Channel Bit Research Articles

Long wavelength fluoride optical glass fibers performance signature in high speed local area data networks

Abstract This paper has clarified long wavelength fluoride optical glass fibers performance signature in high speed local area data networks. The signal attenuation and the total fiber pulse broadening are studied versus network length for various fluoride optical glass fibers and AS2 Se3 glass fiber at various spectral wavelengths. The total signal delay time is demonstrated with fiber numerical aperture with 15 km network length for various fluoride optical glass fibers and AS2 Se3 glass fiber at 2.5 μm optimum spectral wavelength. Total fiber signal bandwidth, total Shannon channel bit rate, and NRZ/RZ channel data rate transmission are clarified with 15 km network length for various fluoride optical glass fibers and AS2 Se3 glass fiber at 2.5 μm optimum spectral wavelength.

An Analog MP3 Compression Psychoacoustic Model Implemented on a Field-Programmable Analog Array

This effort describes a low-power analog MP3 psychoacoustic model designed, implemented, and demonstrated using a large-scale Field-Programmable Analog Array (FPAA) to allocate bits for MP3 compression. Although MP3 encoders are assumed to be a digital algorithm, this effort looks to create analog algorithm versions. This block could enable low-power real-time MP3 encoding of microphone input signals for higher-quality acoustic transmissions, significantly improving the audio quality of the compressed transmitted signal from battery-powered devices. An exponentially spaced filterbank enables a low-power representation consistent with human hearing transduction. An analog psychoacoustic model uses signal masking to determine channel bit rates. These designs would enable a fully integrated MP3 encoder when implementing the straightforward aspects of the MDCT.

Various graded index plastic optical fiber performance signature capability with the optimum dispersion control for indoor coverage applications

Abstract This work has clarified the various graded index plastic optical fiber performance signature with the optimum dispersion control for indoor coverage applications. The plastic optical fibers that are deeply employed namely Polymethyl mathacrylate (PMMA), Epoxy, Polyfluorene and Cyclotene. Various plastic optical fiber dispersion is demonstrated against temperature variations. The different plastic fibers pulse broadening is clarified versus temperature variations. The previous plastic optical fibers types with respect to refractive index configuration and number of modes are clarified. Previous studies on PMMA/CYTOP plastic optical fibers attenuation is clarified against wavelength band variations. Various transmission techniques are applied to measure the fiber bandwidth and fiber channel bit rate. These transmission techniques are MTDM, NRZ and RZ coding. Different plastic fiber bandwidth against fiber channel distance is demonstrated based on NRZ, RZ and MTDM coding at room temperature. Different plastic fiber channel bit rate against fiber channel distance is studied and clarified based on NRZ, RZ and MTDM coding at room temperature. The choice of these plastic fibers are high temperature stability and more flexibility/reliability than other plastic fibers. The dispersion of these proposed plastic fibers can be controlled and managed with the control of temperature variations.

Optimization of Signal Detection Using Deep CNN in Ultra-Massive MIMO

This paper addresses the evolving landscape of communication technology, emphasizing the pivotal role of 5G and the emerging 6G networks in accommodating the increasing demand for high-speed and accurate data transmission. We delve into the advancements in 5G technology, particularly the implementation of millimeter wave (mmWave) frequencies ranging from 30 to 300 GHz. These advancements are instrumental in enhancing applications requiring massive data transmission and reception, facilitated by massive MIMO (multiple input multiple output) systems. Looking towards the future, this paper forecasts the necessity for faster data transmission technologies, shifting the focus toward the development of 6G networks. These future networks are projected to employ ultra-massive MIMO systems in the terahertz band, operating within 0.1–10 THz frequency ranges. A significant part of our research is dedicated to exploring advanced signal detection techniques, helping to mitigate the impact of interference and improve accuracy in data transmission and enabling more efficient communication, even in environments with high levels of noise, and including zero forcing (ZF) and minimum mean square error (MMSE) methods, which form the cornerstone of our proposed approach. Additionally, signal detection contributes to the development of new communication technologies such as 5G and 6G, which require a high data transmission efficiency and rapid response speeds. The core contribution of this study lies in the application of deep learning to signal detection in ultra-massive MIMO systems, a critical component of 6G technology. We compare this approach with existing ELMx-based machine learning methods, focusing on algorithmic efficiency and computational performance. Our comparative analysis included the regularized extreme learning machine (RELM) and the outlier robust extreme learning machine (ORELM), juxtaposed with ZF and MMSE methods. Simulation results indicated the superiority of our convolutional neural network for signal detection (CNN-SD) over the traditional ELMx-based, ZF, and MMSE methods, particularly in terms of channel capacity and bit error rate. Furthermore, we demonstrate the computational efficiency and reduced complexity of the CNN-SD method, underscoring its suitability for future expansive MIMO systems.

