The Research Of Congestion Control And Error Correction Coding Of Short Message Service Transmitting Based On DSP

In the research of intelligent transportation, the communication of real time data becomes more and more important. The communication of real time data lets vehicle and users exchange real time traffic information with traffic control center and makes the function of vehicle navigation system more effect. However, as the characteristics of the transmission are not ideal and the impacts of the additive white noise exist, in the actual channel of signal transmitting, the errors from the received signal are inevitable. When the wireless network is in the stage of congestion the delay of short message data transmitting will increase, which will affect the precision of position severely.In this thesis, the reliability of data transmitting is researched by the technology of the error correcting encoding and the convolution code (2, 1, 3) is adopted to realize encoding. The principle and software realization method of the convolution code are analyzed. When encoding, the data of the convolution code can be achieved effectively using the shift of DSP and the capability of double-word processing. During the process of decoding program realization, firstly, in the circumstance that the error-rate of channel of signal transmitting is below one percent, which is testified by MATLAB simulation, the optimal depth of backtracking of the decoding is confirmed. Then the large number of computation is void through data table, which make the decoding compact and rapid. So the characteristic of the decoding is very sound. The validity of the error correcting the encoding is testified by practical testing data, which take a foundation for improving the quality of data transmitting.As to delay of shot message data transmitting, the channel of the wireless communication is analyzed utilizing queue theory, the Short Message Queuing model is established and the parameters of short message, such as the queue length, the average waiting time etc. are deduced, the rationality of which is testified by MATLAB simulation of the model of SMSC and which provide the theory foundation of congestion control.Moreover, the hardware circuit system of realization algorithmic is designed, which includes power module, clock module, resetting module, JTAG simulation interface module, program memorizer module and so on. Otherwise, the electric level transform of memorizer and the configuration of clock module are analyzed in detail.