Channel Signal Research Articles

MIMO optical communication systems based on broadband transmitters and receivers

A multiple-input multiple-output (MIMO) optical communication system is proposed. In the MIMO optical communication system, a series of broadband sources with different spectra act as the transmitters, and a compact imaging chip sensor accompanied by a disorder dispersion component and a calculating component serve as the receivers. Because the spectral ranges of the sources are overlapped, the number of the signal channels is not restricted by the bandwidth of the communication band and the characteristics of the sources. L1-norm regularization, L2-norm regularization, and the simulated annealing algorithms are used to solve matrix equations for decoding the signals at the receivers. A proof-of-concept experiment using on-off keying modulation has been done to prove the feasibility of the design. The experimental results demonstrate that the signals decoded by the receivers fit well with those generated from the transmitters. Besides the function of communications, the broadband sources are suitable to act as illumination sources because the white color lights in the visible band are more comfortable for human eyes compared with monochromatic lights used in traditional visible light communication (VLC) systems. We also prove that the MIMO optical communication system can operate in the infrared band. The infrared communication (IC) system has potential applications in situations requiring communication in a dark environment that cannot be realized by VLC systems.

Exploring hormonal regulation and candidate genes in leaflet nyctinasty of Averrhoa carambola

Averrhoa carambola, a commonly cultivated tree, exhibits leaflet nyctinastic movement. However, the underlying mechanism remains unclear. The pulvinus, as a motor organ, coordinates the motion of its attached leaflet. During the leaflet expansion, flexor cells shift from contraction to expansion, with concurrent expansion and fusion of vacuole. In contrast, the extensor cells move from expansion to contraction, causing vacuole contraction and increased vacuole numbers. During the process of leaflet expansion and closure, the contents of IAA and IPA in flexor muscles increased significantly, but did not show significant changes in extensor muscles, BR content showed an opposite trend in extensor and flexor muscles, and the content of ZR increased significantly in extensor muscles but decreased significantly in flexor muscles, and ZR content only decreased in extensor muscles, but did not show significant changes in flexor muscles. Exogenous IAA (50–100 μM) significantly aids in leaflet unfolding during night time. Transcriptome analysis reveals gene enrichment in circadian rhythms, hormone signaling, ion channels, and other pathways during leaflet opening and closure. The expression of AcaCRY3, AcaPHOT1–1, AcaAPRR2, AcaLHY, and AcaAKT1–1 is prominent during expansion, while AcaAUX22–1 stands out during closure. These findings suggest a potential regulatory pathway in A. carambola 'Daguo Tianyangtao 2′ leaflets, involving light, circadian rhythm, hormone signaling, and ion channels. Findings of this study can do a great deal to broaden the plant nyctinastic movement research.

Effect of endocrine-disrupting chemicals on the expression of a calcium ion channel receptor (ryanodine receptor) in the mud crab (Macrophthalmus japonicus)

Endocrine-disrupting chemicals (EDCs) are toxic pollutants generated by artificial activities. Moreover, their hormone-like structure induces disturbances, such as mimicking or blocking metabolic activity. Previous studies on EDCs have focused on the adverse effect of the endocrine system in vertebrates, with limited investigations conducted on ion channels in invertebrates. Thus, in this study, we investigated the potential adverse effects of exposure to bisphenol-A (BPA) and di-(2-ethylhexyl) phthalate (DEHP) at the molecular level on the ryanodine receptor (RyR), a calcium ion channel receptor in Macrophthalmus japonicus. In the phylogenetic analysis, the RyR amino acid sequences in M. japonicus clustered with those in the Crustacean and formed separated branches for RyR in insects and mammals. When exposed to 1 μg L−1 BPA, a significant increase in RyR mRNA expression was observed in the gills on day 1, although a similar level to the control group was observed from day 4 to day 7. However, the RyR expression due to DEHP exposure decreased on days 1 and 4, although it increased on day 7 following exposure to 10 μg L−1. The RyR expression pattern in the hepatopancreas increased for up to 4 days, depending on the BPA concentration. However, there was a tendency for the expression to decrease gradually after the statistical significance increased during the early stage of DEHP exposure (D1). Hence, the transcriptional alterations in the M. japonicus RyR gene observed in the study suggest that exposure toxicities to EDCs, such as BPA and DEHP, have the potential to disrupt calcium ion channel signaling in the gills and hepatopancreas of M. japonicus crabs.

