The OFDM technology has been extensively used in many radio communication technologies. For example, OFDM is the core technology applied in WiFi, WiMAX and LTE. Its main advantages include high bandwidth utilization, strong noise immunity and the capability to resist frequency selective fading.
However, OFDM technology is not only applied in the ﬁeld of radio communication, but has also been developed greatly in acoustic communication, namely the so called acoustic OFDM.
Thanks to the acoustic OFDM technology, the information can be embedded in audio and then transmitted so that the receiver can obtain the required information through certain demodulation mechanisms without severely aﬀectingthe audio quality.
This study mainly discusses how to embed and transmit information in audio by making use of acoustic OFDM. Based on the theoretical systematic structure, it also designs a simulation system and a measurement system respectively. In these two systems, channel coding, manners of modulation and demodulation, timing synchronization and parameters of the functional components are conﬁgured in the most reasonable way in order to achieve relatively strong stability and robustness of the system. Moreover, power control and the compatibility between audio and OFDM signals are also explained and analyzed in this thesis.
Based on the experimental results, the author analyzes the performance of the system and the factors that affect the performance of the system, such as the type of audio, distance between transmitter and receiver, audio output level and so on.
According to this analysis, it is proved that the simulation system can work steadily in any audio of wav format and transmit information correctly. However, due to the hardware limitations of the receiver and sender devices, the measurement system is unstable to a certain degree.
Finally, this study draws conclusions of the research results and points out unsolved problems in the experiments. Eventually, some expectations for this research orientation are stated and relevant suggestions are proposed.
Source: Linköping University
Author: Wang, Shuai