Maximally flat digital differentiators (MFDDs) are widely used in many applications. By using MFDDs, we obtain the derivative of an input signal with high accuracy around their center frequency of flat property. Moreover, to avoid the influence of noise, it is desirable to attenuate the magnitude property of MFDDs expect for the vicinity of the center frequency. In this paper, we introduce a design method of linear phase FIR band-pass MFDDs with an arbitrary center frequency. The proposed transfer function for both of TYPE III and TYPE IV can be achieved as a closed form function using Jacobi polynomial. Furthermore, we can easily derive the weighting coefficients of the proposed MFDDs using recursive formula. Through some design examples, we confirm that the proposed method can adjust the center frequency arbitrarily and the band width having flat property.

In this paper, the spatial smoothing (SS) method is extended to the wideband multipath case. By reordering the array input signal and the weight vector, the corresponding covariance matrix of each subarray can be constructed conveniently. Then, a novel wideband beamforming algorithm, based on the SS method (SS-WB), can be achieved by linearly constrained minimum variance (LCMV). Further improvement of the output signal-to-interference-plus-noise ratio (SINR) for SS-WB can be obtained by removing the desired signal in the observed array data with the reconstruction of covariance matrix, which is denoted as wideband beamformer based on modified SS method (MSS-WB). Both proposed algorithms can reduce the desired signal cancellation due to the super decorrelation ability of SS method and MSS-WB can lead to a significantly improved output SINR. The simulations verify their effectiveness in the multipath environment.

Bandwidth aggregation (BAG) techniques have been researched for many years in an efforts to enhance throughput for multi-homed streaming service. However, despite of the considerable attention being devoted towards energy-efficient communications, the power efficiency for BAG has not been considered yet. To improve the power efficiency in multi-homed streaming service, this paper proposes Power Minimized Rate Allocation Scheme (PMRAS) with optimal rate allocation at each interface while guaranteeing an allowable packet loss rate. In developing PMRAS, we first formulate a power consumption model based on the network interface state (i.e. active and idle state). We adopt a Lagrangian algorithm to solve the convex optimization problem of power consumption. The performance results gained from a numerical analysis and simulations (NS-2) reveal that the proposed scheme offers superior performance over the existing rate allocation scheme for BAG with guaranteed required quality of service.

Vector processors have significant advantages for next generation multimedia applications (MMAs). One of the advantages is that vector processors can achieve high data transfer performance by using a high bandwidth memory sub-system, resulting in a high sustained computing performance. However, the high bandwidth memory sub-system usually leads to enormous costs in terms of chip area, power and energy consumption. These costs are too expensive for commodity computer systems, which are the main execution platform of MMAs. This paper proposes a new multi-banked cache memory for commodity computer systems called MVP-cache in order to expand the potential of vector architectures on MMAs. Unlike conventional multi-banked cache memories, which employ one tag array and one data array in a sub-cache, MVP-cache associates one tag array with multiple independent data arrays of small-sized cache lines. In this way, MVP-cache realizes less static power consumption on its tag arrays. MVP-cache can also achieve high efficiency on short vector data transfers because the flexibility of data transfers can be improved by independently controlling the data transfers of each data array.

In this paper, the H2/H∞ control problem for a class of stochastic discrete-time linear systems with state-, control-, and external-disturbance-dependent noise or (x, u, v)-dependent noise involving multiple decision makers is investigated. It is shown that the conditions for the existence of a strategy are given by the solvability of cross-coupled stochastic algebraic Riccati equations (CSAREs). Some algorithms for solving these equations are discussed. Moreover, weakly-coupled large-scale stochastic systems are considered as an important application, and some illustrative examples are provided to demonstrate the effectiveness of the proposed decision strategies.

