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The performance of fingerprint based indoor localization techniques is significantly degraded by environmental dynamics especially when devices such as Wi-Fi access points (APs), which are used to build fingerprint database, are densely deployed. The primary reason is that the plug-and-play feature of these devices would render the fingerprints in the database invalid. Worsestill, the time-varying...
In this paper, two dimensional angle estimation using a new array structure named separate nested acoustic vector sensor (AVS) array is studied. Unlike traditional AVS array, where the pressure sensor and velocity sensors are collocated in space, the separate nested AVS array has two separate and nested subarrays including the pressure sensor array and the velocity vector sensor array. With the extended...
Recently, a switch-based hybrid massive MIMO structure that aims to reduce the hardware complexity and power consumption has been proposed as a potential candidate for millimeter wave (mmWave) communications. In this paper, we investigate a matrix completion (MC)-based low-complexity channel estimator for such systems, which is compatible with the switch-based hybrid structure. We conduct a thorough...
As one of the major radio-frequency impairments in multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system, in-phase and quadrature-phase (IQ) imbalance tends to destroy the reciprocity between uplink and downlink channel based on time-division duplex (TDD) mode and deteriorate system performance. In this paper, a time-domain calibration scheme is proposed to...
Face detection is an important step in face recognition. Ineffective algorithm used for face detection will have a negative impact on the performance of face recognition. Face detection technology is not only a key step in face recognition technology, but also is an independent widely-used technology. It is important to design a suitable feature for face detection technology. This paper proposes a...
To enhance the capacity and spectrum efficiency of existing satellite resources, cooperative transmissions are widely considered in geostationary orbit satellite collocation (GEOSC) systems. However, the existing cooperative transmission methods mainly focus on two-satellite GEOSC systems, which might not be helpful to improve the performance of a multi-satellite collocation (MSC) system. In this...
Massive machine type communication (mMTC) is one of the three significant scenarios in 5G, which is characterized by massive connection and low energy consumption. To meet these requirements, the contention based grant-free sparse code multiple access (SCMA) transmission which can support a large number of devices and reduce the cost of signaling overhead caused by massive connection is proposed....
Due to the limited frequency and energy resources, cooperative satellite communication (SATCOM) systems have been widely studied. To improve the spectrum efficiency further, we propose to combine non-orthogonal multiple access (NOMA) with cooperative SATCOM systems in this paper. Under the condition of fixed total transmit power, an optimization problem is formulated to maximize the sum-rate with...
In this paper, we propose a systematic design approach of polar codes for multicolor visible light communication (VLC). Owing to the mixed ratio of multicolor light intensities and the interference between different colors, the channel polarization over a multicolor VLC system is markedly different from that over a uniform channel. Our scheme quantifies these different color channels and constructs...
In this paper, we improve the direction finding accuracy for shortwave fixed stations located in imperfect environment. A correction method of direction finding data is proposed based on least square algorithm. Firstly, we establish the mathematical model of the relationship between real azimuthal angles and errors according to the statistical features of direction finding data. Then we design model...
For long-distance transmissions, relay-aided transmission technique is a promising solution to improve the performance for the free-space optical (FSO) communications. In this paper, a serial decode-and-forward relay-aided FSO communication system is considered. In the system, the main noise is Gaussian noise, however, with a noise variance depending on the current signal strength. Moreover, a composite...
We consider a two-way cognitive radio relay network where two secondary users (SUs) can simultaneously transfer energy and information to a relay. Then, a joint optimization algorithm for power allocation and energy cooperation is proposed. The algorithm proves that the formulated throughput maximization problem is a convex optimization problem. Next, we decompose the formulated problem into a power...
Fog Radio Access Network(F-RAN) is a promising technique for the fifth generation mobile communication system to provide high spectral and energy efficiency. In comparison with Cloud Radio Access Network, the Radio Units in F-RAN are equipped with local caches, which store popular content. In this paper, we investigate joint cooperative beamforming and radio units (RUs) operation in F-RAN system to...
Collecting data in time is crucial for the wireless sensor network (WSN), especially for some WSNs who suffer from inconstant link connections. Our observations in the intertidal wireless sensor network (IT-WSN) reveal that end-to-end delay is severe and a big challenge to be solved. Existing routing protocols perform well in WSNs with good link quality but show deficiency when node states change...
Vehicular Ad hoc Network(VANET), an infusive area for the development of Intelligent Transportation System (ITS), is going to be a significant communication pattern in our moving life. Data dissemination is an important part of VANETs. The demand of disseminate commercial advertisements in moving cars emerges. To satisfy the demand of shopping in car, we proposed a new data dissemination scheme in...
In this paper, we study the energy-efficient user access control (UAC) based on resource allocation (RA) in heterogeneous cellular networks (HCNs) with the required downlink data rate under non-ideal power amplifiers (PAs) and circuit power. It is proved that the energy consumption minimization is achieved when the typical user accesses only one base station (BS), while the other BSs remain in idle...
Physical layer security is becoming a promising technology to face the security challenges of diversified and rapidly-growing wireless applications. In this paper, we propose a three-hop secure Orthogonal Frequency Division Multiplexing (OFDM) transmission protocol for the wireless networks with untrusted relays. In the proposed protocol, instead of exploiting the degree of freedom over spatial domain...
In this paper, we study the problem of secret key generation with one-way communication, where in addition to the rate limited public channel, which can be observed by both Bob and Eve, we add a secure channel, which only connects Alice and Bob. In this model, we do not pose any constraints on the sources, i.e. Bob is not degraded to or less noisy than Eve. We propose an achievability scheme, and...
In this paper, we propose a novel m-th best average biased received power (ABRP) user association (UA) scheme for K-tier heterogeneous networks (HetNets), where a user is associated with the base station (BS) having the m-th strongest ABRP. For this novel scheme, by using stochastic geometry and modeling the positions of network elements in each tier as a homogeneous Poisson point process (PPP), we...
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