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In recent years, video streaming traffic has increased exponentially over the Internet. This can be observed through the emergence of various video on demand sites such as Netflix, Amazon movies and others. In parallel, IEEE 802.11 (WiFi) technology has been deployed extensively from home to public areas. Although significant research has been done to address issues on video streaming through WiFi...
This paper's main objective is to analyze the quality of service using the network simulator NS2, in an infrastructure WLAN for voice, video, and data with IEEE 802.11g and IEEE 802.11e standards by access types DCF (Distributed Coordination Function), Enhanced Distributed Channel Access (EDCA) and Hybrid Coordination Function Controlled Channel Access (HCCA). For this purpose, comparative studies...
The performance of IEEE 802.11e enhanced distributed channel access (EDCA) mechanism effects by the network loads. It is observed that when the number of users increases in each access category, the delay significantly increased in EDCA algorithm. The performance improvement in EDCA algorithm in fluctuating network load is a challenging task. To improve the performance of EDCA algorithm for delay...
In Recent times, real time applications are increasing gradually which have specific Quality of Service (QoS) requirements. IEEE 802.11e is aimed to provide such QoS. 802.11e uses traffics differentiation among flows using a parameter set. The flows are admitted using their priority. The voice and video flows are admitted in most of the times due to their higher priority. This causes the increase...
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...
Multimedia applications such as video streaming have posed challenges over the wireless networks. A selective mapping approach was proposed in this paper to address the quality of delay-sensitive video transmitted over 802.11e EDCA wireless LAN. This cross-layer design takes into account the importance of packets and end-to-end delay requirements. Packets of high importance will be assigned to virtual...
This work proposes a novel Delay-aware Packet Prioritisation Mechanism (DPPM) to uniformly distribute the Quality of Service (QoS) level across all Voice Over IP (VoIP) calls in a Wireless Mesh Network (WMN). The method prioritises VoIP packets based on the amount of queueing delay that has been accumulated across multiple hops within the WMN. The accumulated queueing delay is piggybacked over every...
The difference in transmission performance arises among child cluster heads (CCHs) on inter-cluster communications in cluster-based wireless sensor networks (WSNs) with spatial non-uniform traffic because several CCHs with different traffic loads communicate to their parent cluster head on shared communication channel. Against this problem this paper proposes traffic adaptive backoff control mechanism...
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...
In this paper, we evaluate the saturation throughput and saturation delay with direct/cooperative transmission strategies. Moreover, the cost function is introduced to tradeoff the system performance to determine the optimal strategy for adopting the cooperative transmission, and then we extend the model to support applications with quality of service (QoS) requirements. In order to improve the efficiency,...
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...
Voice capacity over wireless local area networks (WLANs) can be increased by the statistical multiplexing among on/off voice calls. However, in previously proposed schemes, the admitted voice calls that transit from silence state to talkspurt state are mixed up with the new voice calls to contend for the channel. The increase in the traffic load of new voice users could degrade the performance of...
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...
Multimedia traffic support over Wireless Local Area Networks (WLANs) witnessed a huge demand recently with market fusion toward personal smart digital devices. Bandwidth utilization, minimum delay and jitter are some of the critical requirements to provide real-time applications with good quality of service (QoS) level. In this paper, we evaluate the performance of the traditional IEEE 802.11 standard...
The IEEE 802.11e standard is a complement to the IEEE 802.11 family that provides Quality of Service (QOS) in wireless networks at MAC layer level. For the multimedia applications such as video MPEG4, IEEE 802.11e provides a contention based MAC function EDCF (Enhanced Distributed Coordination Function). EDCF offers differentiated services for different type of traffic flows. In this paper the IEEE...
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...
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