Design And Implementation Of Embedded IMS Voice Terminal

With the rapid development of Computer and Internet technology,the combination of embedded technology and network communication has been attracted more and more attentions.VoIP is a kind of digital voice transmission technology based on IP networks.Embedded IMS voice terminal will be an important application of embedded system in the future,and have a broad development prospects.SIP Protocol is the most widely used signaling control protocol in VoIP system,which is rapidly adopted by the telecommunication industry to build the next generation of communications network.SIP is an application-layer control Protocol that can establish,modify,and terminate multimedia sessions or conferences.Based on the analysis and reaserch on SIP protocol and embedded technology,this thesis researches a method to implement a embedded voice terminal which is based on SIP.This thesis adopts the embedded real-time operating system FreeRTOS,develops embedded IMS voice terminal overall design with low power consumption and cheap chip, includes following works:1) On the principle of low power consumption, low cost and small volume, compare various mainstream chip,determine using Nuvoton Technology Corp 32 ARM Cortex-MO microcontroller core ISD9160 SoC as core processor, whose high integration architecture, so designers need not use a variety of peripheral chips;compare various mainstream operating system,determine running open source,superfine kernel and free FreeRTOS embedded real-time operating system on it.2) Mainly consider the anti-interference and high stability of the circuit,complete hardware schematic circuit of the processor module,Wi-Fi module,user interface module,etc,then schematic and PCB is made with Altium Designer 09 which is a kind of EDA software.3) Analysis the main features of ISD9160,complete the transplantation of embedded real-time operating system FreeRTOS on ISD9160,mainly includes system configuration, the initialization of the stack,a switch to enter and exit the critical area,the task switching,start the task scheduling,and the realization of the system clock.4) Analysis the characteristics of echo in VoIP system,design a kind of echo cancellation method.Complete the design of the voice terminal configuration management, implement the online update of configuration information.After the hardware circuit debugging and product comprehensive testing,the voice terminal can achieve the normal phone, including four scenarios:communication between hardware terminal and soft terminal,communication between hardware terminal and GSM mobile phone,communication between hardware terminal and PSTN phone,communication between the hardware terminal,achieved the desired purpose.Project achievements have been through IMS compatibility tests by Liaoning mobile,and on trial by a iron ore corporation in Huludao.