Satellite Transponder Research Articles

Pseudo‐Random Code Generator Design for Satellite Transponder of 5G Wireless Networks

AbstractIn satellite communication systems, a data stream for a direct sequence spread spectrum transmitter is multiplied by a pseudo‐random code. It can then be transmitted over the same microwave channel as multiple users. Correlating the received composite signal with the provided pseudo‐random code at the receiver end will extract the original data stream without interference. The proposed transponder models here are to achieve the objective of minimizing the satellite onboard components, increasing the speed of operations for higher bandwidth, and transmitting more information to a large group of users. However, taking advantage of this technology and overcoming the challenges of implementing it in a real‐time environment, a satellite transponder was designed at a speed of 128 bps. The satellite transponder here is to accommodate satellites interconnecting 5G wireless networking systems. This paper describes the useful roles of pseudo‐random code generations and the methods of applications to track the desired binary data bit sequences according to the preferred carrier frequency channels. The designed transponder schematic circuit was tested for the received uplink signal at the carrier frequency 13 GHz and transmit downlink signal at 11 GHz. To evaluate the designed onboard transmitter system performance, initially, the system was analyzed in terms of energy per bit‐to‐noise power spectral density ratio, bit error rate, and finally signal‐to‐noise power ratio. The design system was measured for the operations with minimum bandwidth of 100 MHz upto 1.28 GHz for the input bit rates of 200 Mbps upto 2.56 Gbps respectively.

Development Overview Of Communication Satellites For Television Transmission

This paper presents a survey of data related to development of the communication satellites for TV broadcasting, located in the geostationary orbit, for the period starting with the emergence of the first commercial satellite television broadcasting in 1965 up to 2023. It presents development of the satellite network technology through the number of satellites and active satellite transponders in the Ku and C bands at the end of each year for the mentioned period. These numbers are presented graphically for differentgeographical zones

Artificial Neural Network Modeling of a CMOS Differential Low-Noise Amplifier Using the Bayesian Regularization Algorithm.

The purpose of this communication is to present the modeling of an Artificial Neural Network (ANN) for a differential Complementary Metal Oxide Semiconductor (CMOS) Low-Noise Amplifier (LNA) designed for wireless applications. For satellite transponder applications employing differential LNAs, various techniques, such as gain boosting, linearity improvement, and body bias, have been individually documented in the literature. The proposed LNA combines all three of these techniques differentially, aiming to achieve a high gain, a low noise figure, excellent linearity, and reduced power consumption. Under simulation conditions at 5 GHz using Cadence, the proposed LNA demonstrates a high gain (S21) of 29.5 dB and a low noise figure (NF) of 1.2 dB, with a reduced supply voltage of only 0.9 V. Additionally, it exhibits a reflection coefficient (S11) of less than -10 dB, a power dissipation (Pdc) of 19.3 mW, and a third-order input intercept point (IIP3) of 0.2 dBm. The performance results of the proposed LNA, combining all three techniques, outperform those of LNAs employing only two of the above techniques. The proposed LNA is modeled using PatternNet BR, and the simulation results closely align with the results of the developed ANN. In comparison to the Cadence simulation method, the proposed approach also offers accurate circuit solutions.

Transmission experiments for apsk modulation signals with digital pre-distortion over 12-GHz-band broadcasting satellite

The UHDTV satellite broadcasting services in the 12-GHz-band were launched in Japan in December 2018. The satellite transmission system was standardized in Japan as ISDB-S3 and in ITU-R as Rec. BO. 2398. To improve its transmission performance, we are researching a digital pre-distortion (DPD) technique to compensate for distortion arising from the radio frequency (RF) component in the satellite transponder. We have developed an ISDB-S3 transmitter with our proposed DPD and demonstrated its effectiveness over a 12-GHz-band satellite transponder simulator in laboratory experiments. In this study, we evaluated the transmission performance for 32-amplitude phase shift keying (APSK) with DPD over the 12-GHz-band broadcasting satellite BSAT-4b.

