15,102 research outputs found
Millimeter-wave Evolution for 5G Cellular Networks
Triggered by the explosion of mobile traffic, 5G (5th Generation) cellular
network requires evolution to increase the system rate 1000 times higher than
the current systems in 10 years. Motivated by this common problem, there are
several studies to integrate mm-wave access into current cellular networks as
multi-band heterogeneous networks to exploit the ultra-wideband aspect of the
mm-wave band. The authors of this paper have proposed comprehensive
architecture of cellular networks with mm-wave access, where mm-wave small cell
basestations and a conventional macro basestation are connected to
Centralized-RAN (C-RAN) to effectively operate the system by enabling power
efficient seamless handover as well as centralized resource control including
dynamic cell structuring to match the limited coverage of mm-wave access with
high traffic user locations via user-plane/control-plane splitting. In this
paper, to prove the effectiveness of the proposed 5G cellular networks with
mm-wave access, system level simulation is conducted by introducing an expected
future traffic model, a measurement based mm-wave propagation model, and a
centralized cell association algorithm by exploiting the C-RAN architecture.
The numerical results show the effectiveness of the proposed network to realize
1000 times higher system rate than the current network in 10 years which is not
achieved by the small cells using commonly considered 3.5 GHz band.
Furthermore, the paper also gives latest status of mm-wave devices and
regulations to show the feasibility of using mm-wave in the 5G systems.Comment: 17 pages, 12 figures, accepted to be published in IEICE Transactions
on Communications. (Mar. 2015
Optimal Deterministic Polynomial-Time Data Exchange for Omniscience
We study the problem of constructing a deterministic polynomial time
algorithm that achieves omniscience, in a rate-optimal manner, among a set of
users that are interested in a common file but each has only partial knowledge
about it as side-information. Assuming that the collective information among
all the users is sufficient to allow the reconstruction of the entire file, the
goal is to minimize the (possibly weighted) amount of bits that these users
need to exchange over a noiseless public channel in order for all of them to
learn the entire file. Using established connections to the multi-terminal
secrecy problem, our algorithm also implies a polynomial-time method for
constructing a maximum size secret shared key in the presence of an
eavesdropper. We consider the following types of side-information settings: (i)
side information in the form of uncoded fragments/packets of the file, where
the users' side-information consists of subsets of the file; (ii) side
information in the form of linearly correlated packets, where the users have
access to linear combinations of the file packets; and (iii) the general
setting where the the users' side-information has an arbitrary (i.i.d.)
correlation structure. Building on results from combinatorial optimization, we
provide a polynomial-time algorithm (in the number of users) that, first finds
the optimal rate allocations among these users, then determines an explicit
transmission scheme (i.e., a description of which user should transmit what
information) for cases (i) and (ii)
Data Exchange Problem with Helpers
In this paper we construct a deterministic polynomial time algorithm for the
problem where a set of users is interested in gaining access to a common file,
but where each has only partial knowledge of the file. We further assume the
existence of another set of terminals in the system, called helpers, who are
not interested in the common file, but who are willing to help the users. Given
that the collective information of all the terminals is sufficient to allow
recovery of the entire file, the goal is to minimize the (weighted) sum of bits
that these terminals need to exchange over a noiseless public channel in order
achieve this goal. Based on established connections to the multi-terminal
secrecy problem, our algorithm also implies a polynomial-time method for
constructing the largest shared secret key in the presence of an eavesdropper.
We consider the following side-information settings: (i) side-information in
the form of uncoded packets of the file, where the terminals' side-information
consists of subsets of the file; (ii) side-information in the form of linearly
correlated packets, where the terminals have access to linear combinations of
the file packets; and (iii) the general setting where the the terminals'
side-information has an arbitrary (i.i.d.) correlation structure. We provide a
polynomial-time algorithm (in the number of terminals) that finds the optimal
rate allocations for these terminals, and then determines an explicit optimal
transmission scheme for cases (i) and (ii)
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Versatile stochastic dot product circuits based on nonvolatile memories for high performance neurocomputing and neurooptimization.
The key operation in stochastic neural networks, which have become the state-of-the-art approach for solving problems in machine learning, information theory, and statistics, is a stochastic dot-product. While there have been many demonstrations of dot-product circuits and, separately, of stochastic neurons, the efficient hardware implementation combining both functionalities is still missing. Here we report compact, fast, energy-efficient, and scalable stochastic dot-product circuits based on either passively integrated metal-oxide memristors or embedded floating-gate memories. The circuit's high performance is due to mixed-signal implementation, while the efficient stochastic operation is achieved by utilizing circuit's noise, intrinsic and/or extrinsic to the memory cell array. The dynamic scaling of weights, enabled by analog memory devices, allows for efficient realization of different annealing approaches to improve functionality. The proposed approach is experimentally verified for two representative applications, namely by implementing neural network for solving a four-node graph-partitioning problem, and a Boltzmann machine with 10-input and 8-hidden neurons
Engineering orthogonal dual transcription factors for multi-input synthetic promoters
Synthetic biology has seen an explosive growth in the capability of engineering artificial gene circuits from transcription factors (TFs), particularly in bacteria. However, most artificial networks still employ the same core set of TFs (for example LacI, TetR and cI). The TFs mostly function via repression and it is difficult to integrate multiple inputs in promoter logic. Here we present to our knowledge the first set of dual activator-repressor switches for orthogonal logic gates, based on bacteriophage λ cI variants and multi-input promoter architectures. Our toolkit contains 12 TFs, flexibly operating as activators, repressors, dual activator–repressors or dual repressor–repressors, on up to 270 synthetic promoters. To engineer non cross-reacting cI variants, we design a new M13 phagemid-based system for the directed evolution of biomolecules. Because cI is used in so many synthetic biology projects, the new set of variants will easily slot into the existing projects of other groups, greatly expanding current engineering capacities
The rational development of molecularly imprinted polymer-based sensors for protein detection.
The detection of specific proteins as biomarkers of disease, health status,
environmental monitoring, food quality, control of fermenters and civil defence
purposes means that biosensors for these targets will become increasingly more
important. Among the technologies used for building specific recognition
properties, molecularly imprinted polymers (MIPs) are attracting much attention.
In this critical review we describe many methods used for imprinting recognition
for protein targets in polymers and their incorporation with a number of
transducer platforms with the aim of identifying the most promising approaches
for the preparation of MIP-based protein sensors (277 references)
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