THROUGHPUT ESTIMATION DEVICE TECHNICAL FIELD [0001] The present invention relates to throughput estimation devices estimating throughput. BACKGROUND ART [0002] When a transmitting device sends a data to a receiving device, there are cases that because some part of the data is lost (has disappeared), only the other part of the data arrives at the receiving device. Further, when the transmitting device sends a data to the receiving device, there are cases that because some part of the data is accumulated within the communication network, the arrival of the data at the receiving device is too late (the delay time, which is the time from the transmitting device sending the data to the data arriving at the receiving device, becomes too long). [0003] Among the data sent by the transmitting device, the amount of the data (the data arrival amount) having arrived at (or being received by) the receiving device per unit time is called throughput. [0004] For example, if the transmitting device sends a data to the receiving device at a transmission rate of 4 Mbps, then it is assumed that 25% of the data (that is, a part corresponding to 1Mbps) is lost. Here, the transmission rate is the amount of the data sent by the transmitting device per unit time. In this case, the receiving device receives the data at 3Mbps. That is, the throughput is 3Mbps. [0005] Further, even if no data is lost, it is still assumed that the receiving device receives the data at 3Mbps because of the increase in delay time. In this case, the throughput is also 3Mbps. [0006] If the data sent from the transmitting device to the receiving device is multimedia data such as video and/or audio data, then any loss of the data may cause noise to occur in the video and/or audio. Further, an excessive delay time may possibly bring a stop to the play of the video and/or audio. [0007] Therefore, it is considered as preferable to estimate the throughput with a high accuracy, and adjust the data size of the multimedia data sent by the transmitting device based on the estimated throughput. Hence, techniques for estimating the throughput are being developed. The throughput estimation devices disclosed in the following Patent Document 1 through Patent Document 6 are known as such kind of techniques. [0008] Patent Document 1: Pamphlet of WO 08/143026 Patent Document 2: JP 2004-254025 A Patent Document 3: JP 2005-244851 A Patent Document 4: JP 2007-116329 A Patent Document 5: JP 2008-258877 A Patent Document 6: JP 2008-278207 A [0009] However, such a case can be assumed as to apply the above throughput estimation devices to a mobile communication system in which a mobile station (a receiving device) and a transmitting device are communicably connected via a wireless link established between the mobile station and a base station on a mobile communication network. [0010] In this case, even for a constant transmission rate, the data transmission rate through the wireless link still changes with any change in the quality of the wireless link (the wireless link quality). As a result, the throughput also changes. Here, the data transmission rate is the amount of the data transmitted per unit time through the wireless link. [0011] Referring to Figs. 1A to 1C, the throughput change with the change in the wireless link quality will be explained in more detail. The pipes in Figs. 1A to 1C denote a wireless link. Figs. 1A to 1C show that the thicker the pipe, the higher the data transmission rate through the wireless link (i.e. the higher the wireless link quality). [0012] The arrows entering in the pipe denote the transmission rate. Figs. 1A to 1C show that the more the number of the arrows entering in the pipe, the higher the transmission rate. Further, the arrows exiting from the pipe denote the throughput. Figs. 1A to 1C show that the more the number of the arrows exiting from the pipe, the higher the throughput. [0013] Fig. 1A shows that both the wireless link quality and the throughput are at the highest level. Fig. IB shows that both the wireless link quality and the throughput are at the lowest level. Fig. 1C shows that both the wireless link quality and the throughput are at the second highest level. In this manner, the throughput also changes with the change in the wireless link quality. [0014] However, the above throughput estimation devices estimate the throughput without being based on the wireless link quality. Therefore, it is liable to be unable to estimate the throughput with a high accuracy when the data is sent via the wireless link. SUMMARY [0015] Hence, an exemplary object of the present invention is to provide a throughput estimation device capable of solving the above problem of "being unable to estimate the throughput with a high accuracy when the data is sent via the wireless link". [0016] In order to achieve this exemplary object, an aspect of the present invention provides a throughput estimation device including: a wireless link quality information acquisition means for acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and a throughput estimation means for estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. [0017] Further, another aspect of the present invention provides a throughput estimation method including: acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. [0018] Further, still another aspect of the present invention provides a throughput estimation computer program including instructions for causing an information processing device to carry out a process including the steps of: acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. [0019] Because the present invention is configured in the manner as described above, it is possible to estimate the throughput with a high accuracy when the data is sent via the wireless link. BRIEF DESCRIPTION OF DRAWINGS [0020] Figs. 1A to 1C are explanatory diagrams conceptually showing a change in the throughput with a change in the wireless link quality; Fig. 2 shows a schematic