Generation Of Communication Satellites Research Articles

Comparative analysis of types of noise-resistant coding in modems of new generation satellite communication stations

Comparative analysis of types of noise-resistant coding in modems of new generation satellite communication stations

Multi-beam high gain steerable transmitarray lens for satellite communication and 5G mm-Wave systems

This paper presents the design of a high gain multi-beam transmitarray antenna. Designed antenna is capable of independently steering multiple beams in the azimuth and elevation plane by the two dimensional displacement of feed radiators placed in front of the passive meta-surface. The meta-surface acts as an electromagnetic lens. Unit cell of the meta-surface consists of three layers of Rogers 5880 substrate and four layers of etched copper. Unit cell is designed such that the phase of unit cell transmission coefficient is varied from 0° to 360° by changing length of the etched copper pattern. As a proof of concept, meta-surface is designed by using uni-focal phase distribution. Multi-beam steering of 0° to 360° in azimuth plane and 0° to 40° in elevation plane has been achieved. Measured antenna peak gain is 34.2 dBi at 30 GHz. Later on, scan loss was optimized by synthesizing a meta-surface with bi-focal phase distribution. This is a mission enabling technology as the antenna supports seamless hand-off between satellites by forming multiple high gain independently steerable beams. Comparable antennas to the date are low gain, bulky, support limited number of beams, and have limited field of view. To the best of the author’s knowledge, it is first time that high gain multi-beam antenna has been demonstrated by using a passive bi-focal meta-surface for continuous beam steering. Due to absence of active components the designed antenna is low cost and robust. Moreover, the substrate is selected such that the antenna can withstand harsh deep space environment and it can be folded for easy deployment. Due to potentially low fabrication cost and ability to support multiple beams, the proposed antenna is a good candidate for next generation satellite communication and mm-Wave 5G systems.

Orthogonal Versus Zero-Forced Beamforming in Multibeam Antenna Systems: Review and Challenges for Future Wireless Networks

Orthogonality in multibeam antennas is revisited. The difference between orthogonal beamforming and zero-forced beamforming is highlighted. The intriguing relation between orthogonality, reciprocity and losses is recapitulated. Different approaches on the design of orthogonal beamforming networks and implementation of zero-forced beamforming strategies are shown with various examples from the antenna-research-oriented literature. The use of orthogonal and zero-forced beamforming is discussed from the communication system perspective with relevant studies from diverse disciplines. Some of the future research challenges and potential benefits are outlined for the next generation satellite and cellular communication applications.

Massive Access in Space-Based Internet of Things: Challenges, Opportunities, and Future Directions

The integration of fifth generation (5G) mobile network and satellite communication promises a promotion on the interconnection of everything, and has become one of the key development directions of beyond 5G and even 6G. As an inevitable development trend of mobile communication, the space-based Internet of Things (S-IoT) is expected to be commercially available in building an integrated information infrastructure network of the space, air, ground and oceans, and so on. However, the tremendous growth in the number of connected user equipments poses a fundamental rethinking of conventional multiple access technologies, which is considered one of the open challenges in future S-IoT networks. In this article, we first review the main challenges of massive access in S-IoT. Then, we present and discuss how to develop a scalable massive access S–IoT network by leveraging introduced technologies, including intelligent hybrid non-orthogonal multiple access (NOMA) transmission, grant-free superimposed pilot NOMA random access and multi-slot pilot allocation random access protocol. Finally, some exciting future directions of massive access in S-IoT are revealed.

