For a prime p with p≡3 (mod 4) and an odd number m, the Bentness of the p-ary binomial function fa,b(x)=Tr1n(axpm-1)+Tr12 is characterized, where n=2m, a ∈ F*pn, and b ∈ F*p2. The necessary and sufficient conditions of fa,b(x) being Bent are established respectively by an exponential sum and two sequences related to a and b. For the special case of p=3, we further characterize the Bentness of the ternary function fa,b(x) by the Hamming weight of a sequence.

We propose an innovative and practically attainable downlink multi-cell MIMO system with distributed transmit beamforming design. The proposed system is referred to as the MIMO-MAP system which is aimed to mitigate the rank deficiency problem of those MIMO wireless channels that can not support high-order multiplexing gains. In the MIMO-MAP system, each mobile station is allowed to receive several independent data streams from multiple access points at the same time and the same frequency. To do this, a set of noise-subspace-based receive beamformers are employed to suppress the interference among the data streams from different access points. On the other hand, if we consider each receive beamformer as part of its associated wireless channel, we virtually reduce the antenna array at each receive mobile station to a single antenna. With this arrangement, we may have the transmit signal dimension high enough to pre-cancel the inter-stream-interferences at each transmit access point. As a result, the MIMO-MAP channel can be decomposed into a large number of independent subchannels which significantly increase the channel capacity.

Different encoding modes for variable block size are available in the H.264/AVC standard in order to offer better coding quality. However, this also introduces huge computation time due to the exhaustive check for all modes. In this paper, a fast spatial DIRECT mode decision method for profiles supporting B frame encoding (main profile, high profile, etc.) in H.264/AVC is proposed. Statistical analysis on multiple video sequences is carried out, and the strong relationship of mode selection and rate-distortion (RD) cost between the current DIRECT macroblock (MB) and the co-located MBs is observed. With the check of mode condition, predicted RD cost threshold and dynamic parameter update model, the complex mode decision process can be terminated at an early stage even for small QP cases. Simulation results demonstrate the proposed method can achieve much better performance than the original exhaustive rate-distortion optimization (RDO) based mode decision algorithm by reducing up to 56.8% of encoding time for IBPBP picture group and up to 67.8% of encoding time for IBBPBBP picture group while incurring only negligible bit increment and quality degradation.

This paper presents a grid-based, real-time surface modeling algorithm in which the generation of a precise 3D model is possible by considering the user's intention during the course of the spatial input. In order to create the corresponding model according to the user's input data, plausible candidates of wand traversal patterns of grid edges are defined by considering the sequential and directional characteristics of the wand input. The continuity of the connected polygonal surfaces, including the octree space partitioning, is guaranteed without the extra crack-patching algorithm and the pre-defined patterns. Furthermore, the proposed system was shown to be a suitable and effective surface generation tool for the spatial sketching system. It is not possible to implement the unusual input intention of the 3D spatial sketching system using the conventional Marching Cubes algorithm.

Boosting over weak classifiers is widely used in pedestrian detection. As the number of weak classifiers is large, researchers always use a sampling method over weak classifiers before training. The sampling makes the boosting process harder to reach the fixed target. In this paper, we propose a partial derivative guidance for weak classifier mining method which can be used in conjunction with a boosting algorithm. Using weak classifier mining method makes the sampling less degraded in the performance. It has the same effect as testing more weak classifiers while using acceptable time. Experiments demonstrate that our algorithm can process quicker than [1] algorithm in both training and testing, without any performance decrease. The proposed algorithms is easily extending to any other boosting algorithms using a window-scanning style and HOG-like features.

A dual-band divide-by-2 quadrature injection-locked frequency divider (QILFD) is proposed to achieve high-speed, low power, wide-locking range, and accurate quadrature output phases. The QILFD consists of two dual-resonance differential voltage controlled oscillators and four coupling NMOS injectors in a ring configuration. The injectors are used as coupling devices of two differential ILFDs and are also used as common source amplifiers. The proposed QILFD has been implemented with the TSMC 90 nm CMOS technology and the core power consumption is 2.31 mW at the dc drain-source bias of 0.5 V. At the input power of 0 dBm, the low-band and high-band divide-by-2 operation ranges are respectively from 7.0 GHz to 10.1 GHz and 19.8 GHz to 24.6 GHz.

