Group Sparse Precoding for Cloud-RAN with Multiple User Antennas

Cloud radio access network (C-RAN) has become a promising network architecture to support the massive data traffic in the next generation cellular networks. In a C-RAN, a massive number of low-cost remote antenna ports (RAPs) are connected to a single baseband unit (BBU) pool via high-speed low-latency fronthaul links, which enables efficient resource allocation and interference management. As the RAPs are geographically distributed, the group sparse beamforming schemes attracts extensive studies, where a subset of RAPs is assigned to be active and a high spectral efficiency can be achieved. However, most studies assumes that each user is equipped with a single antenna. How to design the group sparse precoder for the multiple antenna users remains little understood, as it requires the joint optimization of the mutual coupling transmit and receive beamformers. This paper formulates an optimal joint RAP selection and precoding design problem in a C-RAN with multiple antennas at each user. Specifically, we assume a fixed transmit power constraint for each RAP, and investigate the optimal tradeoff between the sum rate and the number of active RAPs. Motivated by the compressive sensing theory, this paper formulates the group sparse precoding problem by inducing the $\ell_0$-norm as a penalty and then uses the reweighted $\ell_1$ heuristic to find a solution. By adopting the idea of block diagonalization precoding, the problem can be formulated as a convex optimization, and an efficient algorithm is proposed based on its Lagrangian dual. Simulation results verify that our proposed algorithm can achieve almost the same sum rate as that obtained from exhaustive search

Passive detection of moving aerial target based on multiple collaborative GPS satellites

Passive localization is an important part of intelligent surveillance in security and emergency applications. Nowadays, Global Navigation Satellite Systems (GNSSs) have been widely deployed. As a result, the satellite signal receiver may receive multiple GPS signals simultaneously, incurring echo signal detection failure. Therefore, in this paper, a passive method leveraging signals from multiple GPS satellites is proposed for moving aerial target detection. In passive detection, the first challenge is the interference caused by multiple GPS signals transmitted upon the same spectrum resources. To address this issue, successive interference cancellation (SIC) is utilized to separate and reconstruct multiple GPS signals on the reference channel. Moreover, on the monitoring channel, direct wave and multi-path interference are eliminated by extensive cancellation algorithm (ECA). After interference from multiple GPS signals is suppressed, the cycle cross ambiguity function (CCAF) of the signal on the monitoring channel is calculated and coordinate transformation method is adopted to map multiple groups of different time delay-Doppler spectrum into the distance−velocity spectrum. The detection statistics are calculated by the superposition of multiple groups of distance-velocity spectrum. Finally, the echo signal is detected based on a properly defined adaptive detection threshold. Simulation results demonstrate the effectiveness of our proposed method. They show that the detection probability of our proposed method can reach 99%, when the echo signal signal-to-noise ratio (SNR) is only −64 dB. Moreover, our proposed method can achieve 5 dB improvement over the detection method using a single GPS satellite

Buddhist entrepreneurs, charitable behaviors, and social entrepreneurship : Evidence from China

Acknowledgements We thank the Editor-in-Chief Zoltan J. Acs, David B. Audretsch, the anonymous reviewers, and Shaker A. Zahra and Yong Li for their helpful comments and suggestions.The usual disclaimers apply. Funding The authors acknowledge funding from the National Social Science Foundation of China (grant number: 20AGL008), National Natural Science Foundation of China (grant number: 72172056) and the General Project of Philosophy and Social Science Research in Colleges and Universities of Jiangsu Province (grant number: 2020SJA0254).Peer reviewedPublisher PD

Formal Modeling and Verification of Services Managements for Pervasive Computing Environment

International audienceVarious forms of pervasive computing environments are being deployed in an increasing number of areas including hospitals, homes and military settings. Entities in this environment provide rich functionalities (i.e. services). How to organize these heterogeneous and distributed entities to deliver user-defined services is challenging. Pantagruel is an approach to integrate a taxonomical description of a pervasive computing environment into a visual programming language. A taxonomy describes the relevant entities of a given pervasive computing area and serves as a parameter to a sensor-controller-actuator develop- ment paradigm. The orchestration of area-specific entities is supported by high-level constructs, customized with respect to taxonomical information. Pantagruel is also a language that describes and manages services. Further more, Pantagruel can be viewed as a high level service contract between the service designer and the program implementer. This paper presents a for- malization of Pantagruel, both its syntax and semantics. Four kinds of static properties are stated based on the formalization. Predicate abstraction based algorithms are designed to verify the properties

Entrepreneurship Knowledge : When East meets West

Acknowledgements The lead guest editor would like to express his sincerest thanks to Fabian Jintae Froese, for his excellent patience and guidance of this special issue and his thanks to Robert Wuebker, Qunwan Li, Julio de Castro, Chunhua Chen, Song Lin, and Zuhui Xu who provided very useful helps at different stages of the developments of this special issue and when this editorial paper was developed.Peer reviewedPostprin

Previous military experience and entrepreneurship toward poverty reduction : evidence from China

Acknowledgements We thank the Editor-in-Chief Brandon Randolph-Seng, the anonymous reviewers, and Shaker A. Zahra and Yong Li for their helpful comments and suggestions. We acknowledge funding from the General Project of Philosophy and Social Science Research in Colleges and Universities of Jiangsu Province (grant number: 2020SJA0254). The usual disclaimers apply.Peer reviewedPostprin