User Throughput Geographical Distribution Estimating System and User Throughput Geographical Distribution Estimating Method

The present invention relates to a user throughput geographical distribution estimation system and a user throughput geographical distribution estimation method, and in particular, estimates user throughput in a cellular system in which wireless packet communication is performed between a base station and a user terminal using a shared channel. Regarding the technology to do.

Conventionally, there is a cellular system including a user terminal and a base station that performs wireless packet communication between a user terminal in its own cell by using a shared channel.

In cellular systems, user throughput shows different values depending on the geography around the base station. The user throughput is a value measured by the user terminal and represents the number of bits of the packet received from the base station by the user terminal per unit time.

As a method of estimating the geographical distribution of user throughput in a cellular system, a method of continuously performing a system-level simulation of the cellular system by a computer is common. The reason is that the user terminals in the cell perform high-speed control and share the shared channel, so the sharing process is simulated continuously with high time resolution, and the wireless packet communication process including the upper layer is detailed. This is because the user throughput cannot be estimated accurately without simulation.

A conventional method for estimating the geographical distribution of user throughput will be described with reference to FIG.

As shown in FIG. 1, the continuous time system level simulation of the cellular system is performed by the system level simulator 300.

The system level simulator 300 uses the base station configuration, the amount of packet traffic generated when each user terminal requests download, and the total number of users in the cell as input values. The base station configuration represents the settings and status of the base station, for example, the position of the base station, transmission power, antenna pattern, antenna orientation, antenna tilt, and priority of packet transmission processing to the user terminal. The type of packet scheduler to be scheduled.

The system level simulator 300 estimates the reception quality of the shared channel at the position of each user terminal based on the above input values, and simulates a realistic wireless packet communication process for a continuous time including the upper layer of the protocol. , Estimate user throughput. As the reception quality of the shared channel, the reception SIR (Signal to Interference power Ratio), which represents the reception signal power to the interference wave signal power ratio of the shared channel, is usually used.

Here, the procedure of continuous time system level simulation by the system level simulator 300 will be described in detail.

The system level simulator 300 is HSDPA (High SPEED Downlink Packet Access), which is a high-speed downlink packet access of W-CDMA (Wide band-Code Division Multiple Access) as a downlink wireless packet communication method from a base station to a user terminal. When the method is used, the following first to fifth processes are simulated. First, the first process: users in various positions Raise the terminal. Then, after that, the user terminal is moved, and the user terminal makes a traffic request to the base station to transmit a packet on the shared channel. The traffic traffic of the packet requested here is the traffic traffic amount generated by the user terminal described above. -Second process: Estimate the reception quality of the shared channel at the position of each user terminal. Specifically, for each user terminal, the interference wave signal power of packets received from a plurality of base stations is calculated and repeated, and based on the calculation result, HS-PDSCH (High Speed-Physical Downlink Shared CHannel), which is a shared channel, is used. The reception quality of is calculated and estimated. -Third process: From the base station to each user terminal, the shared channel is assigned based on the amount of traffic generated by each user terminal, the reception quality of the shared channel at the position of each user terminal, and the packet scheduler of the base station. Use to send packets. -Fourth process: For each user terminal, the user throughput is calculated based on the number of bits of the packet received from the base station. When the fourth process is completed, the process returns to the first process. At this time, the position of each user terminal is updated according to the moving speed of the user terminal, and the first to fourth processes are repeated again. -Fifth process: Average the user throughput, which is the calculation result in the fourth process. Then, the position of the user terminal is output, and the average value of the user throughput of the user terminal is output as the estimation result of the user throughput.

The system level simulator 300 performs the first to fourth processes every 2 ms according to the real time. In addition, the system level simulator 300 In order to obtain statistically reliable user throughput estimation results, the first to fourth processes are simulated every 2 ms for over an hour.

As a result, the accuracy of the user throughput estimation result is improved. However, on the other hand, the amount of processing for simulating the first to fourth processes every 2 ms for one hour or more becomes extremely large, so that the estimated time for user throughput becomes long.

Further, since the system level simulator 300 performs the process of averaging the user throughput in the fifth process in order to display the geographical distribution of the user throughput, the estimated time of the user throughput becomes further longer.

