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This paper proposes a new method to improve re performance of intra-field interpolation which is the mos~ important element of deinterlacing method. Traditional edge- based methods were poor at determining accurate edge iirection which decides interpolation performance. The 7roposed method decides the direction and slope of edge based on locally adaptive-thresholded binary image to mprove efficiency and accuracy, and it also increased the ~orizontal size of search window to 15 for better direction ietermination at gentle slope. Compared to traditional edge- based methods, interpolation based on binary image, which is ,`enerated using the proposed method, leads to great erformance improvement. With computer simulations for a ~`ariety of images, this paper shows the new approach is much ~etter than traditional methods.. [ABSTRACT FROM AUTHOR]

This paper presents an implementation of an ~daptive beamformer in a hands-free unit. The proposec~ ~daptive beamformer suppresses stationary noise an~ nterference sound. The adaptive beamformer and acoustic `cho canceller were implemented in a compact hands-free mit with a low-cost DSP. Experimental results demonstrate he noise reduction performance of the hands-free unit'. [ABSTRACT FROM AUTHOR]

This paper describes a new coding method based on binary $(d,k)$ runlength constraints used for recording or transmitting an audio or video signal, computer data, etc. Data words of $m$ bits are translated into codewords of $n$ bits using a conversion table. The codewords satisfy a $(d,k)$ runlength constraint in which at least $d$ and not more than $k$ ‘0’s occur between consecutive ‘1’s. The $n$ -bit codewords alternate with $p$ -bit merging words which in the prior art are selected such that the $d$ and $k$ are satisfied at the borders of consecutive codewords. We present a new coding method, where the codewords obey the $(d,k)$ -constraint, but the merging words are not required to obey the $(d)$ -constraint. The merging word that satisfies said conditions, yielding the lowest low-frequency spectral content of the encoded signal obtained after modulo-2 integration, is selected. The spectral performance of the new coding method has been appraised by computer simulations for the EFM (Eight-to-Fourteen Modulation) parameters, $d=2, k=10$ , and $p=3$. The low-frequency content of the signal generated by the newly presented coding method is around 4 dB lower in the relevant low-frequency range than that generated by the conventional EFM method. [ABSTRACT FROM AUTHOR]

In this paper, a maximum likelihood (ML) unequal error protection (UEP) video streaming technique is proposed for WirelessMAN-Advanced systems that are equipped with multiple antennas. The assumed video compression method is H.264/AVC which is a commercially successful technique. ML signal detection is optimal in terms of packet error performance for multiple antenna systems. However, common wisdom is that the optimal ML detection cannot be used for an implementation of UEP which is important for video streaming. In this paper, it is shown that UEP can be implemented using the optimal ML detection. With the aid of computer simulations, the proposed ML-UEP technique is shown to improve video quality significantly compared to a recently proposed UEP technique that is based on the suboptimal signal detection QR-LRL. The PSNR improvement by the proposed method comes at the cost of increased computational complexity in the physical layer 1. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a binaural system for virtual auditory space synthesis and reproduction. We introduce a subjective listening test for head-related transfer function (HRTF) customization and real-time implementation of ambisonic surround sound over headphones. In this test, a listener first selects the closest-matching HRTF dataset from an existing database. The selected HRTF dataset must fulfill the criteria of front-back discrimination and up-down discrimination. Secondly, the selected HRTF dataset is utilized to build a binaural ambisonic system composed of an encoder for synthesizing multiple sound sources, an image-source model for listening-room simulation, an ambisonic rotator responding to head motion in three axes, and a binaural ambisonic decoder. Additionally, we propose a system optimization technique that minimizes computational cost and enhances audio quality. Finally, we present both subjective and objective measurements of the perceived audio quality that were conducted to validate this approach. The audio quality assessment examined the frequency hearing impairment, localization error, and localization blur. The proposed system is especially suitable for mixing and rendering immersive sound in virtual reality. [ABSTRACT FROM AUTHOR]

This paper presents an optimization algorithm that schedules the operations of household appliances to minimize the monthly electricity bill and maintain comfort for electricity consumers through the interaction between a home energy management system (HEMS) and consumers. In comparison with existing HEMS optimization algorithms over a single day time horizon without considering the monthly electricity bill, the novelty of the proposed method is that the monthly bill target preferred by the consumer is achieved through the optimal operation of appliances over a multi-day time horizon. A key part of the proposed approach is to relax the multi-day optimization problem by adding a penalty on the range of consumer preferred indoor temperature related to operation of the air conditioner, consequently leading to calculation of the desired monthly electricity bill. Simulation studies are illustrated with a single household and four households equipped with smart home appliances in time of use (TOU) and inclining block rate (IBR) pricing tariffs. The results demonstrate that the proposed method enables the total electricity cost and cumulative electricity consumption to successfully converge to each consumer?s target. Furthermore, the impacts of the penalty variable for the relaxed consumer thermal condition and the energy trade between households on the performance of the proposed algorithm are investigated. [ABSTRACT FROM AUTHOR]

