by default access points send beacon frames every how many ms
Beacon frame Infrastructure network access points send beacons at a defined interval, which is often set to a default 100ms. In the case of an ad hoc network where there are no access points, a peer station is responsible for sending the beacon. After an ad hoc station receives a beacon frame from a peer, it waits a random amount of time. After that random timeout has elapsed, it will send a beacon frame unless another station has already sent one. In this way, the responsibility of sending beacon frames is rotated amongst all the peers in the ad hoc network, while ensuring that beacons will always be sent.
Assisted GPS Standalone/self-ruling GPS devices depend solely on information from satellites. A-GPS augments that by using cell tower data to enhance quality and precision when in poor satellite signal conditions. In exceptionally poor signal conditions, for example in urban areas, satellite signals may exhibit multipath propagation where signals skip off structures, or are weakened by meteorological conditions or tree canopy. Some standalone GPS navigators used in poor conditions can't fix a position because of satellite signal fracture and must wait for better satellite reception. A regular GPS unit may need as long as 12.5 minutes (the time needed to download the GPS almanac and ephemerides) to resolve the problem and be able to provide a correct location.[2]