Based on the frequency-domain analog-to-digital conversion (FD ADC), this work builds a low-complexity sequential searcher for robust symbol synchronization in a 4 × 4 FD multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) modem. The proposed scheme adopts a symbol-rate sequential search with simple cross-correlation metric to recover symbol timing over the frequency domain. Simulation results show that the detection error is less than 2% at signal-to-noise ratio (SNR) ≤5 dB. Performance loss is not significant when carrier frequency offset (CFO) ≤100 ppm. Using an in-house 65-nm CMOS technology, the proposed solution occupies 84.881 k gates and consumes 5.2 mW at 1.0 V supply voltage. This work makes the FD ADC more attractive to be adopted in high throughput OFDM systems.
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