We present in this paper a new visual tracking framework based on the MCMC-based particle algorithm. Firstly, in order to obtain a more informative likelihood, we propose to combine the color-based observation model with a detection confidence density obtained from the Histograms of Oriented Gradients (HOG) descriptor. The MCMC-based particle algorithm is then employed to estimate the posterior distribution of the target state to solve the tracking problem. The global system has been tested on different real datasets. Experimental results demonstrate the robustness of the proposed system in several difficult scenarios.

Decoding a severely blurred 2D barcode can be considered as a special case of blind image restoration issue. In this paper, we propose an appropriate system model which includes the original image with the particularities related to barcode, the blur and the observed image. We develop an unsupervised algorithm that jointly estimates the blur and detects the symbols using the maximum likelihood (ML) criterion. Besides, we show that when taking into account the spatial properties of the barcode, the prohibitive complexity of the ML algorithm can be reduced without degrading its performance. Simulation results show that the algorithm performs accurate estimation of the blur and achieves good performance for symbol detection which is close to that obtained with supervised algorithm.

Future wireless communication systems are intended to offer multimedia services to a large number of subscribers at the same time. The MC-CDMA technique has recently gained considerable attention for many future communication systems due to its ability to support high rates while ameliorating ISI and channel propagation effects. This paper investigates the performance analysis and simulation of a MC-CDMA systems with several spreading codes operating over a doubly selective channel. The time selectivity is modelled by the Doppler spread. The Doppler spread is the difference in Doppler frequencies between different channel paths. The performances are presented in term of bit error rate (BER) as a function of the Doppler frequency for several values of signal to noise ratio (SNR) and for different number of users. Numerical results show that the Carrier Interferometry (CI) codes give the best performance for multi interfering users.

This paper compares the sensitivity to phase noise of different transmission and multiple access techniques : DS-CDMA, OFDM-TDMA, MC-CDMA. The comparison is based on the degradation expressed as the additional Eb/N0 required to achieve a BER of 10(-3) in the presence of phase noise.

With the rising number of modulation types used in multiuser communication systems, we need to find efficient methods to discriminate them. Indeed, modulation recognition has become important in wireless communications for both civilian and military applications. Traditionally, to classify modulation types, most studies assume abundant a priori knowledge about modulated signals such as binary data rate, baud rate or carrier frequency. However, new transmission receiver systems need to classify automatically digital modulations without specific information. In the course of making decision on modulation type, these parameters may have to be estimated in order to perform efficient demodulation. This paper proposes a new way of estimating baud rate of digital modulated signals. This approach is based on abrupt changes detection in time-frequency plane and on abrupt change periodicity analysis using Kalman filtering.

High data rate transmission in an indoor environment is an important issue for the next generation of wireless communications systems. For high data rate links (155 Mbits/s) a large channel around 60 GHz has been allocated world-wide for unlicensed, dense wireless local communications. However this indoor channel is a fading channel and an improved modulation technique is required to obtain such high data rate. In this paper, we propose a comparison of two adaptive modulation techniques based on OFDM. Tests have been realized on simulated channels as well as real indoor channel.

The goal of the paper is to show that a Gaussian approximation can be used to model the global noise in a DS-CDMA system on a 60 GHz frequency band. We show that this approximation can also include the noise due to multipath and to imperfections in power control. The model can then be used as a first step and a reference when designing a communication architecture adapted to this frequency band for mobile indoor cellular systems.

With the rising number of modulation types used in multi-user communication systems, we need to find efficient methods to discriminate them. Indeed, modulation recognition has become important in wireless communications for both civilian and military applications. Traditionally, to classify modulation types, most studies assume abundant a priori knowledge about modulated signals such as binary data rate, baud rate or carrier frequency. However, new transmission/receiver systems need to classify automatically digital modulations without specific information. In the course of making decision on modulation type, these parameters may have to be estimated in order to perform efficient demodulation. We propose a new way of estimating the baud rate of digitally modulated signals and then some perspectives to estimate the binary data rate. This approach is based on abrupt changes detection in the time-frequency plane.

This paper analyzes the suitability of various multiple access schemes for a 60 GHz mobile ad hoc network. The investigated techniques include multi-carrier modulation (OFDM-TDMA), the spectrum spreading method (DS-CDMA) and the combined schemes (MC-CDMA, MC-DS-CDMA) benefiting from the advantages of both techniques. The comparison between these different multiple access schemes is focussed on two aspects: (i) sensitivity to phase noise; the large available bandwidth around 60 GHz is very suitable for transmission of high data rate in indoor environments, but one issue in the 60 GHz band is the design of oscillators with moderate phase noise; (ii) robustness to imperfect power control; ad hoc networks consist of a set of mobile terminals communicating among themselves without any central controller; radio resource management has to be conducted in a distributed way and the power control is inherently imperfect.

We present a multipath channel impulse response model for 60 GHz indoor wireless systems. During the propagation, the electromagnetic wave is reflected on various objects present in the environment. On each object, the impacts of the reflections contributing to the received signal form clusters whose size depends on the nature of the object and on its orientation. By considering the physical mechanism responsible for indoor propagation and also the methodology of measurement, we show that our statistical channel impulse response model fits our measurements well, that the Rayleigh model is a special case, and that our model can be extended to any kind of room

Transmission of high rate data in an indoor environment is an important issue for personal or industrial applications. Millimetric waves are one possibility for such transmissions. Because they are strongly attenuated they are very interesting to simplify the frequency planning and to reduce the electro-magnetic pollution. They also offer a large available bandwidth to allow high rate transmissions. However, the first encountered problem to build systems at this frequency is the absence of accurate data about the channel and the consequences of fading or interference between symbols for high data rate links (155 Mbits/s). We propose a contribution to the indoor 60 GHz channel characterization. We also try to define a stationary model in order to use it in simulations. The model is based on a statistical study of the measured data

Significant investigation has been conducted towards combining OFDM which mitigates intersymbol interference and SDMA which improves the bandwidth efficiency. OFDM-SDMA systems need accurate channel estimation, because it is from this information that the separation of co-channel users is performed. Usually, the channel is assumed stationary because the frame duration is chosen smaller than the coherence time. However this choice limits the system efficiency. This paper discusses the performance of an OFDM-SDMA based system under a time-varying multi-path channel. The system under study uses the basic combining algorithm based on the linear minimum mean square error (MMSE) criterion for user separation and a pilot based scheme independent from channel statistics for channel estimation. We investigate in particular the effect of the pilot subcarrier arrangement on the BER performance and deduce an optimal configuration in a channel with both delay and Doppler spread