A Survey on Wireless Security: Technical Challenges, Recent Advances and Future Trends

This paper examines the security vulnerabilities and threats imposed by the inherent open nature of wireless communications and to devise efficient defense mechanisms for improving the wireless network security. We first summarize the security requirements of wireless networks, including their authenticity, confidentiality, integrity and availability issues. Next, a comprehensive overview of security attacks encountered in wireless networks is presented in view of the network protocol architecture, where the potential security threats are discussed at each protocol layer. We also provide a survey of the existing security protocols and algorithms that are adopted in the existing wireless network standards, such as the Bluetooth, Wi-Fi, WiMAX, and the long-term evolution (LTE) systems. Then, we discuss the state-of-the-art in physical-layer security, which is an emerging technique of securing the open communications environment against eavesdropping attacks at the physical layer. We also introduce the family of various jamming attacks and their counter-measures, including the constant jammer, intermittent jammer, reactive jammer, adaptive jammer and intelligent jammer. Additionally, we discuss the integration of physical-layer security into existing authentication and cryptography mechanisms for further securing wireless networks. Finally, some technical challenges which remain unresolved at the time of writing are summarized and the future trends in wireless security are discussed.Comment: 36 pages. Accepted to Appear in Proceedings of the IEEE, 201

Application of Expectation-Maximization Algorithm to the Detection of Direct-Sequence Signal in Pulsed Noise Jamming

We consider the detection of direct-sequence spread spectrum signal received in pulsed noise jamming enviromment. The Expectation- Maximization Algorithm is used to estimate the unknown jammer parameters and hence obtain a decision on the binary signal based on the estimated IikeIihood functions. The probability of eerror performance of the algorithm is simulated for a repeat code and a (7,4) block code. Simulation results show that at low signal to thermal noise ratio and high jammer power, the EM detector performs significantly better than the hard limiter and somewhat better than the soft limiter. Also, at low SNR, there is little degradauon as compared to the maximum-likelihood detector with true jammer parameters. At high SNR, the soft limiter outperforms the EM detector

Space-time coding for CDMA-based wireless communication systems

Thesis (Master)--Izmir Institute of Technology, Electronics and Communication Engineering, Izmir, 2002Includes bibliographical references (leaves: 72-75)Text in English; Abstract: Turkish and Englishx, 75 leavesMultiple transmit antennas giving rise to diversity (transmit diversity) have been shown to increase downlink (base station to the mobile) capacity in cellular systems.The third generation partnership project (3GPP) for WCDMA has chosen space time transmit diversity (STTD) as the open loop transmit diversity technique for two transmit antennas.On the other hand, the CDMA 2000 has chosen space time spreading (STS) and orthogonal transmit diversity (OTD) as the open loop transmit diversity.In addition to all the standardization aspects, proposed contributions such as space time coding assisted double spread rake receiver (STC-DS-RR) are exist.In this thesis, open loop transmit diversity techniques of 3GPP, CDMA 2000 and existing contributions are investigated.Their performances are compared as a means of biterror- rate (BER) versus signal-to-noise ratio (SNR)

Performance Study of Hybrid Spread Spectrum Techniques

This thesis focuses on the performance analysis of hybrid direct sequence/slow frequency hopping (DS/SFH) and hybrid direct sequence/fast frequency hopping (DS/FFH) systems under multi-user interference and Rayleigh fading. First, we analyze the performance of direct sequence spread spectrum (DSSS), slow frequency hopping (SFH) and fast frequency hopping (FFH) systems for varying processing gains under interference environment assuming equal bandwidth constraint with Binary Phase Shift Keying (BPSK) modulation and synchronous system. After thorough literature survey, we show that hybrid DS/FFH systems outperform both SFH and hybrid DS/SFH systems under Rayleigh fading and multi-user interference. Also, both hybrid DS/SFH and hybrid DS/FFH show performance improvement with increasing spreading factor and decreasing number of hopping frequencies

Application of Expectation-Maximization Algorithm to the Detection of a Direct-Sequence Signal in Pulsed Noise Jamming

We consider the detection of a direct-sequence spread-spectrum signal received in a pulsed noise jamming environment. The expectation-maximization algorithm is used to estimate the unknown jammer parameters and hence obtain a decision on the binary signal based on the estimated likelihood functions. The probability of error performance of the algorithm is simulated for a repeat code and a (7,4) block code. Simulation results show that at low signal-to-thermal noise ratio and high jammer power, the EM detector performs significantly better than the hard limiter and somewhat better than the soft limiter. Also, at low SNR, there is little degradation as compared to the maximum-likelihood detector with true jammer parameters. At high SNR, the soft limiter outperforms the EM detector

Orthogonal multicarrier modulation for high-rates mobile and wireless communications

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN037085 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Effects of Cyclic Prefix Jamming Versus Noise Jamming in OFDM Signals

Signal jamming of an orthogonal frequency-division multiplexing (OFDM) signal is simulated in MATLAB. Two different means of jamming are used to see, which is a more efficient way to disrupt a signal using the same signal power. The first way is a basic additive white Gaussian noise (AWGN) jammer that equally jams the entire signal. The second way is an AWGN jammer that targets only the cyclic prefix (CP) of the signal. These two methods of jamming are simulated using different channel models and unknowns to get varying results. The three channel models used in the simulations are the no channel case, the simple multipath case, and the fading multipath case. The general trend shows that as the channel model becomes more complex, the difference in the effectiveness of each jamming technique becomes less. The unknown in this research is the symbol-time delay. Since OFDM signals are characterized by multipath reception, the signal arrives at a symbol-time delay which is known or unknown to the jamming signal and the receiver. Realistically, the symbol-time delay is unknown to each and in that case, a Maximum Likelihood (ML) Estimator is used to find the estimated symbol-time delay. This research simulates the symbol-time delay as a known and an unknown at the jammer and receiver. The general trend shows that jamming the cyclic prefix is more effective than noise jamming when the symbol-time delay is unknown to the receiver

Wavelet-based multi-carrier code division multiple access systems

EThOS - Electronic Theses Online ServiceGBUnited Kingdo