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INVESTIGATION OF THE DEPENDENCE OF THE INFORMATION DELIVERY EFFICIENCY ON THE PRODUCTIVITY OF THE EARTH REMOTE SENSING SPACECRAFT
DOI 10.24411/2072-8735-2018-10333
Leonid V. Kurahtenkov,
MTUCI, Moscow, Russia, lkurakht@srd.mtuci.ru
Denis S. Chirov,
MTUCI, Moscow, Russia, chirov@srd.mtuci.ru
Victoria V. Domozhakova,
MTUCI, Moscow, Russia
Keywords: space systems, the Earth remote sensing, simulation, productivity, efficiency.
Systems and products of rocket and space technology are complex technical systems, the effectiveness evaluation of which involves various approaches. In relation to modern spacecraft and space systems for the Earth remote sensing, two important characteristics are considered: the productivity and the data delivery efficiency to ground-based infrastructure. These requirements in spacecraft engineering or in posteriori estimates of functioning spacecraft are often considered separately, while in reality they are closely relative. In article are considering the dependences of the satellite systems productivity on the data delivery efficiency for different spacecraft operation programs. During modeling of the Earth remote sensing spacecraft functions, two algorithms of prioritizing images for transmission to the information receiving point were considered: "queue" (the "oldest" image is transmitted first) and "stack" (the last received image is transmitted first). Simulation was performed in modeling software of satellite QSatStat systems functions, developed in MTUCI for the following conditions: spacecraft is on circular sun-synchronous orbit of 475km height, the size of one frame -2 GB, speed of high-speed radio link - 300 Mbit/s, two ground receiving information stations (Moscow and Ulan-Ude), the observation objects are located at the nodes of the equidistant (uniform) grid on the Earth's surface. The simulation results showed that the productivity of the Earth remote sensing spacecraft significantly depends not only on the speed of images delivery, but also on the selected algorithm of prioritizing of information transmitting to the information receiving point. In dependents of the prioritization algorithm, the information delivery speed with the same productivity of the Earth remote sensing spacecraft can vary by a factor of 2-3.
Information about authors:
Leonid V. Kurahtenkov, PhD, head of laboratory, MTUCI, Moscow, Russia
Denis S. Chirov, Grand Dr. in Engineering, chief researcher, MTUCI, Moscow, Russia
Victoria V. Domozhakova, software engineer, Moscow, Russia
Для цитирования:
Курахтенков Л.В., Чиров Д.С., Доможакова В.В. Исследование зависимости оперативности доставки информации от производительности КА ДЗЗ // T-Comm: Телекоммуникации и транспорт. 2019. Том 13. №12. С. 51-55.
For citation:
Kurahtenkov L.V., Chirov D.S., Domozhakova V.V. (2019). Investigation of the dependence of the information delivery efficiency on the productivity of the earth remote sensing spacecraft. T-Comm, vol. 13, no.12, pр. 51-55.
Introduction
Any space system (SS) is designed in accordance with the tactical and technical task (TTT), which defines the tactical and technical characteristics (TTC) for this system. For the Earth remote sensing (ERS) SS in particular for optoelectronic observation spacecrafts (SC) the following requirements are imposed for target characteristics:
- requirements for reviewing a latitude ranges (global or limited);
- requirements for shooting modes;
- requirements for observation details and spectral ranges;
- requirements for the observation frequency;
- requirements for the speed of information delivery;
- requirements for system or SC productivity;
- requirements regarding economic issues, the period of active existence, etc.
These requirements are often set separately, while in reality they are closely interconnected. Indeed, while requirements for image quality are going down, the field of view is rising up, which means that the observation frequency is improving (decreasing). Observation frequency is the time between successively observations of possible objects on the Earth's surface. The connection between the information delivery speed and SC productivity is less obvious.
The efficiency indicator of information delivery is measured in units of time and can include (by summing, depending on the approaches) particular indicators of efficiency: the lime for setting the task, the time for setting up the usable shooting program for the SC, the time for processing the received information at the ground infrastructure facilities, etc. But all different approaches of determination this indicator are united by what it includes plus significant part of the time from shooting the observation object to the data delivery via high-speed radio link (HSRL) to the information receiving point (1RP). It is the way how the efficiency indicator of information delivery will be considered in this article.
As a productivity indicator of the observation space system, will considered the number of objects that the SC can shoot and delivery information to the IRP for some time interval (loop, day, year) of the flight. This indicator primarily depends on the number of applications for shooting objects, the SC's possibilities for shooting objects, the period of entry into the radio visibility zone (RV2) of the PPI, and the data transmission speed via the HSRL. Moreover, when it comes to SC productivity, it is often overlooked that the delivery efficiency of all images which characterize productivity are generally different. This problem is especially acute when it comes to tasks in which strict requirements are placed on the inadmissibility of severe information aging. In this way, the study of the dependence of SC productivity on the information delivery speed is an important and actual task.