Analysis of Circularly Polarized CTS Arrays

This article presents an efficient analysis method for a novel continuous transverse stub (CTS) antenna. As opposed to state-of-the-art CTS antenna designs, the proposed architecture achieves circular polarization using a single CTS array and without any polarization converter. The structure consists of long radiating slots/stubs fed by over-moded parallel-plate waveguides. More precisely, the transverse electromagnetic (TEM) mode and the first transverse electric (TE1) mode of the feeding waveguides are used to generate a circularly polarized field. The array is analyzed using a spectral mode-matching method. First, the active reflection coefficient of the infinite array is derived in closed form. A windowing approach is then adopted to compute the radiation patterns of finite-size arrays. Numerical results obtained with this method are in excellent agreement with full-wave simulations, carried out with a commercial software. The performance of this class of CTS antennas has been investigated using the developed model. It is theoretically demonstrated that the proposed array can be designed to attain an axial ratio (AR) lower than 3 dB over a 52.9% relative bandwidth at broadside. Furthermore, the active input reflection coefficient is lower than −10 dB over a 40.8% relative bandwidth, when the array steers its main beam at $\theta _{0}=45^\circ $ . This solution is an attractive candidate for next generation satellite communication terminals.

A Flexible Down-Converter for Satellite Communication in the Ka-Band

Abstract Conventional communications satellites operate with fixed frequency, polarisation and coverage plans that are drawn up years before their launch during the payload definition phase. The satellite will typically be designed for a lifetime of more than fifteen years. During this operating period, changes in bandwidth requirements and the distribution of the service across its geographic coverage are more than likely. A new generation of communication satellites is expected to respond flexibly to these regional and temporal fluctuations in demand. The concept of cellular division of the coverage area and the coverage of these cells with spot beams in connection with the reuse of frequency bands enables this flexibility. The satellite's frequency plan has to be redefined throughout the mission lifetime via commands from the ground. The Flexible Down-Converter DOCON is one of the new components that allow satellite signals to be redistributed between service areas to flexibly reallocate the most critical spectrum resources as needed. DOCON is a flexible Ka-band down-converter from RF = 27.5 ... 30.0 GHz to IF = 17.7 ... 20.2 GHz designed for GEO communication satellites. The device includes the housing, DC-, RF-, and telemetry / tele-command interfaces. An Engineering Model (EM) in form, fit and function was successfully built and tested. The next stage, the Engineering Qualification Model (EQM), is currently in fabrication and will be qualified until end of 2019. The modular concept comprises hermetically sealed LTCC microwave modules as key building blocks. There are three of these LTCC-modules: the Local Oscillator Module (LOM), the Mixer Module (MXM), and the Variable Gain Module (VGM). Their function and realization shall be discussed in this paper.

Performance analysis of interleaved LDPC for optical satellite communications

Optical wireless communications using a laser is a strong candidate for the next generation satellite communications due to its large bandwidth. However, the channel environment of satellite communications is very tough, suffering from fading by atmospheric turbulence. Therefore, an efficient channel coding such as low-density parity check (LDPC) coding is required to satisfy stable transmission. In this paper, fading noise from atmospheric turbulence is reproduced to simulate the satellite channel. Then, this time-varying signal is used to evaluate the performance of the LDPC codes in different channel environments. At the same time, in order to improve the system performance further, an interleaving method in combination with LDPC codes is proposed to overcome the problem of burst error, which frequently occurs in the optical satellite communication systems (OSC). Simulation results show that the block-interleaving scheme can achieve a 5 dB gain compared to the pure LDPC scheme. The processing time is considered to determine the proper size of interleaving blocks suitable for optical satellite communications.

A new CubeSat design with reconfigurable multi-band radios for dynamic spectrum satellite communication networks

Small satellites, or CubeSats, are envisioned as a promising solution for future satellite communication networks because of their low costs and short deployment cycle. Currently, CubeSats communicate at conventionally allocated satellite communication frequencies. However, with the increase in the number of CubeSats, CubeSat-enabled communication systems, and many new use cases, new spectrum bands and a more efficient spectrum usage are needed. In this paper, a novel CubeSat design with reconfigurable multi-band radios for communication in dynamic frequencies is proposed.The multi-band radio design is realized by two complementary approaches, namely, an electronics-based and a photonics-based approach. The multi-band communication covers a wide range from radio frequencies (2–30 GHz), millimeter wave (30–300 GHz), Terahertz band (up to 10 THz), and optical frequencies (with typical bands of 850 nm/350 THz, 1300 nm/230 THz, and 1550 nm/193 THz). A thorough link budget analysis is conducted to demonstrate the potential of the proposed multi-band architecture for space information networks. Key parameters in the satellite constellation design are investigated to explore the feasibility of deployment at different altitudes in the exosphere orbit (500 km and above). A continuous global coverage is demonstrated to serve the Internet of Space Things, a new paradigm for next generation satellite communication networks.

