Network Allocation Vector (NAV) and "beam access control" (BAC) techniques
are provided to address data collision problems in WLANs wherein APs
provide wireless network access in a service area defined by multiple
sectors via use of a switchable antenna system or the like. Preferably,
every time the AP visits a sector and before the AP moves on to the next
sector, the AP can set the NAV equal to the time it will take until its
next visit. Alternatively, or in addition, a BAC bit is transmitted by an
AP to control access to the AP by WTRUs disposed in a service sector in
which the BAC is transmitted.