Automatic estimation and removal of noise on digital image

An spatially adaptive noise detection and removal algorithm is proposed.Under the assumption that an observed image and its additive noise have Gaussian distribution,the noise parameters are estimated with local statistics from an observed degraded image,and the parameters are used to define the constraints on the noise detection process.In addition,an adaptive low-pass filter having a variable filter window defined by the constraints on noise detection is used to control the degree of smoothness of the reconstructed image.Experimental results demonstrate the capability of the proposed algorithm.

Carrier Frequency Offset Estimation for FM and Symbiotic FM Radio Data System Hybrid Signal

The symbiotic FM radio data system(SRDS)is a radio data system that a specially designed OFDM signal co-lives with FM signal,which enables a significantly higher data rate than existing radio data systems.The cyclic prefix of the OFDM symbol has the same length as the OFDM body,which enables the analytic separation of the co-channel OFDM and FM signal at receiver side,utilizing the fact that the OFDM body and prefix is equal.In this work,we show that the OFDM body and prefix cannot be viewed as equal when there is sufficient carrier frequency offset(CFO).Thus,we propose a two-step CFO estimation algorithm for FM and SRDS hybrid signal.The first step estimates the coarse CFO by exploring the characteristics of the FM signal.Once the coarse CFO is removed,the residual CFO is small enough for FM and OFDM separation.The second step fine estimates CFO from the OFDM-only signal using its repeated PN structure after the separation.Detailed mathematical equations are formulated and simulation results are given.The results show that the proposed algorithm works fine with the simulation setup and has a final residual CFO less than 3.9Hz.

The Realization and Working Conditions of Memristor Based on Multisim

An equivalent circuit is realized using Multisim software by transforming a kind of circuit element according to Mapping principle and circuit theory. The effects of every parameter on the equivalent circuit are analyzed and the working conditions of the equivalent circuit are concluded by simulation.

Blind Image Quality Assessment by Pairwise Ranking Image Series

Image quality assessment(IQA)is constantly innovating,but there are still three types of stickers that have not been resolved:the“content sticker”-limitation of training set,the“annotation sticker”-subjective instability in opinion scores and the“distortion sticker”-disordered distortion settings.In this paper,a No-Reference Image Quality Assessment(NR IQA)approach is proposed to deal with the problems.For“content sticker”,we introduce the idea of pairwise comparison and generate a largescale ranking set to pre-train the network;For“annotation sticker”,the absolute noise-containing subjective scores are transformed into ranking comparison results,and we design an indirect unsupervised regression based on EigenValue Decomposition(EVD);For“distortion sticker”,we propose a perception-based distortion classification method,which makes the distortion types clear and refined.Experiments have proved that our NR IQA approach Experiments show that the algorithm performs well and has good generalization ability.Furthermore,the proposed perception based distortion classification method would be able to provide insights on how the visual related studies may be developed and to broaden our understanding of human visual system.

Network traffic prediction by a wavelet-based combined model

Network traffic prediction models can be grouped into two types, single models and combined ones. Combined models integrate several single models and thus can improve prediction accuracy. Based on wavelet transform, grey theory, and chaos theory, this paper proposes a novel combined model, wavelet-grey-chaos （WGC）, for network traffic prediction. In the WGC model, we develop a time series decomposition method without the boundary problem by modifying the standard à trous algorithm, decompose the network traffic into two parts, the residual part and the burst part to alleviate the accumulated error problem, and employ the grey model GM（1,1） and chaos model to predict the residual part and the burst part respectively. Simulation results on real network traffic show that the WGC model does improve prediction accuracy.

Performance analysis of ARQ schemes with code combining over Nakagami-m fading channel

This article investigates the performance of hybrid automatic repeat request （HARQ） with code combining over the ideally interleaved Nakagami-m fading channel. Two retransmission protocols with coherent equal gain code combining are adopted, where the entire frame and several selected portions of the frame are repeated in protocols I and II, respectively. Protocol II could be viewed as a generalization of the recently proposed reliability-based HARQ. To facilitate performance analysis, an approximation of the product of two independent Nakagami-m distributed random variables is first developed. Then the approximate analysis is utilized to obtain exact frame error probability （FEP） for protocol I, and the upper bound of the FEP for protocol II. Furthermore, the throughput performance of both two protocols is presented. Simulation results show the reliability of the theoretical analysis, where protocol II outperforms protocol I in the throughput performance due to the reduced amount of transmitted information.

Performance analysis of cooperative diversity for two-way multi-relay system with channel estimation error

In this work, we consider an amplify-and-forward two-way multi-relay system for wireless communication and mvesngate me effect of channel estimation error on the error rate performance. With the derivation of effective signal-to-noise ratio at the transceiver and its probability density function, we can get approximate expression for average bit error rate. Simulation results are performed to verify the analytical results.

