Jon Altuna

Analysis of ICI compensation for DVB-T2

This paper analyzes the impact of inter-carrier interference (ICI) compensation on the physical layer of DVB-T2, the new digital terrestrial television standard. We compare the performance of a well-known low complexity soft demapper for different time-interleaving depths and code rates in several realistic mobile scenarios. This paper further presents an iterative receiver design that exchanges extrinsic information between the low-density parity-check (LDPC) decoder and the ICI canceller in order to improve performance. Provided simulation results show that the proposed ICI cancellation algorithms can be necessary in several DVB-T2 transmission modes when the length of the time interleaver is limited.

Application of Higher-order Statistics on Rolling Element Bearings Diagnosis

The aim of this work is to evaluate, in a theoretical sense, the current application of bispectrum on rolling element bearings diagnosis. A mathematical model of the vibration generated by defective rolling element bearings is used and substituted into bispectrum formulas. This work demonstrated that using this statistical tool in order to detect a local fault on rolling element bearings is not effective, contrasting with practical results achieved in other papers. In that sense, some arguments concerning such a contradiction are exposed.

Low-Complexity Detection of Full-Rate SFBC in BICM-OFDM Systems

Last-generation and future wireless communication standards, such as DVB-T2 or DVB-NGH, are including multi-antenna transmission and reception in order to increase bandwidth efficiency and receiver robustness. The main goal is to combine diversity and spatial multiplexing in order to fully exploit the multiple-input multiple-output (MIMO) channel capacity. Full-rate full-diversity (FRFD) space-time codes (STC) such as the Golden code are studied for that purpose. However, despite their larger achievable capacity, most of them present high complexity for soft detection, which hinders their combination with soft-input decoders in bit-interleaved coded modulation (BICM) schemes. This article presents a novel low-complexity soft detection algorithm for the reception of FRFD space-frequency block codes in BICM orthogonal frequency-division multiplexing (OFDM) systems. The proposed detector maintains a reduced and fixed complexity, avoiding the variable nature of the list sphere decoder (LSD) due to its dependence on the noise and channel conditions. Complexity and simulation-based performance results are provided which show that the proposed detector performs close to the optimal log-maximum a posteriori (MAP) detection in a variety of DVB-T2 broadcasting scenarios.

Performance comparison of OFDM and FDE single-carrier modulation for spatial multiplexing MIMO systems

Multiple-input multiple-output (MIMO) signal processing combined with orthogonal frequency division multiplexing (OFDM) is a widely accepted solution to achieve the high bit rates that new communication standards require in frequency-selective wireless channels. In recent years, a new frequency-domain equalized (FDE) cyclic-prefixed single-carrier (CPSC) block transmission system has been proven to achieve similar performance to OFDM for coded systems with the same overall complexity, avoiding its main drawbacks and becoming a candidate for future wireless standards. A FDE CPSC spatial multiplexing system is analyzed and compared to OFDM. The implementation of different frequency-domain MIMO equalization and detection schemes is evaluated. Simulation-based performance results prove the efficiency of FDE CPSC based spatial multiplexing systems and highlight that these transmission schemes can outperform OFDM in uncoded and high coding rate MIMO systems, as it has been shown in the literature for the SISO case.

Low-complexity detection of golden codes in LDPC-coded OFDM systems

Recent and next-generation wireless broadcasting standards, such as DVB-T2 or DVB-NGH, are considering distributed multi-antenna transmission in order to increase bandwidth efficiency and signal quality. Full-rate full-diversity (FRFD) space-time codes (STC), such as the Golden code, have been reported to be excellent candidates, being their main drawback their detection complexity, which is enhanced when soft output is required when combined with a bit-interleaved coded modulation (BICM) scheme based on low-density parity check (LDPC) codes. We present a novel low-complexity soft detection algorithm for the reception of Golden codes in LDPC-based orthogonal frequency-division multiplexing (OFDM) systems. Complexity and simulation-based performance results are provided which show that the proposed detector performs close to the optimal detector in a variety of DVB-T2 broadcasting scenarios.

Joint Source-Channel Decoding ASIP Architecture for Sensor Networks

In a sensor network, exploiting the correlation among different sources allows a significant reduction of the transmitted energy at the cost of a complex decoder scheme. This paper introduces the first hardware implementation for joint source-channel decoding of correlated sources. Specifically, a dual-clustered VLIW processor with a highly optimized datapath is presented.

On the Application of Cumulant-based Cyclostationary Processing on Bearings Diagnosis

A false indication of failure in rolling element bearings can be reached when cyclostationary processing technique is used for machine condition diagnosis. This problem is due to the fact that the estimated second-order cyclostationary parameters can be altered by first-order cyclostationary signals such as vibrations no related to those produced by defective bearings. The goal of this work is to solve this problem by applying a cumulant-based approach. Four algorithms were implemented. In order to quantify the effectiveness of the algorithm applications, a new function, named Interference Rate Function, is proposed. The appreciable interference immunity in the estimated cumulant-based cyclostationary parameters demonstrated the veracity of the hypothesis.