Context-aware Opportunistic Routing in Mobile Ad-hoc Networks Incorporating Node Mobility

Opportunistic routing (OR) employs a list of candi- dates to improve reliability of wireless transmission. However, list-based OR features restrict the freedom of opportunism, since only the listed nodes can compete for packet forwarding. Additionally, the list is statically generated based on a single metric prior to data transmission, which is not appropriate for mobile ad-hoc networks. This paper provides a thorough perfor- mance evaluation of a new protocol - Context-aware Opportunistic Routing (COR). The contributions of COR are threefold. First, it uses various types of context information simultaneously such as link quality, geographic progress, and residual energy of nodes to make routing decisions. Second, it allows all qualified nodes to participate in packet forwarding. Third, it exploits the relative mobility of nodes to further improve performance. Simulation results show that COR can provide efficient routing in mobile environments, and it outperforms existing solutions that solely rely on a single metric by nearly 20 - 40 %.

Space, diffusion and mobility

Given its origins in traditional dialectology, and given advances in our understanding of the social embedding of language variation, it is paradoxical that space should be one of the categories that has received least attention of all in variationist sociolinguistics. Until recently, space has largely been treated as an empty stage on which sociolinguistic processes are enacted. It has been unexamined, untheorized, and its role in shaping and being shaped by variation and change untested. One function of this chapter, therefore, is to assert that space makes a difference, and to begin, in a very hesitant way, to map out what a geographically informed variation analysis might need to address. It also examines variationist interactions with the related concept of mobility. It might be reasonable to think that human geographers would provide some clues on how to proceed. As we will see, they have engaged in a great deal of soul searching about the goals of their discipline, its very existence as a separate field of enquiry, and the directions it should take. Indeed there are remarkable parallels between the recent history of human geographic thought, and interest in language variation across space. Although space has been undertheorized in variation studies, a number of researchers, from the traditional dialectologists through to those interested in the dialectology of mobility and contact, have, of course, been actively engaged in research on geographical variation and language use. Their work will be contextualized here to highlight both the parallels with theory-building in human geography, but also some of the criticisms of earlier approaches which have fed through to human geography, but remain largely unquestioned in variationist practice. The chapter therefore presents a brief theoretical background to space and mobility, before exemplifying these concepts in variationist research through an examination of, for example, the spatial diffusion of linguistic innovations, the spatial configuration of linguistic boundaries and initial steps to examine the consequences of mobility for variationist research.

The role of mundane mobility and contact in dialect death and dialect birth

Urry begins his 2007 book, Mobilities, by throwing some quite stunning statistics at his readers: in 2010, there were one billion legal international arrivals at ports and airports; in 1800 people in the US travelled on average 50 metres per day, today it is 50 kilometres per day; 8.7% of world employment is in tourism; and, at any one time, there are 360,000 passengers in flight above the United States (2007: 3-4). But very many of these mobilities for the individuals concerned are or have become rather unexceptional – a flight to a holiday in Majorca or Florida, a journey on a crowded commuter train into Madrid or Tokyo, a cross-Channel ferry to Calais in France to pick up some cheap wine and a camembert. Whilst much of the theoretically influential dialectological literature on mobility reports on long-distance, often permanent, often dangerous migrations, I turn our attention here to the dialectological consequences of this unexceptional everyday movement. I will argue here that, just as more dramatic and long-distance mobilities can trigger linguistic change, so too can the much more mundane movements we engage in in everyday life. I demonstrate that the linguistic consequences of that contact are similar if not the same – perhaps less dramatic, perhaps involving the convergence of an initially less divergent array of variants – but typologically of the same ilk. And I demonstrate that because these mobilities have been long-term, intensive and ongoing, their consequences on the dialect landscape have been highly significant. Important to remember, however, is that these mobilities are socially stratified and unevenly distributed. As Wolff put it: “the suggestion of free and equal mobility is … a deception, since we don’t all have the same access to the road” (1993: 253).

