Jie Tang

Simple Adaptive Single Differential Coherence Detection of BPSK Signals in IEEE 802.15.4 Wireless Sensor Networks

In this paper, we propose an adaptive single differential coherent detection (SDCD) scheme for the binary phase shift keying (BPSK) signals in IEEE 802.15.4 Wireless Sensor Networks (WSNs). In particular, the residual carrier frequency offset effect (CFOE) for differential detection is adaptively estimated, with only linear operation, according to the changing channel conditions. It was found that the carrier frequency offset (CFO) and chip signal-to-noise ratio (SNR) conditions do not need a priori knowledge. This partly benefits from that the combination of the trigonometric approximation sin−1(x)≈x and a useful assumption, namely, the asymptotic or high chip SNR, is considered for simplification of the full estimation scheme. Simulation results demonstrate that the proposed algorithm can achieve an accurate estimation and the detection performance can completely meet the requirement of the IEEE 802.15.4 standard, although with a little loss of reliability and robustness as compared with the conventional optimal single-symbol detector.

Adaptive Secure Transmission for Physical Layer Security in Cooperative Wireless Networks

We investigate the physical layer security in cooperative wireless networks where a source (Alice) transmits a confidential message to a destination (Bob) with the help of a cooperative node (Charlie), in the presence of an eavesdropper (Eve). Cooperative transmission is explored to secure communication between Alice and Bob, while ensuring the desired quality of service (QoS) at Charlie’s receiver. We provide a transmit design for outage constrained secrecy rate maximization, taking both security and QoS constraints into account. Unlike the conventional cooperative security that adopts a fixed transmission scheme, we propose a mechanism for transmit strategy adaptation with security protection. Specifically, the proposed cooperative transmission is replaced by a cooperative jamming scheme if either security or QoS constraint is not satisfied. Numerical results confirm that our design enables dynamic transmission, and thus is flexible and environment-adaptive.

Outage constrained secrecy rate maximization using artificial-noise aided beamforming and cooperative jamming

In this paper, we consider physical layer security in wireless communication networks in which a source (Alice) intends to send a confidential message to a legitimate destination (Bob) with the help of a cooperative jammer (CJ), in the presence of a passive eavesdropper (Eve). Assuming that only statistical channel state information (CSI) of Eve is available, artificial-noise (AN) assisted beamforming and cooperative jamming are designed. The goal is to maximize the secrecy rate, subject to a constraint on secrecy outage probability. Numerical results validate the effectiveness of our scheme. Moreover, a higher secure energy efficiency (EE) can be achieved as compared with other schemes without a cooperative jammer.

Associating MIMO beamforming with security codes to achieve unconditional communication security

This study investigates the framework of associating multiple-input–multiple-output (MIMO) beamforming with secure code to achieve unconditional secure communications in the wireless passive eavesdropping environment. The schemes are based on a two-step method under Wyners wiretap channel model. First, with MIMO transmit beamforming, one can utilise the spatial degree of freedom to cripple eavesdroppers’ interceptions even when he does not know the eavesdroppers channel state information. Consequently, by taking the threshold characteristics of the secure code, the legitimate receivers will continue to extend an average bit error rate advantage over eavesdroppers when they share similar conditions (background noise power and channel gains). By this way, the proposed system could achieve almost zero information obtained by the eavesdroppers while still keeping rather lower error transmissions for the main channel. A profound theoretical analysis for the MIMO advantage channel and the exact closed-form expressions of secrecy outage probability for the secure code joint system are presented. The authors launch extensive experiments to verify the proposed security systems and demonstrate its feasibility and implement ability.

Adaptive Base Station Cooperation for Physical Layer Security in Two-Cell Wireless Networks

We study physical layer security in two-cell wireless networks in which a base station (Alice) intends to send a confidential message to a legitimate user (Bob) with the help of a cooperative base station (Charlie), in the presence of an eavesdropper (Eve). Adaptive base station cooperation is explored to secure communication between Alice and Bob, and ensure the desired quality of service (QoS) at Charlies user. In particular, we consider two different scenarios where the channel state information of Eve is perfectly and statistically known, respectively. In either scenario, we provide a cooperative transmission scheme for secrecy rate maximization, subject to both security and QoS constraints. Unlike the conventional cooperative security with a fixed transmission scheme, we propose a mechanism for transmit strategy adaptation with security protection. Specifically, the cooperative transmission is replaced by a cooperative jamming scheme if either security or QoS constraint is not satisfied. Our design enables adaptive secure transmission, and thus is flexible and environment-adaptive. Moreover, numerical results confirm that our scheme is efficient in power resource utilization.

