A method of sub-channel independent network allocation vector (NAV) management by a wireless station (STA) in a wideband wireless communications system is proposed. In the wideband system having multiple sub-bands, each NAV for a corresponding sub-band is independently managed. The protection duration for each NAV is independent for each sub-band and the threshold or update rule for NAV modification is also independent for each sub-band. The threshold or update rule for NAV modification may also be different when the NAV is generated or propagated by an OBSS STA. Furthermore, early termination of NAV is allowed if the NAV is set by an OBSS STA only.