Alcatel-Lucent

About: Alcatel-Lucent is a based out in Stuttgart, Germany. It is known for research contribution in the topics: Signal & Network packet. The organization has 37003 authors who have published 53332 publications receiving 1430547 citations. The organization is also known as: Alcatel-Lucent S.A. & Alcatel.

Optimum routing system

Abstract: A wireless data network includes a wireless packet switched data network for end users that divides mobility management into local, micro, macro and global connection handover categories and minimizes handoff updates according to the handover category. The network integrates MAC handoff messages with network handoff messages. The network separately directs registration functions to a registration server and direct routing functions to inter-working function units. The network provides an intermediate XTunnel channel between a wireless hub (also called access hub AH) and an inter-working function unit (IWF unit) in a foreign network, and it provides an IXTunnel channel between an inter-working function unit in a foreign network and an inter-working function unit in a home network. The network enhances the layer two tunneling protocol (L2TP) to support a mobile end system, and it performs network layer registration before the start of a PPP communication session.

An approach to probe some neural systems interaction by functional MRI at neural time scale down to milliseconds

Abstract: In this paper, we demonstrate an approach by which some evoked neuronal events can be probed by functional MRI (fMRI) signal with temporal resolution at the time scale of tens of milliseconds. The approach is based on the close relationship between neuronal electrical events and fMRI signal that is experimentally demonstrated in concurrent fMRI and electroencephalographic (EEG) studies conducted in a rat model with forepaw electrical stimulation. We observed a refractory period of neuronal origin in a two-stimuli paradigm: the first stimulation pulse suppressed the evoked activity in both EEG and fMRI signal responding to the subsequent stimulus for a period of several hundred milliseconds. When there was an apparent site-site interaction detected in the evoked EEG signal induced by two stimuli that were primarily targeted to activate two different sites in the brain, fMRI also displayed signal amplitude modulation because of the interactive event. With visual stimulation using two short pulses in the human brain, a similar refractory phenomenon was observed in activated fMRI signals in the primary visual cortex. In addition, for interstimulus intervals shorter than the known latency time of the evoked potential induced by the first stimulus ( approximately 100 ms) in the primary visual cortex of the human brain, the suppression was not present. Thus, by controlling the temporal relation of input tasks, it is possible to study temporal evolution of certain neural events at the time scale of their evoked electrical activity by noninvasive fMRI methodology.

Polarized MIMO channels in 3-D: models, measurements and mutual information

Abstract: Fourth-generation (4G) systems are expected to support data rates of the order of 100 Mb/s in the outdoor environment and 1 Gb/s in the indoor/stationary environment. In order to support such large payloads, the radio physical layer must employ receiver algorithms that provide a significant increase in spectrum efficiency (and, hence, capacity) over current wireless systems. Recently, an explosion of multiple-input-multiple-output (MIMO) studies have appeared with many journals presenting special issues on this subject. This has occurred due to the potential of MIMO to provide a linear increase in capacity with antenna numbers. Environmental considerations and tower loads will often restrict the placing of large antenna spans on base stations (BSs). Similarly, customer device form factors also place a limit on the antenna numbers that can be placed with a mutual spacing of 0.5 wavelength. The use of cross-polarized antennas is widely used in modern cellular installations as it reduces spacing needs and tower loads on BSs. Hence, this approach is also receiving considerable attention in MIMO systems. In order to study and compare various receiver architectures that are based on MIMO techniques, one needs to have an accurate knowledge of the MIMO channel. However, very few studies have appeared that characterize the cross-polarized MIMO channel. Recently, the third-generation partnership standards bodies (3GPP/3GPP2) have defined a cross-polarized channel model for MIMO systems but this model neglects the elevation spectrum. In this paper, we provide a deeper understanding of the channel model for cross-polarized systems for different environments and propose a composite channel impulse model for the cross-polarized channel that takes into account both azimuth and elevation spectrum. We use the resulting channel impulse response to derive closed-form expressions for the spatial correlation. We also present models to describe the dependence of cross-polarization discrimination (XPD) on distance, azimuth and elevation and delay spread. In addition, we study the impact of array width, signal-to-noise ratio, and antenna slant angle on the mutual information (MI) of the system. In particular, we present an analytical model for large system mean mutual information values and consider the impact of elevation spectrum on MI. Finally, the impact of multipath delays on XPD and MI is also explored.

Network MIMO: Overcoming Intercell Interference in Indoor Wireless Systems

Abstract: Network MIMO is a family of techniques whereby each user in a wireless system is served through all the access points within its range of influence By tightly coordinating the transmission and reception of signals at multiple access points, network MIMO transcends the limits on spectral efficiency due to intercell interference Taking prior information- theoretic analyses of Network MIMO to the next level, this paper quantifies the spectral efficiency gains obtainable under realistic propagation and operational conditions Our study relies on detailed simulations and, for specificity, is conducted within the framework of the IEEE 80216e Mobile WiMAX system All the relevant physical-layer functionalities of Mobile WiMAX are accurately replicated Furthermore, to facilitate the coordination between access points, we postulate an indoor deployment organized around a gigabit-ethernet backhaul The results confirm that Network MIMO stands to provide a multiple-fold increase in spectral efficiency under such conditions

Fibre-optical features of a glass sponge

Abstract: Some superior technological secrets have come to light from a deep-sea organism. Modern technology cannot yet compete with some of the sophisticated optical systems possessed by biological organisms1,2,3. Here we show that the spicules of the deep-sea 'glass' sponge Euplectella have remarkable fibre-optical properties, which are surprisingly similar to those of commercial telecommunication fibres — except that the spicules themselves are formed under normal ambient conditions and have some technological advantages over man-made versions.