The aerospace environment imposes straight opera- tive conditions so every electronic system usually needs to be validated for these. The same way, communica- tion systems need to be evaluated before their intro- duction in aerospace applications. In the paper we present a new methodology for the evaluation of com- munication systems in space applications. The meth- odology aims, by abstraction, at identifying all the critical aspects for the evaluation and at defining a standard and reusable framework in order to be appli- cable to any Communication Systems. The methodol- ogy has been applied for the evaluation of three Data Bus for satellite communications: 1553, 1-Wire and Profibus DP RS 485 based systems have been analyzed and evaluate

Di Carlo, Stefano

Elia, P.

Prinetto, Paolo Ernesto

Savino, Alessandro

Tiotto, Gabriele

English

The aerospace environment imposes straight opera- tive conditions so every electronic system usually needs to be validated for these. The same way, communica- tion systems need to be evaluated before their intro- duction in aerospace applications. In the paper we present a new methodology for the evaluation of com- munication systems in space applications. The meth- odology aims, by abstraction, at identifying all the critical aspects for the evaluation and at defining a standard and reusable framework in order to be appli- cable to any Communication Systems. The methodol- ogy has been applied for the evaluation of three Data Bus for satellite communications: 1553, 1-Wire and Profibus DP RS 485 based systems have been analyzed and evaluated

DI CARLO, STEFANO

PRINETTO, Paolo Ernesto

SAVINO, ALESSANDRO

TIOTTO, GABRIELE

Elia P.

