In a wireless local area network system, a sharing access point (AP) may determine a long training field (LTF) subcarrier pattern for each of multiple streams, wherein an LTF symbol is used for at least one stream among a first to a third stream, the number of the LTF symbols is determined on the basis of the number of antennas of a shared AP having the maximum number of antennas among multiple shared APs associated with the sharing AP, and the first to the third stream are assigned different subcarrier patterns. The sharing AP may transmit information associated with the LTF subcarrier pattern.