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Die Trichterbrust (Pectus excavatum, PE) ist eine der häufigsten angeborenen Fehlbildungen. Sie ist gekennzeichnet durch eine Einsenkung des Sternums, wofür das abnormale Wachstum des chondrokostalen Rippenknorpels als Ursache postuliert wird. Die PE kann oft zu einer pathologischen Körperhaltung (Kyphose, Skoliose) führen. Sind die Beschwerden im Kleinkindalter noch eher gering, können sich im Adoleszentenalter...
In this paper we compare general unitary beamforming to constant modulus unitary beamforming in terms of achievable sum-rate for MIMO broadcast channels. We give a complete analysis of both schemes in the 2 × 2 multi-user MISO configuration. Furthermore, we study the regime of asymptotically high signal-to-noise ratio. For growing number of transmit antennas the sum-rate gap between both schemes is...
In this paper we analyse unitary beamforming in MIMO broadcast channels where the entries of the beamforming matrix are of constant modulus (CUBF). We provide a general formal description for the beamforming matrices. We show that this description encompasses currently applied constructions such as those based on the Householder transformation. Among other properties the CUBF proves to be particularly...
We consider some known techniques for transmitting an analog source under the quadratic distortion criterion over a slowly-varying fading AWGN channel. We examine the case where the source is actually compressed, i.e., the source bandwidth is larger than the channel bandwidth. This makes the problem non-trivial. We optimize progressive transmission, superposition coding and an analog-digital hybrid...
This paper presents the scalability of H-ARQ systems in wireless multicast networks. We consider a wireless downlink scenario with one transmitter (base-station) that has to reliably deliver the same information to several receivers (user terminals). The channel is block-fading Gaussian. Since the users are completely symmetric and information is the same for all, the optimal delay-unconstrained coding...
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