Four-channel all-optical wavelength conversion unit based on nonlinear effect of three-section monolithically integrated semiconductor lasers.

A simple and highly efficient four-channel all-optical wavelength conversion based on four-wave mixing effect of the directly modulated three-section monolithically integrated semiconductor laser is proposed and experimentally investigated. For this wavelength conversion unit, the spacing of the wavelength can be adjusted by tuning the bias current of the lasers and setting it to be 0.4nm (50GHz) as a demonstration is this work. A 50Mbps 16-QAM signal centers at 4-8GHz is experimentally switched to a targeted path. Up- or downconversion depends on a wavelength-selective switch, and the conversion efficiency can reach up to -2 to 0dB. This work provides a new technology for photonic radio-frequency switching matrix and contributes to the integrated implementation of satellite transponders.

Channel Selectivity of Satellite Transponders with the Antenna Combined with a Size-Reduced Metallic Waveguide Bandpass Filter Having Thin Metamaterial Resonators.

Global and intercontinental networking relies on satellite communication. Its wireless communication system always has antennas and their feed assembly comprising waveguides. This makes the satellite payload heavy and costly. In this paper, a novel method is proposed to effectively reduce the size of a waveguide bandpass filter (BPF). Because the metallic cavities make the conventional waveguide end up with a large geometry, especially for high-order BPFs, very compact waveguide-type resonators having metamaterial zeroth-order resonance (WG-ZOR) are designed on the cross-section of the waveguide and substituted for the cavities. While the cavities are half-wavelength resonators, the WG-ZOR is shorter than one eighth of a wavelength. A substantial reduction in size and weight of the waveguide filter is observed as the resonators are cascaded in series through coupling elements in the X-band much longer than K- or Ka-band. An X-band of 7.25~7.75 GHz is chosen to verify the method as the passband with attenuation of 40 dB at 7.00 GHz and 8.00 GHz as the roll-off in the stopband. The BPF is manufactured using the CNC milling technique. The design is carried out with geometrical parameters, not of the level of 10 μm, but the level of 100 μm, which is good for manufacturers but a big challenge for component designers. The measurement of the manufactured metal waveguide filter reveals that the passband has about ≤1 dB and ≤-15 dB as insertion loss and reflection coefficient and the stopband has ≤-40 dB as attenuation, which are in good agreement with the results of the circuit and simulation. The proposed filter has a length of 3.5 λg as the eighth-order BPF, but the conventional waveguide is 5 λg as the seventh-order BPF for the same area of the cross-section. This metamaterial BPF is combined with a horn antenna. The filter enables the wide-band antenna to distinguish the band of transmission from that of noise suppression. This channel selectivity is obviously observed by the filter integrated antenna test.

Analysis of the effectiveness of methods for ensuring the reliability of a communication satellite transponder

Objectives . Since the launch of satellite communication systems in practical use, approaches towards enhancing their operational quality and durability have been developing in the direction of increased reliability of airborne transponders. This is mainly achieved by increasing redundancy and using components with a lower failure rate. In this regard, the creation of new technologies and new materials is a particularly promising direction. However, since durability testing of complex systems can take several years, the problem of ensuring an effective combination of redundancy methods and elements having a reduced failure rate remains challenging. The purpose of the work is to analyze the effectiveness of methods for ensuring the reliability of a communication satellite transponder based on a proposed methodology for determining the durability index using a mathematical model of the probability of failure-free operation. Methods . In order to describe the complex structure of a satellite communication system transponder, a logical- probabilistic method is used, in which the dependence of the system reliability indicators on the reliability indicators of the transponder elements is formulated as a logical function of operability. Mathematical models of system reliability are created on this basis including for redundant systems. Graphs and analytical methods are used to compare different systems. Results . The influence of various methods for ensuring the redundancy of transponder devices and the use of more reliable components on the reliability and durability indicators is considered. A gamma-percentage resource-based technique for determining the durability indicator based on the constructed mathematical models of the probability of failure-free operation is presented along with a comparative analysis of measures to increase the gamma-percentage resource of the transponder. Conclusions . The presented method for determining the durability index using a mathematical model of the probability of no-failure operation can be used to determine the time interval within which redundancy increases the probability of no-failure operation as compared with a decrease in the failure rate of elements. On this basis, the most effective combination of redundancy methods and approaches for reducing the failure rate of elements can be identified.

