In this paper, we study the performance of multiple-input multiple-output channel estimation methods using training sequences. We consider popular linear least squares (LS) and minimum mean-square-error (MMSE) approaches propose new scaled LS (SLS) relaxed MMSE techniques which require less knowledge second-order statistics and/or have better than conventional estimators. The optimal choice signals is investigated for aforementioned techniques. case multiple estimates, best unbiased (BLUE)...

A serious shortcoming of current downlink power control methods is that their performance may be severely degraded when the channel information known imprecisely at transmitter. In this paper, a computationally and implementationally simple centralized method proposed for cellular wireless communication systems using code division multiple access (CDMA) or space (SDMA). Our provides substantially improved robustness against imperfect knowledge by means maintaining required quality service...

Channel estimation in multiple-input multiple-output (MIMO) wireless communication systems plays a key role the performance of space-time decoders that depends on accuracy channel knowledge. In this paper, we study MIMO using training sequences. The least squares (LS), minimum-mean-square error (MMSE), and new scaled LS (SLS) approaches to are studied optimal choice signals is investigated for each these techniques.

In this paper, we design the training signal for a multi-input multi-output (MIMO) communication system in colored medium. We assume that known channel covariance matrix (CM) is Kronecker product of transmit CM and receive CM. Similarly, additive Gaussian noise modeled by temporal spatial maximize differential entropy gained receiver limited energy budget at transmitter. Using, singular value decomposition involved CMs, turn problem into convex optimization problem. prove left right vectors...

Various methods have been proposed for passive localization by using a network of sensors measuring different parameters such as the angle arrival (AOA), time difference (TDOA), Doppler frequency (FDOA), differential received signal strength (DRSS), gain ratio (GROA), or combination these pieces information. In this paper, method target based on power in multiple stations has two scenarios. one scenario, receiving antennas are omnidirectional and other scenario they directional. We derived...

In mobile communication systems with multisensor antennas at base stations, downlink channel estimation plays a key role because accurate estimates are needed for transmit beamforming. One efficient approach to this problem is probing feedback. method, the station array transmits (training) signals. The then estimated from feedback reports provided by users. This paper studies performance of method using antenna and single-sensor least squares (LS), linear minimum mean square error (LMMSE),...

A large bandwidth wide-slot antenna, fed by coplanar waveguide (CPW), is proposed. Experimental investigations and detailed simulations are conducted to understand its behavior optimize for broadband operation. The impedance bandwidth, determined 10-dB return loss of the proposed slot antenna using both measurement simulation, about 131% (2.8 14GHz). In addition be small in size, has low cross polarization, relatively high gain, it exhibits stable far-fleld radiation characteristics entire...

In this paper, we propose a speech-model based method using the linear predictive (LP) residual of speech signal and maximum-likelihood (ML) estimator proposed in “Blind estimation reverberation time,” (R. Ratnam , J. Acoust. Soc. Amer., 2004) to blindly estimate time (RT <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">60</sub> ). The input is passed through low order coding (LPC) filter obtain LP signal. It proven that unbiased autocorrelation...

Spectrum management policies are responsible for poor utilisation of the radio spectrum. By carrying out dynamic spectrum (DSM), cognitive (CR) can increase in wireless systems efficiently. CR technology accounts improvement significantly. One issue DSM is assignment frequency channels among its users. Herein, a general model and four utility functions optimal channel open such as networks have been defined. First, new function with better fairness than other proposed. Then, two different...

The adaptive radar detection of a point target in the presence signal-dependent interference, also known as system-dependent clutter, is addressed this paper. Here, signal assumed to be an intra-pulse modulated waveform and surrounded by both range frequency spectrum domains. In clutter-dominant situation, problem studied under wide-sense stationary (WSS) non-stationary Gaussian interference processes two closed-form detectors, respectively named WSS-Rao NS-Rao are derived. Both analytically...

This paper discusses the problem of sea target detection in satellite based passive radars. is consequent two main factors. The first factor, which common all radars, that transmitter not under control radar designer and its ambiguity function usually undesirable for use, therefore masked by leakage reference signal, clutter, stronger targets. second more important targets cannot be extracted from clutter Doppler domain due to their close velocity. To overcome these problems, an LS algorithm...

