Beijing University of Posts and Telecommunications

About: Beijing University of Posts and Telecommunications is a education organization based out in Beijing, Beijing, China. It is known for research contribution in the topics: MIMO & Quality of service. The organization has 39576 authors who have published 41525 publications receiving 403759 citations. The organization is also known as: BUPT.

Secrecy Analysis of Ambient Backscatter NOMA Systems Under I/Q Imbalance

Abstract: In this correspondence, we investigate the reliability and the security of the ambient backscatter (AmBC) non-orthogonal multiple access (NOMA) systems, where the source aims to communicate with two NOMA users in the presence of an eavesdropper. To be practical, we assume that all nodes and backscatter device (BD) suffer from in-phase and quadrature-phase imbalance (IQI). More specifically, some analytical expressions for the outage probability (OP) and the intercept probability (IP) are derived. In order to obtain more insights, the asymptotic behaviors for the OP in the high signal-to-noise ratio (SNR) regime are explored, and corresponding diversity orders are derived. Numerical results show that: 1) Although IQI reduces the reliability, it can enhance the security; 2) Compared with the orthogonal multiple access (OMA) systems, the considered AmBC NOMA systems can obtain better reliability when the SNR is lower; 3) There are error floors for the OP in the high SNR regime due to the reflection coefficient $\beta$ ; 4) There exists a trade-off between reliability and security.

Authentication of Smartphone Users Based on Activity Recognition and Mobile Sensing.

Abstract: Smartphones are context-aware devices that provide a compelling platform for ubiquitous computing and assist users in accomplishing many of their routine tasks anytime and anywhere, such as sending and receiving emails. The nature of tasks conducted with these devices has evolved with the exponential increase in the sensing and computing capabilities of a smartphone. Due to the ease of use and convenience, many users tend to store their private data, such as personal identifiers and bank account details, on their smartphone. However, this sensitive data can be vulnerable if the device gets stolen or lost. A traditional approach for protecting this type of data on mobile devices is to authenticate users with mechanisms such as PINs, passwords, and fingerprint recognition. However, these techniques are vulnerable to user compliance and a plethora of attacks, such as smudge attacks. The work in this paper addresses these challenges by proposing a novel authentication framework, which is based on recognizing the behavioral traits of smartphone users using the embedded sensors of smartphone, such as Accelerometer, Gyroscope and Magnetometer. The proposed framework also provides a platform for carrying out multi-class smart user authentication, which provides different levels of access to a wide range of smartphone users. This work has been validated with a series of experiments, which demonstrate the effectiveness of the proposed framework.

Outage Probability of Decode-and-Forward Cognitive Relay in Presence of Primary User's Interference

Abstract: In the presence of the primary user's interference, the outage probability of a dual-hop decode-and-forward (DF) cognitive relay network (CRN) over Rayleigh fading channels is investigated. We first derive the exact expression for the outage probability, using which the impact of different system parameters on the outage performance is presented in the asymptotic regimes. In addition, the asymptotic outage probability is also derived in the high signal-to-noise ratio (SNR) regime.

Broadband Photonic Radio-Frequency Channelization Based on a 39-GHz Optical Frequency Comb

Abstract: A novel photonic channelization scheme for a wideband radio-frequency (RF) signal based on an optical frequency comb (OFC), a comb filter, and an optical de-mux is proposed and demonstrated. In the proposed channelizer, the input broadband RF signal is multicast by the OFC, spectrally sliced by a Fabry-Perot filter (FPF) and then channelized by a regular optical de-mux. Compared to previous proposals, the OFC can provide uniform and low-noise channelization and simplify the spectral alignment to the FPF. We demonstrate our scheme experimentally based on a 39-GHz-spaced OFC. As an application, instantaneous multiple-frequency measurement is demonstrated by directly detecting the channelized RF signal.