A Novel Preamble Scheme for Packet-Based OFDM WLAN

In packet-based OFDM WLAN systems (IEEE 802.11a/g/n), each packet has a fixed-length preamble for synchronization and channel estimation purposes. The preamble carries no data information and hence causes considerable overhead during transmission when the payload is short and the data rate is high. In this work, we propose a new scheme, called superimposed preamble, to improve the efficiency of 802.11a alike systems. We design a new signal structure using variable data rate and propose an efficient receiver processing scheme to perform joint training (time and frequency synchronization and channel estimation) and data detection. It is shown that the proposed superimposed preamble system achieves training performance similar to the conventional 802.11a systems while gaining in robustness because of the reduced overhead.