A MIMO Cross-layer Precoding Security Communication System

This paper proposed a MIMO cross-layer precoding secure communications via pattern controlled by higher layer cryptography. By contrast to physical layer security system, the proposed scheme could enhance the security in adverse situations where the physical layer security hardly to be deal with. Two One typical situation is considered. One is that the attackers have the ideal CSI and another is eavesdroppers channel are highly correlated to legitimate channel. Our scheme integrates the upper layer with physical layer secure together to gaurantee the security in real communication system. Extensive theoretical analysis and simulations are conducted to demonstrate its effectiveness. The proposed method is feasible to spread in many other communicate scenarios.

Cooperative-Jamming-Aided Secrecy Enhancement in Wireless Networks With Passive Eavesdroppers

This paper investigates cooperative security in wireless networks, where a source (Alice) intends to transmit a confidential message to a legitimate destination (Bob), with the help of a cooperative jammer (Charlie), coexisting with multiple passive eavesdroppers (Eves). In particular, by assuming knowledge of Bobs perfect channel state information (CSI) but only Eves’ statistical CSIs, secrecy beamforming with artificial noise (AN) is utilized for secure transmission, and cooperative jamming (CJ) is explored to further enhance secrecy. We first derive an accurate closed-form expression for the secrecy outage probability (SOP), and establish the condition under which positive secrecy rate is achievable. Then, we provide a secure transmit design for maximizing the SOP constrained secrecy rate. Moreover, based on a strict mathematical analysis, we characterize the impact of the main channel quality and the number of Eves on transmit design and secrecy performance. Specifically, optimal power allocation ratio between the information-bearing signal and the AN signal increases as the main channel quality improves, and decreases with the number of Eves. Numerical results confirm that our design achieves performance improvement in terms of both secrecy rate and secure energy efficiency, as compared to the approach without CJ.

Joint cooperative jamming and beamforming for secure transmission in two-cell networks

In this paper, we consider secure downlink transmission in two-cell networks where the one base station (Alice) provides secure wireless services to its legitimate receiver (Bob) in the presence of a passive eavesdropper (Eve). For multi-cell networks, the inter-cell interference to Bob and Eve has a great impact on the security performance. In order to improve the confidentiality of information transfer from Alice to Bob, it is crucial to properly design the transmit strategies. With the results of conventional cooperative jamming (CJ) scheme, we propose a modified CJ scheme for cooperative base station (CBS) to further degrade the quality of signal reception at Eve, and therefore the secrecy rate can be increased. Both theoretical analysis and numerical results show that the modified CJ scheme outperforms the conventional CJ scheme by achieving a higher secrecy rate. Additionally, by taking the energy efficiency into account, we formulate an adaptive cooperation, in which the CBS is allowed to provide services to its desired receiver. We design a cooperative beamforming for CBS to satisfy the rate requirement while maximizing the secrecy rate of legitimate channel. Numerical results validate the effectiveness of the proposed cooperation scheme.

Simple and Robust Near-Optimal Single Differential Detection Scheme for IEEE 802.15.4 BPSK Receivers

In this study, the authors propose a simple and robust near-optimal single differential coherent detection scheme for IEEE 802.15.4 binary phase shift keying (BPSK) receivers. The detection process is initiated by a bootstrap processor, which is responsible for estimating and compensating the residual carrier frequency offset effect in the sample from the autocorrelator output. In particular, for this bootstrap processor, a simple estimator with only one addition operation is provided. This low complexity benefits from that the high signal-to-noise ratio and a trigonometric approximation are combined, i.e. sin − 1 ( x ) ≃ x , for simplification of the full estimation scheme. Further, to achieve near optimal performance as well as robustness to carrier frequency offset, the observation space is subdivided into four equi-angular regions to decrease the estimation error introduced by the involved approximation. The proposed method is validated through detailed physical layer (PHY) simulations according to the IEEE 802.15.4 standard. The simulation results demonstrate that, compared with the full estimator, the proposed algorithm can acquire a fairly accurate estimation, with almost no loss of reliability and robustness, whereas complexity reduction is also achieved.

Build-in wiretap channel I with feedback and LDPC codes by soft decision decoding

Many approaches to build a wiretap channel (WTC) by multi-input multi-output system have been introduced. Different from those approaches, the authors propose a feedback method combined with the low-density parity-check (LDPC) codes for building the WTC I (WTC-I) to achieve unconditional security under single-input single-output system by the soft decision decoding. The novel approach establishes the WTC-I on both the binary symmetric channel and binary input additive white Gaussian noise channel. In order to keep the eavesdropper be fully ignorant about the secret information, randomness is added to the feedback signals from the destination by taking advantage of feedback. In addition, the message to be sent is encoded by the LDPC codes such that it can be correctly decoded by a legitimate receiver. Furthermore, the secret information transmission capacity can be improved by the soft decision decoding.