Sub-Carrier Assignment for Multimedia Traffic Over OFDM Wireless Channel

With the rapid growth of wireless access to the Internet, there has been an increasing demand in providing high data rate real time traffic such as audio and video over wideband wireless channels. However, the transmitted multimedia traffic experience frequency-selective fading in wideband wireless channels. By dividing the wideband channel into several smaller sub-channels and sending multimedia traffic in parallel orthogonal sub-channels, which is widely known as orthogonal frequency division multiplexing (OFDM), the frequency-selective channel can be transformed into a set of frequency-flat channels. OFDM has become a prospective technique for the next generation wireless communications. In this paper, we analyze the effect of sub-carrier assignment on the transmitted multimedia traffic. By increasing the number of sub-carriers, each sub-channel behaves practically as a quasi-static one, such that frequency-selective fading and intersymbol interference (ISI) can be alleviated. The multiplexing of sub-carriers is introduced to combat the variability of wireless channel, but the performance of wireless channel would also be degraded. We present a quality assessment of audio and video traffic over OFDM wireless channel based on sub-carrier assignment. Simulation results show that proper sub-carrier assignment could significantly reduce errors during high rate multimedia transmission