JP6816625B2 - Line design method and equipment - Google Patents

Description

The present invention relates to a method and an apparatus for performing line design.

For example, in order to realize multiple access in satellite communication, Demand Assigned Multiple Access (DAMA), which is a method of Frequency-Division Multiple Access (FDMA), is used. In FDMA, the communication frequency band is divided into a plurality of frequency bands (lines) and the lines are assigned to each radio station. In DAMA, by making a request to the line control station, the line is assigned to the radio station that made the request.
By the way, when carrying out satellite communication, it is necessary to determine the transmission power in advance for each assigned frequency so that the signal can be received while satisfying the specified C / No (carrier to noise ratio). Determining the transmission power in advance is called line design. In satellite communication, it is known that intermodulation occurs between the signals of the communication wave, and it is necessary to develop a line design method or a line design algorithm in consideration of the occurrence of intermodulation. Under conditions where intermodulation occurs, increasing the signal power of one communication wave increases the interference in other communication waves in that regard. The greater the interference in one of the communication waves, the greater the interference in the other communication wave. A chain of interference occurs in this way, but in some cases the chain of interference may circulate. When a circular chain of interference occurs, complicated calculations are required to achieve overall matching, and the calculation time becomes enormous. In some cases, the calculation may not be completed. The circular chain of interference due to intermodulation can occur not only in the case of satellite communication but also in the case of assigning different frequencies within the communication frequency band and setting a plurality of frequency arrangements.

As related to the line design in satellite communication, Patent Document 1 discloses a method capable of obtaining the number of lines that can be used at the same time in consideration of the influence of interference from other wireless lines. In Patent Document 2, a predetermined number of frequency bands (lines) are arranged in the communication frequency band to obtain the interference value in each line, and then the interference value in each line is obtained assuming that one of the lines does not exist. , It is disclosed that the allocation order when allocating a line by DAMA is determined from these results. Although these technologies are related to line design, it is not possible to perform line design that determines transmission power in advance using these technologies alone.

Japanese Unexamined Patent Publication No. 2011-119982 Japanese Unexamined Patent Publication No. 2014-239328

In line design, when a circular chain of interference due to intermodulation between lines occurs, complicated calculations are required to achieve overall matching, which increases the calculation time and in some cases the calculation may not be completed. ..
An object of the present invention is a line design method that can shorten the calculation time by eliminating the need for complicated calculation and surely complete the calculation when interference due to intermodulation can occur, and a line design device that executes this line design method. Is to provide.

In the line design method of the present invention, different frequencies are assigned within the communication frequency band to generate a plurality of frequency arrangements, and the relationship between the frequency arrangements that cause interference and the frequency arrangements that suffer interference in the plurality of frequency arrangements is used as a directed graph. Representing, judging whether or not there is a closed circuit in the directed graph, and if there is a closed circuit, delete one of the frequency arrangements to eliminate the closed circuit, and the directed graph in which the closed circuit is eliminated, each frequency arrangement is noded. It has the function of calculating the transmission power value for the frequency arrangement corresponding to each node while propagating the interference in the direction from the leaf to the root of the directed graph.
The line design device of the present invention performs mutual modulation between a frequency allocation generator that allocates different frequencies within a communication frequency band to generate a plurality of frequency allocations and a plurality of frequency allocations in which a frequency allocation generator occurs. The interference relationship determination unit that obtains the interference relationship, which is the relationship between the frequency arrangement that causes interference and the frequency arrangement that suffers interference, and expresses the interference relationship as a directed graph, determines whether or not there is a closed circuit in the directed graph, and the closed circuit is determined. If it exists, a closed circuit determination unit that deletes one of the multiple frequency arrangements generated by the frequency arrangement generating unit to eliminate the closed circuit, and a directed graph after the closed circuit is eliminated are used as nodes for each frequency arrangement. It has a transmission power calculation unit that calculates the transmission power value for the frequency arrangement corresponding to each node while propagating the interference in the direction from the leaf to the root in the tree structure.

