JP2762727B2 - Satellite line demand allocation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a satellite channel demand allocating device used in a satellite communication earth station.

(Prior Art) A satellite line demand allocating device is a control device for allocating and using a satellite line each time in response to a demand request, instead of constantly setting and using a satellite line between earth stations. is there. Therefore, more earth stations and terminals than the number of satellite lines can share and use the satellite line.
Hereinafter, an earth station that performs all the management related to the assignment of satellite links is called a hub station, and a plurality of earth stations that issue a satellite link assignment request to the hub station are called remote stations. SCPC / FDMA
FIG. 11 shows an example of a configuration of a conventional satellite channel demand allocating apparatus on the hub station side. The conventional satellite channel demand assignment device on the hub station side shown in FIG. 1 includes a signaling processing unit 11, a call processing unit 12, a satellite channel management unit 13, and a device control unit 14. The signaling processing unit 11 receives and processes a demand assignment request from a remote station, a terminal connected to the earth station, or the like. The call processing unit 12 manages various states of the call, and performs processing according to the state of the call, such as calling processing and disconnection processing. The satellite line management unit 13 manages the state of use of the satellite line and allocates an appropriate line in response to a demand assignment request. The device control unit 14 receives the instruction from the call processing unit 12 and
Frequency setting and carrier on / off. Which modulator / demodulator 15 is used for communication at which frequency is set for each demand allocation request.

Next, FIG. 12 shows an example of a configuration of a remote station side of a conventional satellite channel demand assignment device. The conventional satellite line demand assignment device on the remote station side shown in FIG.
1, a call processing unit 12, and a device control unit 14. Each part of the device performs basically the same function as the corresponding device of the hub station equipment. The difference from the hub station equipment is that the satellite line management unit 13 is not provided. When a demand assignment request occurs, all satellite channels to be used (such as the frequency setting of the modem 15) are determined subordinately based on assignment instructions from the hub station.

(Problems to be Solved by the Invention) However, the problem in the above-described conventional device occurs when the conventional satellite channel demand assignment device is used for an earth station used in a situation where there are many unnecessary interference waves. Many of the frequencies used in satellite communications are shared with other systems such as terrestrial microwave systems. In an earth station that needs to receive a weak radio wave from a satellite, radio wave interference from another system becomes a problem. Especially in a place where there is a lot of radio wave interference such as in a city, communication may not be possible due to the interference. The state of radio interference varies depending on the location of the earth station as well as over time.

In the conventional satellite channel demand allocation device, the satellite channel manager 13 of the hub station holds usable satellite channel frequencies and allocation status (hereinafter, a channel allocation status table 16). For example, if all the lines to be used are of the same type (carrier parameter: transmission rate, modulation method, etc.), the line management unit manages a table as shown in FIG. In the figure, the line with line number 1 is connected to the earth station # 13 and the line # N-1
This indicates that the # 7 line is allocated to the earth station and the other lines are open. Since such line management is performed, the following problems occur when used in a network including an earth station (a hub station and a plurality of remote stations) used in a situation where there are many interference waves.

Since the frequencies that can be used in the network are limited by the frequencies that can be used by earth stations that cause the most interference, a sufficient number of lines cannot be secured.

If more frequencies are used than the above limit, there are some earth stations that can communicate and some stations that cannot communicate due to interference conditions. Also, it is impossible to determine whether communication is possible without actually allocating a line, and thus connection reliability is lacking.

Since the state of interference changes with time, a case may occur where an available frequency becomes available and vice versa.

The present invention is intended to solve the above-described problems of the related art, and secures a satellite line that can be allocated to a maximum regardless of the interference situation at each earth station, and performs an allocation operation. It is an object of the present invention to provide a satellite channel demand assignment device capable of setting a channel reliably.

(Means and Actions for Solving the Problems) The feature of the present invention is that each earth station measures the interference situation with respect to itself, and collects the result in the satellite link management unit of the hub station, thereby reducing the interference situation of each earth station. The line is assigned according to the request.

(Embodiment 1) FIG. 1 shows a configuration of a satellite channel demand assignment device of a hub station according to a first embodiment of the present invention. Processing unit 1
2. It has a device control unit 14. As compared with the conventional device configuration, the function of the satellite link management unit 20 is different from that of the conventional satellite link management unit 13 of FIG.

