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Wireless Communications and Mobile Computing
Volume 2017 (2017), Article ID 9580639, 11 pages
https://doi.org/10.1155/2017/9580639
Research Article

Secrecy Analysis of Multiuser Untrusted Amplify-and-Forward Relay Networks

1School of Information Engineering, Guangzhou Panyu Polytechnic, Guangzhou 511483, China
2Department of Electronic Engineering, Shantou University, Shantou 515063, China
3School of Computer Science and Educational Software, Guangzhou University, Guangzhou 510006, China
4College of Information Science and Technology, Nanjing Forestry University, Nanjing 210037, China
5Department of Electrical and Computer Engineering, Utah State University, Logan, UT 84322-4120, USA
6Jiangsu Engineering Centre of Network Monitoring and School of Computer and Software, Nanjing University of Information Science and Technology, Nanjing 210044, China

Correspondence should be addressed to Lisheng Fan

Received 16 July 2016; Revised 18 September 2016; Accepted 13 October 2016; Published 15 January 2017

Academic Editor: Gonzalo Vazquez-Vilar

Copyright © 2017 Dan Deng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper investigates the secure communications of multiuser untrusted amplify-and-forward relay networks in the presence of direct links. In the considered system, one user is selected among multiple ones for secure transmission to the destination node with the help of an untrusted relay node. To reduce the information leakage to the untrusted relay, the paper considers two selection criteria to select the user based on the direct and the relaying links, respectively. The impact of direct and the relaying link on the system secrecy performance is studied by deriving the close-form ergodic secrecy rate (ESR) as well as the asymptotic expression. From the asymptotic expression, it can be found that the asymptotic ESR increases linearly with the logarithm of the average channel gain ratio of the direct link to the relaying link.