Non-orthogonal pilot pattern design and sparse channel estimation for underwater acoustic MIMO-OFDM systems

This paper proposes a novel non-orthogonal pilot pattern design method for underwater acoustic (UWA) multiple-input-multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) systems, leveraging compressive sensing (CS) channel estimation. This approach adopts the mutual incoherence property (MIP) and enhances pilot density without increasing pilot overhead. We conducted rigorous mathematical derivation to generate the explicit formula for the non-orthogonal pilot pattern with the mutual coherence of zero. In addition, we estimate multipath delay and amplitude by employing parallel orthogonal matching pursuit (OMP) channel estimation. The co-channel interference (CCI) is eliminated from the systems with the proposed non-orthogonal pilot pattern to estimate the channel coefficients from two transmitters without interference in a single iteration. Simulations and lake trial results demonstrate the superior performance of the proposed non-orthogonal pilot pattern over the orthogonal and existing non-orthogonal pilot patterns in terms of normalized mean square error (NMSE) of channel estimation and bit error rate (BER). The 2×8 UWA MIMO-OFDM system achieves a data rate of 78.11 kbps with a BER of 1.42×10−4 in the lake trial over the communication distance of 773 m.

Adaptive refined random orthogonal matching pursuit algorithm for FBMC/OQAM MIMO framework

The fifth generation of wireless communication is anticipated to provide improved quality of service and enhanced data rates to the end users. One such technology that stands out as a potential transmission scheme for 5G systems is Filter Bank Multicarrier using Offset Quadrature Amplitude Modulation (FBMC/OQAM) with an effective channel estimation technique for improved performance. However, due to the inherent imaginary interference, channel estimation methods relying on preamble structures in FBMC/OQAM systems exhibit sub-optimal performance, particularly within Multiple-Input Multiple-Output (MIMO) setups. For channel estimation schemes based on compressed sensing, the inherent sparsity of wireless channels can be exploited for accurate channel reconstruction and overall performance improvement.We propose a novel compressed sensing based algorithm namely, Adaptive Refined Random Orthogonal Matching Pursuit (ARROMP), for MIMO-FBMC system with Coordinated MultiPoint (CoMP) scheduling. This algorithm adaptively selects a support set by utilizing a double threshold for the minimization of mean squared error and for accurate channel reconstruction. The proposed algorithm's performance is compared with existing Orthogonal Matching Pursuit (OMP) schemes such as random OMP, refined random OMP, and least square-based estimation. The numerical simulations suggest that the proposed adaptive algorithm provides performance improvement in terms of reduced Mean Squared Error (MSE) of channel reconstruction and Bit Error Rate (BER). Moreover, the proposed ARROMP algorithm for MIMO-FBMC is rigorously tested with CoMP scheduling for a cellular network using frequency division duplex mode. The proposed system presents significant improvements in throughput and spectral efficiency for all types of cell users, including cell-edge users. The simulation results validate the improved performance of the proposed algorithm with CoMP scheduling over the existing single-cell system with no coordination.

Метод кадрової синхронізації на основі кортежів попарно відмінних елементів

The further development of the frame synchronization method is presented, which uses as a synchronization word the permutation of the elements of the set of integers of the segment [0; M  1], was further developed. It is proposed to use a tuple of M-η pairwise distinct elements of the set of integers of the segment [0; M 1] as a syncword. The elements of this set are encoded with a fixed-length binary code and the minimum binary Hamming distance between the syncword and all its circular shifts is the maximum. The paper established that the maximum value of the minimum Hamming distance for tuples of 15 pairwise distinct elements of the set of integers for M = 16 is equal to 30. A comparative assessment of the frame synchronization effectiveness was performed based on tuples of 15 elements, as well as on permutations of length 16 and 8. A computer simulation model of the frame synchronization system in a binary symmetric communication channel was built. Synchronization indicators were determined with parameters calculated for bit error probability 0,4 and 0,495, as well as requirements for a min-imum probability of correct synchronization of 0,9997 and a maximum probability of false synchronization of 3E-4. The effectiveness of using tuples of pairwise distinct elements in frame synchronization systems has been confirmed. The efficiency indicator depends on com-munication channel bit error probability.

