In this paper, an iterative robust minimum-mean square error (MMSE) receiver for space-time block coding (STBC) is proposed to mitigate the performance degradations caused by channel state information (CSI) errors. The proposed scheme estimates an instantaneous covariance matrix of the effective noise, which includes additive white Gaussian noise and the effect of CSI errors. For this estimation, multiple solution candidate vectors are selected based on the distances between the MMSE estimate of the solution and the constellation points, and their a-posteriori probabilities are utilized to execute the estimation of the covariance matrix. To improve the estimation accuracy, the estimated covariance matrix is updated iteratively. Simulation results show that proposed robust receiver achieves substantial performance gains in terms of bit error rates as compared to conventional receiver schemes under CSI errors.

We are concerned with a CDMA cellular system with unbalanced traffic environment such that a cell with high traffic should be assigned a frequency additional to the common one shared with its neighboring cells. To remove quality-dropping inter-cell hard handoffs, the cell with high traffic was first partitioned into three regions. Then, the common frequency is assigned in the outermost region, and the additional frequency is operated in the innermost region, whereas both the common frequency and the additional frequency are operated in the middle region. This frequency assignment strategy is shown not only to remove inter-cell hard handoffs without requiring extra hardware, but also to reduce intra-cell hard handoffs.

In this paper, we propose a joint diversity algorithm for error-rate minimization in multi-user spatial multiplexing (SM) systems with block diagonalization (BD)-precoding. The proposed algorithm adapts or selects the user set, transmit antenna subset, and the number of streams by an exhaustive search over the available resources. The proposed algorithm makes use of the multi-user diversity (MUD) and the spatial diversity gains as well as the array gain through selecting the best set. Exhaustive search, however, imposes a heavy burden in terms of computational complexity which exponentially increases with the size of the total number of users, streams, and transmit antennas. For complexity reduction, we propose two suboptimal algorithms which reduce the search space by first selecting the best user or by both selecting the best user and fixing the number of streams. Simulation results show that the proposed algorithms improve error probability over the conventional algorithm due to their diversity improvement and the signal-to-noise ratio (SNR) gains over the conventional algorithm. We also show that the suboptimal algorithms significantly reduce the computational complexity over exhaustive search with low-SNR loss.

Currently, Mobile IPv6 (MIPv6) working group of Internet Engineering Task Force (IETF) recommends to execute the Binding Update (BU) using Return Routability (RR) procedure. However, the RR procedure doesn't entirely satisfy the security requirements of MIPv6. The previous BU protocols are also likely to reduce the efficiency since they iterate entirely BU protocol courses in Pico/Micro cellular environment in which it occurs frequently handoff or handover and some protocols don't consider that the Correspondent Node (CN) is movable node and has the limited resources. In this paper we propose the ETBU protocol, which is based on Cryptographically Generated Address (CGA) to provide mutual authentication between nodes; it considers that the CN is a movable node. This protocol doesn't require a Mobile Node (MN) to create a signature each time it obtains a new Care-of Address (CoA) unlike the previous CGA-based BU protocol. An MN and its CN issue the ticket to minimize the computing costs that need to calculate CGA. Also, the ETBU protocol minimizes the loss of traffic using smooth handoff or handover. A performance analysis shows that the scheme provides the security as much as the previous BU protocols and more efficiency than them in case that each node obtains the ticket. Therefore, the proposed ETBU protocol can be applied easily to the mobile network environments.

In this paper, for real-time automatic image transform based lip-reading under illumination variations, an efficient (smaller feature data size) and robust (better recognition under different lighting conditions) method is proposed. Image transform based approach obtains a compressed representation of image pixel values of speaker's mouth and is reported to show superior lip-reading performance. However, this approach inevitably produces large feature vectors relevant to lip information to require much computation time for lip-reading even when principal component analysis (PCA) is applied. To reduce the necessary dimension of feature vectors, the proposed method folded the lip image based on its symmetry in a frame image. This method also compensates the unbalanced illumination between the left and the right lip areas. Additionally, to filter out the inter-frame time-domain spectral distortion of each pixel contaminated by illumination noise, our method adapted the hi-pass filtering on the variations of pixel values between consecutive frames. In the experimental results performed on database recorded at various lighting conditions, the proposed lip-folding or/and inter-frame filtering reduced much the necessary number of feature data, principal components in this work, and showed superior recognition rate compared to the conventional method.

