Sethuraman Rao

Performance measurement and analysis of long range Wi-Fi network for over-the-sea communication

Currently, Indian fishermen use handheld radios or satellite phones for offshore communication. While the former is based on broadcast communication with its range limited by Line-of-Sight, the latter is expensive. Therefore, lack of connectivity-at-sea is a huge problem for many Indian fishermen. Hence, this work prescribes a hierarchical point-to-multi-point backhaul network using long range (LR) Wi-Fi technology. It is a multi-hop network consisting of base stations and clusters of boats. Each boat-cluster forms a wireless mesh access network. A field-trial was conducted at sea to measure and analyze the coverage and connectivity of the P2mP LR Wi-Fi backhaul network, using commercially available 5 GHz base stations, antennas and customer premises equipment (CPE). Several parameters such as transmission power level, mechanical antenna tilt at the base station and channel bandwidth were fine-tuned to maximize the range. This paper discusses the observations and the results obtained.

Realizing cost-effective marine internet for fishermen

Offshore fishing is a common occupation providing the livelihood for tens of millions worldwide. Since each fishing trip takes 5-7 days, it could be a depressing and sometimes dangerous activity especially since the fishermen have no easy way to communicate with the mainland. Currently, there is no economically viable way to stay connected. We have developed a cost-effective system for marine internet connectivity that provides assured 40+ km range which can be further extended opportunistically. This paper describes the field trials conducted to practically realize the system and presents the encouraging results obtained.

Mobile infrastructure for coastal region offshore communications and networks

Marine fishermen risk their lives when they go as far as 120 km from the shore on a fishing trip lasting 5–7 days. They are completely cut off from the mainland. Cellular coverage exists only up to 12–15 km from the shore. In emergency situations, the fishermen have no way to call for help. Even under normal conditions, prolonged isolation from their family and friends causes mental depression. Since the marine fishermen are not economically well off especially in the developing countries, there has not been much commercial interest in addressing this problem. It is not seen as a profitable business proposition. However, addressing this problem will benefit the marine fishermen community immensely. Our center conducted interviews with several fishermen to understand this problem and came up with a cost-effective solution. The solution enables the fishermen to use the smart phones which they own already to get internet at sea using Wi-Fi. The Access Point (AP) on the boat connects over Ethernet to an onboard gateway to long range Wi-Fi backhaul network. The onshore base station is installed on a tower at a height of 50–60 m. Boats are also used as mobile base stations to extend the range of the network. This solution, when tested over the Arabian Sea, provided a range of 40+ km in the first hop and 20+ km every subsequent hop. This network can be operated on a cooperative community basis by the fishermen community at reasonable per capita CAPEX and OPEX. A pilot deployment is in progress in a coastal village community in Kerala, India, to gain operational experience.

Distributed task allocation and coordination scheme for a multi-UAV sensor network

Unmanned Aerial Vehicle (UAV) networks require successful mission execution, which is dependent on task planning and control. In this paper, we propose a distributed task allocation algorithm for a multi-UAV sensor network for sensing thorium intensities in the coastal areas of India. A power-aware coordination and planning approach is used to coordinate the activities of multiple UAVs. Depending on the availability of resources in each sensing UAV unit, each UAV initiates a task-scheduling algorithm and distributes its remaining tasks dynamically to other UAVs. The control station sends control information to the UAVs and receives the sensed parameters along with the location information from each UAV. The task allocation algorithm was simulated successfully using a network of static motes. The network was more effective and efficient with the use of this task allocation algorithm, thus contributing to improved mission execution in UAV networks.

A survey based analysis of propagation models over the sea

The design of communication architecture over a sea environment is challenging since it requires careful analysis of different factors such as multipath propagation, antenna characteristics and mobility that affect a signal. Although existing work has addressed a few factors, there is no work which provides a complete analysis of path loss incorporating such factors and how they affect on Received Signal Level. To get a clear picture of what work has been proposed in the literature, we present a survey article that gathers information about various propagation models used and proposed for maritime environment. We analyze each work based on the simulation set up, number of factors considered, error differences between simulated and experimental data and so on. We believe this article will help to identify the current state in simulation and analysis of communication links over the sea environment.

