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| The capacity demand for mobile network has been growing very fast in recent years, which makes the mobile network operators exploring new mobile network structure based on cloud infrastructure, i.e. C-RAN. The C-RAN system makes centralized processing and large-scale cooperative transmission possible, and it may bring remarkable improvement on system performance. In this paper, a mode of inter-RRH timing offset (TO) is proposed to evaluate the C-RAN with timing alignment error (TAE). Results show that although C-RAN has a great potential on improving system performance, it can only get nearly half of the gain under TAE. To suppress the effect of TAE, the phase compensation beamforming is performed at RRH side using feedback information of UE side. The beamforming can offset the effect of phase shift caused by TAE. It is observed that the algorithm performs well and the system only suffers about 5%~10% performance loss compared with nearly 50% loss with no phase compensation. |
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| Keywords:C-RAN; Timing Offset; Phase Compensation; Beamforming |
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