A.I. Perez-Neira

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Optimizing a communication of a Q-antenna access point (AP) with K single antenna terminals is not straightforward. Since a global optimization might not be solvable in real time, the AP has several alternatives involving both the physical layer, e.g. beam-forming and power/bit allocation, and the DLC, such as scheduling. The purpose of this paper is(More)
This paper evaluates the applicability of MIMO techniques to satellite networks in order to achieve diversity and multiplexing gain through dual polarized antennas. In single satellite scenarios the proposed STTC and OSTBC techniques proposed offer better BER than plain stream multiplexing along each polarizations and SISO transmissions. By adding a(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.
We address the energy efficiency analysis for the two-sources cooperative multi-access channel and investigate the impact of usual practical constraints. Specifically, we take into account constraints on the transmission/reception duplexing and on the synchronization between sources. Assuming a total network energy, we define and compute the maximum(More)
While almost all cooperative studies focus on the rate increase that relaying networks provide to the system, this paper shows the benefit of cooperation in terms of two potential quality of service (QoS) system measures: fairness and delay. A cooperative multiple-access channel (MAC) protocol is proposed based on round robin scheduling. With it, network(More)
In this paper, an achievable rate per unit energy is obtained for a multiple relay Gaussian network, where transmissions are over orthogonal channels. A single source transmits to a single destination helped by multiple-hop relay transmissions. A regenerative relaying function is employed at the relays that, instead of trying to decode the source(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)
We consider the orthogonal multiple relay channel at the low SNR regime. The source transmits to the destination and all the possible relays in one channel and the relays transmit in different and orthogonal channels making use of the transmission received from the source. This cooperative strategy achieves diversity gains at a high cost in bandwidth(More)