8 research outputs found
Robust Wireless Communication for Multi-Antenna, Multi-Rate, Multi-Carrier Systems
Abstract Today's trend of migrating radio devices from hardware to software provides potential to create flexible applications for both commercial and military use. However, this raises security concerns, as malicious attackers can also be generated easily to break legitimate communications. In this research work, our goal is to design a robust anti-jamming radio framework. We particularly investigate three different aspects of jamming threats: high-power jammers, link attacks on rate adaptation, and jamming in multicarrier systems. The threats of high-power jamming to wireless communications today are realistic due to the ease of access to powerful jamming sources such as the availability of commercial GPS/WiFi/cellular devices on the market, or RF guns built from microwave ovens' magnetron. To counter high-power jamming attacks, we develop SAIM which is a hybrid system capable of resisting jammers of up to 100,000 times higher power than legitimate communication nodes. The system robustness relies on our own antenna structure specially designed for anti-jamming purpose. We develop an efficient algorithm for auto-configuring the antenna adaptively to dynamic environments. We also devise a software-based jamming cancellation technique for appropriately extracting original signals, which is more robust than traditional MIMO approaches, as pilot signals are not required in SAIM. In spite of the robustness of SAIM, our design is more appropriate for malicious environments with powerful jammers, where mechanical steering is feasible, e.g., military applications. Residential and commercial wireless communication systems are still vulnerable to even limited-power jamming, as in today's standard wireless protocols, rate information is exposed to adversaries. Rate-based attacks have been demonstrated to severely degrade the networks at very low cost. To mitigate rate-based attacks, we develop CBM, a system capable of hiding rate and -at the same time -increasing resiliency against jammers up to seven times higher than regular systems, where rate is exposed. We achieve the resiliency boost by generalizing Trellis Coded Modulation to allow non-uniform codeword mapping. We develop an efficient algorithm for finding good non-uniform codes for all modulations in {BPSK, QPSK, 8-PSK, 16-QAM, 64-QAM}. To conceal rate information, we devise an efficient method for generating cryptographic interleaving functions. In recently deployed communication networks such as WiFi and LTE systems, MIMO and OFDM are the two main techniques for increasing bandwidth efficiency. While MIMO increases the channel capacity by spatial processing on multiple received signals, OFDM mitigates impacts of dynamic variations in wide-band channels and allows frequency reuse with overlapping carriers. Synchronization is a key for high-throughput performance in MIMO and OFDM systems. In this work, we study impacts of jamming attacks specifically targeting to control channels in WiFi and LTE networks. Our study focuses on efficient techniques for both jamming and anti-jamming in multicarrier systems
Secure protocols for wireless availability
Since wireless networks share a communication medium, multiple transmissions
on the same channel cause interference to each other and degrade the
channel quality, much as multiple people talking at the same time make for
inefficient meetings. To avoid transmission collision, the network divides
the medium into multiple orthogonal channels (by interleaving the channel
access in frequency or time) and often uses medium access control (MAC)
to coordinate channel use. Alternatively (e.g., when the wireless users use
the same physical channel), the network users can emulate such orthogonal
channel access in processing by spreading and coding the signal. Building
on such orthogonal access technology, this dissertation studies protocols that
support the coexistence of wireless users and ensure wireless availability.
In contrast to other studies focusing on improving the overall e fficiency
of the network, I aim to achieve reliability at all times. Thus, to study the
worst-case misbehavior, I pose the problem within a security framework and
introduce an adversary who compromised the network and has insider access.
In this dissertation, I propose three schemes for wireless availability:
SimpleMAC, Ignore-False-Reservation MAC (IFR-MAC), and Redundancy
O ffset Narrow Spectrum (RONS). SimpleMAC and IFR-MAC build on MAC
protocols that utilize explicit channel coordination in control communication.
SimpleMAC counters MAC-aware adversary that uses the information being
exchanged at the MAC layer to perform a more power e fficient jamming
attack. IFR-MAC nulli ffies the proactive attack of denial-of-service injection
of false reservation control messages. Both SimpleMAC and IFR-MAC
quickly outperform the Nash equilibrium of disabling MAC and converge to
the capacity-optimal performance in worst-case failures. When the MAC
fails to coordinate channel use for orthogonal access or in a single-channel
setting (both cases of which, the attacker knows the exact frequency and time
location of the victim's channel access), RONS introduces a physical-layer, processing-based technique for interference mitigation. RONS is a narrow
spectrum technology that bypasses the spreading cost and eff ectively counters
the attacker's information-theoretically optimal strategy of correlated
jamming
Synoptic analysis techniques for intrusion detection in wireless networks
Current system administrators are missing intrusion alerts hidden by large numbers of false positives. Rather than accumulation more data to identify true alerts, we propose an intrusion detection tool that e?ectively uses select data to provide a picture of ?network health?. Our hypothesis is that by utilizing the data available at both the node and cooperative network levels we can create a synoptic picture of the network providing indications of many intrusions or other network issues. Our major contribution is to provide a revolutionary way to analyze node and network data for patterns, dependence, and e?ects that indicate network issues. We collect node and network data, combine and manipulate it, and tease out information about the state of the network. We present a method based on utilizing the number of packets sent, number of packets received, node reliability, route reliability, and entropy to develop a synoptic picture of the network health in the presence of a sinkhole and a HELLO Flood attacker. This method conserves network throughput and node energy by requiring no additional control messages to be sent between the nodes unless an attacker is suspected. We intend to show that, although the concept of an intrusion detection system is not revolutionary, the method in which we analyze the data for clues about network intrusion and performance is highly innovative