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In this paper, the well known Zadeh’s series representation of a linear periodically time varying system is exploited to develop linear equalization techniques for narrowband powerline communications based on orthogonal frequency division multiplexing. Numerical and experimental results referring to the band 200–500 kHz evidence that a coherent receiver exploiting the proposed equalizers can significantly outperform both its counterpart based on conventional channel estimation/equalization techniques and differential detection with a limited complexity. This leads to the conclusion that a coherent receiver incorporating the proposed equalization techniques represents a technically appealing solution for narrowband high data rate powerline communications in indoor scenarios. [ABSTRACT FROM PUBLISHER]

The problem of bit and power loading for bit rate maximization in orthogonal frequency division multiplexing data communications over indoor powerline channels is investigated, and a simple method for bit/power allocation in half a cycle of the mains is developed. The proposed solution is based on the so-called Zadeh’s representation for modeling the linear periodically time-varying behavior of powerline channels. Numerical results show the superiority of the proposed method over other solutions available in the technical literature in a real-world scenario. [ABSTRACT FROM AUTHOR]

In this paper, the impact of statistical noise modelling on the error performance achieved by orthogonal frequency-division multiplexing (OFDM) over indoor broadband power-line channels is investigated. Different classes of statistical models suitable to represent power-line noise are illustrated and their impact on the error performance of a specific OFDM system is assessed via computer simulations. Numerical results are compared with the error performance provided by the same system in the presence of measured power-line noise; this is evidence that a realistic indication of error performance can be achieved only if the power spectral density of the adopted noise model exhibits a good match with that of the measured noise. In practice, this result can be achieved by modeling the power-line noise as a moving average random process of proper order; however, a satisfying match can be achieved as well if other simple noise models available in the technical literature are adopted. [ABSTRACT FROM AUTHOR]

Indoor powerline channels usually exhibit a cyclic input–output behavior due to the time-varying impedance of power loads. This makes typical time-invariant system models unsuitable to provide a faithful representation of such channels. In this paper, starting from the so-called Zadeh's series expansion, a discrete-time parametric representation of a linear periodically time-varying system is developed, and it is shown how a reduced-complexity version of it can be adopted to model indoor powerline channels. Then, various methods for estimating the parameters of the proposed representation are developed and compared in terms of performance and complexity. Numerical results evidence that our reduced complexity model is able to provide an accurate representation of indoor powerline channels and is of practical interest for both smart-grid applications and home area networks. [ABSTRACT FROM AUTHOR]

The accuracy of indoor wireless localization systems can be substantially enhanced by map-awareness, i.e., by the knowledge of the map of the environment in which localization signals are acquired. In fact, this knowledge can be exploited to cancel out, at least to some extent, the signal degradation due to propagation through physical obstructions, i.e., to the so called non-line-of-sight bias. This result can be achieved by developing novel localization techniques that rely on proper map-aware statistical modelling of the measurements they process. In this manuscript a unified statistical model for the measurements acquired in map-aware localization systems based on time-of-arrivaland received signal strength techniques is developed and its experimental validation is illustrated. Finally, the accuracy of the proposed map-aware model is assessed and compared with that offered by its map-unaware counterparts. Our numerical results show that, when the quality of acquired measurements is poor, map-aware modelling can enhance localization accuracy by up to 110% in certain scenarios. [ABSTRACT FROM PUBLISHER]

Estimating the input-output behavior of low voltage powerline channels for indoor high speed data communications requires the availability of proper wideband channel sounding tools. In fact, the properties of real world powerline channels are substantially different from those commonly exhibited by their wireless counterparts, so that standard methods for wireless channel sounding cannot be adapted to a powerline scenario. In this paper, after providing some general design guidelines for powerline channel sounding, a detailed description of a FPGA-based implementation of a wideband powerline channel sounder is provided. Such a tool is based on low cost hardware and is flexible, since it can be easily customized to user needs using a set of simple graphical user interfaces. Some of its specific applications, namely the estimation of the time-varying transfer function of an indoor powerline channel and the evaluation of the power spectral density of the noise affecting it, are illustrated to show the potentialities of the developed equipment. [ABSTRACT FROM PUBLISHER]

Establishing bounds on the accuracy achievable by localization techniques represents a fundamental technical issue. Bounds on localization accuracy have been derived for cases in which the position of an agent is estimated on the basis of a set of observations and, possibly, of some a priori information related to them (e.g., information about anchor positions and properties of the communication channel). In this paper, new bounds are derived under the assumption that the localization system is map-aware, i.e., it can benefit not only from the availability of observations, but also from the a priori knowledge provided by the map of the environment where it operates. Our results show that: a) map-aware estimation accuracy can be related to some features of the map (e.g., its shape and area) even though, in general, the relation is complicated; b) maps are really useful in the presence of some combination of low SNRs and specific geometrical features of the map (e.g., the size of obstructions); c) in most cases, there is no need of refined maps since additional details do not improve estimation accuracy. [ABSTRACT FROM AUTHOR]

In this paper, novel equalization algorithms for continuous phase modulations (CPMs) are illustrated. Both conventional (linear and decision-feedback) and turbo equalization techniques are derived using the Laurent decomposition of CPM signals. All of them operate in the frequency domain and process two samples of the received signal per channel symbol. Numerical results show that on one hand, conventional equalization strategies offer good performance for binary partial response signaling over severely frequency-selective wireless channels at a moderate complexity. On the other hand, there is evidence that turbo techniques provide a small energy saving at the price of a substantial computational burden. [ABSTRACT FROM AUTHOR]

