- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Novel Sub-carriers Iterative Restructuring Method in OFDM: Toward Extra Equalization Omitted
摘要： This study considered a receiver equalization problem in wireless communication area. Receiver equalizations in OFDM proceeding through sub-carriers variedness in frequency guarantee transmit system bit error rate thus are essential. E.g., Zero-Forcing (ZF) equalization, Minimal Mean Square Equalization (MMSE), which can also be considered as channel Estimation (EE) and detection schemes. However, some methods like adaptive equalizations must count priority transceiver information thus may be not practical although they raise performances for receiver. This study considers equalization and detection problems through a sub-carriers restructuring method to omit any complicated extra equalization in receiver except ZF equalization following the elemental LS channel estimation. Optimal constraints model is utilized which leads to an optimal sub-carriers derivation, moreover, we iteratively set up constraints model and give derivation, then under our new sub-carriers no extra equalization is needed. Simulations verify the novel method can approach MMSE equalization although it may bring transceiver complexity.
关键词： extra equalization,restructuring,OFDM,optimal sub-carriers,Channel estimation
更新于2025-09-10 09:29:36
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[IEEE 2018 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM) - Munich, Germany (2018.4.15-2018.4.17)] 2018 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM) - Spectrum-efficient real-time OFDM MIMO Radar for moving target detection in medium-range applications
摘要： This paper presents the first measurement results of a new Orthogonal Frequency Division Multiplexing (OFDM) Multiple Input Multiple Output (MIMO) Radar prototype. It is designed to be operated in a dynamic multi-user environment where the individual sensor’s RF bandwidth is very limited. Here, the radar uses only 30 MHz. The targeted applications are in the field of Urban (Air) Mobility (UAM) with a medium-range coverage up to 250 m. Another requirement is to observe a wide field of view in azimuth of about 100 degree with a high resolution in azimuth. This was implemented by using a 2 x 8 MIMO processing. A 20 ms frame based evaluation of the OFDM symbols allows to obtain a very high velocity resolution of below 1 m/s. This paper explains details about the radar system, the waveform and the processing but the main part of the paper focuses on the evaluation of a dynamic measurement.
关键词： OFDM,MIMO,Radar
更新于2025-09-10 09:29:36
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Channel Estimation and Equalization for SS-OOFDM System with High Mobility
摘要： When orthogonal frequency division multiplexing (OFDM) is used in high-speed mobile scenarios, the traditional implementation of the OFDM receiver causes signi?cant performance degradation. This letter proposes a subband superposed oversampled OFDM (SS-OOFDM) scheme for accommodating the diverse scenarios, including the scenarios with high mobility. To track the fast-varying mobile channel, a time-domain channel estimation method is developed to ?rstly obtain the channel impulse response (CIR) values at pilots by means of the basis expansion model. Subsequently, by utilizing Slepian sequences-based interpolation, the CIR values at data symbols are reconstructed. Furthermore, we design a subband decision feedback and feedforward equalizer (SDFFE) for exploiting the Doppler and multipath diversity gains. Simulation results show that the SS-OOFDM, especially in high-speed mobile channels, outperforms the traditional OFDM receiver in terms of the bit-error-rate (BER) performance.
关键词： Mobile Channel,SS-OOFDM,OFDM,Channel Estimation and Equalization,Long Term Evolution (LTE)
更新于2025-09-10 09:29:36
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Hybrid Precoding with Partially Connected Structure for mmWave Massive MIMO OFDM: A Parallel Framework and Feasibility Analysis
摘要： Hybrid precoding, a combination of digital and analog precoding, is an alternative to traditional precoding methods in massive MIMO systems with large number of antenna elements and has shown promising results recently. In this work, we implement a parallel framework to make hybrid precoding competitive in fast-fading environments. A low-complexity algorithm which exploits the block diagonal phase only nature of the analog precoder in a partially connected structure is proposed to arrive at a hybrid precoding solution for a multi-carrier single-user system using orthogonal frequency division multiplexing (OFDM). The original problem is broken down into two subproblems of finding the magnitude and the phase components which are solved independently. A per-RF chain power constraint is introduced instead of the sum power constraint over all antennas which is much more practical in real systems. An alternating version of the same algorithm is proposed for increased spectral-efficiency gains. Complexity and run-time analysis demonstrate the advantage of the proposed algorithm over existing hybrid precoding schemes for partially connected structure in an OFDM setting. Simulation results reveal certain insights about the partially connected structure and the trade-offs that have to be made to make it workable in a real wideband system.
