Jia You

Security and Reliability Performance Analysis for Cloud Radio Access Networks With Channel Estimation Errors

Physical layer (PHY) security is recently regarded as a promising technique to improve the security performance of wireless communication networks. Current developments in PHY security are often based on the assumption of perfect channel state information (CSI). In this paper, both security and reliability performance for the downlink cloud radio access network with optimal remote radio heads (RRHs) node selection are investigated in a practical scenario by considering channel estimation (CE) errors. In particular, a three-phase transmission scheme is proposed and the linear minimum mean-square error (MMSE) estimation method is utilized to obtain the CSI. Based on the CSI estimates and the statistics of CE errors, the outage probability and intercept probability are derived in closed-form expression to evaluate the security and reliability performance, respectively. In addition, two possible cases (with or without intercepting signals from baseband unit) are considered for the eavesdropper. It is found that the suggested optimal RRHs selection scheme outperforms the nonselection scheme, and that the increasing number of RRHs can lower the outage probability as well as the intercept probability. It is also shown that there exists an optimal training number to minimize the sum of the outage probability and intercept probability. Finally, simulation results are provided to corroborate our proposed studies.

Transmission schemes for high-speed railway: Direct or relay?

Two transmission schemes exist in wireless communication system for high-speed railway: the direct transmission and relay-based transmission. The main purpose of this paper is to evaluate the performance of these two transmission schemes. Specifically, the closed-form expressions of ergodic capacity for each transmission scheme are derived. By comparing these obtained capacity expressions, we find that the relay-based transmission has better performance in the low and intermediate SNR, while the direct transmission becomes a better choice at high SNR. It is also shown that the signal amplitude loss resulted from signal traversing through the carriage is a key parameter in determining the ergodic capacity for direct transmission scheme. Finally, the simulation results demonstrate an exact match with our theoretical findings.

Location assistant beamforming for high speed railway

In this paper, we introduce an algorithm of location assistant direction of departure (DOD) based beamforming scheme which is suitable for wireless communication in highspeed railway (HSR). The beamforming weights are calculated according to the locations of mobile station (MS) and base station (BS) together with the topology of multiple transmit antennas. The purpose of the algorithm is to make phase adjustment at the transmitter such that the output signal-to-noise ratio (SNR) at the receiver can be improved. The performance of beamforming with ideal DOD and estimated DOD which has deviation caused by location errors are both evaluated. Results show that beamforming with ideal DOD greatly outperforms all other transmission modes, i.e., transmit diversity and single-input single-output (SISO), while the inevitable DOD estimation error degrades the overall performance.

Propagation and Wireless Channel Modeling Development on Wide-Sense Vehicle-to-X Communications

The need for improving the safety and the efficiency of transportation systems has become of extreme importance. In this regard, the concept of vehicle-to-X (V2X) communication has been introduced with the purpose of providing wireless communication technology in vehicular networks. Not like the traditional views, the wide-sense V2X (WSV2X) communications in this paper are defined by including not only vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications but also train-to-X (T2X) communications constituted of train-to-train (T2T) and train-to-infrastructure (T2I) communications. All the information related to the wide-sense V2X channels, such as the standardization, scenarios, characters, and modeling philosophies, is organized and summarized to form the comprehensive understanding of the development of the WSV2X channels.

Wireless relay communication on high speed railway: Full duplex or half duplex?

In this paper, we introduce one full-duplex (FD) relaying transmission scheme for high speed railway and compare its ergodic capacity and outage performance with half-duplex (HD) relaying scheme. Both decode-and-forward (DF) amplify-and-forward (AF) relay modes are considered. Moreover, the carriage penetration loss (CPL) and the self-interference (SI) cancellation ratio are investigated. We derive the closed-form expressions for the outage probability and ergodic capacity of both HD and FD relay transmission schemes. It is shown that when CPL is larger than a certain level, the FD relay can achieve better performance in terms of capacity and keep the outage probability in a low level. It is also found that three factors: AF or DF modes, CPL and SI cancellation ratio, can have impact on capacity performance, and that CPL is one decisive factor. Our results can provide theoretical supports for development and deployment of future wireless communication systems on high speed railways.

On the conditioning channel capacity of MIMO two-way relay networks against eavesdropper

In this paper, we consider the two-way relay network (TWRN) in the presence of an eavesdropper, and construct a noisy amplify-and-forward (AF) algorithm to enhance the physical (PHY) layer security capacity. All the source nodes, the relay and the eavesdropper are equipped with multiple antennas. In the proposed noisy AF scheme, the relay first receives signals from both source nodes, adds weighted artificial noise (AN), and then amplifies and forwards the modified signal to both source nodes. In this scenario, we analyze the effects of AN and the number of relay antennas on the secrecy sum rate for different conditioning channel matrices. It is shown that AN will result in an increased secrecy sum rate, and the channel condition is a key parameter of the system in deciding the sum secrecy rate. Finally, simulation results demonstrate the validity of proposed studies.

Security-Reliability Tradeoff for Relay Networks in the Presence of Channel Estimation Error

In this work, a two-phase optimal-relay transmission scheme for relay networks against eavesdropper is proposed. The security and the reliability performance of this scheme are evaluated in the form of the intercept probability and the outage probability, respectively. In addition, the closed-form expression of security-reliability tradeoff (SRT) is obtained to show the compromise of the security and reliability performance of the system. Specifically, instead of common assumptions of perfect global channel state information in most literature, the channel estimation error and its effects on performance analysis are considered in this paper. It is shown that the security (or reliability) can be enhanced by degrading the reliability (or security) requirement, and the performance can be improved by increasing the number of relays. Finally, simulation results are provided to corroborate our proposed studies.

Security-Reliability Analysis for Cloud Radio Networks with Channel Estimation Error

In this paper, we introduce a three-phase transmission scheme for cloud radio networks against eavesdropper. We study the security and reliability performance of this scheme in the form of intercept probability and outage probability, respectively. Channel estimation error is considered in our study instead of assumption of perfect channel state information. It is found that the security-reliability performance improves as the number of relay increases. Moreover, the length of training symbol considerably influences the performance. Simulation results are provided to corroborate our studies.

Performance analysis for selective cooperation transmission in high-speed railway

A key factor that decreases the performance of the high-speed railway is the loss of power when the signal traverses through the carriage. We consider two new schemes in wireless communication system in high-speed railway network: the direct noncooperative transmission scheme and relay-based cooperative transmission scheme and study a selective cooperation scheme combine the two transmission schemes together. The main goal of this paper is to derive the closed-form outage probabilities of the two schemes, and evaluate the performance of them. Comparing results show that the selective cooperation transmission outperforms than the noncooperative direct transmission and can obtain better reliability. Moreover, the signal power loss resulted from the new type of the carriage of the high-speed railway is a key metric to determine the outage probability and performance for each transmission scheme.