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For the specific propagation characteristics of millimeter wave, in this paper, we study the beamforming design and interference management in millimeter wave cellular networks with partial channel state information (CSI). Specifically, we propose two beamforming schemes, namely eigen beamforming and orthogonal beamforming, based on the information of channel covariance matrix, and analyze the intercell...
Due to the low out-of-band emission and robustness against asynchronous transmissions, generalized frequency division multiplexing (GFDM) has potential to be a new modulation scheme for the foreseeable applications. In this paper, a novel precoding scheme with tunable band sizes is proposed for GFDM systems. The precoder and equalizer are jointly designed aiming at minimizing the system total mean...
Listen-Before-Talk category 4 (LBT Cat4) mechanism is considered as the most appropriate access method for Licensed-Assisted Access (LAA) framework, especially when LAA system coexists with WiFi system in unlicensed bands. Previous investigations of the LBT Cat4 based LAA-WiFi coexistence provide experimental results and simulation results, and theoretical analysis work is relatively rare. This work...
Sparse-code multiple-access (SCMA) is a novel multiplexing method to increase the capacity of wireless communication systems. By giving users non-orthogonal codebook with few non-zero entries, the SCMA approach can highly improve the spectral efficiency, compared with traditional orthogonal ones such as CDMA, with tolerable detection complexity. Therefore, it has been considered as an option for 5G...
Invisibility and robustness are two important performance indicators of watermarking algorithm. To improve the performance of watermarking algorithms, the visual model is introduced, and the most classic is the Watson model. However, the original Watson model is defective in resisting amplitude scaling. In this paper, we will propose a new improvement of the Watson model to overcome its shortcomings...
Inter-cell interference is one of important factors in drone small cells (DSCs). However, most works investigated the network performance of DSC networks with an assumption of interference-free. To achieve a realistic analysis, we analyze the coverage probability and achievable rate of DSC networks under inter-cell interference. However, the air-to-ground channel between DSCs and ground users consists...
Due to the open access nature of wireless communication environment, physical layer security has brought increasingly high attention in recent years, attempting to protect the confidential communication away from eavesdroppers. In contrast to the current secrecy designs, which generally exploit the spatial Degree-of-Freedom (DoF) (e.g. MIMO and cooperative relay approaches) or the temporal DoF (e...
In this paper, we study multiuser detection for asynchronous uplink machine-to-machine systems with code division multiple access. We formulate the maximal logarithmic likelihood problem for asynchronous multiuser detection via joint channel gains, time delays and transmission symbols detection. We present the design for pilot sequence and propose an adaptive step-size method with low complexity to...
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...
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...
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...
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...
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