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The following topics were dealt with: speech processing; spoken language processing; image processing; multidimensional signal processing; signal processing education; bio imaging; bio signal processing; industry technology track; communication; sensor array; multichannel signal processing; audio; electroacoustics; and machine learning
In a Gaussian MIMO broadcast channel, serving more than one user at a time is generally more beneficial in terms of average sum-rate. Under partial channel state information (CSI) feedback constraints, however, serving only one user at a time can be a better multiple access method when the number of active users in the system is smaller than a certain threshold. This paper uses single user beam-forming...
Iterative multi-user detection and time-variant channel estimation in a multi-carrier (MC) code division multiple access (CDMA) uplink requires high computational complexity. This is mainly due to the linear minimum mean square error (LMMSE) filters that are used for multi-user detection and time-variant channel estimation. Krylov subspace methods allow for an efficient implementation of the LMMSE...
Multiple access schemes in which the transmitting nodes are allowed to cooperate have the potential to provide higher quality of service than conventional schemes. In the class of pairwise cooperative multiple access schemes in which channel state information is available at the transmitters, the allocation of transmission power plays a key role in the realization of these quality of service gains...
We study the problem of designing distributed space-time codes for cooperative communication. A major challenge in distributed cooperative transmissions is to find a way to coordinate the relay transmissions without requiring extra control information overhead. Most of the previous works on the subject assume each node emulates a predetermined antenna of a multiple-antenna system. However, this requires...
We present a simple but general model for feature-based information processing with selective attention. We model feature extraction as projections onto frames of subspaces, which accounts for redundancies in the representations of individual features as well as between features. To manage limited resources, we use feedback attentional signals to dynamically allocate system resources according to...
Cooperative transmission follows the idea to achieve better reception quality for wireless communication systems by exploiting spatial diversity. We discuss the case where a group of sensor nodes transmit cooperatively and simultaneously identical symbols to a far destination. Doing so, they achieve a higher total transmit power. This is useful to reach destinations when no intermediate relays are...
We propose an efficient algorithm that computes the maximum achievable rate of a decode-and-forward multi-relay cooperative system with orthogonal transmissions under total power constraint. In P.A. Angel et al. we have argued that in a system with Q relays the optimum rate can be found by solving Q convex problem despite the fact that the optimization problem is not convex and it belongs to a class...
Transmit-reference ultra-wideband (TR-UWB) systems are attractive due to their relatively low complexity at both the transmitter and the receiver. Partly, this is achieved by making restrictive assumptions such as a frame length which should be much larger than the channel length. This limits their use to low data rate applications. In this paper, we lift this restriction and allow inter-frame interference...
Channel estimation for OFDM systems in rapidly time-varying environments is challenging. In this paper, relying on a basis expansion channel model, we propose a scheme for estimating channel parameters varying within a transmission block. Along with the estimation scheme, we also derive the optimal pilot sequence and optimal placement of pilot tones with respect to the mean square error (MSE) of the...
This paper proposes a subspace-based blind channel estimation method for space-time coded OFDM system. Using only the redundancy induced by OFDM modulation and space-time block coding (STBC), channel state information (CSI) can be blindly estimated, up to two scalar ambiguities for Alamouti STBC or one for 4T4A3K STBC, even when a single receiving antenna is equipped. Compared with other blind channel...
This paper deals with iterative maximum-likelihood synchronization of a scalar parameter. An efficient implementation of the Newton-Raphson (NR) maximum-search method is proposed. Considering the latter implementation, the NR approach is shown to be an attractive alternative to synchronization methods based on the expectation-maximization (EM) algorithm. Simulation results for the case of phase-offset...
In this work we propose a new adaptive channel shortening technique for doubly selective (time-varying frequency-selective) orthogonal frequency division multiplexing (OFDM) channels. OFDM is considered to be a very bandwidth efficient wireless transmission technique (due to its tightly packed orthogonal subcarrier structure) for multi-path channels. Transmissions in multi-path channels exhibiting...
The mathematical models of populations of mutually coupled oscillators having self-synchronization capabilities are a powerful tool for designing sensor networks with high energy efficiency, fault tolerance and scalability. In this work, we derive the conditions for the existence the asymptotic stability of the equilibrium of a system capable to provide maximum likelihood estimates through only local...
The performance of a uniform-threshold scalar quantizer in Wyner-Ziv coding is investigated in this paper. To derive analytical expressions we assume the abstract correlation channel from the side information to the source to be encoded is memoryless, additive Laplacian. Furthermore, in order to focus our attention on the performance of the quantizer, the Wyner-Ziv coding scheme is assumed to encode...
We consider in this paper the analysis of transmit beamforming methods in multiple antenna systems with finite-rate feedback of the channel state information. We focus our attention on providing capacity analysis of a quantized MISO system over correlated fading channels with sub-optimal and mismatched channel quantizers. Two types of mismatched quantizers are investigated, which include: 1) quantizers...
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