Interference Analysis of 5G NR Base Stations to Fixed Satellite Service Bent-Pipe Transponders in the 6425–7125 MHz Frequency Band

Future deployment of 5G NR base stations in the 6425-7125 MHz band raises numerous concerns over the long-term impact on the satellite transponders located in geostationary orbit. To study this impact and understand whether 5G NR may cause adverse effect to the spaceborne receivers, the research which estimated the interference levels to the satellite bent pipe links was done. The study presents the evaluation of aggregate interference from 5G NR base stations located inside the victim satellites' footprints using Monte-Carlo analysis and calculation of signal-to-noise degradation and bit error rates of the fixed-satellite service (FSS) bent-pipe transponders for each scenario. The results of the study showed the feasibility of co-existence between 5G NR and satellite systems in the 6425-7125 MHz bands, and that no negative impact on the performance of the satellite links is expected.

Development of Transmitter and Receiver With Set Partitioning 64APSK Coded Modulation Designed on Basis of Channel Capacity

In this paper, we present a prototype transmitter and receiver with set partitioning (SP)-64 amplitude and phase shift keying (APSK) coded modulation we developed for expanding satellite transmission capacity. SP-multi-level coded modulation is a transmission scheme that can improve noise immunity by properly combining a modulation scheme, bit allocation, and error-correction codes. We designed SP-64APSK coded modulation on the basis of channel capacity for expanding satellite transmission capacity. We confirmed that it has higher robustness to additive white Gaussian noise (AWGN) than DVB-S2X’s 64APSK modulation with Gray mapping through computer simulation. We also developed a prototype transmitter and receiver to implement our SP-64APSK coded modulation and evaluated its transmission performances in an AWGN channel and in a non-linear channel simulating 12-GHz-band satellite transponder characteristics. We describe the method of designing our SP-64APSK coded modulation through computer simulation, the modulation/demodulation process, and transmission performances of the prototype transmitter and receiver. We also indicate that 8K ultra-high definition television (UHDTV) with an encoded bit rate of 150 Mbps can be transmitted using the prototype within 34.5 MHz, which is the bandwidth of a single transponder for satellite broadcasting in Japan.

Analysis of digital pre-distortion with I/O interfaces for analog baseband signal over broadcasting satellites

Broadcasting satellite systems currently use multilevel modulation schemes, which are vulnerable to non-linear distortion, while their on-board amplifiers operate near the saturation point. We have developed a digital pre-distortion (DPD) embedded transmitter and demonstrated its effectiveness over a 12-GHz-band satellite transponder. To improve its versatility, we developed an external DPD adder, which enables existing transmitter to give an analog baseband signal its function. In this study, we confirm the effectiveness of the external DPD adder by evaluating the transmission performance of 64APSK over the satellite transponder.

A Method for Measuring the Group Delay of an On-Orbit Satellite Transponder

As one of the important parameters of the satellite transponder, the group delay of the transponder not only determines the magnitude of the signal transmission delay that is generated by the system or network but is also closely related to the signal transmission distortion, which has a substantial impact on the signal transmission quality. When the satellite is in orbit, it is difficult to measure this index due to the particularity of its position. To overcome this problem, this paper proposes a method for measuring the group delay of an on-orbit satellite transponder. By using two sets of ground station antenna systems that are installed in parallel to conduct the observation of the transponders to be measured simultaneously in the mode of “receiving its own station-disseminated signal,” the measurement results of the group delay of the transponders can be obtained after the calculation. Based on the orbit determination by the transfer tracking system of the National Time Service Center, a group time delay measurement experiment of the C5B transponder of the APSTAR-7 satellite in orbit was conducted. The results of an analysis of the data demonstrate that this method can effectively measure the group delay of a satellite transponder and that the root mean square of the two measurement results is less than 0.2 ns, which provides a useful reference for further optimization and improvement of the orbit determination accuracy of the system and provides a performance evaluation service for satellite companies.

