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Minimum variance beamformers are usually complemented with diagonal loading techniques in order to provide robust ness against finite sample size effects. In spite of its usefulness and popularity, some of the insights of this interesting technique have remained inconspicuous for decades. This work presents a new asymptotic performance study that will shed(More)
Space-time block coding (STBC) is a widely studied transmitter diversity scheme able to increase the capacity of the scatter wireless channel. Most of the existing detection techniques at the receiver assume perfect channel knowledge, requiring the use of training sequences. Independent component analysis (ICA) neural networks are a class of non-trained(More)
In this paper, we study the ergodic capacity of a multiple input multiple output (MIMO) uncorrelated flat fading channel with perfect channel state information at the receiver and partial channel state information at the transmitter. We focus our attention on the case where the transmitter is informed only with the modulus of the channel matrix(More)
In this paper, we study a family of robust power allocation techniques for multi-input multi-output communication systems with incomplete channel state information at the transmitter side. Precisely, we focus our attention to the case where the transmitter has access only to the modulus of the channel coefficients. We present the robust techniques under two(More)
A multibeam satellite scenario is considered along this paper to test for the benefits of dual polarization. Several multiple input multiple output (MIMO) transmitting schemes are proposed to deal with the dual polarization, where the results show that dual polarization is better employed as an interference rejection tool.
In this work, we study a downlink communications scheme, focusing our attention on the case where the base station is equipped with multiple antennas and transmits information simultaneously to a certain number of users with single antenna terminals. We consider a realistic scenario where an imperfect estimate of the actual channel is available at both(More)
In this work, we study different capacity formulations in multi-input multi-output channels where the transmitter is only informed with the magnitude of the complex channel matrix coefficients. Perfect channel knowledge is assumed at the receiver side. First, we give the expressions for the ergodic, compound, and outage capacities for our particular model(More)
One of the multiple advantages of communicating through MIMO systems is their inherent ability to provide flexible configurations. Following this line of thought, in this paper we present a generic framework to study the degrees of freedom in the design of MIMO communication systems (e.g.: code length, number of multiplexed streams, or receiver structure).(More)
In this article, a novel robust image watermarking scheme based on the combination of discrete cosine transform (DCT) and independent component analysis (ICA) is proposed. Firstly, the original image is transformed by using block-based DCT and then the DC coefficients of the image in every block are picked out. These DC coefficients are mixed linearly with(More)
This paper deals with the problem of the design of a multi-antenna system assuming that only a statistical channel knowledge is available at the transmitter. More precisely, in the proposed design it is considered that an optimum maximum likelihood detector is employed at the receiver side and that the channel has a line of sight component. The design is(More)