Framework for Unifying 5G and Next Generation Satellite Communications

5G systems have started field trials, and deployment plans are being formulated, following completion of comprehensive standardization efforts and the introduction of multiple technological innovations for improving data rates and latency. Similar to earlier terrestrial wireless technologies, build-out of 5G systems will occur initially in higher population density areas offering the best business cases while not fully addressing airborne and marine applications. Satellite communications will thus continue to be indispensable as part of an integrated 5G/satellite architecture to achieve truly universal coverage. Such a unified architecture across terrestrial and satellite wireless technologies can ensure global service, support innovative 5G use cases, and reduce both capital investments and operational costs through efficiencies in network infrastructure deployment and spectrum utilization. This article presents an architectural framework based on a layered approach comprising network, data link, and physical layers together with a multimode user terminal. The network layer uses off-the-shelf building blocks based on 4G and 5G industry standards. The data link layer benefits from dynamic sharing of resources across multiple systems, enabled by intersystem knowledge of estimated and actual traffic demands, RF situational awareness, and resource availability. Communication resource sharing has traditionally comprised time, frequency, and power dimensions. Sharing can be enhanced by leveraging dynamic knowledge of communication platform location, trajectory, and antenna directivity. Logically centralized resource management provides a scalable approach for better utilization of spectrum, especially in higher bands that have traditionally been used by satellites and now are also being proposed for 5G systems. Resource sharing maximizes the utility of a multimode terminal that can access satellite or terrestrial RF links based on specific use cases, traffic demand, and QoS requirements.

High-throughput satellite (HTS) with radio and optical frequencies for the next generation satellite communications

High-throughput satellite (HTS) with radio and optical frequencies for the next generation satellite communications

High throughput satellites in 5G and MIMO interference limited communications

Classically, thermal noise has been the workhorse of satellite communications due to the long distances to be covered between the satellite and the user terminal (UT). Lately, LDPC (Low-Density Parity-Check) codes allow the noise threshold to be set very close to the Shannon limit for the memory-less satellite channel; thus, solving the noise problem that turbo codes were not able to solve. However, recently, the high target rates in next generation 5G wireless terrestrial system are pushing the required spectral efficiency in Satellite Communications; therefore, shifting the SatCom paradigm towards an interference limited one. This paper revisits the 5G scene and the role of next generation satellite communications, with a special focus on high throughput satellites (HTS) together with the future accompanying MIMO interference mitigation techniques.

Mobile health: new technologies, new modes and new era.

Mobile health: new technologies, new modes and new era.

Ka band enabling technologies for high throughput satellite (HTS) communications

AbstractGlobal demands for personal, businesses and governments connected data continue to challenge our communication technologies and infrastructure. Both wired and wireless terrestrial communications systems are realizing advancements in technologies and their applied infrastructure enhancements. These ever evolving terrestrial communication systems are providing for increased data capacity, an enhanced quality of service and a lower cost per bit for all users. Satellite systems are especially challenged in order to remain relevant for these same enhancements in order to augment and compete with these terrestrial global communication systems. In order to meet these global demands the next generation satellite communications systems are evolving by advancing their own technologies and infrastructure. The resulting next generation communication satellite systems include utilization of the Ka frequency band and also through the application of other key advancements in antenna systems and processing payloads. This paper provides an overview of many of the communication satellite system advancements which are in part enabled through the utilization of the Ka frequency band. Copyright © 2015 John Wiley & Sons, Ltd.

