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.

Maximum likelihood decoding in a space division multiplexing system

Abstract: An analysis is made of maximum likelihood decoding (MLD) in a wireless space division multiplexing (SDM) link, where information is transmitted and received simultaneously over several transmit and receive antennas to achieve large data rates and high spectral efficiencies. It is proven that maximum likelihood decoding obtains a diversity order equal to the number of receive antennas, independent of the number of the transmit antennas, while conventional processing techniques such as the minimum mean square error (MMSE) technique obtain a diversity order equal to the number of receive antennas minus the number of transmit antennas plus one. Hence, compared to conventional techniques, maximum likelihood decoding has a significant signal-to-noise ratio advantage which grows with the number of transmit antennas. Maximum likelihood decoding even works when the number of transmit antennas is larger than the number of receive antennas, which is not possible for conventional techniques.

Strongly Anisotropic Transport in Higher Two-Dimensional Landau Levels

Abstract: Low-temperature, electronic transport in Landau levels N>1 of a two-dimensional electron system is strongly anisotropic. At half-filling of either spin level of each such Landau level the magnetoresistance either collapses to form a deep minimum or is peaked in a sharp maximum, depending on the in-plane current direction. Such anisotropies are absent in the N=0 and N=1 Landau level, which are dominated by the states of the fractional quantum Hall effect. The transport anisotropies may be indicative of a new many particle state, which forms exclusively in higher Landau levels.

A beam tracing method for interactive architectural acoustics

Abstract: A difficult challenge in geometrical acoustic modeling is computing propagation paths from sound sources to receivers fast enough for interactive applications. This paper describes a beam tracing method that enables interactive updates of propagation paths from a stationary source to a moving receiver in large building interiors. During a precomputation phase, convex polyhedral beams traced from the location of each sound source are stored in a “beam tree” representing the regions of space reachable by potential sequences of transmissions, diffractions, and specular reflections at surfaces of a 3D polygonal model. Then, during an interactive phase, the precomputed beam tree(s) are used to generate propagation paths from the source(s) to any receiver location at interactive rates. The key features of this beam tracing method are (1) it scales to support large building environments, (2) it models propagation due to edge diffraction, (3) it finds all propagation paths up to a given termination criterion without exhaustive search or risk of under-sampling, and (4) it updates propagation paths at interactive rates. The method has been demonstrated to work effectively in interactive acoustic design and virtual walkthrough applications.

Insights into PPLive: A Measurement Study of a Large-Scale P2P IPTV System

Abstract: With over 100,000 simultaneous users (typically), PPLive is the most popular IPTV application today. PPLive uses a peer-to-peer design, in which peers download and redistribute live television content from and to other peers. Although PPLive is paving the way for an important new class of bandwidth intensive applica- tions, little is known about it due to the proprietary nature of its protocol. In this paper we undertake a preliminary measurement study of PPLive, reporting results from passive packet sniffing of residential and campus peers. We report results for streaming per- formance, workload characteristics, and overlay properties.

Time-delay estimation via linear interpolation and cross correlation

Abstract: Time-delay estimation (TDE), which aims at measuring the relative time difference of arrival (TDOA) between different channels is a fundamental approach for identifying, localizing, and tracking radiating sources Recently, there has been a growing interest in the use of TDE based locator for applications such as automatic camera steering in a room conferencing environment where microphone sensors receive not only the direct-path signal, but also attenuated and delayed replicas of the source signal due to reflections from boundaries and objects in the room This multipath propagation effect introduces echoes and spectral distortions into the observation signal, termed as reverberation, which severely deteriorates a TDE algorithm in its performance This paper deals with the TDE problem with emphasis on combating reverberation using multiple microphone sensors The multichannel cross correlation coefficient (MCCC) is rederived here, in a new way, to connect it to the well-known linear interpolation technique Some interesting properties and bounds of the MCCC are discussed and a recursive algorithm is introduced so that the MCCC can be estimated and updated efficiently when new data snapshots are available We then apply the MCCC to the TDE problem The resulting new algorithm can be treated as a natural generalization of the generalized cross correlation (GCC) TDE method to the multichannel case It is shown that this new algorithm can take advantage of the redundancy provided by multiple microphone sensors to improve TDE against both reverberation and noise Experiments confirm that the relative time-delay estimation accuracy increases with the number of sensors