In addition to the conventional channel assignment status table 16 as shown in FIG. 13, the satellite link management unit 20 also includes information (for example, a remote station setting information table 21) which takes into account the status of interference at each remote earth station as shown in FIG. ). In the example of FIG. 2, the number of satellite links (for example, the bandwidth obtained by dividing the bandwidth of the satellite transponder by the channel arrangement interval) that can be used in the entire system is N, and the number of remote earth stations is M. Let Lm be the upper limit of the number of lines that can be actually allocated at the hub station. Lm is a modem installed in the hub station
It is determined by the number of 15 or the like, and generally Lm ≦ N. Also, since the demand assignment device is for sharing a satellite link between many earth stations, N <M, and the M / N is 10 to several tens depending on the type of traffic. The values in FIG. 2 are index values indicating whether or not a certain channel (frequency) can be used in a certain earth station, where 1 indicates usable and 0 indicates unusable. Here, the value is expressed by binary values of 1 and 0, but the algorithm of the line allocation described below is basically the same in the case of multi-values and continuous values. In the first embodiment, this table is basically fixed, and is rewritten when a remote earth station is installed or when the interference situation changes.

Taking a case where a line allocation request for a certain earth station (#k) is generated as an example, a remote station setting information table (hereinafter, the values of the table are represented by Xij, i is the earth station number, and j is the line number) is used. An example of the algorithm of the allocated line will be described.

Check the line assignment status table, find the set of unused line numbers as C1, and the line is not assigned (no communication)
Let E be the set of earth station numbers.

The remote station setting information table is checked, and a set of line numbers usable in the #k earth station is set to C2.

In the following cases, since the line cannot be allocated, the allocation request is rejected.

(A) When Lm lines have already been allocated (b) C1∩C2 = Φ (empty set) j∈C1∩C2 Is calculated, and the line with the minimum Sj is assigned to the #k earth station. According to the assignment rule described here as an example, #
If an allocation request is issued to another earth station after the line is allocated to the k earth station, the possibility that the line can be allocated can be maximized.

Next, an example of a channel allocation algorithm using a remote station setting information table in a broadcast mode for simultaneously transmitting information to a plurality or all remote earth stations will be described.

(A) The line assignment status table is checked, and a set of unused line numbers is C1, and a set of earth station numbers to which no line is assigned (not communicating) is E. Let E2 be a set of a plurality of earth stations to be communicated, and let E3 be a stacked set of the extra set of set E2 and set E.

(B) Check the remote station setting information table, and check the # of the set E2.
A set of line numbers usable by k earth stations is Ck.

(C) In the following case, since the line cannot be allocated, the allocation request is rejected.

(C-1) When Lm lines have already been allocated (c-2) C1∩Ck = Φ (k∈E2) (d) If _k∩E2 (C1∩Ck) ≠ Φ, j∈∩ For the circuit j where _k∈E2 (C1∩Ck) Is calculated, and the line with the smallest Sj is assigned to the earth station of the set E2. Here, _{∈ k ∈X} Y _k indicates a product set of the set Y _k corresponding to k belonging to the set X.

(E) If _∈k∈E2 (C1∩Ck) = Φ, set E2 is divided into two sets E21 and E22. _{∈ k∈ E21} (C1∩ Ck) ≠ Φ
_And if _∩k∈E22 (C1∩Ck) ≠ Φ, j∈∩
For the circuit j where _k∈E21 (C1∩Ck) Is calculated, and the line with the smallest Sj is assigned to the earth station of the set E21. Also, the circuit j that is _{j∈∩k∈E22} (C1∩Ck)
about Is calculated, and the line with the smallest Sj is assigned to the earth station of the set E22.

(F) When the condition (e) is not satisfied, the set E2 is divided into three sets, and the same determination as the condition (e) is performed. In the same manner, the number of divisions is sequentially increased until the condition that can be assigned is satisfied.

According to the allocation rule described here as an example, after limiting the number of lines used in the broadcast mode as small as possible, when an allocation request is issued to another earth station after allocating a line to these earth stations In addition, it is possible to maximize the possibility of being assigned a line.