Dual Polarized Modulation and Reception for Next Generation Satellite Communications

Dual Polarized Modulation and Reception for Next Generation Satellite Communications

차기 군 위성통신체계 환경에서 이동형 위성단말의 채널 blockage 극복을 위한 확산기반 협업통신 기법의 성능 분석

본 논문에서는 차기 군 위성통신체계 환경에서 OTM(On-The-Move) 위성단말의 채널 blockage 신호 손실 보상을 위한 협업통신 기법을 제안하였다. 제안하는 협업기법은 인접 OTM 위성단말과 지상 무전기 체계를 통해 데이터를 공유하고 직교확산코드를 이용하여 대역확산 후 동시에 전송한다. 중첩되어 전송된 확산열은 EGC(Equal Gain Combining) 방식으로 결합한다. 성능 분석을 위해 OTM 위성단말의 blockage 채널을 2-state Markov chain으로 모델링하였으며, 이를 기반으로 협업단말들의 blockage 채널 상태에 따른 비트오류율을 도출하였다. 성능분석 결과 채널 조건이 더 나은 인접 OTM 위성단말의 협업으로 비트오류율 성능이 향상됨을 확인할 수 있었다. 특히 blockage 확률이 높을수록 협업을 통해 더욱 우수한 성능을 확인할 수 있었다. 그러나 서로 다른 지연을 갖는 확산 열 간 중첩으로 인해 협업단말 수 증가 시 다중접속간섭으로 인한 성능상의 제약이 있음을 확인하였다. To compensate signal loss due to the channel blockage in satellite communication link, we propose a cooperative communication scheme for OTM(On-The-Move) terminal in next generation satellite communication systems. The proposed scheme configures cooperation subnet with adjacent OTM terminal with the help of ground communication equipment. Shared data is spread by orthogonal spreading code, then the spread sequences are transmitted simultaneously. The receiver combines the power of received signals by EGC(Equal gain combining). The OTM terminal blockage channel is modeled by 2-state Markov chain. We evaluate the bit error rate according to the blockage channel of the channel state for the performance analysis of the proposed scheme. As a result, the proposed scheme shows better BER performance than traditional scheme with the help of subset members. In particular, the proposed scheme shows superior performance as the channel block probability is higher. However, as the number of subset members is increasing, there is a constraint because of the higher multiple access interference.

위성 통신 환경에 적합한 분산 망관리시스템을 위한 DDS의 성능 분석

차기 위성의 통신망은 단말의 수가 증가하고 네트워크의 구조가 분산화 및 대형화되고 있는 추세이며, 위성 통신을 이용하는 트래픽이 증가하고 빈번하게 발생하고 있다. 위성 통신과 같이 다양한 통신 장비들이 동적으로 도메인을 형성하고 데이터를 빈번하게 주고받는 통신 환경에서는 서버/클라이언트 방식의 데이터 교환보다는 데이터 중심 발간/구독 방식의 데이터 교환이 더욱 효과적이다. 따라서 본 논문에서는 한정된 위성 자원을 효율적으로 관리하기 위한 분산 망관리시스템에 데이터 중심 발간/구독 통신 기술인 DDS 표준을 적용하기 위하여 DDS의 성능을 분석하였으며, 기존의 서버/클라이언트 방식으로 데이터를 교환하는 SNMP와 비교 연구하였다. 비교 연구를 위해 OPNET을 사용하였으며 네트워크 계층 관점의 성능 중심으로 수행하였다. Trend of next generation satellite communication network is distribution and enlargement of network structure with increased network terminals, and traffic which use satellite communication is increasing and frequently occurring. Under specific satellite communication environment that various communication device dynamically forms a network domain and frequently exchanges the data, data-centric publish/subscribe data exchange is more suitable than server/client data exchange. So, this paper analyze DDS performance for application of DDS standard to distribution network management system which aims to efficiently manage limited satellite resource, and also this paper covers comparative study on DDS and SNMP(server/client data exchange). Study compares DDS and SNMP using OPNET, and result of study is analyzed from a network layer performance perspective.

