HM4All: A vital signs monitoring system based in spatially distributed ZigBee networks

Helena Fernandez-Lopez, Jose A. Afonso, J. H. Correia, Ricardo Simoes
2010 Proceedings of the 4th International ICST Conference on Pervasive Computing Technologies for Healthcare  
Low power consumption and small footprint make ZigBee based devices well suited for personal healthcare applications, being a promising alternative to general care patient monitoring. However, their use in a health care facility to monitor several mobile patients poses several difficulties, mainly because this protocol was primarily designed to operate in low data rate scenarios. This paper introduces HM4AII, a remote vital signs monitoring system, and presents a prototype system being deployed
more » ... in a hospital internment floor. Its architecture, original network topology, software applications and wireless sensors are described. they must be powered by batteries. On the other hand, the reliance on these systems depends on the satisfaction of quality of service (QoS) requirements, such as sustainable throughput, small delay and high reliability. The main difficulty arises from the fact that some sensors must be sampled quite often, generating a large amount of data and, consequently, requiring the network to operate under high load, which is not common in typical WSN scenarios. Therefore, a careful network design is required, as will be further discussed, to assure that QoS requirements are achieved. The usage of standard-based communication technologies with healthcare oriented profiles can offer several benefits, such as: • Standard protocol stacks implementations are reliable and can considerably reduce development costs. • Standard-based radios and integrated communication modules are cheaper than customized solutions. • Medical sensors from a variety of manufacturers can coexist and exchange information. In this paper, we introduce HM4All (Health Monitor for All), a prototype vital signs monitoring system that will be deployed in an internment floor of a private hospital in Portugal. HM4All is based on WSN technologies and standard based protocols, and was designed to allow remote monitoring of ECG (electrocardiography), Sp02 (oxygen saturation in the blood), and skin temperature. Out-patients recovering at home can also be monitored by specialized healthcare providers in the hospital. Additionally, we have developed the infrastructure necessary to monitor patients anywhere using a personal digital assistant (PDA). The paper is organized as follows. In the next section, we present a short discussion about the IEEE 802.15.4 and ZigBee protocols. In Section III, we introduce the overall system architecture and the network topology adopted. Section IV presents the prototype system being deployed, including the specific topology, and the wireless sensors and software applications developed for this work. In Section V, we discuss some results already achieved. In the next section, we present the related work and, finally, in the last section, the conclusions are presented. AND ZIG BEE PROTOCOLS HM4AII WSN is based on the 802.15.4 [4] and ZigBee [5] protocols, which provide the network infrastructure required for WSN applications. The 802.15.4 standard was developed by the IEEE, and defines the physical (PHY) and medium access (MAC) layers. The PHY layer is responsible for data transmission and reception and defines three possible frequency bands. The higher frequency band ranges from 2400 MHz to 2483.5 MHz, divided into sixteen 2 MHz channels that operate at a rate of 250 kbps. The MAC layer handles the access to the physical radio channel using a contention-based CSMA-CA algorithm. The ZigBee protocol, developed by the ZigBee Alliance, stands on top of the 802.15.4 and defines the network and application layers. Both protocols are intended for applications that require long battery life, low cost, small footprint, and mesh networking to support communication between large numbers of devices in an interoperable and multi-application
doi:10.4108/icst.pervasivehealth2010.8836 dblp:conf/ph/Fernandez-LopezACS10 fatcat:rq674uh7pndlndmayacfks3sxy