Increasing the estimated time of user throughput becomes a problem especially when considering the appropriate value of the base station configuration according to the user throughput. When considering the proper value of the base station configuration, perform a system-level simulation every time the base station configuration is changed. Therefore, the system level simulation is repeated for a long time until the appropriate value of the base station configuration is determined, and the examination time becomes very long.

As other methods for estimating the conventional throughput, a method for estimating the throughput to determine the suitability for starting communication (see, for example, Japanese Patent Application Laid-Open No. 2000-224094) and a method for improving the system throughput (for example, special feature). There are methods for realizing a base station capable of estimating packet quality (see, for example, Japanese Patent Application Laid-Open No. 2004-112597).

Therefore, an object of the present invention is to provide a user throughput geographical distribution estimation system and a user throughput geographical distribution estimation method that can accurately and quickly estimate the geographical distribution of user throughput in a cellular system. ..

The user throughput geographic distribution estimation system of the present invention is a geography of user throughput in a cellular system including a user terminal and a base station that performs wireless packet communication between user terminals in its own cell using a shared channel. It is applied to estimate the target distribution.

The user throughput geographical distribution estimation system of the present invention provides a reception quality estimation means for estimating the reception quality of the shared channel at the position of the user terminal in the cell, and traffic information in the estimation target range in which the reception quality is estimated. Using the user throughput calculation function that calculates the user throughput using the traffic information reading means to be read, the reception quality of the shared channel at the position of the user terminal in the cell, and the traffic information in the estimation target range as input values, in the cell. The configuration includes a user throughput estimation means for estimating the user throughput at the position of the user terminal.

Since the output value corresponding to the input value is fixed in a function such as the user throughput calculation function, it is possible to obtain the output value instantly when the input value is obtained. Therefore, according to the configuration using the function as described above, the process in which the user terminal shares the shared channel by the processing of the packet scheduler is performed in detail with high time resolution continuously time as compared with the configuration using the conventional system level simulation. Since there is no need to simulate, the geographical distribution of user throughput can be estimated in a short time.

Further, the traffic information reading means may be configured to read the traffic information in the estimation target range measured by either the base station or the wireless network control device. According to this configuration, the input value of the user throughput calculation function can be set to a value close to reality, so that the estimation accuracy of the user throughput can be improved.

Further, the user terminal measuring means for traveling in the cell and measuring the reception quality and the user throughput of the shared channel at the position of the user terminal in the cell is further provided, and the user throughput estimating means is the reception quality of the shared channel. The configuration may include a function correction means for correcting the user throughput calculation function according to the relationship between the actually measured value and the actually measured value of the user throughput. According to this configuration, the user throughput calculation function corrected according to the relationship between the measured value of the reception quality of the shared channel and the measured value of the user throughput can be used, so that the estimation accuracy of the user throughput can be improved. Can be done.

<figref num="1">It is a figure explaining the conventional user throughput geographical distribution estimation method.</figref><figref num="2">It is a block diagram which shows the structure of the user throughput geographical distribution estimation system by Example 1 of this invention.</figref><figref num="3">It is a graph explaining the example of the user throughput calculation function used in Example 1 of this invention.</figref><figref num="4">It is a figure which shows the display example of the geographical distribution of the user throughput using the estimation result of the user throughput estimated in Example 1 of this invention.</figref><figref num="5">It is a block diagram which shows the structure of the user throughput geographical distribution estimation system by Example 2 of this invention.</figref><figref num="6">It is a block diagram which shows the structure of the user throughput geographical distribution estimation system by Example 3 of this invention.</figref><figref num="7">It is a graph explaining the example of the user throughput calculation function used in Example 3 of this invention.</figref><figref num="8">It is a block diagram which shows the structure of the user throughput geographical distribution estimation system by Example 4 of this invention.</figref><figref num="9">It is a graph explaining the example of the user throughput calculation function used in Example 4 of this invention.</figref><figref num="10">It is a block diagram which shows the structure of the user throughput geographical distribution estimation system by 8th Example of this invention.</figref><figref num="11">It is a graph explaining an example of the method of correcting a user throughput calculation function by the function of the user terminal actual measurement value.</figref>

Hereinafter, examples of the user throughput geographical distribution estimation system of the present invention will be described with reference to the drawings. In the following description, it is assumed that the W-CDMA HSDPA method is used as the downlink wireless packet communication method from the base station to the user terminal.