A Survey of Localization Techniques for Underwater Wireless Sensor Networks

With the continuous development of marine resources, the position of Underwater Wireless Sensor Network (UWSN) is becoming more and more important, and UWSN needs to know the location of sensor nodes when completing tasks such as marine data collection, environmental monitoring, and aiding navigation, etc. Accurate sensor node location information is the key to effective acquisition of underwater data. The key to effective underwater data acquisition is accurate sensor node location information. Due to the influence of the environment, global positioning system (GPS) signals cannot be propagated underwater, so hydroacoustic communication becomes the best choice for node positioning. However, the unstable underwater environment brings a series of challenges to hydroacoustic communication, such as high channel bit error rate, low bandwidth, large propagation delay, and obvious multipath effect. According to the characteristics and challenges of hydroacoustic communication, this paper classifies the localization algorithms of underwater wireless sensor networks into (i) distance-based and distance-free localization algorithms, (ii) single-hop and multi-hop localization algorithms, and (iii) distributed and centralized localization algorithms.

Modeling of Satellite-to-Underwater Integrated FSO-PON System Using NOMA-VLC

In recent years, optical wireless communication has promised several benefits over radio frequency communication in atmospheric, deep space and underwater communications. Satellite-to-underwater communication technology can be applied to commercial, naval, scientific and engineering operations because of its high data rate, high security, long-reach and low cost. In this paper, a high-speed, long-reach integrated free space optics (FSO)-passive optical network (PON) system using non-orthogonal multiple access visible light communication (NOMA-VLC) is proposed. It poses a 10/2.5 Gbps per channel bit rate for satellite-to-underwater applications. Numerically calculated results provide the splitter power budget of −35 dBm in the downlink and −32 dBm in the uplink. Additionally, a receiver sensitivity of 23 dB in the downlink and 10 dB in the uplink direction can be obtained in the system using a modified new zero cross-correlation (MNZCC) code under clear environment conditions. Again, the simulative analyses indicate that the suggested system supports 290 underwater devices successfully and offers a high 10 dBm signal-to-noise ratio over 10 km FSO, 100 km fiber and 5 m VLC range. Moreover, it provides a signal-to-noise ratio of 39 dB, with −9 dBm received optical power at 300 fields of view under fiber-wireless channels’ impairments. We argue that the suggested system is a symmetric system adapted to different link distances and which offers improved receiver sensitivity and high received optical power at a 10−9 bit error rate (BER). The comparative analysis shows the advantages of the suggested system over previously reported works.

Залежність ефективності кадрової синхронізації нероздільних факторіальних кодів від параметрів синхронізації

This paper aims at implementing the principles of establishing frame synchronism for non-separable factorial codes, as well as applying the operation of interleaving fragments received from the communication channel to increase the efficiency of finding permutation boundaries. We apply the algorithm for establishing frame synchronism with parameters defined for the upper limit of the communication channel bit error probability P0_max = 0,495 for environments with a bit error probability P0 ≤ 0,495. The parameters of the algorithm for establishing frame synchronism with the upper limit of the communication channel bit error probability P0_max = 0,4 are determined. The efficiency of using the interleaving operation of fragments received from the communication channel is evaluated. The efficiency of implementing algorithms for establishing frame synchronism with parameters determined for the upper limit of the communication channel bit error probability P0_max ≤ 0,495 and P0_max = 0,4 is compared, for environments with a bit error probability P0 ≤ 0,4. We give recommendations for selecting the synchronization algorithm parameters for communication channels where the bit error probability upper limit P0 ≤ 0,4 is known, and for channels where this value is variable. These recommendations can be used to improve the efficiency of algorithms for establishing frame synchronism when designing telecommunication systems with non-separable data factorial coding in conditions of natural or artificially created high-level communication channel noise.