This paper mainly deals with the statistical processing methods in wireless filed strength prediction process after sampling data are collected. The conventional standard for data collection and statistical processing in the prediction of wireless filed strength is Lee's criteria. It utilizes linear averaging to process sampling data, as many other related papers discussed. However, the accuracy of such first order moment estimation is low, especially under serious Rayleigh fading channels. As regards to the defects of the method, we propose four novel statistical processing methods to process the collected data for wireless field strength. Computer simulations and corresponding analysis verify its much better prediction results with small estimation variances. [ABSTRACT FROM AUTHOR]

This paper deals with a real-time image based relighting system for tangible video teleconference. The proposed image based relighting system renders the extracted human object using the virtual environmental images. The proposed system can homogenize virtually the lighting environments of remote users on the video teleconference, or render the humans like they are in the virtual places. To realize the video teleconference, the paper obtains the reflectance models of users in real-time using the controlled lighting system. The reflectance models of human surface are obtained by a pair of lighting sources which are turned on and off alternatively. The images with different illuminations are exploited to model the reflectance on the object surfaces. The environment map for rendering is acquired by the mirror ball images or virtual background ones. And the relighting algorithm is implemented by GPU based programming for real-time operation. According to the simulations, the proposed system estimates the reflectance models of human faces, and relights the human faces in real-time. The objects are rendered by the reflectance models and virtual environment map. The proposed system enables the users to immerse video teleconference just as they are in the virtual environments. [ABSTRACT FROM AUTHOR]

There have been many papers concerning about the Peak to Average Power Ratio (PAPR) reduction and High Power Amplifier (HPA) linearization techniques for wireless OFDM communication systems. Few papers, however, make deep analysis on the relation between these two techniques. Based on Saleh's memoryless Traveling Wave Tube Amplifier (TWTA) model, computer simulations and analysis in this paper demonstrates that, especially when the HPA is working near or in the saturation region, a predistorter will cease to be in effect. In such cases, PAPR reduction techniques may be resorted to help to improve the Adjacent Channel Interference (ACI), BER performances and HPA efficiency. [ABSTRACT FROM AUTHOR]

Though ubiquitous, the full potential of consumer electronic devices in the home, as content creators, remains underutilized due to the limited interaction between the consumers and the existing on-demand application and media services. Although services such as interactive television could change this, the geographic distribution of groups of consumers and the need for on-the-fly media processing that this entails, makes the efficient utilization of resources a complex optimization task requiring mechanisms to simultaneously allocate processing and network resources to groups of users. However, these technologies have not yet been developed, and brute force methods remain prohibitively complex. In order to overcome this problem, this paper proposes heuristic algorithms to both generate end-to-end delay bound multicast trees for individual groups of users and to co-locate multiple multicast trees, such that a minimum group quality metric can be satisfied. The performance of the proposed heuristic solution is evaluated in terms of the serving probability, i.e., the resource utilization efficiency, and computation time of the resource allocation decision making process. Simulation results show that improvements in the serving probability of up to 50%, in comparison with existing generic resource allocation schemes, and several orders of magnitude reduction of the computation time, in comparison to an optimal linear programming solution approach, can be achieved. [ABSTRACT FROM AUTHOR]

This paper proposes a novel Language Model (LM) adaptation method based on Minimum Discrimination Information (MDI). In the proposed method, a background LM is viewed as a discrete distribution and an adapted LM is built to be as close as possible to the background LM, while satisfying unigram constraint. This is due to the fact that there is a limited amount of domain corpus available for the adaptation of a natural language-based intelligent personal assistant system. Two unigram constraint estimation methods are proposed: one based on word frequency in the domain corpus, and one based on word similarity estimated from WordNet. In terms of the adapted LM's perplexity using word frequency in tiny domain corpora (ranging from 30~120 seconds in length) the relative performance improvements are measured at 13.9%~16.6%. Further relative performance improvements (1.5%~2.4%) are observed when WordNet is used to generate word similarities. These successes express an efficient ways for re-scaling and normalizing the conditional distribution, which uses an interpolation-based LM. [ABSTRACT FROM AUTHOR]

Depth map coding aims to maximize the perceived visual quality of the synthesized virtual views instead of the depth maps. Therefore, it is necessary to develop new synthesized view distortion model to capture the effect of depth map distortion on the final quality of the synthesized views. This paper proposes a structural similaritybased synthesized view distortion (SS-SVD) model to relate perceptual distortion in coded depth map and synthesized view by deriving the relationship between the depth map distortion, warping error and synthesized view distortion. The SS-SVD model is applied to the rate distortion optimization which describes the relationship between depth coding bitrate and synthesized view distortion for depth map coding mode selection. Experimental results show that the proposed SS-SVD method obtains both better rate distortion performance and perceptual quality of synthesized views than JM reference software. [ABSTRACT FROM AUTHOR]

