A survey of performance enhancement of transmission control protocol (TCP) in wireless ad hoc networks

This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Springer OpenTransmission control protocol (TCP), which provides reliable end-to-end data delivery, performs well in traditional wired network environments, while in wireless ad hoc networks, it does not perform well. Compared to wired networks, wireless ad hoc networks have some specific characteristics such as node mobility and a shared medium. Owing to these specific characteristics of wireless ad hoc networks, TCP faces particular problems with, for example, route failure, channel contention and high bit error rates. These factors are responsible for the performance degradation of TCP in wireless ad hoc networks. The research community has produced a wide range of proposals to improve the performance of TCP in wireless ad hoc networks. This article presents a survey of these proposals (approaches). A classification of TCP improvement proposals for wireless ad hoc networks is presented, which makes it easy to compare the proposals falling under the same category. Tables which summarize the approaches for quick overview are provided. Possible directions for further improvements in this area are suggested in the conclusions. The aim of the article is to enable the reader to quickly acquire an overview of the state of TCP in wireless ad hoc networks.This study is partly funded by Kohat University of Science & Technology (KUST), Pakistan, and the Higher Education Commission, Pakistan

Intended and unintended consequences of democracy promotion assistance to Georgia after the Rose Revolution

What are the political consequences of democratization assistance to regimes transitioning from authoritarian rule? By exploiting the downstream effects of a field experiment designed to encourage citizen monitoring of Georgia’s 2008 parliamentary elections, we evaluate the political consequences of one type of democracy promotion aid. The intervention increased citizen activism, but it also had the unanticipated effect of suppressing overall voter turnout by approximately 5%. We hypothesize that the civic education campaign was interpreted as a sign of increased political attention to a selected voting precinct, which suppressed opposition turnout. Two additional experiments provide additional evidence for the hypothesis

Educational opportunities and learning outcomes of children in Peru: A longitudinal model

The last few decades have seen an enormous increase in pre-school, primary, and secondary school enrolment in Latin America and other developing regions in the world, to the point where it is close to 100 per cent in many countries. This is aligned with international movements such as Education for All (see, for example, UNESCO 2007), which calls for universal primary enrolment by 2015. However, the assessment of achievement of students has often shown poor results. The issue has become not only whether children go to school, but also what and how much they learn there; an example of this is the recently issued strategy for education from the World Bank, called Learning for All (World Bank 2011). The tendency for measuring achievement has resulted in the creation of several national and international programmes in developing countries, such as the Latin American Laboratory for the Measurement of Educational Quality, sponsored by UNESCO (2010).1 This programme has carried out two rounds of evaluations in over a dozen countries of the region, measuring achievement in language, mathematics, and science among primary school students. The most recent results show that low achievement is associated with several individual and family characteristics, such as living in a rural area, speaking an indigenous language, low parental education, and child work (UNESCO 2010)