Design and implementation of variable coding and modulation for LEO high‐resolution Earth observation satellite

SummaryAs LEO (Low Earth Orbit) high‐resolution Earth observation satellite needs to transmit a large amount of remote sensing data from the satellite to the ground station, higher downlink capacity still poses a severe challenge to LEO. Therefore, variable coding and modulation (VCM) has become an important scheme to optimize the performance of satellite downlink. In this paper, the downlink VCM system of China Earth observation satellite is studied for the first time. By evaluating the free space loss of the satellite downlink path, a VCM‐based satellite downlink system is designed, and a DVB‐S2 BCH‐LDPC encoded variable bit rate high‐order MAPSK modulator is implemented. The maximum channel bit rate can reach 3.5 Gbps. Then, the experimental results of Gaofen‐7 satellite, which was launched in November 2019, are carried out which showed that our design method effectively meets the design requirements, and the performance is verified.

Hierarchical BEM Based Channel Estimation With Very Low Pilot Overhead for High Mobility MIMO-OFDM Systems

Channel estimation for multi-input multi-output orthogonal frequency division multiplexing (MIMO-OFDM) systems is a challenging issue in high mobility scenarios due to prohibitive pilot overhead and complexity. In this paper, a hierarchical basis expansion model (BEM) based channel estimation scheme is proposed for doubly selective channels, which requires a low pilot overhead and computational complexity. A mixed-BEM is proposed for time-varying channels alongside a complex exponential-BEM (CE-BEM), resulting in very few unknown parameters required for channel estimation. Based on the hierarchical BEM structure, an analytical channel estimation model is derived. By employing the block-structured sparsity and a small number of mixed-BEM coefficients in the antenna-time-BEM domain, a low-complexity estimator is proposed to recover the mixed-BEM coefficients accurately. The lower bound on the mean square error (MSE) of channel estimation is derived to verify the effectiveness of the proposed scheme. Simulation results show that the proposed channel estimation scheme significantly outperforms the existing methods in terms of MSE of channel estimation and bit error rate, with much lower pilot overhead and computational complexity.

Development of a method for increasing the interruption protection of multi-antenna systems with spectrally effective special purpose signals under the influence of destabilizing factors

The object of research is multi-antenna systems with spectrally efficient special purpose signals. The problematic issue, the solution of which is devoted to this research, is the improvement of immunity to interference of multi-antenna systems with spectrally efficient special purpose signals. A technique for improving the immunity of multi-antenna systems with spectrally efficient special-purpose signals under the influence of destabilizing factors has been developed. A distinctive feature of the proposed methodology is the use of an improved pre-coding procedure, evaluation of the channel state of multi-antenna radio communication systems with spectrally efficient signals by several indicators. The improved channel state estimation procedure consists in estimating channel bit error probability, channel state frequency response, and channel state impulse response. The formation of an estimate of the channel state for each of the assessment indicators takes place on a separate layer of the neural network using the apparatus of fuzzy sets, after which a generalized estimate is formed at the output of the neural network. The novelty of the proposed method also consists in the use of an improved procedure for forecasting the channel state of multi-antenna systems with spectrally efficient signals. The essence of the proposed procedure is the use of fuzzy cognitive models and an artificial neural network to predict the state of the channels of multi-antenna systems with spectrally efficient signals. Based on the results of the research, it was established that the proposed method allows to increase the immunity of multi-antenna systems with spectrally efficient signals according to the 8×8 scheme and 64 subcarriers by 20–25 % compared to the known ones.

Topology optimization of a heat-assisted magnetic recording write head to reduce transition curvature using a binary optimization algorithm utilizing the adjoint method

In this work, the possibility to reduce transition curvature in heat-assisted magnetic recording, using a conventional write head design, by shaping the recording field to counteract the circular profile of the heat pulse is investigated. Topology optimization of the head tip is performed in order to create the desired cross-track field profile for increasing distances from the write head tip. For the topology optimization, the adjoint method is utilized to calculate the necessary gradients and a binary optimization scheme is proposed. The optimizations are performed considering linearized material parameters reducing the computational complexity and the results are compared to optimizations incorporating the full non-linear material behavior. The optimized field profiles are evaluated for their influence on the read-back process. To do so, switching probability phase diagrams are calculated and the curvature parameter, the signal to noise ratio and the channel bit density are extracted. The presented results show that while transition curvature can be reduced by shaping the cross-track profile of the write field, this alone does not consequently lead to an improvement of the read back process. Therefore, completely new head designs, considering additional parameters have to be investigated.

