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HELPER Network

Heterogeneous Efficient Low PowEr Radio (HELPER) Network for enabling off-the-grid connectivity

Introduction

In the past year, United States was hit with several devastating Hurricanes. Similar natural and man-made disasters are undesirable but sometimes unavoidable. In these scenarios, one of the most critical infrastructure affected are often communication networks [1]. This imposes the need for the responders and affected individuals to be best equipped with wireless communication technologies to maintain connectivity. To ensure feasibility and scalability of such wireless networks, the proposed device must be portable, low power, low cost and should provide basic services to users in a seamless manner. An important assumption during the design stage is that there is no infrastructure available to connect to an existing Internet. This means that the new network that is set up should be self-sustained and provide basic services that will be critical during the recovery phase of the aftermath. In this project, we develop a radio network (hardware and communication protocols) and supporting software (applications for mobile device) that is capable of establishing an independent, low cost, lower power wireless network providing critical communication to off-the-grid users during the aftermath of a disaster. One of the major objective of this work is to reduce the cost of the proposed device as much as possible (< $ 40) such that each household can have one in their emergency kit and easily set it up when other communication infrastructure is disrupted. These nodes along with the nodes deployed by responders can form a wireless ad hoc network connecting users among themselves and to a responder control station (RCS) (when applicable). Therefore, in this project, we will develop Heterogeneous Efficient Low PowEr Radio (HELPER) network to be deployed in such scenarios. We will also develop an energy efficient routing algorithm that aims to maximize the network lifetime to ensure extended coverage of the affected area. Finally, we will develop a Website Application (Web App) and Android Mobile Application (Mobile App) that will enable users to seamlessly connect to the HELPER network. In this manner, the proposed device helps the community to setup an off-the-grid cooperative communication network that provides critical services.

Design Objectives

Each HELPER is equipped with Wireless Fidility (WiFi) to establish a local area network (medium range, high data rate) and a second wireless technology, LoRa that enables low power, long range links to form an ad hoc network in cooperation with other HELPERs. The primary goal of our network design are as follows,

Nodes in HELPER Network

ANDRO HELPER Development Prototypes











As shown in Fig. 1, there are mainly three types of nodes in the HELPER network,

  1. Static Node (SN): The network is predominantly setup with portable yet static HELPERs. We refer to these nodes as static because we envision it to operate in a relatively fixed location (household, hospitals, roadside, public buildings etc.). These nodes have the largest battery and solar panel that supports 24/7 operations. In cases where only temporary network is required (for few hours), the design can be altered to make the device more portable, lighter and solar panel can be eliminated. The current design of the node is aimed to survive at least a day or two in absence of sunlight or extend for multiple days in presence of ample sunlight. These SNs are also the primary source of cached information (maps, emergency phone numbers etc.). Caching is critical to reduce transmission load, delays and energy consumption of the network. The static node forms a local WiFi network where devices (phones, tablets, PC or Laptops) can connect to the HELPER (which acts as an access point) to communicate among themselves, other users within one-hope neighborhood and the RCS.
  2. Mobile Ground Node (MGN): The MGNs constitute of HELPERs carried by vehicles and HELPERs carried by first responders or other members of search and rescue team. The HELPER on vehicles does not need battery or solar panel as it will draw the required energy from the operating vehicle itself. In contrast, the mobile node that the first responders carry will have much smaller battery to ensure better portability (estimated to weigh under 300 g). This means that the lifetime of the node will be limited to 8 − 9 hours of operation. Since these MGNs are to be used by responders rather than the survivors, these nodes will interact with the Mobile App in “first responder” mode to update the location of nearby survivors and alert their health and other status.
  3. Aerial Mobile Node (AMN): When network is setup, based on accessibility, there might be parts of the network that is disconnected from the entire network due to node failure, locally disruptive channel conditions or uneven distribution of nodes during the setup period. The goal of AMN is to identify these isolated HELPERs and act as a temporary sink node. The isolated HELPER can upload the information about the users currently connected to the given HELPER and this information is carried by the AMN to the RCS. The AMN also indicates which locations need more nodes to be deployed in order to repair disconnected parts of the network. The AMN are the most costly and least energy efficient (taking into consideration the energy for flight) among the three but is required in critical scenarios where road access might be completely cut-off. The AMN does not use WiFi since it does not interact directly will users rather only uses LoRa links to communicate with other HELPERs. More about the different deployment scenarios are discussed in the next section and design of these nodes are discussed in Section 2.

More Details Coming Soon…

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