Research On Synchronization Technique For Wireless Communication System In High Speed Environment

With the rapid development of mobile Internet, people’s requirements on mobile communication is increasingly high. As a part of mobile Internet, vehicular networking flourishes. Along with the people’s security needs and multimedia communications needs become more and more intense, people’s quality requirements to vehicle communications are also constantly improving.According to vehicle communication, which is the common application of high speed wireless communications, the current study on its wireless communication technology mainly focus on the LTE and IEEE802.11p. As a quasi4G wireless communication technology, which introduce the key technology of OFDM and MIMO, increases significantly the rate of data transmission and supports a variety of bandwidth allocation, high mobility and low delay.802.11p is extended and modified from802.11a, doubling its guard interval and using64point OFDM technology, enhance the ability to resist the multipath propagation and Doppler effect in the automotive environment.Whether LTE or IEEE802.11p, OFDM technology is used in their physical layer. As a frequency reuse technology, OFDM has become a key technology of high speed data transmission system depends on its good anti fading and anti interference capability and high spectrum utilization in bad wireless communication environment and the limited spectrum resources situation. Because the subcarriers are orthogonal to each other, OFDM is very sensitive to frequency offset. Frequency offset between the transmitter and receiver, especially the Doppler frequency shift in high speed mobile environment will make the orthogonality between OFDM subcarriers destroyed, forming ICI and making demodulation performance deteriorated rapidly. So synchronization technology has become the key technology of vehicle communication in high speed environment.In view of this situation, this paper has conducted the research to this problem from the following aspects:Firstly this paper introduces the physical layer structure of LTE and802.11p and the basic principle of OFDM, which is used in common; Secondly I investigate and analyse the synchronization of OFDM technology in wireless environment, mainly on the data aided synchronization algorithm; Thirdly based on the research of existing synchronization algorithm and according to the frame structure and characteristics of LTE, I put forward a joint estimation algorithm of frequency offset of LTE based on primary synchronization sequence and reference signal and verify with simulation. Finally the algorithm we use on carrier frequency synchronization and phase tracking is implemented on FPGA hardware, and the hardware implementation of the algorithm is verified by the video transmission for the802.11p protocol under the vehicle communication.