New Multicarrier Modulation for Satellite-Ground Transmission in Space Information Networks

Multicarrier modulation (MCM) schemes have been intensively studied and developed, because of their numerous advantages, which include high data rate and immunity to multipath fading. Among MCM schemes, filter bank multicarrier with offset quadrature amplitude modulation (FBMC-OQAM) has attracted considerable interest in recent years. However, the FBMC-OQAM system exhibits a high peak-to-average power ratio (PAPR). In this paper, we investigate the FBMC-OQAM system and present a solution for the problem of high PAPR that involves two separate components: minimizing the PAPR of each data block and optimizing each segment based on the preceding result. Unlike conventional partial transmit sequence techniques, the new method uses fewer combinations of phase factors, thereby decreasing the complexity of the algorithm while still reducing PAPR. In addition, sparse clipping signals are recovered by compressed sensing, and the bit error rates were analyzed based on sparsity level. The reductions in PAPR were also numerically evaluated using simulations. The simulation results confirm that the proposed technique effectively reduces the high peaks in the FBMC-OQAM system.

The ripple modulation (RM) is a technique that provides a variable output voltage by using the output voltage ripple of a switching-mode power converter. It was proposed to reproduce the communication signal of a visible light communication transmitter, thus avoiding the use of power inefficient linear power amplifiers. However, the RM has a major drawback: it has not been reported how to reproduce multicarrier modulation (MCM) schemes, which are the preferred modulation schemes due to their high performance in wireless communications. In this paper, it is demonstrated that the RM can be used to reproduce MCM schemes by considering the envelope and the instantaneous phase of the communication signal. Moreover, the control system of the power stage is described in detail, explaining how to modulate both the width and the phase of the gate signals, the calculation of the phase shift that is required for tracking the envelope, etc.

SIN (Space Information Network) is expected to play an increasing role in providing real-time, flexible, and integrated communication and data transmission services in an efficient manner. Nowadays, SIN has been widely developed for position navigation, environment monitor, traffic management, counter-terrorism, etc. However, security is a major concern in SIN, since the satellites, spacecrafts, and aircrafts are susceptible to a variety of traditional/specific network-based attacks, including eavesdropping, session hijacking, and illegal accessing. The network architecture and security issues of SIN were reviewed. Various security requirements were discussed that should be considered when designing SIN. And existing solutions proposed to meet these requirements were surveyed. The key challenges and key technologies that still require extensive research and development for securing SIN were indentifed.

A steadily growing number of Internet-based service requests from the IoT have led to an increase in complexity and clients, resulting in an increased number of cybersecurity concerns. Although there are main security concerns with IoT services over cloud computing services, cloud computing is mostly preferred to provide seamless and scalable Intern-based services. Moreover, cloud service providers are continuously extending their capacity to reach more industries and address their concerns. For example, Amazon has recently launched a pay-as-you-go cloud computing service that will take place on satellite operators to provide more IoT services to industries such as the agricultural and shipping industries. However, the secure transfer of information within a space information network is of great concern due to numerous attacks between nodes to occur. This can be followed by loss of data Confidentiality, Integrity, and Availability. Several researchers have proposed multifaceted solutions to these concerns, including blockchain application, digital signature, symmetric/asymmetric encryption schemes, and centralized and/or decentralized key management for space information networks. In this paper, we focus on the integration of fog-cloud computing and space information network. We primarily investigate the feasibility of fog-cloud architecture in space information networks and the benefits of having fog computing in space information networks' security. This is accomplished mainly by reviewing existing works on fog-cloud computing and space information networks and evaluating both proposed solutions to potential issues regarding security.

Filter Bank Multicarrier and Generalized Frequency Division Multiplexing are being considered as the major candidates for the 5G modulation schemes. Orthogonal Frequency Division Multiplexing is used in 4G but owing to its Out of Band spectral leakage it is being replaced by these modified waveforms. Multicarrier Modulation schemes are sensitive to Carrier Frequency Offset which significantly degrades the Signal to Noise Ratio by introducing Inter Carrier Interference causing degradation in the Bit Error Rate performance. This paper provides an in-depth investigation and analysis on the effects of Carrier Frequency Offset on the performance of Filter Bank Multicarrier and Generalized Frequency Division Multiplexing under AWGN and fading environments. Results are compared with the Orthogonal Frequency Division Multiplexing to highlight the features of either modulation scheme under various static and dynamic environments.