Communication satellites to enter a new age of flexibility

To cope with the economical and technical evolutions of the communication market and to better compete with or complement terrestrial networks, satellite operators are requiring more flexible satellites. It allows a better fleet planning potential and back-up policy, a more standardized and efficient procurement process, mission adaptation to market evolution and the possibility of early entry in new markets. New technologies that are developed either for terrestrial networks or for space defense applications would become soon available to satellite and equipment manufacturers. A skilful mix of these new technologies with the older and more mature ones should boost satellite performances and bring flexibility to the new generation of communication satellites. This paper reviews the economical and technical environment of the space communication business for the next decade. It identifies the needs and levels of flexibility that are required by the market but also allowed by technologies, in both a top-down and bottom-up approach.

Broadband and scalable mobile satellite communication system for future access networks

Due to the recent market trends, NTT has begun research into next generation satellite communication systems, such as broadband and scalable mobile communication systems. One service application objective is to provide broadband Internet access for transportation systems, temporal broadband access networks and telemetries to remote areas. While these are niche markets the total amount of capacity should be significant. We set a 1-Gb/s total transmission capacity as our goal. Our key concern is the system cost, which means that the system should be unified system with diversified services and not tailored for each application. As satellites account for a large portion of the total system cost, we set the target satellite size as a small, one-ton class dry mass with a 2-kW class payload power. In addition to the payload power and weight, the mobile satellite's frequency band is extremely limited. Therefore, we need to develop innovative technologies that will reduce the weight and maximize spectrum and power efficiency. Another challenge is the need for the system to handle up to 50 dB and a wide data rate range of other applications. This paper describes the key communication system technologies; the frequency reuse strategy, multiplexing scheme, resource allocation scheme, and QoS management algorithm to ensure excellent spectrum efficiency and support a variety of services and quality requirements in the mobile environment.

SES Americom Maximizes Satellite Revenues by Optimally Configuring Transponders

SES Americom Inc. will launch AMC-12, the first of its new generation of communication satellites, in early 2004. This satellite has 24 highly sophisticated transponders, each of which can serve up to three markets simultaneously. By changing the configuration of the transponders, we can alter the markets they serve, thereby adjusting the capacity available by market. We developed a pricing- and contract-management system to maximize the revenues that AMC-12 generates. The system tracks signed contracts and projected demands over the life of the satellite, and recommends optimal configurations for the satellite's 24 transponders each month to maximize revenues. We modeled the transponder-configuration problem as a mixed-integer program and developed efficient heuristics for solving the problem. We implemented our algorithms in a Microsoft Excel-based system with a Visual Basic user interface. SES Americom is using the system to manage over $2 billion in revenues. We plan to adapt the system for use in other satellites with similar technology to be launched in the future.

Solar Array Simulators for INSAT-2E/3B

Considering that a spacecraft cannot be accessed after launch and it is subjected to harsh environmental conditions during launch such as shock, vibration, acoustics in addition to vacuum, large temperature variation during orbit; the design of various subsystems must take into account both the short and long term effects of this environment and ground testing must establish that the quality and reliability of the spacecraft is acceptable through out its long life mission. The integrated spacecraft testing must ensure that all various subsystems and their respective interfaces are performing satisfactorily and working in unison as a single system during all phases of Assembly, Integration and Testing including environmental testing. The main source of power is Solar Panels and the size of these increase with increasing power requirements. Taking into account the size and fragility of the solar panels, normally they are integrated at the last. Therefore, during all ground tests, the major challenge faced is in feeding power to the spacecraft, yet under real conditions. Electronic Solar Array Simulator, an inexpensive, flexible and well protected custom made power supply offers the solution. This can simulate quickly and accurately the true V-l characteristics of solar panels under varying conditions. This paper describes the Solar Array Simulator, designed and developed at ISRO Satellite Centre (ISAC) for new generation of communication satellites which were successfully used during all phases of testing for INSAT-2E and INSAT-3B spacecrafts and also are to be employed for all our future spacecrafts testing.