892 research outputs found
Performance Analysis for 5G cellular networks: Millimeter Wave and UAV Assisted Communications
Recent years have witnessed exponential growth in mobile data and traffic. Limited available spectrum in microwave (Wave) bands does not seem to be capable of meeting this demand in the near future, motivating the move to new frequency bands. Therefore, operating with large available bandwidth at millimeter wave (mmWave) frequency bands, between 30 and 300 GHz, has become an appealing choice for the fifth generation (5G) cellular networks. In addition to mmWave cellular networks, the deployment of unmanned aerial vehicle (UAV) base stations (BSs), also known as drone BSs, has attracted considerable attention recently as a possible solution to meet the increasing data demand. UAV BSs are expected to be deployed in a variety of scenarios including public safety communications, data collection in Internet of Things (IoT) applications, disasters, accidents, and other emergencies and also temporary events requiring substantial network resources in the short-term. In these scenarios, UAVs can provide wireless connectivity rapidly.
In this thesis, analytical frameworks are developed to analyze and evaluate the performance of mmWave cellular networks and UAV assisted cellular networks. First, the analysis of average symbol error probability (ASEP) in mmWave cellular networks with Poisson Point Process (PPP) distributed BSs is conducted using tools from stochastic geometry. Secondly, we analyze the energy efficiency of relay-assisted downlink mmWave cellular networks. Then, we provide an stochastic geometry framework to study heterogeneous downlink mmWave cellular networks consisting of tiers of randomly located BSs, assuming that each tier operates in a mmWave frequency band. We further study the uplink performance of the mmWave cellular networks by considering the coexistence of cellular and potential D2D user equipments (UEs) in the same band. In addition to mmWave cellular networks, the performance of UAV assisted cellular networks is also studied. Signal-to-interference-plus-noise ratio (SINR) coverage performance analysis for UAV assisted networks with clustered users is provided. Finally, we study the energy coverage performance of UAV energy harvesting networks with clustered users
Coverage Analysis of Relay Assisted Millimeter Wave Cellular Networks with Spatial Correlation
We propose a novel analytical framework for evaluating the coverage
performance of a millimeter wave (mmWave) cellular network where idle user
equipments (UEs) act as relays. In this network, the base station (BS) adopts
either the direct mode to transmit to the destination UE, or the relay mode if
the direct mode fails, where the BS transmits to the relay UE and then the
relay UE transmits to the destination UE. To address the drastic rotational
movements of destination UEs in practice, we propose to adopt selection
combining at destination UEs. New expression is derived for the
signal-to-interference-plus-noise ratio (SINR) coverage probability of the
network. Using numerical results, we first demonstrate the accuracy of our new
expression. Then we show that ignoring spatial correlation, which has been
commonly adopted in the literature, leads to severe overestimation of the SINR
coverage probability. Furthermore, we show that introducing relays into a
mmWave cellular network vastly improves the coverage performance. In addition,
we show that the optimal BS density maximizing the SINR coverage probability
can be determined by using our analysis
A Survey of Physical Layer Security Techniques for 5G Wireless Networks and Challenges Ahead
Physical layer security which safeguards data confidentiality based on the
information-theoretic approaches has received significant research interest
recently. The key idea behind physical layer security is to utilize the
intrinsic randomness of the transmission channel to guarantee the security in
physical layer. The evolution towards 5G wireless communications poses new
challenges for physical layer security research. This paper provides a latest
survey of the physical layer security research on various promising 5G
technologies, including physical layer security coding, massive multiple-input
multiple-output, millimeter wave communications, heterogeneous networks,
non-orthogonal multiple access, full duplex technology, etc. Technical
challenges which remain unresolved at the time of writing are summarized and
the future trends of physical layer security in 5G and beyond are discussed.Comment: To appear in IEEE Journal on Selected Areas in Communication
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