According to the present invention, in the case where interference due to intermodulation can occur, complicated calculation is not required for line design, and the calculation of line design is surely completed.

It is a block diagram which shows the structure of the line design apparatus of 1st Embodiment. It is a flowchart which shows the operation of the line design apparatus shown in FIG. It is a block diagram which shows the structure of the line design apparatus of 2nd Embodiment. It is a flowchart which shows the operation of the line design apparatus shown in FIG. It is a figure which shows the example of the line design using the line design apparatus shown in FIG.

Next, an embodiment of the present invention will be described with reference to the drawings.
(First Embodiment)
FIG. 1 is a block diagram showing a configuration of a line design device according to the first embodiment. This line design device has the most basic configuration, and includes a frequency arrangement generation unit 21, an interference relationship determination unit 22, a cycle closing determination unit 23, and a transmission power calculation unit 24. The frequency arrangement generation unit 21 allocates different frequencies within the communication frequency band to generate a plurality of frequency arrangements. The interference relationship determining unit 22 obtains an interference relationship which is a relationship between a frequency arrangement that causes interference due to mutual modulation between frequency arrangements and a frequency arrangement that suffers from the interference in a plurality of frequency arrangements generated by the frequency arrangement generation unit 21. , This interference relationship is expressed as a directed graph. The cycle closing determination unit 23 determines whether or not there is a cycle (loop) in the directed graph showing the interference relationship, and if there is a cycle, any one of the plurality of frequency arrangements generated by the frequency arrangement generation unit 21. To eliminate the cycle. The transmission power calculation unit 24 treats the directed graph after the cycle is cleared as a tree structure having each frequency arrangement as a node, and propagates the interference in the direction from the leaves to the roots in the tree structure, and the frequency corresponding to each node. Calculate the transmit power value for the placement. Since the interference calculated by the transmission power calculation unit 24 is interference caused by mutual modulation, an algorithm for calculating the amount of interference and the transmission power value required in the presence of interference is widely known to those skilled in the art. It is a thing.

Next, the operation of the line design device shown in FIG. 1 will be described with reference to the flowchart of FIG. First, in step 101, the frequency arrangement generation unit 21 allocates different frequencies within the communication frequency band to generate a plurality of frequency arrangements. How the frequencies are assigned to each frequency arrangement in the communication frequency band can be arbitrary. For example, the frequencies of the communication frequency band may be randomly selected up to a predetermined number, and the selected frequencies may be made to correspond to the respective frequency arrangements. Alternatively, frequencies may be assigned to each frequency arrangement based on predetermined rules. The number of frequency arrangements to be generated can be input in advance to the frequency arrangement generation unit 21 as a control parameter, for example.

After the frequency arrangement is generated in step 101, then in step 102, the interference relationship determining unit 22 determines the relationship between the frequency arrangement that causes interference due to intermodulation between these frequency arrangements and the frequency arrangement that suffers from this interference. Express the interference relationship as a directed graph. Those skilled in the art are familiar with a method of obtaining the frequency at which interference occurs when the non-linearity of the system in which intermodulation occurs and the frequency arrangement are given, and the interference relationship determination unit 22 uses this well-known method. Based on this, the interference relationship is obtained and the interference relationship is expressed as a directed graph. At this time, in the directed graph, the interference relationship in the frequency arrangement can be expressed as an arrow (that is, a directed branch) from the frequency arrangement that gives interference to the frequency arrangement that suffers interference. As a matter of course, each frequency arrangement is treated as a node in the directed graph. The directed graph here is not limited to the one represented graphically by using arrows, but includes all the ones recognized as the representation of the directed graph in graph theory in mathematics. For example, it may be described based on a mapping between sets, for example, it may be represented by a relation expressed by a relational expression or a functional expression. Since interference caused by intermodulation is considered here, there are always two or more frequency arrangements that cause interference with respect to a certain frequency arrangement. That is, in the directed graph in the illustrated representation, for the node corresponding to the frequency arrangement suffering interference, there are two or more arrows pointing to the node. In most cases, it is not necessary to consider the interference from three different frequency arrangements, so it can be considered that there are two frequency arrangements that give the interference to one frequency arrangement that suffers the interference.