FIG. 2 is a block diagram showing the configuration of the user throughput geographical distribution estimation system according to the first embodiment of the present invention. The cellular system to which this embodiment is applied is a cellular system including a user terminal and a base station that performs wireless packet communication between a user terminal and a user terminal in its own cell by using a shared channel. To do.

Referring to FIG. 2, the user throughput geographical distribution estimation system according to the present embodiment includes a reception quality estimation means 11, a traffic information reading means 12, and a user throughput estimation means 13.

The reception quality estimation means 11 assumes that the user terminals exist at various positions in the cell. Then, the reception quality estimation means 11 has a propagation loss between the base station and each user terminal based on the position of the base station input as the base station configuration and the position of each user terminal in the cell. To calculate. The propagation loss is derived by substituting the distance between the base station and each user terminal into a predetermined propagation equation.

Further, the reception quality estimation means 11 in the cell is based on the packet transmission power, the antenna pattern, and the antenna direction on the shared channel, which are input as the base station configuration, and the calculation result of the propagation loss calculated above. Estimate the reception quality of the shared channel at the position of each user terminal. As the reception quality, the reception SIR shall be used.

The reception quality estimating means 11 outputs the position of each user terminal in the cell and the reception quality of the shared channel at that position. Of these, the reception quality of the shared channel is output to the user throughput estimation means 13.

The traffic information reading means 12 reads the traffic information in the estimation target range in which the reception quality is estimated by the reception quality estimating means 11 from the outside, and outputs the read traffic information to the user throughput estimating means 13. The traffic information in the estimation target range is the load applied to the estimation target range by the packet generated by the user terminal existing in the estimation target range.

For example, the transmission power of a base station is generally used as an index of downlink traffic information of W-CDMA. On the downlink, as the number of user terminals in the cell increases, the total transmission power used by the base station to transmit packets to the user terminals in the cell increases. That is, the traffic information is a quantitative value related to the number of user terminals in the cell.

Therefore, in the first to fourth embodiments of the present invention, the traffic information in the estimation target range will be defined as the number of user terminals in the cell. However, it is assumed that this traffic information is a value larger than "0".

The user throughput estimation means 13 has a built-in user throughput calculation function f that calculates the user throughput U by using the reception quality of the shared channel and the traffic information in the estimation target range as input values.

The user throughput estimation means 13 receives the above-mentioned user throughput calculation function with respect to the input of the reception quality of the shared channel output from the reception quality estimation means 11 and the traffic information in the estimation target range output from the traffic information reading means 12. Using f, the user throughput at the position of each user terminal in the cell is calculated and output as the estimation result of the user throughput.

The user throughput calculation function f is prepared in advance using the estimation result of the user throughput by the system level simulation, the measured value of the user throughput received from the wireless network controller, the result of the approximate analysis of the user throughput, and the like, and the user throughput is prepared in advance. It is built into the estimation means 13.

If the user throughput calculation function f is approximated and formulated as a continuous function whose input values are the reception quality of the shared channel and the traffic information in the estimation target range, the estimation process when there are continuous input values becomes easy. ..

As a qualitative property of user throughput, if the reception quality of the shared channel is high, the user throughput increases, and if there is a lot of traffic, the user throughput decreases. From this, the following equation 1 can be used as an example of the user throughput calculation function f.

<maths num="1"><img file="JP4636282B2_D0001.tif" /></maths> In Equation 1, U is user throughput, SIR is shared channel reception quality, and Load_cellIs traffic information in the estimated target range (= number of user terminals in the cell. However, Load_cell&gt; 0), A is an arbitrary constant used for exponentiation, B is an arbitrary constant used for exponentiation, and C is an arbitrary constant.

As described above, the higher the reception quality of the shared channel, the higher the user throughput. Therefore, Equation 1 takes the form of the numerator of the value obtained by raising the reception quality of the shared channel. In addition, if the traffic increases, the user throughput decreases. Therefore, Equation 1 takes the form of the denominator being the power of the traffic information. The arbitrary constants A, B, and C need to be adjusted in advance in order to approximate the user throughput calculation function f to the estimation result of the system level simulation.

FIG. 3 is a graph illustrating an example of the user throughput calculation function f used in the first embodiment of the present invention.

