10,687 research outputs found
Decomposition by Successive Convex Approximation: A Unifying Approach for Linear Transceiver Design in Heterogeneous Networks
We study the downlink linear precoder design problem in a multi-cell dense
heterogeneous network (HetNet). The problem is formulated as a general
sum-utility maximization (SUM) problem, which includes as special cases many
practical precoder design problems such as multi-cell coordinated linear
precoding, full and partial per-cell coordinated multi-point transmission,
zero-forcing precoding and joint BS clustering and beamforming/precoding. The
SUM problem is difficult due to its non-convexity and the tight coupling of the
users' precoders. In this paper we propose a novel convex approximation
technique to approximate the original problem by a series of convex
subproblems, each of which decomposes across all the cells. The convexity of
the subproblems allows for efficient computation, while their decomposability
leads to distributed implementation. {Our approach hinges upon the
identification of certain key convexity properties of the sum-utility
objective, which allows us to transform the problem into a form that can be
solved using a popular algorithmic framework called BSUM (Block Successive
Upper-Bound Minimization).} Simulation experiments show that the proposed
framework is effective for solving interference management problems in large
HetNet.Comment: Accepted by IEEE Transactions on Wireless Communicatio
Residue cross sections of Ti-induced fusion reactions based on the two-step model
Ti-induced fusion reactions to synthesize superheavy elements are
studied systematically with the two-step model developed recently, where fusion
process is divided into approaching phase and formation phase. Furthermore, the
residue cross sections for different neutron evaporation channels are evaluated
with the statistical evaporation model. In general, the calculated cross
sections are much smaller than that of Ca-induced fusion reactions, but
the results are within the detection capability of experimental facilities
nowadays. The maximum calculated residue cross section for producing superheavy
element is in the reaction Ti+Bk in channels with
pb at = 37.0 MeV.Comment: 6 pages, 7 figure
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