In wireless communication, low propagation delay and low power requirements of satellite are key requirements which makes low earth orbit (LEO) satellite preferable over others. Over the years a plenty of researches had been done in this field of satellite handover management, but the problem remains unsolved. One such method is the reservation of a few channels specifically for handover calls. One demerit of this scheme is that not all channels are available for allocation of new calls, leading to an increase in new call blocking probability. Also this scheme may lead to unnecessary reservation of channels for handover even when the number of handovers is very small. During such a period the reserved channels could have been used for allocation of new calls. So, in this paper we are going to propose a new Neighbour Location Based Channel Reservation scheme for efficient utilization of resources (channels) in handover and new channel allocation in LEO Satellite communication. In this scheme, we are reserving few channels in each spot beam especially for handoff based on the number of mobile stations in neighbour locations and the average handover call arrival rate. In the simulation, this approach reduces the unnecessary complexity and unnecessary reservation of resources (channels) which in turn reduces the complexity of the communication network.
In wireless local area network (WLAN), mobility management becomes a sophisticated issue of research due to the limited coverage of the Access Points (AP). For the successful communication between the mobile nodes (MN), every node should be connected with an access point (AP) during their operating mode, irrespective of their mobility. When a MN travels into the coverage area of its current AP, no special technique is required to maintain the connectivity. But when a MN travels out of the coverage area of its current AP and tries to associate with another AP, a delay occurs during the handover of connection which leads to a failure of connection. Throughout the last few years plenty of researches had been done to reduce this handover delay by reducing the scanning delay as the scanning process causes 90% of the total handover delay. In this paper, we propose a new scanning technique where the most potential AP is chosen according to the direction of the MN. First, we fit a polynomial equation along the trajectory of its motion and then to predict the direction of motion, we analyze the slope of the trajectory. Our simulation results show the effectiveness and accuracy of our proposed scheme in practical field.
Urban and peri-urban agricultural practices are degrading throughout the developing world owing to unprecedented urban sprawling and consequent expansion of built-up areas. This study attempted to assess the changing land use/land cover patterns of Kolkata Metropolitan Area, India from 1990 to 2020 with special emphasis on the transformation trajectories of its urban and peri-urban agriculture as a case study using free and open-source software and multi-temporal geospatial database. It also aimed to project the transformation scenario of croplands in 2030 through application of the artificial neural network algorithm of the freely available Modules for Land Use Change Evaluation plugin. Results revealed a persistent spread of built-up areas by engulfing croplands, wetlands, vegetation and water bodies throughout the assessment period. An overall loss of 181.11 sq. km of croplands between 1990 and 2020 was estimated and found to be more prominent in the northern, eastern, and south-eastern parts of the study area. If the existing socio-economic framework and administrative mechanism would prevail as usual, then the projected land use patterns of 2030 would predict a further decrease of 15.46 sq. km in cropland area thereby culminating to a total 37.39% of it original extent since 1990. A theoretical three-stage model of land use conversion was developed from the empirical results as well as field observations and validated with the findings of the projected scenario. It indicated two primary conversion patterns for the study area, viz. (1) natural area to cropland to fallow land and then to built-up, and (2) natural area to fallow land to built-up. Few necessary management measures were suggested to mitigate this persistent loss of croplands and other natural areas.
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