Ruben de Francisco

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The problem of joint linear beamforming and scheduling in a MIMO broadcast channel is considered. We show how orthogonal linear beamforming (OLBF) can be efficiently combined with a low-complexity user selection algorithm to achieve a large portion of the multiuser capacity. The use of orthogonal transmission enables the transmitter to calculate exact(More)
The increasing number of sensors deployed in cars calls for new design approaches in intra-vehicle electronic control unit (ECU) networks. ZigBee wireless sensor networks are seen as a good candidate technology, since they can provide high-performance short-range communication with low power consumption, as well as mesh networking capabilities. One of the(More)
We consider a downlink channel where a base station equipped with M transmit antennas communicates with K ≥ M single-antenna receivers and has partial channel knowledge obtained via a limited rate feedback channel. We propose scalar feedback metrics that provide an estimate of the received signal-to-noise plus interference ratio (SINR), which are(More)
This paper addresses the problem of linear beamforming design in MIMO broadcast channels. An iterative optimization method for unitary beamforming is proposed, based on successive optimization of Givens rotations. Under the assumption of perfect channel state information at the transmitter (CSIT) and for practical average signal-to-noise ratios (SNR), the(More)
An iterative optimization method for unitary beamforming in MIMO broadcast channels is proposed, based on successive optimization of Givens rotations. Under the assumption of perfect channel state information at the transmitter (CSIT) and for practical average SNR values, the proposed technique provides higher sum rates than zero forcing (ZF) beamforming(More)
Recent advances in ultra-low-power circuits and energy harvesters are making self-powered body wireless autonomous transducer solutions (WATS) a reality. Power optimization at the system and application level is crucial in achieving ultra-low-power consumption for the entire system. This paper deals with innovative WATS modeling techniques, and illustrates(More)
In order to avoid packet collisions in wireless communications, cognitive radio users require spectrum sensing to increase their awareness. Spectrum sensing methods must show good performance with low complexity, particularly in low-power wireless sensor networks. Motivated by the non-continuous signal patterns observed from realistic signals, an adaptive(More)
The increasing use of wireless networks and the constant miniaturization of electronic devices have empowered the development of wireless body area networks (WBAN). In this paper, we focus on the coexistence problem of WBAN and wireless LAN (WLAN) in medical environments. In order to resolve the unfairness issue caused by coexistence, we propose a novel(More)
Wake-up radio technology is a means to improve energy efficiency in low-power wireless sensor networks. In such radios, low-power low-complexity designs are considered, often based on narrow-band transmission, simple modulation techniques, noncoherent detection and matched filter receivers. In order to improve the performance of wake-up radios in(More)