configuration of a mobile communication system in accordance with a first exemplary embodiment of the present invention; Fig. 3 is a block diagram showing a schematic function of the mobile communication system in accordance with the first exemplary embodiment of the present invention; Fig. 4 is a graph showing an example of the changes with time in transmission rate and throughput when a transmitting device sends data to a receiving device via a wireless link; Fig. 5 is a graph showing the change with time in the value of wireless link quality; Fig. 6 is a graph showing a correlation between the variation in the value of wireless link quality and the variation in throughput; Fig. 7 is a graph showing an example of the respective changes with time in the estimated value of throughput, measured value of throughput, and smoothed CQI; Figs. 8A to 8C are explanatory diagrams conceptually showing an influence exerted by cross-traffic on the throughput; Fig. 9 is an explanatory diagram conceptually showing a dynamic model in accordance with a second exemplary embodiment of the present invention; Fig. 10 is an explanatory diagram conceptually showing a dynamic model in accordance with a modification of the second exemplary embodiment of the present invention; Fig. 11 is an explanatory diagram conceptually showing a dynamic model in accordance with another modification of the second exemplary embodiment of the present invention; Fig. 12 is a block diagram showing a schematic function of a mobile communication system in accordance with the second exemplary embodiment of the present invention; Fig. 13 is an explanatory diagram conceptually showing the contents of simulations in accordance with the second exemplary embodiment of the present invention; Fig. 14 is a graph showing a pattern of the transmission rate used in the simulations in accordance with the second exemplary embodiment of the present invention; Fig. 15 is a graph showing a change with time in the value of wireless link quality in a first simulation in accordance with the second exemplary embodiment of the present invention; Fig. 16 is a graph showing a change with time in the value of wireless link quality in a second simulation in accordance with the second exemplary embodiment of the present invention; Fig. 17 is a graph showing a change with time in the value of wireless link quality in a third simulation in accordance with the second exemplary embodiment of the present invention; Fig. 18 is a graph showing a change with time in the value of wireless link quality in a fourth simulation in accordance with the second exemplary embodiment of the present invention; Fig. 19 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput in the first simulation in accordance with the second exemplary embodiment of the present invention; Fig. 20 is a graph showing the respective changes with time in the measured value of loss rate and estimated value of loss rate in the first simulation in accordance with the second exemplary embodiment of the present invention; Fig. 21 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput in the second simulation in accordance with the second exemplary embodiment of the present invention; Fig. 22 is a graph showing the respective changes with time in the measured value of loss rate and estimated value of loss rate in the second simulation in accordance with the second exemplary embodiment of the present invention; Fig. 23 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput in the third simulation in accordance with the second exemplary embodiment of the present invention; Fig. 24 is a graph showing the respective changes with time in the measured value of loss rate and estimated value of loss rate in the third simulation in accordance with the second exemplary embodiment of the present invention; Fig. 25 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput in the fourth simulation in accordance with the second exemplary embodiment of the present invention; Fig. 26 is a graph showing the respective changes with time in the measured value of loss rate and estimated value of loss rate in the fourth simulation in accordance with the second exemplary embodiment of the present invention; and Fig. 27 is a block diagram showing a schematic function of a throughput estimation device in accordance with a third exemplary embodiment of the present invention. EXEMPLARY EMBODIMENTS [0021] Hereinbelow, referring to Figs. 1 through 27, explanations will be made with respect to each exemplary embodiment of a throughput estimation device, a throughput estimation method and a throughput estimation computer program in accordance with the present invention. [0022] (k) and 8 are three-dimensional column vectors, respectively. [Formula 9] [Formula 10] [0098] Formula 8, which is a difference equation, can be expressed as shown in Formula 11 by using q>(k) and 0. [Formula 11] [0099] According to Formula 11, it is possible to apply the least-squares estimation method to 9. By letting the 0 estimated by the least-squares estimation method be 0e, it is possible to find 9e by the following Formula 12. Here, S(x) denotes the value of summating X for k (that is, the summation of X for every calculation period h). Further, X"1 denotes the inverse matrix of the matrix X. [Formula 12] [0100] Then, by letting the estimated 0e be 0e = [0i, 02, Q3], the model parameters D, a, and b can be found by Formula 13, Formula 14, and Formula 15, respectively. [Formula 13] [Formula 14] [Formula 15] [0101] Further, as shown in Fig. 12, the function of the transmitting device 100 in accordance with the second exemplary embodiment includes a transmission rate acquisition portion (transmission rate acquisition means) 102, in addition to the function of the transmitting device 100 in accordance with the first exemplary embodiment. [0102] Each time the calculation period h passes over, the transmission rate acquisition portion 102 calculates (acquires) the transmission