## 3 The FatBeacon Protocol  
The new FatBeacon protocol should not be confused with the previous ones, even though they are based on the same BLE technology. The main difference, apart from the advantage of not requiring an Internet connection for content streaming, is that FatBeacon is capable of storing and delivering content with several types of data, different from a URL alone. This allows, apart from the cases presentedin this paper, the implementation of more diverse projects, such as the creation of communications networks over large areas, which would facilitate communications in emergency situations. The signal emitted by a beacon can be of a spherical or omni-directional type. Besides, depending on the used protocol, beacons can emit a different type of content, although in most cases, it is a URL type (web address). In addition to transmitting a URL, beacons simultaneously emit other parameters packaged in the same Bluetooth signal, like the Transmission power (TX power), which usually has a fixed emission value, which determines the approximate emission range of each beacon and directly determines the battery consumption. Thus, the higher the TX level, the greater the strength of the signal and, consequently, the higher the consumption of battery power. The transmitting period or frequency is the time between two successive emissions. This value can also affect battery consumption because the higher the frequency, the higher the battery consumption. For example, a low frequency can be represented with 100 ms (corresponding to 10 emissions in one second), while a high frequency of 500 ms would imply that two emissions per second are made. The life-cycle of a beacon device depends mainly on those two values, TX power and frequency, so that the greater the requirements of the beacon, the sooner the battery will be depleted. On the one hand, beacon devices generally run on lithium batteries such as CR2032 (or button cells) because they have a large capacity for these low-power devices and can last for years. On the other hand, these devices could run on rechargeable energy using solar energy (with solar panels), which not only contributes to the use of renewable and clean energies, but also allows the implementation of unattended beacons in remote locations without the need to replace batteries from time to time. However, as shown in [14], these data can vary with respect to several factors such as emission power, algorithm optimization, antenna orientation, transmission power, beacon density per area, etc. Currently, we can find various types of beacon signals from different manufacturers supported by two different protocols. * Apple iBeacon: This beacon is supported by one of the most popular protocols, the iBeacon [5] protocol created by Apple. This is an Indoor Positioning System (IPS) that works on iOS 7+ devices and Android systems in Versions 4.3 and higher (with Bluetooth >4.0). This technology allows the emission of push notifications to the mentioned devices whenever they are in a nearby radius. iBeacon devices mainly have four layers of information corresponding to:
* Universally Unique Identifier (UUID): The UUID is the standard identification system that allows a unique number (or code) to be assigned to a device. It would be the equivalent of MAC addresses. * Major and Minor: Major and Minor are numerical type values that are assigned to iBeacons in order to identify them more accurately than using the UUID field alone. Minor and Major are integers between zero and 65,535. * Payload: The payload is the load that each beacon emits. In the case of iBeacon, it emits a URL address that is the one that will be used later to download the content of a POI using the Internet. * Radius Network AltBeacon: This beacon is supported by the AltBeacon protocol created by Radius Networks, a company that tries to imitate the iBeacon protocol, but offering the code for free and increasing the number of bytes available for the user from 25-28 (compared to the 20-27 of iBeacon).