Quality Of Service For Multimedia Applications Research Articles

Bandwidth-Adaptive Scheduling for Quality of Service Enhancement of Real-Time Multimedia Applications in Network Processor Based Router

Problem statement: An explosive growth of multimedia applications in internet has stressed the performance of routers. Hence managing Quality of Service (QoS) enhancement of real-time multimedia applications over IP is a significant and demanding challenge. Approach: To address this issue, Bandwidth Adaptive Stratified Round Robin (BASRR) packet scheduling algorithm has been proposed in this paper for enhancing quality of service of real-time multimedia applications. Embedded Network Processors (NP) have recently emerged with flexibility and speed to reduce the stress of the router by effectively processing the packets. The main objective of this study was to implement the proposed packet scheduling algorithm in a Network Processor (NP) based router for enhancing quality of service of real-time multimedia applications Results: The effectiveness of the BASRR algorithm has been verified by simulations using Intel’s IXP 2400 network processor. The results show that BASRR achieves about 71.25% reduction in jitter compared to SRR when the traffic has uniform distribution of real-time flows and non real-time flows. The reduction in average queuing delay is about 30% compared to SRR for all the types of traffic. Conclusion: The QoS for multimedia applications has been achieved by the proposed non-preemptive Bandwidth Adaptive Stratified Round Robin (BASRR) scheduling algorithm and outperforms the three well-known scheduling algorithms including DRR, WDRR and SRR. The results showed that BASRR is efficient with per packet complexity of O(1) and provides better fairness and reduced delay.

Admission control scheme based on priority access for wireless LANs

In order to support the quality of service (QoS) requirements at the medium access control (MAC) layer, the enhanced distributed channel access (EDCA) has been developed in IEEE 802.11e standard. However, it cannot guarantee the stringent real-time constraints of multimedia applications such as voice and video without an efficient method of controlling network loads. In this paper, we propose a measurement-based admission control scheme, which is made up of two parts: priority access and admission control. First, in order to measure the channel status per traffic type, we propose a priority access mechanism in which each priority traffic is distinguished by a busy tone, and separately performs its own packet transmission operation. Then, admission control mechanism protects existing flows from new ones, and maintains the QoS of the admitted flows based on the measured channel status information. Performance of the proposed scheme is evaluated by simulation. Our results show that the proposed scheme is very effective in guaranteeing the QoS of multimedia applications as well as in avoiding the performance starvation of low priority traffics.

Proactive estimation of the video streaming reception quality in WiFi networks using a cross-layer technique

The quality of service (QoS) in a Wireless Fidelity (WiFi) network can not be guaranteed due to intermittent disconnections, interferences and so forth because they reduce considerably the necessary QoS for multimedia applications. For that reason it is essential a software as the one we present in this paper that evaluates if there are the appropriate conditions to receive the streaming measuring the congestion, radio coverage, throughput, lost and received packets rate, and so on. Our software makes a proactive estimation using a bottom-up cross-layer technique measuring physical level parameters, Round Trip Time (RTT) and getting traffic statistics for the overall WiFi network and for each ongoing Real Time Streaming Protocol/Real Time Protocol (RTSP/RTP) streaming session. Experimental results show a high percentage of good decisions of the software to detect the wireless channel degradation and its recovery.

A Priority Queuing Model for HCF Controlled Channel Access (HCCA) in Wireless LANs

Recently, there has been a rapid growing interest in new applications requiring quality of service (QoS) guarantees through wireless local area networks (WLAN). These demands have led to the introduction of new 802.11 standard series to enhance access medium supporting QoS for multimedia applications. However, some applications such as variable bit rate (VBR) traffic address some challenges in the hybrid coordination function (HCF) nominated to provide QoS. This paper presents a novel priority queuing model to analyze a medium access in the HCF controlled channel access (HCCA) mode. This model makes use of a MAP (Markovian Arrival Process)/PH (Phase Type)/1 queue with two types of jobs which are suitable to support VBR traffic. Using a MAP for traffic arrival process and PH distribution for service process, the inclusion of vacation period makes our analysis very general and comprehensive to support various types of practical traffic streams. The proposed priority queuing model is very useful to evaluate and enhance the performance of the scheduler and the admission controller in the HCCA mechanism.

A method to efficiently integrate Internet Telephony call signaling with dynamic resource negotiation

Internet Telephony imposes Quality of Service (QoS) requirements in terms of delay, jitter and loss ratio to provide reliable, high-quality multimedia services. While the Internet has historically offered a best effort service, it is hard to satisfy the required QoS of multimedia applications. In order to provide a tight QoS guarantee to telephony services, priority must be offered to real-time flows. Dynamic resource negotiations are required at the beginning of sessions besides long term service contracts. Most of the researchers propose to integrate call signaling with resource negotiation in a sequential manner [G. Camarillo, W. Marshall, J. Rosenberg, Integration of Resource Management and SIP, IETF RFC 3312, October 2002; P. Goyal et al., Integration of call signaling and resource management for IP telephony. IEEE Network, 13(3) (1999) 24-32; H. Schulzrinne, J. Rosenberg, J. Lennox, Interaction of call setup and resource reservation protocols in Internet Telephony. Technical Report, Columbia University and Bell Laboratories, June, 1999. Available from: http:// www.cs.columbia.edu/~hgs/sip/drafts/resource.pdf]. This method can provide QoS at the highest level, but it results in high call setup delay and high probability of connection failure. Parallel integration is an alternative method that can mitigate these drawbacks. In this paper, we proposed a detail solution based on the parallel approach to establish resource negotiation simultaneously with call signaling. This approach can apply to different QoS models and mechanisms such as Integrated Services (IntServ), Differentiated Services (DiffServ) and Multi-Protocol Label Switching (MPLS). This paper presents the architecture and system design of the parallel signaling approach. Threshold quality control scheme is applied to guarantee that the service is above the acceptable level before a telephone session begins.