Short-term epileptic seizures prediction based on cepstrum analysis and signal morphology

This article aims to provide and implement a patient-specific seizure (for Intervention Time (IT) detection) prediction algorithm using non-invasive data to develop warning devices to prevent further patient injury and reduce stress. Employing algorithms with high initial data volume and computations time to increase the accuracy is an important problem in prediction issues. Consequently, reduction of calculations is met by applying only two effective EEG signal channels without manual removal of artifacts by visual inspection as the algorithm’s input. Autoregression (AR) modeling and Cepstrum detect changes due to IT period. We carry out the goal of higher accuracy by increasing sensitivity to interictal epileptiform discharges or artifacts and reduce errors caused by them, taking advantage of the discrete wavelet transform and the comparison of two channels epochs by applying the median filter. Averaging and positive envelope methods are introduced to patient-specific thresholds become more differentiated as soon as possible and can be lead to sooner prediction. We examined this method on a mathematical model of adult epilepsy as well as on 10 patients with EEG data. The results of our experiments confirm that performance of the proposed approach in accuracy and average false prediction rate is superior to other algorithms. Simulation results have been shown the robustness of our proposed method to artifacts and errors, which is a step towards the development of real-time alarm devices by non-invasive techniques.

BK Channels in Tail Artery Vascular Smooth Muscle Cells of Normotensive (WKY) and Hypertensive (SHR) Rats Possess Similar Calcium Sensitivity But Different Responses to the Vasodilator Iloprost.

It has been reported that, in the spontaneously hypertensive rat (SHR) model of hypertension, different components of the G-protein/adenylate cyclase (AC)/Calcium-activated potassium channel of high conductance (BK) channel signaling pathway are altered differently. In the upstream part of the pathway (G-protein/AC), a comparatively low efficacy has been established, whereas downstream BK currents seem to be increased. Thus, the overall performance of this signaling pathway in SHR is elusive. For a better understanding, we focused on one aspect, the direct targeting of the BK channel by the G-protein/AC pathway and tested the hypothesis that the comparatively low AC pathway efficacy in SHR results in a reduced agonist-induced stimulation of BK currents. This hypothesis was investigated using freshly isolated smooth muscle cells from WKY and SHR rat tail artery and the patch-clamp technique. It was observed that: (1) single BK channels have similar current-voltage relationships, voltage-dependence and calcium sensitivity; (2) BK currents in cells with a strong buffering of the BK channel activator calcium have similar current-voltage relationships; (3) the iloprost-induced concentration-dependent increase of the BK current is larger in WKY compared to SHR; (4) the effects of activators of the PKA pathway, the catalytic subunit of PKA and the potent and selective cAMP-analogue Sp-5,6-DCl-cBIMPS on BK currents are similar. Thus, our data suggest that the lower iloprost-induced stimulation of the BK current in freshly isolated rat tail artery smooth muscle cells from SHR compared with WKY is due to the lower efficacy of upstream elements of the G-Protein/AC/BK channel pathway.

Involvement of ObRb receptor, nitric oxide, and BKCa channel signaling pathways in leptin-induced relaxation of pregnant mouse uterus

The purpose of this study was to determine the receptor subtype and the underlying mechanisms involved in the relaxant effect to leptin in mid- and late-pregnant mouse uterus. We determined the relative mRNA expression of receptor subtypes, eNOS, and BKCa channel by quantitative PCR and also the overall receptor expression by immunohistochemistry. Isometric tension studies were conducted to evaluate the effects of leptin and to delineate its mechanisms. A selective siRNA for the ObRb receptor was used to determine the participation of the receptor subtype in biochemical and molecular effects of leptin.The relaxant response to leptin was greater in mid-pregnancy compared to late pregnancy and was mediated by the activation of BKCa channels by eNOS-derived nitric oxide in an ObRb receptor-dependent manner. In comparison to mid-pregnancy, expression of short forms (mainly ObRa receptor) of the receptor was significantly increased in late pregnancy, whereas ObRb receptor expression was similar in both phases.The results of the study suggest that ObRb receptor mediates leptin-induced increase in eNOS expression and NO synthesis. Leptin-induced eNOS expression and activation cause cGMP-independent stimulation of BKCa channels causing uterine relaxation. Increased short forms of the receptors and reduced BKCa channels exert a negative effect on uterine relaxation in late pregnancy. Leptin may have a physiological role in maintaining uterine quiescence in mid-pregnancy and its reduced relaxant response in late gestation may facilitate labor. Further, ObRb receptor agonists may be useful in the management of preterm labor.

