1,833 research outputs found

    Pilot-aided ML schemes for joint beamforming and channel estimation in WCDMA systems

    Get PDF
    This paper proposes semi-blind channel estimation and interference cancellation schemes for the reception of pilot-aided signals in WCDMA systems. It is shown that the performance of classical training-based schemes is severely degraded due to the code-multiplexing (as opposed to time-multiplexing) of traffic and pilot signals. The time-dispersivity of the channel destroys the orthogonality between the traffic signal and the pilot, and consequently the traffic signal appears as a new interfering signal for the channel estimation/beamforming algorithm. In order to avoid this effect, we propose techniques that exploit both the presence of the training sequence and the structure of the traffic signal in a semi-blind fashion.Peer ReviewedPostprint (published version

    Canonical Noether symmetries and commutativity properties for gauge systems

    Get PDF
    For a dynamical system defined by a singular Lagrangian, canonical Noether symmetries are characterized in terms of their commutation relations with the evolution operators of Lagrangian and Hamiltonian formalisms. Separate characterizations are given in phase space, in velocity space, and through an evolution operator that links both spaces.Comment: 22 pages; some references updated, an uncited reference deleted, minor style change

    In memoriam Josep Maria Palau i Camps (1914-1996)

    Get PDF
    Abstract not availabl

    Noves dades sobre bioespeleologia de Sardenya (Arachnida, Araneae)

    Get PDF

    La fauna endèmica Iberobalear i la seva conservació

    Get PDF
    Ibero-balearic endemic fauna and its conservation. The Iberian peninsula and the Balearic Islands constitute two outstanding territories in terms of animal biodiversity and endemic species. The continental freshwater fish, the reptiles and amphibians, and to a lesser extent birds, make up the groups of most unique vertebrates and those most renowned as threatened species. The biodiversity of Iberian invertebrates seems very high, but huge research efforts and accurate studies are necessary before their diversity can be quantified

    High resolution probe of coherence in low-energy charge exchange collisions with oriented targets

    Get PDF
    The trapping lasers of a magneto-optical trap (MOT) are used to bring Rb atoms into well defined oriented states. Coupled to recoil-ion momentum spectroscopy (RIMS), this yields a unique MOTRIMS setup which is able to probe scattering dynamics, including their coherence features, with unprecedented resolution. This technique is applied to the low-energy charge exchange processes Na+^++Rb(5p±15p_{\pm 1}) →\rightarrow Na(3p,4s3p,4s)+Rb+^+. The measurements reveal detailed features of the collisional interaction which are employed to improve the theoretical description. All of this enables to gauge the reliability of intuitive pictures predicting the most likely capture transitions
    • …
    corecore