关键词： partially connected structure,mmWave,massive MIMO,per-RF chain power constraint,Hybrid precoding,OFDM
更新于2025-09-10 09:29:36
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Optical Performance Monitoring Systems in Disaggregated Optical Networks
摘要： In this paper, optical performance monitoring is presented as enabler to address the key challenges in disaggregated optical networks. In fact, data plane elements for non-intrusive monitoring of different modulation formats will be discussed, reviewing different options based on high resolution spectral analysis. Furthermore, we will report how the information retrieved by these monitoring probes can be used to actually control the transceivers and other data plane elements, emphasizing on the suitable ?gures of merit to be delivered to the SDN control, orchestration and management planes.
关键词： disaggregated optical networks,optical OFDM,Optical performance monitoring
更新于2025-09-10 09:29:36
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Performance analysis of DST-based Intensity modulated/direct detection (IM/DD) systems for VLC
摘要： The dual functionality of assuring ‘illumination’ and ‘communication’ contemporaneously by relying on sustainable and energy-efficient opto-electronic devices like Light Emitting Diodes (LEDs) has enabled Visible Light Communication (VLC) to garner the attraction of research era. This work proposes a discrete sine transform (DST)-based optical OFDM system bestowing as the simplest and alternative multicarrier scheme complying the requirements of intensity modulated (IM) and direct detection (DD) systems. Moreover, this work addresses the most vital issue like peak to average power ratio (PAPR) which emerges principally due to the limited dynamic range of LEDs when exploiting DC-biased optical OFDM (DCO-OFDM). Therefore, this work imparts DST spreading to DST-based DCO-OFDM (DST-S-DCO-OFDM) and consequently, the PAPR performance is compared with other PAPR reduction schemes for the same system. Furthermore, in order to serve multiple subscribers with high data rates as well as to significantly reduce the amount of PAPR of the multicarrier system, this work investigates a DST-based single carrier frequency division multiple access (DST-SC-FDMA) and derives the mathematical analysis of the time-domain signal formats for different subcarrier mapping strategies like DST-based optical interleaved frequency division multiple access (DST-OIFDMA) and optical localized frequency division multiple access (DST-OLFDMA). The simulated results evidences that the reduction in PAPR for DST-S-DCO-OFDM is more predominant when compared with other PAPR reduction schemes and among the multiple access schemes, DST-OIFDMA is more power efficient upon comparison with DST-OLFDMA. However, both the schemes exhibit a significant reduction in PAPR when compared with DST-based optical orthogonal frequency division multiple access (DST-OOFDMA).
关键词： DST-SC-FDMA,VLC,DST-DCO-OFDM,DST-OIFDMA,DST-OOFDMA,DST-OLFDMA,PAPR
更新于2025-09-10 09:29:36
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Digital Domain Power Division Multiplexed Dual Polarization Coherent Optical OFDM Transmission
摘要： Capacity is the eternal pursuit for communication systems due to the overwhelming demand of bandwidth hungry applications. As the backbone infrastructure of modern communication networks, the optical fiber transmission system undergoes a significant capacity growth over decades by exploiting available physical dimensions (time, frequency, quadrature, polarization and space) of the optical carrier for multiplexing. For each dimension, stringent orthogonality must be guaranteed for perfect separation of independent multiplexed signals. To catch up with the ever-increasing capacity requirement, it is therefore interesting and important to develop new multiplexing methodologies relaxing the orthogonal constraint thus achieving better spectral efficiency and more flexibility of frequency reuse. Inspired by the idea of non-orthogonal multiple access (NOMA) scheme, here we propose a digital domain power division multiplexed (PDM) transmission technology which is fully compatible with current dual polarization (DP) coherent optical communication system. The coherent optical orthogonal frequency division multiplexing (CO-OFDM) modulation has been employed owing to its great superiority on high spectral efficiency, flexible coding, ease of channel estimation and robustness against fiber dispersion. And a PDM-DP-CO-OFDM system has been theoretically and experimentally demonstrated with 100 Gb/s wavelength division multiplexing (WDM) transmission over 1440 km standard single mode fibers (SSMFs).
