Why do we need safety systems in communications?
The communication network that we use in a daily basis is designed to meet our requirements such as QoS, high data rates, specific coverage and minimum delay. However, what would happen in a special situation or emergency event where traffic increase dramatically? Commercial networks wouldn’t support this unusual massive demand. What would happen if core points of the communication architecture get damaged? An additional system to the terrestrial LTE and LTE-A is needed. In fact, governments, academia and industry are working together to bring solutions to these unexpected situations by exploiting the development of HetNets.
ABSOLUTE’s project is the main research activity that develops a hybrid land-and-air system which provides high data rates and low latency in and IP network specially designed to serve mass events and public safety.
Figure 1. ABSOLUTE’s project consortium
What is a Public Safety System?
The design and deployment of this type of network are determined by factors such as the size of the area selected, the minimum capacity provided, number of supported users and sites for the bases stations. In addition, the existing communication network needs to be taken into account to avoid frequency interference and to distribute the electrical power without compromising any deployed eNodeB. An additional requirement of these networks is the self-organization capabilities, as they need to be able to work in events where people can’t access to them. Among the main self-configuration capabilities, the base stations need to be able to detect the available bandwidth so the spectrum sensing is an important feature.
As mentioned earlier, the Public Safety Network is a terrestrial-air system (where users give priority to land-connections) and the main components of its architecture are shown in the following image:
Figure 2. ABSOLUTE Network Architecture
Some of the new elements in the network are:
- AeNodeB: these are the Aerial eNodeB that provide advanced mobility patterns, dynamic spectrum and it can rapidly deploy different services for many purposes. These are located on Low Altitude Platforms (LAPs) which are helium inflatable kites named Helikite (see Figure 3).
- PLMU: it’s the Portable Land Mobile Unit it’s and easy to deploy device that fills coverage gaps by integrating a WLAN router, a 4G eNodeB, a 3G nano cell, a TETRA base station and a WSN gateway.
- WSN: this is a Wireless Sensor Network.
- MM-UEs: Multimode User Equipments for first responders.
Figure 3. Network elements
As we have mentioned at the beginning of this article, commercial networks are not reliable during unexpected events or disasters, therefore the Safety Systems provide a resilient, scalable and flexible solution. The ABSOLUTE system provides a rapidly deploy network with large local coverage thanks to the combination of terrestrial, airborne and satellite systems and it is a temporary or complementary high capacity infrastructure.
This architecture is also used to enhance the capacity of massive events such as the Olympic Games by allowing operators to use its resources.
New developments are studied at the moment to improve the standalone eNodeB characteristics, the cooperative spectrum sensing capabilities and the satellite backhauling to be able to support the capacity and mobility requirements.
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