NASA Technical M_emorandum 105274 .....

AIAA-91-3423

:::._ Evaluation of C0mp0nents,_Sub@stems; ...........and NetWorks for High Rate, HighFrequency Space CommuniCations

Robert L Kerczewski, William DI Ivancic, ...... _ :_ - ......

and John E. Zuzek

Lewis Research Center

Cleveland. Ohio .... ....... -

, ..... Prepared for the "

Conference on Advanced Space Exploration Initiative TechnoJ0giescosponsored by AIAA, NASA.OAI -

Cleveland, Ohio, September 4-6, !99i _ -- . ....

N/ A÷

(NASA-T_4- I052 74)

SUBSYSTEMS, ANUF REQUEf'iC Y SPACE

EVALUATION OF COMPONENTSf

NETWORKS FUR HICH RATF, HIGH

COMMUNICATIONS (NASA) 13 p

CSCL 17B

N92-12151

G3/32

UnCldS

0048225

https://ntrs.nasa.gov/search.jsp?R=19920002933 2018-06-14T20:40:09+00:00Z

w _ k --

EVALUATION OF COMPONENTS, SUBSYSTEMS, AND NETWORKSFOR HIGH RATE, HIGH FREQUENCY SPACE COMMUNICATIONS

Robert J. Kerczewski', William D. Ivancic, and John E. Zuzek"NASA Lewis Research Center

Cleveland, Ohio

Abstract

The development of new space communicationstechnologies by NASA has included both commercialapplications and space science requirements. AtNASA's Lewis Research Center, methods and facilities

have been developed for evaluating these newtechnologies in the laboratory. NASA's SystemsIntegration, Test and Evaluation (SITE) SpaceCommunication System Simulator is a hardware-basedlaboratory simulator for evaluating spacecommunications technologies at the component,subsystem, system, and network level, geared toward

high frequency, high data rate systems. The SITEfacility is wen-suited for evaluation of the newtechnologies required for the Space ExplorationInitiative (SEI) and advanced commercial systems. Thispaper describes the technology developments and

evaluation requirements for current and plannedcommercial and space sdence programs. Also examinedare the capabilities of SITE, the past, present, andplanned future configurations of the SITE facility, andapplications of SITE to evaluation of SEI technology.

antenna technology, on-board switching and processing,high rate bandwidth-efficient modulation and coding,microwave, millimeter-wave, and optical intersatellitelinks (ISL), cost-efficient ground terminals, and networkimplementation and control.

At NASA's Lewis Research Center, we are concerned

with methods for evaluating these new technologies inthe laboratory as they are developed, and performingsimulation in hardware at the network and system levelin order to both evaluate and extend the development ofsystems and subsystems.

In the following sections, some of NASA's current andplanned future commercial and space science technologyevaluation requirements will be described. Thedevelopment of the SITE Space Communication SystemSimulator will be reviewed, including current projects

and future plans which include MMIC evaluation,intersatellite link networking, and on-board switchingand processing. Application of the SITE facilities andevaluation techniques to advanced SEI communicationsystem technologies will be discussed.

Introduction Space Communication Technology Trends

To enable various potential future commercial services,and to meet NASA's space science communicationneeds such as future TDRSS-type data relay and SEIcommunication systems, numerous technologydevelopment programs exist or are planned. Thesetechnologies include Ka-Band and millimeter-wavefrequency transmit and receive hardware, multi-beam

In commercial communications systems, Lewis ResearchCenter has been involved in the development of theAdvanced Communications Technology Satellite(ACTS), a Ka-Band multi-beam satellite system which

_mcludes on-board IF and baseband switching and

processing as the heart of a time division multiple access(TDMA) network. This work is now being followed

* Member, AIAA

Copyright © 1991 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title

17, U.S. Code. The U. S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Government

pu_. All other rights are reserved by the copyright owner.

other by advanced commercial concepts, such asFDMA-TDMA systems including advanced on-boardswitching and processing, MMIC-based satellitehardware, low-cost ground terminal development, andimproved modulation and coding.

These systems require the development of advancedcomponents and subsystems. Medium and high poweramplifiers at frequencies up to 30 GHz are needed forboth space and ground applications, using electron tube('INCT) and solid state technology. Higher efficiencyand reliability is the goal for the space-based segment,while low cost is the primary driver in ground terminalhardware. Low noise receivers also fit these generalrequirements.

