A novel threshold adjustment scheme for adaptive transmission systems

The adverse impact of the time-varying multipath channel on the transmission signal can be alleviated with the use of adaptive modulation and coding (AMC) technique in wireless communication systems. However, if the switching thresholds between different modulation and coding schemes (MCSs) are not adjusted effectively when the channel characters change markedly, the system performance would deteriorate significantly. In order to mitigate the above problem, a novel threshold adjustment (TA) scheme for adaptive transmission systems is proposed in this paper. The proposed TA scheme not only determines the current optimal transmission strategy to improve the spectrum efficiency according to the instantaneous channel state information (CSI), but also adjusts the MCS switching thresholds to maintain the optimal transmission when the channel varies greatly. The numerical and link level simulation results both show that the proposed TA scheme improves the spectrum efficiency and adjusts the thresholds effectively to the time-variation of the multipath channel. So the proposed TA scheme enables the communication system to better adapt to the complex electromagnetic environment of the wireless channel.