connection disconnection state returns to the “steady state”.

  In the stopped state L1, L2... L (m-1), after waiting for the first packet, the packet delay processing is performed in the same manner as described above.

The first packet waiting process is set as a waiting time for T ₁ (for example, T _{L1 for L1} ) corresponding to each stop state. If “the first packet (after moving to that state)” arrives within the time of T _I , the process proceeds to the delay process in the connection delay pipe of τ described above.

If there is no packet within the time of T _I , the transition to the above-described delay subtraction mode is not made, and the state is shifted to the next higher state (if L1, the next L2 level).

If it is in the stop state Lm (the highest stop state), it will wait indefinitely until the “next packet” arrives, and “connection delay” by C _Lm () after the first packet arrives.

[3] Transition of internal quality state in steady state In a normal packet transfer state, as shown in FIG. 5, there are a plurality of steady state internal states (for example, when n = 3, S _A , S _B , S 3 types of _C), in a steady state to be put with its one.

  In this state switching, the state transition probability is calculated every certain time Z. When transitioning from the initial state or the disconnected state to the steady state (via connection delay), the first state is determined by a random number.

  The first state (assuming that the user is in state A) calculates which state is in the state transition probability from state A.

Ps _AB (0) = 0.2, Ps _AC (0) = 0.1, Pd _A (0) = 0.05
If the random number r in the interval 0 to 1 is 0.0 ≦ r <0.2, the state transitions to the state B. If the random number r in the interval 0 to 1 is 0.2 ≦ r <(0.2 + 0.1), When the transition to the state C and the random number r in the sections 0 to 1 is 0.3 ≦ r <(0.3 + 0.05), the transition is made to the pseudo connection disconnection state, and otherwise, the transition is made to the state A. That is, for example, when r = 0.2, the state C is selected.

  Thereafter, a similar state transition probability is calculated every certain time Z, and it is determined whether the state transitions to another state or remains in the original state.

In each state, network quality state emulation is performed according to the packet loss probability distribution and set bandwidth determined by set A (S _A ) etc. (Because emulation in each state is within the scope of existing technology, here (No details will be mentioned).

  Note that the packet loss probability distribution and delay probability distribution change at the same time as processing for each time Z for state switching (due to time changes), so update the settings to the packet loss probability distribution and delay probability distribution at that time . As a result, the time change is realized in a pseudo manner while using a network emulator that does not support the time change such as loss distribution.

  The operation of each component of the network emulator shown in FIG. 1 can be constructed as a program, installed in a computer used as a network emulator, executed, or distributed via a network.

  The present invention is not limited to the above-described embodiment, and various modifications and applications can be made within the scope of the claims.

DESCRIPTION OF SYMBOLS 10 Packet input / output interface 20 Packet processing part main body 30 State transition control part 40 Random number generation part 50 Timer part 60 Parameter storage part, such as state transition

Claims (8)

A mobile network quality emulation device that performs quality emulation for a mobile network,
A plurality of emulation characteristic profiles in a steady packet transfer state in advance, storage means storing various state transition probabilities,
Emulation control means for emulating a plurality of transfer states of a packet by causing the emulation characteristic profile to transition dynamically with a probability given;
The emulation characteristic profile of the storage means, profile changing means for changing the various state transition probabilities with a constant distribution over time;
A mobile network quality emulation apparatus comprising: When there is a “no communication” state for a predetermined time, it has a disconnection state transition means for transitioning to a “connection disconnection state”.
The disconnected state transition means includes:
Using the profile changing means, the plurality of profiles in the “connection disconnected state” are switched according to the duration from the “state without communication” to the “connection disconnected state”, and when the connection disconnected state is resolved, 2. The mobile network quality emulation device according to claim 1, further comprising means for collectively transferring packets accumulated in the connection delay time required until the transition to the steady packet transfer state. The emulation control means includes
2. The mobile network quality emulation apparatus according to claim 1, further comprising means for temporarily setting a connection delay from the “connection disconnection state” and transitioning to a steady state at the time of initial packet transfer. The emulation control means includes
2. The mobile network quality emulation apparatus according to claim 1, further comprising means for calculating a state transition probability at regular time intervals and determining a state according to the state transition probability when switching the internal quality state in the steady state. A mobile network quality emulation method for performing quality emulation for a mobile network,
A plurality of emulation characteristic profiles in a steady packet transfer state in advance, storage means storing various state transition probabilities,
Emulation control means;
A device having profile change means,
An emulation control step in which the emulation control means emulates a plurality of transfer states of a packet by causing the emulation characteristic profile to transition dynamically with a probability given;
The profile changing means changes the emulation characteristic profile of the storage means, the various state transition probabilities with a constant distribution over time, and
A mobile network quality emulation method characterized by: If the “no communication” state continues for a predetermined time, a connection disconnection state transition step for transitioning to the “connection disconnection state” is further performed,
In the disconnected state transition step,
Calling the profile change step, switching a plurality of profiles in the “connection disconnected state” according to the duration from the “state without communication” to the “connection disconnected state”, when the connection disconnected state is resolved, 6. The mobile network quality emulation method according to claim 5, wherein the packets accumulated in the connection delay time required until the transition to the steady packet transfer state is transferred together. In the emulation control step,
6. The mobile network quality emulation method according to claim 5, wherein, at the time of the first packet transfer, the connection delay is temporarily set from the “connection disconnection state” and a transition is made to a steady state. In the emulation control step,
6. The mobile network quality emulation method according to claim 5, wherein, when switching the internal quality state in the steady state, the state transition probability is calculated at regular intervals, and the state is determined according to the state transition probability.

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