Recently, the research regarding wireless applications in e-Health services has increased. The use of wireless technology has an important influence on different e-Health applications, because the main aim in the healthcare networks is the delivery of accurate medical information anytime and anywhere. Simple communications, fast delivery of medical information, reducing treatment cost and reducing the medical workers error rate, are the main benefits of using wireless technologies in e-Health applications. But on the other hand, the use of wireless technologies causes the electromagnetic interference (EMI) problem. The main effects of the interference are automatic shutdown, automatic restart and waveform distortion of sensitive medical devices that can imperil patients who are using those devices. The most critical issues in designing wireless networks for e-Health environments such as a hospital are how to design an effective network to provide guaranteed quality of service (QoS) and to consider the EMI problem. Although power management and reducing the transmission power is an effective method to avoid the EMI, but it causes the number of successful message deliveries to the AP to decrease, and hence, the QoS requirements cannot be met. In this work, we first introduce QoS requirements in different medical data transmissions and then, investigate two approaches to avoid EMI effects in sensitive healthcare environments such as a hospital. In one approach, the controller must notify users of their maximum allowable transmission power based on the information about EMI immunity levels, status of sensitive medical devices and locations of users and sensitive medical devices. In upper bound power calculation per user, the controller must have accurate and perfect knowledge of the location and the status of all users in the network, and this information must be updated with every change in the network. However, these can increase the complexity of the controller in the network. To reduce the complexity of the controller in the first approach, the hospital environment is sectored into areas and the maximum allowable power for each area is calculated. We then compare interference and outage probabilities for proposed approaches. Results show that by considering network parameters, the interference problem can be alleviated with different arrival probabilities. Power management methods can control and avoid EMI problem, but it can increase the number of unsuccessful message deliveries. To reduce the outage probability in aforementioned scenarios, the advantages of relay station placement are investigated. We apply the genetic algorithm to find optimal positions for relays in the hospital. Performance evaluation results show that two-hop transfer of the information by using relay stations can reduce the outage probability; in addition, it can reduce the delay of high-priority users for low data size. We also investigate different relay assignment methods that can be used in healthcare environments. Keywords: Wireless Communication, EMI Problem, Power Management, Outage Reduction.
