- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Underwater optical wireless sensor networks using resource allocation
摘要： Optical wireless communications is an energy efficient and cost-effective solution for high speed and high secure wireless connections. In this paper, we propose an underwater optical wireless sensor network using multiple input multiple output technique and power allocation algorithm for supporting multiple users with the impacts of underwater channel uncertainty interferences. In proposed power allocation algorithm, all the LED nodes in are coordinated and controlled by a central controller; each LED node supports all the users within its field of view. To separate users, optical code division multiple access is used; cyclic optical orthogonal code working as CDMA code is employed. At the receiver, a minimal mean squared error (MMSE) filter is uniquely designed for each user. The MMSE filters and the assigned power can be jointly optimized to improve the overall throughput and signal to noise ratio. Since the system performance may be impacted by the underwater channel uncertainty, the proposed power allocation can use the predicted channel uncertainty variance to reduce the interference of the channel uncertainty and improve the signal to noise ratio. Compared to the equal power allocation algorithm, the proposed algorithm can support longer transmission distance, higher bit rate and lower bit error rate.
关键词： Multiple access interference,Underwater communications,Wireless sensor networks,Channel uncertainty,MIMO system,CDMA,Optical wireless communications,Resource allocation
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Coimbatore (2018.3.1-2018.3.3)] 2018 International Conference on Current Trends towards Converging Technologies (ICCTCT) - Generation and Analyzation of Spectral Density for IRNSS SPS PRN Code
摘要： The Indian Regional Navigational Satellite System (IRNSS) satellites provide two services namely standard Positioning Service (SPS) and Restricted Service (RS). L5 and S are the frequency bands from which both the services are utilized. To transmit the navigational information in SPS downlink gold codes are used. Most of the GNSS will work on the principle of CDMA where PRN sequences are the heart of the system. In this paper Pseudo Random Noise (PRN) codes are generated for an SPS signal which is called as SPS PRN code. A CDMA signal is generated using these sequences by using BPSK modulation. The analysis is done based on a time domain signal basis and is used to derive the Power Spectral Density of a CDMA signal. The spectrum analyser optimal operating conditions are observed by using the analytical results. To generate these codes, the polynomials G1 & G2 are selected, which are similar to ones used by GPS C/A signal and are as per the pre-conditions provided in IRNSS_SPS_ICD_June 2014. This paper also covers the process of selection of codes to be computed and the properties of PN-sequence are also analysed. The Xilinx ISE test system and Mat lab apparatus were used for the simulation of SPS PRN codes and additionally the implementation of PRN code is done on FPGA hardware wherein positive results have been obtained. These obtained simulated test results are within the theoretical limits.
关键词： ISE SIMULATOR,FPGA,CDMA,CORRELATION,PRN CODE
更新于2025-09-23 15:22:29
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Construction of Zero Correlation Zone Sequence Sets over the 16-QAM Constellation
摘要： Based on the known binary and quaternary zero correlation zone (ZCZ) sequence sets, a class of 16-QAM sequence sets with ZCZ is presented, where the term “QAM sequence” means the sequence over the quadrature amplitude modulation (QAM) constellation. The sequence sets obtained by this method achieve an expansion in the number of 16-QAM sequence sets with ZCZ. The proposed sequence sets can be applied to quasi-synchronous code division multiple access (QS-CDMA) systems to eliminate the multiple access interference (MAI) and multipath interference (MPI) and improve the transmission data rate (TDR).
