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In this paper we consider call admission control in cellular environment for data sessions and voice calls of high priority. A cell is divided into two zones with different average signal to noise ratio, and each zone uses its own modulation and coding. A dynamic resource allocation scheme is further considered, which allows communication systems to utilize their resources more efficiently. All the...
This paper proposes a framework for admission control of pre-stored video streams, which provide deterministic guarantees on the maximum delay of video traffic and increase the network resource utilization. The framework take advantage of the fact that video streams can be processed off-line to calculate the space and time parameters in order to estimate its effective bandwidth under the many sources...
This paper proposes a novel admission control architecture for video-on-demand servers, which provide deterministic guarantees on the maximum delay of video traffic and increase the network resource utilization. The framework take advantage of the fact that stored video streams can be processed off-line to calculate the space and time parameters in order to estimate its effective bandwidth under the...
High concentration of users in a cell of a wireless LAN leads to an unsustainable traffic load at the access point (AP). An unsuitable solution to the problem will cause poor connectivity for users, severe performance degradation, and possible collapse of the wireless LAN. In this paper, we present a scheduler based on queue length at the AP and a congestion control scheme based on the channel utilization...
In order to support quality of service (QoS) for realtime traffic in wireless local area networks (WLANs), an efficient admission control scheme called EACS is proposed. According to the QoS requests of existing connections in access point's polling table, EACS decides the maximum contention resolution time which can meet the existing requirements. Then, EACS determines the maximum number of stations...
Carrier sense multiple access with enhanced collision avoidance (CSMA/ECA) is a simple MAC protocol for wireless local area networks that significantly outperforms CSMA/CA. This paper addresses traffic prioritization in CSMA/ECA using different minimum contention windows for different traffic classes. The conditions under which the collision-free operation is possible are presented and expressions...
In wireless sensor networks (WSNs), timeliness is one of the most challenging problems for critical applications. Caccamo et al. designed a collision-free real-time MAC protocol for sensor networks by adopting the "cellular structure" in traditional telecommunication networks. They assumed that sensors are organized into many rigid hexagon cells and a router node is at the center of each...
Nowadays, wireless network users demand support for different types of traffic combined with longer battery lifetime for their mobile devices. This work proposes a new medium control for wireless LANs as an alternative to the HCF (hybrid coordination function) scheme defined by the IEEE 802.11e workgroup. LEPOHA (low energy priority oriented hybrid access) is a complete medium access mechanism, it...
The IEEE 802.11e WLAN supports prioritized Quality of Services (QoSs), but it needs additional mechanisms to support also the strict QoS required by real-time services. It has been shown that best performance is achieved when the WLAN is unsaturated. Therefore, a call admission control scheme is required to maintain the WLAN working in the unsaturated case. In this paper, we propose an analytical...
A total QoS solution including dynamic call admission control scheme and bandwidth allocation algorithm is proposed for IEEE 802.16e mobile WiMAX. In this paper, the relationship between the channel utilization, the dropping and blocking probability versus traffic loads are investigated. The proposed WiMAX scheme supports voice, data and multimedia services with differentiated QoS.
In this paper, a QoS solution incorporating a dynamic call admission control scheme and a bandwidth allocation algorithm is proposed for WIMAX mobile application. The relationship between the channel utilization, the dropping and blocking probability versus traffic loads has been investigated. The proposed solution supports voice, data and multimedia services with differentiated QoS.
In this paper, we present an exact analysis method for an integrated voice and data wireless LAN with non-persistent carrier sense multiple access with collision avoidance (CSMA/CA) protocol to exactly derive the moment generating function (m.g.f.) of the data packet delay. The system model consists of a finite number of users to share a common channel. Each user can be a source of both voice traffic...
The traditional TCP congestion control mechanism encounters a number of new problems and suffers a poor performance when the IEEE 802.11 MAC protocol is used in multihop ad hoc networks. Many of the problems result from medium contention at the MAC layer. In this paper, we first illustrate that severe medium contention and congestion are intimately coupled, and TCP's congestion control algorithm becomes...
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