On limitation of clipping and filtering in IEEE 802.11g based wireless LAN system

IEEE 802.11g wireless LAN and IEEE 802.11n as its multiple-input multiple-output (MIMO) extension have become a de facto standard for recent indoor wireless communication technology. They adopt orthogonal frequency division multiplexing (OFDM) for its high bandwidth efficiency and robustness against multipath fading, but the OFDM signal generally bears high peak-to-average power ratio (PAPR). In IEEE 802.11g/n systems, in order to prevent distortion of signal in power amplifier (PA), a large input back-off (IBO) should be chosen prior to its amplification. This, in turn, reduces the efficiency of PA. Clipping and filtering (CAF) is a simple approach to mitigating high PAPR problem. However, since it causes signal distortion associated with nonlinear clipping, its applicability is limited considering that the practical system should meet the requirements in terms of error vector magnitude (EVM) and adjacent channel interference (ACI). In this paper, through an experiment using real PA, we investigate the effectiveness of the CAF and reveal its limitation in the framework of the IEEE 802.11g systems. We derive the most appropriate clipping ratio (CR) that satisfies the requirements of IEEE 802.11g.