Pre-FFT Type MMSE Adaptive Array Antenna to Suppress Asynchronous Interference for OFDM Packet Transmission

In this paper, a pre-FFT type MMSE adaptive array antenna for an OFDM packet transmission system to suppress asynchronous inter-system interference is proposed. The proposed receiver generates an initial weight based on an SMI algorithm by utilizing a periodic preamble structure. In the data period, it detects a new arrival of an interference signal by measuring the instantaneous fluctuation of the complex amplitude on each pilot subcarrier, and then regenerates the weight immediately by an iterative process in a few OFDM symbols. The average packet error rate of the proposed receiver is evaluated through computer simulations assuming an indoor line-of-sight environment and the IEEE 802.11a data packet structure. The simulation results show that the proposed receiver can suppress the asynchronous interference effectively by the weight regeneration using a small number of data symbols over a 2-path quasi-static fading channel.