Two-stage wireless network emulation

Testing and deploying mobile wireless networks and applications are very challenging tasks, due to the network size and administration as well as node mobility management. Well known simulation tools provide a more flexible environment but they do not run in real time and they rely on models of the developed system rather than on the system itself. Emulation is a hybrid approach allowing real application and traffic to be run over a simulated network, at the expense of accuracy when the number of nodes is too important. In this paper, emulation is split in two stages : first, the simulation of network conditions is precomputed so that it does not undergo real-time constraints that decrease its accuracy ; second, real applications and traffic are run on an emulation platform where the precomputed events are scheduled in soft real-time. This allows the use of accurate models for node mobility, radio signal propagation and communication stacks. An example shows that a simple situation can be simply tested with real applications and traffic while relying on accurate models. The consistency between the simulation results and the emulated conditions is also illustrated

A realistic path loss model for real-time communication in the urban grid environment for Vehicular Ad hoc Networks

Wireless signal transmission is influenced by environmental effects. These effects have also been challenging for Vehicular Ad hoc Network (VANET) in real-time communication. More specifically, in an urban environment, with high mobility among vehicles, a vehicle’s status from the transmitter can instantly trigger from line of sight to non-line of sight, which may cause loss of real-time communication. In order to overcome this, a deterministic signal propagation model is required, which has less complexity and more feasibility of implementation. Hence, we propose a realistic path loss model which adopts ray tracing technique for VANET in a grid urban environment with less computational complexity. To evaluate the model, it is applied to a vehicular simulation scenario. The results obtained are compared with different path loss models in the same scenario based on path loss value and application layer performance analysis. The proposed path loss model provides higher loss value in dB compared to other models. Nevertheless, the performance of vehicle-vehicle communication, which is evaluated by the packet delivery ratio with different vehicle transmitter density verifies improvement in real-time vehicle-vehicle communication. In conclusion, we present a realistic path loss model that improves vehicle-vehicle wireless real-time communication in the grid urban environment

INDOOR LOCATION SENSING USING WLAN

The purpose of this project was to produce an indoor location system using WLAN IEEE 802.11b in Access Point (AP) infrastructure setup without additional external hardware. The system was developed in MATLAB platform that comprises of location sensing algorithm (Nearest Neighbor), signal strength database, client-server interface and graphical user interface (GUI). The basic idea was to build a database of signal strength information for various predetermined locations. Using the Nearest Neighbor algorithm, this database can be used to determine a particular location provided that a set of signal strength is given. As for the location sensing system's performance, it had a precision in terms of average distance error of 5 m and an accuracy of 72.2 %. The justification of these results was that noise, interference, multi-path effect, indoor propagation loss and random movement in the environment affectedRF signals

Effects of physical channel separation on application flows in a multi-radio multi-hop wireless mesh network: An experimental study on BilMesh testbed

Cataloged from PDF version of article.In this paper, we introduce BilMesh, an indoor 802.11 b/g mesh networking testbed we established, and we report about our performance experiments conducted on multi-hop topologies with single-radio and multi-radio relay nodes. We investigate and report the effects of using multi-radio, multi-channel relay nodes in the mesh networking infrastructure in terms of network and application layer performance metrics. We also study the effects of physical channel separation on achievable end-to-end goodput perceived by the applications in the multi-radio case by varying the channel separation between the radio interfaces of a multi-radio relay node. We have observed that the difference between TCP and UDP goodput performances together with the delay and jitter performance depends on the hop count. We also observed that assigning overlapping channels with a central frequency separation of 5-15 MHz may render the CSMA mechanism used in 802.11 MAC ineffective and hence reduce the overall network performance. Finally, we provide some suggestions that can be considered while designing related protocols and algorithms to deal with the observed facts. (C) 2013 Elsevier Ltd. All rights reserved

An Investigation paper on Congestion Control Policy

In the advancement of network technology traffic affects performance factors like file synchronization, communication throughput and overall all the scenario where one are having continues connectivity of business to the rectifying organizations, all the business functionality are going for the achievement of paperless communication infrastructure where one are deploying all his working by the internet technology such high speed network communication infrastructure always required well suited congestion less architecture scheme to achieve quality of services ,In the field of different communication area there are many applications has be running at present for all type of users likesenior, junior and all business users categories. Network proposed many protocols and algorithm for the improvement in flow of the network,Ethernet project 802 and protocols series 802.11a/b/c/d/e has been working at network layer in which user’s found some times network work well with priorities choice of network connection but sometimesstruggles with the same.To analyze the actual report of congestion policies here author of the paper are presenting analytical study so that one can understand the lack of functionality in communication with specific network implementations