A method and apparatus for calculating a location of a device is provided. A likelihood of the device being located at a particular location point or a particular location floor is determined using a likelihood calculation at each of a plurality of locations. The location point or location floor is then identified as that location having an associated highest likelihood calculation. The likelihood calculation includes calculating a distance from the device to each of a plurality of reference routers including one or more virtual coplanar reference routers, wherein each of the one or more virtual coplanar reference routers comprise a projection of a non-coplanar reference router onto the floor.