JP4196878B2 - COMMUNICATION BAND ALLOCATION METHOD, SYSTEM, AND DEVICE - Google Patents

Description

  The present invention relates to a frequency band allocation method for a satellite communication system, and a communication system and a management apparatus using the method.

  As reservations for frequency band allocation in a satellite communication system, reservations with end times specified (hereinafter referred to as schedule reservations) and reservations with no end times specified (hereinafter referred to as continuous reservations) are provided. When these two reservation methods are mixed, the frequency band may not be used effectively.

  For example, in a satellite communication system that manages a band that can accommodate up to four channels from channel 0 to channel 3, continuous reservation and schedule reservation that occupy one channel occur alternately four times, and channel 0 and channel 2 continue reservation. And channel 1 and channel 3 are assigned to schedule reservation. When the continuation reservation that occupies channel 0 and channel 2 ends, the schedule reservation that occupies every other channel is placed in a so-called “missing” state, and then a continuation reservation that occupies 2 channels occurs. In this case, the continuous reservation is not assigned to the continuous reservation even though the bandwidth is free for two channels, resulting in a call loss.

  In order to avoid the above situation, a method has been proposed in which a dedicated band for schedule reservation and a dedicated band for continuous reservation are separated in advance (see Non-Patent Document 1).

  However, in the method of dividing the bandwidth in advance, it is necessary to predict the rate at which each reservation occurs, and to allocate the bandwidth in advance based on the predicted value. For example, when schedule reservations are concentrated against expectations, there is a situation in which bandwidth cannot be allocated due to lack of bandwidth for schedule reservation even though the bandwidth for continuous reservation is free, and call loss and Not only will the frequency utilization efficiency decrease.

  In addition, when the frequency position that can be allocated is restricted by the frequency band for which the reservation is requested, the frequency accommodation efficiency is further deteriorated.

For example, a multi-rate / multi-carrier modem is a modulation / demodulation device that realizes one-carrier transmission of various bandwidths and simultaneous reception of a plurality of carriers of various bandwidths at a low cost. This is sometimes referred to as ²ⁿ bandwidth constraint. There are two types of ²ⁿ bandwidth constraints: bandwidth constraints and placement constraints.

FIG. 1 is a diagram illustrating an example of ²ⁿ bandwidth restriction.

  The bandwidth restriction means that the bandwidth that can be set in the modem is limited to a power of 2. Therefore, as shown in FIG. 1, the bandwidth is limited to a continuous bandwidth of 1, 2, 4 channels, and a bandwidth of 3 channels or 5 channels cannot be reserved.

When the occupied bandwidth is n channels, the possible channel positions are limited to the band for n channels from channel n × a (a = 0, 1,...) When the channel number is 0. It is to be done. As shown in FIG. 1 , for a band having 8 channels, a continuous band of 2 channels can only be assigned to a band of 2 channels from channel numbers 0, 2, 4, 6 respectively, and channel 3 and channel 4 Cannot be assigned to two consecutive channels. Similarly 4 continuous band channel, the bandwidth of the four channels of channel 0-3 or channel 4-7 is susceptible assignment, as shown in Figure 1, the channel 1-4 4 channels It cannot be assigned to a band.

Kikuchi, Tsuchida, Kawazoe, Kazama, “Development of Highly Efficient Line Control Program for Direct Multicast Satellite Communication System”, IEICE Technical Report SAT2002-159, P7-12

  In a satellite communication system using a modem with the above restrictions, such as a multirate / multicarrier modem, in order to effectively use the frequency, it is necessary to manage and operate the band in consideration of the above restrictions. In order to eliminate tooth loss, a bandwidth allocation method that secures the maximum continuous bandwidth is not sufficient.

Therefore, according to the present invention, under the bandwidth limitation of ²ⁿ , the omission due to the mixed handling of the schedule reservation and the continuous reservation is eliminated as much as possible, and the situation where the allocation becomes impossible even if there is a free capacity is eliminated as much as possible. It aims to provide a way to do.

