Format of cells:
id,lat,lon,mcc,mnc,lac,cellid,range,nbSamples,created_at,updated_at
Format of measures:
id,lat,lon,mcc,mnc,lac,cellid,id_of_Cell,userid,extraInfo,created_at,measured_at,signal

Note:

id_of_Cell is the id (the entry) in cells table. It's not the cellID!!!

lat,lon  of cells are updated according to measures....
Currently, lat and lon are simply computed as the average of all measures
but this may change in the future for a better computation

if signal is null, this mean that this info was not available when measure
has been done