In this letter, a novel adaptive total variation (ATV) model is proposed for image inpainting. The classical TV model is a partial differential equation (PDE)-based technique. While the TV model can preserve the image edges well, it has some drawbacks, such as staircase effect in the inpainted image and slow convergence rate. By analyzing the diffusion mechanism of TV model and introducing a new edge detection operator named difference curvature, we propose a novel ATV inpainting model. The proposed ATV model can diffuse the image information smoothly and quickly, namely, this model not only eliminates the staircase effect but also accelerates the convergence rate. Experimental results demonstrate the effectiveness of the proposed scheme.

We address the stability property of the FAST TCP congestion control algorithm. Based on a continuous-time dynamic model of the FAST TCP network, we establish that FAST TCP in itself is globally exponentially stable without any specific conditions on the congestion control parameter or the update gain. Simulation results demonstrate the validity of the global exponential stability of FAST TCP.

In this paper, a novel receiver architecture is proposed for multiple-input-multiple-output (MIMO) systems; the proposed architecture helps achieve superior performance in multipath fading channels when the number of layered streams exceeds the number of receiving antennas. In this architecture, the concept of “virtual channel” is adopted to attain diversity gain even when successive detection is applied for reducing computational complexity, while orthogonal frequency division multiplexing (OFDM) is employed to combat multipath fading. Actually, successive detection is carried out in all possible virtual channels, and the virtual channel with the minimum error probability is detected with the assistance of the maximum a-posteriori (MAP) decoder in the architecture. In addition, soft input and soft output (SISO) iterative detection is introduced in the virtual channel estimation scheme. The performance of the proposed architecture is verified by computer simulations. This architecture can be implemented with lesser complexity than that in maximum likelihood detection (MLD), but the gain in the former case exceeds that in the latter by 4.5 dB at the BER of 10-3 for 42 MIMO-OFDM.

This paper addresses the problem of sensor selection in wireless sensor networks (WSN) subject to a distortion constraint. To do so, first, a cost function is derived based on the spatial correlation obtained using the best estimation of the event source. Then, a new adaptive algorithm is proposed in which the number of active sensors is adaptively determined and the best topology of the active set is selected based on the add-one-sensor-node-at-a-time method. Simulations results show that the active sensors selected using the proposed cost function have less event distortion. Also, it is shown that the proposed sensor selection algorithm is near optimum and it has better performance than other algorithms with regard to the computational burden and distortion.

Although a large number of query processing algorithms in spatial network database (SNDB) have been studied, there exists little research on route-based queries. Since moving objects move only in spatial networks, route-based queries, like in-route nearest neighbor (IRNN), are essential for Location-based Service (LBS) and Telematics applications. However, the existing IRNN query processing algorithm has a problem in that it does not consider time and space constraints. Therefore, we, in this paper, propose IRNN query processing algorithms which take both time and space constraints into consideration. Finally, we show the effectiveness of our IRNN query processing algorithms considering time and space constraints by comparing them with the existing IRNN algorithm.

In this letter, we propose a Partially Observable Markov Decision Process (POMDP) based Distributed Adaptive Opportunistic Spectrum Access (DA-OSA) Strategy for Cognitive Ad Hoc Networks (CAHNs). In each slot, the source and destination choose a set of channels to sense and then decide the transmission channels based on the sensing results. In order to maximize the throughput for each link, we use the theories of sequential decision and optimal stopping to determine the optimal sensing channel set. Moreover, we also establish the myopic policy and exploit the monotonicity of the reward function that we use, which can be used to reduce the complexity of the sequential decision.

A differential BPSK transmitter for ultra-wideband impulse-radio communication has been presented in this paper. The transmitter, developed in a 65 nm CMOS process,is simple in design and occupies a core area of 0.0017 mm2. The differential Gaussian monocycle pulses (GMP) are generated using some logic blocks and delay elements. The generated GMP, having a center frequency above 5 GHz, meets the FCC regulations. Measured results show that the transmitter consumes 1.8 pJ/bit to transmit BPSK modulated GMP at a data rate of 2 Gb/s. The interface circuitries eliminate the need for external networks for chip to antenna matching. Using an off-chip differential bow-tie antenna, data can easily be transmitted up to a distance of 10 cm which made it suitable for low power far field non-coherent applications.