Joint Bayesian Channel Estimation and Data Detection for OTFS Systems in LEO Satellite Communications

Lower earth orbit (LEO) satellites play an important role in the integration of space and terrestrial communication networks, which typically encounter high-mobility scenarios. It has been shown that orthogonal time frequency space (OTFS) modulation performs well in such high-mobility scenarios by transforming the time-varying channels into the delay-Doppler domain. In this paper, we develop a joint channel estimation and data detection algorithm for OTFS-based LEO satellite communications. Firstly, we adopt the powerful variational Bayesian inference (VBI) method for estimating the delay-Doppler channel vector, which contains the channel gain, the delay and the Doppler. Secondly, we exploit the unknown data symbols in an OTFS frame as ‘virtual pilots’ for improving the accuracy of channel estimation and detect them simultaneously. Our simulation results demonstrate that the proposed algorithm achieves improved channel estimation mean square error and bit error rate performance than its conventional counterparts.

Performance analysis and rain attenuation modelling of RoFSO link for hilly region of India

Abstract Free Space Optics (FSO) is one the most in-demand technology, and is used indoors, on the ground, in space, and even underwater. It is used to broaden communication access to places where bandwidth is insufficient or where difficult topography prevents the use of cable communications. One of the foremost communication challenges that contribute to the degradation of FSO performance is the environmental condition. Hilly regions experience heavy rainfall and have rough terrain which may demean the FSO link communication. In this work, for real-time rain rate analysis of the Meghalaya region two unique rain attenuation models are investigated for monsoon months from the years 2014 to 2020. Considering Marshall and Palmer’s model and by employing 8, 16 and 32-quadrature amplitude modulation (QAM) schemes, radio-over-free space optical (RoFSO) system has been evaluated by varying FSO channel range, power and bit rate.

Near-Optimal BEM OTFS Receiver With Low Pilot Overhead for High-Mobility Communications

In this paper, a new receiver design based on basis expansion model (BEM) orthogonal time frequency space (OTFS) is presented for high-mobility communications with Doppler-spread channel. By deriving an analytical BEM OTFS system model, a low-order generalized complex exponential BEM (GCE-BEM) aided rough channel estimation is proposed at the initial stage with low pilot overhead, followed by equalization. Then, the refinement of channel estimation and equalization is conducted iteratively, in which a high-resolution GCE-BEM model with a large BEM order is adopted and the detected data symbols are exploited as pseudo-pilots, leading to higher estimation accuracy. Simulation results show that the proposed BEM OTFS receiver significantly outperforms the existing OTFS receivers in terms of the mean square error (MSE) of channel estimation and bit error rate (BER), while featuring low pilot overhead. Results also show the near-optimal performance of the novel solution, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i.e.</i> , achieved BER is very close to the case of perfect channel estimation. The theoretical lower bound on MSE of channel estimation is derived to verify the effectiveness of the proposed BEM OTFS receiver, which is shown to be close to simulation results.

Evaluation of High-Speed Link Parameters for Highly Reliable Reconfigurable Systems Based on S-Parameters and BER