A path loss model for low antenna heights below surrounding buildings in residential areas is presented to contribute to the construction of VHF band wireless systems. The model is constructed on the basis of measurement results at 167.65MHz, near center frequency at VHF band. Path loss characteristics in the middle VHF band are compared to those in bands above UHF. The dominant paths in bands above UHF include propagation paths below surrounding buildings, such as paths along roads. However, in the middle VHF band, these paths are instantly attenuated because their 1st Fresnel zone radius is larger than the average building height or road width. The dominant path in the middle VHF band is the over-roof propagation path, and the 1st Fresnel zone of the path is shielded by the buildings and the ground surface. The proposed path loss model has two features. First, it derives the effective height of the ground surface from the terrain profile of the buildings and the ground surface. Second, it uses formulas of a two-path model to take the shielding of the 1st Fresnel zone into account. Finally, it is shown that the proposed model is able to predict the path loss measurement results more accurately than the conventional model.

The recent development of communication devices and wireless network technologies continues to advance the new era of the Internet and telecommunications. The various “things”, which include not only communication devices but also every other physical object on the planet, are also going to be connected to the Internet, and controlled through wireless networks. This concept, which is referred to as the “Internet of Things (IoT)”, has attracted much attention from many researchers in recent years. The concept of IoT can be associated with multiple research areas such as body area networks, Device-to-Device (D2D) communications networks, home area networks, Unmanned Aerial Vehicle (UAV) networks, satellite networks, and so forth. Also, there are various kinds of applications created by using IoT technologies. Thus, the concept of the IoT is expected to be integrated into our society and support our daily life in the near future. In this paper, we introduce different classifications of IoT with examples of utilizing IoT technologies. In addition, as an example of a practical system using IoT, a tsunami detection system (which is composed of a satellite, sensor terminals, and an active monitoring system for real-time simultaneous utilization of the devices) is introduced. Furthermore, the requirements of the next generation systems with the IoT are delineated in the paper.

Understanding the structure and evolution of spatial-temporal networks is crucial for different fields ranging from urbanism to epidemiology. As location based technologies are pervasively used in our daily life, large amount of sensing data has brought the opportunities to study human activities and city dynamics. Ubiquitous cell phones can be such a sensor to analyze the social connection and boundaries of geographical regions. In this paper, we exploit user mobility based on large-scale mobile phone records to study urban areas. We collect the call data records from 1 million anonymous subscribers of 8 weeks and study the user mobility flux between different regions. First we construct the urban areas as a spatial network and use modularity detection algorithm to study the intrinsic connection between map areas. Second, another generative model which is widely used in linguistic context is adopted to explore the functions of regions. Based on mobile call records we are able to derive the partitions which match boundaries of the administrative districts. Our results can also catch the dynamics of urban area as the basis for city planning and policy making.

Two types of 3D folded dipole antenna with feed line (FDAFL) were reported for a small terminal, which covered WiMAX 2.5/3.5GHz bands and WLAN 2.4GHz band. In this study, folded monopole antenna (FMA) is proposed as a variant of FDAFL. We show the broadband characteristics of FMA and determine the most suitable configuration of FMA array for realizing MIMO system. Also, a multiband variant is created by introducing a parasitic element to FMA. The result is a multiband FMA array with parasitic elements operating at 5GHz band of WiMAX and WLAN as well as WiMAX 2.5/3.5GHz bands and WLAN 2.4GHz band with total antenna efficiency of between 70% to 96% and the envelope correlation coefficient of less than 0.02. Finally, a prototype antenna is implemented, and we confirm the validity of the simulation by comparison to measured results.

Realization of a planar dual-band fork three-way power divider (PDBF3PD) with Cheng's equivalent structure is discussed. The Cheng's structure consists of two open-circuited stubs and a transmission line, and the characteristic impedances tend to be high. As a result, the realizable range of frequency ratios of upper frequency to lower frequency is limited in a narrow area. In this paper, an impedance scale factor is proposed to transform characteristic impedances into a realizable range and to facilitate the design of PDBF3PDs. Theoretical considerations are verified using a simulator of ADS2008U and by an experiment.