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

05 August 2020POLITECNICO DI TORINORepository ISTITUZIONALEA Systematic Approach for Evaluating Satellite Communications Systems / Di Carlo S.; Prinetto P.; Savino A.; Tiotto G.;Elia P.. - STAMPA. - (2008), pp. 13-16. ((Intervento presentato al convegno IEEE 6th East-West Design & TestSymposium (EWDTS) tenutosi a Lviv, UA nel 9-12 Oct. 2008.OriginalA Systematic Approach for Evaluating Satellite Communications SystemsPublisher:PublishedDOI:Terms of use:openAccessPublisher copyright(Article begins on next page)This article is made available under terms and conditions as specified in the  corresponding bibliographic description inthe repositoryAvailability:This version is available at: 11583/1844479 since:IEEE Computer SocietyKHARKOV NATIONAL UNIVERSITY OF RADIOELECTRONICS    Proceedings of IEEE  East-West Design & Test  Symposium  (EWDTS’08)   Copyright © 2008 by The Institute of Electrical and Electronics Engineers, Inc.    SPONSORED BY  IEEE Computer Society Test Technology Technical Council               Lviv, Ukraine, October 9 – 12, 2008 IEEE EWDTS, Lviv, October 9-12, 2008 1A Systematic Approach for Evaluating Satellite Communications Systems   Stefano Di Carlo, Paolo Prinetto, Alessandro Savino, Gabriele Tiotto Politecnico di Torino, Dipartimento di Automatica e Informatica Email: {stefano.dicarlo, paolo.prinetto, alessandro.savino, gabriele.tiotto}@polito.it  Paola Elia Thales Alenia Space Email: paola.elia@thalesaleniaspace.com    Abstract  The aerospace environment imposes straight opera-tive conditions so every electronic system usually needs to be validated for these. The same way, communica-tion systems need to be evaluated before their intro-duction in aerospace applications. In the paper we present a new methodology for the evaluation of com-munication systems in space applications. The meth-odology aims, by abstraction, at identifying all the critical aspects for the evaluation and at defining a standard and reusable framework in order to be appli-cable to any Communication Systems. The methodol-ogy has been applied for the evaluation of three Data Bus for satellite communications: 1553, 1-Wire and Profibus DP RS 485 based systems have been analyzed and evaluated1.  1. Introduction  The high level of criticality and completeness de-manded by industry in the aerospace field requires the identification of an evaluation methodology able to validate aerospace-designed systems with high accu-racy, and to analyze those scenarios that may poten-tially impact their correct behavior. It is a matter of fact that the larger part of industry costs are represented by development expenses in validation and testing [1]. Satellites make large use of electronic devices with strong requirements in terms of physical space con-strains, and tolerance to radiations, vibrations, faults, and shock. In order to efficiently analyze potential sources of hazard in this type of systems, it is manda-                                                           1 This work has been made in collaboration with Thales Alenia Space for the validation of communication channels to be used in a satellite. The target systems are described above in the paper. tory to identify all the electrical and environmental conditions that may influence their behavior.  While the influence of these environmental factors is not always deducible a-priori using a theoretical ap-proach, it may be possible to provide proper tools al-lowing to better understand the impact of a set of fac-tors over the system, or a sub-part of it.  Several studies propose different solutions for vali-dating communication systems in satellites and avion-ics, developing methods for the verification at different abstraction levels: from the electrical and physical level to the protocol level, [1] [2]. The main drawback of these solutions is that they are mainly application dependent (e.g., terrestrial, avionics, space, etc.). Thus, the definition of an application independent methodol-ogy allowing the evaluation of a communication sys-tem at all abstraction levels, including the system level, is still a challenging problem.  In this paper we propose a new methodology for the analysis and validation of communication systems. It is based on the abstract definition of critical aspects of the system and the identification of the potential im-pact factors on them. The framework is studied to have modularity properties that are very useful whereas the evaluation will need different approaches.  Moreover, the abstract approach allows the methodology to be scenario independent.  This paper is organized as follows: Section 2 over-views the proposed methodology and a complete de-scription of its abstraction level is provided. In Section 3 the methodology is described, step by step, to show the entire workflow. Section 4 shows the experimental results when the methodology was applied for the vali-dation of three commercially available communication channels, namely 1553 Data Bus, 1-Wire and Profibus Decentralized Periphery (DP) RS485, [3] [4] [5]. Sec-tion 5 concludes the paper giving some future perspec-tive of the methodology. IEEE EWDTS, Lviv, October 9-12, 2008 13 2. Methodology Work Flow  For validation purpose, a generic Communication System can be modeled as a grey box containing a set of Inputs and a set of Outputs (the System Grey-Box Structure in Figure 1). The Inputs represent the set of controlling factors, internal or external at the system that may in turn influence the system behavior, e.g. environmental temperature, power supply voltage, etc., whereas Outputs represent the set of characteristics that are controlled or influenced someway by the inputs (all or a subset of). The way in which they are controlled or influenced can be available or derived by different. Hereinafter, we will refer to inputs as Impacting Factors (IPs) and to outputs as Features (Fs), (Figure 1).  