Heterogeneous pipelined square-root Kalman Filter algorithm for the MMSE-OSIC problem

The final publication is available at Springer via http://dx.doi.org/10.1007/s11227-009-0354-x[EN] This paper describes a pipelined parallel algorithm for the MMSE-OSIC decoding procedure proposed in V-BLAST wireless MIMO systems, for heterogeneous networks of processors. It is based on a block version of the square-root Kalman Filter algorithm that was initially devised to solve the RLS problem. It has been parallelized in a pipelined way obtaining a good efficiency and scalability. The optimum load balancing for this parallel algorithm is dynamic, but we derive a static load balancing scheme with good performance. © 2009 Springer Science+Business Media, LLC.This work has been supported by the Generalitat Valenciana, project 20080811, by the Universidad Politecnica de Valencia, project 20080009, by the Conserjería de Educacion de la Región de Murcia (Fundacion Séneca, 08763/PI/08), and by the Ministerio de Ciencia e Innovacion (TIN2008-06570-C04-02).Martínez Zaldívar, FJ.; Vidal Maciá, AM.; Giménez Cánovas, D. (2011). Heterogeneous pipelined square-root Kalman Filter algorithm for the MMSE-OSIC problem. Journal of Supercomputing. 58(2):235-243. https://doi.org/10.1007/s11227-009-0354-xS235243582Foschini GJ (1996) Layered space-time architecture for wireless communications in a fading environment when using multiple antennas. Bell Labs Techn J 1:41–59Hassibi B (2000) An efficient square-root algorithm for BLAST. In: IEEE international conference on acoustics, speech and signal processing 2000, vol 2, pp II737–II740Zhu H, Lei Z, Chin FPS (2004) An improved square-root algorithm for BLAST. IEEE Signal Process Lett 11(9)Choi Y-S, Voltz PJ, Cassara FA (2001) On channel estimation and detection for multicarrier signals in fast and selective Rayleigh fading channels. IEEE Trans Commun 49(8)Burg A, Haene S, Perels D, Luethi P, Felber N, Fichtner W (2006) Algorithm and VLSI architecture for linear MMSE detection in MIMO-OFDM systems. In: Proceedings of the IEEE int symp on circuits and systems, May 2006Martínez Zaldívar FJ (2007) Algoritmos paralelos segmentados para los problemas de Mínimos Cuadrados Recursivos (RLS) y de Detección por Cancelación Ordenada y Sucesiva de Interferencia (OSIC). PhD thesis, Facultad de Informática, Universidad Politécnica de Valencia, SpainSayed AH, Kailath T (1994) A state-space approach to adaptive RLS filtering. IEEE Signal Process Mag 11(3):18–60Kumar V, Gram A, Gupta A, Karypis G (2003) An introduction to parallel computing: design and analysis of algorithms, Chap 4, 2nd edn. Addison-Wesley, Harlow

Exploiting disorder for perfect focusing

We demonstrate experimentally that disordered scattering can be used to improve, rather than deteriorate, the focusing resolution of a lens. By using wavefront shaping to compensate for scattering, light was focused to a spot as small as one tenth of the diffraction limit of the lens. We show both experimentally and theoretically that it is the scattering medium, rather than the lens, that determines the width of the focus. Despite the disordered propagation of the light, the profile of the focus was always exactly equal to the theoretical best focus that we derived.Comment: 4 pages, 4 figure

Channel Capacities for Different Antenna Arrays with Various Transmitting Angles in Tunnels

[[abstract]]This paper focuses on the research of channel capacity of multiple-input multipleoutput (MIMO) system with different transmitting angles in straight and curvy tunnels.Araytracing technique is developed to calculate channel frequency responses for tunnels, and the channel frequency response is further used to calculate corresponding channel capacity. The channel capacities are calculated based on the realistic environment. The channel capacities of MIMO long term evolution system using spatial and polar antenna arrays by different transmitting angles are computed. Numerical results show that, The channel capacity for transmitting angle at 15◦ is largest compared to the other angles in the tunnels. Moreover, the channel capacity of polar array is better than that of spatial array both in the straight and curvy tunnels. Besides, the channel capacity for the tunnels with traffic is larger than that without traffic. Finally, it isworth noting that in these cases the presentwork provides not only comparative information but also quantitative information on the performance reduction.[[notice]]補正完畢[[incitationindex]]SC

Spatial Modulation or Spatial Multiplexing for mmWave Communications?