rate which is the amount (size) of the data sent by the data transmission portion 101 to the receiving device 200 per unit time. [0103] Then, the model parameter estimation portion 105 in accordance with the second exemplary embodiment calculates (estimates) the model parameters by using the least-squares estimation method as described before, based on the wireless link quality information (the smoothed CQI in this example) q(k) acquired by the wireless link quality information acquisition portion 104, the throughput (the estimated value of throughput) v(k) acquired by the reception rate acquisition portion 103, the transmission rate u(k) acquired by the transmission rate acquisition portion 102, and the aforementioned hybrid model. [0104] Further, the throughput estimation portion 106 in accordance with the second exemplary embodiment estimates the throughput based on the mathematical model (hybrid model) specified by the model parameters estimated by the model parameter estimation portion 105, the wireless link quality information acquired by the wireless link quality information acquisition portion 104, and the transmission rate acquired by the transmission rate acquisition portion 102. In this example, the throughput estimation portion 106 estimates the throughput based on Formula 8. [0105] As explained hereinabove, according to the transmitting device (throughput estimation device) 100 in accordance with the second exemplary embodiment of the present invention, it is possible to realize a similar function and effect to that of the transmitting device 100 in accordance with the first exemplary embodiment. Further, the transmitting device 100 in accordance with the second exemplary embodiment estimates the throughput based on the mathematical model constructed by denoting the relation between the transmission rate and the throughput based on a dynamic model. By virtue of this, it is possible to estimate the throughput with an even higher accuracy when cross-traffic is present. [0106] In addition, the transmitting device 100 in accordance with the second exemplary embodiment estimates the throughput based on the mathematical model constructed by denoting the relation between the transmission rate and the throughput based on a dynamic model including an elastic body and a viscous body. [0107] Now, the elastic force of the elastic body denotes better the change of the transmission rate related to the cross-traffic, arising from the change of the transmission rate related to the self-traffic. Further, delay time is necessary from the transmitting device 100 changing the transmission rate related to the self-traffic to changing the transmission rate related to the cross-traffic. The resisting force of the viscous body denotes this delay time better. Therefore, according to the transmitting device 100 in accordance with the second exemplary embodiment, it is possible to estimate the throughput with an even higher accuracy when cross-traffic is present. [0108] Next, the effect of the transmitting device 100 in accordance with the second exemplary embodiment will be explained more specifically through the results of the following simulations. [0109] Fig. 13 is an explanatory diagram conceptually showing the contents of the simulations. In the simulations, a plurality of (in this example, 12) users Rl to R4 and CI to C8 each hold one of mutually different receiving devices 200. [0110] Each of the users Rl to R4 holds the receiving device 200 as the object of estimating the throughput. The user Rl is walking at a position 100 m away from the base station BS. The user R2 is walking at a position 300 m away from the base station BS. The user R3 rides in a car running at a position 300 m away from the base station BS. The user R4 rides in a car running at a position 500 m away from the base station BS. [0111] Further, each of the users CI to C8 holds the receiving device 200 receiving the cross-traffic. The user CI is positioned in a building 100 m away from the base station BS. The user C2 is positioned in a building 300 m away from the base station BS. The user C3 is positioned in a building 500 m away from the base station BS. [0112] The user C4 is walking at a position 700 m away from the base station BS. The user C5 rides in a car running at a position 700 m away from the base station BS. The user C6 rides in a car running at another position 700 m away from the base station BS. The user C7 is walking at a position 1000 m away from the base station BS. The user C8 is positioned in a building 1000 m away from the base station BS. [0113] In this case, the longer the distance between the receiving device 200 and the base station BS, the worse (the lower) the wireless link quality. Further, the users who ride in moving cars have a lower wireless link quality than the users who are walking. [0114] Further, in the simulations, the transmitting device 100 sent a data at a transmission rate with a preset pattern to each of the receiving devices 200 held by the users Rl to R4 via the base station BS. [0115] As shown in Fig. 14, the pattern is a rectangular wave which alternately repeats 0 Mbps and 0.6 Mbps for every ten minutes (0.8 Mbps only for the transmission to the receiving device 200 held by the user R2). [0116] Further, the cross-traffic is sent according to FTP (File Transfer Protocol)/TCP. In this example, the cross-traffic is a traffic involving file download. [0117] This time, four simulations were carried out. In the first simulation, the receiving device 200 held by the user Rl is the object of estimating the throughput, and the cross-traffic is sent only to each of the receiving devices 200 held by the users CI to C5. In the second simulation, the receiving device 200 held by the user R2 is the object of estimating the throughput, and the cross-traffic is sent only to each of the receiving devices 200 held by the users CI to C3. [0118] In the third simulation, the receiving device 200 held by the