Performance Evaluation of IEEE 802.11ax Midamble and Impact of Interference

Kanghyun Lee, Saewoong Bahk

Abstract: To deal with channels under mobility, IEEE 802.11ax high efficiency (HE) wireless local area network (WLAN) has proposed the use of midamble, implemented by periodically inserting HE long training field (HE-LTF) between orthogonal frequency division multiplexing (OFDM) symbols carrying data. Since mobility channels provoke error vector magnitude (EVM) due to the difference in channel state information (CSI) at preambles and data symbols, subframes of the latter part of the aggregate medium access control (MAC) protocol data unit (A-MPDU) shows a lower subframe success rate (SSR). By exploiting midambles, the receiving station overcomes the limitations of mobility channels and adaptively follows channel dynamics. However, the interference during frame reception degrades SSR severely if midambles are used. This is because midambles under interference suffer corrupted CSI and generate additional error vector when decoding. In this paper, we develop IEEE 802.11ax features as well as midambles on our link-level simulator and evaluate the performance of midamble under mobility channels and interference.