Graph-Based Electroencephalography Analysis in Tinnitus Therapy.

Tinnitus is the perception of sounds like ringing or buzzing in the ears without any external source, varying in intensity and potentially becoming chronic. This study aims to enhance the understanding and treatment of tinnitus by analyzing a dataset related to tinnitus therapy, focusing on electroencephalography (EEG) signals from patients undergoing treatment. The objectives of the study include applying various preprocessing techniques to ensure data quality, such as noise elimination and standardization of sampling rates, and extracting essential features from EEG signals, including power spectral density and statistical measures. The novelty of this research lies in its innovative approach to representing different channels of EEG signals as new graph network representations without losing any information. This transformation allows for the use of Graph Neural Networks (GNNs), specifically Graph Convolutional Networks (GCNs) combined with Long Short-Term Memory (LSTM) networks, to model intricate relationships and temporal dependencies within the EEG data. This method enables a comprehensive analysis of the complex interactions between EEG channels. The study reports an impressive accuracy rate of 99.41%, demonstrating the potential of this novel approach. By integrating graph representation and deep learning, this research introduces a new methodology for analyzing tinnitus therapy data, aiming to contribute to more effective treatment strategies for tinnitus sufferers.

FGF signaling modulates mechanotransduction/WNT signaling in progenitors during tooth root development

Stem/progenitor cells differentiate into different cell lineages during organ development and morphogenesis. Signaling pathway networks and mechanotransduction are important factors to guide the lineage commitment of stem/progenitor cells during craniofacial tissue morphogenesis. Here, we used tooth root development as a model to explore the roles of FGF signaling and mechanotransduction as well as their interaction in regulating the progenitor cell fate decision. We show that Fgfr1 is expressed in the mesenchymal progenitor cells and their progeny during tooth root development. Loss of Fgfr1 in Gli1+ progenitors leads to hyperproliferation and differentiation, which causes narrowed periodontal ligament (PDL) space with abnormal cementum/bone formation leading to ankylosis. We further show that aberrant activation of WNT signaling and mechanosensitive channel Piezo2 occurs after loss of FGF signaling in Gli1-CreER;Fgfr1fl/fl mice. Overexpression of Piezo2 leads to increased osteoblastic differentiation and decreased Piezo2 leads to downregulation of WNT signaling. Mechanistically, an FGF/PIEZO2/WNT signaling cascade plays a crucial role in modulating the fate of progenitors during root morphogenesis. Downregulation of WNT signaling rescues tooth ankylosis in Fgfr1 mutant mice. Collectively, our findings uncover the mechanism by which FGF signaling regulates the fate decisions of stem/progenitor cells, and the interactions among signaling pathways and mechanotransduction during tooth root development, providing insights for future tooth root regeneration.

GLONASS-K2 signal analysis

K2 is a new generation of GLONASS satellites that provides code division multiple access (CDMA) signals in the L1, L2 and L3 frequency bands in addition to legacy L1 and L2 signals based on frequency division multiple access (FDMA) modulation. The first GLONASS-K2 satellite was launched in August 2023 and started signal transmission in early September 2023. Based on measurements with a 30-m high-gain antenna, spectral characteristics of the various signal components are described and relative power levels are identified. A 3 dB (L1) to 4 dB (L2) higher total power is determined for the CDMA signal compared to the legacy FDMA signal and an equal power of the open service and secured CDMA signal components is found. The ranging code of the L2 channel for service information, which has not been publicly disclosed so far, is identified as a Gold code sequence consistent with the data channel of the L1 open service CDMA signal. The high-gain antenna measurements are complemented by tracking data from terrestrial receivers that enable a first assessment of user performance. An up to 50% improvement in terms of noise and multipath performance is demonstrated for the new L1 and L2 CDMA signals in comparison with their legacy counterpart, but no obvious differences between the different binary phase-shift keying and binary offset carrier modulations of the data and pilot components of these signals could be identified for the test stations. Triple-frequency carrier phase observations from L1, L2, and L3 CDMA signals exhibit good consistency at the noise and multipath level, except for small variations that can be attributed to slightly different antenna phase patterns on the individual frequencies. Overall, the new CDMA signals are expected to notably improve and facilitate precise point positioning applications once fully deployed across the GLONASS constellation.