The goal of the proposed validation methodology is to provide users a medium to understand how different Impacting Factor may influence the System under evaluations in terms of influence of the considered features. The proposed methodology is composed of several sequential steps, as follows:  1. Selecting the target Communication System. The communication system has to be properly defined in terms of standard, used devices, etc.; 2. Gathering all the Features. Features are ex-tracted by analyzing the system and by care-fully defining the aspects of the system that need to be validated. They can be clustered in classes that do not depend on a particular communication channel; 3. Identifying all the Impacting Factors. Using system designers experience and the system documentation (like the communication chan-nel standard, the target application, etc.) the Impacting Factors are identified; 4. Defining how each Feature may be influenced by IPs. Each feature F is investigated to definehow it is influenced by a subset of IPs; 5. Defining how Impacting Factors and Features shall be evaluated. Practical considerations on how the measurement campaigns have to be performed are made in order to obtain a scien-tific and structured way of work; 6. Performing the Measurement Campaigns. Once the campaigns are defined, they are made and all data is collected for the further evaluations.  3.  Methodology Description  In this section we exploit the methodology, step by step, in order to show how it was design for. We focus on terminology definitions and abstraction strategies.  3.1 Features and Impacting Factors identifica-tion  The identification of Features and Impacting Factors, as described above, requires a deep analysis of the tar-get system and scenario. Resorting to the system gray-box structure, the analysis has to be performed by gathering all the possible characterizations and con-strains from channel specifications, designer guidelines and data sheets. The IPs are mainly derived from con-siderations strictly connected with the operative condi-tions. Furthermore, system’s designers experience is very useful to achieve a correct IPs definition. Features are chosen only if they can be monitored: when a Feature is found, the range of values it can as-sume has to be provided. Maximum, average and minimum nominal values shall be gathered, along with the absolute maximum and minimum values that are the critical operational values of the system.  Impacting Factors are selected typically by experi-enced analysis of the system and scenario. Every as-pect that may modify the system behavior and its re-sponses may be an input of the system. In this context, IPs are suitable for the definition of a typical or maybe unexpected (but estimated) factors that can occur dur-ing the operations of the system in a given scenario. Theoretically, a feature doesn’t influence other pa-rameters of the system. If it would be found that a fea-ture has impact on other features, this will mean that it is an impacting factor. This aspect shows the flexibility of the methodology.  3.2 The influence functions definition  Once Features and Impacting Factors are gathered, it is still missed any kind of information about their rela-tionships. We can make hypothesis about the influence that every IP has on each F that may derive from the Figure 1. System Grey-Box Structure 14 IEEE EWDTS, Lviv, October 9-12, 2008designer experience and from other considerations. We resort to a simple mathematical representation of the relationship between the F and the IPs by meaning of an influence function, as follow:    Fi = Fi IP1,IP2,…,IPn( )  Each feature Fi  is expressed as a function of a subset of potential IPs. Each subset may be strictly connected with the scenario in which the system shall operate (environmental conditions, electrical factors, commu-nication issues etc...). These conditions may be hetero-genic so it is important to verify the feasibility of the validation under that particular condition. If that meas-urement is not feasible (for example because it is not possible to simulate the external orbital conditions of a system in a satellite) the IP shall be eliminated.  It can be easily noticed that the influence function is a n-dimensional function in its input space so it looks preferable identifying proper sub-spaces, or target pro-jections of interest. In other words, a target projection is an influence function in which a subset of IPs is taken as fixed value and only few remaining IPs are free. Thus, each projection will require a target meas-urement campaign, aimed at providing the required set of data. The identification of the target projections is made specifying the values the other IPs must assume. Tar-get projections must definitely concern, among the others, Features and Impacting Factors that impacted on the selection of the current Communication Channel as a potential candidate for space applications.  3.3 Measurement Campaigns  Target projections identified in previous, have to be planned for measurement campaigns by definition of Test Plans, in order to gather experimental data. A Test Plan is created specifying the range of values for each IP to be considered, the measure granularity and how to perform the measures. It has to be expressed in terms of:  • tools to be used;  • methodology to grab measures; • number of time the measure has to be re-peated.   Finally, the Test Plan requires also the Wall time and Manpower estimation. Now, for each target projection additional information is provided, since the test plan developed for the target projection contains all the details to perform the meas-urement campaign. Moreover, each target projection offers a view on a restricted portion of all possible as-pects of the relationship between IPs and Fs. Hence, resorting to projections and their test plan, the evalua-tion process is someway clustered.  After the measurement campaigns are done a result analysis can be performed then a proper evaluation function may be defined. At this step, a key point is the definition of the strategy to properly collect the ex-perimental data. The better the data is collected and organized the better it can be analyzed and used.  What is expected from the evaluation process is to de-rive a proper set of design requirements as a set of mandatory constrains to be followed when using the selected communication system in the field of interest and in the environments considered with respect to the IPs involved in each scenario. Furthermore, the evalua-tion gives the important advantage of easily derive a set of design guidelines, suggestions or recommenda-tions aiming at improving some feature of the selected Communication System.  