In this paper, two large scale (LS)–multiple–input multiple–output (MIMO) systems and their performance over 3D statistical outdoor millimeter wave (mmWave) channel model are considered and thoroughly analyzed. Namely, spatial multiplexing (SMX) and spatial modulation (SM) systems are considered. The performance of both systems in terms of average bit error ratio (ABER) and channel capacity are derived and studied. Obtained results divulge that SM can achieve higher theoretical capacity than SMX system. Further, SMX system is shown to offer better ABER and mutual information performance as compared to SM system for the same system configuration. Yet, SM demonstrate significant energy efficiency (EE) enhancement for large scale number of transmit antennas.© 2019 Springer. ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering.fi=vertaisarvioitu|en=peerReviewed

Novel precoded relay-assisted algorithm for cellular systems

Cooperative schemes are promising solutions for cellular wireless systems to improve system fairness, extend coverage and increase capacity. The use of relays is of significant interest to allow radio access in situations where a direct path is not available or has poor quality. A data precoded relay-assisted scheme is proposed for a system cooperating with 2 relays, each equipped with either a single antenna or 2-antenna array. However, because of the half-duplex constraint at the relays, relaying-assisted transmission would require the use of a higher order constellation than in the case when a continuous link is available from the BS to the UT. This would imply a penalty in the power efficiency. The simple precoding scheme proposed exploits the relation between QPSK and 16-QAM, by alternately transmitting through the 2 relays, achieving full diversity, while significantly reducing power penalty. Analysis of the pairwise error probability of the proposed algorithm with a single antenna in each relay is derived and confirmed with numerical results. We show the performance improvements of the precoded scheme, relatively to equivalent distributed SFBC scheme employing 16-QAM, for several channel quality scenarios. Copyright © 2010 Sara Teodoro, et al.European project CODIVPortuguese project CADWINPortuguese project AGILEFC

Novel precoded relay-assisted algorithm for cellular systems

Cooperative schemes are promising solutions for cellular wireless systems to improve system fairness, extend coverage and increase capacity. The use of relays is of significant interest to allow radio access in situations where a direct path is not available or has poor quality. A data precoded relay-assisted scheme is proposed for a system cooperating with 2 relays, each equipped with either a single antenna or 2-antenna array. However, because of the half-duplex constraint at the relays, relaying-assisted transmission would require the use of a higher order constellation than in the case when a continuous link is available from the BS to the UT. This would imply a penalty in the power efficiency. The simple precoding scheme proposed exploits the relation between QPSK and 16-QAM, by alternately transmitting through the 2 relays, achieving full diversity, while significantly reducing power penalty. Analysis of the pairwise error probability of the proposed algorithm with a single antenna in each relay is derived and confirmed with numerical results. We show the performance improvements of the precoded scheme, relatively to equivalent distributed SFBC scheme employing 16-QAM, for several channel quality scenarios. Copyright © 2010 Sara Teodoro, et al.European project CODIVPortuguese project CADWINPortuguese project AGILEFC

Novel precoded relay-assisted algorithm for cellular systems

Cooperative schemes are promising solutions for cellular wireless systems to improve system fairness, extend coverage and increase capacity. The use of relays is of significant interest to allow radio access in situations where a direct path is not available or has poor quality. A data precoded relay-assisted scheme is proposed for a system cooperating with 2 relays, each equipped with either a single antenna or 2-antenna array. However, because of the half-duplex constraint at the relays, relaying-assisted transmission would require the use of a higher order constellation than in the case when a continuous link is available from the BS to the UT. This would imply a penalty in the power efficiency. The simple precoding scheme proposed exploits the relation between QPSK and 16-QAM, by alternately transmitting through the 2 relays, achieving full diversity, while significantly reducing power penalty. Analysis of the pairwise error probability of the proposed algorithm with a single antenna in each relay is derived and confirmed with numerical results. We show the performance improvements of the precoded scheme, relatively to equivalent distributed SFBC scheme employing 16-QAM, for several channel quality scenarios. Copyright © 2010 Sara Teodoro, et al.European project CODIVPortuguese project CADWINPortuguese project AGILEFC

Power allocation strategies for distributed precoded multicell based systems

Multicell cooperation is a promising solution for cellular wireless systems to mitigate intercell interference, improve system fairness, and increase capacity. In this article, we propose power allocation techniques for the downlink of distributed, precoded, multicell cellular-based systems. The precoder is designed in two phases: first the intercell interference is removed by applying a set of distributed precoding vectors; then the system is further optimized through power allocation. Three centralized power allocation algorithms with per-BS power constraint and diferente complexity trade-offs are proposed: one optimal in terms of minimization of the instantaneous average bit error rate (BER), and two suboptimal. In this latter approach, the powers are computed in two phases. First, the powers are derived under total power constraint (TPC) and two criterions are considered, namely, minimization of the instantaneous average BER and minimization of the sum of inverse of signal-to-noise ratio. Then, the final powers are computed to satisfy the individual per-BS power constraint. The performance of the proposed schemes is evaluated, considering typical pedestrian scenarios based on LTE specifications. The numerical results show that the proposed suboptimal schemes achieve a performance very close to the optimal but with lower computational complexity. Moreover, the performance of the proposed per-BS precoding schemes is close to the one obtained considering TPC over a supercell.Portuguese CADWIN - PTDC/ EEA TEL/099241/200