Performance evaluation of the RPL Protocol in fixed and mobile sinks low-power and lossy networks.

Low-Power and Lossy-Network (LLN) are usually composed of static nodes, but the increase demand for mobility in mobile robotic and dynamic environment raises the question how a routing protocol for low-power and lossy-networks such as (RPL) would perform if a mobile sink is deployed. In this paper we investigate and evaluate the behaviour of the RPL protocol in fixed and mobile sink environments with respect to different network metrics such as latency, packet delivery ratio (PDR) and energy consumption. Extensive simulation using instant Contiki simulator show significant performance differences between fixed and mobile sink environments. Fixed sink LLNs performed better in terms of average power consumption, latency and packet delivery ratio. The results demonstrated also that RPL protocol is sensitive to mobility and it increases the number of isolated nodes.

The Rawls-Tawney theorem and the digital divide in postindustrial society.

The digital divide continues to challenge political and academic circles worldwide. A range of policy solutions is briefly evaluated, from laissez-faire on the right to “arithmetic” egalitarianism on the left. The article recasts the digital divide as a problem for the social distribution of presumptively important information (e.g., electoral data, news, science) within postindustrial society. Endorsing in general terms the left-liberal approach of differential or “geometric” egalitarianism, it seeks to invest this with greater precision, and therefore utility, by means of a possibly original synthesis of the ideas of John Rawls and R. H. Tawney. It is argued that, once certain categories of information are accorded the status of “primary goods,” their distribution must then comply with principles of justice as articulated by those major 20th century exponents of ethical social democracy. The resultant Rawls-Tawney theorem, if valid, might augment the portfolio of options for interventionist information policy in the 21st century