Satellite Broadcasting System Research Articles

Energy Efficiency for Faster-than-Nyquist Data Transmission Using Processing Algorithms with Decision Feedback

One of the ways to increase the volume of transmitted information is to increase the bit rate above the Nyquist barrier. However, an increase in bit rate in the case of FTN (Faster-Than-Nyquist) signals leads to an increase in energy costs for receiving information on channels with limited bandwidth, for example, in Digital Video Broadcasting satellite systems like DVB-S2/S2X. It is possible to minimize energy losses by using the processing algorithm “maximum likelihood sequence estimation”. However, the computational complexity of this algorithm is extremely high, which limits its use, especially in terrestrial mobile satellite terminals. We propose a new bit-by-bit decision feedback algorithm with maximum likelihood ratio estimation of subsequent symbols in the observation interval. This algorithm provides minimal energy costs comparable to the method “maximum likelihood sequence estimation” at speeds 2–3 times higher than the Nyquist barrier. At the same time, the complexity is two orders of magnitude less. It is shown by simulation for a channel with additive noise that energy losses in relation to the potential bit error rate (BER) are less than 4.5 dB. In the presence of Rayleigh fading, the application of the proposed algorithm makes it possible to provide the processing of FTN signals for double bit rates in urban areas with energy costs equal to 12 dB when using an equalizer. We give numerical estimations of the increase in computational complexity for the proposed processing algorithm. It is shown that an increase in the bit rate by 1.5 times leads to an increase in the computational complexity by more than an order of magnitude. The same conclusion can be reformulated in another form: for the proposed algorithm, each decibel of energy gain is achieved by increasing the number of computational operations by 1.5×105. It is experimentally shown that additional energy losses due to non-ideal phase and timing synchronization are no more than 1 dB when the proposed algorithm is applied in a fading channel. The energy costs in fading channels relative to a stationary channel for twice the Nyquist rate are equal to 13.8 dB when using an equalizer.

A miniaturized left‐handed circularly‐polarized printed radiator for direct broadcast satellite application

SummaryThis article presents a highly compact printed radiator for direct broadcast satellite (DBS) systems that exhibits good gain and left‐handed circular polarization. The inferred pattern is accomplished by etching two isosceles triangles, one from each of the four corners of a square. From the center of the newly acquired structure, a circular geometric design is made up of 16 isosceles‐scaled triangles has been etched. This arrangement induces resonance in the antenna, aligning it with the desired frequency. The proposed antenna is designed using PCB laminated Rogger 5880 material and simulated in a CST EM simulator. The antenna under consideration exhibits a significant size reduction, achieving a miniaturization ratio of 21.03%. The LHCP antenna resonated at 12.61 GHz and offered a decent LHCP gain of 7.95 dBic. It gives 0.56 GHz CP bandwidth, which covers the DBS service band entirely. It also provides 96.43% radiation efficiency and 44.27 dB/m correction factor, respectively. All the measured findings of the prototype agree with its simulated one.

From the History of the Development of Russian Space Television

The article examines the activities for the development of the space television system in Russia. The date of birth of the national space television is October 7, 1959. It is the day of the beginning of the radio and television transmission of images of the far side of the Moon to Earth. In 1971, the international satellite communication and broadcasting system Intersputnik was created in the USSR. Soon after the beginning of its development, the control of the Earth from space for the purposes of space surveillance and aerospace defense became an important function of space television.