1. Analysis of the subject area state
The task of evaluating the information delivery speed to the IRP has been investigated for a long time. All researches in this subject area can be divided into two main directions. The first direction includes methods and algorithms for evaluating the efficiency of information delivery, taking into account the reliability of the SC ERS and IRP equipment [1, 2, 3J, and the second direction includes the evaluating of efficiency depending on the SS orbital construction [4, 5].
In particular, in fl], the problem of evaluating the information delivery speed via the HSRL of space systems ERS using the reliability ofthe HSRL and the channel frame volume is considered. A mathematical expression is proposed for estimating the information transmission time to the ground receiving point, which considers the influence ofthe channel frame volume and proves increasing ofthe estimation accuracy up to 60% in comparison with classical methods. The problem ofthe dependence of SC productivity on the information delivery speed is partially considered.
The influence of the reliability of the onboard systems of the SC ERS on the periodically shooting indicators is considered in [2, 3]. The authors proposed an estimation methodology based on simulation of the SC target functionality including on-board systems failures, and software that implements this technique. In [3] as an indicator of efficiency is considered one of the particular parameters, namely, the time from moment of starting shooting the investigated object to the moment when SC is entering radio visibility zone of ground IRP. The main aim of simulation in [2, 31 is to establish the dependence of the information delivery speed to the SC ERS reliability with fixed orbital parameters and the location of IRP. The influence of the tactics of the SC ERS work on the information delivery speed is not considered in this article.
In [4], an analysis ofthe construction ofthe SC ERS orbits is to provide local control ofthe Earth's surface area (the Middle East region). The authors proposed an original methodology for ensuring the solution of a problem using a single SC. The optimization of the SC ERS solar-synchronous orbit is carried out according to the criteria of observation repeatability in a certain area. To increase the observation repeatability, it is proposed to use the hardware reorientation and the SC itself in adjacent loops. Similar researches ofthe effectiveness of single missions of SC ERS were studied in |5| for the Mediterranean region.
In [6], the problem of SC ERS controlling is investigated to achieve the required quality of providing information for customers. It is shown that the development of ERS systems are required changes in the approach for planning their application. A multi-agent planning system has been proposed for controlling the perspective SC ERS. For the main criteria of the SC ERS productivity effectiveness are distinguished the following: the information delivery speed, the quality (resolution) of information and the cost of requests for information. The main idea in [6] is estimation of the SC ERS recovery time after failures or introducing new SC into the group.
2. Statement ofthe research problem
Despite the fact that the SC ERS productivity is rather complicated process, which is influenced by many factors, including random ones, it is possible to consider some simplified models. At the first we will consider a special case: due to high requirements on the relevance information, only the last picture taken before entering the RVZ ofthe IRP will fall under these conditions. In this case, the SC productivity on a certain modeling interval for the minimum (can be assumed that it is zero) information delivery efficiency is equal to the number of SC's entries in the RVZ of the IRP - the same number of images will be transmitted via the HSRL, the rest of the images, due to the given conditions, weren't presented and weren't transmitted. The second particular case would be different, assumed that the re-
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quirements for the relevance information have not been established, i.e. during entering the RVZ of the 1RP all images from the SC on-board storage device (BSD) will be transmitted. At the beginning would be assumed that the distribution of objects, the conditions and the shooting program, the time of being in the RVZ of the 1RP and the speed of the HSRL are coordinated in such a way that the amount of memory of the BSD which is used by images is infinitely increase. Filling the memory of the BSD is shown in Figure 1.
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Figure 1. Filling the BSD memory of the SC with an excess number of shooted objects
This example of the non-optimal functionality of the SC ERS is interesting in that it gives the maximum evaluation of the SC's productivity: there are always images in the BSD memory, which means that receiving is making during all full sessions of being in radio visibility of the IRP - there can be no better productivity indicator for any obviously higher delivery efficiency. In this way, starts from a certain value the value of information delivery efficiency will become equal to the maximum and will not increase.
This value of information delivery efficiency is characterized by the fact that for any smaller value of information delivery efficiency over a long period of time, will be a moment when the memory of the SC's BSD will be completely freed, cause of captured images which will be transmitted to the !RP. This will happen during some communication session with IRP, and the rest part of this communication session the images will not be received, due to this, the productivity will be lower than the maximum possible.
Based on this important comment, we will perform modeling to establish the nature of the dependence of productivity on the information delivery efficiency in the interval between the minimum and maximum values. We will select the shooting conditions in such a way that, over a sufficiently long simulation interval, the memory of the BSD will be periodically free. An example of such a filling of the BSD is shown in Figure 2.