user R3 is the object of estimating the throughput, and the cross-traffic is sent only to each of the receiving devices 200 held by the users CI to C3. In the fourth simulation, the receiving device 200 held by the user R4 is the object of estimating the throughput, and the cross-traffic is sent only to each of the receiving devices 200 held by the users C1 to C3. [0119] Then, for each of the four simulations, the transmitting device 100 estimates the model parameters based on the acquired throughput (the estimated value of throughput), the acquired wireless link quality information (the smoothed CQI), and the mathematical model (hybrid model). [0120] Further, for each of the four simulations, the transmitting device 100 estimates the throughput based on the mathematical model (hybrid model) specified by the estimated model parameters, the transmission rate, and the acquired wireless link quality information (the smoothed CQI). [0121] Fig. 15 is a graph showing a change with time in the value of wireless link quality (CQI in this example) denoting the quality of the wireless link established between the base station BS and the receiving device 200 held by the user Rl. The CQI for the receiving device 200 held by the user Rl is vary high, and varies vary little with time (being very stable). [0122] Fig. 16 is a graph showing a change with time in the value of wireless link quality denoting the quality of the wireless link established between the base station BS and the receiving device 200 held by the user R2. The CQI for the receiving device 200 held by the user R2 is comparatively high, and varies comparatively little with time (being comparatively stable). [0123] Fig. 17 is a graph showing a change with time in the value of wireless link quality denoting the quality of the wireless link established between the base station BS and the receiving device 200 held by the user R3. The CQI for the receiving device 200 held by the user R3 varies very greatly with time (being unstable), and its average value is about the same as that of the receiving device 200 held by the user R2. [0124] Fig. 18 is a graph showing a change with time in the value of wireless link quality denoting the quality of the wireless link established between the base station BS and the receiving device 200 held by the user R4. The CQI for the receiving device 200 held by the user R4 is very low, and varies very greatly with time (being unstable). That is, it can be said that this wireless link is very unstable. [0125] Fig. 19 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput (the throughput estimated by the transmitting device 100), in the first simulation. As shown in Fig. 15, because the value of wireless link quality is stable at a high value, the throughput is mainly under the influence of cross-traffic. [0126] If the transmission rate is increased in a step-like manner (i.e., discontinuously), then with respect to the change of the transmission rate, the change of the throughput delays as long as the time required to push away the cross-traffic. That is, as shown in Fig. 19, the initial rise of the throughput draws a curve. The estimated value of the throughput is successfully reflecting this curve drawn by the measured value of the throughput. [0127] Further, if the transmission rate is increased in a step-like manner, then even after the delay time is over, it is still impossible to push away all cross-traffic. That is, as shown in Fig. 19, the maximum value of the throughput is less than the maximum value of the transmission rate. The estimated value of the throughput is successfully reflecting that the maximum measured value of the throughput is less than the maximum value of the transmission rate. [0128] In this manner, the transmitting device 100 can estimate the throughput with a high accuracy by using the hybrid model. [0129] Fig. 20 is a graph showing the respective changes with time in the measured value of loss rate (packet loss rate) and estimated value of loss rate (the loss rate calculated based on the throughput estimated by the transmitting device 100), in the first simulation. In this manner, the transmitting device 100 can also estimate the loss rate with a high accuracy by using the hybrid model. [0130] Fig. 21 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput in the second simulation. As shown in Fig. 16, because the value of wireless link quality varies to some extent, the throughput is also under a comparatively great influence of the wireless link quality in addition to the cross-traffic. [0131] The influence exerted by the wireless link quality on the throughput is seen to be strong especially in the period of 10 to 20 seconds. During the period of 10 to 20 seconds, because the value of wireless link quality is comparatively low, the throughput is also comparatively low. On the other hand, during the period after 30 seconds, because the value of wireless link quality is stable at a comparatively high value, the throughput changes in the same manner as in the first simulation. [0132] In this manner, in the second simulation, the throughput is under a comparatively great influence of both the wireless link quality and the cross-traffic. As shown in Fig. 21, in such case, too, the transmitting device 100 can still estimate the throughput with a high accuracy by using the hybrid model. [0133] Fig. 22 is a graph showing the respective changes with time in the measured value of loss rate and estimated value of loss rate in the second simulation. In this manner, the transmitting device 100 can estimate the loss rate with a high accuracy by using the hybrid model, including the rapid increase in loss rate during the period of 10 to 20 seconds. [0134] Fig. 23 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput in the third simulation. As shown in Fig. 17, because the value of wireless link quality varies very greatly, the throughput is under a comparatively great influence of the wireless link