On Channel Inseparability and the DoF Region of MIMO Multi-way Relay Channels

Conference: SCC 2015 - 10th International ITG Conference on Systems, Communications and Coding
02/02/2015 - 02/05/2015 at Hamburg, Germany

Proceedings: ITG-Fb 254: 10th International ITG Conference on Systems, Communications and Coding (SCC 2015)

Pages: 6Language: englishTyp: PDF

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Chaaban, Anas; Sezgin, Aydin (Institute of Digital Communication Systems, Ruhr-Universit├Ąt Bochum (RUB), Germany)

Full-duplex multi-way relaying is a potential solution for supporting high data rates in future Internet-of-Things (IoT) and 5G networks. Thus, in this paper the full-duplex MIMO multi-way channel consisting of 3 users (Y-channel) with M antennas each and a common relay node with N antennas is studied. Each user wants to exchange messages with all the other users via the relay. A transmission strategy is proposed based on channel diagonalization that decomposes the channel into parallel sub-channels, and physical-layer network coding over these subchannels. It is shown that the proposed strategy achieves the optimal DoF region of the channel if N = M. Furthermore, the proposed strategy that requires joint encoding over multiple sub-channels is compared to another strategy that encodes over each sub-channel separately. It turns out that coding jointly over sub-channels is necessary for an optimal transmission strategy. This shows that the MIMO Y-channel is inseparable.