Eye gaze tracking system has been widely researched for the replacement of the conventional computer interfaces such as the mouse and keyboard. In this paper, we propose the long range binocular eye gaze tracking system that works from 1.5 m to 2.5 m with allowing a head displacement in depth. The 3D position of the user's eye is obtained from the two wide angle cameras. A high resolution image of the eye is captured using the pan, tilt, and focus controlled narrow angle camera. The angles for maneuvering the pan and tilt motor are calculated by the proposed calibration method based on virtual camera model. The performance of the proposed calibration method is verified in terms of speed and convenience through the experiment. The narrow angle camera keeps tracking the eye while the user moves his head freely. The point-of-gaze (POG) of each eye onto the screen is calculated by using a 2D mapping based gaze estimation technique and the pupil center corneal reflection (PCCR) vector. PCCR vector modification method is applied to overcome the degradation in accuracy with displacements of the head in depth. The final POG is obtained by the average of the two POGs. Experimental results show that the proposed system robustly works for a large screen TV from 1.5 m to 2.5 m distance with displacements of the head in depth (+20 cm) and the average angular error is 0.69°. [ABSTRACT FROM AUTHOR]

Transcoding between Distributed Video Coding (DVC) and VC-1 is an interesting research topic, has various applications, and VC-1 is one of most popular and efficient video codecs. Among the various techniques related to transcoders, we focus on motion estimation and mode decision. In this paper, we propose a Best Matched Vector Selection (BMVS) and fast mode decision to increase the accuracy and speed of the motion vector estimation and mode decision in the transcoder. BMVS is used to predict motion vectors for multiple reference frames that are far from the current frame. The proposed mode decision scheme selects a mode for the current coding block based on the information transferred from the DVC decoder, without calculating the Rate-Distortion (RD) costs for all possible candidate modes. Simulation results show that the proposed schemes simplify the transcoder significantly without degrading the transcoded video sequences. [ABSTRACT FROM PUBLISHER]

In this paper, we propose orthogonal frequency division multiplexing (OFDM) receivers using oversampling, where the oversampling ratio is extended from integers to rational numbers. We propose several receiver structures, which reveal the same performance, with the same oversampling ratio. Since the low-pass filters in general OFDM receivers are not ideal, additional noise is introduced into the side bands of the demodulated signal. If we increase the sampling frequency above the symbol rate, subcarriers with higher frequencies than we want are obtained and composed of noise only. Removing the unwanted higher frequency components we can reduce the noise and obtain signal-to-noise power ratio gain compared to the conventional symbol rate receivers. Through computer simulations, we verify the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents an improved, scattered pilot synchronization (SPS) scheme in digital video broadcasting-handheld (DVB-H) systems, which detect the pilot pattern of the currently received orthogonal frequency division multiplexing (OFDM) symbol. To reduce the SPS time, and to mitigate the influence of the sampling frequency offcet (SFO), the proposed SPS method is based on the conventional correlation-based SPS, and adopts a partial correlation. By using computer simulations, the synchronization performances of the traditional SPS and the new proposed SPS algorithms are evaluated in terms of their probabilities of synchronization failure. [ABSTRACT FROM AUTHOR]

In this paper, a dual combining based decoding scheme is proposed to enhance the detection performance of space-time block coding with two transmit antennas in a highly time-varying mobile channel. The proposed scheme analyzes the signal-to-noise ratio and signal-to interference plus noise ratio of decision variables for a zero-forcing combiner (ZFC) and a matched filter combiner (MFC), respectively. Based on the analysis, we derive a sophisticated decoding scheme which utilizes tentative detection symbols of the ZFC based decoder to cancel inter-symbol interference from the decision variables of the MFC. Computer simulations show that the proposed scheme outperforms the conventional decoding scheme with the ZFC or the MFC. [ABSTRACT FROM AUTHOR]

In this paper, five novel schemes based on greedy algorithm are proposed to reduce the peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems. For each proposed scheme, a simple transformation is performed on the partial transmit sequences in an iterative fashion to lower the PAPR. Computer simulations results show that all the proposed schemes can achieve PAPR reductions, but the performances of the PAPR reduction are different. To further evaluate their PAPR reductions, we compare the proposed schemes with the iterative flipping scheme. The results show that when the number of subblocks is not large, some of the proposed schemes can offer better PAPR reduction performance than the iterative flipping scheme with comparable computational complexity. [ABSTRACT FROM AUTHOR]

As a loudspeaker's physical size decreases, its ability to reproduce low frequencies is hindered. In this paper we propose a method of creating virtual bass using an efficient frequency tracking algorithm. The proposed algorithm has low computational complexity but excellent performance. The results of computer simulations and subjective tests are presented to validate the algorithm. [ABSTRACT FROM AUTHOR]