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Figure 2. Filling the memory of the SC's BSD with the number of shooted objects close to optimal - periodically there is a complete freeing of the BSD
3. Simulation results
Simulation was performed in software package QSatStat of modeling satellite systems functions, developed in MTUCI |7j. For a test object was chosen a SC in a solar-synchronous circular orbit with a height of 475 km. The parameters of special airborne equipment {matrix size, radiometric resolution) were chosen in the way that the size of one frame was about 2 GB. The speed of the HSRL was set equal to 300 Mbit/s, the model of the ground infrastructure was presented by two IRP located in Moscow and in Ulan-Ude. The objects of observation were located at the nodes of the equidistant (uniform) grid on the Earth's surface, their number (grid step) was the maximum possible, provided for the BSD memory for not being overloaded and periodically all the images could be transmitted. Simulation was performed for an interval of 2 months with a simulation step of 1 minute. At the same time, two algorithms of prioritizing images were considered for transmission to the IRP: "queue" (the "oldest" image is transmitted first) and "stack" (the last image received is transmitted first). In both cases, the total productivity amounted to 2014 objects, but the image delivery efficiency was distributed in different ways. The results of the image delivery efficiency are shown in table 1.
Table 1
Evaluations of image delivery efficiency with different prioritization algorithms
Image Priority Mill Average Max
Queue 34m in 2h 39m in ] Oil 20min
Stack 33min 2h 40m in 46h 7min
A more complete probabilistic characteristics of the distribution of image deliver»' efficiency are represented by a probability density estimate using histograms. Histograms of image delivery times for the "queue" and "stack" algorithms are shown in Figures 3 and 4, respectively.
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time deavwy
Figure 3. A histogram of times delivery for the "queue" algorithm
delivery time distribution
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Figure 4. A histogram of times delivery for the "stack" algorithm
Conclusion
Based on the received delivery time of each image, it is possible to draw a graph of dependence of the SC's productivity on the information delivery to the IRP. As noted earlier, for each of the prioritization algorithms, it will be different, but they will be combined with the maximum of productivity value equal to the number of objects during uninterrupted transmission while it is being in the RVZ of the IRP, which will be achieved for the maximum value of image delivery efficiency. These graphs are shown in Figure 5.
As can be seen from the graphs, the productivity significantly depends not oniy on the image delivery speed, but also on the selected algorithm for prioritizing the information transmitting to the IRP. Depends on the prioritization algorithm, the information delivery speed with the same productivity of SC ERS can vary by a factor of2-3.
oifonmation deKvay efficiency to thtPPI
Figure 5. Dependence of performance on the speed of delivery for various priorities of resetting images on the PPl
Analysis of the data dependencies confirms that the using meaning of "SC FRS productivity" excluding monitoring efficiency does not make sense, as well as the using the SC efficiency characteristics without productivity, that all are just a potential assessment for one specific observation object, but not characteristic of the all SC's capabilities. Based on received results, using "stack" prioritization is preferable for high requirements of delivery efficiency and using "queue" prioritization is preferable for high productivity requirements. The construction of a specific model for prioritizing information transmitting is one of (he important tasks of planning the SC ERS functions and depends on the specific needs for the consumer from the information from SC.
References
1. Kashcheev A.A. (2016). Evaluation of the information delivery efficiency via a high-speed radio link of space systems for the Earth remote sensing. Magazine of radioelectronics. No. 8, pp. 1-10.
2. Kirilin A.N., Akhmetov R.N., Kurenkov V.I., Kapitonov V.A., Strati I atov N.R., Lokhmatkin V.V. (2013). The cffcct of reliability of onboard systems of remote sensing spacecraft on the periodicity of shooting. Bulletin of the Samara State Aerospace University-, No. 4 (42), pp. 170-180.
3. Lokhmatkin V.V., Kurenkov V.I. (2014). Modeling the effect of failures of ERS onboard systems on indicators of the efficiency of information transfer. Bulletin of the Samara Scientific Center of the Russian Academy of Sciences. Vol. 16, No. I (2), pp. 429-434.
4. Ebrahiini A„ Mirshams M., Ali S., Moosavian S.A.A. (2019). Orbit analysis of a remote sensing satellite for local observation of the earth surface // https://www.researchgate.net/publiCatiSn/237325291 from 10.23.2019.
5. Ulivieri C., Laneve G., Hejazi SM. (1998). Orbit Design Analysis for Remote Sensing Satellite Constellations. Mission Design <£- Implementation of Satellite Constellations, pp. 237-242.
