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Abstract: In Vehicle-to-Vehicle (V2V) communications, the relatively large Doppler-spread poses a great thread to the system performance. In this paper, we propose a new physical layer air-link technology, which combines the advantages of CDMA and OFDM technologies. More specifically, we apply the column-wise complementary codes to the original OFDM-based physical layer design, which can effectively mitigate the Doppler effect under high-speed communication scenarios. The superiority of the new architecture is demonstrated by mathematical analysis and extensive computer simulations. The main contribution of this paper is two-fold. First, the presented analysis provides a more deep insight into the key performance bottleneck in the emerging short-range communications (DSRC) technology. Second, the proposed air link architecture can be implemented with a relatively low implementation complexity, which is desirable for practical applications. [Copyright &y& Elsevier]

Abstract: Security is critical for sensor networks used in military, homeland security and other hostile environments. Previous research on sensor network security mainly considers homogeneous sensor networks. Research has shown that homogeneous ad hoc networks have poor performance and scalability. Furthermore, many security schemes designed for homogeneous sensor networks suffer from high communication overhead, computation overhead, and/or high storage requirement. Recently deployed sensor network systems are increasingly following heterogeneous designs. Key management is an essential cryptographic primitive to provide other security operations. In this paper, we present an effective key management scheme that takes advantage of the powerful high-end sensors in heterogeneous sensor networks. The performance evaluation and security analysis show that the key management scheme provides better security with low complexity and significant reduction on storage requirement, compared with existing key management schemes. [Copyright &y& Elsevier]

Abstract: Easy associations with wireless access points (APs) give users temporal and quick access to the Internet. It needs only a few seconds to take their machines to hotspots and do a little configuration in order to have Internet access. However, this portability becomes a double-edged sword for ignorant network users. Network protocol analyzers are typically developed for network performance analysis. Nonetheless, they can also be used to reveal user’s privacy by classifying network traffic. Some characteristics in IEEE 802.11 traffic particularly help identify users. Like actual human fingerprints, there are also unique traffic characteristics for each network user. They are called network user fingerprints, by tracking which more than half of network users can be connected to their traffic even with medium access control (MAC) layer pseudonyms. On the other hand, the concept of network user fingerprint is likely to be a powerful tool for intrusion detection and computer/digital forensics. As with actual criminal investigations, comparison of sampling data to training data may increase confidence in criminal specification. This article focuses on a survey on a user fingerprinting technique of IEEE 802.11 wireless LAN traffic. We also summarize some of the researches on IEEE 802.11 network characteristic analysis to figure out rogue APs and MAC protocol misbehaviors. [Copyright &y& Elsevier]