4. Experimental Results  The presented methodology has been applied to three communication channels: MIL-STD 1553, 1-Wire and Profibus DP RS485 Data Buses. They need to be investigated to use in space and avionics applica-tions. MIL-STD-1553 describes a 1 Mb serial network [3]. It includes the definition of a physical layer and a mes-sage level protocol. Since its development in the 1970s, it is mainly used in legacy avionics, power, sen-sor and control systems [6]. There are two variants of 1553, the A version and the B version. The differences between the variants are minor but actually all systems should be using 1553B. Profibus DP is the most popular type of fieldbus with more than 14 million nodes (2006) in use worldwide [7]. In Europe it dominates with more than 60 % of the factory automation market. Profibus is designed for high-speed data exchange and only the Physical Layer and Data Link Layer are specified [4].  The 1-Wire technology uses a single wire (ground ref-erenced) to accomplish both communication and power transmission. Its peculiarities define the 1-Wire bus as a low cost communication channel, mainly used for sensors networks [5]. Following the first steps of the methodology, it was possible to build a complete list of functionalities of the data buses and to describe them in terms of features and impacting factors.  We were able to detect different classes of features after a deep analysis of the specifications, by applying a the system grey-box structure at the data bus opera-IEEE EWDTS, Lviv, October 9-12, 2008 15tions. Features were hierarchically classified, for con-venience, starting from a common, easy to understand, top-level domain (electrical features, communication features, dependability features and so on). For each class of features we identified the subsets of low-level features, as we were able to find them on the documen-tation. Obviously, we found that the more the data bus is used commercially, the more the description in terms of features is well done.  The impacting factors were identified during brain-storming sessions by considering all the possible vari-ables that may impact on the system. So, the satellite system designers can have a key role in defining IPs and collecting their significant values. The same way of features, it was possible to identify hierarchical classes of IPs that may impact on the functionalities and features of the data bus. In order to provide some example, these IPs include subsystem frequency, physical layout of the bus, network typologies, envi-ronmental conditions, fault tolerances and so on. For each class of IPs we identified the more specific factors derived from the constrains imposed by the satellite application. For example, the satellite environmental conditions can impact on the data bus in a satellite and they were identified in: operating temperature varia-tions, radiations, EMC, vibrations, humidity and so on.  Figure 2 provides an example of the structure for the 1553 Data Bus features. It exploits some of the Fea-tures in the Communication class (first level of the diagram). To simplify we have shown only a subset of the features gathered.  The hierarchical organization of features and impacting factors was used to interconnect the two structures as explained in Section 3.2. Resorting to influence func-tions (that we omit here for simplification) we connect the impacting factors to the feature they are suppose to influence to. Thus hierarchy simplifies the link infor-mation because the connection results to be hierarchi-cal too: if a feature at level n is connected to a set of IPs, all the children features inherit the connections to that set.      5. Conclusion and future work  In this paper we have presented a methodology for the evaluation of communication systems. The methodol-ogy provides a complete framework for the evaluation at all the abstraction levels. The modular structure of the methodology gives us the interesting chance to evaluate the system by measuring each class of feature separately and to experiment how the system reacts to the action of different IPs by keeping the IPs constant and only one variable.  Future work aims to apply complete measurement campaigns and to extend the methodology with a inno-vative results analysis strategy, in order to complete the evaluation process.  References  [1] K. Karlsson, H. Forsberg, “Emerging verification meth-ods for complex hardware in avionics”, 24th Digital Avionics Systems Conference, Vol. 1, 2005, pp. 61-12. [2] K.D. Shere, R.A. Carlson, “A methodology for design, test, and evaluation of real-time systems”, Computer, IEEE Computer Society Press, Volume 27, Issue 2, February 1994, pp. 35 – 48. [3] MIL-STD1553B, “Department of Defense Interface Standard For Digital Time Division Command/ResponseMultiplex Data Bus”, United States Department of Defense, pp. 1-10, Online Available: http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident_number=36973 [4] Acromag, “Introduction to Profibus DP,” Online Avail-able: http://www.acromag.com. [5] Maxim Application Note 1796, “Overview of 1-Wire Technology and Its Use”, December 2002, Online Available: http://www.maxim-ic.com/an1796. [6] Data Device Corporation (DDC), “BU-65569iX Hard-ware Manual MIL-STD 1553 BC/RT/MT PCI Interface Card”, Designer Guide, Online Available: http://www.ddc-web.com/Products/26/Default.aspx, January 2003, pp. 1-127.[7] Jingyu LIU, Yanjun FANG, Dahai ZHANG, “PROFIBUS-DP and HART Protocol Conversion and the Gateway Development”, 2nd IEEE Conference on Industrial Electronics and Applications, 2007, China, pp. 15-20. Figure 2. MIL - STD 1553 Features 16 IEEE EWDTS, Lviv, October 9-12, 2008                  Camera-ready was prepared in Kharkov National University of Radio Electronics  by Dr. Svetlana Chumachenko and Volodymyr Obrizan Lenin ave, 14, KNURE, Kharkov, 61166, Ukraine  Approved for publication: 20.09.2008. Format 60×841/8. Relative printer’s sheets:          . Circulation: 150 copies. Published by SPD FL Stepanov V.V. Ukraine, 61168, Kharkov, Ak. Pavlova st., 311   !"#$%!&' (')*+,%-)-  «./%0-1!/%0 2$+#3"-4!556 "! 7%!85+("-4!556 – 2008»  !3#" *%08+"+4&#5+ - 9!$3%4(:3+)- 5!;%+5!&:5+)- -5%4#$('"#"% $!0%+#&#3"$+5%3'  <#0!3"+$': .4%"&!5! =-)!>#53+ "! ?+&+0')'$ @A$%,!5 2$. B#5%5!, 14, 9CD<E, 9!$3%4, 61166, D3$!F5!  2%0*'(!5+ 0+ *-A&%3!;%F: 20.09.2008. G+$)!" 60×841/8. D)+4. 0$-3. !$3.       . H'$!I: 150 *$'). ?'0!5+: .27 GB ."#*!5+4 ?.?. ?-&. J3. 2!4&+4!, 311, 9!$3%4, 61168, D3$!F5!  444 IEEE EWDTS, Lviv, October 9-12, 2008