In this paper, we consider a parallel ring-line rat-race circuit realized by replacing some parts of the ring-lines with composite right-/left-handed transmission lines (CRLH-TLs). For a conventional rat-race circuit, the minimum coupling factor is limited by the highest impedance of the ring-lines that can be manufactured by general printed circuit board (PCB) technologies. However, the coupling factor of the parallel ring-line type rat-race circuit proposed in this paper is determined by the difference between the admittances of the parallel ring-lines. As a result of designing parallel ring-line rat-race circuits having coupling factors of $-20$ and $-30$,dB for an operation frequency of 4,GHz, the proposed rat-race circuit realizes broadband characteristics of about 35.5% according to the numerical results for the $-20$,dB circuit. Furthermore, broadband characteristics including reflection, isolation, and couplings can be maintained for the fabricated $-20$,dB rat-race circuit up to an input power of 40,dBm.

This paper proposes a sector base station antenna for mobile wireless communication systems employing multiple woodpile metamaterial reflectors and a multiband radiator that establishes the same beamwidth in the horizontal plane for more than two frequency bands. Electromagnetic Band Gap (EBG) characteristics of each metamaterial reflector can be controlled through structural parameters of the woodpile reflector, e.g., the rod width and rod spacing. As an example of the proposed antenna, a design for a triple-frequency-band antenna that radiates at 800 MHz, 2,GHz, and 4,GHz is shown. The algorithm used to adjust the beamwidth of the proposed antenna is newly introduced and adjusts the beamwidth to be the same for each band using the rod width of the woodpile. A prototype of the proposed antenna has the approximately 90$^{circ}$ beamwidth in the horizontal plane at the three frequencies, and the measurement results agree well with the electromagnetic field simulation results.

This paper proposes a new small multiband printed antenna for wireless telecommunications modules that can realize Machine-to-Machine applications. We reconfigure our previous antenna to cover the 700MHz, 800MHz, and 900MHz bands, and add two new elements (second strips) to cover the 2GHz band. The new antenna achieves operation in quad-bands: 700MHz, 800MHz, 900MHz, and 2GHz. Frequency characteristics are analyzed using electromagnetic-simulation software based on the method of moments, and the validity of the numerical results is shown based on measured Voltage Standing Wave Ratio (VSWR) characteristics and the radiation patterns of a prototype antenna. The proposed antenna is compact with a VSWR bandwidth (≤2) of 27.5% in bands including 700MHz, 800MHz, and 900MHz, and a VSWR bandwidth (≤2) of 10.6% in the band including 2GHz. We clarify that the operating mechanism in the 2GHz band is equivalent to that of a one wavelength folded offset fed dipole antenna comprising a monopole element and second strips, and that the operating frequency in the 2GHz band can be determined by the path length from the tip of the monopole element to the tip of the second strip via a feeding point.

This paper describes the design method of a broadband CMOS stacked power amplifier using harmonic control over wide bandwidths in a 0.11,$mu $m standard CMOS process. The high-efficiency can be obtained over wide bandwidths by designing a load impedance circuit as purely reactive as possible to the harmonics with broadband fundamental matching, which is based on continuous Class-F mode of operation. Furthermore, the stacked topology overcomes the low breakdown voltage limit of CMOS transistor and increases output impedance. With a 5-V supply and a fixed matching circuitry, the suggested power amplifier (PA) achieves a saturated output power of over 26.7,dBm and a drain efficiency of over 38% from 1.6,GHz to 2.2,GHz. In W-CDMA modulation signal measurements, the PA generates linear power and power added efficiency of over 23.5,dBm and 33% (@ACLR $=-33$,dBc).

This paper proposes a compact three-mode H-shaped resonator bandpass filter fed by antiparallel coupled input/output lines. To investigate the resonant behavior of the H-shaped resonator, even/odd-mode resonance conditions of the resonator are first derived analytically. The multimode resonances of the H-shaped resonator filter are modeled by a multipath circuit formed with resonance paths. Moreover, a direct source/load coupling path is connected in parallel, of which the value shows a frequency dependency because of the antiparallel coupled feeding lines, thereby generating four transmission zeros (TZs) greater than the number of a theoretical limitation. The H-shaped resonator bandpass filter is synthesized, developed, and tested, showing a third-order passband response with four TZs located near the passband, and a wide stopband property.