A printed tiny-RHCP antenna for direct broadcast application

The present study unveils a printed antenna design that achieves high gain and exhibits right-handed circular polarization (RHCP). The antenna is intended for use in direct broadcast satellite systems, operating within the frequency range of 12.20 to 12.70 GHz. The specified configuration is achieved by etching a pair of indistinguishable isosceles triangles from the vertex of a geometrically regular square. A circular geometric structure consisting of sixteen isosceles triangles scaled in proportion is meticulously engraved from the central point of the recently obtained geometry. The meticulous etching enhances the antenna’s effective length, which in turn helps achieve improved parametric performance at the desired frequency. The antenna under consideration was simulated using a SONNET EM simulator, cross-verified by the CST microwave studio, and afterward, it was fabricated using a cost-effective PCB laminated Rogger 5880 material. The antenna under consideration significantly reduces size, achieving miniaturization of 20.20%. The antenna is resonated at 12.52 GHz, and it exhibited a satisfactory circularly polarized gain of 8.46 dBic. It also provides a CP bandwidth of 0.54 GHz, capable of covering the entire DBS band. Additionally, it offers 97% radiation efficiency and 86% aperture efficiency. The antenna also offers 23 dB/m correction factor, which highlights its minimal EMI/EMC effects. All the measured outcomes align with the results achieved from the simulator.

Wideband single-feed dual circularly polarized multi-beam transmitarray antenna based on receiver–transmitter metasurface

In this paper, a novel metasurface (MS) as well as a generalized dual-circular-polarized (CP) decoupled modulating method are proposed. The proposed MS can realize high-efficiency dual-spin transmissions with equal-magnitude upon left handed circular polarization (LCP) incidence across 9–12.5 GHz. This MS is constructed based on the receiver–transmitter configuration, and the receiver layer composed of an LCP patch resonator while the transmitter layer is a linearly polarized patch resonator. Rotating the receiver and transmitter patches separately can impose identical and conjugated geometric phase modulations for the dual-CP transmission waves, respectively. Hence, through an elaborate combination of the dual geometric phases, totally decoupled and dispersion-less phase modulations for transmitted dual-spin waves can be obtained. As the proof of its uses in practical applications, we have designed a single-feed dual-CP dual-beam transmitarray antenna (TA) and a dual-CP quad-beam TA. The second TA is also fabricated and tested. The measured results are consistent with the simulated results, showing that the TA achieves peak aperture efficiency of 49% at 9.5 GHz, with 1 dB gain bandwidths (BWs) of the dual-CP quad-beams all larger than 24.5% while 3 dB axial ratio BWs all larger than 54.5%. The proposed wideband and high-gain dual-CP multi-beam TAs may have promising prospects for many applications such as vehicle-satellite communication systems, satellite broadcasting and coverage systems.

Dual-Layer Beamscanning Reflectarray Antenna Operating at Ku-Band

This paper presents a beam scanning electronically reconfigurable reflectarray configuration for Ku-band applications using a single varactor diode. A 15×15 center-fed reconfigurable reflectarray antenna is designed consisting of 225 octagonal shaped unit cells. The proposed tunable element has a unit cell size of 9.8 mm, developed on a 1.575 mm thick Taconic TLY-5 substrate. A single varactor diode is integrated with the tunable element to produce a reflection phase variation of 340° at 14.1 GHz. In this work, both the varactor and biasing circuit are placed beneath the substrate to avoid unexpected reflections, which leads to achieving a pencil beam of 8.1° beamwidth. The simulation results of the reconfigurable reflectarray antenna (RRA) shows good beam-scanning radiation performance of scanning range ±30° and a peak gain of 27.6 dBi. This structure provides a convenient solution for Ku-band distinctive applications like uplink operation in the direct broadcast satellite system, digital video broadcasting, earth exploration satellites, space research satellites, and defense systems.

Feeder Link Precoding for Future Broadcasting Services

5G systems are becoming a reality and the evolution toward beyond 5G and 6G systems is already being defined, also to cope with the ever increasing capacity demanded by on-ground users. This will pose challenging requirements on the feeder link of future satellite systems, which risks to become a bottleneck for the overall system performance. In this article, we propose a novel architecture of linear precoding for the feeder link of a broadcast satellite system operating with full frequency reuse to significantly enhance the achievable capacity. The architecture has been simulated and tested in a challenging multifrequency scenario, where Ku, Ka, Q/V, and W bands have been considered for transmission. The numerical performance analysis and the open issues related to the practical realization of the proposed architecture are also thoroughly discussed.

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.

