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Mobility Testbed Development (Openbts Testbed) and Its Integration with Voiit, Webrtc & NG-911 Testbeds 90/100

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Mobility Testbed Development (Openbts Testbed) and Its Integration with Voiit, Webrtc & NG-911 Testbeds 90/100 Mobility Testbed Development (OpenBTS Testbed) and its Integration with VoIIT, WebRTC & NG-911 Testbeds 90/100 Sushma Sitaram A20137272 May 09, 2014 1 Table of Contents 1 Abstract ....................................................................................................................... 2 2 Introduction ................................................................................................................. 3 3 Goals Of The Project .................................................................................................. 3 4 Milestones Of The Project .......................................................................................... 4 5 Infrastructure Needed.................................................................................................. 4 6 GSM Architecture ....................................................................................................... 5 7 Openbts Application Suite .......................................................................................... 6 8 Logical Diagram ......................................................................................................... 7 9 Physical Diagram ........................................................................................................ 8 10 Execution Of The Project............................................................................................ 9 10.1 Testbed Setup ...................................................................................................... 9 10.2 Initial Testing .................................................................................................... 10 10.3 Openbts Configurations .................................................................................... 10 10.4 Asterisk Configurations .................................................................................... 11 10.5 Run Asterisk...................................................................................................... 11 10.6 Phone Settings & Network Access ................................................................... 12 11 Challenges Faced ...................................................................................................... 12 12 Functionalities & Ladder Diagrams .......................................................................... 13 12.1 Authentication ................................................................................................... 13 12.2 Location Update ................................................................................................ 14 12.3 Call Control ....................................................................................................... 15 13 Tasks To Be Carried Out Next .................................................................................. 15 14 Conclusions ............................................................................................................... 16 REFERENCES ................................................................................................................. 17 CWID: A20137272 Project Report - Final [email protected] 2 1 Abstract This project aims to develop a GSM testbed implemented using Range Network’s OpenBTS Development Kit and attempt its integration with other existing testbeds- VoIIT, WebRTC and NG-911, developed at the Real Time Communications (RTC) Lab. The integrated system would serve as an excellent testbed for conducting research and educational experiments. In this report, the major milestones set for the project, the infrastructure needed for setting up the GSM testbed, steps followed to implement the designed testbed whilst closely following the project goals and the challenges faced during the implementation, would be discussed in detail. Along with listing out the future work, the possible solutions to existing limitations are also suggested. Also, upon successful completion of the integration of the various testbeds, the probable usage scenarios of the integrated testbed are also indicated. CWID: A20137272 Project Report - Final [email protected] 3 2 Introduction OpenBTS (Open Base Transceiver Station) is a software-based GSM access point, allowing standard GSM-compatible mobile phones to be used as SIP endpoints in Voice over IP (VOIP) networks [1]. OpenBTS is an open-source software developed and maintained by Range Networks [4]. The Range Networks’ OpenBTS Development Kit is used to build the GSM testbed. OpenBTS eliminates the need for complex and expensive GSM core components and replaces them with modern VoIP network components. IIT’s RTC Lab has a fully operational VoIP system called VoIIT. WebRTC APIs enables users to share information (video, voice, data) between web browsers, without installing any plug-in. IIT’s RTC Lab has developed a WebRTC testbed. Next Generation 911 (NG911) refers to an initiative aimed at updating the 911 service. In addition to calling 911 from a phone, it intends to enable the public to transmit text, images, video and data to the 911 center. IIT’s RTC Lab has developed a NG-911 testbed. The integration of the different testbeds is to be attempted. The integrated system will serve as an excellent testbed to carry out SIP and GSM performance evaluation lab experiments. It will also facilitate students of the VoIP and data networks class to better understand GSM and VoIP functionalities by conducting lab experiments. 3 Goals of the Project The overall goal of the project is to build a testbed with the OpenBTS GSM base station and integrate it with other existing testbeds at IIT, viz. VoIIT, WebRTC and NG-911. The integrated system is to be used for testing and analyzing the behavior and performance of cellular networks & SIP. The following activities are involved in the project: . To study the feasibility of integrating OpenBTS testbed with VoIIT, NG-911, WebRTC testbeds. To design a GSM testbed with the Range Networks’ OpenBTS Development Kit: 5150 series. To configure and setup the GSM system to be able to make calls between mobile phones, between a softphone and mobile phone using the service provided by the OpenBTS network. The accuracy and correct working of the testbed to be ensured by performing Location Update tests, mobile originated and mobile terminated calls. To integrate the fully functional and tested OpenBTS testbed with existing VoIIT testbed. To integrate the fully functional and tested OpenBTS testbed with existing NG-911 testbed. To integrate the fully functional and tested OpenBTS testbed with existing WebRTC testbed. CWID: A20137272 Project Report - Final [email protected] 4 . Connect phones to the OpenBTS GSM network and test the integrated system by placing calls and testing the handling, routing, behavior and performance of the calls between the GSM and SIP network interfaces. To sniff the air interface using “AirProbe” software during different stages like: Location Update, Mobile Originated Call and Mobile Terminated Call. Observe the authentication procedure and also compare the messages captured at the air interface with those mentioned in the GSM specifications. Another branch of this project would be to connect two such GSM base stations to a base station controller implemented using OpenBSC software. 4 Milestones of the Project The project has been divided into several milestones which are as follows: . Develop a low cost & easy to install private GSM network testbed using Range Networks’ OpenBTS Development Kit . Integrate the testbed with existing VoIIT, NG-911 and WebRTC testbeds . Connect 2 OpenBTS base stations to a Base Station Controller implemented using OpenBSC software . The integrated system would be used for research purposes, by conducting tests to study the behavior and performance of cellular networks & SIP . The integrated system would also be used for educational purposes, by students of the data networks and VoIP classes . Applications are both research and educational 5 Infrastructure Needed The following are the infrastructure needed in executing this project: . OpenBTS Application Suite A complete OpenBTS C2.8 installation comprises of several distinct applications [2]: 1. OpenBTS – The actual OpenBTS application, containing most of the GSM stack above the radio modem. 2. Transceiver – The software radio modem and hardware control interface. 3. Asterisk – The VoIP PBX or “softswitch”. 4. Smqueue – The RFC-3428 store-and-forward server for text messaging. 5. Subscriber Registry – A database of subscriber information that replaces both the Asterisk, SIP registry and the GSM Home Location Register (HLR). The subscriber registry servers usually form a hierarchy with the top-level server holding the full database and level-level servers caching recently accessed records [2]. Unlocked GSM Handsets + SIM cards . Antenna: The Range Networks Development kit is connected to an antenna for transmission and reception of radio waves CWID: A20137272 Project Report - Final [email protected] 5 . DC Power Supply: A 12V DC power supply is used to power up the base station. The power supply used is a 12V-15V variable power supply and caution must be taken to never exceed 12V! . Ethernet switches and cables for network connections . PC with Linux OS and Asterisk installed: A softphone (twinkle) installed on a separate PC running Asterisk, is interfaced to the OpenBTS development kit through an Ethernet interface. This is used to make calls from the softphone to the mobile phone and vice versa . Console: A console
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