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In this paper, a multi-user multi-relay network with wireless energy harvesting (EH) and transferring (ET) is studied. In our system, a simultaneous two-level cooperation, i.e., information-level and energy-level cooperation is conducted for uplink data transmissions (from the users to a destination). Specifically, network coding is employed at the relays to facilitate the information-level cooperation;...
Wireless caching enables popular files to be stored at the base stations (BSs) in advance, which has been considered as an efficient way to reduce the service delay and alleviate heavy burdens on the backhaul links. In this paper, we study the BS clustering scheme for the cooperative wireless caching networks (CWCNs) with heterogeneous file preference among users and BSs, and propose the minimum cost...
This paper investigates the asymptotic performance of bit-interleaved coded modulation (BICM) with iterative multiuser detection and decoding in uplink sparse code multiple access (SCMA) systems. The extrinsic information transfer (EXIT) characteristics analysis of the joint multiuser detector for SCMA is provided, and shows that the average detection reliability for multiple users converges to the...
To overcome the severe path loss and provide higher spectral efficiency for 60 GHz wireless communications, highly directional antennas, which indicate high antenna gains, are widely employed. In this work, we focus on the trade-off between the beamwidth of directional antennas and the interference produced by random concurrent transmissions, in terms of two important statistics, i.e., the expectation...
With the increasingly severe of the energy and environmental problems, wind energy as a kind of clean and renewable energy has become more and more important. Semi-direct drive wind turbines have a good application potential due to their superior properties for wind power generation. As the key components, the planetary gearbox is commonly used in the wind generator, which sustains low speed, heavy...
Wireless sensor networks (WSNs) consist of energy limited sensor nodes, which limits the network lifetime. Such a lifetime can be prolonged by employing the emerging technology of wireless energy transfer (WET). In WET systems, the sensor nodes can harvest wireless energy from wireless charger, which can use energy beamforming to improve the efficiency. In this paper, a scenario where dedicated wireless...
The lifetime of a wireless sensor network (WSN) is limited by the lifetime of the individual sensor nodes. A promising technique to extend the lifetime of the nodes is wireless energy transfer. The WSN lifetime can also be extended by exploiting the redundancy in the nodes' deployment, which allows the implementation of duty-cycling mechanisms. In this paper, the joint problem of optimal sensor node...
Consider a distributed storage system where parts of the source file fragments in storage nodes are lost. We denote a storage node that lost a part of its fragments as a faulty storage node and a storage node that lost non of its fragment as a complete storage node. In a process, termed as partial repair, a set of storage nodes (among faulty and complete storage nodes) transmit repairing fragments...
In an underlay cognitive radio network, the cross- channel gain from a cognitive transmitter (CT) to a primary receiver (PR) is crucial for spectrum sharing. By exploiting the relaying capability of the CT, we propose a proactive estimation scheme for the cross-channel gain. In particular, the CT proactively acts as a full-duplex amplify-and- forward (AF) relay for primary transceivers to trigger...
To meet the ever-increasing demands on higher throughput and better network delay performance, 60 GHZ networking is proposed as a promising solution for the next generation of wireless communications. To successfully deploy such networks, its important to understand their performance first. However, due to the unique fading characteristic of the 60 GHz channel, the characterization of the corresponding...
This paper discusses how to apply a hybrid computation process comprised by three techniques of Artificial Neural Network (ANN), Bayesian probability and Cellular Automata (CA), to establish simulating model which can embody the advantages of perceptron, stochastic and dynamic. Through our hybrid computation process, we can perform a series of dynamic simulations with high accuracy. Additionally,...
The problem of the centralized caching is studied in a two-layer network. The first layer of the network is constructed by a server and K1 helpers, and the second layer consists of K1 orthogonal sub-networks, each of which contains a helper and K2 users. The pioneer caching design in the two-layer network is to directly apply the Maddah-Ali & Niesen (MAU) centralized caching [1] into individual...
Partial discharge (PD) ultra-high frequency (UHF) sensors are widely used for condition monitoring and defect location in gas insulated substation (GIS). There are many designs of UHF sensors which can detect electromagnetic waves that radiate from PD sources. The general types of UHF sensors are disc, monopole, probe, spiral, and conical types with each type of sensor having different characteristics...
Hundreds of features have been extracted from phase resolved partial discharge (PRPD) pattern and PD waveforms to represent and recognize typical defects. Several feature selection and dimension reduction methods for pattern recognition are presented in this paper. Feature selection algorithms including forward feature selection, backward feature selection and floating forward feature selection (FFFS)...
Ultra-high-frequency (UHF) method has been applied to detect and localize partial discharge (PD) in air-insulated substation (AIS). The localization accuracy is closely dependent on the configuration of antenna array. This paper presents a PD localization error simulation method. Assuming that the estimated time difference of arrival (TDOA) error is normally distributed, the mean value and standard...
While the size of electronic devices continues to decrease and the I/O number per chip keeps increasing, the size and pitch of solder bumps are required to be as small as possible. This case gives rise to great concerns on their quality and reliability. As a 3D integration alternative to solder bumps, Cu-pillars have been proposed due to their better electromigration-resistance and other performance...
The decentralized caching is studied in hierarchical networks, where users request contents through intermediate nodes (helpers) from a file server. By placing contents randomly and independently in each node and carefully designing the data delivery, the correlations of the pre-stored contents across layers can be utilized to reduce the transmission rate in each layer. A hybrid caching scheme is...
In Wireless Sensor Networks (WSNs), to supply energy to the sensor nodes, wireless energy transfer (WET) is a promising technique. One of the most efficient procedures to transfer energy to the sensor nodes consists in using a sharp wireless energy beam from the base station to each node at a time. A natural fundamental question is what is the lifetime ensured by WET and how to maximize the network...
We investigate the energy efficiency (EE) in cognitive radio networks, where cognitive users are allowed to access the licensed frequency band opportunistically, provided that the licensed band is vacant. In particular, we study the impact of imperfect spectrum sensing and formulate the EE maximization as a joint optimization problem of the spectrum sensing duration and the transmit power of the cognitive...
In this paper, the energy efficiency (EE) of a cooperative diversity system with maximum diversity network coding (MDNC) is studied. In the considered system, channel state information (CSI) is only available at the receivers for all the channels. We formulate the problem of maximizing the EE under the constraint on the outage probability. The problem is NP-hard due to the non-convexity of the outage...
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