The user throughput calculation function f can be represented by a graph as shown in FIG. 3 when the horizontal axis is the reception quality of the shared channel and the vertical axis is the user throughput, and the traffic information in the estimation target range is used as a parameter.

In this embodiment, the user throughput is estimated at the position of each user terminal in the cell assumed by the reception quality estimating means 11 and the position of each user terminal in the cell estimated by the user throughput estimating means 13. The result is also output. Therefore, it is possible to estimate the geographical distribution of user throughput within the cell based on these outputs.

FIG. 4 is a diagram showing a display example of the geographical distribution of user throughput using the estimation result of user throughput estimated in Example 1 of the present invention.

Reference to FIG. 4 shows the geographical distribution of user throughput of user terminals around a three-sector base station. As shown in FIG. 4, the geographical distribution of user throughput should be displayed in a plane so that it can be easily grasped visually, and it is better to display it in different colors.

As described above, in the present embodiment, the user throughput estimation means 13 inputs the reception quality of the shared channel at the position of each user terminal in the cell and the traffic information in the estimation target range into the user throughput calculation function f. Therefore, the user throughput at the position of each user terminal in the cell is calculated.

Since the output value corresponding to the input value is fixed in a function such as the user throughput calculation function f, it is possible to obtain the output value instantly when the input value is obtained. Therefore, the estimation method using such a function does not need to simulate the process of wireless packet communication in detail for continuous time as compared with the estimation method using the conventional system level simulation, so that the geographical distribution of user throughput can be shortened in a short time. Can be estimated with.

By the way, as described above, the user throughput calculation function f estimates the user throughput only with two pieces of information, that is, the reception quality of the shared channel at the position of each user terminal in the cell and the traffic information in the estimation target range. Is possible. The rationale for estimating user throughput with only two pieces of information is as follows.

The user throughput is basically determined according to the frequency with which the radio resource is allocated to the user terminal and the transmission rate of the radio link when the radio resource is allocated. The frequency with which radio resources are allocated to user terminals is related to the degree of congestion of user terminals at the base station, that is, traffic in the estimation target range. Also, the transmission rate of the radio link is related to the reception quality of the shared channel of the radio link. Further, in terms of user throughput, qualitatively, if the degree of congestion of the user terminal in the base station is high, the user throughput tends to decrease, and if the degree of congestion of the user terminal is low, the user throughput tends to increase.

Also, in HSDPA, if the reception quality of the shared channel is high, a modulation method with a high transmission rate is selected, so the transmission rate rises, and if the reception quality of the shared channel is low, a modulation method with a low transmission rate is selected. , The transmission rate tends to decrease.

Even in wireless packet communication methods other than HSDPA, if the reception quality of the shared channel is high, the error rate is low, so the effective transmission rate increases, and if the reception quality of the shared channel is low, the error rate is high, so the effective transmission rate decreases. .. Therefore, there is a tendency similar to the above-mentioned HSDPA.

From the above, the correspondence between the reception quality of the shared channel, the traffic information in the estimation target range, and the user throughput is qualitatively determined. Therefore, the correspondence is acquired in advance by using the estimation result of the user throughput by the system level simulation, the measured value of the user throughput received from the wireless network control device, the result of the approximate analysis of the user throughput, and the like. Approximate and formulate. As a result, it is possible to estimate the user throughput with only two pieces of information, the reception quality of the shared channel and the traffic information in the estimation target range.

In this way, the method of estimating the user throughput based on only two pieces of information, the reception quality of the shared channel and the traffic information in the estimation target range, is very simple because the factors that affect the user throughput are extremely limited. It can be said that it is a modified method.

However, with the simplification of the estimation method, some deterioration occurs in the estimation accuracy. However, by accurately formulating the user throughput calculation function f in order to approximate the result of system level simulation, the estimation time can be significantly shortened with good estimation accuracy that does not cause any practical problems. You can get the benefits.

In particular, when examining the appropriate value of the base station configuration, it is important to change the base station configuration several times to quickly obtain the appropriate value. Therefore, the high-speed estimation method of the user throughput according to this embodiment can significantly shorten the examination time for the appropriate value of the base station configuration.

FIG. 5 is a block diagram showing the configuration of the user throughput geographical distribution estimation system according to the second embodiment of the present invention.