We propose a FFT-based universal filtered multicarrier (UFMC) modulation scheme used for datacenter interconnect to support low overhead and agile transmission. The feasibility of this proposed UFMC scheme is experimentally investigated in the IM/DD system. The results have shown that, the UFMC-based datacenter interconnect can achieve great system overhead reduction and support different subband width division rules, which can be well suitable for the agile optical transmission of datacenter interconnect. Moreover, UFMC-based interconnect system is demonstrated to enhance the timing offset tolerance compared to CP-OFDM, which can further improve the system transmission performance.

Terahertz (THz)-band (0.1-10 THz) communication has been envisioned as a key technology to enable wireless Terabit-per-second (Tbps) links. At THz frequencies, the path-loss is governed by the spreading loss and the molecular absorption loss. The latter also determines the available transmission bandwidth, which drastically shrinks with distance. As a result, traditional modulation schemes cannot fully take advantage the THz channel, and new modulation schemes are needed if THz channel communications are going to reach their full potential. Several solutions have been presented including Hierarchical Bandwidth Modulations (HBM), which is the only presented work that not only compensates for molecular absorption losses but leverages those losses to improve the capabilities of the system. The focus of this thesis is two-fold. First the design of HBM is formalized, exploring the trade-offs and achievable performance as a function of system parameters. Secondly, these trade-offs and performance metrics are verified using a one-of-a-kind experimental testbed for ultrabroadband communication networks. The results show that with proper design HBM successfully achieves its goal of exploiting the distance-dependent characteristics of the THz channel.--Author's abstract

SIN (Space Information Network) has recently emerged as a promising approach to solving the collaboration difficulty among current space programs. However, because of the SIN’s large scale, high component complexity, and dynamic characteristics, designing a proper SIN architecture is challenging. Firstly, we propose a novel SIN architecture, which is composed of GEO (Geostationary Earth Orbit) satellites as backbone network nodes, LEO (Low Earth Orbit) or other types of satellites as enhanced coverage nodes, and high-altitude platforms to meet the service requirements of emergency or hotspot applications. Unlike most existing studies, the proposed architecture is AS (Autonomous-System) based. We decouple the complex SIN into simpler sub-networks using a hierarchical AS model. Then, we propose a topology control algorithm to minimize the time delay among sub-AS networks. We prove that the proposed algorithm achieves logical k-connectivity provided that the original physical topology has k-connectivity. Simulation results validate the theoretic analysis and effectiveness of the algorithm.

Multicarrier modulation schemes are widely used in several digital telecommunication systems, such as Asymmetric Digital Subscriber Lines (ADSL) and Wireless Local Area Network (WLAN) based on Orthogonal Frequency Domain Multiplexing (OFDM). An estimate of the Bit-Error-Rate (BER) degradation due to non-idealities in the transceiver (e.g. nonlinear distortions in the analog front-ends, digital clipping,...) is much more complicated in a multicarrier system than in a single-carrier system due to the large number of carriers and the huge number of possible transmitted symbols. This paper proposes a method for estimating the BER of such OFDM modulation schemes in a CPU time that is two orders of magnitude smaller than a Monte-Carlo method, as confirmed by simulations on a 5 GHz IEEE 802.11 WLAN receiver front-end.

Multicarrier modulation schemes are widely used in several digital telecommunication systems, such as Asymmetric Digital Subscriber Lines (ADSL) and Wireless Local Area Network (WLAN) based on Orthogonal Frequency Domain Multiplexing (OFDM). An estimate of the Bit-Error-Rate (BER) degradation due to non-idealities in the transceiver (e.g. nonlinear distortions in the analog front-ends, digital clipping,...) is much more complicated in a multicarrier system than in a single-carrier system due to the large number of carriers and the huge number of possible transmitted symbols. This paper proposes a method for estimating the BER of such OFDM modulation schemes in a CPU time that is two orders of magnitude smaller than a Monte-Carlo method, as confirmed by simulations on a 5 GHz IEEE 802.11 WLAN receiver front-end.

