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Optical Multi-Input and Multi-Output (O-MIMO) is considered as an effective solution in order to achieve high performance for Visible Light Communication (VLC) systems. However, O-MIMO systems are faced with the impact of Inter-Channel Interference (ICI) which results in system performance decrease. In this paper, a novel Index-based Optical Spatial Modulation (IOSM) is proposed to remove ICI and...
DHT-based file backup systems can provide efficient mechanisms for resource placement and lookup. However, these systems must deal with irregular and frequent join/leave of nodes and the problem of load unbalancing between nodes. This paper presents an efficient file replication scheme based on DHT identifier space clustering in order to guarantee data availability and support load balancing for DHT-based...
In this paper, a new physical-layer network coding (PNC) scheme is proposed for multiple-input multiple-output two-way relay networks where all network nodes, including two terminal nodes and the relay node, are equipped with multiple antennas. Spatial division multiplexing (SDM) technique is used at the two source nodes to increase transmission rate while the physical-layer network coding based on...
A Frequency Reuse algorithm which divides the users into two groups called Cell-Center Users (CCUs) and Cell-Edge Users (CEUs) is one of the most effective techniques that can mitigate the InterCell Interference as well as improve the spectrum efficiency in cellular networks. In literature, most of work on Strict Frequency Reuse algorithms in a Spatial Point Poisson network assumed that the reuse...
The development of network services makes their requirements for bandwidth become higher and more various, which leads to difficulty in Quality of Service (QoS) guarantee. In this paper, an OpenFlow switch featuring Weighted Fair Queuing (WFQ) algorithm is proposed. The system is implemented into NetFPGA 1G board which utilizes Xilinx Virtex II Pro 50 technology. The results have shown that our circuit...
We present an online boundary classification error detection algorithm to improve accuracy of the original distributed boundary detection algorithm for networked multirobot systems. It is a fully decentralized method based on the geometric approach allowing to suppress boundary errors without recursive process and global synchronization. The accuracy of the ration of correctly identified robots over...
This paper deals with the phase control for Neurospora circadian rhythm. The nonlinear control, given by tuning the parameters (considered as controlled variables) in Neurospora dynamical model, allows the circadian rhythms tracking a reference one. When there are many parameters (e.g. 3 parameters in this paper) and their values are unknown, the adaptive control law reveals its weakness since the...
Cyclically-coupled quasi-cyclic LDPC (CC-QC-LDPC) block codes have been shown to achieve outstanding bit error performance with extremely low error floor. In this paper, we propose two new types of CC-QC-LDPC block codes which can achieve a larger girth. We present the error performance of the CC-QC-LDPC codes constructed by the new mechanism. We show that with similar codelengths, the new codes outperform...
In this paper, we consider a cognitive two-way relay system with multiple relay nodes and multiple primary receivers over Nakagami-m fading channels. Relay nodes process signal following selective decode-and-forward (DF) relay technique. The opportunistic relay selection is used to choose the best relay. We derive the exact closed-form expression of the overall outage probability over Nakagami-m fading...
Due to the strong influence of the ambient noise and the time variation of underwater acoustic (UWA) channels with a large Doppler frequency shift, the time synchronization is a challenging issue in UWA-OFDM systems. In addition, the signal bandwidth of UWA communication systems is very limited. Thus, optimizing the bandwidth efficiency of the system is also an important target in designing synchronization...
We studied the performance of a next-generation mobile backhaul network that is based on a hybrid architecture employing NG-PON2 (TWDM-PON) and FSO technologies. We have developed a mathematical model of the downlink system. We then comprehensively analyzed the performance of TWDM-PON/FSO-hybrid backhaul downlink while considering the impacts of various physical layer impairments of both optical fiber...
The primary design goal in cellular technology is to provide high data rate services to its customers while still maintaining energy-efficient transmission over the network. The road to move forward is through deployment of highly densified network topologies. The emergence of these network topologies has also opened up research opportunities on how to exploit their physical layer (PHY) characteristics...
Visible Light Communication(VLC) has been considered as a potential access option for 5G wireless systems to solve performance limitation due to bandwidth shortage at radio frequency (RF) band. In (VLC) system, illumination infrastructure has dual usage at the same time namely illumination and wireless data transmission. DC Biased optical (DCO)-OFDM has been proposed for VLC systems to provide optically...
All operations of the information processing on computer relate to text editor. The misspellings or typing errors often make in text editor. In MS Office applications have English spellchecking function. The current Vietnamese spellchecking methods are mostly based on Vietnamese vocabulary corpus because most words are presented in these corpus. Currently, the Ede vocabulary corpus is also being gradually...
Document Classification has attracted several attentions from researchers due to the increase of digital form documents and the need of these documents' organization. One of the most popular approaches to deal with this problem is based on machine learning techniques [1]. However, the result of classification much depends on the linguistic preprocess and the document representation. The dependence...
Spectrum Sensing (SS) techniques play an important role in the Cognitive Radio (CR) systems. In recent years, many spectrum sensing techniques have been proposed in the literature to identify the state of the Primary Users (PUs) in the temporal domain. However, these techniques are usually interested in the current state of channel without consideration to their status in the past. In this paper,...
Density tapered array has a feature of having uniform excitations in all array elements. Then, a feeding network becomes very simple and array antenna will be applied for multi frequency operations. In this paper, a MATLAB program of achieving arbitrary density tapered distributions is developed. For example, the density distribution of cosine on a pedestal is designed. Moreover, radiation patterns...
Space shift keying (SSK) is a technique where the antenna indices are used to transfer the information. In this paper, we investigate optical SSK (OSSK) system under the combined effects of atmospheric turbulence (AT) and pointing error (PE). We introduce an analytical framework to obtain average pair-wise error probability and average bit error rate of OSSK scheme. It is observed that for small PE...
Communication systems subjected to strong impulse noise are prone to performance degradation when the impulse occurrence is neglected in the decoding process: turbo decoders are likely to exhibit error propagation because the decision-making is dictated by excessive samples corrupted by impulses when the conventional decision metric, which is based on the assumption of additive white Gaussian noise,...
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