DIPLOMA WORK EDUCATIONALQUALIFICATION LEVEL MASTER INVESTIGATION OF MODULATION

DIPLOMA WORK EDUCATIONAL-QUALIFICATION LEVEL “MASTER” INVESTIGATION OF MODULATION SCHEME AND TRANSMITTER NONLINEARITY IMPACT ON ADS -B MESSAGES TRANSMISSION VIA SATELLITE LINK Performed by Bezsmertna D. V. Supervisor prof. Grekhov A. M

Approbation of work results Theses: 1. Grekhov A. M. Investigation of modulation scheme impact on ADSB messages transmission via satellite link/ A. M. Grekhov, D. V. Bezsmertna // XIII International scientific and practical conference of young researchers and students “Polit. Contemporary problems of science”. – National Aviation University, Kyiv. – 2013. 2. Kharchenko V. P. Investigation of modulation scheme and amplifiers nonlinearity on ADS-B messages transmission via satellite link / V. P. Kharchenko, A. M. Grekhov, D. V. Bezsmertna // International scientific and technical conference “AVIA-2013”. – National Aviation University, Kyiv (Ukraine). : NAU 2013. – Vol. 2. – P. 7. 50 -7. 53 Articles: Kharchenko V. P. Investigation of modulation scheme and transmitter nonlinearity impact on ADS-B messages transmission via OFDM satellite link/ V. P. Kharchenko, A. M. Grekhov, D. V. Bezsmertna // Bulletin of the National Aviation University. – 2014, in press.

Topic actuality • Air traffic increases steadily over the years that lead to the increase of flights through the Poles, oceans and regions with reduced radar coverage and current ATM network can’t handle with it. Thus, there is a need that standards of safety and efficiency should be maintained or even enhanced. • Therefore, there arises a necessity of conversion from the expensive ground-based systems to the cheap satellitebased systems that provide global coverage. • As a solution, there are used the latest Iridium satellite constellation and developed program of Automatic Dependent Surveillance Broadcast (ADS-B).

Goal and task of diploma work • to construct the original models of satellite communication channel "Equipped ADS-B aircraft-to-Iridium satellite-to-Ground Station“ • to investigate the dependencies of model parameters for ensuring efficient, accurate and high rate data transmission.

Next generation CNS / ATM system The developed communication subsystem Iridium Satellite System is LEO satellite communications services that provide voice and data communication anytime and everywhere on the Earth surface. Benefits: • Large satellite constellation that ensures global coverage; • Low propagation delays, low power requirements that provide direct interface with the system; • Provide service in the wake of a natural disasters; • Provide voice and data services.

The development of surveillance subsystem Automatic Dependent Surveillance Broadcast (ADS-B) is kind of surveillance that provide communication between aircrafts and between aircraft and the ground through data transmission link of broadcast type. Benefits: • Safer flight • Accurate Weather reports (FIS-B) • Terrain overlay • TIS –B information • Surrounding traffic information • Accurate Management

ADS-B and Iridium NEXT ADS-B technologies with Iridium LEO constellation provide global, real-time aircraft position information, weather information, full coverage over oceanic airspace, polar routes, remote and mountainous regions, where ground station network is impossible and impractical to employ.

Satellite communication link modeling

“Aircraft-to-Satellite-to-Ground Earth Station” link modeling Satellite Transponder Uplink Path Bernoulli Binary Generator Downlink Path Aircraft Uplink Transmitter FEC, BPSK, QPSK, 16 QAM, 64 QAM, OFDM transmitter Error Rate Calculation, SNR estimation Ground Station Downlink Receiver FEC, Demodulator, OFDM receiver

Model construction and function description Aircraft transmitter construction The transmitter generates random data which is sent over the channel. Before sending, signal has to be adapted to the channel conditions by using a specific adaptive modulation (BPSK, QPSK, 16 QAM, 64 QAM) and coding schemes. Transmitted data also use OFDM transmission technique: signal need to be conformed into an OFDM symbol by performing frequency-time transformation and addition of a guard period.

Satellite transponder, uplink and downlink path construction From aircraft transmitter signal is sent over the transmission channel in free space, during which losses and interferences arise. Then, data is received by transponder and retransmitted back to the ground station.

Ground station construction Ground station performs reverse operation of transmitter.

Aeronautical satellite channel simulation Dependencies of a SNR on free path losses for different modulation modes, transponder noise temperatures and channel bandwidths NOFDM=1; amplifier nonlinearity - disabled; transponder linear gain -1 d. B

Dependencies of a SNR on free path losses for different modulation modes, transponder noise temperatures, number of OFDM symbols Amplifier nonlinearity - disabled; amplifier linear gain - 1 d. B

Dependencies of a SNR on free path losses for different modulation modes and types of amplifier nonlinearity Tnoise= 20 K, NOFDM=1; B = 3. 5 MHz

Dependencies of a SNR on free path losses for different modulation modes and cyclic prefix values Tnoise= 290 K, NOFDM=1; B = 3. 5 MHz

Conclusion The most efficient, accurate high data transmission can be provided by an optimal combination of model parameters: modulation schemes, coding, noise temperature, channel bandwidth, number of OFDM and cyclic prefix. Obtained results: 1. The 64 QAM provides highest data transfer rate but sensitive to noises. BPSK and QPSK are more robust to the interferences; 2. The reduction of transponder noise temperature, channel bandwidth and cyclic prefix leads to more efficient data transfer; 3. The greater the number of OFDM the higher the value of SNR; 4. The higher the average input power, more accurate signal is received.

Conclusion Developed model of satellite communication channel allows to investigate and analyze the effectiveness of error detection and correction. It can be used for finding an optimal methods for ensuring efficient, accurate and high rate data transmission. It can be used as basic model for real satellite communication link investigation, development and construction in order to provide communication and surveillance between two airplanes and ground stations by using several satellites.

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