  It is another object of the present invention to provide a management apparatus used in the above method and a satellite communication system using the above method.

According to the frequency band allocation method of the present invention,
In the frequency band allocation method for a new reservation in a satellite communication system having ²ⁿ bandwidth restrictions, if the end time is specified in the new reservation, it is determined whether or not the new reservation can be placed, and if the placement is impossible, or When the end time is not specified for the new reservation, the rearrangement step for performing the rearrangement of the registered reservation that has already been placed and the placement of the new reservation is executed, and the rearrangement step ends the reservation period of the new reservation. A first step of calculating a relocation target period including a reservation period of a new reservation by expanding based on an average value of the reservation periods of registered reservations with a specified time, and at least part of the relocation target period such out of registration reserved, the start time is extracted later is registered reserved than the processing time for performing the bandwidth allocation process for introduction of new reservation, redistribution the extracted registered reservation and new reservation A second step of the location target reservation, all relocated reservation, with a whether positionable under the band restriction of 2 ⁿ have a third step of determine a constant, the third The determination in the step is that all relocation target reservations are elements of the set U, and the first reservation with the longest reservation period is selected from the set U when the bandwidth is the narrowest and the same bandwidth. If there is a second reservation with the same bandwidth as the first reservation and the reservation period is within the reservation period of the first reservation, the first reservation and the second reservation are subject to ²ⁿ bandwidth constraints. Place them in consecutive channels and exclude the first and second reservations from set U, and if there is no second reservation, exclude the first reservation from set U and make it an element of set V After the addition is repeated and the set U becomes empty, the relocation target reservation included in the set V And performing by arranging in sequence.

According to another embodiment of the frequency band allocation method of the present invention,
For the relocation target period, the average value of the reservation periods of registered reservations with end times specified is obtained, the start time of new reservations is advanced by a period based on the average value, and the end time of new reservations is calculated as the average value. It is also preferable to calculate by delaying by a period based on .

According to the schedule management device of the present invention,
In a schedule management device of a satellite communication system having ²ⁿ bandwidth constraints, a new reservation can be placed if a storage means for holding information about a registered reservation that has already been placed and an end time is specified for the new reservation. If it is impossible to place, or if the end time is not specified for a new reservation, it is provided with bandwidth allocation means for relocating registered reservations and placing new reservations. In the re-arrangement of the existing reservation and the arrangement of the new reservation, the bandwidth allocating means expands the reservation period of the new reservation based on the average value of the reservation periods of the registered reservations with the designated end time. Calculate the relocation target period that includes the period, and among the registered reservations that are partly in the relocation target period, the start time is after the processing time point when the bandwidth allocation process for the new reservation is performed In it extracts the registered reservation, extracted and registered reservation and relocated Book new reservation, all relocated reservation, determine the constant with the whether positionable under the band restriction of 2 ⁿ The determination as to whether or not all the relocation target reservations can be arranged is performed by setting the all relocation target reservations as elements of the set U, and the reservation period when the bandwidth is the narrowest and the same bandwidth from the set U. If the second reservation with the same reservation bandwidth as the first reservation and the reservation period within the reservation period of the first reservation exists, Place the second reservation on a continuous channel according to ²ⁿ bandwidth constraints, exclude the first reservation and the second reservation from set U, and if there is no second reservation, Included in set V after set U is emptied by repeatedly excluding it from set U and adding it to the elements of set V The relocated reservation that is characterized by placing a thin order of bandwidth.

According to another embodiment of the schedule management apparatus of the present invention,
For the relocation target period, the average value of the reservation periods of registered reservations with end times specified is obtained, the start time of new reservations is advanced by a period based on the average value, and the end time of new reservations is calculated as the average value. It is also preferable to calculate by delaying by a period based on .

According to the satellite communication system of the present invention,
A plurality of satellite earth stations, a communication satellite, a satellite channel control device, and the schedule management device, wherein the schedule management device can communicate with the satellite channel control device, and the satellite channel control device includes the schedule Based on an instruction from a management device, a carrier necessary for communication between the satellite earth stations is set in the communication satellite.

