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Beacons Impact study Thomas Deillon & Thin Nguyen July 23rd 2014OverviewIntroductionProblematicAnalysis methodologyExperimentationRecommendation / ConclusionBack-Up SlidesGVA Airport Use Case

2IntroductionINTRODUCTION4General information

A Bluetooth Low Energy (BLE) beaconis a device that continuously advertisesa signal (between 100ms and 10s).

This signal can be detected by BLE-capabledevices to sense location, show location-basedcontent and trigger pre-defined actions.

A beacon is uniquely identified by its ID and the major and minor values, often representing a retailer (major) and a specific store area (minor). An arbitrary numberof devices can receive this signal and there is no connection between smartphone and beacon required. Thus the beacon does not store any user data or application-specific content. The beacon offers additional services if a device (only one at a time) is connecting via BLE, see the following table. Every service and service characteristic is identified through a 128-bit value (UUID).

4INTRODUCTION5WIFI Frequency usedWiFi is a signal that emits on 2.4Ghz (as Bluetooth) and works on 14 different channels :

Best practices recommend to use only channels 1, 6 and 11 as they are the non-overlapping channels (i.e. not generating interferences).

INTRODUCTION6BEACONS Frequency usedBeacons use 3 Bluetooth frequencies, named channels 37, 38 and 39, as shown below :

For most beacon manufacturers, the frequency of emission is chosen dynamically. The beacons are probing their environment and perform hopping until they find a free frequency.

INTRODUCTION7Beacon manufacturers

Different manufacturers for different usage. Be particularly aware of the battery life and the operational process.

As an example, how to manage stock when a beacon cannot be switched off and its battery life is only 200 days ?PROBLEMATICPROBLEMATICOVERVIEW

Beacons can trigger an app on your smartphone to send notifications or promotional coupons as you entered a specific zone, such as a shop, cafe or airport lounge. It can also direct you to areas of interest and provide additional information on specific items, making museums and art galleries another potential user of the technology.

It would be interesting to use them in Airports but how will they coexist or impact existing services (e.g. Wi-Fi) ?-Sita is implementing beacons in airports. -Sita take the opportunity to monitor the beacon for the other companies and airlines within the airport, thus constructing a registry that would centralize the command center of the beacons in one program. This would also allow a frequent update of the feed that is delivered from the beacon (EX: from 13h -15h promotional offer on food, and the same beacon from 16 -18 shoe advertisement)-One registry for multiple companies

9ANALYSIS METHODOLOGYANALYSIS METHODOLOGY11Theory BASEDBeacons frequencies are in between non-overlapping Wi-Fi channels 1,6 and 11 and consequently wont impact WiFi AP on channels 1,6,7,8,9,10,11,12.

Moreover, beacons where made in a way to minimize the interference. The output power of WiFi is much higher than Bluetooth and even using Wi-Fi channels 2,3,4,5,13,14 will only have a minor impact.

To investigate the impact of beacons on WiFi, we measured the maximum bandwidth throughput via FTP and the use of an Access-Point. The same experiment was then repeated with beacons on the path.

The first PC is a FTP server and hosts a 200 MB file. The second PC is a FTP client and downloads the 200 MB file via the Access-Point.

ANALYSIS METHODOLOGY12EXPERIMENTATION approach - Bandwidth1

FTP server

FTP clientWiFi Ch. 1ANALYSIS METHODOLOGY13WiFi analyzer is an application available in the Google Play store that can transform an Android device into a WiFi reader.

Channel Wi-Fi viewerWi-Fi Broadcasting Power and ChannelEXPERIMENTATION approach WIFI Channel2https://play.google.com/store/apps/details?id=com.farproc.wifi.analyzer13ANALYSIS METHODOLOGY14Bluetooth Smart Scanner is an application available on the iTunes store that can transform a device into Beacon reader.

Discover BeaconsSee Beacon's Channel and StrengthEXPERIMENTATION approach Beacon Reader3

14ANALYSIS METHODOLOGY15The Spectrum Analyzer enables the viewing of 2.4Ghz channels usage & interferences

EXPERIMENTATION approach Spectrum4

Blue: < 10% utilizationGreen: 20% utilizationYellow: 40% utilizationRed: > 50% utilizationGraph amplitude over time for all frequencies in the selected band, much like a seismometer graphs earthquakes.

The height of the graph shows how loud devices are (amplitude), and the intensity of the color shows how often signals are occurring. The more intense the color, the more often the frequency is in use. This is called utilization, which is similar to duty cycle and airtime usage. For example, if a frequency has 40 percent utilization, it is only free for use by other transmitters for 60 percent of the time.A blue spike or shape indicates a short signal, like a clap. A red spike or shape indicates a long, continuous signal, like an air horn

15EXPERIMENTATION200 MB file transfer under ideal conditions(no other WiFi AP nearby or similar interferences checked with the spectrum analyzer)EXPERIMENTATION

17REFERENCES TEST1

FTP server

FTP clientWiFi Ch. 6 Download timeDownload speedAverage of 3 tests133.6 seconds11.92 Mbits / sThis numbers are used as reference tests for the following experimentation

200 MB file transfer on Ch. 6EXPERIMENTATION18INTERFERENCES TESTS2Youtube video (10% BW) on Ch. 4Download timeDownload speedAverage133.5 seconds11.92 Mbits / s

The first AP is set on Channel 4 (2.427Ghz) to simulate 10 beacons on Channel (38) 2.426Ghz, which should interfere with the transfer rate on the second AP set on Channel 6 (2.437 Ghz)Beacons use, amongst others, the 2.426Ghz frequency (channel 38) which theoretically doesnt impact WiFi when set on Channel 1, 6 or 11. The following test is to prove this point:

The download time and speed shows that it doesnt impact the WiFi (Ch. 6) performance and confirms the theory approach where Beacons + Wifi on Channels 1,6,7,8,9,10,11,12 dont impact each other

EXPERIMENTATION19WORSE CASE SCENARIO3200 MB file transfer with 13 beacons at 4db/20ms

FTP server

FTP clientWiFi Ch. 4

Download timeDownload speedDecreasingAverage of 3 tests138 seconds11.6 Mbits / s< 5 %In this worse case scenario (Beacons on 2.426Ghz and WiFi on 2.425Ghz), the bandwidth impact is minor (5% decrease). We can conclude that even in a situation where WiFi is on Channels 2,3,4,5,13,14, the Beacons impact on WiFi performance is negligible (