Towards new methods for mobility data gathering: content, sources, incentives

Over the past decade, huge amounts of work has been done in mobile and opportunistic networking research. Unfortunately, much of this has had little impact as the results have not been applicable to reality, due to incorrect assumptions and models used in the design and evaluation of the systems. In this paper, we outline some of the problems of the assumptions of early research in the field, and provide a survey of some initial work that has started to take place to alleviate this through more realistic modelling and measurements of real systems. We do note that there is still much work to be done in this area, and then go on to identify some important properties of the network that must be studied further. We identify the types of data that are important to measure, and also give some guidelines on finding existing and potentially new sources for such data and incentivizing the holders of the data to share it

The Quest for a Killer App for Opportunistic and Delay Tolerant Networks (Invited Paper)

Delay Tolerant Networking (DTN) has attracted a lot of attention from the research community in recent years. Much work have been done regarding network architectures and algorithms for routing and forwarding in such networks. At the same time as many show enthusiasm for this exciting new research area there are also many sceptics, who question the usefulness of research in this area. In the past, we have seen other research areas become over-hyped and later die out as there was no killer app for them that made them useful in real scenarios. Real deployments of DTN systems have so far mostly been limited to a few niche scenarios, where they have been done as proof-of-concept field tests in research projects. In this paper, we embark upon a quest to find out what characterizes a potential killer applications for DTNs. Are there applications and situations where DTNs provide services that could not be achieved otherwise, or have potential to do it in a better way than other techniques? Further, we highlight some of the main challenges that needs to be solved to realize these applications and make DTNs a part of the mainstream network landscape

Swarm-based Intelligent Routing (SIR) - a new approach for efficient routing in content centric delay tolerant networks

This paper introduces Swarm-based Intelligent Routing (SIR), a swarm intelligence based approach used for routing content in content centric Pocket Switched Networks. We first formalize the notion of optimal path in DTN, then introduce a swarm intelligence based routing protocol adapted to content centric DTN that use a publish/subscribe communication paradigm. The protocol works in a fully decentralized way in which nodes do not have any knowledge about the global topology. Nodes, via opportunistic contacts, update utility functions which synthesizes their spatio-temporal proximity from the content subscribers. This individual behavior applied by each node leads to the collective formation of gradient fields between content subscribers and content providers. Therefore, content routing simply sums up to follow the steepest slope along these gradient fields to reach subscribers who are located at the minima of the field. Via real traces analysis and simulation, we demonstrate the existence and relevance of such gradient field and show routing performance improvements when compared to classical routing protocols previously defined for information routing in DTN

Delay Tolerant Networking over the Metropolitan Public Transportation

We discuss MDTN: a delay tolerant application platform built on top of the Public Transportation System (PTS) and able to provide service access while exploiting opportunistic connectivity. Our solution adopts a carrier-based approach where buses act as data collectors for user requests requiring Internet access. Simulations based on real maps and PTS routes with state-of-the-art routing protocols demonstrate that MDTN represents a viable solution for elastic nonreal-time service delivery. Nevertheless, performance indexes of the considered routing policies show that there is no golden rule for optimal performance and a tailored routing strategy is required for each specific case

Wireless Communications in the Era of Big Data

The rapidly growing wave of wireless data service is pushing against the boundary of our communication network's processing power. The pervasive and exponentially increasing data traffic present imminent challenges to all the aspects of the wireless system design, such as spectrum efficiency, computing capabilities and fronthaul/backhaul link capacity. In this article, we discuss the challenges and opportunities in the design of scalable wireless systems to embrace such a "bigdata" era. On one hand, we review the state-of-the-art networking architectures and signal processing techniques adaptable for managing the bigdata traffic in wireless networks. On the other hand, instead of viewing mobile bigdata as a unwanted burden, we introduce methods to capitalize from the vast data traffic, for building a bigdata-aware wireless network with better wireless service quality and new mobile applications. We highlight several promising future research directions for wireless communications in the mobile bigdata era.Comment: This article is accepted and to appear in IEEE Communications Magazin