A simplified method for relapsing-remitting multiple sclerosis detection: Insights from resting EEG signals

Background and Objective:Multiple sclerosis (MS) is a neurodegenerative autoimmune disease affecting the central nervous system, leading to various neurological symptoms. Early detection is paramount to prevent enduring damage during MS episodes. Although magnetic resonance imaging (MRI) is a common diagnostic tool, this study aims to explore the feasibility of using electroencephalography (EEG) signals for MS detection, considering their accessibility and ease of application compared to MRI. Methods:The study involved the analysis of EEG signals during rest from 17 MS patients and 27 healthy volunteers to investigate MS-healthy patterns. Power spectral density features (PSD) were extracted from the 32-channel EEG signals. The study employed Linear Discriminant Analysis (LDA), Support Vector Machine (SVM), Classification and Regression Trees (CART), and k-Nearest Neighbor (kNN) classifiers to identify channels with the highest accuracy. Notably, the study achieved 100% accuracy in MS detection using the “Fp1” and “Pz” channels with the LDA classifier. A statistical analysis, utilizing the independent sample t-test, was conducted to explore whether PSD features of these channels differed significantly between healthy individuals and those with MS. Results:The results of the study demonstrate that effective detection of MS can be achieved using PSD features from only two channels of the EEG signal. Specifically, the “Fp1” and “Pz” channels exhibited 100% accuracy in MS detection with the LDA classifier. The statistical analysis further explored and confirmed the significant differences in PSD features between healthy individuals and MS patients. Conclusion:The study concludes that the proposed method, utilizing PSD features from specific EEG channels, offers a straightforward and efficient diagnostic approach for the effective detection of MS. The findings suggest the potential utility of EEG signals as a non-invasive and accessible alternative for MS detection, highlighting the importance of further research in this direction.

Research on Response Characteristics of GPR Method for Detecting Phreatic Lines in Embankments

The excessive elevation of the phreatic lines under continuous high-water levels is the cause of many dangerous situations in embankments. Therefore, accurately understanding the dynamic changes in the infiltration characteristics of embankments is of great significance for judging and evaluating the stability of engineering. This study conducted indoor model experiments and used ground penetrating radar to detect the phreatic lines of soil. By comparing the radar detection results with the measured position of the phreatic lines, it was determined that the phreatic lines appeared as a continuous strong reflection surface with similar shapes in the radargram, and the reflection below the reflection surface became weaker. Through time-domain analysis of the single waveform at different time points, it was found that the amplitude of the reflected wave at the saturation line was larger, and the energy attenuation below the saturation line was faster, resulting in a rapid decrease in amplitude; perform Fourier transform on a single channel signal to obtain a spectrogram, and perform frequency domain analysis on it. The main frequency is around 600MHz, and the second main frequency is around 900MHz. As the saturation line rises, the main frequency gradually shifts towards lower frequencies.

A novel lysosome-targeting BODIPY-based fluorescent probe with two near-infrared channel signals for ratiometric detection of HClO and its application in diabetes mice model

Diabetes is an endocrine and metabolic disease characterized by hyperglycemia, which can lead to a variety of serious complications. Hypochlorous acid (HClO), one of the significant members of reactive oxygen species (ROS), is essential for various physiological processes, and the acidic lysosomes of phagocytes are one of its main sources. The related studies suggest that abnormal levels of HClO in the body have a strong association with diabetic process, but the pathological mechanisms of HClO on diabetic diseases are still unclear. Here, a novel ratiometric lysosome-targeted BODIPY-based fluorescence probe Lyso-HClO was designed for specific recognition of HClO. Lyso-HClO could rapidly sense HClO within 20 s, and its limit of detection was calculated as low as 45 nM. Both the emission wavelengths of Lyso-HClO before and after reaction of HClO reached the near-infrared region, which effectively reduced tissue damage and eliminated background interference from organisms to achieve more accurate analysis. Lyso-HClO was successfully employed for fluorescence imaging of both exogenous and endogenous HClO in RAW264.7 cells, HepG2 cells, and zebrafish. Additionally, it was effectively utilized to monitor the HClO fluctuations in diabetic mice, exhibiting a 15-fold increase in the fluorescence signal ratio (I650/I685). Therefore, the probe Lyso-HClO has enormous potential for the early diagnosis and prevention of diabetes and its complications.