According to the frequency band allocation method of the present invention, tooth loss caused by mixing and handling schedule reservations and continuous reservations is eliminated as much as possible by rearrangement, and ²ⁿ band constraints are imposed by a reservation selection method in rearrangement processing. By avoiding as much as possible, it is possible to efficiently use the frequency and to provide a high-quality service with little call loss at the time of schedule registration.

  The best mode for carrying out the present invention will be described in detail below with reference to the drawings.

  FIG. 2 is an example of a configuration diagram of a satellite communication system according to the present invention.

  According to FIG. 2, the satellite communication system includes a plurality of satellite earth stations 1, a communication satellite 2, a line control device 3, a schedule management device 4, and one or more reservation terminals 5. The schedule management device 4 can communicate with the line control device 3 and the reservation terminal 5.

  The line control device 3 has a function of setting a carrier necessary for communication between the satellite earth stations 1 via the communication satellite 2 based on an instruction from the schedule management device 4. The reservation terminal 5 has a function of inputting a schedule reservation and a continuous reservation to the schedule management device 4.

The satellite earth station 1 is configured by a multi-carrier / multi-rate modem and is subject to ²ⁿ bandwidth restrictions.

  The schedule management device 4 includes a communication unit 41, a bandwidth allocation unit 42, and a storage unit 43. The storage unit 43 stores data on the reservation status of schedule reservation and continuous reservation. The communication unit 41 performs communication processing with other devices such as accepting a new reservation input from the reservation terminal 5 and a new setting instruction for the satellite line control device 3.

  When a new reservation is entered, the bandwidth allocation unit 42 refers to the reservation status stored in the storage unit 43 and performs a bandwidth allocation process based on the allocation method of the present invention. If the bandwidth can be allocated as a result of the processing, the reservation is accepted and the storage unit 43 is updated. If the assignment is not possible, the reservation will be rejected. Acceptance or rejection is notified to the reservation terminal 5 via the communication unit 41. Further, based on the registered reservation stored in the storage unit 43, information necessary for a carrier to be newly set between the satellite earth stations 1 via the communication satellite 2 and the satellite channel control device 3 via the communication unit 41. It also has a function to notify

  FIG. 3 is a flowchart of the bandwidth allocation method of the present invention.

  (S301) When a new reservation is entered, it is first determined whether the reservation is a continuous reservation or a schedule reservation.

  (S302, S303) If the new reservation is a schedule reservation and there is an available bandwidth in the requested time zone, the allocation is performed as it is.

  (S304) If the reservation is a continuation reservation, or if it is a schedule reservation but cannot be assigned in S302, the registered reservation is rearranged.

  (S305, S306, S303) As a result of the rearrangement process, if the allocated bandwidth of the new reservation can be secured, the allocation is performed. If the allocated bandwidth cannot be secured, the reservation is not accepted.

  FIG. 4 is a flowchart of the rearrangement process.

  (S401) First, the processing target period of the rearrangement process is calculated by the method described later.

  (S402) Some of the reservations within the relocation processing period calculated in S401 are extracted and set as a set U. However, those already assigned at the time of processing are excluded.

  (S403) The processes of S403 to S408 are repeated until the set U becomes empty.

  (S404) From the set U, the reservation with the narrowest bandwidth and the longest reservation period is extracted as the reservation A.

  (S405) A reservation that has the same bandwidth as that of reservation A and whose reservation period is within the reservation period of reservation A is extracted as reservation B.

(S406, S407) When reservation B exists, reservation A and reservations included in reservation B are rearranged, and the rearranged reservation is excluded from reservation U. The reservation A and the reservation B are arranged in continuous channels in accordance with the ²ⁿ bandwidth restriction. That is, when the total bandwidth of the reservation A and the reservation B is m channels, it means that they are continuously arranged from the channel m * a (a = 0, 1,...).