Cognitive Radio (CR) has been regarded as a promising technology to improve the spectrum utilization significantly. One of considered issues in CR is allocation frequency channels between its users. In this paper, at first, model presented, second, new assignment methods based on Artificial Bee Colony (ABC) algorithm proposed. order decrease search space proposed mapping process channel matrix and position bees ABC characteristics availability interference constraints. The Results show our...

This paper proposes a simple and practical passive system for detection direction finding of far-field signal source. The proposed receives emitted from far away source using set similar directional antennas. envelope the received signals are used both to detect existence pulse estimate it's bearing angle. We determine design constraints on employed antennas pattern such that processing algorithm be which operates in wide frequency range at each instant. evaluate required constrains shape...

A new robust power adjustment method is proposed for transmit beamforming in cellular communication systems that use antenna arrays at base stations (BSs). Our provides an improved robustness against imperfect knowledge of the wireless channel by means maintaining required quality service (QoS) worst-case uncertainty.

In wireless communication systems with multiple users, the near-far effect and cochannel interferences decrease spectral efficiency system performance. An efficient known method to combat these destructive effects is properly adjust transmit powers. A practical way for power control (PC) in cellular autonomous distributed PC (DPC). this method, of each link independently modified based on received signal-to-interference-plus-noise ratio (SINR) reported from other side that link. It a perfect...

Capacity of wireless communication systems can be increased enormously using arrays antenna at transmitter and receiver. However, in these so called multi-input multi-output (MIMO) systems, the performance signal detection is tightly related to channel knowledge receiver side. Practically, information subject error because outdated data, quantization error, imperfect estimation/measurement. It known that case knowledge, symbol MIMO communications may severely degrades. The optimum method...

In this paper a multi-input multi-output (MIMO) communication system is considered in which relay with multiple antennas used to assist the data transmission from source destination. We assume that applies linear transform matrix on its received signal vector and retransmit transformed destination node. optimize by maximizing average end-to-end SNR. The transfer related eigenvectors of correlation matrices two channels. For some special cases, we derive optimum solution best unitary...

Estimating the signal direction of arrival (DOA) using a compact system is great interest in various civil, military, airborne, and communication applications. The DOA can be estimated arriving delays at multiple collocated sensors. In this paper, Cramer-Rao bound (CRB) estimation based on measuring time difference by N pairs sensors derived. Then, optimum sensor arrangement for minimizing error obtained finally discrete Fourier transform-based solution estimating presented. Using computer...

Cognitive radio is a technology with tremendous potential for more efficient utilisation of the spectrum. Based on available network side information to secondary user, three transmission models are proposed in literature: 'underlay' method, 'overlay' method and 'hybrid' method. The authors study here capacity power allocation hybrid In particular, investigate ergodic user under joint average interference primary receiver constraints when no channel state except its probability density...

The capability to increase the channel capacity of wireless systems without increasing transmit power depends on accuracy estimation at receiver. In this paper, problem designing training signals is investigated for correlated and uncorrelated multi-input multioutput (MIMO) channels. For this, optimum briefly addressed in sense mean square error. Then signal designed channels by maximizing mutual information (carried signal) between received sequence during training. Simulations show that...

Power control is one of the most efficient approaches to increase capacity and quality service (QoS) in cellular communication systems. Existing power are mostly suitable for environments with quasi-stationary channels, while practice, channel characteristics may vary very fast time. Therefore these do not accurately capture dynamics a real channel. In this paper we propose new method wireless networks Rayleigh fading signals. minimize total transmit subject constraints on outage probability...

In this letter, we consider a power allocation problem for digital subscriber line (DSL) systems. The goal of is to minimize the total transmit under some constraints on minimum data-rate and maximum each modem where take into account various sources interference. We convert our an auxiliary geometric programming (GP) which gives optimum solution powers in neighborhood given feasible point. Then, use iterative scheme obtaining original by exploiting GP problem. Numerical examples show that...

A serious shortcoming of current downlink power adjustment and transmit beamforming methods is that their performance may become severely degraded when the channel correlation (DCC) matrices are known imprecisely at base stations. new method proposed which provides a substantially improved robustness against imperfect knowledge wireless by means maintaining required quality service (QoS) for worst-case uncertainty. Our can be straightforwardly used in conjunction with any existing techniques.