A Systematic Approach for Evaluating Satellite Communications Systems

PORTO Publications Open Repository TOrino

A Systematic Approach for 
Evaluating Satell ite Communica-
tions Systems
Authors: Di Carlo S., Prinetto P., Savino A., Tiotto G., Elia P.
Published in the Proceedings of the EEE 6th East-West Design & Test Symposium (EWDTS), 9-12 
Oct. 2008, Lviv, UA.
N.B. This is a copy of the ACCEPTED version of the manuscript. 
© 2000 IEEE. Personal use of this material is permitted. Permission from IEEE must be 
obtained for all other uses, in any current or future media, including reprinting/republishing 
this material for advertising or promotional purposes, creating new collective works, for resale 
or redistribution to servers or lists, or reuse of any copyrighted component of this work in 
other works.
!Politecnico di Torino
A Systematic Approach for Evaluating Satellite Communications Systems 
 
 
Stefano Di Carlo, Paolo Prinetto, Alessandro Savino, Gabriele Tiotto 
Politecnico di Torino, Dipartimento di Automatica e Informatica 
Email: {stefano.dicarlo, paolo.prinetto, alessandro.savino, gabriele.tiotto}@polito.it 
 
Paola Elia 
Thales Alenia Space 
Email: paola.elia@thalesaleniaspace.com 
  
 
Abstract 
 
The aerospace environment imposes straight opera-
tive conditions so every electronic system usually needs 
to be validated for these. The same way, communica-
tion systems need to be evaluated before their intro-
duction in aerospace applications. In the paper we 
present a new methodology for the evaluation of com-
munication systems in space applications. The meth-
odology aims, by abstraction, at identifying all the crit-
ical aspects for the evaluation and at defining a stand-
ard and reusable framework in order to be applicable 
to any Communication Systems. The methodology has 
been applied for the evaluation of three Data Bus for 
satellite communications: 1553, 1-Wire and Profibus 
DP RS 485 based systems have been analyzed and 
evaluated1. 
 
1. Introduction 
 
The high level of criticality and completeness de-
manded by industry in the aerospace field requires the 
identification of an evaluation methodology able to 
validate aerospace-designed systems with high accura-
cy, and to analyze those scenarios that may potentially 
impact their correct behavior. It is a matter of fact that 
the larger part of industry costs are represented by de-
velopment expenses in validation and testing [1]. 
Satellites make large use of electronic devices with 
strong requirements in terms of physical space con-
strains, and tolerance to radiations, vibrations, faults, 
and shock. In order to efficiently analyze potential 
sources of hazard in this type of systems, it is mandato-
                                                            
1 This work has been made in collaboration with Thales Alenia 
Space for the validation of communication channels to be used in a 
satellite. The target systems are described above in the paper. 
ry to identify all the electrical and environmental con-
ditions that may influence their behavior.  
While the influence of these environmental factors 
is not always deducible a-priori using a theoretical ap-
proach, it may be possible to provide proper tools al-
lowing to better understand the impact of a set of fac-
tors over the system, or a sub-part of it.  
Several studies propose different solutions for vali-
dating communication systems in satellites and avion-
ics, developing methods for the verification at different 
abstraction levels: from the electrical and physical lev-
el to the protocol level, [1] [2]. The main drawback of 
these solutions is that they are mainly application de-
pendent (e.g., terrestrial, avionics, space, etc.). Thus, 
the definition of an application independent methodol-
ogy allowing the evaluation of a communication sys-
tem at all abstraction levels, including the system level, 
is still a challenging problem.  
In this paper we propose a new methodology for the 
analysis and validation of communication systems. It is 
based on the abstract definition of critical aspects of 
the system and the identification of the potential im-
pact factors on them. The framework is studied to have 
modularity properties that are very useful whereas the 
evaluation will need different approaches.  Moreover, 
the abstract approach allows the methodology to be 
scenario independent.  
This paper is organized as follows: Section 2 over-
views the proposed methodology and a complete de-
scription of its abstraction level is provided. In Section 
3 the methodology is described, step by step, to show 
the entire workflow. Section 4 shows the experimental 
results when the methodology was applied for the vali-
dation of three commercially available communication 
channels, namely 1553 Data Bus, 1-Wire and Profibus 
Decentralized Periphery (DP) RS485, [3] [4] [5]. Sec-
tion 5 concludes the paper giving some future perspec-
tive of the methodology. 
 
