Management and routing algorithms for ad-hoc and sensor networks

Large scale wireless adhoc networks of computers, sensors, PDAs etc. (i.e. nodes) are revolutionizing connectivity and leading to a paradigm shift from centralized systems to highly distributed and dynamic environments. An example of adhoc networks are sensor networks, which are usually composed by small units able to sense and transmit to a sink elementary data which are successively processed by an external machine. Recent improvements in the memory and computational power of sensors, together with the reduction of energy consumptions, are rapidly changing the potential of such systems, moving the attention towards datacentric sensor networks. A plethora of routing and data management algorithms have been proposed for the network path discovery ranging from broadcasting/floodingbased approaches to those using global positioning systems (GPS). We studied WGrid, a novel decentralized infrastructure that organizes wireless devices in an adhoc manner, where each node has one or more virtual coordinates through which both message routing and data management occur without reliance on either flooding/broadcasting operations or GPS. The resulting adhoc network does not suffer from the deadend problem, which happens in geographicbased routing when a node is unable to locate a neighbor closer to the destination than itself. WGrid allow multidimensional data management capability since nodes' virtual coordinates can act as a distributed database without needing neither special implementation or reorganization. Any kind of data (both single and multidimensional) can be distributed, stored and managed. We will show how a location service can be easily implemented so that any search is reduced to a simple query, like for any other data type. WGrid has then been extended by adopting a replication methodology. We called the resulting algorithm WRGrid. Just like WGrid, WRGrid acts as a distributed database without needing neither special implementation nor reorganization and any kind of data can be distributed, stored and managed. We have evaluated the benefits of replication on data management, finding out, from experimental results, that it can halve the average number of hops in the network. The direct consequence of this fact are a significant improvement on energy consumption and a workload balancing among sensors (number of messages routed by each node). Finally, thanks to the replications, whose number can be arbitrarily chosen, the resulting sensor network can face sensors disconnections/connections, due to failures of sensors, without data loss. Another extension to {WGrid} is {W*Grid} which extends it by strongly improving network recovery performance from link and/or device failures that may happen due to crashes or battery exhaustion of devices or to temporary obstacles. W*Grid guarantees, by construction, at least two disjoint paths between each couple of nodes. This implies that the recovery in W*Grid occurs without broadcasting transmissions and guaranteeing robustness while drastically reducing the energy consumption. An extensive number of simulations shows the efficiency, robustness and traffic road of resulting networks under several scenarios of device density and of number of coordinates. Performance analysis have been compared to existent algorithms in order to validate the results.

Building Peace and/or Gender Equality. Changing Attitudes around Peace, Development and Security in International Cooperation in Rwanda.

The times following international or civil conflicts but also violent revolutions often come with unequal share of the peace dividend for men and women. Delusions for women who gained freedom of movement and of roles during conflict but had to step back during reconstruction and peace have been recorded in all regions of the world. The emergence of peacebuilding as a modality for the international community to ensure peace and security has slowly incorporated gender sensitivity at the level of legal and policy instruments. Focusing on Rwanda, a country that has obtained significant gender advancement in the years after the genocide while also obtaining to not relapse into conflict, this research explores to what extent the international community has contributed to this transformation. From a review of evaluations, findings are that many of the interventions did not purse gender equality, and overall the majority understood gender and designed actions is a quite superficial way which would hardly account for the significative advancement in combating gender discrimination that the Government, for its inner political will, is conducting. Then, after a critique from a feminist standpoint to the concept of human security, departing from the assumption (sustained by the Governemnt of Rwanda as well) that domestic violence is a variable influencing level of security relevant at the national level, a review of available secondary data on GBV is conducted an trends over the years analysed. The emerging trends signal a steep increase in prevalence of GBV and in domestic violence in particular. Although no conclusive interpretation can be formulated on these data, there are elements suggesting the increase might be due to augmented reporting. The research concludes outlining possible further research pathways to better understand the link in Rwanda between the changing gender norms and the GBV.