PDAC: um protocolo de alocação dinâmica de canais para ambientes médicos

Abstract

The increased use of wireless networks and the constant miniaturization of devices allowed the development of wireless body area networks (WBANs). In these networks, diverse sensors are positioned on the user's skin. The sensors in a WBAN gather data from heart rate, body temperature or even a cardiogram. Through the use of WBAN, patients will have a noninvasive monitoring system, which hardly affects their mobility. These characteristics, however, create several problems. By transmitting critical informa-tion, these data are quite sensitive to high latency and packet loss. The loss of vital data can lead to serious consequences in the users' life and, in extreme cases, leading to death. The inherent characteristics of wireless communication are a major issue for WBANs. With their popularization and high mobility, it is reasonable to consider the existence of very dense medical environments, where two or more WBANs can simultaneously use the same wireless communication channel. This situation can produce interference, leading to a bigger number of retransmissions and packet losses, and consequently increasing latency. Therefore, this master thesis presents the PDAC (Protocol for Dynamic Channel AlloCation), a protocol for dynamic channel allocation, that is aware of the requirements of medical applications. PDAC offers a solution to reduce interference between WBANs by taking advantage of the architecture of a hospital environment. Using PDAC, several base stations work collaboratively to meet medical application requirements. For an interference-free allocation, PDAC is inspired by a greedy solution of a graph colouring problem, preventing neighbouring base stations of using the same channel simultaneously. In addition, PDAC offers through the channel bonding, a better goodput. The evaluation PDAC was performed in two phases: by means of simulations and formal analysis. Simulation results indicate that PDAC is able to increase goodput by 30% (on average) and reduce latency by 40% (on average) when compared to the literature. The formal verification, in turn, shows that the protocol is consistent and also satisfies all verified security properties.