No. 24: Spaces of Vulnerability: Migration and HIV/AIDS in South Africa

Seventy per cent of the 36 million people infected worldwide with HIV live in Sub-Saharan Africa and within this region the countries of Southern Africa are the worst affected. The eight countries with the highest rates of infection are in Southern Africa, followed by six countries in East Africa, and then five other countries, only one outside Africa. The reasons why the highest rates of infection in the world occur in Southern Africa are unclear. Although the countries of the region have much in common, their histories over the last twenty years have been very different. A number of different factors have been advanced to explain the general picture of HIV/AIDS in South Africa including its rapid spread, high prevalence and uneven distribution. They include poverty and economic marginalization; differing strains of HIV; high rates of sexually transmitted disease and other opportunistic infection; sexual networking and patterns of sexual contact; the presence or absence of male circumcision; and the role of core-groups such as commercial sex workers. These factors are discussed in greater detail in the paper, reviewing the current state of knowledge about each in South Africa. The paper argues that a key neglected factor in explaining the rapid spread and prevalence of HIV/AIDS in Southern Africa over the last decade is human mobility. The paper therefore examines what is currently known about the connections between migration and HIV/AIDS. Although both migration and HIV have been examined separately in South Africa, we are still far from understanding in detail just how and to what extent migration affects the spread of HIV. Part of the reason for this is that studies of migration and disease tend to concentrate on the urban, or ‘receiving’ areas with little attention being paid to people living in the rural or ‘sending’ areas. Furthermore, there have been very few well-designed epidemiological studies documenting the relationship between migration and infectious diseases. Even more importantly, at this late stage of the Southern African HIV epidemic, there have been few intervention programmes, even on a small scale, which attempt to reduce transmission among migrants and their rural or urban partners. Without a proper understanding of the social, behavioural and psychological consequences of migration, it will not be possible to understand the consequences of migration for the spread of HIV and the particular vulnerability to infection of mobile populations. To effect this conceptual refocus on the social (and sexual) disruption that accompanies migration and mobility, a number of reorientations are required, including: A more detailed understanding of the complex and changing patterns of migrancy in its different forms; Appreciation of the particular vulnerabilities of migrants as migrants (and those with whom they interact) and hence the economic, social, sexual and gender regimes associated with migrancy; Since generic HIV/AIDS interventions seem to be having so little impact in migrant settings and situations of high mobility, there is a need to develop models of intervention that are sensitive to the circumstances of mobile people; As attention is increasingly directed towards models of care and the development of appropriate ‘toolkits’, there is a need to develop interventions appropriate to the situation of migrants and their divided households. The paper argues that none of these objectives can be adequately reached without attention to both the macro- and micro-geographies of mobility, social connectivity and sexual behaviour. The connections between migrancy and HIV/AIDS are more difficult to unravel because HIV/AIDS arrived in the region at a time when population mobility and systems of migrant labour were undergoing considerable change. Migrancy is, by its very nature, highly dynamic and has changed dramatically in scope, scale and diversity over the last two decades. Today it is much more difficult to map the prevalence and spread of disease onto spatial patterns of migration than it was in the past. Several important migration changes that coincided with the advent of HIV/AIDS need to be mentioned: The collapse of apartheid brought new opportunities and reasons for migration across borders within the region. Migrants from neighbouring countries and further afield see South Africa as a new place to trade, shop, seek essential services, work and seek asylum. South Africa’s formal trade with the rest of the continent has exploded, goods carried in the main by long-distance truckers. Informal sector cross-border trading has also expanded dramatically since the end of apartheid. Significant growth in levels of urbanization in South African cities. One consequence has been the displacement of the rural poor to the towns. The new gendering of migrancy. Women are becoming considerably more mobile, migrating for formal and informal work in ever-growing numbers and travelling more frequently for a variety of social and other reasons. The mining industry persists with its regional single-sex contract labour system but there are much higher levels of social contact between migrants miners and people living near the mines. The vulnerabilities to HIV of people (migrant and non-migrant, mobile and relatively immobile) associated with this changing regime of migrancy are poorly understood. The evidence seems to suggest that migrants and migrant households in town and countryside are particularly at