Active and Passive Components for Broadband Transmit Phased Arrays: Broadband Transmit Front-End Components

Phased-array antennas have penetrated a large application space, and in this article, we present some of the critical components for phased-array front ends, as described in <xref ref-type="fig" rid="fig1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Figure 1</xref> . We focus on an octave-bandwidth 6- to 12-GHz transmit implementation, but the methodology and component designs are scalable in frequency. Over the past few decades, phased-array applications have expanded from radar to wireless and satellite communications, as well as medical imaging and various sensing modalities. By tracking users with individual high-gain beams, spatial multiplexing enables cochannel interference mitigation, enhancing signal levels, and power management in wireless communications systems. For example, <xref ref-type="bibr" rid="ref1" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[1]</xref> shows a 64-element phased-array transceiver operating in the 28-GHz band with 52-dBm effective isotropic radiated power (EIRP) for 5G applications with up to 12 Gb/s of throughput, and <xref ref-type="bibr" rid="ref2" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[2]</xref> demonstrates a system-level development of a 384-element, 16-tile, W-band phased array with 52-dBm EIRP in 0.18-μm silicon–germanium bipolar CMOS (BiCMOS) technology. In satellite broadcasting and communication systems, phased-array antennas enable beam shaping over countries and continents, tracking at the end-user side, and rain fading mitigation, e.g., <xref ref-type="bibr" rid="ref3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[3]</xref> . In <xref ref-type="bibr" rid="ref4" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">[4]</xref> , advances in phased arrays for satellite applications developed at Lockheed Martin are described from an industry perspective.

High Q Dielectric Titanium Tellurite Thick Films on Alumina Substrates for High Frequency Telecommunications

The vital role of high-quality-factor (Q) high-frequency (f) dielectric resonators in the growing microwave telecommunication, satellite broadcasting and intelligent transport systems has long motivated the search for new, small size, and lightweight integrated components and packages, prepared by low cost and sustainable processes. One approach is replacing the currently used bulk ceramic dielectrics by thick films of low-sintering-temperature dielectrics fabricated by affordable processes. Here we demonstrate the fabrication of high-Q TiTe3O8 thick films directly on low loss Al2O3 substrates by electrophoretic deposition using sacrificial carbon layer. Nineteen-micrometre-thick TiTe3O8 films on Al2O3 sintered at 700 °C are found to have a relative permittivity εr of 32 and Q × f > 21,000 GHz. Being thus able to measure and provide for the first time the microwave dielectric properties of these films, our results suggest that TiTe3O8 films on Al2O3 substrates are suitable for microlayer microstrip array applications.

Design and Implementation of a Multiband Metamaterial-Loaded Reconfigurable Antenna for Wireless Applications

This article presents a multiband antenna with the implementation of a metamaterial split-ring resonator (SRR), quasicomplementary split-ring resonator (CSRR), and slots to achieve octaband characteristics for wireless standards. Multiband features are accomplished by the implementation of the slot approach within the radiating section part and loading the SRR and CSRR cells. The electrical dimension is 0.256λ × 0.176 λ × 0.0128λ (32 × 22 × 1.6 mm3) of the proposed design, at a lower frequency of 2.4 GHz. The proposed design indicates the frequency-band reconfigurability nature by using the switching PIN diode placed at the slotted section of the ground plane. During the OFF state of switching, the element structure resonates in eight wireless communication bands covering various high-speed multiple applications of Internet of Things (IoT) regarding wireless standards S-band WLAN (WiFi, Bluetooth, Z-wave, wireless HART, and WBAN), lower C-band (WAIC, satellite communication transmission application), C-band WLAN, X-band (ITU region 2), Ku-band (direct broadcast satellite system and terrestrial microwave communication system service), and K-band (radar communication application) at 2.4, 4.3, 5.8, 8.5, 11.1, 13.9, 16.1, and 18.9 GHz, respectively, with S11 ≤ −10 dB. The antenna achieves an optimum peak gain of 4.23 dBi and radiation efficiency of 82.78% at operating frequency regarding wireless standards. The average efficiency of the proposed design is more than 70% for all resonant modes. The radiation characteristics (gain/efficiency/patterns/impedance matching) are shown in the stable and improved form at achieved wireless modes.

