Performance Evaluation of Distributed-Antenna Communications Systems Using Beam-Hopping

Digital beamforming (DBF) techniques are capable of improving the performance of communications systems significantly. However, if the transmitted signals are conflicted with strong interference, especially, in the direction of the transmitted beams , these directional jamming signals will severely degrade the system performance. In order to efficiently mitigate the interference of the directional jammers, in this contribution a beam-hopping (BH) communications scheme is proposed. In the proposed BH communications scheme, only one pair of the beams is used for transmission and it hops from one to the next according to an assigned BH pattern. In this contribution a range of expressions in terms of the average SINR performance have been derived, when both the uplink and downlink are considered. The average SINR performance of the proposed BH scheme and that of the conventional single-beam (SB) as well as multiple-beam (MB) assisted beam-processing schemes have been investigated. Our analysis and results show that the proposed BH scheme is capable of efficiently combating the directional jamming, with the aid of utilizing the directional gain of the beams generated by both the transmitter and the receiver. Furthermore, the BH scheme is capable of reducing the intercept probability of the communications. Therefore, the proposed BH scheme is suitable for communications, when several distributed antenna arrays are available around a mobile

Hop-Reservation Multiple Access with Variable Slots

AbstractHop-reservation multiple access control protocols in Ad Hoc networks are widely researched for its virtue in anti-jamming. Several typical such protocols are introduced and compared. Based on the analysis about their performance on anti-jamming and ability to serve upper protocols, a hop-reservation multiple access protocol with variable slot (HMAVS) is proposed. By the adaptation of variable length slots, the hop speed of control channel can be supported to the largest extent while diverse applications can be served without additional cost. Simulation results demonstrate the preference of HMAVS to other existing protocols

Enabling Self-healing Smart Grid Through Jamming Resilient Local Controller Switching

A key component of a smart grid is its ability to collect useful information from a power grid for enabling control centers to estimate the current states of the power grid. Such information can be delivered to the control centers via wireless or wired networks. It is envisioned that wireless technology will be widely used for local-area communication subsystems in the smart grid (e.g., in distribution networks). However, various attacks with serious impact can be launched in wireless networks such as channel jamming attacks and denial-of-service attacks. In particular, jamming attacks can cause significant damages to power grids, e.g., delayed delivery of time-critical messages can prevent control centers from properly controlling the outputs of generators to match load demands. In this paper, a communication subsystem with enhanced self-healing capability in the presence of jamming is designed via intelligent local controller switching while integrating a retransmission mechanism. The proposed framework allows sufficient readings from smart meters to be continuously collected by various local controllers to estimate the states of a power grid under various attack scenarios. The jamming probability is also analyzed considering the impact of jammer power and shadowing effects. In addition, guidelines on optimal placement of local controllers to ensure effective switching of smart meters under jamming are provided. Via theoretical, experimental and simulation studies, it is demonstrated that our proposed system is effective in maintaining communications between smart meters and local controllers even when multiple jammers are present in the network

Wireless security for secure facilities

This thesis presents methods for securing a facility that has wireless connectivity. The goal of this research is to develop a solution to securing a facility that utilizes wireless communications. The research will introduce methods to track and locate the position of attackers. This research also introduces the idea of using a Honeynet system for added security. This research uses what is called Defense-In-Depth. Defense-in-depth is when multiple layers of security are used. The first of the layers is the Zone of Interference. This Zone is an area where jammer transmitters and directive antennas are set up to take advantage of the near-far-effect. The idea is to use the near-far-effect to give a stronger signal on the perimeter of the secure area, to mask any signals escaping from the secure area. This Zone uses directive Yagi antenna arrays to direct the radiation. There are multiple jamming methods that are utilized within this Zone. The next layer of security is the Honeynet Zone. The idea is to make an attacker believe that they are seeing real network traffic. This is done at the Honeynet Zone once a device has been determined to be unfriendly. Decoy mobile devices are first placed within the Honeynet Zone. Spoofed traffic is then created between the Honeynet base stations and the decoy mobile devices zone; using adaptive antennas incorporated within the design to face the signals away from the inside secure area. The third defense is position location and tracking. The idea is to have constant tracking of all devices in the area. There are several methods available to locate and track a device that is giving off an RF signal. This thesis looks at combining all these methods into an integrated, and more robust, facility security system

A Game of One/Two Strategic Friendly Jammers Versus a Malicious Strategic Node

We present a game-theoretic analysis of the interaction between a malicious node, attempting to perform unauthorized radio transmission, and friendly jammers trying to disrupt the malicious communications. We investigate the strategic behavior of the jammers against a rational malicious node and highlight counterintuitive results for this conflict. We also analyze the impact of multiple friendly jammers sharing the same goal but acting without coordination; we find out that this scenario offers a better payoff for the jammers, which has some strong implications on how to implement friendly jamming