risk. So too are the residents of non-migrant communities with whom migrant workers interact on a daily basis. After discussing the general evidence on the causal connections between HIV/AIDS and migration in South Africa, this paper seeks to move the South African debate from the macro- to the micro-scale. By reviewing the findings of research in three different settings the complexity of the connections between migration and HIV/AIDS begins to emerge. The case study areas are spaces of vulnerability, places in which to observe why migrants and those with whom they come into contact are highly susceptible to HIV infection, and hence to develop approaches to decreasing this vulnerability. If workable interventions, based on a sound understanding of local regimes of migration and sexuality, can be developed in disparate case studies such as these, then such best-practice models could have much wider relevance for resisting the ravages of the epidemic. Much can still be done to reduce the impact and the spread of HIV in South Africa. Mother-to-child transmission could be substantially reduced using standard drug regimens. Control of curable STIs would reduce transmission of HIV. The effective promotion of condoms and a reduction in high risk sexual behaviour would have an effect in the longer term. Tuberculosis prophylaxis could substantially reduce tuberculosis morbidity and mortality among those with HIV and this is particularly important in the context of gold mining. The public health implications of the provision of free anti-retroviral therapy to people who are HIV-positive need to be examined. And adequate resources must go to the development of a vaccine for HIV subtype C. None of these interventions are likely to be effective without a sound understanding of the reasons why Southern Africa is the worst affected region in the world, why the epidemic has spread in this region more rapidly than in any other, and why there are such great differences in the infection rates in different provinces, between men and women and critically between migrants and non-migrants. In addition, in all of these interventions special attention should be given to people at high risk of infection, which includes not only commercial sex workers, but also migrants and the partners of migrants. In this context, effort needs to go into the development of epidemiological models to understand the current state and the likely future course of the epidemic, to provide a context for planning and designing interventions, and to evaluate the effectiveness of such interventions. This paper highlights the current state of knowledge about the linkages between HIV/AIDS and migration but it is abundantly clear that there are large gaps in our knowledge of the extent to which migration, and the particular forms of migration that are found in Southern Africa, can explain why the levels of infection in this region are so much higher than anywhere else in the world. Areas in which more work is urgently needed include: Research on the dimensions and social and health impacts of cross-border and internal migration. To what extent does migration contribute to the overall spread of HIV and other STIs? What steps are being taken to ensure that all migrants, legal as well as undocumented, can readily access the treatment services for STIs and HIV prevention programmes? The economic consequences of out-migration from labour-sending areas have been studied in some depth. But what are the consequences of such migration for the sexual health of those who are left behind? As migrants return home with HIV, suffering from other opportunistic infections and soon to develop AIDS, what are the economic implications for their families and communities who will not only lose a bread winner but must also find the resources to provide some level of care for the dying men and women? As the gold mines, in particular, retrench more men and as the economy slows down and unemployment increases, there are indications that more and more women are migrating in search of work. Because of the highly discriminatory labour market, some will have no choice but to engage in commercial sex work. All are likely to be at increased risk of HIV. What kinds of public health interventions can be developed to assist women at such high risk? While it is certain that migration has fuelled the epidemic of HIV in Southern Africa, infections are now so widespread that it seems likely that migration is no longer driving the epidemic. However, programmes to control the epidemic will certainly be considerably less effective if migrant workers continue to spread infections. Programmes aimed at supporting migrants should be given the highest priority but much more work is needed to provide an understanding of the social, behavioural and sexual context of the lives of migrants Perhaps, most importantly, policy issues need to be addressed including the nature and extent of migration, the rights of migrant workers, and the kinds of services to which they have access. This must be done both for those in the formal and in the informal sector and even undocumented migrants must be able to access health services without fear of exposure. The epidemic of HIV/AIDS threatens to devastate much of Southern Africa. Dealing with the epidemic must be given the highest priority and treated with the greatest urgency. However, unless the issues of migration and disease are understood and dealt with effectively, it is unlikely that the greater struggle to control and manage AIDS can be won