22,794 research outputs found
Transmission Schemes based on Sum Rate Analysis in Distributed Antenna Systems
In this paper, we study single cell multi-user downlink distributed antenna
systems (DAS) where antenna ports are geographically separated in a cell.
First, we derive an expression of the ergodic sum rate for the DAS in the
presence of pathloss. Then, we propose a transmission selection scheme based on
the derived expressions which does not require channel state information at the
transmitter. Utilizing the knowledge of distance information from a user to
each distributed antenna (DA) port, we consider the optimization of pairings of
DA ports and users to maximize the system performance. Based on the ergodic sum
rate expressions, the proposed scheme chooses the best mode maximizing the
ergodic sum rate among mode candidates. In our proposed scheme, the number of
mode candidates are greatly reduced compared to that of ideal mode selection.
In addition, we analyze the signal to noise ratio cross-over point for
different modes using the sum rate expressions. Through Monte Carlo
simulations, we show the accuracy of our derivations for the ergodic sum rate.
Moreover, simulation results with the pathloss modeling confirm that the
proposed scheme produces the average sum rate identical to the ideal mode
selection with significantly reduced candidates.Comment: 25 pages, 8 figures, submitted to IEEE Transactions on Wireless
Communications, May 201
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
- …