Wireless communication has a very important role in the day to day life for everyone. The wireless technology is growing rapidly and there is a growing demand of high performance, capacity and larger bit rate wireless communication systems which cope wireless communication services such as high speed data, video and voice signals. Multicarrier modulation scheme like OFDM provides an efficient solution to overcome this problem. In this paper a gray scale image processing is done using a LMS algorithm with wavelet based OFDM system using the QPSK modulation scheme in AWGN and Rayleigh channel in SISO environment and results are compared with the conventional adaptive FFT based OFDM system. We reconstruct our transmitted signal at receiver; in both systems by minimizing the error by adaptive filter but the computational complexity of FFT based system is more as compared to DWT based system. Results are compared in term of SNR vs BER which shows that adaptive DWT based OFDM system perform better as compared to the conventional adaptive FFT OFDM system.

Orthogonally multiplexed Quadrature Amplitude Modulation (OQAM) with Filter-Bank-based MultiCarrier modulation (FBMC) is a multicarrier modulation scheme that can be considered an alternative to the conventional orthogonal frequency division multiplexing (OFDM) with cyclic prefix (CP) for transmission over multipath fading channels. However, as OQAM-based FBMC is based on real orthogonality, transmission over a complex-valued channel makes the decoding process more challenging compared to CP-OFDM case. Moreover, if we apply Multiple Input Multiple Output (MIMO) techniques to OQAM-based FBMC, the decoding schemes are different from the ones used in CP-OFDM. In this paper, we consider the combination of OQAM-based FBMC with single-delay Space-Time Trellis Coding (STTC). We extend the decoding process presented earlier in the case of Nt = 2 transmit antennas to greater values of Nt. Then, for Nt ≥ 2, we make an analysis of the theoretical and simulation performance of ML and Viterbi decoding. Finally, to improve the performance of this method, we suggest an iterative decoding method. We show that the OQAM-based FBMC iterative decoding scheme can slightly outperform CP-OFDM.

Multi-Carrier (MC) modulation schemes like Orthogonal Frequency Division Multiplexing (OFDM) are highly sensitive to Phase Noise (PN). In the case of air interfaces operating in higher frequencies, e.g. the range between 6 and 100 GHz frequently called millimeter wave (mmWave), the PN generated by the local oscillators is even more accentuated. Alternative MC systems are being considered for future mmWave wireless communications. In this contribution, we analytically derive expressions for an upper bound for the interference power generated by the PN in OFDM, DFT-Spread-OFDM and Filter Bank Multi-Carrier (FBMC). Then, we evaluate the performance degradation due to that imperfection in terms of coded and uncoded BER.

Multi-carrier modulation (MCM) schemes have been under developed as an effective way to improve channel capacity utilization under multipath interference and selective fading reception for next generation two-way wireless communication systems. However, in the application of one-way broadcasting there is a great need for a new system that cannot only operate in a multipath environment, but also can reuse scarce spectral resources and employ cost-effective high-power amplifiers. For this research, an MCM system referred to as multi-carrier code division multiple access (MC-CDMA) was developed to characterize the primary broadcasting concern of operating under high power amplifier (HPA) nonlinearities. We cover MC-CDMA background, its application to broadcasting, the expected performance limits, and modeling approach.

The significance of digital communication has been well accepted all over the world. It has been widely used in wireless networks like satellite communication, and 4G and 5G technologies as it provides high data connectivity and efficiency. For long-distance transmission and reception of signals, maintaining the signal quality is very important and therefore an efficient modulation and demodulation scheme is required. In this paper, the quadrature phase shift keying (QPSK) modulation scheme is being presented. Its several advantages over other digital modulation techniques made it one of the best forms of digital modulation. The concept of software-defined radio has been used as a test bed for implementing QPSK modulation. Simulation of QPSK modulation and demodulation process is performed in Laboratory Virtual Instrument Engineering Workbench software, and the digital transmission and reception of signals are done through Universal Software Radio Peripheral. The signal experiences sampling, quantization, filtering, encoding, modulation, demodulation, decoding, with and without the addition of additive white Gaussian noise on the graphical interface of NI LabVIEW. Several investigations have been done on digital modulation, but they are covered entirely on simulation in any software. In this paper along with the implementation of modulation and demodulation part, the transmission and reception of the signal are also performed using USRP.