Virtual Subcarrier Assignment (VISA) for Spatial Filtering of OFDM Signals
Shinsuke Hara, Yong Qiang JIA · IEICE Transactions on Communications · 2006
In this paper, we propose a novel spatial filtering technique for orthogonal frequency division multiplexing (OFDM) signals called Vlrtual Subcarrier Assignment (VISA). Here, virtual subcarrier is a subcarrier which is not used for data transmission. When a wireless terminal is equipped with multiple antennas, VISA can easily achieve a space division multiple access (SDMA) by assigning a different spectral position of virtual subcarrier to a different user. To realize VISA in an already-existing OFDM-based wireless local area network (WLAN), we discuss an antenna weight control method in the preamble of a signal burst format designed for the IEEE802.11a standard and evaluate the bit error rate (BER) performance in typical indoor wireless environments.