Global warming and climate change have been a growing worldwide concern. Six sources, i.e., transportation, power, buildings, industry, agriculture and forestry, and land use, have been identified as major contributors to the rise of global carbon dioxide (CO2). The mobile industry is seen as a potential enabler to reduce greenhouse gases contributed by these six sources provided that appropriate measures are implemented. On the other hand, the mobile industry itself will also contribute to CO2 emission through network operations, mobile equipment, etc. To meet the requirement of low-carbon economy development, it is necessary to reduce the operation expenditure or energy consumption of mobile networks, while maintaining acceptable quality of service. This special issue explores and explains the scope and challenges of designing, building, and deploying GreeNets. In this regard, this special issue considers high-level contributions considering different topics including green mobile networks, system architectures, networking & communication protocols, applications, test-bed and prototype, traffic balance and energy-efficient cooperation transmission, system and application issues related to GreeNets.
Along its four papers, protocols and algorithms solutions are presented, furnishing important contributions to the state of the art and offering, at the same time, an important updated overview about emerging communication technologies for Green Communications and Networks.
The paper entitled “EE-ARQ: a Green ARQ-Based Algorithm for the Transmission of Video Streams on Noise Wireless Channels” , proposed by Alfio Lombardo, Carla Panarello, and Giovanni Schembra addresses an important issue related with the increase of the energy efficiency of telecommunications networks, and specifically wireless devices that present the highest energy consumption coefficient per bit transmitted among all the networking devices. However, making a network device green can cause performance deterioration. The target of this paper is to propose a new algorithm for the transmission of multiplexed rate-controlled multimedia streams over wireless channels. The algorithm is an energy-efficient variant of ARQ to exploit the correlation of the wireless channel behavior. In addition, in order to compensate transmission bandwidth reduction due to the energy saving policies, a cross-layer approach is applied introducing a source Rate Controller working to modify the video quality according to the state of the transmission buffer. An analytical model of the whole system is presented in order to evaluate performance and provide some guidelines to design the configuration parameters of the proposed algorithm.
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(Author: Joel Rodrigues