China’s “National Spatial Infrastructure” and global governance: Chinese way of Military–Civil Fusion (MCF) over the ocean

ABSTRACT China is constructing an overwhelming satellite network, called the “National Spatial Infrastructure”, that might change the security and economic operations of global governance. Xi Jinping’s Military–Civil Fusion (MCF) strategy is founded on this system. Along with the well-known BeiDou Navigation Satellite System (BDS), the remote sensing satellite system and the communication and broadcasting satellite system form this new infrastructure. China is using it to establish a strong monitoring capability by: collecting various data on vessels’ navigation and oceanography; developing a huge communication network that covers actors and objects on the ocean as well as in the sky and the space; reforming its fishery administration and establishing new laws that enable the authorities to mobilise the numerous Chinese fishermen operating in global waters; and cultivating people-friendly apps to invite more users into the Chinese systems. Based on its strong victimhood mentality that calls for “great rejuvenation of the Chinese nation”, the Xi Jinping administration is trying to initiate a new human age by developing advanced technology and integrating it with social implementation that aims to increase China’s influence over the globe.

A Reduction of Peak-to-Average Power Ratio Based Faster-Than-Nyquist Quadrature Signals for Satellite Communication

The increase in the throughput of digital television and radio broadcasting (DVB) channels can be achieved due to application of signals with a compact spectrum and a relatively small peak-to-average power ratio (PAPR). The reason is the usage of traveling wave tubes (TWT) for amplifying and transmitting signals from a satellite repeater in DVB-S2X systems. At the same time, given that the bandwidth allocated for transmission should be used as efficiently as possible, a high reduction rate of out-of-band emissions level is required. The most effective solution in this direction is the transition to spectrum-economic signals, such as optimal Faster-Than-Nyquist (FTN) signals, which can provide a certain reduction rate of the out-of-band emissions level and minimum acceptable PAPR. This article proposes a method for obtaining optimal FTN pulses, which have symmetry in time domain, with specified PAPR and reduction rate of out-of-band emissions for the quadrature phase shift keying (QPSK) and offset quadrature phase shift keying (OQPSK). The possibility of synthesizing signals with OQPSK modulation is presented theoretically for the first time. Optimal FTN signals can provide PAPR reduction by at most 3 dB and outperform known root raised cosine (RRC) pulses. The simulation model adopts an architecture for quadrature generation of optimal FTN signals with OQPSK modulation with blocks for adjustable pre-amplification, clipping, and power amplification. The proposed signals can be used to increase the spectral and energy efficiencies of satellite broadcasting systems, such as DVB-S2/S2X, as well as low-rate return channels of interactive broadcasting systems with a frequency resource shortage.

Performance of the DBS Satellite Receiver under the Impact of Rainfall and Terrestrial Interference

This article presents a new study on the feasibility of operating a direct broadcasting satellite (DBS) system under the effect of both precipitation and interference from a fixed service (FS) at K‐band in a semiarid region. The carrier‐to‐noise plus interference ratio (CNIR) as a protection criterion has been adopted to make sure that the receiver of the DBS system operates with an acceptable performance under rainfall and interference from FS. Various measured data for rainfall in different areas have been utilized to investigate different rain rate exceedance percentages. Results have been shown that areas with high rain rates have a small CNIR at the DBS receiver and require large protection distances compared to low‐rain rate areas and vice versa. Some mitigation techniques have been suggested to alleviate the effect of rain and terrestrial interference on the DBS receiver performance.

Flexible Satellite Direct-to-Home Services With Layered-Division Multiplexing

Layered Division Multiplexing (LDM) has demonstrated increased data rate capacity for wireless applications where the service bitrates being multiplexed are unbalanced. Current Direct-To-Home (DTH) broadcasting satellite standards (DVB-S2 and DVB-S2X) include Variable Coding and Modulation (VCM) mode. VCM provides the opportunity to deliver different services on a Time Division Multiplexing (TDM) basis and in consequence target different reception conditions with a single carrier. This article proposes the combination of the tools provided by DVB-S2X with LDM for satellite broadcast and communication systems. This article describes use cases where multiplexing schemes can be beneficial in comparison with VCM (TDM) approach. The use cases include the delivery of High Definition (HD) and Ultra High Definition (UHD) TV services to customers as well as additional communication services. The performance of the proposal is evaluated with simulations under different channels, including the impact of satellite equipment non-linearities. Analysis shows that LDM provides considerable gain in comparison with VCM in both AWGN and non-linear satellite channels.