In the present embodiment, the directed graph shows the chain of interference in the interference relationship, and the cycle in the directed graph indicates that the chain of interference circulates. In order to eliminate the computational complexity of line design and to find the optimum value, it is necessary to eliminate the circular chain of interference. Therefore, in step 103, the cycle closing determination unit 23 determines whether or not a cycle (loop) exists in the directed graph showing the interference relationship. There are several known methods for determining a cycle in a directed graph, and among them, the method using topological sort is preferable in that the amount of calculation is small. If there is no cycle, the process proceeds to step 105. If there is a cycle, the cycle determination unit 23 eliminates the cycle by deleting any of the nodes constituting the cycle, that is, the frequency arrangement, in step 104, and then the process proceeds to step 105. Which frequency arrangement in the cycle to be deleted can be appropriately determined. Removing the frequency arrangement means that the frequency arrangement is not used and the transmission power is not defined.

According to the graph theory, a graph without a cycle has a tree structure, so the above-mentioned directed graph with the cycle deleted can also be treated as a tree structure. Therefore, in step 105, the transmission power calculation unit 24 treats the directed graph in which the cycle is eliminated as a tree structure having each frequency arrangement as a node, and responds to each node while propagating interference in the direction from the leaves to the roots in the tree structure. Calculate the transmission power value for the frequency arrangement to be performed. Here, the transmission power value is calculated from the leaf side of the tree structure, that is, the line design is performed because the node on the root side is affected by the line design result on the node on the leaf side. The line design is sequentially performed from the leaf side to the root side, and finally the line design is completed for all the nodes, that is, the frequency arrangements. As described above, in the present embodiment, since the order in which the line design is carried out can be determined by preventing the cyclic chain of interference, the complexity of the calculation can be eliminated, the calculation time can be shortened, and the calculation is completed. The sex can be guaranteed.

(Application example of the first embodiment)
In the first embodiment described above, the communication frequency band is, for example, a frequency band allocated for satellite communication, and a plurality of frequency arrangements are used within the communication frequency band when performing satellite communication by FDMA. The individual frequency channels that are used. When a plurality of frequency arrangements are generated in the communication frequency band, it is possible to generate as many frequency arrangements as the number of channels set for satellite communication in the communication frequency band. The present embodiment can also be used when designing a line for applications other than satellite communication.

(Second Embodiment)
In the first embodiment, since the frequency arrangement is deleted when the cycle closure in the directed graph is eliminated, the number of frequency arrangements in which the line design is performed may be smaller than the frequency arrangement initially generated. This will not meet the desire to provide a predetermined number of frequency channels in, for example, FDMA. Therefore, in this second embodiment, even when the frequency arrangement is deleted in order to eliminate the cycle closure in the directed graph, the number of frequency arrangements for which the line design is performed is not reduced. FIG. 3 shows the configuration of the line design device of the second embodiment.
The line design device shown in FIG. 3 further includes a frequency allocation addition unit 25 that adds the same number of frequency arrangements as the frequency arrangement deleted by the cycle closing determination unit 23 as a new frequency arrangement to the line design device shown in FIG. It is provided. In the present embodiment, the transmission power calculation unit 24 calculates the transmission power value including the new frequency arrangement added by the frequency arrangement addition unit 25.

Next, the operation of the line design device of this embodiment will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart showing the operation of the line design device shown in FIG. 3, and FIG. 5 is a diagram showing an example of line design in the present embodiment. Circled numbers in FIG. 5 indicate nodes corresponding to frequency arrangements.
First, steps 101 to 103 described in the first embodiment are executed. Here, in step 101, six frequency arrangements 1 to 6 within the communication frequency band (indicated by "[1]" to "[6]" in FIG. 5A, provided that the frequencies are different from each other. Frequency arrangement) is generated arbitrarily. In (A) of FIG. 5, the horizontal axis is frequency. When the interference relationship is expressed as a directed graph in step 102 ((B) in FIG. 5), for example, the directed graph shown in (C) of FIG. 5 is obtained. In this directed graph, a cycle of frequency arrangement 4 → frequency arrangement 2 → frequency arrangement 3 → frequency arrangement 4 occurs.

