A method for determining a position uses an access point array, a reference station, a location server and a client terminal. The reference station may include a GPS receiver to acquire and track GPS satellites. GPS data may be provided to the location server. The access point array may be configured to minimize interference and may be coupled by a network to the location server. The client terminal may include a GPS receiver. A frequency offset for the client terminal may be determined by examining a frequency offset of the reference station and relative offset frequencies of the access points. This frequency offset may advantageously increase the sensitivity of the client terminal to GPS signals. The client terminal may provide GPS data to the location server, which server may determine the position of the client terminal based on data from the client terminal and the reference station.