Feedback threshold with guaranteed QoS in multiuser OFDM systems

A threshold setting scheme is proposed based on the resource management and limited feedback theory in multiuser orthogonal frequency division multiplexing （OFDM） systems. In adaptive resource allocation, the factors denoting the quality of service （QoS） and fairness are both considered as the user weight. From the aspect of feedback outage probability, the proposed algorithm sets the threshold for each user related to its weight, which brings enough feedback to the user with greater weight. Analysis and simulation results show that, compared with the threshold ignoring weights, the proposed scheme has much lower feedback load while with better QoS.

Channel estimation based on distributed compressed sensing in amplify-and-forward relay networks

In orthogonal frequency-division multiplexing （OFDM） amplify-and-forward （AF） relay networks,in order to exploit diversity gains over frequency-selective fading channels,the receiver needs to acquire the knowledge of channel state information （CSI）.In this article,based on the recent methodology of distributed compressed sensing （DCS）,a novel channel estimation scheme is proposed.The joint sparsity model 2 （JSM-2） in DCS theory and simultaneous orthogonal matching pursuit （SOMP） are both introduced to improve the estimation performance and increase the spectral efficiency.Simulation results show that compared with current compressed sensing （CS） methods,the estimation error of our scheme is reduced dramatically in high SNR region while the pilot number is still kept small.

WPANFIS:combine fuzzy neural network with multiresolution for network traffic prediction

A novel methodology for prediction of network traffic, WPANFIS, which relies on wavelet packet transform （WPT） for multi-resolution analysis and adaptive neuro-fuzzy inference system （ANFIS） is proposed in this article. The widespread existence of self-similarity in network traffic has been demonstrated in earlier studies, which exhibits both long range dependence （LRD） and short range dependence （SRD）. Also, it has been shown that wavelet decomposition is an effective tool for LRD decorrelation. The new method uses WPT as extension of wavelet transform which can decoorrelate LRD and make more precisely partition in the high-frequency section of the original traffic. Then ANFIS which can extract useful information from the original traffic is implemented in this study for better prediction performance of each decomposed non-stationary wavelet coefficients. Simulation results show that the proposed WPANFIS can achieve high prediction accuracy in real network traffic environment.

Coded overlapped code division multiplexing system with Turbo product structure

Coded overlapped code division multiplexing system with Turbo product structure （TPC-OVCDM） is introduced, and trellis coded modulation （TCM） code is employed as error correcting code for uncoded overlapped code division multiplexing （OVCDM） system. In such a scheme, row code and column code are TCM and OVCDM spreading code, respectively. Data bits are only encoded directly by TCM and transformed into a matrix. Each column of this matrix is then permuted by symbol interleaver before being encoded by OVCDM spreading code. During iterative decoding process in the receiver, two constituent decoders use symbol by symbol BCJR algorithm in the log domain. The order of decoding two sub-codes is determined by the encoding order. The proportion of TCM coding and OVCDM coding affects system performance. For fixed coding structure and symbol interleaver, the performance of TPC-OVCDM systems of different proportions of additive white Gaussian noise （AWGN） channel have been simulated. The results show that TPC-OVCDM system of reasonable proportion can achieve significant coding gain, compared with uncoded OVCDM system under the condition of same spectral efficiency at bit error rate （BER） level of 10^-5.

Variable length dynamic addressing based on network traffic distribution in wireless sensor networks

In this paper,a novel dynamic addressing scheme for wireless sensor networks(WSNs)is proposed by using variable length coding.A WSN is typically composed of numerous tiny energy-constrained sensor nodes with limited information processing and data storage capabilities;thus,the energy-efficient strategy is the key issue in designing protocols for WSN.Traditional addressing strategies adopt flat addressing(static and uniform addresses)for sensor nodes.However,the proposed variable length dynamic addressing(VLDA)for sensor nodes is based on the fact that different nodes in the network have uneven traffic loads.Therefore,nodes with more data to receive or send are allocated with shorter addresses.Whether a node is busy or not is determined by the network traffic distribution(NTD),which is defined as the number of data packets each node has received or sent in a period of time.Sensor nodes’energy is saved by VLDA scheme;hence,the wireless sensor network’s lifetime is extended.In the simulation,a 20%improvement has been achieved through the addressing scheme compared to traditional flat addressing.

Load-adaptive frequency reuse scheme for inter-cell interference coordination in relay networks

Cellular relay networks adopting orthogonal frequency division multiple （OFDM） technology has been widely accepted for next generation wireless communication due to its advantage in enlarging coverage scale as well as improving data rate.In order to improve the performance of user equipments （UEs） near the cell edge,especially to avoid the interference from inter-cell and intra cell,an enhanced soft frequency reuse scheme is adopted in this paper to assure inter-cell interference coordination （ICIC）.Compared with traditional frequency allocation work,the proposed scheme is interference-aware and load-adaptive,which dynamically assigns available frequency among UEs under certain schedule method in variable traffic load condition and mitigates interference using information provided by interference indicator.It can improve signal-to-interference plus noise ratio （SINR） of the UE in each sub channel thus enable the system achieve better throughput and blocking probability performance.Simulation results prove that the proposed scheme may achieve desirable performance on throughput,blocking probability and spectral utilization in the sector under different traffic load compared with other schemes.