2014 Volume E97.A Issue 11 Pages 2097-2106
Wireless communications for the control of industrial equipments need to send a large amount of short packets frequently and to improve frame efficiency. The OFDM frame of wireless local area networks has short preambles that are used for timing synchronization and coarse frequency offset estimation. As the short preambles are repeated in a time domain, they occupies subcarriers intermittently. Therefore, in this paper, a new frame format with OFDM modulation in which data symbols are orthogonally multiplexed with the preamble symbols in the frequency domain is proposed. Two preamble sequences that are based on an IEEE802.11g short preamble sequence and a Zadoff-Chu sequence are examined. The ratio of transmission powers between the pilot subcarrier and the data subcarrier is also varied. The timing synchronization probability with those sequences has been evaluated on different channel models. It is shown through the experiment that the synchronization performance is almost the same as that without data multiplexing at Es/N0 of more than 8dB.