As described above, in the first embodiment according to the present invention, each remote earth station uses a method in which information (a remote station setting information table) in consideration of the situation of interference at each remote earth station is held by the satellite link management unit. Even in a situation where the lines available at the earth station are different from each other, the satellite lines can be efficiently allocated and used.

(Embodiment 2) FIG. 3 is a block diagram showing a satellite channel management unit in a second embodiment of the satellite channel demand assignment device according to the present invention. The satellite link management unit 20 of this embodiment has a line assignment status table 16 and a remote station setting information table 21 similar to those of the satellite link management unit 20 of the first embodiment. As shown in the figure, information on traffic status for each remote earth station (remote station traffic information table 23) is held. The traffic information in this table is an integrated value of the number of times of connection (the number of calls) to the earth station, an integrated value of the connection time to the earth station, and is updated every time a line is allocated. Go.

The remote station traffic information table 23 in the second embodiment (hereinafter, the value of the table is represented by Wi. I is the earth station number, and the larger Wi corresponds to the larger past traffic volume) is used. An example of an algorithm for line assignment will be described. The rules and symbols in the first embodiment are the same, and the following rules are used instead of the rules.

j∈C1∩ C2 Is calculated, and the line with the minimum Sj is assigned to the #k earth station.

According to the allocation rule described here as an example, #k
If an allocation request is issued to another earth station after a line is allocated to an earth station, it is possible to maximize the likelihood of being able to allocate a line, taking into account the past track record of using satellite links by each earth station. . Since the function of collecting traffic information is required, the traffic becomes more complicated than in the first embodiment. However, it is necessary to leave more possibility of circuit assignment to an earth station having a high probability of being used. It is possible, and the connection probability as a whole can be increased.

(Embodiment 3) FIG. 5 is a block diagram showing a satellite channel management unit in a satellite channel demand assignment device according to a third embodiment of the present invention. The satellite line management unit 22 of the present embodiment has a line allocation status table 16, a remote station setting information table 21, and a remote station traffic information table 23 similar to those of the satellite line management unit 21 of the second embodiment. . In addition to these, it holds information (IM table 25) on intermodulation as shown in FIG. 6, for example.

In an earth station that transmits multiple waves simultaneously, intermodulation (IM) occurs due to the nonlinear characteristics of the transmitter, and improperly arranging multiple waves will cause interference in the system. For example, even if the arrangement is arranged at even intervals, the influence of IM becomes a problem, but if another arrangement is adopted, the same number of waves may be used in some cases. IM table is
It holds the combination of the arrangement of the waves whose IM interference level is within the allowable range, and is basically fixed once the types of waves that may be used are determined. is there. FIG. 6 schematically shows a situation where a list of possible combinations of the line numbers when arranging Lm waves and possible combinations when arranging Lm-1 waves is listed.

An example of a channel allocation algorithm using an IM table in the third embodiment will be described. The rules and symbols in the first and second embodiments are the same.
Change to the rule below and do as follows.

It is C3 of a set of assignable line numbers included in a certain row of the IM table.

(A) All the assigned lines at that time can be assigned in that line. (B) It is determined whether the two conditions of C1∩C2∩C3 ≠ Φ are satisfied. A set of rows with the largest number of lines that can be allocated simultaneously among rows that satisfy this condition
For C3, j∈C1∩ C2∩ C3 Is calculated, and the line with the minimum Sj is assigned to the #k earth station.

According to the allocation rule described here as an example, it is possible to allocate a line to the #k earth station on condition that the interference level due to IM falls within an allowable range. In addition, when an allocation request is issued to another earth station after allocating a line to the #k earth station, the possibility of allocating the line is maximized in consideration of the past satellite line use results of each earth station. can do.

