Nils Bornhorst

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We generalize the concept of multiuser peer-to-peer (MUP2P) relay networks, where <i>K</i> source-destination pairs communicate through <i>L</i> relays, to that of a multi-group multicasting (MGM) relay network. In the MGM scenario, each source may broadcast its message to a group of multiple users rather than to a single user only. Common distributed(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 propose a novel algorithm for transmit beamforming to multiple cochannel multicast groups. The problem of minimizing the total power transmitted by the antenna array subject to quality-of-service (QoS) constraints at the receivers is considered. We show that this problem, which is known to be NP-hard, can be approximated by a second-order cone(More)
We address the problem of transmit beamforming to multiple cochannel multicast groups where the total transmitted power is minimized subject to quality-of-service (QoS) constraints at the receivers. The iterative second-order cone programming (SOCP) approach recently proposed in [2] is a powerful tool to solve this problem and has certain advantages over(More)
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) amplifyand-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 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) beamforming (BF) in multi-user 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 multi-user interference (MUI). In the FF protocol, the amount of interference not only depends on the choice of(More)
In multi-user (MU) downlink beamforming, a high spectral efficiency along with a low transmit power is achieved by separating multiple users in space rather than in time or frequency using spatially selective transmit beams. For streaming media applications, multi-group multicast (MGM) downlink beamforming is a promising approach to exploit the broadcasting(More)
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