2. Location Estimation Methodology
Using a summary of our ILS methodology presented in Galvan-T ´ ejada et al. 7. This consists of two phases described
in the following sections.
2.1. Data Collection
To collect magnetic-field information from an indoor environment 1, a set composed of 1,000 data points from a
magnetometer sensor of a smartphone is used to generate a signature. To get data points, the user must walk around
the indoor environment with an approximate speed of 1 m/s during 10 seconds with the smartphone at the user’s waist
as is shown in figure 1. The number of seconds (10) to collect the signature was chosen because in average 10 seconds
is enought time to cover an common indoor room location of 6 m2 walking at the proposed speed of 1 m/s.2
In order to estimate the number of signatures needed to create a model, the equation 1 proposed by Eberhardt 10 was
used to determine the minimal number of experiments in multivariable process with aim to have statistical validation.
In the equation 1, x is the minimum number of experiments, and N is the number of variables.
x = log2(N) + 1