quality. [0135] During the period of 10 to 20 seconds, and during the period of 50 to 60 seconds, there is a time when the wireless link quality decreases comparatively greatly. Due to this influence, there is a time when the throughput also decreases comparatively greatly. On the other hand, during the period of 30 to 40 seconds, because the wireless link quality is comparatively high, the throughput is mainly under the influence of the cross-traffic. [0136] Thus, in the third simulation, the throughput is also under a comparatively great influence of both the wireless link quality and the cross-traffic. As shown in Fig. 23, in such case, too, the transmitting device 100 can still estimate the throughput with a high accuracy by using the hybrid model. [0137] Fig. 24 is a graph showing the respective changes with time in the measured value of loss rate and estimated value of loss rate in the third simulation. In this manner, the transmitting device 100 can estimate the loss rate with a high accuracy by using the hybrid model, including the packet loss occurring when the wireless link quality decreases greatly. [0138] Fig. 25 is a graph showing the respective changes with time in the transmission rate, measured value of throughput, and estimated value of throughput in the fourth simulation. As shown in Fig. 18, because the value of wireless link quality varies very greatly, the throughput is under a comparatively great influence of the wireless link quality. [0139] During the period when the wireless link quality is low, the throughput is also low. Thus, in the fourth simulation, the throughput is also under a comparatively great influence of both the wireless link quality and the cross-traffic. As shown in Fig. 25, in such case, too, the transmitting device 100 can still estimate the throughput with a high accuracy by using the hybrid model. [0140] Fig. 26 is a graph showing the respective changes with time in the measured value of loss rate and estimated value of loss rate in the fourth simulation. In this manner, the transmitting device 100 can estimate the loss rate with a high accuracy by using the hybrid model, including the packet loss occurring when the wireless link quality decreases greatly. [0141] In the above manner, from the simulation results, too, it becomes obvious that the transmitting device 100 in accordance with the second exemplary embodiment can estimate the throughput with a high accuracy when a data is sent via the wireless link when cross-traffic is present. [0142] Further, while the mathematical model in the second exemplary embodiment is constructed by expressing the relationship between the throughput, the wireless link quality information, and the transmission rate based on a dynamic model, it may also be constructed by expressing this relationship based on another model (such as a thermal conduction model, fluid model, circuit model, or the like). [0143] The whole or part of the exemplary embodiments disclosed above can be described as, but not limited to, the following supplementary notes. [0151] (Supplementary Note 1) A throughput estimation device comprising: a wireless link quality information acquisition means for acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and a throughput estimation means for estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. [0152] According to this throughput estimation device, it is possible to estimate the throughput with a high accuracy when a data is sent via the wireless link. [0153] (Supplementary Note 2) The throughput estimation device according to Supplementary Note 1, wherein the throughput estimation means is configured to estimate the throughput based on a mathematical model denoting a relationship between the throughput and the wireless link quality information, and on the acquired wireless link quality information. [0154] (Supplementary Note 3) The throughput estimation device according to Supplementary Note 2, wherein the mathematical model is constructed by assuming equality between the throughput and a polynomial function with the wireless link quality information as a variable. [0155] Now, there is a comparatively strong correlation between the throughput and the polynomial function with the wireless link quality information as a variable. Therefore, by configuring the throughput estimation device in the above manner, it is possible to estimate the throughput with an even higher accuracy when a data is sent via the wireless link. [0156] (Supplementary Note 4) The throughput estimation device according to Supplementary Note 3, wherein the mathematical model is constructed by assuming equality between the throughput and a linear function with the wireless link quality information as a variable. [0157] Now, there is a comparatively strong correlation between the throughput and the linear function with the wireless link quality information as a variable. Therefore, by configuring the throughput estimation device in the above manner, it is possible to estimate the throughput with an even higher accuracy when a data is sent via the wireless link. [0158] (Supplementary Note 5) The throughput estimation device according to Supplementary Note 2, further comprising a transmission rate acquisition means for acquiring a transmission rate which is the amount of the data sent by the transmitting device to the mobile station per unit time, wherein the throughput estimation means is configured to estimate the throughput based on the mathematical model denoting the relationship between the throughput, the wireless link quality information and the transmission rate, on the acquired transmission rate, and on the acquired wireless link quality information. [0159] If the communication bandwidth used by self-traffic changes, then the transmission rate for cross-traffic also changes. Here, the self-traffic is the data sent from the transmitting device to the mobile device. Further, the cross-traffic is the data sent by using a communication