Transnational Migration and Cross-border Mobility in the Serbian-Hungarian Border Region

The study is aiming to present migrant groups in the Serbian-Hungarian border region which are playing a role in forming transnational migration, ransnational networks and transnational spaces. Transnational migrants are using material, cultural, social and symbolical capital in various forms. The everyday activities of the people as well as their mobility, emotional attachments, and economic relationships have contributed to a transnational region the cross-border contacts in the last century were always present, even in spite of political and historical changes, only their intensity, political charge and tension has been changing. The asymmetries defining the border region has been reflected in different directions, places, time and in different volume. In this specially built and constantly reorganising scope, people who were living their everyday life have tried to use the differences for their benefit, and to improve their possibilities. With their transnational lifestyles and cross-border networks, they substantially contribute to the stability and prosperity of the cross-border region.

A new methodological approach for studying intergenerational mobility with an application to Swiss data

Despite the widespread interest in the topic and a vast international literature, very little is known about the development of intergenerational mobility in Switzerland. Based on a new harmonized database for Switzerland (comprising various surveys such as different waves of the ISSP, EVS, and the ESS), we provide a systematic account of changes in the link between social origin and destination over time (covering birth cohorts from around 1935 to 1980). We analyze effects of parental education and class on own educational achievement and social class for both men and women, using a refined variant of the methodological approach proposed by Jann and Combet (2012). The approach is based on the concept of proportional reduction of error (PRE) and features a number of advantages over more traditional approaches. For example, it provides smooth estimates of changes in social mobility that have a clear interpretation and it can easily incorporate control variables and multiple dimensions of parental characteristics. To evaluate the validity of our approach, we employ the oft-used log-multiplicative layer effect (a.k.a Unidiff) model (Xie 1992, Erikson and Goldthorpe 1992) as a benchmark. Results indicate that our approach performs well and produces qualitatively similar findings as Xie's model. For both men and women, effects of social origin initially decreased, but then, towards the end of the observation period, increased again. This u-shaped pattern, which can be observed with respect to both education and class, appears to be more pronounced for women than for men.

Intergenerational Mobility in Switzerland. A Comparison of Methodological Approaches

Despite the widespread interest in the topic and a vast international literature, only little is known about the development of intergenerational mobility in Switzerland. Based on a new harmonized database for Switzerland (comprising various surveys such as different waves of the ISSP, EVS, or the ESS), we provide a systematic account of changes in the link between social origin and destination over time (covering birth cohorts from 1940 through 1980). We analyze effects of parental education and class on own educational achievement and social class for both men and women, using a refined variant of the methodological approach proposed by Jann and Combet (2012). The approach is based on the concept of proportional reduction of error (PRE) and features a number of advantages over more traditional approaches. For example, it provides smooth estimates of changes in social mobility that have a clear interpretation and it can easily incorporate control variables and multiple dimensions of parental characteristics. To evaluate the validity of our approach, we employ the oft-used log-multiplicative layer effect model (Xie 1992) as a benchmark. Results indicate that our approach performs well and produces qualitatively similar findings as Xie’s model. For men, effects of social origin have been stable over the observed period. For women, however, social mobility significantly decreased among younger cohorts, mostly due to expanding female education and labor force participation. Jann, Ben, Benita Combet (2012). Zur Entwicklung der intergenerationalen Mobilität in der Schweiz (On the Development of Intergenerational Mobility in Switzerland). Swiss Journal of Sociology 38(2): 177-199. Xie, Yu (1992). The Log-Multiplicative Layer Effect Model for Comparing Mobility Tables. American Sociological Review 57(3): 380-395.

Translocal Practices on the Tibetan Plateau: Motorised Mobility of Pastoralists and Spatial Transformations

Tibetan pastoralist communities in Amdo, the north-eastern region of the Tibetan plateau, have undergone tremendous change due to a number of state induced modernisation processes. Road infrastructure is but one development that aims to facilitate transition from subsistence to a market economy and to link remote pastoralist production into the global or regional market. This paper starts from the local perspective and examines how the expansion of road infrastructure and increased ownership of motorised vehicles has impacted on the mobility of pastoralists. It argues that motorisation and the increased availability of roads creates an interface for pastoralists through which they negotiate a newly emerging translocality. Roads are embedded into everyday movements and provide pastoralists with ways to integrate new developments into their lives.