(Embodiment 4) FIG. 7 is a block diagram showing a satellite channel management unit in a fourth embodiment of the satellite channel demand assignment device according to the present invention. The satellite line management unit 26 of the present embodiment has a line allocation status table 16, a remote station setting information table 21 and a remote station traffic information table 23 similar to the satellite line management unit 22 of the second embodiment. In addition to these, it holds information on the reservation service (reservation table 27). In the first to third embodiments, a request for setting a satellite channel is generated as needed, and is limited to a so-called immediate service in which it is determined from the assignment status at that time whether or not the request can be satisfied. In the present embodiment, in addition to the immediate service, a reservation service for making a connection at a certain time is simultaneously provided. The contents of this reservation table are, for example, as shown in FIG. 8 and include the time at which the line needs to be set and the number of the earth station, and are rewritten when the reservation is made and when the reservation is completed. Although such a reservation table is conventionally held in a system for performing a reservation service, the feature of the present embodiment is that the remote station setting information table 21 described in the first embodiment is also managed and line allocation is performed. Where to do.

An example of an algorithm for line allocation using the remote station setting information table 21, the remote station traffic information table 23, and the reservation table 27 will be described. The rules and symbols in the first embodiment and the second embodiment are the same, and the following rules are replaced with the following rules.

When a reservation occurs, it is determined whether or not a line can be allocated without inconsistency with an existing reservation. If it is not possible, the reservation will not be accepted. This determination problem can be solved as an assignment problem for the reservation target earth station using the remote station setting information table.

Assuming that the average line connection continuation time in this system is T and the margin coefficient is K1 (K1> 1), a set of earth stations whose time until the reservation start time is T × K1 or less in the reservation table is set to E3 and set E3. A set of lines to be allocated
And There are at least one combination of line assignments due to the following conditions, and usually a plurality of combinations. That is, there are a plurality of sets C4. For this plurality of sets C4, j∈C1
∩ C2∩ C4 ^C Is calculated to obtain a set C4 and j in which the minimum value of Sj is the maximum,
Assign #j line to #k earth station. Note that the set C4 ^C indicates a coset of the set C4.

According to the allocation rule described here as an example, when an allocation request is issued to another earth station after allocating a line to the #k earth station while securing a line for a reservation service, each earth station in the past is There is a feature that the possibility of assigning a line can be maximized in consideration of the satellite track record.

(Embodiment 5) In the first to fourth embodiments of the present invention, the remote station setting information table 21 held by the satellite link management units 20, 22, 24, 26 is basically fixed, and It is rewritten off-line when an earth station is installed or when the interference situation changes. In the fifth embodiment, the state of interference is measured at each remote earth station as needed, and the result is transferred to the hub station.
Is rewritten online. Ninth
The figure shows the configuration of a satellite channel demand assignment device of a remote station according to a fifth embodiment of the present invention. The signaling processing unit 11 and the call processing unit 1 are the same as the conventional device (FIG. 11).
2. It has a device control unit 14. The difference from the conventional device configuration is that an interference status measuring unit 30 is provided.

First, an example of a method of measuring the interference situation will be described with reference to FIG. The interference situation measuring section 30 holds a channel interference situation table 31 corresponding to one row in FIG. The control unit 32 of the interference state measuring unit 30 instructs one demodulator 17 of the modem 15 not used for communication at that time to receive the #j line. Here, when demodulation has been performed, it is determined that the #j line is in use in this system, and information indicating that the #j line is being used is set in the column of the #j line in the channel interference status table 31. If demodulation cannot be performed, the frequency of the interference level measurement circuit 33 is set to the reception frequency of the #j line, and the level is measured. The value of the measurement level itself or the result of determining whether communication is possible or not is set in the #j line column of the channel interference status table 31. As the interference level measurement circuit 33, a C / N measurement circuit or a baseband detection circuit is used. The above measurement is performed for all the lines, and the channel interference status table 31 is updated.

An example of a method of transferring the contents of the updated channel interference status table 31 to the hub station and updating the remote station setting information table 21 held in the hub station will be described. When a remote station issues a satellite channel assignment request to a hub station, it is normal to use a dedicated line for assignment request (called a request channel). Table in this request channel
31 information is transferred to the hub station. There are several methods for the timing of this transfer. In the first method, when a change occurs in the channel interference status table 31, the remote station transfers the content to the hub station at its own timing. In the second method, the hub station polls the remote station, and the remote station transfers the data to the hub station accordingly. The former has a feature that can quickly respond to changes in the situation of interference, and the latter has a hub station that collects information on the interference situation and can easily control the entire system.