Purpose of research. is to improve signal transmission parameters in high-speed signal transmission lines, including between programmable logic integrated circuits (PLIC). This improvement in signal transmission parameters is necessary to increase throughput of modern highly reliable reconfigurable systems to ensure data transfer rate of up to tens of Gbit/s. It can be done considering the influence of electrical and structural parameters of multi-layer printed circuit boards (MPCB) on them. It is possible to provide such high data rates by using a wider frequency band of transmitted signals. One of the existing approaches to this problem is to increase "physical" frequency of transmitted information signals to 25-300 GHz, which is sufficient to achieve desired rates.Methods. A method for estimating quality of high-speed signal transmission lines based on the definition of standardized methods for analyzing signal transmission parameters, such as JCOM, S-parameters and BER is proposed in the article. This method allows evaluating high-speed communication lines. Thus, the Channel Operating Margin (COM)/JCOM parameter can be used to estimate the quality of a digital communication channel - a standardized method for determining the overall channel quality indicator. Known methods are used to estimate such signal transmission parameters as S11 reflection coefficient and S21 attenuation coefficient (S-Parameters). These methods are used to estimate attenuation and loss of the information signal in the path, when copies of the signal reflected from inhomogeneities affect the original and lead to its distortion. Simulation of such parameter as Bit Error Rate (BER) is carried out according to G.821/G.826/M2100 rationing and quality control methodology.Results. The main metrics were selected to evaluate the quality of high-speed signal transmission lines. It is based on the evaluation of such signal transmission parameters as Channel Operating Margin (COM), S-parameters and Bit Error Rate (BER). Numerical evaluations of signal transmission parameters were obtained and their effect on the design parameters of high-speed signal transmission lines was estimated. It is recommended to use at least 1 transition hole between screening polygons in GND separation layers every 0.5 cm or 0.25 cm2 of WFP area. It is for a data rate of less than 25 Gbit/s, It is recommended to use at least 2 transition holes between screening polygons in GND separation layers every 0.5 cm or 0.25 cm² of PV area, if high-speed signal transmission line passes at a distance of closer than 2.5 cm from the power supply circuits in a projection on the layer where the power supply circuits are located.Conclusion. A method for calculating signal transmission parameters on high-speed signaling lines based on the calculation of Channel Operating Margin (COM), S-parameters and Bit Error Rate (BER) parameters is introduced. As part of introduced method, an analysis of signal transmission parameters was carried out. This analysis shows that when the "reference" values of electrical parameters of the line are met, the transfer holes contribute most to the signal distortion; then the layers in which the signal line is located, the number of screening polygons between the signal layers and the layers; in which the power supply circuits, the design parameters of the transition holes, as well as the length and number of segments of the high-speed line pass. Numerical evaluations of minimum number of transition holes and their diameter, the length of segments of differential pairs are given. These results can be used in pre-layout analysis step of high-speed signal transmission lines for computational modules of highly reliable reconfigurable systems.

Evolution of distributed detection performance over balanced binary relay tree networks with bit errors

Target detection based on wireless sensor networks can be considered as a distributed binary hypothesis testing problem. In this paper, the evolution of detection error probability with the increase in the network scale is studied for the balanced binary relay tree network with channel noise. Firstly, the iterative expressions of false-alarm probability and missed-detection probability depending on the number of tree network layers are given. Then, the iterative process of two types of error probabilities in the network space is described as a discrete nonlinear switched dynamic system, and the dynamic properties of two types of error probabilities are analyzed in a plane rectangular coordinate system. A globally attractive invariant set of the state of the dynamic system, which is not related to the channel noise, is derived. The switching mode of the system and the total error probability in the invariant set are further analyzed, and a necessary and sufficient convergence condition of the total error probability is provided. Based on this condition, the following detection properties of the network are revealed: (1) as long as the channel bit error probability is not zero, the total error probability does not tend to zero as the network size grows to infinity; (2) when the channel bit error probability is greater than \(\frac{2-\sqrt{3}}{2}\), the total error probability will continue to increase with the increase in the network size.

Implementation of an enhanced 32 channel 256 Gbps DWDM based Radio over Fiber optical system for constricted channel spacing employing Fiber Bragg Grating

Radio over Fiber (RoF) systems form a crucial component of fifth generation (5G) mobile phone networks targeting higher capacity and better cost effectiveness in the existing telecommunication system architecture. An enhanced 32 channel 256 Gbps DWDM based RoF optical system incorporating DCF and FBG as dispersion compensators has been analyzed in Optisystem software, capable to transmit data at 8 Gbps per channel offering optimum signal reception over distances of 60 km and 120 km. Maximum Q factors of 15.34 and 15.97 were obtained for narrowed 50 GHz channel spacing for 60 km and 120 km respectively in 32 channel mode. The proposed system delivered very high Q factor of around 79 for 50 GHz channel spacing when operated in 8 channel mode at 4 Gbps per channel bit rate. Appreciable FWM side band power level reduction of average 6 dBm was also shown from the obtained spectrums. The transmission quality for long haul traversal (120 km) and constricted channel spacing (50 GHz) was observed to be much better than the existing WDM-RoF architectures.