关键词： zero correlation zone (ZCZ),QS-CDMA,16-QAM sequence,filtering operation
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - High Performance GaAs Solar Cells Grown at High Growth Rates by Atmospheric-Pressure Dynamic Hydride Vapor Phase Epitaxy
摘要： In this treatise, we evaluate the error-rate (ER) performance of turbo-coded multi-carrier code division multiple access scheme (MC-CDMA) for downlink (DL) transmission. The transmitter pre-processing (TP) technique is a promising signal processing technique, which is carried out at the transmitter side to reduce the burden of each mobile station (MS) in the context of DL communication. We formulate minimum mean-square-error-aided TP matrix using noisy feedback of vector-quantized estimated channel information (CI) for frequency-division duplexing system. Clearly, we estimate the CI and perform vector quantization (VQ) at each MS and transmit the index of the quantized value through dedicated low rate noisy channel. Finally, we acquire CI of all active users using known estimation algorithm in order to build TP. We realize time-frequency domain signature sequence to support more user population. In particular, we analyze the ER performance of coded MC-CDMA system with TP for Stanford University Interim channel model. The ER curve shows that coded MC-CDMA system based on TP approach provides better performance with less signal-to-noise ratio while offering low complexity of MS. In addition, performance curve shows that there is an improvement in the ER performance when perfect CI is utilized to build TP matrix compared with noise-contaminated VQ-CI.
关键词： Code division multiple access (CDMA),minimum mean-square-error (MMSE),zero forcing (ZF),interleave division multiple access (IDMA),transmitter pre-processing (TP),vector quantization(VQ)
更新于2025-09-23 15:19:57
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[IEEE 2019 21st International Middle East Power Systems Conference (MEPCON) - Cairo, Egypt (2019.12.17-2019.12.19)] 2019 21st International Middle East Power Systems Conference (MEPCON) - Performance Investigation for Tracking GMPP of Photovoltaic System Under Partial Shading Condition Using Coyote Algorithm
摘要： As wireless communication has become completely integrated into people’s day-to-day lives, so has its reliance on wireless connectivity. The Centers for Disease Control reports that in 2013 39.4% of the U.S. population did not own a traditional wired telephone. While the convenience of a wireless phone is clear, it has created a situation where it is the only communication device that people have during a natural disaster. Far too often during disasters communications with these devices fail, often occurring in one of two ways. First, natural disasters destroy the network hardware that provides the required network connectivity. Second, as people need these devices for safety and security, the network that these devices utilize becomes overloaded. The research in this paper provides evidence that there is a statistically measurable increase in wireless communication traf?c during a severe winter storm. This empirical study explores the increase of voice minutes of use and text messaging during a severe winter storm.
关键词： Code division multiple access (CDMA),disaster,winter storms,traf?c volume
更新于2025-09-19 17:13:59
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Electrically injected $1.64\ \boldsymbol{\mu} \mathbf{m}$-emitting In <sub/>0.65</sub> Ga <sub/>0.35</sub> As 3-QW laser diodes grown on mismatched substrates by MOVPE
摘要： In this treatise, we evaluate the error-rate (ER) performance of turbo-coded multi-carrier code division multiple access scheme (MC-CDMA) for downlink (DL) transmission. The transmitter pre-processing (TP) technique is a promising signal processing technique, which is carried out at the transmitter side to reduce the burden of each mobile station (MS) in the context of DL communication. We formulate minimum mean-square-error-aided TP matrix using noisy feedback of vector-quantized estimated channel information (CI) for frequency-division duplexing system. Clearly, we estimate the CI and perform vector quantization (VQ) at each MS and transmit the index of the quantized value through dedicated low rate noisy channel. Finally, we acquire CI of all active users using known estimation algorithm in order to build TP. We realize time-frequency domain signature sequence to support more user population. In particular, we analyze the ER performance of coded MC-CDMA system with TP for Stanford University Interim channel model. The ER curve shows that coded MC-CDMA system based on TP approach provides better performance with less signal-to-noise ratio while offering low complexity of MS. In addition, performance curve shows that there is an improvement in the ER performance when perfect CI is utilized to build TP matrix compared with noise-contaminated VQ-CI.