Components for IF switching and subsystems forbaseband switching and processing are also currently indevelopment. For IF switching, as well as receiver andother analog processing functions, monolithic microwaveintegrated circuit (MMIC) technology is being applied.Digital signal processing techniques, high speedelectronic circuits, and optical processing are beingdeveloped for digital beamforming and on-boarddemodulation/remodulation functions. The

development of advanced modems and codecs, especiallyat higher data rates (> 200 Mbps) is being driven by theneed to transfer large volumes of data in short periodsof time over limited access systems such as medical,scientific, and supercomputer networks.

Other subsystems which must be developed and verifiedinclude the ground terminal, which can be subdividedinto transmit and receive sides as well as RF and digitalportions. Evaluation of transmit, receive, andIF/baseband processing portions of the satellitetransponders is also necessary.

As satellite systems are required to perform more andmore switching and processing tasks, the role of networkcontrol increases in importance. It is necessary to testthe network's response in initial acquisition and tracking,controlling entrance and exit of users to the system, :;controlling and monitoring the satellite processinghardware, and responding to system perturbations suchas interference, rain fade, and satellite range variations.

The complexity and evolutionary aspects of the potentialSpace Exploration Initiative program offer a tremendousnumber of technological challenges in the areas of

Figure I - Space Exploration Initiative Communication System Concept

telecommunicationsand information management. The

SEI system may eventually include lunar and Marssurface terminals, a variety of science instruments,astronauts, rovers, robotic elements, and in-orbitfacilities such as piloted vehicles and lunar and Marsrelay satellites I as exemplified by Figure 1. Many ofthese nodes will be linked with high data rate long rangelinks which will require an evolution from Ka-bandfrequencies to millimeter-wave frequencies and possiblyto optical transmissions for certain links. Relay satelliteswill need to squeeze every conceivable dB out of thelinks requiting advances in efficiencies and designs formany technologies. As the network evolves, itscomplexity, connectivities, and technologies must alsoevolve.

One key technolog3, will be very low noise (1.0 - 1.5 dBor less) space-based receivers. These demands maysuggest constraints on various receiver subsystemcomponents as well. Another key subsystem will be thespace-based antennas. It is likely that phased arrayantennas probably based on MMIC technologies will berequired for some communications nodes. In addition,frequencies of Ka-band and higher will place newdemands on the antenna subsystems and feed networkcomponents. Additional efficiendes might be found inthe integration of optical technologies such as opticalinterconnects or beam forming networks into theantenna system. Very low loss feed systems will berequired in many cases.

Beam switching will also be required with technologiessimilar to or possibly beyond ACTS. Anotherimplication of this switching would be a basebandprocessor and/or microwave switch matrix for routingsignals. Other components such as amplifiers, bothelectron beam (TWTA) and solid state (SSPA), wouldneed to be tested and evaluated, especially those withadvances in efficiency or power and those designed tooperate at millimeter-wave frequencies. Anotherpossibility for development and testlng-would bemodems and coders. Modems may have specialrequirements in that different SEI links may requiredifferent modulation schemes since some links will be

bandwidth-limlted while others, such as the Mars returnlinks, will be severely power-limited. This translates tothe use of OPSK or some other M-ary PSK scheme formost links and the use of some high order FSKmodulation scheme or advanced trellis-coded

modulation for the Mars return links. Cross-strappingbetween these two networks may cause additionaldifficulties. Also, the SEI communications links would

likely place tremendous demands on the errordetecting/correcting capabilities of the subsystemscompared to conventional Earth orbiting systems. Awide range of requirements are likely with bit errorrates from 10-3 for voice to as low as 10"12 for essential

telemetry or science data. The latter requirement maybe necessitated by any sort of data compression schemewhich require more stringent error control. Finally,various data compression algorithms will be utilized andthe hardware for these will need to be integrated andtested in the subsystems and systems in which they willoperate.

The demands the SEI missions will place on thetelecommunications and information managementnetworks will be similar to those imposed on an Earth-based communications network except that the resourcesmust be managed in space. It is likely that the systemwill evolve into a complex network which must be ableto allocate channels and communications resources on

demand or even autonomously. Thus, some sort ofminimally attended network management systemincluding an artificial intelligence based networkplanner/scheduler may be needed to deal with theseresources. Additionally, network and component faulttolerance will be of paramount importance in thesemissions. The networks themselves will have to be able

to detect and isolate faults and repair them or workaround them as is necessary.

