Byzantine Attack and Defense in Cognitive Radio Networks: A Survey

The Byzantine attack in cooperative spectrum sensing (CSS), also known as the spectrum sensing data falsification (SSDF) attack in the literature, is one of the key adversaries to the success of cognitive radio networks (CRNs). In the past couple of years, the research on the Byzantine attack and defense strategies has gained worldwide increasing attention. In this paper, we provide a comprehensive survey and tutorial on the recent advances in the Byzantine attack and defense for CSS in CRNs. Specifically, we first briefly present the preliminaries of CSS for general readers, including signal detection techniques, hypothesis testing, and data fusion. Second, we analyze the spear and shield relation between Byzantine attack and defense from three aspects: the vulnerability of CSS to attack, the obstacles in CSS to defense, and the games between attack and defense. Then, we propose a taxonomy of the existing Byzantine attack behaviors and elaborate on the corresponding attack parameters, which determine where, who, how, and when to launch attacks. Next, from the perspectives of homogeneous or heterogeneous scenarios, we classify the existing defense algorithms, and provide an in-depth tutorial on the state-of-the-art Byzantine defense schemes, commonly known as robust or secure CSS in the literature. Furthermore, we highlight the unsolved research challenges and depict the future research directions.Comment: Accepted by IEEE Communications Surveys and Tutoiral

Varieties of onset: onset and conflict dynamics in civil war

How do civil wars begin? And does the type of onset impact how conflicts unfold? While the study of why civil wars start has been a central focus in the literature on civil war, the study of how civil wars start has received limited attention so far. In this thesis, I contribute to this scholarship with a novel conceptualisation of civil war onset as a varied political event. I argue that different types of onset represent different forms of political challenge to state sovereignty and, as such, set countries in distinct conflict trajectories. Theoretically, I propose a novel typology to account for the variation across onsets. I identify four ideal-typical forms of civil war onset: peripheral challenge, state disintegration, coup, and insurrectionary protests. I then build on this original typology and develop a path-dependent explanation for several macro-level wartime dynamics, including warfare, intensity, and conflict duration, that originate in the form of onset. In that sense, the types of civil war onset reflect different initial conditions that set conflicts onto patterned trajectories. Given how civil wars begin, I expect that some conflicts will be more likely to be fought through symmetric modes of warfare, some will be more severe, or last longer than others. Empirically, I build a novel dataset of civil war, DatOnset, that accounts for the variation in the form of onset in all civil wars between 1944 and 2020, and validate the proposed classification through an extensive expert survey. Next, I use the typology of civil war onset empirically in two complementary ways. First, I replicate several landmark studies of the causes of civil war and provide evidence that the correlates of onset that we know about are clustered by types of onset. Second, to test my theory of civil war trajectories, I conduct cross- national regression analysis using the typology of onset as the main independent variable. I find clear empirical patterns in how civil wars unfold, which originate in the form of conflict onset. Lastly, I complement the cross-national findings with original archival material from Burundi’s civil war (1993-2006) to describe in depth the dynamics at play during onset in the form of state disintegration. I demonstrate that state disintegration onsets occur in highly fragmented political landscapes, paired with weak institutions, and the existence of private militias mobilised by political elites. Overall, the thesis makes several important contributions. Among these, distinguishing between civil wars based on the type of onset provides clear scope conditions and insightful case selection strategies, which is essential for robust comparative analyses of civil wars

Even eating you can bite your tongue: dynamics and challenges of the Juba peace talks with the Lord’s Resistance Army

RUNNER-UP for the Cedric Smith Prize 2014, a prize for the best piece of peace and conflict research awarded by the Conflict Research Society. NOMINATED for Peace Science Society's 2014 Walter Isard Award for the Best Dissertation in Peace Science. This thesis offers an alternative narrative why the Juba Peace Talks between the Government of Uganda and the rebel Lord’s Resistance Army (LRA) and its political wing, the Lord’s Resistance Movement (LRM), did not produce a Final Peace Agreement. Widely considered the most promising peace effort in the history of a violent conflict that began in 1986, talks were mediated by the Government of Southern Sudan from 2006 to 2008. During this time, the parties signed five separate agreements on a range of issues, yet in 2008 the LRA’s leader, Joseph Kony, failed to endorse them through a final signature. An aerial attack on the LRA by the Ugandan army spelled the end of the Juba Talks. It is commonly argued that as the first peace talks conducted with people wanted by the International Criminal Court, the Juba Talks collapsed because the arrest warrants made a negotiated agreement impossible. Another widely accepted reason is that the LRA/M were not committed to peace. This thesis, however, argues that how the LRA/M experienced the muddled and convoluted peace talks was the crucial factor because the dynamics of the process confirmed existing power dynamics. Internally, the LRA/M’s dynamics were profoundly influenced by their perception of being trapped in an established hostile system, causing a struggle to transform their own dynamics constructively. Offering an analytical chronology of the Juba Talks with an empirical emphasis on the perspective of the LRA/M and an analysis of LRA/M structures and behavioural patterns that emerged in the process, this thesis further outlines that judging success or failure of a peace process on whether agreements have been signed is misplaced. Despite not producing a final agreement, the Juba Talks contributed to peace and change in Uganda