Idle period shortening for TDD communications in large cells,”

Abstract-Time division duplex (TDD) technologies are necessary to deal with unpaired frequency bands and to allow low-complexity user equipments (UE) without duplexer in paired frequency bands. In TDD communications, a frame is divided into several sub-frames, each sub-frame being allocated to either uplink (UL) or downlink (DL). An idle period (IP) is required at a DL/UL switching point. It is usually dimensioned according to the cell radius and is identical for all UEs of the cell. In this paper, we propose a UE-specific IP duration, which increases the overall data rate of TDD communications for large cells. Numerical results show the potentially large benefit of the proposed dimensioning in term of spectral efficiency, which can be obtained without any specific signaling

Soft output detection for multiple antennas : Accelerated sphere decoding and shifted list enumeration

- Nous proposons un détecteur APP de faible complexité capable de démoduler les constellations MAQ émises sur un canal à antennes multiples (jusqu'à 16 antennes). Le détecteur APP recherche le point de vraisemblance maximale (VM) en appliquant un décodage par sphères accéléré. A l'aide d'une énumération de Pohst à double récursion, il construit ensuite une liste centrée sur le point VM afin d'évaluer les probabilités a posteriori. Le rayon de la liste est choisi de façon à stabiliser la taille de la liste et tenir compte des frontières de la constellation finie. En utilisant une modulation MAQ-16 sur un canal symétrique à 4 antennes, un turbo code de rendement 1/2 et des blocs de longueur 20000 bits, nous observons une différence de 1,56 dB seulement entre les performances simulées et la capacité du canal au sens de Shannon

4MORE: An advanced MIMO downlink MC-CDMA system

ABSTRACT The IST 4MORE project defines a multicarrier code division multiple access (MC-CDMA) radio system with multiple mobile users and advances this one step towards implementation through the design of a System on Chip (SoC) for a 4G terminal employing multiple antennas, based on MC-CDMA. In this contribution we present results of the simulated downlink scenario, which is the base for the designed demonstrator. We cover different channels, various modulation schemes, coarse time synchronization, carrier frequency offset tracking and finally the effect and countermeasures which are needed for RF impairments. The implemented air interface offers transmitting 5.5 bits/s/Hz over two spatial parallel multiplexed data streams

Association of the PHACTR1/EDN1 genetic locus with spontaneous coronary artery dissection

Background: Spontaneous coronary artery dissection (SCAD) is an increasingly recognized cause of acute coronary syndromes (ACS) afflicting predominantly younger to middle-aged women. Observational studies have reported a high prevalence of extracoronary vascular anomalies, especially fibromuscular dysplasia (FMD) and a low prevalence of coincidental cases of atherosclerosis. PHACTR1/EDN1 is a genetic risk locus for several vascular diseases, including FMD and coronary artery disease, with the putative causal noncoding variant at the rs9349379 locus acting as a potential enhancer for the endothelin-1 (EDN1) gene. Objectives: This study sought to test the association between the rs9349379 genotype and SCAD. Methods: Results from case control studies from France, United Kingdom, United States, and Australia were analyzed to test the association with SCAD risk, including age at first event, pregnancy-associated SCAD (P-SCAD), and recurrent SCAD. Results: The previously reported risk allele for FMD (rs9349379-A) was associated with a higher risk of SCAD in all studies. In a meta-analysis of 1,055 SCAD patients and 7,190 controls, the odds ratio (OR) was 1.67 (95% confidence interval [CI]: 1.50 to 1.86) per copy of rs9349379-A. In a subset of 491 SCAD patients, the OR estimate was found to be higher for the association with SCAD in patients without FMD (OR: 1.89; 95% CI: 1.53 to 2.33) than in SCAD cases with FMD (OR: 1.60; 95% CI: 1.28 to 1.99). There was no effect of genotype on age at first event, P-SCAD, or recurrence. Conclusions: The first genetic risk factor for SCAD was identified in the largest study conducted to date for this condition. This genetic link may contribute to the clinical overlap between SCAD and FMD

Iterative interference cancellation scheme with pilot-aided spacetime estimation in ds-cdma systems

Abstract: Iterative multiuser interference cancellation schemes for Direct Sequence Code Division Multiple Access systems exhibit good performance results for a reasonable complexity. We study an efficient iterative scheme, combining interference cancellation, soft input soft output decoding and beamforming. To deal with unknown channels, we add a pilot-aided space-time channel estimation in each iteration. The iterative structure has two advantages: the observation signal used for estimation contains less interference from one iteration to the following and soft estimates of coded bits are available for data-aided estimation