Link impairments and the systems responses to themwill have to be modelled and evaluated. Such

impairments will include atmospheric attenuation,pointing errors due to strict antenna pointing accuracies,network and component outages, and occultations orother unforeseen anomalies. It will also be necessary totest various communications protocols for the datasystems and potentially integrate space-based processorsand data storage devices into the total system.

T¢¢hnglggy Evaluation Approach

The communications technologies must be evaluated atfour levels: component, subsystem, system, and thenetwork level.

The dividing line between components and subsystemsis somewhat arbitrary. Thus, they have similar testrequirements. Important information regarding theelectrical performance can be gained through bench-top

3

testing of stand-alone hardware. However, placing thecomponent in a system environment and using bothunmodulated and modulated test signals givesconsiderable information on the componenrs orsubsystem's performance in transmitting real signals, aswell as its effect on the overall system. The effect of acomponent or subsystem on the bit-error rate (BER) ofthe system can be measured and compared with othercomponents, different designs, varying operatingconditions, or with the component or subsystembypassed. The effect of a component or subsystem onthe operation of the network can only be measured byplacing it in a portion of a network containing at leastthe minimum number of nodes required for an accuratenetwork model.

Some components or subsystems require other portionsof the system for proper evaluation. Components suchas codecs require modems for performancemeasurement, and the modems require noise and signalvariation and calibration as well as BER measurement

systems, all of which can be made part of the overallsystem test environment. The switching subsystem foran on-board processing satellite requires a number oftest signals which must resemble the real signals in thesystem. In addition, interfaces between these majorsubsystems and between the system and users requireevaluation and verification. Such evaluation can only beperformed in an end-to-end system environment.

Evaluation of systems must include the end-to-endperformance of the system under all possible operatingconditions. However, the testing must also take into

account perturbations and distortions occurring over theentire communications link. Amplitude and phasedistortions, whether induced by hardware or atmosphericpropagation effects, noise, interference, and satellite

range variation can affect system and networkperformance. The investigation and quantification ofthese effects and the methods developed to counteractthem are of great interest. The test system can bedesigned to introduce these distortions and measuretheir effects.

Network control software and interfaces, switching,processing, and traffic handling algorithms, and overallsystem control methods can be developed and verifiedby simulating a minimum portion of a network inhardware. For a multi-beam sateUite-switched TDMA

(SS-TDMA) type system, for example, a minimum ofthree ground terminals located in three separate antennaspot beams is required. The development of such asimulator also allows a complete evaluation of theground terminals to take place, since ground terminalacquisition, synchronization, tracking, and data transferfunctions are heavily dependent on the network.

All of these requirements point to the need for a systemand network oriented approach to spacecommunications technology evaluation. Although theneed for initial functional testing of components viastandard bench top testing remains, nearly all of theother electrical performance testing requirements ateach of the four technology levels can be met with anintegrated test facility. In the next section, such afacility currently in use at NASA Lewis is described.

275-30.0G_

Single Channel Ka Band

Wldeband Transponder

EXPEPJMENT I

CONTROL

AND MONITOR

COMPUTER

17.7-20_.

Figure 2 - SITE Space Communication System Simulator - Phase I

The SITE Space Communication System Simulator

As mentioned above, the four technology levels can beevaluated in a single laboratory facility which includesthe minimum amount of hardware required for assessing

network operations combined with built-in monitoring,measurement, system control and experiment stimulationcapabilities. The SITE evaluation facility includes all ofthese functions, under computer control and has beenused for evaluation of component, subsystem, system,and network technologies. In the initial configuration ofthe SITE facility, a single bent-pipe 30/20 GHz highdata rate satellite link was created. Further expansion

and development in the past several years have lead toa three-terminal network simulation, with completehardware links and multi-rate digital ground terminals.Plans are now being developed for the next phase ofexpansion, which will allow the evaluation of on-boardswitching and processing technologies currently underdevelopment, intersatellite link hardware and networks,and other satellite and ground terminal hardware and

subsystems.

