10 1210 5 1220 2 5 1230 1 25 1240 ms under the doppler frequency fd 3 hz it can be seen that per performance is prominently enhanced in accordance with another method of transmitting a channel variation parameter as suggested herein information relating to a channel delay profile other than the above described channel variation parameters such as doppler frequency or velocity may be offered so that upon ppdu phy protocol data unit transmission the channel delay profile related information may be utilized in choosing a lgi long guard interval or sgi short guard interval like the above described channel variation parameter the channel delay profile related information also may be transmitted in various transmission schemes u2014 for example the information may be transmitted with a period constant unit of time or time e g association step of transmitting a channel variation parameter frame or as requested with no period or may be transmitted semi statically such embodiment also belongs to the scope of the present invention typically in relation to information on delay profile a recipient may estimate a maximum channel delay value by obtaining a channel frequency response through the ltf portion in the preamble and acquiring an estimated delay profile value upon conversion the channel frequency response in the time domain however in case the distance between the transmitter and the receiver is large or channel quality between the transmitter and the receiver is low such delay profile estimation suffers from low performance thus causing an inaccurate maximum channel delay value to be estimated in particular in the.