3GPP (3rd Generation Partnership Project) has started to discuss D2D (Device-to-Device)-aided OTDOA (Observed Time Difference Of Arrival) as one of the mobile positioning enhancement techniques for LTE (Long Term Evolution) systems. It is a kind of multi-node based OTDOA which directly receives D2D signals from adjacent multiple UEs (User Equipment) to measure RSTD (Reference Signal's Time Difference). D2D signals provide valuable advantages in terms of OTDOA positioning because it can guarantee more reference nodes and high SNR (Signal-to-Noise Ratio) of PRS (Positioning Reference Signal). Two typical methods for multi-node based OTDOA can be applied to D2D-aided OTDOA. Multiple OTDOA positioning is one of the multi-node based methods that averages multiple results from OTDOA; however, it cannot always guarantee high accuracy due to the non-uniform geometry of UEs. OTDOA positioning based on TSE (Taylor Series Expansion) algorithm may be one of the solutions; however, it has the initial value problem and high computational complexity due to its iterative procedure. Therefore, in this paper, we propose a novel D2D-aided OTDOA positioning method which utilizes UEs not as reference node of OTDOA but as assisting node for RSTD error reduction. The proposed method can reduce RSTD error of eNB based hyperbola by using multiple hyperbola bands. The hyperbola band indicates the possible range in which a hyperbola can occur due to RSTD error. Then, by using principal axes of hyperbolas, we estimate a modified hyperbola from the overlap area of hyperbola bands, which has less RSTD error. We verify that the proposed method can effectively reduce RSTD error and improve positioning performance with lower computational complexity.

The superconducting band-pass filter has small insertion loss and excellent out-of-band rejection properties. It has been put to practical use in a number of applications. However, in order to expand its range of application, a tuning technique that can restore the filter characteristics is needed. We propose an automatic tuning system using a trimming library and checked the feasibility of the system by tuning a forward-coupled filter with three resonators. The results show that the trimming library method is an effective way of automatically improving the filter characteristics.

In this paper, we propose a time and memory efficient Ultra Wide Band Short Range Radar (UWB SRR) system for measuring relative target velocities of up to 150km/hr. First, for the proposed detector, we select the required design parameters for good performance. The parameters are the number of coherent integrations, non-coherent integrations, and FFT points. The conventional detector uses a Fast Fourier Transform (FFT) to extract the range and velocity of the target simultaneously. Therefore, it requires high computation effort, high FFT processing time, and a huge amount of memory. However, the proposed pulse radar detector first decides the target range and then computes the target velocity using FFT sequentially for the decided range index. According to our theoretical and simulation analyses, the FFT processing time and the memory requirement are reduced compared to those of the conventional method. Finally, we show that the detection performance of the proposed detector is superior to that of the conventional detector in a background of Additive White Gaussian Noise (AWGN).

In this paper, we propose a corpus-based lip-sync algorithm for natural face animation. For this purpose, we constructed a Korean audio-visual (AV) corpus. Based on this AV corpus, we propose a concatenation method of AV units, which is similar to a corpus-based text-to-speech system. For our AV corpus, lip-related parameters were extracted from every video-recorded facial shot which of speaker reads the given texts selected from newspapers. The spoken utterances were labeled with HTK and such prosodic information as duration, pitch and intensity was extracted as lip-sync parameters. Based on the constructed AV corpus, basic synthetic units are set by CVC-syllable units. For the best concatenation performance, based on the phonetic environment distance and the prosodic distance, the best path is estimated by a general Viterbi search algorithm. From the computer simulation results, we found that the information concerned with not only duration but also pitch and intensity is useful to enhance the lip-sync performance. And the reconstructed lip parameters have almost equal values to those of the original parameters.