Initial Configuration of SITE

The SITE Space Communication System Simulator wasoriginally conceived in 1982 as a means of evaluating

proof-of-concept components being developed forNASA'sAdvanced Communications Technology Satellite(ACTS) project 2. The initial Phase I system consistedof a single 220 Mbps satellite channel, operating at 30GHz uplink and 20 GHz downlink frequencies, shown in

Figure 2. The system was able to measure bit-error rate

(BER) as a function of F._/N o using a continuous 220Mbps MSK-modulated data stream.

The SITE Phase I system was used to evaluate Ka-Bandcomponents including solid state and TWT poweramplifiers, low noise receivers, and matrix switches 3"6.The performance of the _tellite 30/20 GHz transponderwas evaluated 7, as well as the effects of variable

transponder output power for rain attenuationcompensation s, amplitude variations and equalization 9,and group delay distortion 1°.

Although the Phase I system contained power,frequency, spectrum, and configuration monitoring, themost useful feature was the ability to automatically

measure complete BER curves as a function of E.o/N o.This was accomplished through the use of computersoftware and RF and digital hardware which allowed a

pseudorandom data sequence to be generated,modulated, transmitted through the system under test,demodulated, and compared to a replica of the originaldata for error detection. Controlled amounts of noise

are added and the Et,/N o is measured and incrementedin 1 dB steps 11"13.

SITE M_llti-Terminal Network Simulation

Without eliminating the capabilities of the Phase Isystem, the SITE facility has been expanded in Phase IIof the project to a three-terminal TDMA network,shown in Figure 3. This network includes three groundterminals, a three channel satellite transponder, sevensimulated users, audio and video transmission, aradiative link to a remote terminal, and full network

control capabilities.

The ground terminals currently allow continuoustransmission at 220 Mbps or bursted transmission atrates of 1 to 200 Mbps. Each ground terminal containsits own BER measurement and E.JN o calibration, andthus can measure BER performance through anytransponder path. As Figure 3 shows, the satellitematrix switch allows interconnectivity of any two groundterminals. Two ground terminals are equipped withthree simulated users 14, one of which interfaces to audioand video data. The third ground terminal, which canbe located either in the third beam (third channel) or atthe remote terminal, has a flexible user interface

allowing numerous users at various rates.

Satellite range variation simulation is provided to allowa realistic timing environment for a TDMA system ts.Satellite range and doppler shift affect the ability of

ground terminals to synchronize with the network, andthus any system or network with dynamic switching musthave this simulation capability.

For Ka-band systems, rain attenuation on both uplinkand downlink portions is a primary concern. To allow

evaluation of the effects on system performance, and oncompensation techniques, methods for simulatingrealistic rain events have been included in the SITE

facility 16.

A remotely located ground terminal accessed through aradiative 30/20 GHz link is also a part of the currentSITE facility 17. This terminal will demonstrate networkcontrol of a remote terminal, and will eventually be usedto demonstrate a remote control and observation of

5

u

6

space science experiments, as might occur at the spacestation or in SEI activities.

The primary project currently underway for this PhaseII system is a TDMA network simulation andevaluation 18. In this program, the performance of asatellite matrix switched TDMA network will be

evaluated. The three-channel transponder allows a 3 X3 network to be evaluated. This is the minimum

number of network nodes required for a goodsimulation. The Master Control Terminal (MCT) mustfirst acquire and track the satellite under varyingsatellite range, E,o/qqo, fading and interferenceconditions. The network control must then bring atraffic terminal into the network with completesynchronization under these conditions. Finally, thenetwork must demonstrate the ability to bring in asecond traffic terminal and have it communicate with

the first traffic terminal, independently of the MCT.

By using the remote terminal, another set ofexperiments can be performed in which two trafficterminals located within the same spot beam can bebrought into the network. The remote terminal can alsolocated in an adjacent frequency channel for interferenceexperiments.

For all aspects of the network simulation, varyingcombinations of satellite range delay variation, rainattenuation, noise, interference, and signal distortionscan be introduced. These experiments, to be carried onfor the next two years, are being accomplishedconcurrently with other component testbed type uses ofthe facility. Performance measurements for groundterminal hardware, simulation of the ACTS transpondercharacteristics, and experiments with advanced modemsand codecs are planned.

Future Develot_ment of the SITE Facility_

The development of a generic test ground terminal willbe undertaken within the next year. This groundterminal will idlow a variety of modulation formats,coding schemes, and data rates to be interfaced with theSITE facility. Using the same BER measurement andE.b/N o calibration methods as are used currently, severalnew capabilities will be developed. A comparison ofmodulation formats and coding schemes as applied tosatellite networks as well as the performance of thesystem at various rates, bandwidths, modulations andcodings will be possible. The performance of individualcomponents under these conditions can be evaluated.

