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We report results of an experiment in applying deep Q-learning for dynamic spectrum sharing (DSS) in the Alleys of Austin scenario from the DARPA Spectrum Collaboration Challenge. This scenario mimics mobile operations in an urban environment by up to five squads (teams) of soldiers. Each team operates its own wireless network. We consider teamwise– distributed DSS, where there is no central agent to coordinate spectrum usage across teams, but spectrum usage within each team is coordinated by a single member of that team. The spatial distributions of the soldiers creates opportunities for spatial reuse by certain subsets of the teams, and our experiment is set up to evaluate whether the deep Q-learning algorithm can discover and take advantage of these opportunities. The results show that deep Q-learning is able to take advantage of spatial reuse and that doing so results in better performance than a fair-share, disjoint spectrum allocation among the teams. 

An algorithm to identify the bottleneck nodes linking two component networks in a simple network of networks (NoN) configuration is proposed. The proposed bottleneck identification algorithm is based on applying a support vector machine on clustered packet delay measurements. This algorithm has the advantage that it requires almost no information about the topology of the underlying NoN. Simulation results show that this algorithm can provide very good detection performance when the component networks of the NoN are not too small in size, or when the connectivity between nodes within the component networks is not too sparse. 

We consider the problem of jammer placement to partition a wireless network, where the network nodes and jammers are located in the real plane. In previous research, we found optimal and suboptimal jammer placements by reducing the search space for the jammers to the locations of the network nodes. In this paper, we develop techniques to find optimal jammer placements over all possible jammer placements in the real plane. Our approach finds a set of candidate jammer locations (CJLs) such that a jammer-placement solution using the CJLs achieves the minimum possible cardinality among all possible jammer placements in the real plane. The CJLs can be used directly with the optimal and fast, suboptimal algorithms for jammer placement from our previous work. 

Wireless communications networks are often mod- eled as graphs in which the vertices represent wireless devices and the edges represent the communication links between them. However, graphs fail to capture the time-varying nature of wire- less networks. Temporal networks are graphs in which the sets of nodes or edges are time-varying. We consider the most common case, in which the set of nodes is fixed but the presence of edges changes over time. Most previous work on analyzing temporal networks has focused on summary measures that combine the contributions of different paths by using different weights for paths with different delays. Such summary measures are efficient to compute but may lose valuable information about the temporal behavior of the network. We propose techniques that characterize the delays of all paths between nodes in temporal networks. We then apply these techniques to identify dominant patterns in the temporal paths connecting nodes. Example temporal networks are used to illustrate these phenomena, and we consider implications to wireless networks. 

Wireless communication systems are susceptible to both unintentional interference and intentional jamming attacks. For mesh and ad-hoc networks, interference affects the network topology and can cause the network to partition, which may completely disrupt the applications or missions that depend on the network. Defensive techniques can be applied to try to prevent such disruptions to the network topology. Most previous research in this area is on improving network resilience by adapting the network topology when a jamming attack occurs. In this paper, we consider making a network more robust to jamming attacks before any such attack has happened. We consider a network in which the positions of most of the radios in the network are not under the control of the network operator, but the network operator can position a few “helper nodes” to add robustness against jamming. For instance, most of the nodes are radios on vehicles participating in a mission, and the helper nodes are mounted on mobile robots or UAVs. We develop techniques to determine where to position the helper nodes to maximize the robustness of the network to certain jamming attacks aimed at disrupting the network topology. Using our recent results for quickly determining how to attack a network, we use the harmony search algorithm to find helper node placements that maximize the number of jammers needed to disrupt the network 

Cooperative spectrum sensing is often necessary in cognitive radios systems to localize a transmitter by fusing the measurements from multiple sensing radios. However, revealing spectrum sensing information also generally leaks information about the location of the radio that made those measurements. We propose a protocol for performing cooperative spectrum sensing while preserving the privacy of the sensing radios. In this protocol, radios fuse sensing information through a distributed particle filter based on a tree structure. All sensing information is encrypted using public-key cryptography, and one of the radios serves as an anonymizer, whose role is to break the connection between the sensing radios and the public keys they use. We consider a semi-honest (honest-but-curious) adversary model in which there is at most a single adversary that is internal to the sensing network and complies with the specified protocol but wishes to determine information about the other participants. Under this scenario, an adversary may learn the sensing information of some of the radios, but it does not have any way to tie that information to a particular radio’s identity. We test the performance of our proposed distributed, tree-based particle filter using physical measurements of FM broadcast stations.