Ralf R. Müller

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We consider a canonical model for coded code-division multiple access (CDMA) with random spreading, where the receiver makes use of iterative belief-propagation (BP) joint decoding. We provide simple density-evolution analysis in the large-system limit (large number of users) of the performance of the BP decoder and of some suboptimal approximations based(More)
A random matrix model is introduced that probabilistically describes the spatial and temporal multi–path propagation between a transmitting and receiving antenna array with a limited number of scatterers for mobile radio and indoor environments. The model characterizes the channel by its richness delay profile which gives the number of scattering objects as(More)
A subspace projection to improve channel estimation in massive multi-antenna systems is proposed and analyzed. Together with power-controlled hand-off, it can mitigate the pilot contamination problem without the need for coordination among cells. The proposed method is blind in the sense that it does not require pilot data to find the appropriate subspace.(More)
We consider a wireless communication system formed by a single cell with one base station and K user terminals. User channels are characterized by frequency-selective fading due to small-scale effects, modeled as a set of M parallel block-fading channels, and a frequency-flat distance-dependent path loss. We compare delay-limited systems with variable-rate(More)
In Arabidopsis thaliana, the stem cell population of the shoot system is controlled by regulatory circuitry involving the WUSCHEL (WUS) and CLAVATA (CLV1-3) genes. WUS signals from the organizing center (OC) to promote stem cell fate at the meristem apex. Stem cells express the secreted peptide CLV3 that activates a signal transduction cascade to restrict(More)
Continuous growth and development of plants is controlled by meristems that harbour stem cell pools. Division of stem cells and differentiation of their progeny are coordinated by intercellular signaling. In Arabidopsis, stem cells in shoot and floral meristems secrete CLAVATA3, a member of the CLE protein family that activates the CLV1/CLV2 receptor(More)
There is a paucity of large-scale field investigations on the effects of organic toxicants on stream macroinvertebrate community structure and ecosystem functions. We investigated a total of 29 streams in two study areas of France and Finland for pesticide exposure, invertebrates and leaf-litter breakdown. To link pesticide exposure and community(More)
We devise theoretical grounds for constructing channel models for multiple-input multiple-output (MIMO) systems based on information-theoretic tools. The paper provides a general method to derive a channel model which is consistent with one's state of knowledge. The framework we give here has already been fruitfully explored with success in the context of(More)
Linear multiuser detectors for vector channels with crosstalk are approximated by weighted matrix polynomials. The weight optimization problem is overcome using convergence results from random matrix theory. The results are also extended to receivers with subsequent successive decoding. In the case of subsequent successive decoding, a novel low-complexity(More)
The linear vector-valued channel + with and denoting additive white Gaussian noise and independent random matrices, respectively, is analyzed in the asymptotic regime as the dimensions of the matrices and vectors involved become large. The asymptotic eigenvalue distribution of the channel’s covariance matrix is given in terms of an implicit equation for its(More)