first portion of a preamble applying power loading to the combined bit stream applying eigen steering to the power loaded bit stream and combining a second portion of the preamble with the eigen steered bit stream for transmission the first portion of the preamble includes an ht preamble and the second portion of the preamble includes a legacy preamble application_number US 31485905 A description under the ieee 802 11n standard the transmission of the preamble is in two portions for beamforming mode the legacy part is transmitted without pre coding eigen steering and the ht high throughput part that uses the same data path as payload is eigen steered in general the coarse agc automatic gain control and coarse synchronization is achieved through the legacy part for 802 11n systems an example system is described in s a mutjaba u201c tgn sync proposal technical specification u201d a contribution to ieee 802 11 04 889r2 january 2005 incorporated herein by reference because there is no pre coding operation on the legacy portion of the preamble in beamforming systems all the operations such as coarse agc and coarse synchronization can be performed in the time domain identical to the 802 11a system for the mimo part the ht stf high throughput short training field is used for fine agc tuning and ht ltf high throughput long training field is used for fine synchronization and mimo channel estimation because pre coding is applied to the ht part of preamble fine.