8,844 research outputs found
Degrees of Freedom of Full-Duplex Multiantenna Cellular Networks
We study the degrees of freedom (DoF) of cellular networks in which a full
duplex (FD) base station (BS) equipped with multiple transmit and receive
antennas communicates with multiple mobile users. We consider two different
scenarios. In the first scenario, we study the case when half duplex (HD)
users, partitioned to either the uplink (UL) set or the downlink (DL) set,
simultaneously communicate with the FD BS. In the second scenario, we study the
case when FD users simultaneously communicate UL and DL data with the FD BS.
Unlike conventional HD only systems, inter-user interference (within the cell)
may severely limit the DoF, and must be carefully taken into account. With the
goal of providing theoretical guidelines for designing such FD systems, we
completely characterize the sum DoF of each of the two different FD cellular
networks by developing an achievable scheme and obtaining a matching upper
bound. The key idea of the proposed scheme is to carefully allocate UL and DL
information streams using interference alignment and beamforming techniques. By
comparing the DoFs of the considered FD systems with those of the conventional
HD systems, we establish the DoF gain by enabling FD operation in various
configurations. As a consequence of the result, we show that the DoF can
approach the two-fold gain over the HD systems when the number of users becomes
large enough as compared to the number of antennas at the BS.Comment: 21 pages, 16 figures, a shorter version of this paper has been
submitted to the IEEE International Symposium on Information Theory (ISIT)
201
Bishop-Phelps-Bolloba's theorem on bounded closed convex sets
This paper deals with the \emph{Bishop-Phelps-Bollob\'as property}
(\emph{BPBp} for short) on bounded closed convex subsets of a Banach space ,
not just on its closed unit ball . We firstly prove that the \emph{BPBp}
holds for bounded linear functionals on arbitrary bounded closed convex subsets
of a real Banach space. We show that for all finite dimensional Banach spaces
and the pair has the \emph{BPBp} on every bounded closed convex
subset of , and also that for a Banach space with property
the pair has the \emph{BPBp} on every bounded closed absolutely convex
subset of an arbitrary Banach space . For a bounded closed absorbing
convex subset of with positive modulus convexity we get that the pair
has the \emph{BPBp} on for every Banach space . We further
obtain that for an Asplund space and for a locally compact Hausdorff ,
the pair has the \emph{BPBp} on every bounded closed absolutely
convex subset of . Finally we study the stability of the \emph{BPBp} on
a bounded closed convex set for the -sum or -sum of a
family of Banach spaces
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