Testbeds

Testbed	Dimensions	Floors	Test points	Avg. spacing	Duration	Sessions
Offices	100×50 m	1, 0, -2	33+36+16	4.6 m	12 months	23
Campus	80×80 m	1, 0	13+13	12.5 m	12 months	20
Apartment	14×7 m	3	37	1.4 m	3 months	6

Floorplans and sampling locations

Radio sampling

The fingerprints are based on a set of raw (baseband, IQ) radio samples collected by a USRP B-210. Each radio band was sampled for 2 s as described below:

Band	Center frequency	Sampling rate (complex)	Antenna
FM	98 MHz	21 MHz	VERT400
GSM-900	935 MHz, 950 MHz	20 MHz	VERT900
DVB-T	498, 522, 554, 578, 594, 602	9.14 MHz	VERT400

(For more details on experimental setup, please check this paper)

The raw radio samples allow extraction of arbitrary fingerprinting features, even those not foreseen at the time of data collection. If you would like to extend AmbiLoc with advanced non-RSS fingerprints, please let me know: .

Structure

Dataset files are organized in a hierarchy of folders:

Testbed Name / Testbed Floor / Session ID / Coordinates / CSV files

Here, Session ID is the UTC time at the start of the measurement session (YYYYMMDD-hhmmss). Coordinates is the WGS-84 latitude/longitude of the test point (measurement location). The test points are predefined and fixed for the given testbed floor. (Note: the Apartment coordinates have been moved within 100m from the original position for privacy reasons).

RSS data

RSS measurements were calculated from the raw radio samples using GNU Radio toolkit with a GSM-specific module (gr-gsm). The RSS values are sampled at 10 Hz, resulting in 20 fingerprints per test point and per radio type.

	Band	Channel width	Fingerprint size
FM	87.5–108.5 MHz	100 kHz	210
GSM-900	925–960 MHz	200 kHz	175
TV (DVB-T)	498 to 602 MHz	8 MHz	6

The fingerprints are stored in a matrix form in human-readable CSV (comma-separated values) files, one file for each radio type. Each row represents one full-width RSS fingerprint, where each column corresponds to one radio channel.

FM

For FM, the following data are available:

fm.rss

RSS fingerprints (20×210 matrix)

fm.freq

Center frequency of each channel (210-element vector)

fm.fm-pilot-snr

FM stereo pilot SNR (the level of 19-kHz band above its neighboring 17 and 21 kHz bands in the FM-demodulated spectrum). This can be used for distinguishing unused radio channels from those with active FM stereo broadcasts.

GSM-900

Due to the wide width of the GSM-900 band, full-band GSM fingerprints are composed from two raw radio samples. Cell ID parameters were extracted using the gr-gsm module of GNU Radio.

gsm900.rss

RSS fingerprints (20×175 matrix)

gsm900.freq

Center frequency of each channel (175-element vector)

gsm900.(mnc, mcc, lac, cell_id)

Cell ID parameters (175-element vectors). For empty/unrecognized channels, default to zero.

TV (DVB-T)

The active TV channels have been identified manually in the first days of data collection. The initial set of five channels has later been extended with another one. The missing RSS data of that channel in the early sessions is replaced by "nan" string.

dvb.rss

RSS fingeprints (20×6 matrix)

dvb.freq

Center frequency of each channel (6-element vector)

Metadata

Each session includes a JSON-formatted file (session-info.json) that describes the testbed, its state (populated or empty) and ground truth precision. In the early sessions, the ground truth was established manually and should be consistent within few decimeters. Later on, the receiver position was controlled using laser rangefinders, ensuring that the ground truth across sessions is consistent within few centimeters.

The metadata also includes weather reports published by the nearby Luxembourg Findel airport. Weather information includes temperature, humidity, precipitation and several other parameters that can be useful for analyzing weather impact on localization performance.

Testbed	Ground truth	Human presence	Distance to meteo station
Offices	manual (coarse), laser (precise)	empty / populated	3 km
Campus	manual (coarse), laser (precise)	populated only	4 km
Apartment	manual (coarse) only	empty / populated	7 km