Browsing by Author "Mendicute, Mikel"
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Item Design, simulation and hardware validation of a low-cost CLMS echo canceling system(2009) Prieto, Pablo; Sanchez, Mikel; Ser, Javier Del; Mendicute, Mikel; POWERTRAIN; GENERAL; IAThis paper presents the design, simulation and performance of a low-cost echo canceler for its application to on-channel repeaters in single frequency DVB-T networks. In these devices an echo canceler is required in order to avoid the coupling echoes produced between transmission and reception antennas. The designed echo canceler is based on an adaptive FIR Alter where a correlation-based LMS algorithm (namely, CLMS) is used for updating the set of complex coefficients under a Minimum Squared Error (MSE) criteria. The implemented prototype includes an Analog Devices floating-point DSP and a Virtex II Pro FPGA core. Computer simulation results and the registered in-lab measurements of the prototype verify that our approach shows surprisingly satisfactory echo attenuation capabilities at a minimal computational cost.Item Design, simulation and implementation of a channel equalizer for DVB-T on-channel repeaters(2008) Mendicute, Mikel; Sobrón, Iker; Ser, Javier Del; Prieto, Pablo; Isasi, Ricardo; POWERTRAINThis article describes the design and implementation of a channel equalizer for a terrestrial digital television (Digital Video Broadcasting-Terrestrial, DVB-T) on-channel repeater, namely gap-filler. Two are the benefits of including this equalizer in a repeater setup: on one hand, the transmitted signal requires a lower dynamic range and its degradation becomes smaller at the output amplifiers, thus allowing for a higher transmit power for the same modulation error rate (MER). On the other hand, it eases the equalization and decoding processes at the final receiver by improving its operation conditions. In this context, we present a novel low-cost equalizer architecture for mid-range and domestic gap-fillers. The design, implementation and validation methodology is also described, from the initial Matlab and Advanced Design System (ADS) simulations to the final hardware implementation, based on a field programmable gate array (FPGA) device and a Blackfin digital signal processor (DSP). The obtained practical results assess the performance gains predicted by simulation, hence proving the validity and efficacy of the designed equalizer to reduce the cost of the amplifiers and to obtain a better signal quality at the final user's receiver.Item Fixed-complexity regularized vector precoding for the multiuser MIMO downlink channel(2009) Barrenechea, Maitane; Thompson, John S.; Mendicute, Mikel; Del Ser, Javier; IAA fixed-throughput vector precoding (VP) approach specially suitable for hardware implementation in field programmable gate array (FPGA) devices is presented in this paper. The algorithm, which is based on the sphere encoder (SE), is divided into two main stages: at the preprocessing stage, the columns of the precoding matrix are ordered following any of the ordering approaches that have been proposed in this paper. Secondly, the search tree is configured so as to yield an appropriate bit error rate (BER) performance. Simulation results show that the BER performance of the proposed algorithm is very close to that of the SE, whereas its complexity is significantly smaller.Item Joint source-channel-network decoding and blind estimation of correlated sensors using concatenated zigzag codes(2009) Del Ser, Javier; Mendicute, Mikel; Crespo, Pedro M.; Gil-Lopez, Sergio; Olabarrieta, Ignacio; IAFocusing on densely deployed wireless sensor networks, this paper presents a novel method for joint source-channel-network coding of distributed correlated sources through multiple access relay channels. In such networks, the role of intermediate sensors as relay nodes permits to achieve enhanced end-to-end error performance and increased spatial diversity in presence of channel fading. This paper addresses this scenario for a two source, single relay architecture by proposing a novel coding approach based on concatenated Zigzag codes, whose low complexity is specially suitable for energy-constrained autonomous systems. Joint decoding and estimation of the parameters defining the correlation between sensors is iteratively performed at the receiver side. Simulation results show that the proposed joint coding scheme attains significant energy gains with respect to traditional routing techniques, specially at high signal to noise ratios.