Finally,the performance of the modems and codecsthemselves, in the presence of noise, interference, andnonlinearity will be measured.

In the course of the SITE facility development,especially in the last few years, the demand forcomponent testing and system-level evaluation andexperimentation outside of the planned SITE networksimulation has increased. In addition, new uses for thefacility and new experiment concepts have beendeveloped by the SITE staff. These demands, and adesire to demonstrate the uses of in-house technologydevelopments, has led to the planning of a secondsatellite transponder to be used in conjunction with thecurrent hardware. This second transponder will bebased on MMIC-based Ka-band hardware

developments, and will also be designed to handlehigher frequency components and data links in the

future. In addition to handling the increasing test andexperiment load, the second transponder will have twomajor uses.

The first use involves the demonstration and evaluation

of on-board switching and processing technologycurrently being developed in-house and under contractat NASA Lewis. This technology development is drivenby the need to develop systems with low cost groundterminals for low data rate users. This can be

accomplished through narrowband FDMA upllnk accessarchitectures which eliminate the need for a high poweruplink transmitter. TDMA dowulinks can operate in awideband mode, with the spacecraft transmitterproviding adequate power to allow small apertureground terminals.

In the systems being developed by NASA, the uplinknarrowband FDMA traffic, resulting from severalspatially isolated uplink beams, will be demodulated bymultichannel demultiplexer demodulators (MCDD), onefor each uplink beam. The demodulated uplink userdata will be switched and routed to proper one ofseveral downlink beam by the information switchingprocessor (ISP). Downlink traffic will be transmittedusing high rate modulation in a TDMA format, allowingthe satellite high power transmitter to operate atmaximum power, thus improving downlink slgnal-to-noise ratio.

The on-board processing portion such a system is shownin Figure 4. The second transponder will be designed toaccommodate the FDMA/TDMA architecture andprocessing equipment as well as the TDMApI'DMA

7

FDMARt_t_[7

_HR_qlZ INQ

BUFFER

__ Ir_ I TCI-¢- TO- T DM tFOR_IATTER

TDM

Figure 4 - On-board Processing Portion for FDMA/TDMA Satellite System

architectures. The performance of the system can beassessed in terms of the noise, interference, non-

linearity, rain fade, and satellite range variationparameters, as well as other parameters unique to theFDMA/TDMA architecture, such as intermodulation,adjacent channel interference, and amplitude variationbetween FDM channels.

The other major use of the second transponder will beas part of an intersatellite link networking simulation.Although still in the conceptual stage, the intersatellitelink simulation will allow the investigation of networkingconcepts for both commercial and space scienceapplications, and the evaluation of components andsubsystems designed for such applications. It will allowthe current SITE capabilities to remain intact, and willadd features unique to intersatellite data relay systems.A conceptual model of the future SITE facility is shownin Figure 5. Given the intended design of the secondtransponder to allow dual architectures, the networkingand interfacing aspects of linking similar as well asdissimilar networks will be examined. The timetable for

implementation of these concepts will be driven by thefunding availability in the next several years.

Applications to SEI Technolo_es

The technology evaluation methods applied in the SITEproject to commercial systems are well-suited forapplication to the long-term development of an SEIcommunication network. Low noise receivers, TWT andsolid state power amplifiers, and microwave switches inthe Ka-band region can be evaluated in the currentSITE facility. Those which may be developed in otherfrequency bands can be evaluated with slightmodifications to the current facility or in the secondtransponder. Modems and codecs, data compressionhardware, and baseband processing subsystems can alsobe evaluated in the current version of the facility.

As hardware technology developments becomecomplete, the development method followed for thecurrent SITE simulator can be used to gradually evolvea more and more complex laboratory simulation systemdesigned for the SEI mission. The system would beginwith individual link simulators designed to test specificportions of the overall SEI network. Adding othersystem portions, transponders, intersatellite links andground stations, a network simulation facility will bedeveloped which will allow complete testing of network

IIn-o _1

o

0

!