Development of multi-channel magnetic flux leakage testing system for bridge cables

Magnetic flux leakage (MFL) is one of the most popular techniques for detecting broken wire in bridge cables. MFL sensor array has attracted a lot of attention in recent years due to its capacity to measure the spatial distribution of the magnetic field of bridge cable. More sensors in the array lead to increased useful information extraction from the MFL field, allowing for more precise quantitative evaluation of bridge cable damage. This study reports the development of a cable MFL testing system capable of synchronous acquiring up to 512 channels of MFL sensors signal. Radial sensor arrays (RSA) composed of vertically placed magnetic sensors spaced at equal intervals are developed to be arranged around the bridge cable. They record the spatial distribution of the magnetic leakage field of the broken wire by collecting the MFL signal at various lift-offs. To solve the problem of multi- channel MFL signal synchronous acquisition, this study develops a MFL signal acquisition card based on multiplexing technology, capable of synchronous acquisition of up to 512 channels of MFL signal. Multiplexers are used to switch sensor channels, followed by multi-channel A/D conversion chips to convert the transmitted data. The converted data are temporally stored in the First-In-First-Out (FIFO) buffer of the Field Programmable Gate Array (FPGA) and transferred to the computer through the network port for display, storage, and signal processing. Finally, the motion control circuit, mechanical structure, and control software of the bridge cable MFL testing system are fully customized. Experiment results reveal that the system can be used in multi-channel MFL testing, laying the foundation for further multi-channel signal processing and bridge cable health evaluation.

P‐76: The Influence of Bending FFC Transmission Line on High‐Speed Signal Channels

Generally, display devices interconnect FFC transmission lines with circuits to form a transmission line network system to achieve data communication between Tcon and Driver. Due to the limitations of the external shape and internal space structure of the display device, the FFC transmission cable presents a curved shape from 0 to 180 degrees during the wiring process. Under the action of spatial electromagnetic fields, the display device will involve the field‐circuit hybrid problem of electromagnetic coupling of the FFC transmission line's bent line and circuit conduction interference, which will cause severe electromagnetic interference(EMI), resulting in deterioration of the high‐speed channel signal at the receiving end and even inability to correctly restore and decode the signal, thus causing signal distortion, which in turn leads to display image distortion or pixel loss.

Exploring Importance and Regulation of Autophagy in Cancer Stem Cells and Stem Cell-Based Therapies.

Autophagy is a globally conserved cellular activity that plays a critical role in maintaining cellular homeostasis through the breakdown and recycling of cellular constituents. In recent years, there has been much emphasis given to its complex role in cancer stem cells (CSCs) and stem cell treatment. This study examines the molecular processes that support autophagy and how it is regulated in the context of CSCs and stem cell treatment. Although autophagy plays a dual role in the management of CSCs, affecting their removal as well as their maintenance, the intricate interaction between the several signaling channels that control cellular survival and death as part of the molecular mechanism of autophagy has not been well elucidated. Given that CSCs have a role in the development, progression, and resistance to treatment of tumors, it is imperative to comprehend their biological activities. CSCs are important for cancer biology because they also show a tissue regeneration model that helps with organoid regeneration. In other words, the manipulation of autophagy is a viable therapeutic approach in the treatment of cancer and stem cell therapy. Both synthetic and natural substances that target autophagy pathways have demonstrated promise in improving stem cell-based therapies and eliminating CSCs. Nevertheless, there are difficulties associated with the limitations of autophagy in CSC regulation, including resistance mechanisms and off-target effects. Thus, the regulation of autophagy offers a versatile strategy for focusing on CSCs and enhancing the results of stem cell therapy. Therefore, understanding the complex interactions between autophagy and CSC biology would be essential for creating therapeutic treatments that work in both regenerative medicine and cancer treatment.

