The recent applications of Unmanned Aerial Vehicles (UAVs) and Remotely Piloted Air Systems (RPAS) often require reliable and fast two-way communications between UAVs, base stations and consumers using terrestrial cellular networks. Two crucial questions are whether existing ground networks can effectively interact with UAVs in three-dimensional space during intensive traffic and under what data transmission modes it is possible to provide the necessary Quality of Service (QoS). To answer this question, the UAV/RPAS communication channel model "BS-ATM-HUB-RPAS" with a ground network was designed and investigated. The dependencies of dropped packets, message Travel Time (TT) and HUB Average Utilization on the Transaction Size (TS), the link bandwidth, the Bit Error Rate (BER) and the Packet Fail Chance for different distribution laws of Time Between Transactions (TBT) were analyzed. A significant benefit has been observed in using the LogNormal TBT distribution law rather than the Const and Exponential TBT distributions for the dependencies of dropped packets versus TS, HUB Average Utilization versus TS, and HUB Average Utilization versus link bandwidth. However, for the dependency of message Travel Time on the Transaction Size, the type of TBT distribution did not play a significant role; for all distributions, with increasing transaction size, the time of their transmission via the channel was increased. The importance and usefulness of such a numerical analysis lies in the ability to set traffic parameters and observe the resulting throughput, packet loss, and number of bit errors and QoS in a channel under certain transmission modes.
First built models of Remotely Piloted Air System (RPAS) communication channels based on Wideband Code Division Multiple Access (WCDMA) 3GPP Standard were designed. Base Station (BS) transmission within the Radio Line of Sight (RLoS) and through the satellite using Beyond Radio Line of Sight (BRLoS) was considered. The dependencies of the Bit Error Rate (BER) on the signal-noise ratio for different RPAS velocities and WCDMA сhannel models were obtained. The dependences of the BER on the signal-noise ratio for different levels of satellite transponder nonlinearity were studied. The dependence of the BER on the BS antenna diameter in case of the transponder nonlinearity was analysed. The dependencies for satellite channel characteristics, first obtained taking into account the motion of the RPAS, make it possible to predict the behavior of the communication system in critical conditions.
MIMO-OFDM models of RPAS communication channels based on LTE Standard were built. Dependencies of the BER on the SNR for Extended Pedestrian A and Extended Vehicular A models using 2-by-2 multiple antennas were obtained. Dependencies of the BER on the SNR for different levels of Frequency Offset at satellite transponder were studied.
For modelling transmission of ADS-B messages via low-orbit satellite constellation Iridium, the original model of a communication channel “Aircraft-to-Satellite-to-Ground Station” was built using MATLAB Simulink. The model comprises “Aircraft Uplink Transmitter” (Bernoulli Random Binary Generator, Convolutional Encoder, BPSK Baseband Modulator, High Power Amplifier with a memoryless nonlinearity, Transmitter Dish Antenna Gain), “Uplink Path” (Free Space Path Loss, Phase/Frequency Offset), “Satellite Transponder” (Receiver Dish Antenna Gain, Satellite Receiver System Temperature, Complex Baseband Amplifier, Phase Noise, Transmitter Dish Antenna Gain), “Downlink Path” (Free Space Path Loss, Phase/Frequency Offset), “Ground Station Downlink Receiver” (Receiver Dish Antenna Gain, Ground Receiver System Temperature, Viterbi Decoder), “Error Rate Calculation” block and “Display”. The modelling was realized without and with convolutional coding (r = 3/4, K = 7) at different noise temperatures and free space losses. Dependencies of a Bit Error Rate on free space path losses, antenna's diameter, phase/frequency off-sets, satellite transponder linear gain, aircraft and satellite transponder high power amplifier back-off level, and phase noise were received and analysed.
Для моделювання передачі ADS-B повідомлень за допомогою низкоорбитального сузір'я супутників Іrіdіum звикористанням програмного комплексу NetCracker Professіonal 4.1 побудовано оригінальні моделікомунікаційного каналу «Літаки-Супутники-Наземні станції». Вивчено вплив кількості літаків і супутників насереднє завантаження каналу донизу і час передачі повідомлень. Розглянуто різні архітектури телекомуніка-ційних каналів: тільки з міжсупутниковими зв'язками та зв’язками «Супутник-Земля-Супутник». Дослідженоефект «насичення» каналу зв'язку при одночасній передачі даних через один канал супутникового зв’язку відбагатьох літаків.
Original models of RPAS communication channels based on IEEE 802.11b Standard, including both Base Station transmission within the Radio Line of Sight, and through the satellite using Beyond Radio Line of Sight, were built. Dependencies of the Bit Error Rate on the Signal-Noise Ratio for different payload data rates were obtained. Transponder nonlinearity and Base Station antenna diameter impact were analysed.
Remotely piloted air systems (RPASs) are increasingly used for data transmission in the space‐air‐ground integrated networks (SAGINs). That is why it is important to know the possibilities and ways of integrating existing space, air and terrestrial networks for effective interaction with RPASs. This paper studies the issues of ensuring the required quality of service during heavy traffic in SAGIN and the choice of the necessary data transmission modes for this. Models of communication channels were created, including line‐of‐sight transmission (Model 1), public terrestrial network (PTN) (Model 2), low‐orbit satellite transmission (Model 3) and PTN plus satellite transmission (Model 4). The relationships between models' performance and traffic parameters, channel bandwidths, bit errors, lost packets and models' topology were investigated using NetCracker Professional 4.1 software. The dependencies of the average utilization on the transaction size and the time between transactions with different statistical distribution laws were analyzed. The effect of different bandwidths was investigated. The influence of the bit error rate and the probability of packet fail chance on the channel performance was studied. The traffic characteristics in all models were compared.
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