Frequency domain symbol synchronization for OFDM systems

Abstract

In this paper, we propose a synchronization technique to reduce transmit power in order to develop an ultra low power transmitter. A sequence with digital power 0 dBW is used as the preamble at the transmitter. Compared with the traditional preamble specified in the IEEE 802.11 standards, the transmit power consumption is reduced by at least 24 dBW. However, a preamble with unit power cannot be easily detected in the time domain. Therefore, we propose a novel frequency domain symbol synchronization scheme to obtain the frame start. To our best knowledge, this is the first such published scheme that performs symbol synchronization in the frequency domain. In addition, the power consumption of this preamble is lower than other existing methods. Under an AWGN channel with a certain carrier frequency offset (CFO), the proposed method provides significant improvements compared with previously proposed methods. The proposed method provides at least 10 dB gain in extremely low SNR environment to achieve perfect timing synchronization in an AWGN channel. Furthermore, under frequency selective fading channels used in IEEE 802.16 standard with a certain CFO, the proposed algorithm performs always better than other previously proposed methods.