pathway sharing at least part of a pathway with the communication pathway from the transmitting device to the mobile station. [0160] Now, there is a comparatively strong correlation between the throughput, wireless link quality information and transmission rate for the self-traffic. Therefore, by configuring the throughput estimation device in the above manner, it is possible to estimate the throughput with an even higher accuracy when the cross-traffic is present. [0161] (Supplementary Note 6) The throughput estimation device according to Supplementary Note 5, wherein the mathematical model is expressed by an ordinary differential equation for the throughput with an inhomogeneous term of a function taking each of the transmission rate and the wireless link quality information as its variable. [0162] (Supplementary Note 7) The throughput estimation device according to Supplementary Note 6, wherein the inhomogeneous term is a product of the transmission rate and the polynomial function with the wireless link quality information as a variable. [0163] (Supplementary Note 8) The throughput estimation device according to Supplementary Note 7, wherein the inhomogeneous term is a product of the transmission rate and the linear function with the wireless link quality information as a variable. [0164] (Supplementary Note 9) The throughput estimation device according to any one of Supplementary Notes 5 to 8, wherein the mathematical model is constructed by expressing the relationship between the throughput, the wireless link quality information and the transmission rate based on a dynamic model. [0165] Now, the dynamic model successfully expresses the relationship between the throughput, the wireless link quality information and the transmission rate for the self-traffic. Therefore, by configuring the throughput estimation device in the above manner, it is possible to estimate the throughput with an even higher accuracy when the cross-traffic is present. [0166] (Supplementary Note 10) The throughput estimation device according to Supplementary Note 9, wherein the dynamic model comprises a mobile body movable in a preset moving direction; and at least one of an elastic body deforming in the moving direction as much as the displacement of the mobile body in the moving direction, and a viscous body delaying the movement of the mobile body in the moving direction. [0167] Now, the elastic force of the elastic body denotes better the change of the transmission rate related to the cross-traffic, arising from the change of the transmission rate related to the self-traffic. Therefore, by configuring the throughput estimation device in the above manner, it is possible to estimate the throughput with an even higher accuracy when the cross-traffic is present. [0168] Further, delay time is necessary from the transmitting device changing the transmission rate related to the self-traffic to changing the transmission rate related to the cross-traffic. The resisting force of the viscous body denotes this delay time better. Therefore, by configuring the throughput estimation device in the above manner, it is possible to estimate the throughput with an even higher accuracy when the cross-traffic is present. [0169] (Supplementary Note 11) The throughput estimation device according to Supplementary Note 10, wherein the mathematical model is constructed by assuming that an external force applied to the mobile body in the moving direction is as great as in accordance with the transmission rate and the wireless link quality information, and by assuming that the throughput is the distance in the moving direction between a preset reference position and the position of the mobile body. [0170] (Supplementary Note 12) The throughput estimation device according to Supplementary Note 11, wherein the mathematical model is constructed to let the inhomogeneous term express the external force. [0171] (Supplementary Note 13) The throughput estimation device according to any one of Supplementary Notes 10 to 12, wherein the mathematical model is constructed by assuming that an elastic force generated by the elastic body is as great as the value of the displacement of the mobile body from a force-free position which is the position of the mobile body with the elastic force being zero, multiplied by an elastic coefficient which is a proportionality coefficient, and the elastic force acts in the opposite direction to the direction in which the mobile body has moved from the force-free position. [0172] (Supplementary Note 14) The throughput estimation device according to any one of Supplementary Notes 10 to 13, wherein the mathematical model is constructed by assuming that a resisting force generated by the viscous body is as great as the velocity of the mobile body moving in the moving direction, multiplied by a viscosity coefficient which is another proportionality coefficient, and the resisting force acts in the opposite direction to the direction in which the mobile body moves. [0173] (Supplementary Note 15) The throughput estimation device according to any one of Supplementary Notes 1 to 14, further comprising: a throughput acquisition means for acquiring the throughout, and a model parameter estimation means for estimating a model parameter for specifying the mathematical model, based on the acquired throughput and the acquired wireless link quality information. [0174] (Supplementary Note 16) The throughput estimation device according to any one of Supplementary Notes 1 to 15, wherein the wireless link quality information is a value based on a channel quality indicator (CQI). [0175] (Supplementary Note 17) The throughput estimation device according to Supplementary Note 16, wherein the wireless link quality information is a value of having put the channel quality indicator through a smoothing process. [0176] (Supplementary Note 18) A throughput estimation method comprising: acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. [0177] (Supplementary