Design And Implementation Of GSM Soft-Modem On Android Smart Terminals

With the rapid development of the information technology, mobile telecommunication which is not limited by time and place has seized the world’s attentions. At the same time, the Android mobile smart terminal has occupied mast part of the smart terminals. The majority of Android mobile smart intelligent terminals support for dual mode (GSM+3G) and use the architecture that the CPU processor and modern chip are separated. Owing to the complexity of the process and the independence among various modes, and the enhancement of the data handling capabilities, most of the CPU resource is excessed. Thus, this paper will mainly discuss the transition of GSM modem chips task into CPU processor, putting forward soft-modem architecture. It integrates different standard wireless communication systems on a universal Android platform, which can improve the flexibility and reduce the cost to maximum, having important application value.This paper will propose soft-modem architecture which will solving the traditional problem of incompatibility with each other between the old and new communication standard, because of the single and fired function of baseband chips based on dedicated hardware. On a universal Android platform, use software to realize communication protocol stack and digital signal processing which gives full play to the flexibility of software. This paper, firstly discuss the achievement of GSM soft-modem architecture based on the correlative technique of non-real-time system of Android mobile smart terminal software and hardware platform. Secondly, the paper will design and achieve the hardware of open source system running on Android system platform. It will introduce universal CPU based on ARM Cortex-A9to replace traditional GSM, and will help to achieve the communication function of traditional GSM baseband chips by way of software defined radio (SDR), and it will also help to let the traditional GSM baseband protocol stack and DSP operate on Android mobile terminal equipment’s universal CPU by form of software. These steps will meet the demands of software baseband architecture. Meanwhile, due to the prior requirement of soft-modem system to hardware resource, the optimization of GSM software baseband processing and internal thread is claimed on Android platform.Finally, the optimization of Viterbi mechanism with complex calculation is requested by SIMD technique in GSM system to meet the requirement of signal processing efficiency.