AI-DRIVEN TRANSFORMER NETWORKS IN SHARED SPECTRUM FOR ENHANCED SIGNAL PROCESSING FOR NONLINEAR RECEIVERS

Communication systems face challenges from high-power adjacent channel signals, or blockers, inducing nonlinear behavior in RF front ends. Ensuring robust performance in the presence of blockers is crucial for IoT and other spectrum-consuming devices coexisting with advanced transceivers. This paper proposes a flexible, data-driven solution using a Deep Belief Network (DBN) to mitigate third-order intermodulation distortion (IMD) during demodulation. Numerical evaluations of AI-enhanced receivers employing DBN as an IMD canceler and demodulator show significant improvements in bit error rate (BER) performance. The effectiveness of DBN varies with RF front end characteristics, notably the third-order intercept point (IP3).

Neuroanatomical, transcriptomic, and molecular correlates of math ability and their prognostic value for predicting learning outcomes.

Foundational mathematical abilities, acquired in early childhood, are essential for success in our technology-driven society. Yet, the neurobiological mechanisms underlying individual differences in children's mathematical abilities and learning outcomes remain largely unexplored. Leveraging one of the largest multicohort datasets from children at a pivotal stage of knowledge acquisition, we first establish a replicable mathematical ability-related imaging phenotype (MAIP). We then show that brain gene expression profiles enriched for candidate math ability-related genes, neuronal signaling, synaptic transmission, and voltage-gated potassium channel activity contributed to the MAIP. Furthermore, the similarity between MAIP gene expression signatures and brain structure, acquired before intervention, predicted learning outcomes in two independent math tutoring cohorts. These findings advance our knowledge of the interplay between neuroanatomical, transcriptomic, and molecular mechanisms underlying mathematical ability and reveal predictive biomarkers of learning. Our findings have implications for the development of personalized education and interventions.

A comparative study of deep learning and iterative algorithms for joint channel estimation and signal detection in OFDM systems

Joint channel estimation and signal detection (JCESD) is crucial in orthogonal frequency division multiplexing (OFDM) systems, but traditional algorithms perform poorly in low signal-to-noise ratio (SNR) scenarios. Deep learning (DL) methods have been investigated, but concerns regarding computational expense and lack of validation in low-SNR settings remain. Hence, the development of a robust and low-complexity model that can deliver excellent performance across a wide range of SNRs is highly desirable. In this paper, we aim to establish a benchmark where traditional algorithms and DL methods are validated on different channel models, Doppler, and SNR settings, particularly focusing on the semi-blind setting. In particular, we propose a new DL model where the backbone network is formed by unrolling the iterative algorithm, and the hyperparameters are estimated by hypernetworks. Additionally, we adapt a lightweight DenseNet to the task of JCESD for comparison. We evaluate different methods in three aspects: generalization in terms of bit error rate (BER), robustness, and complexity. Our results indicate that DL approaches outperform traditional algorithms in the challenging low-SNR setting, while the iterative algorithm performs better in high-SNR settings. Furthermore, the iterative algorithm is more robust in the presence of carrier frequency offset, whereas DL methods excel when signals are corrupted by asymmetric Gaussian noise.

SiPM joint likelihood reception for mobile LED-optical communication under pointing errors.

Light-emitting diode (LED)-optical communication is a novel spectrum communication with wide field of view (FOV), light weight, and long-distance free-space capabilities. Due to atmospheric turbulence attenuation and pointing errors caused by long-distance communication, this Letter proposes a multi-pixel channel joint maximum likelihood (JML) reception method using a highly sensitive silicon photomultiplier (SiPM). To evaluate the performance of the SiPM under mobile terminal jittering communication, we analyze the effect of optical transmitting power, pointing errors, and signal-to-noise ratio (SNR) gain on optical communication by comparing JML with signal channel using the maximum likelihood (ML) algorithm. Both simulation analysis and experimental results demonstrate that the proposed JML algorithm to process signals received from SiPM multi-pixel channels can effectively mitigate the impact of pointing errors on the bit error rate (BER) of optical communications by two orders of magnitude at large jitter radians and SNR.

Reconfigurable optical add/drop multiplexing-demultiplexing in arrayed waveguide grating with fold back technique

We propose a reconfigurable optical add/drop multiplexer-demultiplexer based on arrayed waveguide grating with fold-back technique in AWG. The design with 8 channels incorporates a routing network in the fold-back path to allocate optical signals for the add/drop function without disrupting other signal which improves the add/drop function, enabling the allocation of multiple signal channels. The use of the fold-back path also reduces the signal crosstalk to about −70dB. During data transmission, the eye diagram analyses indicate a bit error rate of less than 0.009for a speed up to 25Gbps.