Ridha Hamila

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Delay estimation in direct-sequence code-division multiple-access (DS-CDMA) systems is necessary for accurate code synchronization and for applications such as mobile phone positioning. Multipath propagation is among the main sources of error in the DS-CDMA delay estimation process, together with multiple access interference and non-line-of-sight (NLOS)(More)
In this paper, a highly efficient blind band-edge filter-based technique is introduced for the estimation of carrier frequency offsets that are much larger than the subcarrier spacing in orthogonal-frequency-division-multiplexing (OFDM) systems. The proposed scheme is shown to have a high accuracy and an acquisition range that is much larger than the(More)
In this paper, we start by investigating the impact of joint transmit-receive I/Q imbalance on the performance of direct-conversion beamforming OFDM transceivers. We derive a new analytical expression for the average subcarrier SINR of the I/Q imbalance-ignorant beamformer in terms of the I/Q imbalance level at both the transmit and receive sides, the size(More)
The standard Alamouti space-frequency block code (SFBC) suffers from performance degradation when used over highly frequency-selective channels because the channel frequency response is not necessarily flat over the Alamouti block. In this paper, we present an enhanced Alamouti space frequency block decoding scheme for multiple-input multiple-output (MIMO)(More)
In mobile positioning, it is very important to estimate correctly the delay between the transmitter and the receiver. When the receiver is in line-of-sight (LOS) condition with the transmitter, the computation of the mobile position in two dimensions becomes straightforward. In this paper, the problem of LOS detection in WCDMA for mobile positioning is(More)
We present in this paper a novel and efficient technique for the restoration of color images which are highly corrupted with impulse noise. This is a detectionestimation based approach in which outliers are first detected using a Teager-like operator followed by a locally adaptive threshold. Center pixels whose “energy” exceeds some threshold are replaced(More)
In this paper, a channel estimator using neural network is presented for Long Term Evolution (LTE) uplink. This paper considers multiuser SC-FDMA uplink transmissions with doubly selective channels. This channel estimation method uses knowledge of pilot channel properties to estimate the unknown channel response at non-pilot sub-carriers. First, the neural(More)
Phase noise (PHN) and in-phase/quadrature (I/Q) imbalance are two major radio-frequency (RF) impairments in direct-conversion wireless transceivers. Beamforming and orthogonal frequency-division multiplexing (OFDM) schemes have been adopted in broadband wireless standards due to their significant performance gains. In this paper, we analyze the impact of(More)
Privacy and security have an increasingly important role in wireless networks. A secure communication enables a legitimate destination to successfully retrieve information sent by a source, while it disables the eavesdropper (illegitimate destination) to interpret the intercepted information. Physical (PHY) layer security approaches for wireless(More)
Interpolation filters are used to interpolate new sample values at arbitrary time instants between the existing discrete-time samples. Interpolation filters utilizing polynomial-based interpolation can be efficiently implemented using the Farrow structure. This paper introduces a new method for designing Farrow-structured interpolation filters. The proposed(More)