  (S406, S408) When reservation B does not exist, reservation A is set as a single reservation and excluded from set U in addition to set V.

  (S409) After the set U becomes empty, the reservations of the set V are rearranged in the vacant bands in ascending order of the band.

  (S410) When all the reservations of the set V can be rearranged, the rearrangement result is confirmed (S411). When the rearrangement cannot be performed, all the previous rearrangements are restored (S412).

  The above-described allocation process will be described with reference to FIGS. According to FIG. 6, Reservation 1, Reservation 2 and Reservation 3 each occupying 1 channel are already set, and a schedule reservation occupying 2 channels is input as a new reservation. The reservation period of the new reservation overlaps with reservation 1 and reservation 2.

  In S302, since there is no continuous 2-channel vacancy in all the time slots of the new reservation period, the process proceeds to S304, and rearrangement processing is performed.

  In S401, the rearrangement target period is calculated at the beginning of the rearrangement process. Here, it is assumed that the period including reservations 1, 2, and 3 is calculated as shown in FIG. Accordingly, reservations 1, 2, 3, and new reservations are added to the set U in S402.

  In the first iterative process, reservation 2 with the narrowest bandwidth of 1 channel and the longest reservation period is extracted as reservation A in S404. In S405, the reservation 1 having the same bandwidth as the reservation 2 extracted as the reservation A and falling within the reservation period of the reservation 2 is extracted as the reservation B. In S407, reservation 1 and reservation 2 are rearranged. Here, the arrangement is performed in the continuous band of channel 0 and channel 1, and the first iteration is completed. At this time, the reservation 3 and the new reservation remain in the set U.

  In the second iteration, reservation 3 is extracted as reservation A in S404. Since there is no reservation having the same bandwidth as reservation 3, reservation 3 is added to set V as a single reservation in S408.

  In the third iteration, the new reservation is added to the set V as a single reservation, and the set U becomes empty.

  In S409, single reservations included in the set V are arranged. First, reservation 3 having a small bandwidth is arranged. Since reservation 2 has already been allocated to channel 0, it is allocated to channel 1 here. Subsequently, a new reservation is arranged on two consecutive channels of channel 2 and channel 3. FIG. 8 is a diagram showing a reservation status after rearrangement.

  FIG. 5A is a flowchart for calculating a rearrangement target period performed in S401 of the rearrangement process, and FIG. 5B is an explanatory diagram of the rearrangement target period.

  As shown in FIG. 5B, the new reservation start time is Ts, and the end time is Te. Further, the start time of the rearrangement target period is T1, and the end time is T2.

  (S501) The average value t of the reservation period of the schedule reservation currently registered is calculated.

  (S502) The parameter T is calculated as T = N × t using a preset integer value N. The integer value N set in advance is a value that can be changed during operation, and is determined by a trade-off between an increase in accommodation efficiency due to the expansion of relocation targets and an increase in processing time required for relocation. The

  (S503) It is determined whether or not the value of Ts-T is before the current time.

  (S504, S505) The start time T1 of the relocation target period is Ts-T when Ts-T is after the current time, and is the current time when it is before the current time.

  (S506) The end time T2 of the relocation target period is calculated by Te + T.

FIG. 1 is a diagram illustrating an example of band limitation of ²ⁿ . It is a block diagram which shows the example of the satellite communication system by this invention. FIG. 3 is a flowchart of the bandwidth allocation method of the present invention. FIG. 4 is a flowchart of the rearrangement process. It is a flowchart of a rearrangement object period calculation process. It is explanatory drawing of the rearrangement object period. It is explanatory drawing which shows the example of the band allocation method by this invention. It is explanatory drawing which shows the example of the band allocation method by this invention. It is explanatory drawing which shows the example of the band allocation method by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Satellite earth station 2 Communication satellite 3 Line control apparatus 4 Schedule management apparatus 41 Communication part 42 Band allocation part 43 Memory | storage part 5 Reservation terminal