Application of AsiaSat-3S satellite in CAPS system

CAPS is an integrated system of navigation and communication. The orbit position of AsiaSat-3S satellite has been pushed from 105.5E to 147.5E. It has become a SIGSO satellite, which plays a certain role in improving the constellation DOP of CAPS navigation system. According to the characteristic parameters of AsiaSat-3S satellite (mainly including orbit parameters, polarization parameters, frequency offset parameters, etc.), this paper expounds the changes of azimuth, elevation angle and polarization angle of 16-meter paraboloid antenna in Tianjin pointing and tracking AsiaSat-3S satellite in CAPS ground system, and analyzes the dynamic changes of frequency offset of AsiaSat-3S satellite transponder through the spontaneous receiving of navigation signals The parameter model prediction of CAPS repeater navigation system has a good reference value.

Real-time frequency transfer system over ground-to-satellite link based on carrier-phase compensation at 10−16 level* *Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0302101) and the Initiative Program of State Key Laboratory of Precision Measurement Technology and Instruments.

We demonstrate a novel and stable frequency transfer scheme over ground-to-satellite link based on real-time carrier-phase detection and compensation. We performed a zero-baseline measurement with the designed system, an uninterrupted frequency standard signal is recovered in the reception station without additional post-correction of delay error caused in the route, which is because the phase error of the entire route is tracked and compensated continuously in real-time. To achieve this goal, we employed two carriers in the system and the differential signal is transferred in order to eliminate the instability results from the local oscillator at the satellite transponder as well as the common-mode noise induced in the transfer route and microwave components. The stability of 3 × 10−16 with an integration time of 1 day was achieved and the time fluctuation during one day was measured to be about ±20 ps. Error sources and possible solutions are discussed. Our zero-baseline method shows a promising result for real-time satellite-based time and frequency transfer and deserves further research to find whether it works between long-baseline stations.

High-precision carrier phase timing method with single communication satellite and the test campaign

A test campaign for carrier phase timing was conducted on the BDS/GNSS Open Testing Platform (BOTP), which was established by the National Time Service Center, Chinese Academy of Sciences (NTSC, CAS), using communication satellites in geosynchronous orbit. Its purpose was a navigation technology experiment and verification platform for BDS and GNSS. The system architecture of BOTP, a novel navigation system independent of GNSS, is similar to that of traditional GNSS, with the main difference being that the communication satellite transponder without an onboard atomic clock is used as the navigation satellite. Moreover, the navigation signal generated at the ground navigation station is transmitted to the communication satellite via a large-diameter antenna and is transparently retransferred by the satellite transponder to users. BOTP uses a high-performance stable ground atomic clock group instead of an onboard satellite atomic clock, and the navigation signals work in the C-band. Based on the various merits of BOTP, a novel timing method with a single communication satellite is proposed, and the results of a performance verification test campaign conducted by NTSC in Xi’an, Beijing and Sanya during June 2020 are described. The statistics show that (1) the standard deviations of the carrier phase timing are 0.061 ns, 0.556 and 0.828 ns at Xi’an, Beijing and Sanya, respectively, and (2) the corresponding 95% confidence intervals of the carrier phase timing are 0.114 ns, 1.259 ns and 1.695 ns. These results reflect the ability and potential application of BOTP for high-precision, real-time timing based on the carrier phase.

