Low-complexity interference variance estimation methods for coded multicarrier systems: application to SFN

For single-frequency network (SFN) transmission, the echoes coming from different transmitters are superimposed at the reception, giving rise to a frequency selective channel. Although multicarrier modulations lower the dispersion, the demodulated signal is sensitive to be degraded by inter-symbol interference (ISI) and inter-carrier interference (ICI). In view of this, we use channel coding in conjunction either with filter bank multicarrier (FBMC) modulation or with orthogonal frequency division multiplexing (OFDM). To deal with the loss of orthogonality, we have devised an interference-aware receiver that carries out a soft detection under the assumption that the residual interference plus noise (IN) term is Gaussian-distributed. To keep the complexity low, we propose to estimate the variance of the IN term by resorting to data-aided algorithms. Experimental results show that regardless of the method, FBMC provides a slightly better performance in terms of coded bit error rate than OFDM, while the spectral efficiency is increased when FBMC is considered.Peer ReviewedPostprint (published version

D13.2 Techniques and performance analysis on energy- and bandwidth-efficient communications and networking

Deliverable D13.2 del projecte europeu NEWCOM#The report presents the status of the research work of the various Joint Research Activities (JRA) in WP1.3 and the results that were developed up to the second year of the project. For each activity there is a description, an illustration of the adherence to and relevance with the identified fundamental open issues, a short presentation of the main results, and a roadmap for the future joint research. In the Annex, for each JRA, the main technical details on specific scientific activities are described in detail.Peer ReviewedPostprint (published version

D13.3 Overall assessment of selected techniques on energy- and bandwidth-efficient communications

Deliverable D13.3 del projecte europeu NEWCOM#The report presents the outcome of the Joint Research Activities (JRA) of WP1.3 in the last year of the Newcom# project. The activities focus on the investigation of bandwidth and energy efficient techniques for current and emerging wireless systems. The JRAs are categorized in three Tasks: (i) the first deals with techniques for power efficiency and minimization at the transceiver and network level; (ii) the second deals with the handling of interference by appropriate low interference transmission techniques; (iii) the third is concentrated on Radio Resource Management (RRM) and Interference Management (IM) in selected scenarios, including HetNets and multi-tier networks.Peer ReviewedPostprint (published version

D13.1 Fundamental issues on energy- and bandwidth-efficient communications and networking

Deliverable D13.1 del projecte europeu NEWCOM#The report presents the current status in the research area of energy- and bandwidth-efficient communications and networking and highlights the fundamental issues still open for further investigation. Furthermore, the report presents the Joint Research Activities (JRAs) which will be performed within WP1.3. For each activity there is the description, the identification of the adherence with the identified fundamental open issues, a presentation of the initial results, and a roadmap for the planned joint research work in each topic.Preprin

Comparison of linear and widely linear processing in MIMO-FBMC systems

This paper carries out a comparison between two multi-stream techniques aimed for filter bank multicarrier (FBMC) systems based on the offset quadrature amplitude modulation (OQAM). The first option performs linear processing (LP) and, therefore, it does not take into account the non-circularity property of the transmitted symbols. The second technique considers the FBMC specificities and performs widely linear processing (WLP). With the aim of predicting which solution gives the best performance we have conducted a theoretical analysis that reveals that the technique based on the LP is able to achieve the lowest sum mean square error (MSE) at high SINR in channels with high coherence bandwidth. This holds true when the number of streams (S), and the number of transmit antennas (NT) and receive antennas (NR) are related as follows S = NR = 3, NT = NR. The numerical results show that the LP also gives the best performance in terms of BER if the aforementioned inequality is satisfied and the channel coherence bandwidth is substantially larger than the subcarrier spacing. If not, then the LP exhibits an error floor and the WLP may give better performance, especially at low noise regime.Peer Reviewe

A suboptimal power allocation algorithm for FBMC/OQAM

This paper tackles the sum-rate maximization in FBMC systems. It is well-known that multipath fading destroys the orthogonality of the subcarriers, which brings a non-convex problem that can be interpreted as the maximization of a difference of concave functions. This reformulation enables using DC programming to find the global optimal but the complexity becomes unaffordable in the FBMC context. Aiming at reducing the complexity we have devised a new suboptimal algorithm. The idea consists in smartly partitioning the band into three subsets so that subcarrier signals belonging to the same subset do not overlap in the frequency domain. If subsets maximize sequentially their own rate the original problem is turned into three simpler problems. Simulation-based results show that the sum-rate is in the same order as the water-filling used in OFDM and a suboptimal solution based on DC programming. However, the addressed technique enables saving up to 25% of the power at SNR=22 dB.Peer Reviewe

SDMA for filterbank with Tomlinson Harashima precoding

Several studies have revealed that OFDM is outperformed in several areas by the filter bank based multicarrier (FBMC) modulation thanks to pulse shaping techniques. Nevertheless, the combination of FBMC with multi-antenna architectures is nontrivial. Aiming at making progress towards this direction we study MIMO precoding techniques for the MISO broadcast channel (MISO-BC). Due to its superior performance over linear precoding techniques we have focused on the spatial Tomlinson Harashima precoder (STHP). The analysis carried out in this paper concludes that the conventional STHP performs poorly when it is combined with FBMC systems since it is not able to cope with ISI and ICI. To combat the interferences we propose a novel subband processing based on the STHP concept. The numerical results show that FBMC and OFDM almost give the same performance in terms of BER. However, FBMC is able to achieve spectral efficiency values that are 31% higher in comparison to the ones obtained in OFDM when 20% of the symbol duration corresponds to the cyclic prefix.Peer ReviewedPostprint (published version

An evaluation of thermal plasmas in pyrometallurgy

SIGLEAvailable from British Library Document Supply Centre- DSC:DX77502 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Subcarrier allocation and power loading strategies for multi-user broadcast FBMC/OQAM systems

With the objective of maximizing the sum-rate this paper tackles the subcarrier and the power allocation problems in the context of multi-user FBMC. Under highly frequency selective channels the demodulated data is affected by ISI and ICI. As a solution the band is partitioned into three sub- sets so that there is no overlapping between the subcarriers of the same subset. Then we propose a low complexity heuristic to carry out the resource allocation over each sub- set. Simulation-based results demonstrate that at low noise regime, the proposed solution is able to outperform the con- ventional approachPeer ReviewedPostprint (published version

Experimental performance bounds of MIMO-FBMC/OQAM systems

This paper addresses the application of filter bank multicarrier (FBMC) systems to multiple-input-multiple-output (MIMO) channels. In particular, it is investigated the FBMC modulation based on OQAM, known as FBMC/OQAM. Existing solutions reveal that FBMC/OQAM remains competitive with the orthogonal frequency division multiplexing (OFDM) technique when the number of streams (S), transmit antennas (NT) and receive antennas (NR) are related as follows: S = min(NT,NR). State-of-the-art techniques fail to achieve satisfactory results in FBMC/OQAM systems when S < min(NT,NR). That is because the strongest spatial subchannels exhibit higher gains in MIMO-OFDM than in existing MIMO-FBMC/OQAM systems. To determine if FBMC/OQAM can be successfully applied when strict inequality holds, this paper provides experimental performance bounds, which can be assumed to approximate the optimal performance. In this sense, numerical results show that FBMC/OQAM is able to slightly outperform OFDM when S < min(NT,NR) by attenuating the residual interference 20 dB below the equalized noise. This insightful information could be used in the design process of future techniques to approach the experimental performance bounds.Postprint (published version