6,628 research outputs found
Generalized Signal Alignment For MIMO Two-Way X Relay Channels
We study the degrees of freedom (DoF) of MIMO two-way X relay channels.
Previous work studied the case , where and denote the number of
antennas at the relay and each source, respectively, and showed that the
maximum DoF of is achievable when by
applying signal alignment (SA) for network coding and interference cancelation.
This work considers the case where the performance is limited by the
number of antennas at each source node and conventional SA is not feasible. We
propose a \textit{generalized signal alignment} (GSA) based transmission
scheme. The key is to let the signals to be exchanged between every source node
align in a transformed subspace, rather than the direct subspace, at the relay
so as to form network-coded signals. This is realized by jointly designing the
precoding matrices at all source nodes and the processing matrix at the relay.
Moreover, the aligned subspaces are orthogonal to each other. By applying the
GSA, we show that the DoF upper bound is achievable when ( is even) or ( is odd). Numerical results also demonstrate
that our proposed transmission scheme is feasible and effective.Comment: 6 pages, 6 figures, to appear in IEEE ICC 201
and : Candidates for charmed-strange mesons
Newly observed two charmed-strange resonances, and
, are investigated by calculating their Okubo-Zweig-Iizuka
allowed strong decays, which shows that they are suitable candidates for the
and states in the charmed-strange meson family. Our study
also predicts other main decay modes of and ,
which can be accessible at the future experiment. In addition, the decay
behaviors of the spin partners of and , i.e.,
and , are predicted in this work, which are still
missing at present. Experimental search for the missing and
charmed-strange mesons is an intriguing and challenging task
for further experiment.Comment: 8 pages, 3 figures and 4 tables. More discussions added and typos
corrected. Accepted by Eur. Phys. J.
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