关键词： zero forcing (ZF),transmitter pre-processing (TP),interleave division multiple access (IDMA),vector quantization(VQ),Code division multiple access (CDMA),minimum mean-square-error (MMSE)
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 2nd British and Irish Conference on Optics and Photonics (BICOP) - London, United Kingdom (2019.12.11-2019.12.13)] 2019 IEEE 2nd British and Irish Conference on Optics and Photonics (BICOP) - Temperature Stability of Elastomeric Colloidal Quantum Dot Colour Converter
摘要： Underwater wireless optical communications are an emerging solution to the expanding demand for broadband links in oceans and seas. In this paper, a cellular underwater wireless optical code division multiple-access network is proposed to provide broadband links for commercial and military applications. The optical orthogonal codes are employed as signature codes of underwater mobile users. Fundamental key aspects of the network, such as its backhaul architecture, its potential applications, and its design challenges, are presented. In particular, a promising underwater localization and positioning scheme based on this cellular network is presented. Furthermore, the proposed network is used as infrastructure of centralized, decentralized and relay-assisted underwater sensor networks for high-speed real-time monitoring. Finally, probable design challenges, such as cell edge coverage, blockage avoidance, power control, and network capacity, are addressed.
关键词： power control,optical CDMA networks,undersea localization and positioning,underwater sensor networks,Underwater wireless optical communications,relay-assisted transmission
更新于2025-09-19 17:13:59
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Clock and Data Recovery-Free Data Communications Enabled by Multi-core Fiber with Low Thermal Sensitivity of Skew
摘要： Underwater wireless optical communications are an emerging solution to the expanding demand for broadband links in oceans and seas. In this paper, a cellular underwater wireless optical code division multiple-access network is proposed to provide broadband links for commercial and military applications. The optical orthogonal codes are employed as signature codes of underwater mobile users. Fundamental key aspects of the network, such as its backhaul architecture, its potential applications, and its design challenges, are presented. In particular, a promising underwater localization and positioning scheme based on this cellular network is presented. Furthermore, the proposed network is used as infrastructure of centralized, decentralized and relay-assisted underwater sensor networks for high-speed real-time monitoring. Finally, probable design challenges, such as cell edge coverage, blockage avoidance, power control, and network capacity, are addressed.
关键词： power control,relay-assisted transmission,Underwater wireless optical communications,undersea localization and positioning,underwater sensor networks,optical CDMA networks
更新于2025-09-19 17:13:59
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Study on the Effect of System Parameters on Physical-Layer Security of Optical CDMA Systems
摘要： Optical CDMA (OCMDA) technology directly encrypts optical transmission links at the physical layer, which can improve the security of communication system against fibre-optic eavesdropping attacks. System parameters will affect the performances of OCDMA systems, based on the wiretap channel model of OCDMA systems, “secrecy capacity” is employed as an indicator to estimate the effects of system parameters (the type of code words, the length of code words) on the security of the systems. Simulation results demonstrate that system parameters play an important role and choosing the code words with better cross-correlation characteristics can improve the security of OCDMA systems.
关键词： Wiretap Channel Model,Secrecy Capacity,System Parameters,Physical-Layer Security,Optical CDMA (OCDMA)
更新于2025-09-16 10:30:52
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[IEEE 2018 9th Advanced Satellite Multimedia Systems Conference and the 15th Signal Processing for Space Communications Workshop (ASMS/SPSC) - Berlin (2018.9.10-2018.9.12)] 2018 9th Advanced Satellite Multimedia Systems Conference and the 15th Signal Processing for Space Communications Workshop (ASMS/SPSC) - Low Complexity Detectors for Spread Spectrum Receivers
摘要： In the context of the recent solutions proposed in the 3GPP for standardization group on NOMA (Non-Orthogonal Multiple Access) schemes, this paper discusses different approaches for implementing an approximate spread spectrum MMSE (Minimum Mean Square Error) detector. In addition, the implication of such detectors on the signal design is presented.
关键词： Random Access,NOMA,CDMA,MMSE,spread spectrum
更新于2025-09-09 09:28:46