Data Transmission Over Pilot Tones in OFDM based Wireless Systems

Pilots till date are used only for transmitting a known sequence for synchronization. In such systems pilots and training sequences are transmitted with the same minimum power governed by the modulation scheme used in the data sub–carriers. It has been found that the pilots enjoy extra signal to noise power ratio than required to achieve the required performance. Hence it is advocated in this paper, the exploitation of available extra signal energy in the pilots for data transmission without loosing synchronization. Initial results report a gain in terms of bandwidth of about five percent for IEEE 802.11a type technology. For other OFDM based wireless systems even more gain is expected. The increase in efficiency achieved via this scheme is not as high as compared to other newly proposed multiple input multiple output schemes, but it has several advantages, such as: Utilizing the existing frame format with very little changes. Further the existing demodulation schemes and receiver baseband and front end algorithms can function as usual. Does not require any additional hardware extension. Only the phase correction algorithm needs to be changed. Theoretical analysis supported with simulation results are presented to establish the claim in this document.