Pekka Jänis

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Device-to-Device communication underlaying a cellular network enables local services with limited interference to the cellular network. In this paper we study the optimal selection of possible resource sharing modes with the cellular network in a single cell. Based on the learning from the single cell studies we propose a mode selection procedure for a(More)
In this article we propose to facilitate local peer-to-peer communication by a Device-to-Device (D2D) radio that operates as an underlay network to an IMT-Advanced cellular network. It is expected that local services may utilize mobile peer-to-peer communication instead of central server based communication for rich multimedia services. The main challenge(More)
Future cellular networks such as IMT-Advanced are expected to allow underlaying direct Device-to-Device (D2D) communication for spectrally efficient support of e.g. rich multimedia local services. Enabling D2D links in a cellular network presents a challenge in radio resource management due to the potentially severe interference it may cause to the cellular(More)
In this paper we propose a low complexity frequency-domain method for finding the minimum mean square error (MMSE) equalizer. Special properties of circulant matrices are exploited in the method. Simulations show that only a minor performance loss is experienced compared to time-domain processing. We also compare joint space-time processing to decoupled(More)
We propose a numerical method for finding packings of MIMO semi-unitary precoding matrices in Grassmannian manifolds with different metrics. The proposed expansion– compression algorithm (ECA) is practical, simple and produces efficient packings without the need for a sophisticated initialization. With chordal distance metric, the algorithm tends to(More)
the contributions of their colleagues, although the views expressed are those of the authors and do not necessarily represent the METIS consortium’s view. The consortium is not liable for any use that may be made of any of the information contained therein. Abstract— This paper addresses challenges when designing wireless systems towards the communication(More)
In MIMO systems the interference from the same cell transmit (TX) antennas causes severe interference. Moreover, if the channel is frequency selective, also inter-chip interference is present. Canceling both inter-antenna and inter-chip interference is a challenging task, especially when the same codes are reused across the TX antennas. In this paper we(More)