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The ability to provide Quality of Service in Wi-Fi networks to a considerable degree depends on a used channel access method. A number of access methods allow a Wi-Fi station to preliminarily reserve a set of time intervals inside which transmissions are protected from interference. However, fixed parameters assigned to such reservations make them not so flexible as needed for serving Variable Bit...
We propose a QoS supporting ad hoc network scheme which employs a hybrid approach utilizing both TDMA and 802.11 DCF and present performance evaluation results of the scheme. In the scheme, TDMA period provides contention free transmissions for QoS flows, and DCF period is used to provide contention-based access for best effort or low priority flows. We evaluate the proposed scheme for various numbers...
The Voice over IP (VoIP) service demands high priority over other services and applications. Some constrains are associated with this real-time service, such as delay and throughput which need to be addressed before delivering to the customer. The mobility in IP networks is a demand that facilitates IP applications and services, especially in wireless networks. This paper demonstrates the performance...
IEEE 802.11e is an extension for media access control in wireless network. It is used for different Quality of Service requirement for different transmission application. But it assumes that all terminals operate in the same transmission speed. But when terminals use different transmission speeds, the access mechanism, EDCA, can not perform to its design purposes. Because the parameters designed for...
We propose a QoS supporting ad hoc network protocol which employs a hybrid approach utilizing both TDMA and 802.11 DCF. TDMA period provides contention free transmissions for QoS flows, and DCF period is used to provide contention-based access for best effort or low priority flows. TDMA time slots are assigned on admission basis in a distributed manner by utilizing network routing information and...
WiFi-enabled mobile devices such as smartphones and tablets are being increasingly used by both personal and business users for Voice over IP (VoIP) communications, while also supporting conventional data applications such as email, file transfer and web access. Previous research has shown that time synchronized endpoints can provide better QoS by utilizing the Real-time Transport Control Protocol...
In the existing IEEE 802.11e standard, all VoIP sessions contend within the same prioritization Access Category (AC), despite potentially having very different, and varying one-way (M2E - Mouth to Ear) delays. In this paper we show how VoIP endpoints that are time synchronized can help optimize 802.11e EDCA in order to prioritize VoIP sessions that have relatively large M2E delays and thus distinguish...
WiFi-enabled mobile handheld devices are being increasingly used for Voice over IP (VoIP) as well as supporting conventional data applications such as email, file transfer and web access. Wireless LANs (WLANs) are thus increasingly required to support Quality of Service (QoS)-centric applications, which are delay sensitive and require a certain level of throughput. While 802.11e goes some way towards...
TCP, the facto standard used in today's Internet, has been found to perform poorly in Mobile Ad Hoc Networks (MANETs). This is exacerbated by contention with increasing UDP-based high priority multimedia traffic and the class differentiation introduced in current QoS protocols, which results into TCP starvation and increased spurious timeouts. In this paper, we propose a cross-layer TCP enhancement...
With the emerging IEEE 802.11n standard, the WLAN is poised as a promising ubiquitous networking technology to support multimedia applications where providing QoS becomes imperative. However, the 802.11 WLAN is not designed to support delay sensitive traffic. This problem is magnified during a handover and typically results in excessive handover latency and packet loss. In addition, a 802.11 WLAN...
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