The purpose of this study was to investigate left-ventricular function during strenuous exercise with the self-contained breathing apparatus (SCBA). With the use of two-dimensional echocardiography, images of the left ventricle (LV) were acquired during sustained exercise (3 x 10 min) under two conditions: 1) SCBA, or 2) low resistance breathing valve. Twenty healthy men volunteered for the stu...

Quality of Service (QoS) is the ability to guarantee a certain level of performance to a data flow ie., guaranteeing required bit rate, delay, etc. IEEE 802.11 a/b/g networks do not provide QoS differentiation among multimedia traffic. QoS provisioning is one of the essential features in IEEE 802.11e. It uses Enhanced Distributed Channel Access (EDCA) which is a contention-based channel access ...

Wireless information networks satisfy the users’ desirable requirements for mobility and relocation and thus have experienced tremendous growth in recent years. The Enhanced Distributed Channel Access (EDCA) is a promising Medium Access Control (MAC) protocol for provisioning of Quality-of-Service (QoS) in Wireless Local Area Networks (WLANs). This protocol specifies three important QoS schemes...

The IEEE 802.11 MAC protocol cannot support quality of service (QoS) requirements. In order to provide QoS in the IEEE 802.11 MAC protocol, the IEEE 802.11e has been standardized. These standards provide multiple transmission rates, which can be changed dynamically according to the channel condition. When using multiple transmission rates, the capacity of wireless LAN improves, but the performa...

The IEEE 802.11e Enhanced Distributed Channel Access (EDCA) protocol has been proposed for provisioning of differentiated Quality-of-Service (QoS) between various Access Categories (ACs), i.e., inter-AC QoS, in Wireless Local Area Networks (WLANs). However, the EDCA lacks the support of the intra-AC QoS provisioning, which is indispensable in the practical WLANs since the network loads are alwa...

The flexibility of wireless connectivity is appealing in the context of real-time industrial networks. This paper discusses the use of wireless communication protocols to interconnect remotely located fieldbuses. The focus of this paper is to analyze the feasibility and design issues related to this type of hybrid real-time network architecture. Investigations are presented by addressing an int...

Analytical modeling and performance study of the Enhanced Distributed Channel Access (EDCA) function of the IEEE 802.11e standard has been the topic of various works available in the literature. Nevertheless, the Packet Fragmentation (PF) conceived by the IEEE 802.11 work group for decreasing the effect of noise-related losses on the performances of IEEE 802.11 networks, has not at all been tak...

EDCA (Enhanced Distributed Channel Access), developed for providing service differentiation in wireless LANs, has become a MAC standard in IEEE 80.2.11e. However, unexpected packet delay due to collisions and retransmissions may occur when the wireless LAN becomes congested. To support the increasing demand of delay-sensitive multimedia applications, this paper presents a modified EDCA with dyn...