In this paper, channel equalization algorithms processing two samples of the received signal per channel symbol and operating in the frequency domain are described in a unifying framework. First, minimum mean-square error linear and decision-feedback equalizers are derived, and a synthesis technique based on the well-known Levinson-Durbin algorithm is proposed for the latter. Then, iterative linear and decision-feedback equalization algorithms for turbo processing are devised. Performance results for both uncoded and coded phase-shift keying transmissions show the efficacy of the proposed equalization techniques and their superiority over other existing frequency-domain equalization strategies. [ABSTRACT FROM AUTHOR]

In this paper, a novel feedback frequency synchronizer for orthogonal frequency-division multiplexing signals transmitted over multiparty fading channels is described. Its derivation is based on maximum-likelihood estimation techniques and assumes an approximate statistical knowledge of the communication channel. The performance of the proposed algorithm is assessed by computer simulation, and is compared with that provided by other synchronization algorithms and with Cramer-Rao bounds. [ABSTRACT FROM AUTHOR]

Multiple-input multiple-output (MIMO) wireless systems are of interest due to their ability to provide substantial gains in capacity and quality. This paper proposes equal gain transmission (EGT) to provide diversity advantage in MIMO systems experiencing Rayleigh fading. The applications of EGT with selection diversity combining, equal gain combining, and maximum ratio combining are addressed. It is proven that systems using EGT with any of these combining schemes achieve full diversity order when transmitting over a memoryless, fiat-fading Rayleigh matrix channel with independent entries. Since, in practice, full channel knowledge at the transmitter is difficult to realize, a quantized version of EGT is proposed. An algorithm to construct a beamforming vector codebook that guarantees full diversity order is presented. Monte-Carlo simulation comparisons with various beamforming and combining systems illustrate the performance as a function of quantization. [ABSTRACT FROM AUTHOR]

Focuses on a study which devised soft-in soft-out algorithms for symbol detection over frequency-flat Rayleigh fading channels. Algorithm for maximum a posteriori detection over frequency-flat channels; Results; Conclusion.

Presents a study which investigated optimum one-shot detection over known and partially known doubly selective Rayleigh fading channels. Description of the communications system model; Definition of partially matched detectors for doubly selective fading channels; Numerical results and conclusions.

Presents a novel two-stage noncoherent receiver for interleaved trellis-coded CPSFK signals transmitted over time-selective channels. Information on the novel noncoherent algorithm; Estimation and tracking of the channel parameters; Simulation results and conclusions.

Presents information on a study which assessed the performance of symbol-by-symbol differential detection algorithms for minimum-shift keying signals transmitted over additive white Gaussian noise (AWGN) and frequency-flat Rayleigh fading channels. Methodology; Chanel and signal models; Differential detection for the AWGN channel.

Focuses on a study that examined the differential detection of phase-shift keying (PSK) signals transmitted over frequency-flat fading channels using linearity time-varying fading models. Mathematical model used for the fading process and the notation of signal models; Differential detection of PSK signals; Computation of the bit error rate of the double-filter detector; Simulation results.

Estimates the error performance of noncoherent detection receivers for frequency-shift keying (FSK) signals. Mathematical model of the communication system; Error bounds for orthogonal M-ary FSK; Error performance of binary FSK.

Highlights a study which used blind detection schemes to observe continuous phase modulation (CPM) signals which were transmitted across frequency flat fading channels. Feature of the blind detector; Assessment of the blind detector's error rate performance; Details on maximum-likelihood detection; Information on blind detection; Method used to conduct the study; Results of the study.

Investigates noncoherent detection of frequency-shift keying (FSK) signals transmitted over frequency-flat fading channels using a linearly time-varying fading models. Description of mathematical model of the fading process; Basic notations for FSK signals; Method for computing the error probability of a conventional FSK noncoherent detector in fast fading.

Discusses the use of a per-survivor phase-tracking algorithm for phase-shift-keyed signals transmitted over channels with phase jitter. Description of the received signal model; Phase-estimation in per-survivor processing receivers; Information on an expectation maximization-based phase estimator.

Proposes novel nondata-aided algorithms for joint estimation of timing and carrier phase in minimum-shift keying-type modulations. Timing and carrier phase estimation; Simulation results.

In this paper, a novel ultrawideband system for multiuser data communications is proposed. In this system multiple users are allowed to transmit on-off keying modulated signals in the same time intervals and exploiting the same frequency subband. Time/frequency overlapped data frames sent by distinct users include low data rate training sequences characterized by different repetition periods. This transmission strategy, known as rate division multiple access in the technical literature, allows to ease two fundamental tasks at the receive side, namely joint channel estimation and timing synchronization. Channel estimates are exploited by a multiuser detector based on a zero forcing equalizer. Numerical results evidence that the proposed solution yields good error performance at the price of a limited complexity. [ABSTRACT FROM PUBLISHER]

In this paper, the problem of node management in the presence of randomized cooperation is tackled. First, game theory is exploited to model the problem of setting up a cluster of cooperative nodes in a wireless network as a multiplayer noncooperative game. In this game the set of players is made of all the nodes belonging to a potential relay cluster an d the set of actions for each player consists of two options only (characterized by different payoffs), namely transmitting a data packet or remaining silent. Then, a novel strategy for the management of node participation to a distributed cooperative link is derived. The proposed solution is fully distributed, is characterized by autonomous choices made by each potential relay and is of significant practical interest since it guarantees the participation of a proper number of nodes to a virtual antenna array (so avoiding an energy waste associated with an excessive number of cooperating nodes) without requiring any overhead for node management. [ABSTRACT FROM PUBLISHER]