In this paper, we investigate an advanced peak windowing method as a peak-to-average power ratio(PAPR) reduction technique in orthogonal frequency division multiplexing (OFDM) systems. The advanced peak windowing method is performed by introducing new weighting coefficients in case that successive peaks are generated within a half of the window length. Applying the new weighting coefficients, we can tightly limit the successive peaks to the given threshold level. Through a computer simulation, we verify that the BER performance improvement can be achieved by the proposed peak windowing method while maintaining almost the same complementary cumulative distribution function (CCDF) and spectral characteristics. [ABSTRACT FROM AUTHOR]

With the development of IEEE 802.11 MAC (Medium Access Control) protocols, efficient utilization of wireless local area networks (WLANs) has become a very important issue. In typical IEEE 802.1] networks, the association between mobile users (MUs) and access point (AP) is based on the signal strength information. As a result, it often results in the extremely unfair bandwidth allocation among MUs. In this paper, we propose a distributed association algorithm to achieve load balancing among the APs. The proposed algorithm gradually balances the AP loads for the available multiple bit rate choices in a distributed manner. We analyze the stability and overhead of the proposed algorithm, and show the improvement of the fairness via computer simulation. Additionally, we have implemented a prototype on a testbed to prove its feasibility. [ABSTRACT FROM AUTHOR]

The key assumption in all space-time block coded orthogonal frequency division multiplexing (OFDM) schemes is that the channel remains static within the whole codeword length. This will inevitably introduce an irreducible error floor, caused by the inter-transmit-antenna interference (ITAI), in the high signal-to-noise (SNR) region over the time selective fading channels. To mitigate the impact of ITAI, a novel signal detection scheme for four-transmit-antenna space-time-frequency coded OFDM system has been proposed in this paper. Through the theoretical analysis and computer simulations, it is proven that the proposed method can handle both slow and fast fading channels very effectively as well as efficiently, removing the error floor within the normal Doppler frequency range. [ABSTRACT FROM AUTHOR]

This paper studies a frequency offset estimation and compensation technique taking advantage of Complementary Code Keying (CCK) in a baseband architecture. The proposed technique can switch between coarse and fine frequency offset estimation subsystems in order to achieve lower estimation errors and lower bit-error rates (BERs). The architecture mainly exploits the specific characteristics of the CCK code set; thus it blindly extracts the frequency offset without any assistance from a training sequence. The proposed technique is very suitable to be employed in a CCK-based WLAN system for the purpose of increasing data transmission rate. Extensive computer simulations show that the proposed technique and its architecture realization exhibit superiority in overall system performance. [ABSTRACT FROM AUTHOR]

In this paper, we suggest a synchronization receiver for MIMO-OFDM based mobile broadcasting system. A MIMO-OFDM receiver with algorithms for tracking of residual frequency offset (RFO) and sampling frequency offset (SFO) is designed and simulated. The proposed synchronization and compensation schemes are applied to IEEE 802.16e WiMAX and its performance is investigated by computer simulations in terms of mean square error (MSE) and bit error rate (BER). The proposed RFO and SFO estimator has a fast convergence and a small residual degradation even for high speed mobile station. [ABSTRACT FROM AUTHOR]

In video transmission, the compressed signal is extremely vulnerable to bit errors. Error concealment is widely used in video decoder to recover corrupted frames. Due to the use of variable length codes (VLCs), a single bit error in block-based bitstream may propagate to following of this slice. Especially, the effectiveness of error concealment technique relies heavily on correctly locating errors. In this paper an error detector based on syntax and continuity which consists of two stages is proposed. The first stage is to find erroneous slice according to checking constraints imposed on video bitstream syntax or detecting special error patterns. In the second stage, the precise position of the first erroneous macroblock (MB) is found based on the continuity of spatial or temporal data of neighbor MBs. Simulation results demonstrate that the proposed method improves performance of error detection significantly compared with the traditional syntax-based method'. [ABSTRACT FROM AUTHOR]

In the encoder of the national television system committee (NTSC) system, a composite video burst signal (CVBS) is generated using the luminance (Y) signal and the quadrature amplitude modulation (QAM) modulated chrominance (C) signal. In the decoder, it is important that the CVBS be accurately separated into luminance and chrominance signals by a Y/C separation filter. Otherwise, various artifacts, such as dot crawl, rainbow effect, and color bleeding, appear in a decoded video, degrading the quality of the decoded video. In addition, modern high-definition television (HDTV) system suffers from outdated analog decoding artifacts when HDTV compression techniques were applied to the not ideally decoded former standard-definition format video images. This paper proposes artifact reduction methods of dot crawl and rainbow effect using the characteristics of the CVBS video. The proposed artifact reduction algorithms use two successive frames, in which the decoded video images are divided into not moving (stationary) and moving regions. The stationary regions are filtered by a temporal filter whereas the moving regions are further classified into three subdivided regions of different types of artifacts to apply them into temporal or spatial filters because inappropriately temporally filtered moving region delivers jitters on the edge. In the proposed algorithms, considering characteristics of the NTSC decoded image, a block matching algorithm based on 4×4 non-overlapping blocks is used for motion estimation and compensation. Computer simulations with various simulated and real videos containing NTSC artifacts show the effectiveness of the proposed artifact reduction methods. [ABSTRACT FROM AUTHOR]

