Scope and Motivation
The wide dissemination of mobile devices such as smartphones or tablets has created opportunities for the development of new technologies and services. The communication and computing capabilities of these mobile devices lead to the advent of new applications that, in turn, increase the user’s demand for broadband Internet access anywhere, anytime. These factors are pushing to the limits the capacity of existing cellular networks.
This problem is exacerbated in scenarios of crowded public events, such as fun parks, fairs or large festivals, where a large number of people are located in small areas for short periods of time, and where it is not feasible to have a permanent wireless access infrastructure to accommodate a sporadic bandwidth demand by the mobile terminals. These scenarios are characterized by a high density of mobile terminals, with tens of thousands of people and, at least, one terminal per user. Most of the users in these events want Internet access with high requirements of bitrate and delay, so they can use applications which include the exchange of high quality media content to social networks or streaming services. Moreover, in an open air event the spectators are not fixed (unlike in a sports stadium) and there may be crowd movements which, in turn, can lead to a traffic demand that depends on the area and the time of the day. These characteristics make crowded public events very challenging for communications networks. Cellular networks consisting of large cells do not have enough capacity to provide broadband Internet in areas with high density of users. Wi-Fi Access Points (AP) are a potential solution for this problem but each AP is unable to cover a large area or to serve a large number of users. A WiFi based solution may require the temporary deployment of tens of APs to provide adequate capacity, but there are problems related to the deployment of this number of APs. For instance, in a music festival it may be difficult to deploy APs in the middle of the crowd since they may interfere with the field of view of the crowd and the quality of the show. In addition, APs may have low workload during a period and excess of users during other periods making the cost of the infrastructure very high if we consider the average or maximum capacity requirements. Moreover, a fixed AP cannot follow the random movement of the crowd when considering mobile users.
More recently, Unmanned Aerial Vehicles (UAVs) emerged as a promising technology to provide communications in remote areas without network infrastructure. UAVs are versatile and secure aircrafts that can be operated autonomously by a control mechanism or remotely by a pilot, which makes them useful to operate in areas of difficult access. Most existing solutions use a single UAV to act as a relay between two networks. The advent of smaller, low-cost UAVs and the development of suitable control algorithms, has enabled the implementation of teams of UAVs. The capability to operate in any place and their mobility make UAVs useful devices to use in open air crowded places.
The WISE project aims to develop a new communications solution based on the concept Flying Backhaul Mesh Network (FBMN). At the core of the FBMN concept is the usage of Unmanned Aerial Vehicles (UAVs), which will carry on-board Mesh Access Points (MAPs) and will form a mobile and physically reconfigurable wireless backhaul mesh network composed of Flying MAP (FMAP). This network will be self-organised and the FMAPs will position themselves according to the data traffic generated by the mobile terminals and the need to relay the traffic towards the Internet. Small Wi-Fi cells will be deployed where and when they are needed, and will have the ability to follow their users.