Referring to FIG. 5, the user throughput geographic distribution estimation system according to this embodiment is applied to a different cellular system as compared with Example 1 shown in FIG. That is, the wireless network control device 100 is added to the cellular system to which this embodiment is applied. The other configurations of this embodiment are the same as those of the first embodiment shown in FIG. 2, and the same components are designated by the same reference numerals.

In FIG. 5, base stations 101 to 103 are connected to the wireless network control device 100. In addition, three user terminals 1031 to 1033 exist in the cell of the base station 103.

In this embodiment, the base stations 101 to 103 or the wireless network control device 100 measure the number of user terminals in the cell, and the measured number of user terminals is used as the traffic information in the estimation target range by the traffic information reading means 12. Output.

For example, when estimating the user throughput in the cell of the base station 103, the base station 103 or the wireless network controller 100 measures the number of user terminals in the cell of the base station 103, and the measured number of user terminals is calculated. It is output to the traffic information reading means 12 as the traffic information in the estimation target range. Note that FIG. 5 shows an example in which the wireless network control device 100 measures the number of user terminals in the cell 103.

Similarly, when estimating the user throughput in the cells of the base stations 101 and 102, the corresponding base station or the wireless network controller 100 measures the number of user terminals in the cell of the corresponding base station, and the measured user terminals. Is output to the traffic information reading means 12 as the traffic information in the estimation target range.

Traffic information changes from moment to moment. Therefore, the traffic information reading means 12 may read the traffic information in real time and output it to the user throughput estimation means 13, or the maximum value of the traffic information read in a certain period (for example, one day) is estimated by the user system throughput. It may be output to means 13.

As described above, in the present embodiment, since the traffic information reading means 12 is configured to output the traffic information actually measured by the cellular system, the user throughput estimating means 13 uses accurate traffic information for estimating the user throughput. be able to. As a result, it is possible to improve the estimation accuracy of the user throughput.

For example, when the traffic information reading means 12 is configured to output the measured value of the traffic information in the estimation target range in real time, the user throughput estimating means 13 can estimate the user throughput in real time. As a result, it is possible to discover in real time the points where the user throughput has decreased in the cell.

Alternatively, if the maximum value of the traffic information in the estimation target range read by the traffic information reading means 12 in a certain period (for example, one day) is output to the user system throughput estimating means 13, the appropriate value of the base station configuration is used. As a result, it is possible to consider an appropriate value that can withstand the maximum traffic information during a certain period.

FIG. 6 is a block diagram showing the configuration of the user throughput geographical distribution estimation system according to the third embodiment of the present invention.

The user throughput geographical distribution estimation system according to the present embodiment with reference to FIG. 6 is different from the second embodiment shown in FIG. 5 in that the packet scheduler reading means 14a is added. The other configurations of this embodiment are the same as those of the second embodiment shown in FIG. 5, and the same components are designated by the same reference numerals.

The packet scheduler reading means 14a reads the type of packet scheduler used in the base station (which schedules the priority of packet transmission processing to the user terminal using the shared channel), and determines the type of the read packet scheduler. Output to user throughput estimation means 13.

The user throughput estimation means 13 has a built-in user throughput calculation function f1 in which the type of packet scheduler is added as a new parameter to the user throughput calculation function f used in the above-described first embodiment.

The user throughput estimation means 13 includes the reception quality of the shared channel output from the reception quality estimation means 11, the traffic information in the estimation target range output from the traffic information reading means 12, and the packet output from the packet scheduler reading means 14a. In response to the input of the scheduler type, the user throughput calculation function f1 is used to calculate the user throughput at the position of each user terminal in the cell, and output as the estimation result of the user throughput.

The user throughput calculation function f1 may be prepared for each type of packet scheduler, or may be approximated and formulated as a continuous function as in the above-described first embodiment. When the user throughput calculation function f1 is approximated as a continuous function and formulated, the following formula 2 can be used as an example of the user throughput calculation function f1.

<maths num="2"><img file="JP4636282B2_D0002.tif" /></maths> In Equation 2, U is user throughput, SIR is shared channel reception quality, Scheduler is packet scheduler type, and Load_cellIs the traffic information in the estimation target range (= number of user terminals in the cell. However, Load_cell&gt; 0), D (Schedular) is a constant determined by the type of packet scheduler, E is an arbitrary constant, and G is an arbitrary constant used for power.