This paper proposes an interpolation algorithm for conversion from the interlaced to the progressive scanning format. The proposed algorithm consists of two parts: an edge direction detection part and a fuzzy rule-based edge-restoration interpolation part. The different types of edge, peak, and monotonic slope patterns are considered in a spatial domain interpolation strategy. Edges with a certain vertical component look preserved in the interpolation using a fuzzy rule-based algorithm. The vertical resolution in the interpolated image is subjectively concealed by introducing vertical gradients in the interpolation. Computer simulations verify the effective performance of this image processing technology. [ABSTRACT FROM AUTHOR]

This paper proposes a noise-reduction method to improve the channel-estimation performance in Digital Video Broadcasting-Terrestrial (DVB-T) receivers. In DVB-T receivers, channel estimation is usually carried out in frequency domain using known symbols, referred to the pilot. A Least-squares (LS) estimator has been preferred for channel estimation due to the low complexity but it may be vulnerable to noise because it does not consider noise effect in obtaining its solution. To compensate for the weakness of the LS estimator, we propose an auto-regressive averaging method to average all estimated channel coefficients up to present time without the increase of system delay and complexity for DVB-T fixed receptions. Computer simulation shows that the proposed method improves the estimation performance in overall SNRs. [ABSTRACT FROM AUTHOR]

Wireless mesh networks are a suitable technology for wireless broadband home networks which can expand into ubiquitous networks. In this paper, we introduce a home network architecture which is based on the multihop wireless mesh networks and provide a general overview of the architecture. The system model introduced might be helpful to set up self-organizing and self-configuring network for consumer homes. The wireless mesh home network architecture can reduce the deployment cost and provide a much simpler deployment process by wireless home mesh routers. The home mesh routers provide various functions. Thus, home mesh router discovery and selection problems pose a primary challenge in the wireless mesh home network architecture. To deal with these problems, we propose a scoped-proactive home mesh router discovery scheme and a QoS-driven home mesh router selection mechanism. The scoped-proactive discovery protocol limits the flooding area. Among the candidates, a serving mesh router is selected based on a QoS-driven selection metric. Through simulations, we show that our schemes perform better than existing mechanisms in terms of various performance measures. [ABSTRACT FROM AUTHOR]

In mobile OFDM communication systems, Doppler spread leads to the loss of orthogonality between the sub-carriers, limiting the achievable throughput of the moving transceivers. In this paper, the effect of Doppler spread in Rayleigh fading channels is investigated, and a method of time-variant Doppler frequency estimation and compensation is proposed for mobile OFDM systems. Computer simulation results are included to support our development. [ABSTRACT FROM AUTHOR]

This paper presents a novel technique to compensate intermodulation distortion of a self-heterodyne direct conversion OFDM system in multipath propagation environments. A self-heterodyne direct conversion system has an advantage that simple receivers can be built that are completely immune to any phase noise or frequency offset. This system, however, has a disadvantage that the nonlinear detector at the receiver of the self-heterodyne direct conversion system gives rise to intermodulation distortion. In this study, channel estimation is performed using a training sequence and then the predistortion coefficients with regard to estimated channel parameters are derived to compensate the receiver nonlinearity. Transmit power allocation technique is employed to overcome multipath fading channels as well. Computer simulation demonstrates that the proposed approach improves BER performance of the self-heterodyne direct conversion system in a multipath fading channel. This scheme gives advantage to multi-carrier systems, such as OFDM, that are much more sensitive to frequency and phase error than single-carrier systems. [ABSTRACT FROM AUTHOR]

Orthogonal frequency division multiplexing (OFDM) has been used in many communication systems. However, the major drawback of OFDM system is high pea k- to-average-power ratio (PAPR). In this paper, we introduce low complexity phase weighting method to reduce PAPR of OFDM signals. Proposed method is derived from property of discrete Fourier Transform (DFT) of periodical sequences. PAPR can be reduced efficiently by phase weighting method with low complexity. The simulation results show the same PAPR reduction efficiency of proposed method in comparison with Partial Transmit Sequence (PTS) or sub-block phase weighting (SPW). The proposed technique can reduce 2.15dB of PAPR with two phase-factors and 3.95dB of PAPR with four phase-factors. The analysis on complexity presents remarkable improvement of low complexity phase weighting method. Proposed method odd case can save 75% and 8 7.5% number of multiplications of PTS method and SPW method separately. The other case of proposed method, even case, can save near 60% number of additions of PTS and over 70% of SPW. [ABSTRACT FROM AUTHOR]

