The Research Of Frequency Synchronization Alogrithm In Heterogeneous Wireless Mobile Communication System

With the rapid development of wireless communication technology, variouskinds of emerging wireless access technology and communication network togetherprovide heterogeneous mobile communication environment for users. Theheterogeneous mobile communication environment has different standards, differentprotocols and different services. The research about merging in service and terminalwill be the hot issues in the next generation of wireless communication. The WirelessLocal Area IEEE802.11a, The Wireless Man Area IEEE802.16e and LTE use thetechnology of Orthogonal Frequency Division Multiplexing (OFDM) in physical layer.The communication system based on the technology of Orthogonal FrequencyDivision Multiplexing has a common problem that the system is sensitive offrequency offset. In order to find the robust method to solve the estimation offrequency offset, the paper at first researched the content of the three protocols andthe principle of frequency synchronization, and then proposed the frequencysynchronization scheme for the heterogeneous communication systems base thetechnology of OFDM. Based on the above three different heterogeneous network, thecommon existing frequency synchronization problem has been researched, whichmakes the preparation work for the synchronization for the merging terminals in thefuture heterogeneous environment.First, novel scheme of frequency synchronization principle in IEEE802.11a,IEEE802.16e and LTE is presented. The contents consist of the analysis of OFDM, theprocess of frequency synchronization and the algorithm.Then, a scheme is proposed to solve the problem of frequency synchronization inIEEE802.11a, IEEE802.16e and LTE. This Scheme content includes three parts. Thefirst part proposed an alogrithm that is used for detecting the length of cyclic prefix indifferent OFDM signals. The method of detecting is that the length of the peakplatform is equals to the length of prefix in the cross-correlation operation. The lengthof cyclic prefix is determined through detecting the length of peak platform. In thesecond part, the symbols timing and frequency offset estimation alogrithm adapted inheterogeneous communication systems is proposed. In order to improve theperformance, the alogrithm has considered the resistance to multipath interferenceability, time synchronization accuracy and complexity. The method of increasing the resistance to multipath interference is at first estimate the region of cyclic prefixwithout symbol interference by calculating delay power spectrum or exploits thecorrelation between cyclic prefix and original data parts in OFDM singals, and thenuse the correlation of this region to achieve the synchronization. Considered thecomplexity, the paper proposed a low complexity time and frequency estimator whichhas coarse synchronization and fine synchronization operating model. In the third part,a carrier phase tracking algorithm based on heterogeneous pilot and the technology ofchannel estimation is proposed. The channel estimation method is vital to carrierphase tracking. The paper researched the performance of alogrithm in differentchannel estimation technologies.Last, the FPGA design is implemented for the symbols timing and frequencyoffset estimation algorithm base on cyclic prefix and the functional and post-routesimulation result verified the correction of the design.