A novel time interpolation channel estimation for IEEE802.11ac system

IEEE802.11ac is a 5GHz based very high throughput (VHT) wireless local area network (WLAN) standard with superior performance at channel capacity and transmission rate due to accurate channel estimation. Traditionally, the channel state information (CSI) of data field is obtained via training sequence in time domain such as VHI-LTF, which performs weakly in non-flat and slow fading channel. This paper proposed a novel time domain interpolation channel estimation algorithm to improve the estimation performance in non-flat and slow fading channel. Linear interpolation in time domain is taken between VHT-LTF symbols in current and the next frames signal, which can overcome the estimation error for channel fading variation. Simulation results show that the proposed scheme has better performance than conventional method considering estimation accuracy. 4 dB SNR improvement at 10⁻² BER performance compared to the conventional method is shown in the SISO system with the constellation mode of 256QAM. In addition, the influence of different modulation orders and antenna configurations are also studied so as to compare the accuracy of channel estimation with the modified method.