2. Methodology Work Flow 
 
For validation purpose, a generic Communication 
System can be modeled as a grey box containing a set 
of Inputs and a set of Outputs (the System Grey-Box 
Structure in Figure 1). The Inputs represent the set of 
controlling factors, internal or external at the system 
that may in turn influence the system behavior, e.g. 
environmental temperature, power supply voltage, etc., 
whereas Outputs represent the set of characteristics that 
are controlled or influenced someway by the inputs (all 
or a subset of). The way in which they are controlled or 
influenced can be available or derived by different. 
Hereinafter, we will refer to inputs as Impacting 
Factors (IPs) and to outputs as Features (Fs), (Figure 
1). 
 
 
The goal of the proposed validation methodology is to 
provide users a medium to understand how different 
Impacting Factor may influence the System under 
evaluations in terms of influence of the considered 
features. The proposed methodology is composed of 
several sequential steps, as follows: 
 
1. Selecting the target Communication System. 
The communication system has to be properly 
defined in terms of standard, used devices, 
etc.; 
2. Gathering all the Features. Features are ex-
tracted by analyzing the system and by care-
fully defining the aspects of the system that 
need to be validated. They can be clustered in 
classes that do not depend on a particular 
communication channel; 
3. Identifying all the Impacting Factors. Using 
system designers experience and the system 
documentation (like the communication chan-
nel standard, the target application, etc.) the 
Impacting Factors are identified; 
4. Defining how each Feature may be influenced 
by IPs. Each feature F is investigated to define 
how it is influenced by a subset of IPs; 
5. Defining how Impacting Factors and Features 
shall be evaluated. Practical considerations on 
how the measurement campaigns have to be 
performed are made in order to obtain a scien-
tific and structured way of work; 
6. Performing the Measurement Campaigns. 
Once the campaigns are defined, they are 
made and all data is collected for the further 
evaluations. 
 
3.  Methodology Description 
 
In this section we exploit the methodology, step by 
step, in order to show how it was design for. We focus 
on terminology definitions and abstraction strategies. 
 
3.1 Features and Impacting Factors identifica-
tion 
 
The identification of Features and Impacting Factors, 
as described above, requires a deep analysis of the tar-
get system and scenario. Resorting to the system gray-
box structure, the analysis has to be performed by 
gathering all the possible characterizations and con-
strains from channel specifications, designer guidelines 
and data sheets. The IPs are mainly derived from con-
siderations strictly connected with the operative condi-
tions. Furthermore, system’s designers experience is 
very useful to achieve a correct IPs definition. 
Features are chosen only if they can be monitored: 
when a Feature is found, the range of values it can as-
sume has to be provided. Maximum, average and min-
imum nominal values shall be gathered, along with the 
absolute maximum and minimum values that are the 
critical operational values of the system.  
Impacting Factors are selected typically by experi-
enced analysis of the system and scenario. Every as-
pect that may modify the system behavior and its re-
sponses may be an input of the system. In this context, 
IPs are suitable for the definition of a typical or maybe 
unexpected (but estimated) factors that can occur dur-
ing the operations of the system in a given scenario. 
Theoretically, a feature doesn’t influence other pa-
rameters of the system. If it would be found that a fea-
ture has impact on other features, this will mean that it 
is an impacting factor. This aspect shows the flexibility 
of the methodology. 
 
