3,774 research outputs found
Capacity Bounds for Two-Hop Interference Networks
This paper considers a two-hop interference network, where two users transmit
independent messages to their respective receivers with the help of two relay
nodes. The transmitters do not have direct links to the receivers; instead, two
relay nodes serve as intermediaries between the transmitters and receivers.
Each hop, one from the transmitters to the relays and the other from the relays
to the receivers, is modeled as a Gaussian interference channel, thus the
network is essentially a cascade of two interference channels. For this
network, achievable symmetric rates for different parameter regimes under
decode-and- forward relaying and amplify-and-forward relaying are proposed and
the corresponding coding schemes are carefully studied. Numerical results are
also provided.Comment: 8 pages, 5 figures, presented in Allerton Conference'0
Bose-Einstein Condensate in a Honeycomb Optical Lattice: Fingerprint of Superfluidity at the Dirac Point
Mean-field Bloch bands of a Bose-Einstein condensate in a honeycomb optical
lattice are computed. We find that the topological structure of the Bloch bands
at the Dirac point is changed completely by the atomic interaction of arbitrary
small strength: the Dirac point is extended into a closed curve and an
intersecting tube structure arises around the original Dirac point. These tubed
Bloch bands are caused by the superfluidity of the system. Furthermore, they
imply the inadequacy of the tight-binding model to describe an interacting
Boson system around the Dirac point and the breakdown of adiabaticity by
interaction of arbitrary small strength
- …