Fang Xiaojie

MP-WFRFT and constellation scrambling based physical layer security system

In this paper, a multiple parameters weighted fractional Fourier transform (MP-WFRFT) and constellation scrambling (CS) method based physical layer (PHY) security system is proposed. The proposed scheme is executed by two steps. In the first step, MP-WFRFT, implemented as the constellation beguiling (CB) method, is applied to change the signals identity. In the second step the additional pseudo random phase information, regarded as the encryption key, is attached to the original signal to enhance the security. Typically, the pseudo random phase information can be removed effectively by the legitimate receiver. In contrast to the cryptography based encryption algorithms and the conventional PHY secrecy techniques, the main contribution of the proposed scheme is concentrated on the variation in signals characteristics. Simulation results show that the proposed scheme can prevent the exchanging signal from eavesdroppers classification or inception. Moreover, the proposed scheme can guarantee the BER performance at a tolerate increasing in computational complexity for the legitimate receivers.

Secret Communication Using Parallel Combinatory Spreading WFRFT

In this letter, a parallel-combinatory-spreading-based weighted fractional Fourier transform (PCS-WFRFT) system aiming to guarantee physical layer (PHY) security is proposed. In this system, the transmission data are first divided into two groups. Based on the first group of data, a set of pseudonoise sequences is generated and then used to spread and encrypt the second group of data. In general, the proposed system is spread and dynamically encrypted by the message information itself, whereby both high bandwidth efficiency and high security performance are obtained. Numerical simulations are conducted to evaluate the performance of the proposed system in terms of the average bit error rate.

A mobile relay selection strategy in cooperative spectrum sharing framework

In spectrum sharing networks with relay cooperation, primary users can benefit from the assistance of secondary users while secondary users accessing the primary bandwidth to transmit their signals. Reasonable relay selection strategy can improve the performances of both primary and secondary users in terms of higher transmission data rate and lower outage probability, and at the same time, frequent relay switching can be avoided. In this paper, we propose a relay selection strategy considering both relay mobility and the required transmission data rate of primary user. The metrics of relay selection combine the relay activation duration and the transmission data rate of the secondary users through the mobility prediction of relay nodes. Simulation results show that the proposed strategy can select the best relay with lower primary outage probability and longer relay activation duration compared with existing schemes, and the transmission data rate of secondary user can also be improved so that the total number of transmit information bits can be increased.In spectrum sharing networks with relay cooperation, primary users can benefit from the assistance of secondary users while secondary users accessing the primary bandwidth to transmit their signals. Reasonable relay selection strategy can improve the performances of both primary and secondary users in terms of higher transmission data rate and lower outage probability, and at the same time, frequent relay switching can be avoided. In this paper, we propose a relay selection strategy considering both relay mobility and the required transmission data rate of primary user. The metrics of relay selection combine the relay activation duration and the transmission data rate of the secondary users through the mobility prediction of relay nodes. Simulation results show that the proposed strategy can select the best relay with lower primary outage probability and longer relay activation duration compared with existing schemes, and the transmission data rate of secondary user can also be improved so that the total number of transmit information bits can be increased.