A novel adaptive rate control algorithm for SC-FDE systems

A novel adaptive rate control algorithm is proposed in order to improve the spectrum efficiency for single carrier frequency domain equalization (SC-FDE) systems over Rayleigh fading multipath channels. With the variance of the channel state information (CSI) like signal to noise ratio (SNR), the proposed algorithm not only searches for the current optimal modulation and coding scheme (MCS) in the MCS switching table to improve the spectrum efficiency, but also calculates the average modulation and coding scheme duration (MCSD) of the current MCS to avoid too frequently operating the channel estimation and switching the MCS, reduce the system overhead and further improve the spectrum efficiency. Then the current optimal MCS is passed to the transmitter and receiver to implement. The next optimal MCS would be searched for only if the time counter exceeds the current average MCSD. The spectral efficiencies for the proposed MCSs are also determined. The simulation results validate the proposed algorithm and show that under the premise of meeting the target bit error rate (BER), the adaptive system performing the proposed algorithm has a higher spectral efficiency than that of the non-adaptive system.