9

functions, individual systems and subsystems, andcomponents in the presence of complete networkcontrol, and system and link impairments. In operatingsuch a network, the delays, delay variations and dopplershifts ultimately become quite large, and systemsynchronization must be tested with these impairments

properly simulated. Finally, the unattended networkcontrol architectures, which will be an ongoing paralleldevelopment, can be applied to a realistic network forfull evaluation and verification.

Ultimately, by combining the hardware and subsystemswhich will need to be developed individually for the SEImission, a highly versatile laboratory simulation system,capable of evaluating technologies at the component,subsystem, system, and network level can be developedat a minimum cost. The long-term nature of the SEImission assures a gradual evolution and expansion of theSEI communication network. Thus, a simulation facilitydeveloped in an evolutionary fashion as suggested herewill contribute significantly the long-term success of theSEI mission.

Summary

We have described some of the major development andevaluation requirements for commercial and space

science and exploration communications systems of thefuture. The methods employed for evaluation on thecomponent, subsystem, system, and network level havebeen described. The SITE Space CommunicationsSystem Simulator is a test system that has been designedto meet these evaluation requirements, especially forhigh frequency and high data rate systems. The SITESystem has produced significant results in the evaluationand development of components, subsystems, andnetworks. Constant revision and enhancement of the

system is continuing in order to keep pace withexpanding technology evaluation requirements. The SEImission, with its challenging complexity and developmentrequirements, is well-suited for the technologyevaluation approach developed in the SITE simulationfacility.

REFERENCES

1 Ponchak, D. S., Zuzek, J. E., Whytc, W. A. Jr.,Spence, R. L., and Sohn, P. Y., "A TechnologyAssessment of Alternative Communications

Systems for the Space Exploration Initiative',

2

4

10

13th AIAA Communication Satellite Systems

Conference, March, 1990 (NASA TM 103243).

BagweU, J. W., "A System for the Simulationand Evaluation of Satellite Communication

Networks', 10th AIAA Communication SatelliteSystems Conference, March, 1984 (NASA TM83531).

Wald, L. W., "Characterization of a 30 GHz

IMPATr Solid State Amplifier', NASATechnical Memorandum 100876, July, 1988.

Shalkhauser, K. A., and Fujikawa, G., "Bit-Error Rate Testing of High Power 30 GHzTraveling Wave Tube for Ground TerminalApplications', NASA Technical Paper 2365,October, 1986.

Kerczewski, R. J., "The Bit-Error RatePerformance of a Satellite Microwave Matrix

Switch', 12th A/AA Communication SatelliteSystems Conference, March, 1988 (NASA TM100285).

Kerczewski, R. J., Ponchak, G. E., andRomanofsky, R. R., "Performance of Five 30GHz Satellite Receivers', 1989 IEEE MTr

International Microwave Symposium', June,1989 (NASA TM 101960).

Kerczewsld, R. J., and Fujikawa, G.,"Performance Measurements for a Laboratory-Simulated 30/20 GHz Communication SatelliteTransponder', 13th AIAA InternationalCommunication Satellite Systems Conference,March, 1990 (NASA TM 102424).

Fujikawa, G., and Kerczewski, R. J.,"Performance of a Ka-Band Satellite SystemUnder Variable Signal Power Conditions', 1987IEEE MTT International Microwave

Symposium, June, 1987 (NASA TM 88984).

Kerczewsld, R. J., Fujikawa, G., Svoboda, J. S.,and Lizanich, P. J., "Effects of AmplitudeDistortion and IF Equalization on SatelliteCommunication System Bit-Error RatePerformance', 13th AIAA CommunicationSatellite Systems Conference, March, 1990.(NASA TM 102415).

10 Kerczewski, R. 3., "A Study of the Effect ofGroup Delay Distortion on an SMSK SatelliteCommunication Channel', NASA TechnicalMemorandum 89835, April, 1987.

11 Windmiller, M. J., "Unique Bit-Error RateMeasurement System for SatelliteCommunications Systems', NASA TechnicalPaper 2699, March, 1987.

12 Kerc.zewsld, R. J., Daugherty, E. S., andKramarchuk, I., "Automated Measurement ofthe Bit-Error Rate as a Function of Signal-to-Noise Ratio for Microwave Communication

Systems', 29th Automatic RF TechniquesConference, June, 1987 (NASA TM 89898).

13 Shalkhauser, M. J., and Budinger, J. M.,"Digitally Modulated Bit-Error RateMeasurement System for MicrowaveComponent Evaluation', NASA TechnicalPaper 2912, July, 1989.