In automotive frequency modulated continuous wave (FMCW) radar based on multiple ramps with different slope, an effective pairing algorithm is required to simultaneously detect the target range and velocity. That is, as finding beat-frequencies intersecting at a single point of the range-Doppler map, we extract the range and velocity of a target. Unlike the ideal case, however, in a real radar system, even though multiple beat frequencies are originated from the same target, these beat frequencies have many different intersection values, resulting in mismatch pairing during the pairing step. Moreover, this problem also reduces the detection accuracy and the radar detection performance. In this study, we found that mismatch pairing is caused by the round-off errors of the range-beat frequency and Doppler frequency, as well as their various combinations in the discrete frequency domain. We also investigated the effect of mismatch pairing on detection performance, and proposed a new approach to minimize this problem. First, we propose integer and half-integer frequency position-based pairing method during extraction of the range and Doppler frequencies in each ramp to increase detection accuracy. Second, we propose a window-based pairing method to identify the same target from range-Doppler frequencies extracted in the first step. We also find the appropriate window size to overcome pairing mismatch. Finally, we propose the method to obtain a higher accuracy of range and velocity by weighting the values determined in one window. To verify the detection performance of the proposed method by comparison with the typical method, simulations were conducted. Then, in a real field test using the developed radar prototype, the detection probability of the proposed algorithm showed more than 60% improvement in comparison with the conventional method.

This paper presents the design of a CMOS RF Power Detector (PD) using 0.18 µm standard CMOS technology. The PD is an improved unbalanced source coupled pair incorporating an output differential amplifier and sink current steering. It realizes an input detectable power range of -30 to -20 dBm over 0.1-1 GHz. Also it shows a maximum data rate of 30 Mbps with 2 pF output loading under OOK modulation. The overall current consumption is 1.9 mA under a 1.5 V supply.

In this paper, we study the impact of opportunistic user scheduling on the outage probability of cognitive radio (CR) multiple-input multiple-output (MIMO) systems in the high power region where the peak transmit power constraint is higher than the peak interference constraint. The primary contributions of this paper are the derivation of exact closed-form expressions of the proposed scheduled CR-MIMO systems for outage probability and asymptotic analysis to quantify the diversity order and signal to noise ratio (SNR) gain. Through exact analytical results, we provide the achievable outage probability of the proposed scheduled systems as a function of SNR. Also, through asymptotic analysis, we show that the scheduled CR-MIMO systems provide some diversity order gain over the non-scheduled CR-MIMO systems which comes from multi-user diversity (MUD). Also, the SNR gain of the proposed scheduled systems is identical to that of the non-scheduled CR-MIMO systems.

This paper derived a closed-form expression for inter-flow capacity of a backhaul wireless mesh network (WMN) with centralized scheduling by employing a ring-based approach. Through the definition of an interference area, we are able to accurately describe a bottleneck collision area for a WMN and calculate the upper bound of inter-flow capacity. The closed-form expression shows that the upper bound is a function of the ratio between transmission range and network radius. Simulations and numerical analysis show that our analytic solution can better estimate the inter-flow capacity of WMNs than that of previous approach.

A new structure learning approach for Bayesian networks (BNs) based on dual genetic algorithm (DGA) is proposed in this paper. An individual of the population is represented as a dual chromosome composed of two chromosomes. The first chromosome represents the ordering among the BN nodes and the second represents the conditional dependencies among the ordered BN nodes. It is rigorously shown that there is no BN structure that cannot be encoded by the proposed dual genetic encoding and the proposed encoding explores the entire solution space of the BN structures. In contrast with existing GA-based structure learning methods, the proposed method learns not only the topology of the BN nodes, but also the ordering among the BN nodes, thereby, exploring the wider solution space of a given problem than the existing method. The dual genetic operators are closed in the set of the admissible individuals. The proposed method is applied to real-world and benchmark applications, while its effectiveness is demonstrated through computer simulation.

