SOURCEFORGE » RALF » 2014 Design and integration of a TooWay-based multi-purpose terminal

h1. Problem positioning

The satcom lab of Télécom Bretagne will soon be equipped with a TooWay/KA SAT facilities (bi-directional internet via satellite) that come in two flavours: a fixed antenna for access within the lab and a fly away antenna for on-the field access. On-the-field access is provided through a transportable terminal (see pictures below). The transportable terminal integrates a modem, networking facilities and end-devices (e.g., DECT/VOIP phones).

The objective of this project is to design and integrate the portable terminal taking into account all aspects: communication, networking and physical integration.

h1. Introduction

The transportable terminal provides services in inhospitable and isolated locations. In particular, our aim consists in bringing internet access through wired and Wi-Fi IP network and to provide internal and external VoIP calls. The terminal is composed of two antennas (one fixe and another one mobile) and a modem to receive the signal from the Ka-Sat satellite and convert it into digital signal. One router, a Dect and some IP phones constitute the second part of the terminal to share the network between the internet access and the phone calls. In the first part of the project, we have identified the use cases and the corresponding network architecture (address and routing plan). Then we proceed with the integration of the networking and communication components in a ruggedized flight case. Later we have connected the transportable terminal to the fixe antenna to realize some tests and demonstrations of the overall system. The terminal is transportable with its mobile antenna and could be used during important and catastrophic events by the red cross for instance to keep them in touch with the head quarter.

h1. Content

h2. I.Design of the Ka-Sat Terminal

h3. a.Study of User Cases

h3. b.Design of the Network Architecture

h3. c.Description of the Components 

h2. II.Networking and Communication between components

h3. a.Networking of components

h3. b.Establishment of the VoIP link 

h3. c.Quality of Service and Fire-wall

h2. III.Integration on the Ka-Sat Terminal

h3. a.Mounting of the components on the ruggedized flight case

h3. b.Connection to the antenna and Tests

h1. List of figure

h1. I.Design of the Ka-Sat Terminal

h2. a.Study of User Cases

+Use cases 1:+ Internet Access through wired IP network

The use case 1 consists in providing internet access through wired network. The user must connect its machine to the local area network via a wired cable. For instance the user will connect its machine with an Ethernet cable to the router. The router will furnish a local IP address via DHCP. Finally the user will have access to internet and services as HTTP, SMTP, FTP, Streaming... Since the networking is sharing amongst users, there will be some restrictions on the data rate.   

+Use cases 2:+ Internet Access through wireless IP network

The use case 2 consists in providing internet access through wireless network. The user must connect its machine to the local area network through Wi-Fi. The router will furnish a local IP address via DHCP to the user. Nevertheless, the user must be authorized by the administrator to be connected to the network thanks to a logging and a password. In fact the Wi-Fi can be received by anyone around the terminal that is the reason why we must restrict the connection by a password. Finally, after connection, the user will have access to internet and services as HTTP, SMTP, FTP, Streaming... Since the networking is sharing amongst users, there will be some restrictions on the data rate.   

+Use case 3:+ Voice over IP

The use case 3 consists in providing a phone call over Internet. The user will dial a number on hardphones available in the flight case. The call will be establish via voice over IP. There are two possibilities, whether it is an internal call, and so the speaker we intend to reach is on the same local network. In this case there should not have too much time delay and the phone call is totally free. Whether it is an external phone call, and there will have at least 400 ms of time delay. It is corresponding to the time the wave takes to travel from the two speakers via the satellite. In this case the phone call is not free, so some restrictions as international call must be establish.     

h2. b.Establishment of the VoIP link 

h2. c.Description of the Components 

Component : Mikrotik RB2011U series

Type : Router

Role : The primary purpose of the router is to provide a local area network to connect the components. Next the router will furnish a quality of service in order to differentiate the prior packets  as VOIP from packets will low priority. In addition the router will establish a firewall to secure the network.