Development of a wireless sensor network for detecting fire and Gas leaks in a collapsing building

High-rise commercial and residential buildings are very common in todays modern cities and are subject to fires and gas leaks. When such buildings collapse, however, it is imperative that methods for the rescue and evacuation of residents be considered. This paper mainly focuses on detecting potential occurrences of cascading disasters due to fires and gas leaks in a collapsing building by frequently communicating with an Incident Management System via a wireless sensor network and UAVs. Using QualNet, an in-depth study of various antenna options and their characteristics is done and the selection of a suitable antenna, based on this study, is discussed. The network characteristics of ZigBee at different operating frequencies are also analyzed. Furthermore, an algorithm is proposed to deploy a wireless sensor network to detect fires, gas leaks, etc., using minimal number of ZigBee nodes.

A novel approach to urban flood monitoring using computer vision

Due to the high density of buildings and improper water drainage facilities, flash floods are prevalent in cities. In such scenarios, to extend timely aid, it is often required to estimate the level of flood in different parts of the affected zone. This paper presents a novel method employing participatory sensing and computer vision to estimate the flood level. The method involves the participants capturing and uploading images of the partially submerged static structures such as buildings, lampposts etc., using their smart phones or other intelligent devices. The captured images are geo-tagged and uploaded to a server. The feature matching algorithm, SIFT finds the corresponding matching feature points between the captured and a reference image at the server. The flood line is then estimated and drawn against the reference image. To optimize the network bandwidth usage, images with average resolutions are used. This method yields immediate and considerably accurate results thus helping in isolating areas that have been severely impacted for timely help.

Performance Assessment of an Extremely Challenged Mobile Infrastructure Network over the Oceans

A novel cost-effective network architecture for providing Internet connectivity to marine fishermen has been successfully prototyped by our research center. A pilot deployment is in progress in a coastal Indian village. This will improve the quality of life of the financially constrained marine fishermen who spend 5--7 days offshore on average for a single fishing trip; it will also help in their safety and security. The architecture employs multiple long range Wi-Fi (LR Wi-Fi) based infrastructure networks stitched together as backhaul. The access network consists of Ethernet and Wi-Fi mesh. The fishermen connect to the on board Wi-Fi access point cum router using their smart phones and are able to use all the apps and services on their smart phone. While the primary infrastructure network uses onshore base stations, the secondary infrastructure networks use boats as mobile base stations. Three field trials were conducted over the ocean using one onshore base station and two mid-sized boats known as trawlers. The performance of both primary and secondary infrastructure networks was assessed during these field trials. This paper describes the impressive results obtained in assessing the performance of the secondary infrastructure network.

Wireless Smartphone Keyboard for Visually Challenged Users

A Smartphone is a combination of a cell phone, a personal digital assistant (PDA), a media player, a GPS navigation unit and much more. To a blind and visually impaired (BVI) user, a Smartphone can assist and help connect with our modern day cyber social world. The only inconvenience to the BVI user is its user interface, which is a touch screen display. In this project, an economical user-friendly compact text-input device for a BVI Smartphone user is developed. This device is designed for daily use and it supports Braille text. The device is connected to the smart phone by Bluetooth interface. A Smartphone app pairs the phone with the device and switches the default keyboard service to use the device keyboard. The Smartphone operating system runs the screen reader when the keyboard is in use, giving real time audio feedback to the user. Thus, a setup for nearly seamless text input is provided to the BVI user. A low-cost Arduino based prototype has been developed as a proof of concept. As part of the future work, the prototype keyboard will be evaluated by BVI users and the results will be compared with other existing text input methods for BVI users.

A coplanar pentagonal antenna for wireless applications

Investigation of a coplanar pentagonal antenna is presented in this paper. The antenna offers a bandwidth of 9.48 % at 2.53 GHz with a gain of 4.39 dBi. The antenna has an omnidirectional radiation pattern. The advantage of coplanar antenna is that active circuitry can be mounted easily making it applicable for Monolithic Microwave Integrated Circuit applications (MMIC). The results are compared with a Bow-Tie antenna with the same substrate at same frequency.