Using cooperative MIMO techniques and UAV relay networks to support connectivity in sparse Wireless Sensor Networks

One possible way to define the end of lifetime for a Wireless Sensor Network (WSN) is to set a threshold for the number of disconnections among the sensor nodes so that above this level the WSN becomes unable to provide the quality of services required by the users or even totally loses its ability to provide any service at all. Disconnections isolate sensors or group of sensors which cannot deliver their acquired data, thus constituting a sparse nonfunctional WSN, although some of its isolated or grouped sensors remain operational. A possible way to overcome such a problem is to provide an alternative reliable connection via other types of nodes to support the communication among isolated parts of a disconnected network. This paper proposes the use of cooperative multiple input multiple output (MIMO) techniques to support communication among static sensors in a sparse WSN and a relay network composed of Unmanned Aerial Vehicles (UAVs) keeping the WSN connected, thus extending its lifetime. Simulations of the proposed approach are performed and the acquired results highlight the benefits of this proposal.