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Spectrum sensing is a critical step in cognitive radio to learn the radio environment. Despite its long history, in recent years spectrum sensing has attracted substantial interests from the cognitive radio community as well as other areas. Although there have been many methods, most of them need some idealistic assumptions and are hardly applicable in real cognitive radio practice. In this paper,...
We consider the design of a multi-input multi-output (MIMO) transmission system equipped with distributed, single-antenna amplify-and-forward relays. In particular, we consider how to optimize the complex forwarding coefficients of the relays to maximize the system capacity. Existing studies on MIMO relay network designs mostly concentrate on the case of single relay with multiple antennas, whose...
Location estimation and tracking for the mobile stations have attracted a significant amount of attention in recent years. Moreover, different types of signal sources are considered available to provide the measurement inputs for location estimation and tracking. In this paper, a hybrid unified Kalman tracking (HUKT) technique is proposed to provide an integrated algorithm for precise location tracking...
We propose a novel tracking algorithm called slide window tracker (SWT) suitable for maneuvering target. To efficiently estimate trajectory of moving target, we adopt a sliding piecewise linear window which includes past trace information. By adjusting the window parameters, the proposed algorithm is to reduce measurement noise and to track fast maneuvering target with little computational increment...
Signals of Galileo and modernized GPS will provide a new possibility in the next five years that will enable to overcome current limitations in indoor/urban environments. With modernization of GPS L1C, L2C, L5 and full deployment of Galileo, E1b, c, E5a, b, E6 signals will be available. It is therefore of major interest to assess new capabilities of the incoming GNSS signals and their potential for...
In mobile and portable wireless devices, it is important to have low power dissipation so as to maximize battery life. As the overall power dissipation of a device is dominated by the radio frequency (RF) front end rather than the digital circuit, low-power RF front end design has become a very hot topic in both research and implementation. In this paper, we propose a design method to minimize the...
The first stage of the signal processing chain in a Global Positioning System (GPS) receiver is the acquisition, which provides for a desired satellite coarse code phase and Doppler frequency estimates to subsequent stages. Thus, acquisition is a two-dimensional search, implemented as demodulation and non-coherent correlation. For a certain Doppler estimate, software-defined GPS receivers typically...
This paper addresses multiple access in MIMO wireless networks. It compares two distributed interference alignment techniques, in space and in frequency, that both aim at removing interferences through orthogonalization. The theoretical advantages and drawbacks of each technique are highlighted. Then, the multiplexing gain and the computational complexity are analytically evaluated. It is shown that...
Spectrum sensing is a key component of cognitive radio networks. Compared with the single user spectrum sensing, cooperative spectrum sensing can detect the existence of the primary signal for improving the inference accuracy. However, cooperation induces additional communications overhead. In this paper, we propose a new cooperative spectrum sensing scheme with a light communication overhead caused...
The estimation of the position of an emitting source is an important aspect of emerging cognitive radio systems. We readdress the known problem of estimating the Direction-of-Arrival (DOA) of an emitting source via passive radio means, namely an antenna array. The challenges in the considered scenarios are (a) time-varying, terrestrial multipath propagation with medium-to-low SNR and (b) very short...
In this work, an efficient interleaving process is proposed for orthogonal frequency division multiplexing (OFDM) systems over impulsive noise channels. Unlike the conventional OFDM systems where the interleaving process is implemented before the inverse discrete Fourier transform (IDFT), the proposed scheme is based on performing the interleaving process post the IDFT. The aim of this process is...
3GPP has specified that terminals can be configured to use either 2 or 10 ms transmission time interval in high speed uplink packet access systems. The purpose of this paper is to evaluate the benefit of exploiting a mixture of both of the transmissions time intervals within a cell instead of only one. The study is quantified by means of studying the achievable coverage of voice over IP and possible...
Spectrally Efficient Frequency Division Multiplexing (SEFDM) system proposes enhanced spectrum utilization in contrast to Orthogonal Frequency Division Multiplexing system (OFDM). Spectral efficiency is increased by relaxing the orthogonality condition while maintaining the same transmission rate per individual channel, hence, for the same bandwidth allocation SEFDM offers higher throughput than OFDM...
As cameras become cheaper and gain popularity, vision-based input devices are highly desired and may now become a feasible solution. In this paper, a vision-based virtual piano mechanism is proposed. By tacking and analyzing the motion of the fingertips, the system can detect keystrokes and play the corresponding note on a seven-key virtual piano. Experimental results show the precision and efficiency...
In-Band On-Channe (IBOC) digital audio broadcasting (DAB) is a method of digital audio radio , which could transmit analog FM and digital audio simultaneously. However, due to the existence of fading and interference in FM bands, transmit capacity has reached its limitations for the bandwidth, thus, adding digital transmission in the crowded FM band is a challenging proposition. Diversity is one of...
Recognizing continuous finger spelling plays an important role in understanding sign language. There are two major phases in recognizing continuous finger spelling, which are posture segmentation and posture recognition. In the former, a continuous gesture sequence is decomposed into segments, which are then used for the latter to identify corresponding characters. Among all the segments, beside valid...
Based on a formal characterization of time-series and state-sequences, a new distance measurement dealing with both non-temporal and temporal distances for state-sequence matching is proposed in this paper. In addition to formulating the temporal order over state-sequences, it also takes into account of temporal distances in terms of both the temporal duration of each state and the temporal gaps between...
The gyro stabilized platform control is required to isolate the line of sight (LOS) from the disturbance and vibration of carrier and ensure pointing and tracking for target in electro-optical tracking system. A compound adaptive fuzzy PID control with hysteresis-band switching is developed for this servo system with nonlinear property and some uncertainties. Here, in the adaptive fuzzy controller,...
Iris Recognition has emerged as one of the best biometric authentication techniques in recent years. However, a significant drawback of this biometric modality is the constrained environment in which the user is enrolled and recognized. It typically requires the user to be very cooperative for good quality images to be captured. If this limitation could be effectively addressed, it would be possible...
Adaptive median filtering method was mainly used for filtering Salt&Pepper (impulse) noise, while the method based on Curvelet transform was mainly used for filtering Gaussian noise. In the actual processing for sealed rubber ring image, which usually contains the mixture of Salt&Pepper noise and Gaussian noise. In order to filter out the mixed noisy image preferably, a new mixed filtering...
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