User throughput increases or decreases depending on the type of packet scheduler. Therefore, Equation 2 takes the form of multiplying the constant D according to the type of packet scheduler by the user throughput calculation function f used in Example 1 described above. Also, the effect of the packet scheduler tends to decrease as the traffic increases. Therefore, Equation 2 takes the form of dividing the constant D by the traffic information.

FIG. 7 is a graph illustrating an example of the user throughput calculation function f1 used in the third embodiment of the present invention.

The user throughput calculation function f1 can be represented by a graph in which the horizontal axis is the reception quality of the shared channel and the vertical axis is the user throughput, and the types of the packet scheduler and the traffic information in the estimation target range are used as parameters. For example, when the traffic information in the estimation target range is fixed and the type of packet scheduler is changed, the user throughput calculation function f1 can be represented by a graph as shown in FIG. 7.

As described above, in the present embodiment, the user throughput estimation means 13 is configured to calculate the user throughput by adding the type of the packet scheduler output from the packet scheduler reading means 14a as a new parameter, which is more realistic. User throughput close to can be estimated. As a result, the estimation accuracy of user throughput can be further improved.

FIG. 8 is a block diagram showing the configuration of the user throughput geographical distribution estimation system according to the fourth embodiment of the present invention.

Referring to FIG. 8, the user throughput geographical distribution estimation system according to the present embodiment is different from the third embodiment shown in FIG. 6 in that the shared channel usage ratio reading means 14b is added. The other configurations of this embodiment are the same as those of the third embodiment shown in FIG. 6, and the same components are designated by the same reference numerals.

The shared channel usage ratio reading means 14b is used only for all user terminals in the cell (user terminals that perform wireless packet communication using the shared channel and individual channels individually assigned by the base station without using the shared channel). The ratio of the user terminal that performs wireless packet communication using the shared channel is read for the user terminal that performs voice communication or the like using the above, and the read ratio is output to the user throughput estimation means 13. The ratio of user terminals using the shared channel may be estimated by the shared channel usage ratio reading means 14b based on the penetration rate of the user terminals using the shared channel, or may be obtained by the wireless network control device 100. If it is possible to measure with, the result actually measured by the wireless network control device 100 may be used by the shared channel usage ratio reading means 14b.

The user throughput estimation means 13 has a built-in user throughput calculation function f2 in which the ratio of user terminals using the shared channel is added as a new parameter to the user throughput calculation function f1 used in Example 3 described above. ing.

The user throughput estimation means 13 includes the reception quality of the shared channel output from the reception quality estimation means 11, the traffic information in the estimation target range output from the traffic information reading means 12, and the packet output from the packet scheduler reading means 14a. The user throughput calculation function f2 is used to input the type of scheduler and the ratio of user terminals that use the shared channel output from the shared channel usage ratio reading means 14b at the position of each user terminal in the cell. The user throughput is calculated and output as the estimation result of the user throughput.

A user terminal that uses only an individual channel has a greater influence on traffic than a user terminal that uses a shared channel. For example, a user terminal that uses a shared channel uses wireless resources (power and frequency of a base station) only when necessary, so that the frequency of use of wireless resources is low. On the other hand, a user terminal that uses only individual channels continuously consumes the radio resources of the individually assigned individual channels during communication, and it takes time for connection processing, so that the radio resources are frequently used.

That is, a user terminal that uses only individual channels has a greater influence of increasing traffic than a user terminal that uses a shared channel, which causes a decrease in user throughput U.

Considering this, when the user throughput calculation function f2 is approximated and formulated as a continuous function as in the first embodiment, the following equation 3 can be used as an example of the user throughput calculation function f2.

<maths num="3"><img file="JP4636282B2_D0003.tif" /></maths> In Equation 3, U is user throughput, SIR is shared channel reception quality, and Load_cellIs the traffic information in the estimation target range (= number of user terminals in the cell. However, Load_cell&gt; 0), Scheduler is the type of packet scheduler, Ratio_SCHIs the ratio of user terminals that use shared channels, D (Schedular) is a constant determined by the type of packet scheduler, G is an arbitrary constant used for exponentiation, and H is the effect of user terminals that use only individual channels on traffic. The coefficient representing, J is an arbitrary constant.

