Study of Carrier Frequency Offset Estimation and Compensation for OFDMA Systems
Date Issued
2010
Date
2010
Author(s)
Wu, Chun-Ye
Abstract
Orthogonal Frequency-Division Multiple Access (OFDMA) is a popular physical layer technique for wireless communication nowadays. Due to carrier frequency offset caused by local oscillator mismatch and Doppler Effect, frequency synchronization is a crucial issue for mobile communication. Although many literatures have proposed lots of solutions for OFDMA downlink, there are still lots of problems that degrade the performance in uplink.
At the beginning of this thesis, the pilots are inserted in transmitting signals to assist the CFO estimation. With the iterative algorithm, the perfect CFO estimation is achieved at the second iteration. In addition, we also try to exploit the banded matrix to reduce the computational complexity of the full matrix. Therefore, exploiting from such scheme, the low complexity estimation is obtained without sacrificing much performance.
Second, in the later chapter, we consider the problem of the unequal power allocation to the base station. Unequal power users would make strong multiuser interference on our estimation and degrade our performance. Therefore, in order to acquire better performance, a modified method is proposed to eliminate the interference before the estimation. Finally, considering practical implementation, we would set the environment to that of Taiwan High Speed Rail. With the proposed algorithm, the estimation performance can achieve the same quality in time-invariant channels.
Subjects
OFDMA
carrier frequency offset
multiuser interference
frequency synchronization
low complexity
unequal power allocation
Taiwan High Speed Rail
Type
thesis
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