In step 103, the cycle closing determination unit 23 determines whether or not there is a cycle closure (loop) in the directed graph showing the interference relationship. However, in the present embodiment, if there is a cycle closure, the cycle closure determination unit 23 in step 106. 23 deletes any one frequency arrangement to eliminate the cycle corresponding to that frequency arrangement. Since there may be a plurality of cycles in the directed graph, step 103 is executed again after the execution of step 106, and it is determined whether or not there are further cycles. This process is shown by (D) to (F) in FIG. 5, and is repeated until all the closed cycles included in the directed graph are eliminated. For example, if a cycle exists in the directed graph as shown in FIG. 5 (C) and the frequency arrangement 1 is deleted for the purpose of eliminating the cycle, a directed graph as shown in FIG. 5 (E) is obtained. Be done. The directed graph of FIG. 5 (E) does not include a cycle.

If it is determined in step 103 that the closed circuit does not exist, the process proceeds to step 107 ((G) in FIG. 5). In step 107, the frequency allocation addition unit 25 newly adds the same number of frequency arrangements as the frequency arrangements deleted by the circuit closing determination unit 23 (frequency arrangements deleted in the processes (D) to (F) of FIG. 5). As a frequency arrangement, it is added to the frequency arrangement that was not deleted. The new frequency arrangement must not cause intermodulation interference with other frequency arrangements. The frequency of the new frequency arrangement that satisfies such a condition may be determined by trial and error, or the frequency that can cause interference with other frequency arrangements is calculated in advance and the frequency is calculated in the communication frequency band. You may decide to avoid such frequencies. In the example shown in FIG. 5, the frequency arrangement 1 has already been deleted, but as shown in FIG. 5 (H), the frequency arrangement 7 is added as a new frequency arrangement corresponding to the deletion of the frequency arrangement 1. ..

After the execution of step 107, similarly to step 105 in the first embodiment, in step 108 ((I) of FIG. 5), the transmission power calculation unit 24 includes the new frequency arrangement added in step 107. A directed graph is treated as a tree structure with each frequency arrangement as a node, and the transmission power value for the frequency arrangement corresponding to each node is calculated while propagating interference in the direction from the leaves to the roots in the tree structure. FIG. 5 (J) shows an example of a calculation in which interference is propagated from the leaves to the roots. As a result, as shown in FIG. 5 (K), the frequency arrangement in which the cyclic chain of interference is eliminated and the transmission power for each of those frequency arrangements are finally determined. FIG. 5 (L) shows an example of the frequency arrangement and the transmission power determined in this way, assuming that the horizontal axis is the frequency and the height of the hatched portion in a grid pattern indicates the transmission power. Here, the transmission power is calculated for the six frequency arrangements 2 to 7, and the line design for these frequency arrangements 2 to 7 is performed.

The line design device of each of the above-described embodiments can also be configured by a computer as an example. As the computer, a general personal computer or workstation can be used. When the line design device is configured by a computer, the computer may be loaded with a computer program for causing the computer to execute the process described with reference to FIG. 2 or 4, and the computer program may be executed. Therefore, the category of the present invention also includes such a computer program and a non-temporary recording medium in which the computer program is stored.

Some or all of the above embodiments may also be described, but are not limited to:

[Appendix 1] Assigning different frequencies within the communication frequency band to generate multiple frequency arrangements
To express the relationship between the frequency arrangement that causes interference due to intermodulation between frequency arrangements and the frequency arrangement that suffers from the interference in the plurality of frequency arrangements as a directed graph.
It is determined whether or not there is a cycle in the directed graph, and if the cycle exists, one of the frequency arrangements is deleted to eliminate the cycle.
The directed graph in which the cycle is eliminated is treated as a tree structure having each frequency arrangement as a node, and the transmission power value for the frequency arrangement corresponding to each node is calculated while propagating the interference in the direction from the leaves to the roots in the tree structure. To calculate and
A line design method that has.