6. Skobelev P.O. et al. (2017). Application of multi-agenL technology in the scheduling system of swarm of Earth remote sensing satellites. Procedia Computer Science. 103 {2017), pp. 396-402.
7. Adjemov S.S., Kuchumov A.A. (2008). Universal complex of simulation modeling of "SatStat" satellite systems. T-Comm. No. 2, pp. 25-18.
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ИССЛЕДОВАНИЕ ЗАВИСИМОСТИ ОПЕРАТИВНОСТИ ДОСТАВКИ ИНФОРМАЦИИ
ОТ ПРОИЗВОДИТЕЛЬНОСТИ КА ДЗЗ
Курахтенков Леонид Владимирович, МТУСИ, Москва, Россия, lkurakht@srd.mtuci.ru Чиров Денис Сергеевич, МТУСИ, Москва, Россия, lchirov@srd.mtuci.ru Доможакова Виктория Викторовна, МТУСИ, Москва, Россия
Аннотация
Системы и изделия ракетно-космической техники представляют собой сложные технические системы, оценка эффективности которых предполагает различные подходы. Применительно к современным космическим аппаратам и космическим системам дистанционного зондирования Земли рассматривают две важные характеристики: производительность и оперативность доставки данных на объекты наземной инфраструктуры. Данные требования при проектировании КА, либо апостериорные оценки функционирующих КА зачастую рассматривают по отдельности, в то время как на самом деле они тесно взаимосвязаны. Рассматриваются вопросы зависимости производительности спутниковых систем от оперативности доставки данных при различных программах функционирования КА. При моделировании функционирования КА ДЗЗ рассматривались два алгоритма приоритезации снимков для передачи на ППИ: "очередь" (первым передается наиболее "старый" снимок) и "стек" (первым передается последний полученный снимок). Моделирование производилось в программном комплексе моделирования функционирования спутниковых систем QSatStat, разработанного в МТУСИ, для следующих условий: КА на солнечно-синхронной круговой орбите высотой 475 км, размер одного кадра -2 Гбайта, скорость высокоскоростной радиолинии -300 Мбит/c, два наземных пункта приема информации (Москва и Улан-Удэ), объекты наблюдения были расположены в узлах эквидистанциальной (равномерной) сетки на поверхности Земли. Результаты моделирования показали, что производительность КА ДЗЗ существенно зависит не только от оперативности доставки снимков, но и от выбранного алгоритма приоритезации сброса информации на пункт приема информации. В зависимости от алгоритма приоритезации, оперативность доставки информации при одинаковой производительности КА ДЗЗ может отличаться в 2-3 раза.
Ключевые слова: космические системы, дистанционное зондирование Земли, имитационное моделирование, производительность, оперативность.
Литература
1. Кащеев А.А. Оценка оперативности доставки информации по высокоскоростной радиолинии космических систем дистанционного зондирования земли // Журнал Радиоэлектроники, №8, 2016. С. 1-10.
2. Кирилин А.Н., Ахметов Р.Н., Куренков В.И., Капитонов В.А., Стратилатов Н.Р., Лохматкин В.В. Влияние надёжности бортовых систем космических аппаратов ДЗЗ на показатели периодичности съёмки // Вестник Самарского государственного аэрокосмического университета. №4 (42), 2013. С. 170-180.
3. Лохматкин В.В., Куренков В.И. Моделирование влияния отказов бортовых систем космических аппаратов ДЗЗ на показатели оперативности передачи информации // Известия Самарского научного центра Российской академии наук, том 16, № 1(2), 2014. С. 429-434.
4. Ebrahimi A., Mirshams M., Ali S., Moosavian S.A.A. Orbit analysis of a remote sensing satellite for local observation of the earth surface // https://www.researchgate.net/publication/23732529l от 23.10.2019.
5. Ulivieri C., Laneve G., Hejazi S.M. Orbit Design Analysis for Remote Sensing Satellite Constellations // Mission Design & Implementation of Satellite Constellations (1998), pp 237-242.
6. Skobelev P.O. et al. Application of multi-agent technology in the scheduling system of swarm of Earth remote sensing satellites / Procedia Computer Science 103 (2017), рp. 396-402.
7. Аджемов С.С., Кучумов А.А. Универсальный комплекс имитационного моделирования спутниковых систем "СатСтат" // T-Comm: Телекоммуникации и транспорт. 2008. № 2. С. 25-18.
Информация об авторах:
Курахтенков Леонид Владимирович, к.т.н., заведующий лабораторией, МТУСИ, Москва, Россия Чиров Денис Сергеевич, д.т.н., главный научный сотрудник, МТУСИ, Москва, Россия Доможакова Виктория Викторовна, инженер-программист, МТУСИ, Москва, Россия
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