In this paper, a differential input/output linear MOS transconductor using an adaptively biasing technique is proposed. The proposed transconductor based on a differential pair is linearized by employing an adaptively biasing circuit. The linear characteristic of the individual differential output currents are obtained by introducing the adaptively biased currents to terminate the differential output terminals. Using the proposed technique, the common-mode rejection ration (CMRR) becomes high. Simulation results show that the proposed technique is effective for improvement of the linearity and other performances.

The IP Multimedia Subsystem (IMS) establishes a session between end terminals as a client/server application in the Next Generation Network (NGN). These days, many application services are being provided as Web services. In this letter, we propose a new NGN architecture conforming to the architectural styles of Representational State Transfer (REST), which is a Web service technology for solving interoperability and traffic concentration problems in the Session Initiation Protocol (SIP).

Different from distributed baluns, active baluns have group delay variations in the lower bands related to inherent internal capacitances and resistance in transistors. A negative group delay (NGD) circuit is employed as a compensator of group delay variation for an ultra-wideband (UWB) active balun. First, three-cell NGD circuit is inserted into a simple active balun circuit for realizing both group delay compensation and return loss improvement. The simulated results show a group delay variation of 4.8 ps and an input return loss of above 11.5 dB in the UWB band (3.1-10.6 GHz). Then, a pair of one-cell NGD circuits is added to reduce the remaining group delay variation (3.4 ps in simulation). The circuit with the NGD circuits was fabricated on an InGaP/GaAs HBT MMIC substrate. The measured results achieved a group delay variation of 7.7 ps, a gain variation of 0.5 dB, an input return loss of greater than 10 dB, and an output return loss of larger than 8.1 dB in the UWB band.

In this paper, a 24 GHz frequency source for low phase noise is presented in a 0.18 µm CMOS process. The 24 GHz frequency source chip is composed of a 12 GHz voltage controlled oscillator (VCO) and a 24 GHz balanced frequency doubler with class B gate bias. Compared to a conventional complementary VCO, the proposed 12 GHz VCO has phase noise improvement by using resistor current sources and substituting the nMOS cross-coupled pair in the conventional complementary VCO for a gm-boosted nMOS differential Colpitts pair. The measured phase noise and fundamental frequency suppression are -107.17 dBc/Hz at a 1 MHz offset frequency and -20.95 dB at 23.19 GHz frequency, respectively. The measured frequency tuning range is from 23.19 GHz to 24.76 GHz drawing 2.72 mA at a supply voltage of 1.8 V not including an output buffer.

This paper discusses the possibility of deploying a short-range cognitive radio (secondary communication system) within the service area of a primary system. Although the secondary system interferes with the primary system, there are certain locations in the service area of the primary system where the cognitive radio can reuse the frequency of the primary system without causing harmful interference to it and being disturbed by the primary system. These locations are referred to as having a spatial opportunity for communications in the secondary system, since it can reuse the frequency of the primary system. Simulation results indicate that the antenna gain, beamwidth, and propagation path loss greatly affect the spatial opportunity of frequency reuse for the secondary users. The results show that spatial spectrum reuse can be significantly increased when the primary system users are equipped with directional antennas. An important component in this study is the heterogeneous path loss model, i.e., the path loss model within the primary system is different from the model used to calculate the interference between the primary and the secondary systems. Our results show that the propagation models corresponding to the actual antenna heights in the primary/secondary system can largely impact the possibilities for spectrum reuse by the cognitive radios.

We propose a new majority voting scheme for identifying downlink primary scrambling code, where two voting processes with different coherent correlation intervals (CCIs) are simultaneously performed. A false alarm probability and a threshold adjustment for the proposed scheme are investigated, and it is shown by computer simulations that the proposed scheme can perform well over a wide range of frequency offsets.

Duobinary signaling has been introduced into asymmetric multi-chip communications such as DRAM or display interfaces, which allows a controlled amount of ISI to reduce signaling bandwidth by 2/3. A × 2 oversampled equalization has been developed to realize Duobinary signaling. Symbol-rate clock recovery form Duobinary signal has been developed to reduce power consumption for receivers. A Duobinary transmitter test chip was fabricated with 90-nm CMOS process. A 3.5 dB increase in eye height and a 1.5 times increase in eye width was observed.