Claims (5)

In a frequency band allocation method for a new reservation of a satellite communication system having 2 ⁿ band constraints,
When the end time is specified for the new reservation, it is determined whether or not the new reservation can be arranged. When the arrangement is impossible, or when the end time is not specified for the new reservation, the registered reservation that has already been arranged is re-read. Perform a relocation step to place and place a new reservation,
The relocation step includes:
A first step of calculating a relocation target period including the reservation period of the new reservation by expanding the reservation period of the new reservation based on the average value of the reservation periods of the registered reservations with designated end times;
Of the registered reservations that are partly in the relocation target period, the registered reservations whose start time is after the time of the bandwidth allocation process for the input of the new reservation are extracted, and the extracted registered reservation and new reservation are extracted A second step in which the reservation is a relocation target,
All relocated reservation, a third step of determine the constant with the whether positionable under the band restriction of 2 ^n,
Only including,
The determination in the third step is
All reservations to be relocated are elements of set U. If the bandwidth is the narrowest and the same bandwidth from set U, the first reservation with the longest reservation period is selected, and the first reservation If there is a second reservation with the same bandwidth and a reservation period that is within the reservation period of the first reservation, the first reservation and the second reservation are placed in a continuous channel according to the ²ⁿ bandwidth constraint. Repeatedly excluding the first reservation and the second reservation from the set U, and if the second reservation does not exist, excluding the first reservation from the set U and adding to the elements of the set V; A method in which after the set U becomes empty, the relocation target reservations included in the set V are arranged in ascending order of bandwidth.   For the relocation target period, the average value of the reservation periods of registered reservations with end times specified is obtained, the start time of new reservations is advanced by a period based on the average value, and the end time of new reservations is calculated as the average value The method according to claim 1, wherein the calculation is performed by delaying by a period based on. In a schedule management apparatus for a satellite communication system having ²ⁿ bandwidth constraints,
Storage means for holding information about registered reservations that have already been placed;
When the end time is specified in the new reservation, it is determined whether or not the new reservation can be arranged.When the arrangement is not possible, or when the end time is not specified in the new reservation, Bandwidth allocation means for placing new reservations;
With
The bandwidth allocation means in the rearrangement of registered reservations and new reservations
By expanding the reservation period of a new reservation based on the average value of the reservation periods of registered reservations with an end time specified, the relocation target period that includes the reservation period of the new reservation is calculated, and the relocation target period of some in such also registered reserved, the start time is extracted later is registered reserved than the processing time for performing the bandwidth allocation process for introduction of new reservation, extracted registered reservation and relocated Book new reservation and then, all relocated reservation, and determine the constant with the whether positionable under the band restriction of 2 ^n,
To determine whether all relocation reservations can be placed,
All reservations to be relocated are elements of set U. If the bandwidth is the narrowest and the same bandwidth from set U, the first reservation with the longest reservation period is selected, and the first reservation If there is a second reservation with the same bandwidth and a reservation period within the reservation period of the first reservation, the first reservation and the second reservation are arranged in continuous channels according to the ²ⁿ bandwidth constraint. Repeatedly excluding the first reservation and the second reservation from the set U, and if the second reservation does not exist, excluding the first reservation from the set U and adding it to the elements of the set V; An apparatus that performs reservation by arranging the relocation target reservations included in the set V in ascending order of bandwidth after the set U becomes empty. For the relocation target period, the average value of the reservation periods of registered reservations with end times specified is obtained, the start time of new reservations is advanced by a period based on the average value, and the end time of new reservations is calculated as the average value. The apparatus according to claim 3 , wherein the calculation is performed by delaying by a period based on. In a satellite communication system comprising a plurality of satellite earth stations, a communication satellite, a satellite line control device, and the schedule management device according to claim 3 or 4 ,
The schedule management device can communicate with the satellite line control device,
The satellite communication system is configured to set a carrier necessary for communication between the satellite earth stations to the communication satellite based on an instruction from the schedule management device.

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