The main disadvantage of OFDM systems is its sensitivity to carrier frequency offset (CFO) and timing offset. In this paper, an efficient method for estimating CFO is developed based on maximum likelihood principle, of which emphasis on the CFO ambiguity resolution. In this method, only one training symbol is required and the range of the CFO which can be handled is the overall transmission spectrum. Differential coding in frequency-domain is performed to estimate the integral part of CFO (IFO). When frequency- selective channel is present, a prior information of the statistic of the channel frequency response is used to eliminate its effect on estimation performance. Computer simulations are performed to show the superiority to the method available. [ABSTRACT FROM AUTHOR]

A novel scheme for space-time block coding with a variable transmit diversity gain is proposed for OFDM systems in the paper. The OFDM symbols are divided into two groups of orthogonal sub-symbols with each group coded in Alamouli STBC in the coding, and the new scheme for STBC is constructed by differently combining the coded data of each group with the different transmit diversity gain able to be achieved by linearly processing and correspondingly combining the received data on the sub- carriers. The proposed scheme is feasible to be used in video transmission and a new unequal error protection applied to MPEG- 4 video transmission is discussed. The results of computer simulation show that the proposed scheme has double diversity gain and quadruple diversity gain. The new unequal error protection scheme has a gain more than 8dB and higher efficiency than the UEP based on the RCPC codes. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel postprocessing technique based on the theory of the projection onto convex sets (POCS) in order to reduce the blocking artifacts in digital high definition television (HDTV) images. By detecting and eliminating the undesired high-frequency components, mainly caused by blocking artifacts, we propose a new smoothness constraint set (SCS) and its projection operator in the DCT domain. In addition, we propose an improved quantization constraint set (QCS) using the correlation of DCT coefficients between adjacent blocks. In the proposed technique, the range of the QCS is efficiently reduced as close to the original DCT coefficient as possible to yield better performance of the projection onto the QCS. Computer simulation results indicate that the proposed schemes perform better than conventional algorithms. Furthermore, we introduce a fast implementation method of the proposed algorithm. The conventional POCS-based postprocessing techniques require the forward/inverse discrete cosine transform (DCT/IDCT) operations with a heavy computational burden. To reduce the computational complexity we introduce a fast implementation method of the proposed algorithm that does not perform DCT/IDCT operations. Estimates of computation savings vary between 41% and 64% depending on the task. [ABSTRACT FROM AUTHOR]

To obtain a good tracking performance in an optical disk drive servo system, it is essential to attenuate periodic disturbances caused by eccentric rotation of the disk. As an effective control scheme for enhancing disturbance attenuation performance, disturbance observers (DOBs) have been successfully applied to the track-following servo system of optical disk drives. In disk drive systems, the improvement of data transfer rate has been achieved mainly by the increase of disk rotational speed, which leads to the increase of the disturbance frequency. Conventional DOBs are no longer effective in disk drive systems with a high-speed rotation mechanism because the performance of conventional DOBs is severely degraded as the disk rotational frequency increases. This paper proposes a new DOB structure for effective rejection of the disturbance in optical disk drives with a very high rotation speed. Asymptotic disturbance rejection is achieved by adopting a band-pass filter in the DOB structure, which is tuned based on the information on the disturbance frequency. In addition, performance sensitivity of the proposed DOB to changes in disk rotational frequency is analyzed. The effectiveness of the proposed DOB is verified through simulations and experiments using a DVD-ROM drive. [ABSTRACT FROM AUTHOR]

A true video-on-demand (TVOD) system lets users view any video program, at any time, and perform any VCR functions, but its per-user video delivery cost is too expensive. A near video-on-demand (NVOD) is a more scalable approach by batching multiple clients to a shared stream or broadcasting videos. In order to provide subscribers with a high-quality VOD service, it is desirable to add VCR functionality such as fast forward, fast backward and so on, but the existing video broadcasting, protocols have a limitation on providing VCR functionality. In this paper, we present the conditions necessary to provide VCR functions and then propose a video broadcasting scheme suitable for providing them, which satisfies these conditions, with minimal resource requirements. Since our proposed scheme receives video frames as a unit it can keep up rapidly with a changing VCR action pattern. It is demonstrated that the scheme provides VCR functionality consistently with minimal buffer space through simulations. [ABSTRACT FROM AUTHOR]

