A design and implementation of timing and frequency synchronization for OFDM-based WLAN

This paper presents a design and implementation on timing and frequency synchronization for OFDM-based WLAN. Synchronization in OFDM-based receiver is critical for performance and needs a great deal of hardware resources. Based on the discovered symmetries between real and imaginary values in short preamble of IEEE 802.11, applying the symmetries of a short preamble can reduce the hardware complexities of a matched filter to 30% of multipliers and 80% of adders necessary for an existing cross-correlator. For frequency synchronization, we also propose the phase estimation method using a binary search to identify the phase of a complex short preamble. It does not need to employ divider or memory to find out the phase. The OFDM-based WLAN PHY containing the proposed synchronization block is implemented on a field-programmable gate array of XCV8000, and its utilization factor amounts to about 25% of all slices.