6,203 research outputs found
Joint Power Control and Fronthaul Rate Allocation for Throughput Maximization in OFDMA-based Cloud Radio Access Network
The performance of cloud radio access network (C-RAN) is constrained by the
limited fronthaul link capacity under future heavy data traffic. To tackle this
problem, extensive efforts have been devoted to design efficient signal
quantization/compression techniques in the fronthaul to maximize the network
throughput. However, most of the previous results are based on
information-theoretical quantization methods, which are hard to implement due
to the extremely high complexity. In this paper, we consider using practical
uniform scalar quantization in the uplink communication of an orthogonal
frequency division multiple access (OFDMA) based C-RAN system, where the mobile
users are assigned with orthogonal sub-carriers for multiple access. In
particular, we consider joint wireless power control and fronthaul quantization
design over the sub-carriers to maximize the system end-to-end throughput.
Efficient algorithms are proposed to solve the joint optimization problem when
either information-theoretical or practical fronthaul quantization method is
applied. Interestingly, we find that the fronthaul capacity constraints have
significant impact to the optimal wireless power control policy. As a result,
the joint optimization shows significant performance gain compared with either
optimizing wireless power control or fronthaul quantization alone. Besides, we
also show that the proposed simple uniform quantization scheme performs very
close to the throughput performance upper bound, and in fact overlaps with the
upper bound when the fronthaul capacity is sufficiently large. Overall, our
results would help reveal practically achievable throughput performance of
C-RAN, and lead to more efficient deployment of C-RAN in the next-generation
wireless communication systems.Comment: submitted for possible publicatio
Joint Source-Channel Coding of JPEG 2000 Image Transmission Over Two-Way Multi-Relay Networks
In this paper, we develop a two-way multi-relay scheme for JPEG 2000 image transmission. We adopt a modified time-division broadcast (TDBC) cooperative protocol, and derive its power allocation and relay selection under a fairness constraint. The symbol error probability of the optimal system configuration is then derived. After that, a joint source-channel coding (JSCC) problem is formulated to find the optimal number of JPEG 2000 quality layers for the image and the number of channel coding packets for each JPEG 2000 codeblock that can minimize the reconstructed image distortion for the two users, subject to a rate constraint. Two fast algorithms based on dynamic programming (DP) and branch and bound (BB) are then developed. Simulation demonstrates that the proposed JSCC scheme achieves better performance and lower complexity than other similar transmission systems
GreatSplicing: A Semantically Rich Splicing Dataset
In existing splicing forgery datasets, the insufficient semantic varieties of
spliced regions cause a problem that trained detection models overfit semantic
features rather than splicing traces. Meanwhile, because of the absence of a
reasonable dataset, different detection methods proposed cannot reach a
consensus on experimental settings. To address these urgent issues,
GreatSplicing, a manually created splicing dataset with a considerable amount
and high quality, is proposed in this paper. GreatSplicing comprises 5,000
spliced images and covers spliced regions with 335 distinct semantic
categories, allowing neural networks to grasp splicing traces better. Extensive
experiments demonstrate that models trained on GreatSplicing exhibit minimal
misidentification rates and superior cross-dataset detection capabilities
compared to existing datasets. Furthermore, GreatSplicing is available for all
research purposes and can be downloaded from www.greatsplicing.net
In SituâForming Crossâlinking Hydrogel Systems: Chemistry and Biomedical Applications
With the development of chemical synthetic strategies and available building blocks, in situâforming hydrogels have attracted significant attention in the biomedical fields over the past decade. Due to their distinct properties of easy management and minimal invasiveness via simple aqueous injections at target sites, in situâforming hydrogels have found a broad spectrum of biomedical applications including tissue engineering, drug delivery, gene delivery, 3D bioprinting, wound healing, antimicrobial research, and cancer research. The objective of this chapter is to provide a comprehensive review of updated research methods in chemical synthesis of in situâforming crossâlinking hydrogel systems and their diverse applications in the biomedical fields. This chapter concludes with perspectives on the future development of in situâforming hydrogels to facilitate this multidisciplinary field
A Study on the Optimization of Chain Supermarketsâ Distribution Route Based on the Quantum-Inspired Evolutionary Algorithm
The chain supermarket has become a major part of Chinaâs retail industry, and the optimization of chain supermarketsâ distribution route is an important issue that needs to be considered for the distribution center, because for a chain supermarket it affects the logistics cost and the competition in the market directly. In this paper, analyzing the current distribution situation of chain supermarkets both at home and abroad and studying the quantum-inspired evolutionary algorithm (QEA), we set up the mathematical model of chain supermarketsâ distribution route and solve the optimized distribution route throughout QEA. At last, we take Hongqi Chain Supermarket in Chengdu as an example to perform the experiment and compare QEA with the genetic algorithm (GA) in the fields of the convergence, the optimal solution, the search ability, and so on. The experiment results show that the distribution route optimized by QEA behaves better than that by GA, and QEA has stronger global search ability for both a small-scale chain supermarket and a large-scale chain supermarket. Moreover, the success rate of QEA in searching routes is higher than that of GA
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