A Soft Decoding Algorithm with Hard Decision Boundary Factor for High-Order M-APSK Signal

High-order amplitude phase shift keying is adopted in the latest digital satellite broadcasting system, which presents new challenges to the design of a receiver demodulation scheme. This study focuses on the soft decision decoding algorithm. Traditionally, maximum likelihood soft decision based on log likelihood ratio estimation is often used as a decoding scheme. Accordingly, a soft decision algorithm based on hard decision boundary is designed and the corresponding soft decision estimation formula is derived. Numerical analytical results show that the proposed soft decision algorithm can improve the error performance of a system and substantially reduce the complexity of implementation.

Optimizing the Shape of Faster-Than-Nyquist (FTN) Signals With the Constraint on Energy Concentration in the Occupied Frequency Bandwidth

The achievement of the boundary values of spectral efficiency is associated with the development of methods for generating and receiving signals with a compact spectrum. The reason is a constant increase in the capacity of existing communication channels caused by an increase in the volume of transmitted information. Moreover, the allocated frequency bandwidths have natural limitations, and they are almost all reached. The effective way to approach the boundary values of spectral efficiency is the application of spectrally efficient signals, such as FTN (Faster-Than-Nyquist) signals. This article proposes to synthesize optimal FTN signals that are more compact in the spectrum than RRC (root raised cosine) pulses-based signals. The criterion of maximum energy concentration in the occupied frequency bandwidth and the constraint on the cross-correlation coefficient are used to solve the optimization problem. The contribution of this work is the optimization of FTN signal shape. The obtained optimal FTN signals provide a 24% increase in spectral efficiency compared to the RRC pulses-based signals. At the same time, the energy loss stays almost unchanged. To the best of authors’ knowledge, this is the first case when the frequency bandwidth reduction is achieved at practically no energy loss. The simulation modeling in channels with additive white Gaussian noise and fading channels is done with regard to the FTN-SC-FDE (Faster-Than-Nyquist - Single Carrier system with Frequency Domain Equalization) structure. The optimal FTN signals presented in this work can be used to increase the spectral efficiency of satellite broadcasting systems, such as DVB-S2/S2X.

Displacing Creativity: Artists, Space Scientists and Audience-Led Television in 1970s India

From August 1975 to August 1976 the Indian space agency’s world-leading Satellite Instructional Television Experiment, known as SITE, broadcast to 2,400 villages across the country. This early project of the Indian Space Research Organisation (ISRO) defined a societal remit still considered the formational imaginary behind the space agency’s range of remote sensing and planetary activities. The paper focuses on a brief span of time following SITE when opportunities opened for village residents to take control of the media, and this came about in part through initiatives in which creative practitioners working with the space agency introduced methods of co-production. The shift in creative agency from producers to audiences carried radical possibilities for social mobility and locally determined, rather than state-led, development initiatives. The purpose of this short paper is to highlight how creativity coincided with audience-led innovation. Opportunities for audiences to use the technical equipment opened as creative methods of co-production became more commonplace, such that innovation reflected the cultural values, or cognitive matrix, of the audience. Although the shift in agency from producer to audience was unprecedented, it was swiftly suppressed when the national satellite broadcast system INSAT finally became operational in the 1980s, in spite of—or perhaps because of—this flourish of social innovation. Applying the concept “cognitive innovation” to this context foregrounds the limited opportunities available for rural television audiences to use the technology instrumentally for their own purposes. Displacing creativity, by dismantling the project and putting a halt to its emerging methods of co-production, was a way of delinking the audience from the technology and thereby imposing a different order. By indicating how creative activity accesses cognitive innovation, the paper introduces the notion of “displacing creativity” as a transferable measure of agency. It argues that where creativity is displaced, crucial mechanisms by which subalterns gain agency to act and to innovate are lost.