[Appendix 2] The line design method according to Appendix 1, wherein the closing of the closed circuit is repeated until all the closed circuits included in the directed graph are cleared.

[Appendix 3] Add the same number of frequency arrangements as the frequency arrangements deleted in order to eliminate the closed circuit as new frequency arrangements, and calculate the transmission power value including the new frequency arrangements, in Appendix 1 or 2. The described line design method.

[Appendix 4] The line design method according to Appendix 3, wherein the new frequency arrangement is added while avoiding frequencies that may cause interference with other frequency arrangements.

[Supplementary Note 5] The line design method according to any one of Supplementary notes 1 to 4, wherein topological sort is applied to the directed graph to determine the presence or absence of the closed circuit.

[Appendix 6] The line design method according to any one of Appendix 1 to 5, wherein the plurality of frequency arrangements are frequency arrangements used in frequency division multiple access.

[Appendix 7] A frequency allocation generator that allocates different frequencies within the communication frequency band to generate a plurality of frequency allocations,
In a plurality of frequency arrangements in which the frequency arrangement generation unit is generated, the interference relationship, which is the relationship between the frequency arrangement that causes interference due to mutual modulation between frequency arrangements and the frequency arrangement that suffers from the interference, is obtained, and the interference relationship is used as a directed graph. Interference relationship determination part to express and
It is determined whether or not a cycle exists in the directed graph, and if the cycle exists, a cycle determination is determined in which one of the plurality of frequency arrangements generated by the frequency arrangement generating unit is deleted to eliminate the cycle. Department and
The directed graph after the cycle is cleared is treated as a tree structure having each frequency arrangement as a node, and transmission for the frequency arrangement corresponding to each node while propagating the interference in the direction from the leaf to the root in the tree structure. The transmission power calculation unit that calculates the power value and
Has a line design device.

[Appendix 8] The line design device according to Appendix 7, wherein the closed circuit determination unit repeats closing the closed circuit until all the closed circuits included in the directed graph are cleared.

[Appendix 9] Further having a frequency allocation addition unit for adding the same number of frequency arrangements as the frequency arrangement deleted by the cycle closing determination unit as a new frequency arrangement.
The line design device according to Appendix 7 or 8, wherein the transmission power calculation unit calculates the transmission power value including the new frequency arrangement added by the frequency arrangement addition unit.

[Appendix 10] The line design device according to Appendix 9, wherein the frequency arrangement addition unit adds the new frequency arrangement while avoiding frequencies that may cause interference with other frequency arrangements.

[Supplementary Note 11] The line design device according to any one of Supplementary note 7 to 10, wherein the closed circuit determination unit determines the presence or absence of the closed circuit by applying topological sort to the directed graph.

[Appendix 12] On the computer
Processing that allocates different frequencies within the communication frequency band to generate multiple frequency arrangements,
A process of treating the relationship between a frequency arrangement that causes interference due to intermodulation between frequency arrangements and a frequency arrangement that suffers from the interference as a directed graph in the plurality of frequency arrangements.
A process of determining the presence or absence of a cycle in the directed graph, and if the cycle exists, deleting one of the frequency arrangements to eliminate the cycle.
The directed graph in which the cycle is eliminated is treated as a tree structure having each frequency arrangement as a node, and the transmission power value for the frequency arrangement corresponding to each node is calculated while propagating the interference in the direction from the leaves to the roots in the tree structure. Processing to calculate and
A program that executes.

[Appendix 13] The program according to Appendix 12, wherein the computer is made to repeatedly execute the process of closing the cycle until all the cycles included in the directed graph are cleared.

[Appendix 14] To the computer
A process of adding the same number of frequency arrangements as the deleted frequency arrangement as a new frequency arrangement in order to eliminate the cycle is executed.
The program according to Appendix 12 or 13, which causes the transmission power value to be calculated including the new frequency arrangement in the calculation process.