3.2 The influence functions definition 
 
Once Features and Impacting Factors are gathered, it is 
still missed any kind of information about their rela-
tionships. We can make hypothesis about the influence 
that every IP has on each F that may derive from the 
Figure 1. System Grey-Box Structure 
designer experience and from other considerations. We 
resort to a simple mathematical representation of the 
relationship between the F and the IPs by meaning of 
an influence function, as follow: 
 
  
€ 
Fi = Fi IP1,IP2,…,IPn( ) 
 
Each feature 
€ 
Fi  is expressed as a function of a subset 
of potential IPs. Each subset may be strictly connected 
with the scenario in which the system shall operate 
(environmental conditions, electrical factors, commu-
nication issues etc...). These conditions may be hetero-
genic so it is important to verify the feasibility of the 
validation under that particular condition. If that meas-
urement is not feasible (for example because it is not 
possible to simulate the external orbital conditions of a 
system in a satellite) the IP shall be eliminated.  
It can be easily noticed that the influence function is a 
n-dimensional function in its input space so it looks 
preferable identifying proper sub-spaces, or target pro-
jections of interest. In other words, a target projection 
is an influence function in which a subset of IPs is tak-
en as fixed value and only few remaining IPs are free. 
Thus, each projection will require a target measure-
ment campaign, aimed at providing the required set of 
data. 
The identification of the target projections is made 
specifying the values the other IPs must assume. Tar-
get projections must definitely concern, among the 
others, Features and Impacting Factors that impacted 
on the selection of the current Communication Channel 
as a potential candidate for space applications. 
 
3.3 Measurement Campaigns 
 
Target projections identified in previous, have to be 
planned for measurement campaigns by definition of 
Test Plans, in order to gather experimental data. A Test 
Plan is created specifying the range of values for each 
IP to be considered, the measure granularity and how 
to perform the measures. It has to be expressed in 
terms of: 
 
• tools to be used;  
• methodology to grab measures; 
• number of time the measure has to be repeat-
ed.  
 
Finally, the Test Plan requires also the Wall time and 
Manpower estimation. 
Now, for each target projection additional information 
is provided, since the test plan developed for the target 
projection contains all the details to perform the meas-
urement campaign. Moreover, each target projection 
offers a view on a restricted portion of all possible as-
pects of the relationship between IPs and Fs. Hence, 
resorting to projections and their test plan, the evalua-
tion process is someway clustered.  
After the measurement campaigns are done a result 
analysis can be performed then a proper evaluation 
function may be defined. At this step, a key point is the 
definition of the strategy to properly collect the exper-
imental data. The better the data is collected and orga-
nized the better it can be analyzed and used.  
What is expected from the evaluation process is to de-
rive a proper set of design requirements as a set of 
mandatory constrains to be followed when using the 
selected communication system in the field of interest 
and in the environments considered with respect to the 
IPs involved in each scenario. Furthermore, the evalua-
tion gives the important advantage of easily derive a 
set of design guidelines, suggestions or recommenda-
tions aiming at improving some feature of the selected 
Communication System. 
 