Note 19) The throughput estimation method according to Supplementary Note 18, wherein the throughput is estimated based on a mathematical model denoting a relationship between the throughput and the wireless link quality information, and on the acquired wireless link quality information. [0178] (Supplementary Note 20) The throughput estimation method according to Supplementary Note 19, wherein the mathematical model is constructed by assuming equality between the throughput and a polynomial function with the wireless link quality information as a variable. [0179] (Supplementary Note 21) The throughput estimation method according to Supplementary Note 19, further comprising acquiring a transmission rate which is the amount of the data sent by the transmitting device to the mobile station per unit time, wherein the throughput is estimated based on the mathematical model denoting the relationship between the throughput, the wireless link quality information and the transmission rate, on the acquired transmission rate, and on the acquired wireless link quality information. [0180] (Supplementary Note 22) A throughput estimation computer program comprising instructions for causing an information processing device to carry out a process comprising the steps of: acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. [0181] (Supplementary Note 23) The throughput estimation computer program according to Supplementary Note 22, wherein it is configured to cause the information processing device to carry out the process of estimating the throughput based on a mathematical model denoting a relationship between the throughput and the wireless link quality information, and on the acquired wireless link quality information. [0182] (Supplementary Note 24) The throughput estimation computer program according to Supplementary Note 23, wherein the mathematical model is constructed by assuming equality between the throughput and a polynomial function with the wireless link quality information as a variable. [0183] (Supplementary Note 25) The throughput estimation computer program according to Supplementary Note 23, wherein it is configured to cause the information processing device to carry out the process further comprising the step of acquiring a transmission rate which is the amount of the data sent by the transmitting device to the mobile station per unit time, and estimating the throughput based on the mathematical model denoting the relationship between the throughput, the wireless link quality information and the transmission rate, on the acquired transmission rate, and on the acquired wireless link quality information. [0184] Further, the present application claims priority from Japanese Patent Application No. 2011-016232, filed on January 28, 2011 in Japan, the disclosure of which is incorporated herein by reference in its entirety. INDUSTRIAL APPLICABILITY [0185] The present invention is applicable to throughput estimation devices and the like to estimate throughput. REFERENCE SIGNS LIST [0186] 1 Mobile communication system 100 Transmitting device (Throughput estimation device) 101 Data transmission portion 102 Transmission rate acquisition portion 103 Reception rate acquisition portion 104 Wireless link quality information acquisition portion 105 Model parameter estimation portion 106 Throughput estimation portion 200 Receiving device (Mobile station) 201 Data reception portion 202 Received information transmission portion 203 Wireless link quality value acquisition portion 204 Wireless link quality value transmission portion 500 Throughput estimation device 501 Wireless link quality information acquisition portion 502 Throughput estimation portion BS Base station Ml Mobile body M2, M4 Springs M3, M5 Dashpots Wl First wall surface W2 Second wall surface CLAIMS 1. A throughput estimation device comprising: a wireless link quality information acquisition means for acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and a throughput estimation means for estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. 2. The throughput estimation device according to Claim 1, wherein the throughput estimation means is configured to estimate the throughput based on a mathematical model denoting a relationship between the throughput and the wireless link quality information, and on the acquired wireless link quality information. 3. The throughput estimation device ac cording to Claim 2, w herein t he mathematical model is constructed by assuming equality between the throughput and a polynomial function with the wireless link quality information as a variable. 4. The throughput estimation device ac cording to Claim 3, w herein t he mathematical model is constructed by assuming equality between the throughput and a linear function with the wireless link quality information as a variable. 5. The throughput estimation device according to Claim 2, further comprising a transmission rate acquisition means for acquiring a transmission rate which is the amount of the data sent by the transmitting device to the mobile station per unit time, wherein the throughput estimation means is configured to estimate the throughput based on the mathematical model denoting the relationship between the throughput, the wireless link quality information and the transmission rate, on the acquired transmission rate, and on the acquired wireless link quality information. 6. The throughput estimation device ac cording to Claim 5, wherein the mathematical model is expressed by an ordinary differential equation for the throughput with an inhomogeneous term of a function taking each of the transmission rate and the wireless link quality information as its variable. 7. The throughput estimation device according to Claim 6, wherein the inhomogeneous term is a product of the transmission rate and the polynomial function with the wireless link quality information as a variable. 