MAC-aware rate control for transport protocol in multihop wireless networks

International audienceTransport layer performance in IEEE 802.11 mul-tihop wireless networks (MHWNs) has been greatly challenged by wireless medium characteristics and multihop nature which are the sources of several types of packet loss including collision, random channel errors and route failures. Rate control transport protocols, the candidates for multimedia streaming applications suffer from high loss rates and end-to-end delay in MHWNs. A common research direction is that the rate control mechanisms at transport layer should be aware of MAC layer contention to keep the network load at a reasonable level. In this paper, we introduce a new MAC metric which reflects the contention and congestion levels more accurately. The metric is then used to improve the rate control mechanism of a rate-based transport protocol in MHWNs. The simulation results show that the adapted mechanism introduces significant performance improvement in MHWNs

Cross layer metrics for improving transport protocols in multihop wireless networks

Session Posters & DemosInternational audienceNotre travail s'inscrit dans l'amélioration des protocoles de transport dans les réseaux sans fil ad hoc multisauts. Nous présentons différentes métriques provenant des couches physiques ou liaison pour améliorer les performances de la phase de contrôle de congestion de TCP. Ce papier introduit une classification des métriques inter-couches pour améliorer le niveau transport

INVESTIGATING EFL TEACHERS’ PERCEPTIONS OF IMPLEMENTING ACTIVE LEARNING TECHNIQUES IN TEACHING SPEAKING

Active learning (AL) is widely implemented in Asia including Vietnam. However, to date, research on this method seems to be scarce, particularly in the context of Vietnam. This study aims to investigate teachers' perceptions of AL and its principles in teaching English speaking. In addition, the study also explores teachers’ attitudes about AL implementation and their concerns about applying this method to their teaching context. Ten teachers of English teaching at a university in the Mekong Delta, South of Vietnam participated in the study. A semi-structured interview activity was employed to collect data. The results showed that the teachers generally had a high level of understanding of AL teaching principles and showed positive attitudes toward the implementation of it. The results also revealed teachers’ concerns about implementing AL. In particular, three problems of large class size, students’ mixed language proficiency and time limitation were addressed. Accordingly, possible suggestions for a better implementation of AL in teaching English speaking in Vietnam and similar contexts elsewhere will be provided.  Article visualizations

Strict partitions and discrete dynamical systems

AbstractWe prove that the set of partitions with distinct parts of a given positive integer under dominance ordering can be considered as a configuration space of a discrete dynamical model with two transition rules and with the initial configuration being the singleton partition. This allows us to characterize its lattice structure, fixed point, and longest chains as well as their length, using Chip Firing Game theory. Finally, we study the recursive structure of infinite extension of the lattice of strict partitions

Organisational Baseline Study: Overview report for My Loi CSV, Vietnam (VN02)

This report covers the Organisational Baseline Study (OBS) for the CCAFS climate-smart village My Loi in central Viet Nam. During October and November 2014 interviews were conducted with ten organisations working or collaborating with farmers and/or the community in Ky Anh district in Ha Tinh province. The My Loi research site lies in the uplands of the north central coast. The region has four but increasingly variable seasons, increase in frequency and magnitude of storms and tropical low-pressure systems, increase in intensity of dry and hot westerly wind (Laos wind). The main farming systems comprise a blend of crop-livestock systems with the main crops being rainfed rice, cassava, peanut, and acacia. This OBS report supplements the qualitative village baseline studies at the same location. The objectives of the organisational baseline study are to: Provide indicators to monitor changes in behaviours and practices of locally relevant organisations that have climate change related activities in Ha Tinh over time Understand the provision of information/services at the local level that informs farmers’ decision making about their livelihood strategies in response to climate chang

Participatory identification of climate-smart agriculture priorities

With the concept climate-smart agriculture (CSA) being relatively new, there is a need to test and develop practical and systematic methodologies and approaches for documenting and evaluating CSA practices in the field. The implementation of CCAFS’ Climate-Smart Villages (CSV) involves identifying, assessing and selecting climate-smart farming practices. This report contains three sections: (i) a framework for identifying and assessing CSA in the field with a long list of CSA indicators in identifying and monitoring CSA interventions; (ii) cost-benefit analysis of some selected climate-smart farming systems; and (iii) the participatory process of prioritizing CSA options with the villagers. The work builds on our experiences from the My Loi CSV and its scaling domains in Ky Anh district, Ha Tinh province, in the north-central region of Viet Nam. English version: https://cgspace.cgiar.org/bitstream/handle/10568/75542/Participatory%20CSA_ICRAF_Final.pd

Microsimulation of impacts of tax and transfer in Viet Nam: Feasibility study

This paper assesses the feasibility of simulating the distributional impacts produced by various tax and transfer instruments in Viet Nam. Viet Nam's system of tax and transfer policies underwent frequent changes, in terms of diversity and adjustment scope. The most important source of data is the Viet Nam Household Living Standards Survey. Investigation of the survey data shows the wide-ranging feasibility of simulating tax and benefit instruments, though more details are available for transfer instruments. The microsimulation should thus focus more on the transfer instruments, which invites interests from a range of government agencies, international organizations, and non-governmental organizations