In this paper, we propose a power-efficient and QoS (Quality of Service) -aware MAC (Medium Access Control) scheduling algorithm for Bluetooth scatternet. If the inter-piconet scheduler in a bridge node between piconets operates simply by the Round Robin (RR) policy, a number of time slots may be wasted due to the guard time for piconet switching and the exchange of POLL-NULL packets. To overcome the link wastage problem in Bluetooth scatternet scheduling, several algorithms have recently been proposed. Although they can provide all of the links of a bridge node with fair service opportunities, they may cause waste of wireless resources since different Bluetooth devices may have various traffic characteristics. In addition, since Bluetooth devices are often required to operate under limited battery capacity, the number of unnecessary piconet switching has to be minimized for the power-efficient operation of a Bluetooth scatternet. Therefore, we propose a mechanism to support the power-efficient operation of a Bluetooth scatternet while guaranteeing various QoS requirements of Bluetooth devices. The proposed algorithm is compliant with the current Bluetooth specification, and we demonstrate its improved performance via simulations. [ABSTRACT FROM AUTHOR]

In this paper, a technique based on the auto correlation Junction is proposed to estimate the Doppler spread in Rayleigh fading channels for mobile OFDM systems. It is simply implemented with the cyclic structure of OFDM symbols, and any other additive data and pilots need not to be inserted into the common OFDM symbols. This algorithm can be applied directly to the OFDM system with transmit diversity (TD) and to MIMO OFDM systems. Computer simulation results are included to support our developments in the terms of mean estimation value and mean square error. [ABSTRACT FROM AUTHOR]

In this paper we consider the problem of estimating the impulse responses of loudspeakers. This is an important problem since loudspeaker impulse responses constitute a vital component in some signal processing applications such as correction of loudspeaker characteristics. Up to now the most accurate but also most expensive method has been to estimate the impulse responses from measurements taken in an anechoic chamber We present a method that allows good estimation of loudspeaker impulse responses in an ordinary echoic environment. This is accomplished by estimating the acoustic path of the room using a second loudspeaker with a known impulse response. Numerical simulations are carried out in order to study the performance of the suggested method. [ABSTRACT FROM AUTHOR]

The most attractive characteristic of the Gardner's method is the detected timing error is free from carrier offset of both arms of the transmitted complex signal are used. However, in VSB system, symbol information is mainly contained in I channel. Q channel is just a Hubert transform of I channel. In this reason, most VSB receivers only use I channel signal for symbol timing recovery. It works well when carrier offset does not exist or negligible, but get worse if not. This paper presents another timing recovery method that is suitable for VSB receivers. Simulations show that the proposed method provides consistent performance regardless of carrier recovery status and it can estimate the timing error even at symbol rate. [ABSTRACT FROM AUTHOR]

The robust reception of network parameters is a very important issue for the successful deployment of mobile infotainment services, particularly in fast-moving environments. An infrastructure broadcasts service access-related messages to consumer devices. These access messages critically affect the connectivity between the consumer devices and service providers. This paper proposes an algorithm to increase the connectivity by collaborating consumer devices to share access information messages. The consumer device that receives the access message retransmits the message by attached it to its beacon message. This is performed only when there are neighboring consumer devices that did not receive the message. This paper also proposes an extended beacon message for this purpose. The proposed algorithm was evaluated with computer simulations. [ABSTRACT FROM PUBLISHER]

With the spread of high-definition video devices, and with the advance of digital broadcasting systems and video portal services in the Internet domains, numerous highdefinition video presentations become available in everyday life. Under these circumstances, the desire of people to enjoy video contents in new ways had grown. This paper proposes a new multivision video provisioning system that enables numerous users to access any view area with any desired resolution interactively. The basic idea is that the partial area (tile)-based pre-coded video streams are stored in advance. These multiple streams are joined dynamically and delivered based on the user?s view-area position. In this paper, the details of H.264/AVC tile-based video coding and a fast tile stream joiner scheme are presented. Simulation experiments and our practical implementation demonstrate the feasibility and effectiveness of our proposal. [ABSTRACT FROM AUTHOR]

The recent proliferation of smart mobile devices with IEEE 802.11 interfaces for real-time multimedia services such as VoIP, IPTV and video conference, strongly requires guaranteed QoS provisioning with seamless secure mobility during handover among IEEE 802.11 access points. The most important element of handover delay is channel scanning. Most of the existing channel scanning schemes, however, take more than 100 ms and do not guarantee the jitter requirement of less than 50 ms, which is required to guarantee the QoS of real-time services. This paper proposes a smart channel scanning where the channel scanning is carefully scheduled based on predicting the channel scanning time and interleaved frame delivery with limited jitter. This paper also describes an analytical model for predicting smart channel scanning time. The correctness of the prediction of channel scanning delay is analyzed through a series of experiments in a real testbed environment with more than 20 mobile nodes with MadWiFi interface cards. Also, the performance of the proposed smart scanning is compared with that of other schemes via network simulations. It is verified that the proposed smart channel scanning can provide QoSguaranteed handovers with limited jitter of less than 50 ms and no packet losses in various conditions. The proposed smart channel scanning outperforms the existing scanning scheme under various topology configurations in terms of packet loss, jitter, service disruption time and total scanning time. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a noise reduction method and an adaptive contrast enhancement for local tone mapping (TM). The proposed local TM algorithm compresses the luminance of high dynamic range (HDR) image and decomposes the compressed luminance of HDR image into multi-scale subbands using the discrete wavelet transform. For noise reduction, the decomposed images are filtered using a bilateral filter and soft-thresholding. And then, the dynamic ranges of the filtered subbands are enhanced by considering local contrast using the modified luminance compression function. Finally, the color of the tone-mapped image is reproduced using an adaptive saturation control parameter. We generate the tone-mapped image using the proposed local TM. Computer simulation with noisy HDR images shows the effectiveness of the proposed local TM algorithm in terms of visual quality as well as the local contrast. It can be used in various displays with noise reduction and contrast enhancement. [ABSTRACT FROM PUBLISHER]