8. The throughput estimation device according to Claim 7, wherein the inhomogeneous term is a product of the transmission rate and the linear function with the wireless link quality information as a variable. 9. The throughput estimation device according to any one of Claims 5 to 8, wherein the mathematical model is constructed by expressing the relationship between the throughput, the wireless link quality information and the transmission rate based on a dynamic model. 10. The throughput estimation device according to Claim 9, wherein the dynamic model comprises a mobile body movable in a preset moving direction; and at least one of an elastic body deforming in the moving direction as much as the displacement of the mobile body in the moving direction, and a viscous body delaying the movement of the mobile body in the moving direction. 11. The throughput estimation device according to Claim 10, wherein the mathematical model is constructed by assuming that an external force applied to the mobile body in the moving direction is as great as in accordance with the transmission rate and the wireless link quality information, and by assuming that the throughput is the distance in the moving direction between a preset reference position and the position of the mobile body. 12. The throughput estimation device according to Claim 11, wherein the mathematical model is constructed to let the inhomogeneous term express the external force. 13. The throughput estimation device according to any one of Claims 10 to 12, wherein the mathematical model is constructed by assuming that an elastic force generated by the elastic body is as great as the value of the displacement of the mobile body from a force-free position which is the position of the mobile body with the elastic force being zero, multiplied by an elastic coefficient which is a proportionality coefficient, and the elastic force acts in the opposite direction to the direction in which the mobile body has moved from the force-free position. 14. The throughput estimation device according to any one of Claims 10 to 13, wherein the mathematical model is constructed by assuming that a resisting force generated by the viscous body is as great as the velocity of the mobile body moving in the moving direction, multiplied by a viscosity coefficient which is another proportionality coefficient, and the resisting force acts in the opposite direction to the direction in which the mobile body moves. 15. The throughput estimation device according to any one of Claims 1 to 14, further comprising: a throughput acquisition means for acquiring the throughout, and a model parameter estimation means for estimating a model parameter for specifying the mathematical model, based on the acquired throughput and the acquired wireless link quality information. 16. The throughput estimation device according to any one of Claims 1 to 15, wherein the wireless link quality information is a value based on a channel quality indicator (CQI). 17. The throughput estimation device according to Claim 16, wherein the wireless link quality information is a value of having put the channel quality indicator through a smoothing process. 18. A throughput estimation method comprising: acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. 19. The throughput estimation method according to Claim 18, wherein the throughput is estimated based on a mathematical model denoting a relationship between the throughput and the wireless link quality information, and on the acquired wireless link quality information. 20. The throughput estimation method according to Claim 19, wherein the mathematical model is constructed by assuming equality between the throughput and a polynomial function with the wireless link quality information as a variable. 21. The throughput estimation method according to Claim 19, further comprising acquiring a transmission rate which is the amount of the data sent by the transmitting device to the mobile station per unit time, wherein the throughput is estimated based on the mathematical model denoting the relationship between the throughput, the wireless link quality information and the transmission rate, on the acquired transmission rate, and on the acquired wireless link quality information. 22. A throughput estimation computer program comprising instructions for causing an information processing device to carry out a process comprising the steps of: acquiring wireless link quality information denoting a quality of a wireless link established between a mobile station and a base station on a mobile communication network; and estimating a throughput which is the amount for the mobile station to receive per unit time a data sent by a transmitting device connected communicably with the mobile station via the wireless link, based on the acquired wireless link quality information. 23. The throughput estimation computer program according to Claim 22, wherein it is configured to cause the information processing device to carry out the process of estimating the throughput based on a mathematical model denoting a relationship between the throughput and the wireless link quality information, and on the acquired wireless link quality information. 24. The throughput estimation computer program according to Claim 23, wherein the mathematical model is constructed by assuming equality between the throughput and a polynomial function with the wireless link quality information as a variable. 25. The throughput estimation computer program according to Claim 23, wherein it is configured to cause the information processing device to carry out the process further comprising the step of acquiring a transmission rate which is the amount of the data sent by the transmitting device to the mobile station per unit time, and estimating the throughput based on the mathematical model denoting the relationship between the throughput, the wireless link quality information and the transmission rate, on the acquired transmission rate, and on the acquired wireless link quality information.