With the introduction of orthogonal frequency- division multiplexing and multiple antennas in cellular networks, there are new opportunities to adapt the transmission to propagation and interference conditions. In this article we describe a practical approach using space-frequency-selective multiuser MIMO scheduling. Frequency-selective feedback is provided on achievable data rates for preferred single- and multistream transmission modes. The base station selects the best mode while providing instantaneous fairness. We observe that multiuser transmission increases the probability of using multistream transmission. Besides the benefits from optimal combining at the physical layer, there is an additional gain at the MAC layer since the estimation of achievable rates becomes more precise. Altogether, 93 percent of the theoretical throughput can be realized by synchronizing the base stations and providing cell-specific reference signals. We have implemented essential functions of the approach in real time on an experimental 3GPP LTE prototype in 20 MHz bandwidth. Feasibility of the key features is proven in laboratory and field trials

Es wurde ein Verfahren zur kontinuierlichen u-Sulfonierung \on Estern gesattigter Fettsauren mit SO, ausgearbeitet und ein spezielles Bleichverfahren fur diese Produkte entwickelt. Der Umsatz, also der Sulfoniergrad, liegt bei 95-99 o/o. Losungsmittel, weitere Verarbeitungsstufen oder Reinigungsoperationen zur Abtrennung von Nebenprodukten sind nicht erforderlich. Preparation of Esters of a-Sulfo-Fatty AcidsA process for the continuous a-sulfonation of saturated fatty acid esters with SO, was worked out and a special bleaching process was developed for these products. The conversion, i. e. the degree of sulfonation is of the order of 95-99"/0. Solvents, further processing steps or purification operations for the separation of by-products are not required.

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In multiuser multiple-input multiple-output (MIMO) systems the performance of joint detection and joint predistortion techniques highly depends on the quality of radio-frequency (RF) components. Therefore, the focus of this paper is on front-end imperfections. We demonstrate the influence of erroneous calibration (which is essential for downlink predistortion), phase noise and nonlinear amplifiers. For all issues we elaborate on the different disturbances that arise, analyse the impact on symbol estimation and evaluate system performance in terms of coded bit error ratio (BER). A general result for all examined front-end imperfections is that their influence increases with the number of spatially multiplexed data streams culminating in unacceptable performance degradation in fully loaded systems. Moreover, Wiener-based detection and predistortion reduces the degradation due to front-end imperfections in low SNR regimes compared to zero forcing