In this paper, we focus on the design of bit mapping scheme to improve the error-control performance for the second generation digital video broadcasting-terrestrial (DVB-T2) standard. Generally in the case of low-density parity-check (LDPC)-coded modulation system, the nonuniform bit reliabilities inherent to the high-order modulation and irregular LDPC code imply the mismatch between the decoder and the demodulator. Hence, the bit mapping is plugged between the two modules to match the unequal error protections (UEPs) of different coded bits to different modulation levels. This scheme gives a remarkable performance improvement with no added complexity in the bit-interleaved coded modulation (BICM) system. By performing the curve-fitting on the extrinsic information transfer (EXIT) chart, we propose a DEMUX design methodology to improve the bit mapping scheme. Design examples are given for the DVB-T2 system under the AWGN channel as well as the Rayleigh channel. Simulation results indicate that the proposed DEMUX schemes can even surpass the performance of the DEMUX operation specified in the DVB-T2 standard1. [ABSTRACT FROM AUTHOR]

This paper presents a new architecture for the fast computation of the 8x8 two dimensional (2D) Inverse Discrete Cosine Transform (IDCT). The key idea of the proposed method is the permanent storage of the Basis Matrices of the 8x8 2D Discrete Cosine Transform (DCT). By exploiting the sparseness property of the 2D DCT coefficient matrix, the computational time decreases as the number of nonzero coefficients decreases. Moreover, by exploiting the symmetry properties inherent in the Basis Matrices, the introduced method reduces the number of multipliers as well as the number of required multiplications. The proposed structure computes all 64 pixel luminance values of an 8x8 block simultaneously. The efficiency of the proposed architecture is validated through simulations. [ABSTRACT FROM AUTHOR]

This paper presents an integrated deblurring and sharpness enhancement algorithm for restoration of images corrupted by mild blur and improvement of image details. The proposed algorithm is capable of capturing local image structure by adaptively clustering pixels geometric and radiometric features based on their local augmented variational series. By selectively utilizing the segmented features, deblurring and/or sharpening can be effectively performed without either producing noise magnification or over-sharpening artifacts. Experimental results from both simulated and real image data, which are comparable to recently published results, show that the proposed algorithm is superior over the state-of-the-arts. In addition, the proposed method is fully automated with no manual set-up and it enjoys the luxury of fast processing time. These make the proposed algorithm practically useful for image applications in consumer electronic products. [ABSTRACT FROM AUTHOR]

As Internet Protocol Television (IPTV) is becoming increasingly popular, users can enjoy a variety of contents from hundreds of IPTV channels. However, the increased number of channels makes users even more difficult to find their desired contents. Along with this problem, the channel zapping time of IPTV incurs serious user-perceived latency. To alleviate these problems, this paper presents a new channel prefetching scheme that can be implemented on the IPTV set-top box. The scheme basically fetches the contents of adjacent channels before they are actually requested, similar to the adjacency-based prefetching scheme. However, it differentiates the number of channels to be prefetched among up-direction and down-direction channels based on the popularity of channels. Trace-driven simulations with various experimental conditions show that the proposed prefetching scheme performs better than existing prefetching schemes in terms of the prefetching hit rate to find the desired channel. Specifically, when the number of IPTV channels is 150, the average improvement of the hit rate is 22.3% compared to the adjacency-based prefetching scheme. [ABSTRACT FROM AUTHOR]

This paper proposes an improved pilot-based algorithm for joint estimation of carrier frequency offset (CFO) and sampling frequency offset (SFO) in ultrawideband orthogonal frequency division multiplexing (UWBOFDM) systems with cyclic delay diversity. By proper selection of cyclic delay time and a frequency band with maximum channel power, a joint estimation of CFO and SFO is derived. Via computer simulation and analysis, the proposed frequency estimator is shown to benefit from the properly selected delay parameter and frequency band. [ABSTRACT FROM AUTHOR]