Optimization Method of Dynamic Beam Position for LEO Beam-Hopping Satellite Communication Systems

The beam-hopping (BH) technology applied to low earth orbit (LEO) satellite communication networks is a superior choice, but the long transmission delay partly caused by data packets waiting in the queue of satellite transponders will seriously affect the user experience. To shorten the packet queueing delay, in this paper, we propose an optimization method of dynamic beam position division for LEO BH satellite communication systems. Firstly, we analyze the packet queueing delay problem in BH satellites to find out the factors related to the queueing delay, and we find that the number of beam positions is negatively correlated with the queueing delay. Then, we turn the beam position division problem into a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$p$ </tex-math></inline-formula> -center problem to try to cover all users with the least number of beam positions. The beam positions among the footprint of LEO satellites are determined dynamically by the user distribution and the traffic distribution. Finally, the performance evaluation of the proposed optimization method is carried out in real-time and the simulation shows that the beam position division optimized system we proposed can shorten the queueing delay up to 40% compare to the benchmark system without sacrificing throughput.

Comprehensive Feasibility Study on Direct Spectrum Division Transmission over Multiple Satellite Transponders

Comprehensive Feasibility Study on Direct Spectrum Division Transmission over Multiple Satellite Transponders

System Throughput Gain by New Channel Allocation Scheme for Spectrum Suppressed Transmission in Multi-Channel Environments over a Satellite Transponder

System Throughput Gain by New Channel Allocation Scheme for Spectrum Suppressed Transmission in Multi-Channel Environments over a Satellite Transponder

A Novel Channel Amplitude and Phase Correction Algorithm Based on Phased Array Space-based TT&C Communication

According to the characteristics of phased array space-based TT&C satellite antenna aperture size and transponder power limitation, this paper proposes a correction algorithm based on PN code and BPSK without data modulation. At the same time, combined with multi-period coherent accumulation, the channel amplitude and phase correction accuracy is guaranteed under low signal-to-noise ratio. From the simulation test, we can see that our method has the characteristics of low interception and anti-barrage jamming.

Design of a Fully Digital BPSK Demodulator Integrated into a TT&amp;C Satellite Transponder

One challenge in satellite development concerns to the performance of the communication link and the adopted technology. In this paper, we present the design of a fully-digital BPSK demodulator that is part of a satellite on-board telemetry, tracking and command transponder. The calculations for the determination of several project parameters, the block diagrams and equations of all the functional modules compounding the demodulator are described. The architecture of the demodulator and of some functional modules differs from similar solutions found in the literature. The performance of the proposed demodulator was evaluated by mathematical analysis and computational simulation. Some of such analyzes are original as well as some statistical characterizations of the signals that were done via simulation. In addition, we evaluated the system bit error rate, under various operating conditions, and the variance of the parameters estimated by the carrier and the symbol synchronizers. The results demonstrated that the proposed solution complies with the requirements of the project. In the worst case of operation, the system performance is only 0.3 dB below the theoretical limit, for the condition when the bit error rate is equal to 10^-5.

Performance of Multibeam Very High Throughput Satellite Systems Based on FSO Feeder Links With HPA Nonlinearity

Due to recent advances in laser satellite communications technology, free-space optical (FSO) links are presented as an ideal alternative to the conventional radio frequency (RF) feeder links of the geostationary satellite for next generation very high throughput satellite (VHTS) systems. In this paper, we investigate the performance of multibeam VHTS systems that account for nonlinear high power amplifiers at the transparent fixed gain satellite transponder. Specifically, we consider the forward link of such systems, where the RF user link is assumed to follow the shadowed Rician model and the FSO feeder link is modeled by the Gamma-Gamma distribution in the presence of beam wander and pointing errors where it operates under either the intensity modulation with direct detection or the heterodyne detection. Moreover, zero-forcing precoder is employed to mitigate the effect of inter-beam interference caused by the aggressive frequency reuse in the user link. The performance of the system under study is evaluated in terms of the outage probability, the average bit-error rate (BER), and the ergodic capacity that are derived in exact closed-forms in terms of the bivariate Meijer’s G function. Simple asymptotic results for the outage probability and the average BER are also obtained at high signal-to-noise ratio.