Equation 3 is basically the same as Equation 2 used in Example 3 described above, but the traffic in the estimation target range is approximated to the traffic considering the degree of influence of the user terminal using only the individual channel. I'm taking.

In the denominator of Equation 3, (1-Ratio_SCH) Represents the percentage of user terminals that use only individual channels. The result of multiplying this ratio by the coefficient H represents the ratio of effective user terminals that use only individual channels and affect traffic. Ratio of user terminals that use the shared channel to this ratio_SCHAfter adding, traffic information Load_cellThe result of multiplying by is the result of approximating the traffic in the estimation target range, and [{Ratio_SCH+ H × (1-Ratio_SCH)} × Load_cell] Is represented.

FIG. 9 is a graph illustrating an example of the user throughput calculation function f2 used in the fourth embodiment of the present invention.

The user throughput calculation function f2 has the reception quality of the shared channel on the horizontal axis and the user throughput on the vertical axis, and the parameters are the ratio of user terminals using the shared channel, the type of packet scheduler, and the traffic information in the estimation target range. It can be represented by a graph. For example, when the type of packet scheduler and the traffic information in the estimation target range are fixed and the ratio of user terminals using the shared channel is changed, the user throughput calculation function f2 can be represented by a graph as shown in FIG. it can.

As described above, in the present embodiment, the user throughput estimation means 13 calculates the user throughput by adding the ratio of the user terminals using the shared channel output from the shared channel usage ratio reading means 14b as a new parameter. Because of this configuration, it is possible to estimate user throughput that is closer to reality. As a result, the estimation accuracy of user throughput can be further improved.

In future cellular systems, it is expected that the proportion of user terminals that use shared channels will gradually increase with the spread of HSDPA-compatible user terminals. In the process of maturation and development of the cellular system in this way, it is considered that the above-mentioned method for estimating user throughput is particularly effectively used.

The user throughput geographical distribution estimation system according to the fifth embodiment of the present invention is different from the first to fourth embodiments only in that the traffic information in the estimation target range is defined as the system throughput.

The user throughput is the throughput measured from the viewpoint of the user terminal, that is, the throughput measured on the user terminal side. On the other hand, the system throughput is the throughput measured from the viewpoint of the base station side of the system, that is, the throughput measured on the base station side. The system throughput represents the total number of bits of all packets transmitted by the base station to all user terminals in the cell per unit time.

As described in Example 1, the traffic information in the estimation target range is a quantitative value related to the number of user terminals in the cell. Here, since the frequency, time, and power of one cell are finite, naturally, the amount of communication that one cell can handle is finite. Considering this, the traffic information in the estimation target range can be grasped as the degree of congestion of the user terminal in the cell.

Therefore, in this embodiment, the system throughput of the base station, which tends to be proportional to the number of user terminals, is used as traffic information in the estimation target range.

The user throughput geographical distribution estimation system according to the sixth embodiment of the present invention defines the traffic information in the estimation target range as the average number of simultaneous connections of user terminals in the cell as compared with the first to fifth embodiments. Is different.

The average number of simultaneous connection of user terminals in a cell is the average number of user terminals connected to the base station at the same time in the cell over a certain period of time. This value is measurable at the base station and clearly tends to be proportional to the number of user terminals in the cell.

Therefore, in this embodiment, the average number of simultaneous connections of user terminals in the cell, which tends to be proportional to the number of user terminals, is used as traffic information in the estimation target range.

The user throughput geographic distribution estimation system according to Example 6 of the present invention defines the traffic information in the estimation target range as the usage time rate of the packet transmission power of the base station in the cell as compared with Examples 1 to 6. The only difference is that they are.

The usage time rate of the packet transmission power of the base station in the cell is the temporal usage rate of the packet transmission power used by the base station to transmit the packet to the user terminal in the cell.

If the user terminal does not exist in the cell, the base station does not transmit the packet, so that the temporal usage rate of the packet transmission power of the base station decreases. On the contrary, if there are many user terminals in the cell, the temporal usage rate of the packet transmission power of the base station increases. That is, this value is measurable at the base station and clearly tends to be proportional to the number of user terminals in the cell.