4. Experimental Results 
 
The presented methodology has been applied to 
three communication channels: MIL-STD 1553, 1-
Wire and Profibus DP RS485 Data Buses. They need 
to be investigated to use in space and avionics applica-
tions. 
MIL-STD-1553 describes a 1 Mb serial network [3]. It 
includes the definition of a physical layer and a mes-
sage level protocol. Since its development in the 
1970s, it is mainly used in legacy avionics, power, sen-
sor and control systems [6]. There are two variants of 
1553, the A version and the B version. The differences 
between the variants are minor but actually all systems 
should be using 1553B. 
Profibus DP is the most popular type of fieldbus with 
more than 14 million nodes (2006) in use worldwide 
[7]. In Europe it dominates with more than 60 % of the 
factory automation market. Profibus is designed for 
high-speed data exchange and only the Physical Layer 
and Data Link Layer are specified [4].  
The 1-Wire technology uses a single wire (ground ref-
erenced) to accomplish both communication and power 
transmission. Its peculiarities define the 1-Wire bus as 
a low cost communication channel, mainly used for 
sensors networks [5]. 
Following the first steps of the methodology, it was 
possible to build a complete list of functionalities of 
the data buses and to describe them in terms of features 
and impacting factors.  
We were able to detect different classes of features 
after a deep analysis of the specifications, by applying 
a the system grey-box structure at the data bus opera-
tions. Features were hierarchically classified, for con-
venience, starting from a common, easy to understand, 
top-level domain (electrical features, communication 
features, dependability features and so on). For each 
class of features we identified the subsets of low-level 
features, as we were able to find them on the documen-
tation. Obviously, we found that the more the data bus 
is used commercially, the more the description in terms 
of features is well done.  
The impacting factors were identified during brain-
storming sessions by considering all the possible vari-
ables that may impact on the system. So, the satellite 
system designers can have a key role in defining IPs 
and collecting their significant values. The same way 
of features, it was possible to identify hierarchical clas-
ses of IPs that may impact on the functionalities and 
features of the data bus. In order to provide some ex-
ample, these IPs include subsystem frequency, physical 
layout of the bus, network typologies, environmental 
conditions, fault tolerances and so on. For each class of 
IPs we identified the more specific factors derived 
from the constrains imposed by the satellite applica-
tion. For example, the satellite environmental condi-
tions can impact on the data bus in a satellite and they 
were identified in: operating temperature variations, 
radiations, EMC, vibrations, humidity and so on.  
Figure 2 provides an example of the structure for the 
1553 Data Bus features. It exploits some of the Fea-
tures in the Communication class (first level of the 
diagram). To simplify we have shown only a subset of 
the features gathered.  
The hierarchical organization of features and impacting 
factors was used to interconnect the two structures as 
explained in Section 3.2. Resorting to influence func-
tions (that we omit here for simplification) we connect 
the impacting factors to the feature they are suppose to 
influence to. Thus hierarchy simplifies the link infor-
mation because the connection results to be hierar-
chical too: if a feature at level n is connected to a set of 
IPs, all the children features inherit the connections to 
that set.     
 
5. Conclusion and future work 
 
In this paper we have presented a methodology for the 
evaluation of communication systems. The methodolo-
gy provides a complete framework for the evaluation at 
all the abstraction levels. The modular structure of the 
methodology gives us the interesting chance to evalu-
ate the system by measuring each class of feature sepa-
rately and to experiment how the system reacts to the 
action of different IPs by keeping the IPs constant and 
only one variable.  
Future work aims to apply complete measurement 
campaigns and to extend the methodology with a inno-
vative results analysis strategy, in order to complete the 
evaluation process. 
 
References 
 
[1] K. Karlsson, H. Forsberg, “Emerging verification meth-
ods for complex hardware in avionics”, 24th Digital Avionics 
Systems Conference, Vol. 1, 2005, pp. 61-12. 
 
[2] K.D. Shere, R.A. Carlson, “A methodology for design, 
test, and evaluation of real-time systems”, Computer, IEEE 
Computer Society Press, Volume 27, Issue 2, February 1994, 
pp. 35 – 48. 
[3] MIL-STD1553B, “Department of Defense Interface 
Standard For Digital Time Division Command/Response 
Multiplex Data Bus”, United States Department of Defense, 
pp. 1-10, Online Available: 
http://assist.daps.dla.mil/quicksearch/basic_profile.cfm?ident
_number=36973 
[4] Acromag, “Introduction to Profibus DP,” Online Availa-
ble: http://www.acromag.com. 
[5] Maxim Application Note 1796, “Overview of 1-Wire 
Technology and Its Use”, December 2002, Online Available: 
http://www.maxim-ic.com/an1796. 
Figure 2. MIL-STD 1553 Features 
[6] Data Device Corporation (DDC), “BU-65569iX Hard-
ware Manual MIL-STD 1553 BC/RT/MT PCI Interface 
Card”, Designer Guide, Online Available: http://www.ddc-
web.com/Products/26/Default.aspx, January 2003, pp. 1-127. 
[7] Jingyu LIU, Yanjun FANG, Dahai ZHANG, 
“PROFIBUS-DP and HART Protocol Conversion and the 
Gateway Development”, 2nd IEEE Conference on Industrial 
Electronics and Applications, 2007, China, pp. 15-20. 
 
 


A methodology for design, test, and evaluation of real-time systems”,

Application Note 1796, “Overview of 1-Wire Technology and Its Use”,

Emerging verification methods for complex hardware in avionics”,

https://iris.polito.it/retrieve/handle/11583/1844479/50135/2008-EWDTS-Satellite.pdf

A Systematic Approach for Evaluating Satellite Communications Systems

Abstract

Similar works

Full text

Available Versions

PORTO@iris (Publications Open Repository TOrino - Politecnico di Torino)

PORTO Publications Open Repository TOrino