Synchronization in WLAN

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Sample Clock Synchronization (cont’d) • The amount of rotation angle experienced by different subcarriers is given by j e π T s 2 kt∆l T u where k: Subcarrier index l : OFDM symbol index T s : Duration of the total OFDM symbol T u : Useful data portion of the symbol • The angle depends on both subcarrier index and the OFDM symbol index • Hence, the impact is larger on the outermost subcarriers and increase with consecutive OFDM symbols • Large subcarrier rotation prevents the correct demodulation WLAN Synchronization 16.3.2004 © Hafeth Hourani 24
Estimating the Sampling Frequency Error • The approach of estimating the sampling frequency error rely on the pilot subcarriers • The pilot subcarriers are used to transmit known data called pilot symbols • The receiver can utilize the pilot symbols to perform synchronization functions • The sampling frequency offset is estimated by using the knowledge of the linear relationship between the phase rotation caused by the offset and the pilot subcarrier index WLAN Synchronization 16.3.2004 © Hafeth Hourani 25
Page 1 and 2: S-72.333 Postgraduate Course in Rad
Page 3 and 4: Next . . . •Overview • Timing E
Page 5 and 6: Synchronization in Packet-Switched
Page 7 and 8: Timing Estimation Overview Timing E
Page 9 and 10: • Packet detection test H H 0 1 :
Page 11 and 12: Packet Detection Methods Timing Est
Page 13 and 14: Received Signal Energy Detection (c
Page 15 and 16: • The result of the DSW does not
Page 17 and 18: Preamble Aided Detection (cont’d)
Page 19 and 20: Packet Detection Methods Timing Est
Page 21 and 22: Symbol Timing Algorithm • Symbol
Page 23: Sample Clock Synchronization • Th
Page 27 and 28: Next . . . • Overview • Timing
Page 29 and 30: Frequency Synchronization Approache
Page 31 and 32: Channel Estimation • Channel Esti
Page 33 and 34: Frequency Domain Channel Estimation
Page 35 and 36: Next . . . • Overview • Timing
Page 37 and 38: References • OFDM Wireless LANs:
Page 39: Homework • Q1. In that equation i

Synchronization in WLAN

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