As described above, in the fifth embodiment according to the present invention, each remote station has the interference status measuring unit 30, and the measurement result is transferred to the hub station, whereby the remote station holds the interference status measuring unit 30. The method of updating the station setting information table 21 solves three problems that occur when the conventional satellite channel demand assignment device is used in a situation where there are many interference waves.

(Effects of the Invention) As described above, according to the present invention, the satellite channel demand allocating apparatus according to the present invention retains the state of the unnecessary interference wave different in each remote earth station in the apparatus, thereby achieving the network The number of lines that can be used in the system can be secured more than in the case of the conventional device. Further, in the conventional device, communication reliability is determined because it is determined whether communication is possible after the line is allocated.However, the device according to the present invention considers the interference situation of each remote station in the allocation operation algorithm. When the assignment operation is performed, the line can be surely set.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a hub station device according to a first embodiment of the present invention, FIG. 2 is a diagram showing an example of the contents of a remote station setting information table, and FIG. 3 is a second embodiment of the present invention. FIG. 4 is a view showing an example of the content of a traffic information table in the embodiment; FIG. 4 is a diagram for explaining an example of the contents of a traffic information table; FIG. FIG. 6 is a diagram for explaining an example of the contents of an intermodulation table, FIG. 7 is a diagram showing the configuration of a satellite channel management unit in a fourth embodiment of the present invention, and FIG. FIG. 9 is a diagram illustrating an example of the contents of a table, FIG. 9 is a diagram illustrating a configuration of a remote station device according to a fifth embodiment of the present invention, FIG. 10 is a diagram illustrating details of an interference situation measuring unit, FIG. The figure shows the hub of a conventional satellite line demand allocation device Shows a side configuration, FIG. 12 illustrates a remote station-side configuration of a conventional satellite channel demand assignment device, FIG. 13 is a diagram for explaining an example of the contents of line allocation status table. 11 signaling processing unit, 12 call processing unit, 14 device control unit, 15 modulator / demodulator, 16 channel assignment status table, 20, 22, 24, 26 satellite link management unit 21 … Remote station setting information table, 23… Traffic information table, 25… Intermodulation table, 27… Reservation table, 30… Interference status measurement unit, 31… Channel interference status table, 32… Control unit, 33 ... Interference level measurement circuit.

Continuation of the front page (72) Inventor Toshiharu Kimura 2-3-2 Nishi Shinjuku, Shinjuku-ku, Tokyo International Telegraph and Telephone Corporation (56) References JP-A-3-274829 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H04B 7/14-7/22

Claims (5)

(57) [Claims] 1. A signaling processing unit for receiving and processing demand assignment requests from terminals connected to a plurality of remote earth stations and hub earth stations, managing the use status of a satellite line, and responding appropriately to the demand assignment requests. A satellite line management unit for allocating a line, a call processing unit for managing the state of a call and performing processing according to a call state such as a calling process and a disconnection process, and transmitting a communication signal to a satellite according to an instruction from the call processing unit. A satellite channel demand allocation device comprising a device control unit for controlling the frequency setting of the modem and the carrier on / off for transmitting to the hub earth station for performing allocation management of the satellite channel, Remote station setting information for holding information indicating, for each frequency to be used, an interference situation in the plurality of remote earth stations that issues a line allocation request to the hub earth station in a satellite link management unit; Provided line allocation status table holding information for managing the status of the table and the line allocation, a satellite line demand assignment apparatus characterized by performing the line allocation process using this information. 2. The hub earth station according to claim 2, wherein said remote station setting information table receives, from said plurality of remote earth stations, level information of an interference wave at said remote earth station for each frequency to be used, said hub earth station receiving said level information. Updated based on
2. The satellite channel demand allocating apparatus according to claim 1, wherein said table is a table for storing information indicating said interference status for each scheduled frequency. 3. The satellite link demand according to claim 1, further comprising a remote station traffic information table for holding traffic information for accumulating link allocation result data on said plurality of remote earth stations. Assignment device. 4. The satellite channel demand allocating apparatus according to claim 1, wherein said satellite channel management unit further comprises an intermodulation information table for holding information on an intermodulation value based on a frequency array. 5. The satellite channel demand allocating apparatus according to claim 1, wherein said satellite channel management unit further comprises a reservation table for holding information on a reservation service.