14 Shalkhauser, M. J., "Satellite Ground TerminalUser Simulation', NASA TechnicalMemorandum 100234, January, 1988.

15 Nagy, L. A., "Satellite Range Delay Simulationfor a Matrix Switched Time Division MultipleAccess Network Simulation System', 13th AIAACommunication Satellite Systems Conference,March, 1990

16 Shalkhauser, K. A., Nagy, L. A., and Svoboda,J. S. "Rain Fade Simulation and Power

Augmentation for Satellite CommunicationSystems', NASA Technical Memorandum103134, September, 1990.

17 Fujikawa, G., Conroy, M. J., Saunders, A. L.,and Pope, D. E., "Experimental RadioFrequency Link for Ka-Band CommunicationsApplications', NASA Technical Memorandum100824, June, 1988.

18 lvandc, W. D., An&o, M., Nagy, L. A.,Budinger, J. M., and Shalkhauser, M. J.,"Satellite Matrix-Switched Time Division

Multiple Access Network Simulation andEvaluation', 13th AIAA CommunicationSatellite Systems Conference, March, 1990(NASA TP 2944).

11

Form ApprovedREPORT DOCUMENTATION PAGE OMB No. 0704-0188

Public reporting burden for this coflection of information is estimated to average 1 hour per response, Including the time for reviewing instructions, searching existing data sources,gathering and maintaining the date needed, and completing and reviewing the collectk:m of informatiOn. Send comments regarding this burden estimate or any other aspect of thiscollection of information, including suggestions fo*" reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Repods, 1215 JeffersonDavis H|ghway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188), Washington, De 20503.

L 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED

Technical Memorandum

4. TITLE AND SUBTITLE S. FUNDING NUMBERS

Evaluation of Components, Subsystems, and Networks for High Rate, High

Frequency Space Communications

6. AUTHOR(S)

Robert J. Kerczewski, William b. Ivancic,

and John E. Zuzek

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Lewis Research Center

Cleveland, Ohio 44135- 3191

9. SPONSORING/MONITORING AGENCY NAMES(S) AND ADDRESS(ES)

National Aeronautics and Space Administration

Washington, D.C. 20546- 0001

WU-316-30- 19

8. PERFORMING ORGANIZATION

REPORT NUMBER

E-6597

10. SPONSORING/MONITORINGAGENCY REPORT NUMBER

NASA TM-105274

AIAA-91-3423

11. SUPPLEMENTARY NOTES

Prepared for the Conference on Advanced Space Exploration Initiative Technologles cosponsored by AIAA, NASA,

and OAI, Cleveland, Ohio, September 4 - 6, 1991. Responsible person, John E. Zuzek, (216) 433 - 3469.

12a. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified - Unlimited

Subject Categories 17 and 32

12b. DISTRIBUTION CODE

13. ABSTRACT (Maximum 200 words)

The development of new space communications technologies by NASA has included both commercial applications and

space science requirements. At NASA's Lewis Research Center, methods and facilities have been developed for

evaluating these new technologies in the laboratory. NASA's Systems Integration, Test and Evaluation (SITE) Space

Communication System Simulator is a hardware-based laboratory simulator for evaluating space communications

technologies at the component, subsystem, system, and network level, geared toward high frequency, high data rate

systems. The SITE facility is well-suited for evaluation of the new technologies required for the Space Exploration

Initiative (SEI) and advanced commercial systems. This paper describes the technology developments and evaluation

requirements for current and planned commercial and space science programs. Also examined are the capabilities of

SITE, the past, present, and planned future configurations of the SITE facility, and applications of SITE to evaluation of

SEI technology.

14. SUBJECT TERMS

Space communications; High frequencies; Millimeter waves; Planetary exploration;

Testbed; Test facilities; Evaluation

17. SECURITY CLASSIFICATION

OF REPORT

Unclassified

18. SECURITY CLASSIFICATION

OF THIS PAGE

Unclassified

19. SECURITY CLASS;IFICATION

OF ABSTRACT

Unclassified

NSN 7540-01-280-5500

15. NUMBER OF PAGES

12

16. PRICE CODE

A03

20. LIMITATION OF ABSTRACT

Standard Form 298 (Rev. 2-89)

Prescribed by ANSI Std. Z39-18298-102