We consider the channel assignment problem in a multi-radio wireless mesh network that involves assigning channels to radio interfaces for achieving efficient channel utilization. We present a graph-theoretic formulation of the channel assignment guided by a novel topology control perspective, and show that the resulting optimization problem is NP-complete. We also present an ILP formulation that is used for obtaining a lower bound for the optimum.We then develop a new greedy heuristic channel assignment algorithm (termed CLICA) for finding connected, low interference topologies by utilizing multiple channels. Our evaluations show that the proposed CLICA algorithm exhibits similar behavior and comparable performance relative to the optimum bound with respect to interference and capacity measures. Moreover, our extensive simulation studies show that it can provide a large reduction in interference even with a small number of radios per node, which in turn leads to significant gains in both link layer and multihop performance in 802.11-based multi-radio mesh networks.
Optoelectrically functional 3D ZnO nanomeshes are synthesized via vapor-phase material infiltration into hierarchically self-assembled block copolymer thin films.
Organic–inorganic hybrids featuring tunable material
properties can be readily generated by applying vapor- or liquid-phase
infiltration (VPI or LPI) of inorganic materials into organic templates,
with resulting properties controlled by type and quantity of infiltrated
inorganics. While LPI offers more diverse choices of infiltratable
elements, it tends to yield smaller infiltration amount than VPI,
but the attempt to address the issue has been rarely reported. Here,
we demonstrate a facile temperature-enhanced LPI method to control
and drastically increase the quantity and kinetics of Pt infiltration
into self-assembled polystyrene-block-poly(2-vinylpyridine)
block copolymer (BCP) thin films. By applying LPI at mildly elevated
temperatures (40–80 °C), we showcase controllable optical
functionality of hybrid BCP films along with conductive three-dimensional
(3D) inorganic nanostructures. Structural analysis reveals enhanced
metal loading into the BCP matrix at higher LPI temperatures, suggesting
multiple metal ion infiltration per monomer of P2VP. Combining temperature-enhanced
LPI with hierarchical multilayer BCP self-assembly, we generate BCP-metal
hybrid optical coatings featuring tunable antireflective properties
as well as scalable conductive 3D Pt nanomesh structures. Enhanced
material infiltration and control by temperature-enhanced LPI not
only enables tunability of organic–inorganic hybrid nanostructures
and properties but also expands the application of BCPs for generating
uniquely functional inorganic nanostructures.
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