[Appendix 15] The program according to Appendix 14, wherein in the process of adding, the computer is made to add the new frequency arrangement while avoiding frequencies that may cause interference with other frequency arrangements.

[Supplementary Note 16] The program according to any one of Supplementary note 12 to 15, wherein in the processing to be eliminated, the computer is made to apply topological sort to the directed graph to determine the presence or absence of the closed cycle.

21 Frequency allocation generator 22 Interference relationship determination unit 23 Cycle determination unit 24 Transmission power calculation unit 25 Frequency allocation addition unit 101-108 Steps

Claims (10)

Assigning different frequencies within the communication frequency band to generate multiple frequency arrangements,
To express the relationship between the frequency arrangement that causes interference due to intermodulation between frequency arrangements and the frequency arrangement that suffers from the interference in the plurality of frequency arrangements as a directed graph.
It is determined whether or not there is a cycle in the directed graph, and if the cycle exists, one of the frequency arrangements is deleted to eliminate the cycle.
The directed graph in which the cycle is eliminated is treated as a tree structure having each frequency arrangement as a node, and the transmission power value for the frequency arrangement corresponding to each node is calculated while propagating the interference in the direction from the leaves to the roots in the tree structure. To calculate and
A line design method that has. The line design method according to claim 1, wherein the closing of the closed circuit is repeated until all the closed circuits included in the directed graph are cleared. The line according to claim 1 or 2, wherein the same number of frequency arrangements as those deleted in order to eliminate the closed circuit are added as new frequency arrangements, and the transmission power value is calculated including the new frequency arrangements. Design method. The line design method according to claim 3, wherein the new frequency arrangement is added while avoiding frequencies that may cause interference with other frequency arrangements. The line design method according to any one of claims 1 to 4, wherein topological sort is applied to the directed graph to determine the presence or absence of the closed circuit. A frequency allocation generator that allocates different frequencies within the communication frequency band to generate multiple frequency allocations,
In a plurality of frequency arrangements in which the frequency arrangement generation unit is generated, the interference relationship, which is the relationship between the frequency arrangement that causes interference due to mutual modulation between frequency arrangements and the frequency arrangement that suffers from the interference, is obtained, and the interference relationship is used as a directed graph. Interference relationship determination part to express and
It is determined whether or not a cycle exists in the directed graph, and if the cycle exists, a cycle determination is determined in which any one of the plurality of frequency arrangements generated by the frequency arrangement generating unit is deleted to eliminate the cycle. Department and
The directed graph after the cycle is cleared is treated as a tree structure having each frequency arrangement as a node, and transmission for the frequency arrangement corresponding to each node while propagating the interference in the direction from the leaf to the root in the tree structure. The transmission power calculation unit that calculates the power value and
Has a line design device. The line design device according to claim 6, wherein the closed circuit determination unit repeats closing the closed circuit until all the closed circuits included in the directed graph are cleared. It further has a frequency allocation addition unit that adds the same number of frequency arrangements as the frequency arrangement deleted by the cycle closing determination unit as a new frequency arrangement.
The line design device according to claim 6 or 7, wherein the transmission power calculation unit calculates the transmission power value including the new frequency arrangement added by the frequency arrangement addition unit. The line design device according to claim 8, wherein the frequency arrangement adding unit adds the new frequency arrangement while avoiding frequencies that may cause interference with other frequency arrangements. On the computer
Processing that allocates different frequencies within the communication frequency band to generate multiple frequency arrangements,
A process of treating the relationship between a frequency arrangement that causes interference due to intermodulation between frequency arrangements and a frequency arrangement that suffers from the interference as a directed graph in the plurality of frequency arrangements.
A process of determining the presence or absence of a cycle in the directed graph, and if the cycle exists, deleting one of the frequency arrangements to eliminate the cycle.
The directed graph in which the cycle is eliminated is treated as a tree structure having each frequency arrangement as a node, and the transmission power value for the frequency arrangement corresponding to each node is calculated while propagating the interference in the direction from the leaves to the roots in the tree structure. Processing to calculate and
A program that executes.

Images