关键词： spectral efficiency,digital domain power division multiplexing,non-orthogonal multiple access,coherent optical OFDM,optical fiber transmission
更新于2025-09-10 09:29:36
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Indoor visible light positioning combined with ellipse-based ACO-OFDM
摘要： Visible light communications have recently gained increasing attention as it is appealing for a wide range of applications such as indoor positioning. However, the light-emitting diode-based indoor positioning systems suffer from multipath distortion inside a room, leading to high positioning error. In order to mitigate the effect of multipath distortion of the optical channel, an indoor visible light positioning algorithm combined with ellipse-based asymmetrically clipped optical orthogonal frequency division multiplexing (ACO-OFDM) is proposed in this study, wherein the real-valued output of orthogonal frequency division multiplexing is modulated onto an ellipse, and only the imaginary value from the complex point on the ellipse is transmitted. Moreover, a received-signal-strength technique is used to determine the location of the receiver, and the Trust- region technique is employed to realise the 3D positioning. Simulation results demonstrate that this proposed algorithm can achieve high positioning accuracy, and the impact of different system parameters on the positioning accuracy is further investigated compared with the systems based on ACO-OFDM.
关键词： indoor positioning,ellipse-based modulation,Trust-region technique,ACO-OFDM,visible light communications,multipath distortion,RSS technique
更新于2025-09-10 09:29:36
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An Overview of OFDM-Based Visible Light Communication Systems From the Perspective of Energy Efficiency Versus Spectral Efficiency
摘要： In this paper, the energy ef?ciency and the spectral ef?ciency for orthogonal frequency division multiplexing (OFDM)-based visible light communication schemes are studied, which is crucial for practical application with limited energy resources. The conventional schemes, including asymmetrically clipped optical OFDM (ACO-OFDM), pulse-amplitude-modulated discrete multitone, and direct current biased optical OFDM, are compared in terms of energy ef?ciency and spectral ef?ciency relationship. The in?uence of power allocation for asymmetrically clipped dc biased optical OFDM and hybrid ACO-OFDM is also investigated. The energy ef?ciency and spectral ef?ciency of layered ACO-OFDM with a variable layer number are calculated and their relationship is also formulated. These conventional and hybrid modulation schemes are analyzed and compared through computer simulations, which should be considered in practice according to the requirements of illumination and transmission.
关键词： visible light communication (VLC),spectral ef?ciency,orthogonal frequency division multiplexing (OFDM),Energy ef?ciency
更新于2025-09-09 09:28:46
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[IEEE 2018 20th International Conference on Transparent Optical Networks (ICTON) - Bucharest (2018.7.1-2018.7.5)] 2018 20th International Conference on Transparent Optical Networks (ICTON) - Planning of Resilient OFDM-PON in Support of 5G Backhaul
摘要： Orthogonal Frequency Division Multiplexing Passive Optical Network (OFDM-PON) has been regarded as one of the promising solutions for 5G backhaul due to its excellence in spectral efficiency and transmission stability. However, the vulnerability of OFDM-PON to link failure cumbers its applicability in 5G backhaul, which is expected to offer enhanced network resilience. Although link duplication has evolved as a common practice for the protection of PON against link failure, the compromise between economical cost for backup links and QoS guarantee remains an open issue. In this paper, we focus on the network planning of resilient OFDM-PON and propose a novel backup mechanism to effectively mediate between network redundancy cost and performance degradation at both PHY and MAC layers.
关键词： OFDM-PON,resilient planning,optical backhaul
更新于2025-09-09 09:28:46