Therefore, in this embodiment, the usage time rate of the transmission power of the base station in the cell, which tends to be proportional to the number of user terminals, is used as the traffic information in the estimation target range.

FIG. 10 is a block diagram showing a configuration of a user throughput geographical distribution estimation system according to an eighth embodiment of the present invention.

Referring to FIG. 10, the user throughput geographical distribution estimation system according to the eighth embodiment of the present invention has the user terminal actual measurement means 200 and the user terminal actual measurement value reading means 15 as compared with the fourth embodiment shown in FIG. The difference is that the function correction means 13a provided inside the user throughput estimation means 13 is added. The other configurations of this embodiment are the same as those of the fourth embodiment shown in FIG. 8, and the same components are designated by the same reference numerals.

For example, when estimating the user throughput in the cell of the base station 103, the user terminal actual measurement means 200 travels in the cell of the base station 103 and receives a shared channel at each position of the user terminals 1031 to 1033 in the cell. Measure quality and user throughput at the same time.

The user terminal actual measurement value reading means 15 reads the actual measurement value of the reception quality of the shared channel measured by the user terminal actual measurement means 200 and the actual measurement value of the user throughput. Then, the user terminal actual measurement value reading means 15 creates a function fc that represents the relationship between the actual measurement value of the reception quality of the shared channel and the actual measurement value of the user throughput after averaging the read actual measurement values over a certain period of time. To do. The reason for averaging is that since the fluctuation range of the user throughput with respect to the reception quality of the shared channel is large, it is effective to use the average value of the user throughput with respect to the reception quality. Further, the user terminal actual measurement value reading means 15 outputs the function fc of the actual measurement value to the function correction means 13a in the user throughput estimation means 13.

The function correction means 13a corrects the user throughput calculation function f2 based on the function fc of the measured value output from the user terminal actual measurement value reading means 15. Specifically, as shown in FIG. 11, the function correction means 13a corrects the actually measured value function fc and the function f2 before correction into a function f2'that is averaged. As the above-mentioned specific correction method, the function correction means 13a can use the following mathematical formula 4.

<maths num="4"><img file="JP4636282B2_D0004.tif" /></maths> In Equation 4, f2'is the corrected user throughput calculation function, f2 is the uncorrected user throughput calculation function, and fc is the function of the measured value of the user terminal.

As another correction method, the function correction means 13a applies a weighted average to both the function fc of the measured value and the function f2 before the correction in consideration of the amount of data of the measured value and the reliability of the measured value. You can take the method.

The user throughput estimation means 13 estimates the user throughput using the user throughput calculation function f2 corrected by the function correction means 13a, using the same parameters as in the fourth embodiment as input values.

As described above, in this embodiment, the user throughput estimation means 13 uses the function f2'in which the user throughput function f2 is corrected according to the measured value of the reception quality of the shared channel and the measured value of the user throughput. Because of the configuration that calculates, it is possible to estimate the user throughput that is closer to reality. As a result, the estimation accuracy of user throughput can be further improved.

As described above, in the present invention, the user throughput is estimated by inputting the reception quality of the shared channel at the position of the user terminal and the traffic information in the estimation target range into the user throughput calculation function.

Since the output value corresponding to the input value is fixed in a function such as the user throughput calculation function, it is possible to obtain the output value instantly when the input value is obtained. Therefore, the estimation method using such a function requires detailed continuous time simulation of the process in which the user terminal shares a shared channel by the processing of the packet scheduler with high time resolution, as compared with the estimation method using the conventional system level simulation. Therefore, the geographical distribution of user throughput can be estimated in a short time.

Further, in the present invention, since the estimation result of the system level simulation or the like is reflected as the user throughput calculation function, the estimation accuracy of the user throughput can be improved.

Further, in the present invention, the measured value may be used as the traffic information in the estimation target range which is the parameter of the user throughput calculation function. That is, in the present invention, since the input value of the user throughput calculation function can be set to a value close to reality, it is possible to improve the estimation accuracy of the user throughput.

Furthermore, in the present invention, the user throughput calculation function can be corrected according to the relationship between the measured value of the reception quality of the shared channel at the position of the user terminal and the measured value of the user throughput. Therefore, the present invention can use a user throughput calculation function according to the relationship between the reception quality of the shared channel and the user throughput, which is close to reality, so that the user throughput can be estimated accurately.