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The capacity of single-mode fiber links with direct-modulation/direct-detection is limited by the fiber dispersion and laser chirp. which lead to frequency selective fading at the receiver. In such transmission channels, the capacity can be improved by adaptively modulated optical OFDM. In this paper, we discuss the capacity limits of such links using adaptively modulated optical OFDM both in theory...
This work investigates the problem of extending the lifetime of dynamic WSNs with energy-harvesting (EH) sensors to enhancing the total WSN lifetime. This problem is modeled as finding the maximal number of covers each of which can cover all targets to be monitored. Since the concerned problem is also NP-complete, this work proposes a novel harmony search algorithm. By simulation, the proposed algorithm...
In this paper, we propose a hybrid time-frequency domain chaotic interleaving technique for physical-layer security enhancement in orthogonal frequency division multiplexing-based passive optical network (OFDM-PON) systems. The chaotic interleaving is performed by using the discrete Baker map, which is controlled by a Henon map. The initial values and the iteration parameter of the Henon map are used...
In this paper, we propose a matrix completion algorithm to acquire the sensor map of Internet of Things (IoT) network. Our approach consists of two main steps to reconstruct Euclidean distance matrix. Firstly, we formulate the Euclidean distance matrix completion problem as an unconstrained optimization in smooth Riemannian manifold. We next employ nonlinear conjugate gradient algorithm on this manifold...
Locally repairable codes (LRCs) are a family of erasure codes which have been proposed for data storage in distributed storage systems recently. For an LRC, a code symbol is said to have locality r and availability t, or (r, t)-locality, if the code symbol can be repaired respectively by t disjoint groups of other symbols, each of which has size at most r. For [n, k, d] LRCs with length n, dimension...
Carrier synchoronization is an important propblem in digital communications, not only in Nyquist signaling system but also in the faster-than-Nyquist (FTN) signaling system. For filling this gap, we propose a new non-data aided (NDA) frequency-offset estimation scheme for FTN signaling system. Combining discrete Fourier transform (DFT) with chirp z-transform (CZT), the proposed scheme can realize...
We experimentally demonstrate a self-homodyne transmission system over 10-km few-mode fiber by transmitting pilot tone and signal in different modes simultaneously. A data rate of 156 Gb/s for 16-QAM and 234 Gb/s for 64-QAM self-homodyne detection few-mode fiber transmission system is experimentally demonstrated by transmitting pilot tone and data signal at individual modes. No frequency offset and...
In this paper, a new orthogonal frequency-division multiplexing (OFDM) modulation based on phased-array is proposed for wireless physical layer security. By applying distinct initial phases for different subcarriers of the OFDM symbols, the transmitted information will be angle-range-dependent. Numerical results show that, the OFDM symbols are well preserved in the desired location, while these symbols...
We propose a scheme of optical duobinary (ODB) modulated upstream transmission system for reflective semiconductor optical amplifier(RSOA)-based colorless optical network units (ONUs) in 10-Gbps wavelength-division multiplexed passive optical network (WDM-PON), where a binary intensity modulation direct detection (IM-DD) receiver is used for cost-effectiveness and a fiber Bragg grating (FBG) is adopted...
In this paper, a cost-effective coherent PON is proposed using heterodyne detection of PDM-PAM-n signal. Flexible scheduling is achieved by DSP-enabled rate and loss budget adaption, which is experimentally demonstrated by transmission of PAM-2/3/4 signal at 2.5-GBaud/s rate.
This paper studies downlink resource allocation to improve user experience in ultra-dense small cell networks, which is characterized by multi-dimensional heterogeneities in terms of spectrum, cells, and user requirements. Specifically, spectrum access, power allocation, and user scheduling of small cells, are jointly investigated and an optimization problem is formulated, with the objective of maximizing...
In this paper, we propose a new definition of the energy efficiency (EE) for indoor visible light communication (VLC) systems and further investigate the tradeoff between the EE and spectral efficiency (SE). Different from the conventional concept of the EE in wireless communication systems, the newly defined EE in VLC systems utilizes the optical communication power instead of radio frequency power...
This paper presents a design and an implementation of a wideband autonomous cognitive radio (WACR) for anti-jamming. The proposed anti-jamming scheme is aimed at evading a jammer that sweeps across the whole wideband spectrum range in which the WACR is expected to operate. The WACR makes use of its spectrum knowledge acquisition ability to detect and identify the location of the sweeping jammer. This...
The rise of data traffic is a main trend in today's mobile networks but increases the power consumption as a price. In this paper, we aim to optimize the power consumption of downlink multi-user small-cell networks (SCNs) taking the quality of service (QoS) requirements of all the users into account. First we use semi-definite relaxation technique to transform the power consumption optimization problem...
A physical-enhanced secure wavelength division multiplexing chaos communication scheme in virtue of the chaos synchronization of two multimode semiconductor lasers (MSLs) is introduced. In this scheme, the messages are divided into a set of blocks, and these blocks are transmitted by different modes with different wavelengths, according to a pre-negotiated pattern. The numerical results indicate that...
Eye gaze means either the gaze direction or the distance between the pupil and fixed points such as canthus or glint inside pupil. Eye-Tracking aims to record the relative offsets of this distance as time goes by. For eye-tracking, to guarantee the precision of eye glint detection and location is really important. An accurate glint detection and location algorithm based on Harris corner detection...
It is challenging for the base station (BS) to serve multiple cell-edge users concurrently with data rate guarantee due to limited power and spectrum resource. Using the relay enhances cell-edge user received signal strength by short-distance communication in low transmit power. Non-orthogonal multiple access (NOMA), a promising spectral efficient technology for the 5-th generation network (5G), enables...
The sum-rate of the uplink multiuser massive multiple-input multiple-output (MIMO) system is investigated. For the considered massive MIMO systems, the base station (BS) is equipped with a large number of antennas, which are assembled into several sub-arrays. Meanwhile, in each of the sub-arrays, antennas are densely installed. With the analysis of the sum-rate, we find that, for given total number...
Perfect channel state information (CSI) is essential for precoding and combining in millimeter wave (mmWave) systems. The CSI estimation algorithm based on adaptive compressed sensing (CS) is an efficient method. However, the imperfect multi-resolution hierarchical codebook design possibly leads to wrong detections of angle of arrival (AoA) and angle of departure (AoD), which has a negative effect...
This paper investigates into multihop selective OFDM full duplex relaying (FDR), where M — 1 clusters of relays are connected in cascade to forward the information from the source to the destination. Due to imperfect isolation or cancellation, the self-interference (SI) is inevitable and should be taken into account. A closed-form expression for the outage probability is derived. Simulations are carried...
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