DVB-S3기반 (1+7)PSK 변조방식에서 FTN 신호의 효율적인 복호 모델

위성방송 시스템의 표준안인 DVB-S3 에서는 LDPC 부호화된 비트를 (1+7) PSK 변조방식과 전송률을 증가 시키기 위해 FTN 기법의 적용 방안을 고려하고 있다. 기존의 복호 방식은 FTN 간섭으로 인한 성능 감소를 위해 BICM-ID 과 BCJR 복호 방식의 반복 복호 기법을 적용하고 있으나, BICM-ID방식은 심볼 LLR 적용후 LDPC 복호기의 출력값을 이용하여 나머지 비트에 대해 복호를 하는 비트 LLR기반인데 이는 많은 계산량을 요구하며, BCJR 복호 방식 또한 순방형 역방향 메트릭을 구하는 과정에서 마놓은 계산량을 요구한다. 따라서 본 논문에서는 FTN 기법의 적용으로 인해 열화된 성능을 반복 복호 기법을 통하여 성능 및 계산량 관점에서 개선하는 효율적인 복호방법을 제안한다. 계산량을 감소시키기 위해 동일 성능향상에서 복호기의 출력 값을 다시 FTN 매핑하여 FTN으로 인한 간섭량을 제거 후 심볼 LLR 계산만 하여 LDPC 복호기로 입력한다. 본 논문에서 제안한 (1+7) PSK 변조방식이 적용된 DVB-S3 시스템에 가우시안 채널에서 성능 향상 및 계산량이 감소됨을 확인 하였다. In DVB-S3 standard of satellite broadcasting systems, FTN technique is applied to LDPC codes with (1+7) PSK modulation. In standard, BICM-ID and BCJR decoding method are considered to alleviate performance degradation due to FTN processing. BICM-ID method improves performance by calculating a new LLR from hard-decision value of decoder output. BCJR also improves performance by calculating forward and backward matrix each other. However these two methods require high computational complexity. Therefore this paper proposed modified decoding method in order to reduce computational complexity without performance degradation.

위성 방송 시스템에서 최적의 고전송 효율 기법 연구

차세대 위성 방송 시스템에서는 빠른 전송 효율과 신뢰도 있는 통신에 대한 요구가 지속적으로 증가하고 있다. 전송 효율을 높이고 성능을 향상시키기 위해 새로운 위성 표준 인 DVB-S3 (Digital Video Broadcasting - Satellite - Third Generation) 시스템에서는 Nyquist 전송률 보다 빠르게 전송하는 FTN (Faster Than Nyquist) 방식이 대두되고 있다. 이러한 요구에 맞춰 본 논문에서는 전송 효율 향상을 위한 세 가지 방식에 대한 성능을 비교 분석하였다. 기존의 LDPC 부호기에서 고 부호화율 방식과 LDPC 복호화 과정에서 생선된 check node를 이용하여 bit node를 puncturing시켜 부호화율 증가 시키는 punctured LDPC 방식, 그리고 Nyquist 속도보다 빠르게 전송하는 FTN 방식이 고려된다. 시뮬레이션을 통해, 세 가지 방식을 동일 전송률 관점에서 성능을 비교한 결과 FTN 방식은 동일한 전송 효율을 유지하면서 성능 면에서 가장 효율적임을 확인하였다. In next generation satellite broadcasting system, requirement of high throughput efficiency has been increasing continuously. To increase throughput efficiency and improve bit error performance simultaneously, FTN method and LDPC codes are employed in new sattelite standard, DVB-S3 system. This paper considered three kinds of methods for increase throughput efficiency. Firstly, as conventional one, high coding rate parity matrix in LDPC encoder is considered. Secondly, punctured coding scheme which delete the coded symbols according to appropriate rules is considered. Lastly, FTN method which transmit fater than Nyquist rate is considered. Among of three kinds of methods, FTN method is most efficient in aspect to performance while maintain same throughput efficiency.