Much attention has recently been paid to direction of arrival (DOA) estimation using compressed sensing (CS) techniques, which are sparse signal reconstruction methods. In our previous study, we developed a method for estimating the DOAs of multi-band signals that uses CS processing and that is based on the assumption that incident signals have the same complex amplitudes in all the bands. That method has a higher probability of correct estimation than a single-band DOA estimation method using CS. In this paper, we propose novel DOA estimation methods for multi-band signals with frequency characteristics using the Khatri-Rao product. First, we formulate a method that can estimate DOAs of multi-band signals whose phases alone have frequency dependence. Second, we extend the scheme in such a way that we can estimate DOAs of multi-band signals whose amplitudes and phases both depend on frequency. Finally, we evaluate the performance of the proposed methods through computer simulations and reveal the improvement in estimation performance.

In this paper, compact reconfigurable wideband Inverted-F Antenna (IFA) elements are proposed for a Long Term Evolution (LTE) mobile terminal. The proposed inverted-F antenna has a very simple planar arrangement. A capacitive coupling feed strip is employed to modify the input impedance matching. A chip inductor is connected in series to the feeding point to realize the wideband property. The whole Multiple-Input Multiple-Output (MIMO) antenna system consists of two similar inverted-F antenna elements. Antenna element #1 has a wideband property with a 6-dB bandwidth from 0.74 to 0.9GHz. To further expand the bandwidth, antenna element #2 has a reconfigurable property through the use of a Positive Intrinsic-Negative (PIN) diode. Antenna element #2 has a 6-dB bandwidth from 0.74 to 0.84GHz when the PIN diode is on and from 0.79 to 0.9GHz when the PIN diode is off. Moreover, the proposed MIMO antenna has a low radiation-pattern-based envelope correlation coefficient (ECC), which is less than 0.15 over LTE bands 4, 5, 13, and 14.

This letter proposes a wideband compact DC block design technique. This DC block has a wide pass-band and wide stop-band and transforms termination impedances. It comprises a pair of coupled lines on a defected ground structure (DGS) with capacitor loading. A periodic DGS pattern increases coupling, and, consequently, a wideband DC block design is allowed with a microstrip process on a high dielectric low height substrate. A DC block with equal termination impedances of 50,$Omega$ and another that transforms 50 into 30,$Omega$ are fabricated. The measured fractional bandwidths are 48% and 47%. The size of the DC block is 16.8$ imes$ 15,mm$^2(0.057lambda_0 imes 0.051lambda_0)$.

Decimation and interpolation methods are utilized in image coding for low bit rate image coding. However, the decimation filter (prefilter) and the interpolation filter (postfilter) are irreversible with each other since the prefilter is a wide matrix (a matrix whose number of columns are larger than that of rows) and the postfilter is a tall one (a matrix whose number of rows are larger than that of columns). There will be some distortions in the reconstructed image even without any compression. The method of interpolation-dependent image downsampling (IDID) was used to tackle the problem of producing optimized downsampling images, which led to the optimized prefilter of a given postfilter. We propose integrating the IDID with time-domain lapped transforms (TDLTs) to improve image coding performance.

High-speed wireless access technologies have evolved over the last years setting new challenges for TCP. That is, to effectively utilize the available network resources and to minimize the effects of wireless channel errors on TCP performance. This paper introduces a new TCP variant, called TCP-BIAD aiming at enhancing TCP performance in broadband wireless access networks. We provide analytical expressions for evaluating the stability, throughput, fairness and friendliness properties of our proposal, and we validate our results by means of computer simulations. Initial results presented in this paper show that this approach achieves high network utilization levels in a wide range of network conditions, while maintaining an adequately fair and friendly behavior with respect to coexisting TCP flows.