In this paper, we propose a memory-efficient structure for a pulse Doppler radar in order to reduce the hardware's complexity. The conventional pulse Doppler radar is computed by fast frequency transform (FFT) of all range cells in order to extract the velocity of targets. We observed that this method requires a huge amount of memory to perform the FFT processes for all of the range cells. Therefore, instead of detecting the velocity of all range cells, the proposed architecture extracts the velocity of the targets by using the cells related to the moving targets. According to our simulations and experiments, the detection performance of this proposed architecture is 93.5%, and the proposed structure can reduce the hardware's complexity by up to 66.2% compared with the conventional structure.

In video streaming applications over the Internet, TCP-friendly rate control schemes are useful for improving network stability and inter-protocol fairness. However, they do not always guarantee a smooth video streaming. To simultaneously satisfy both the network and user requirements, video streaming applications should be quality-adaptive. In this paper, we propose a new quality adaptation mechanism to adjust the quality of congestion-controlled video stream by controlling the frame rate. Based on the current network condition, it controls the frame rate of video stream and the sending rate in a TCP-friendly manner. Through a simulation, we prove that our adaptation mechanism appropriately adjusts the quality of video stream while improving network stability.

A dielectric resonator with a gap between the top plate and the rest has been useful for measuring the penetration depth (λ) of superconductor films, a parameter essential for obtaining the intrinsic microwave surface resistance (Rs) of thin superconductor films. We investigated effects of a gap on the microwave properties of TE0ml-mode sapphire resonators with a gap between the top plate and the rest of the resonator. Regardless of a 10 µm-gap in TE0ml-mode sapphire resonators, variations of the TE0ml-mode resonant frequency on temperature (Δf0) as well as TE0ml-mode unloaded Q remained almost the same due to lack of axial currents inside the resonator and negligible radiation effects. The λ of YBa2Cu3O7-δ (YBCO) films obtained from a fit to the temperature-dependent Δf0 appeared to be 195 nm at 0 K and 19.3 GHz, which was well compared with the corresponding value of 193 nm at 10 kHz measured by the mutual inductance method. The intrinsic Rs of YBCO films on the order of 1 mΩ, and the tan δ of sapphire on the order of 10-8 at 15 K and 40 GHz could be measured simultaneously using sapphire resonators with a 10 µm-gap.

This work investigates the effect of channel estimation error on the average secrecy outage capacity of dual selection in the presence of multiple eavesdroppers. The dual selection selects a transmit antenna of Alice and Bob (i.e., user terminal) which provide the best received signal to noise ratio (SNR) using channel state information from every user terminals. Using Gaussian approximation, this paper obtains the tight analytical expression of the dual selection for the average secrecy outage capacity over channel estimation error and multiple eavesdroppers. Using asymptotic analysis, this work quantifies the high SNR power offset and the high SNR slope for the average secrecy outage capacity at high SNR.

Intelligent transportation systems (ITSs) have been extensively studied in recent years to improve the safety and efficiency of transportation. The use of a radar system to enable the ITSs monitor the environment is robust to weather conditions and is less invasive to user privacy. Moreover, equipping the roadside units (RSUs) with radar modules has been deemed an economical and efficient option for ITS operators. However, because the detection and tracking parameters can significantly influence the radar system performance and the best parameters for different scenarios are different, the selection of appropriate parameters for the radar systems is critical. In this study, we investigated radar parameter selection and consequently proposes a parameter selection approach capable of automatically choosing the appropriate detection and tracking parameters for radar systems. The experimental results indicate that the proposed method realizes appropriate selection of parameters, thereby significantly improving the detection and tracking performance of radar systems.

The proposed method tracks the user location in a hierarchically distributed fashion. Call patterns in personal communications services (PCS) have the locality. The virtually hierarchical link (VHL) is used to support the call locality and makes the fast call set up possible. The locality consideration effectively reduces the query traffic compared with non-locality consideration.