| Multiple Input Multiple Output–Orthogonal Frequency Division Multiplexing(MIMO-OFDM) is one of the core technologies in the next generation broadbandwireless communication systems, which has greatly high spectrum efficiency.However, it is very sensitive to timing synchronization, which includes framesynchronization (signal capture) and symbol synchronization. The accurate timingsynchronization is a prerequisite to communication system demodulation anddecoding. Especially for transmission system based on the OFDM technology,synchronization performance is very important to the overall system performance, andis the difficulty and key technology of system design.In MIMO-OFDM system, on a certain receiving antennas at one moment, thereceiving signal is superposition of the signals from all the transmitting antennas. Inaddition the multipath effect, the mainpath signals from different transmittingantennas arrive at the receiving antennas with time offsets. Hence, the implement offrame synchronization becomes difficult. On the other hand, distributed antennasystem (DAS) is considered as an open architecture for future communication systems.With the DAS architecture, transmitting antennas and receiving antennas are sparselyplaced, and the frame synchronization becomes more difficult and more complex. Atpresent, the research of frame synchronization for MIMO-OFDM with DAS mostlyfocuses the training sequence design and improvement of the matching correlationalgorithms. Due to a lack of system theory model, the existing research is still in thetentative phase.In order to solve this problem, this paper researches performance analysismethod and threshold selection criterion of frame synchronization for MIMO-OFDMwith DAS. We propose an accurate performance analysis method to provide atheoretical reference for the frame synchronization algorithm design. Moreover, thecorrect frame synchronization probabilityPc orrectis deduced by using the proposedperformance analysis method. Finally, the accuracy and effectiveness of the proposedmethod is verified with different transmitting antenna numbers and through theapplications to several existing algorithms UPSP、CAZAC and OVPSP.Based on the proposed performance analysis method, this paper proposes athreshold selection criterion of frame synchronization for MIMO-OFDM with DAS. By this criterion, receiver would achieve perfect frame synchronization in theory. Anyrequired performance of correct frame synchronization can be satisfied with theproposed threshold selection criterion above a specified signal noise ratio (SNR).Moreover, a simplified criterion is presented based on the3σ principle of normaldistribution. Finally, the proposed threshold selection criterion is proved to beaccurate and valid by Monte-Carlo simulation in the different systems with differentMIMO transmitting antenna numbers and the specified SNRs. |
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