Nils Bornhorst

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—In this work, we consider optimal and suboptimal beamforming designs in a multi-operator two-way relaying network with a multiple-input-multiple-output (MIMO) amplify-and-forward (AF) relay. Such a network is interference limited and thus, an interference nulling strategy is reasonable. We first derive the necessary condition for interference nulling and(More)
We generalize the concept of multiuser peer-to-peer (MUP2P) relay networks to that of a multi-group multicasting (MGM) relay network where each source may broadcast its message to a group of multiple users. State-of-the-art beamforming methods, which have been proposed for MUP2P relay networks, are shown to be straightforwardly extendable to such MGM(More)
We consider the problem of transmit beamforming in multi-group multicasting systems with covariance-based channel state information (CSI) available at the transmitter where the total transmitted power is minimized subject to quality-of-service (QoS) constraints at the receivers. Previous approaches for this problem are based on semidefinite relaxation (SDR)(More)
—We consider optimal filter-and-forward (FF) beam-forming (BF) in multiuser peer-to-peer (MUP2P) relay networks with frequency selective fading in which the signals received at a destination are subject to severe inter-symbol interference (ISI) and multiuser interference (MUI). In the FF protocol, the amount of interference not only depends on the choice of(More)
To my father who passed away during my doctoral studies. May he rest in peace. I Acknowledgments First and foremost, I wholeheartedly thank my supervisor Prof. Dr.-Ing. Marius Pe-savento for his support, guidance and the knowledge he has shared with me during my doctoral studies. I also sincerely thank Prof. Alex B. Gershman who started to supervise my(More)
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