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The IEEE 802.16(d) mesh mode is proposed for the next generation wireless mesh network. It specifies two mechanisms to schedule data transmission, namely centralized scheduling and distributed scheduling. In this paper, we evaluate the performance of VoIP traffic over an IEEE 802.16(d) mesh network using the distributed scheduling. The problems of the system in supporting voice traffic are identified...
Faced with intense competition, network service providers, supported by their respective network operations centers (NOCs), must ensure the best possible quality of service (QoS) and corresponding quality of experience (QoE) for end-users or face the loss of business. QoE represents the perception of quality experienced by end-users of a real-time system, such as VoIP. The QoE challenge becomes significant...
Emerging hybrid satellite communications and wireless network architectures support high bandwidth services and applications for tactical users. In this paper we propose a cross- layer design approach focusing on physical layer interaction on the application layer using an OPNET simulation environment. This paper studies the effect of fading on dynamic resource allocations and the impact of rain fading...
A voice conversation quality over IP networks is mainly affected by the end-to-end delay and the packet-loss rate. Various delay channel environment can cause the early/late arrival packet loss without actual packet loss. To overcome time-variant dynamics of transmission channels for IP telephone services, an adaptive playout-buffer scheduling is proposed. Previous playout-buffer schedulers focused...
This paper investigates QoE (quality of experience) of MVV (multi-view video) and audio transmission over IP networks. Unlike previous works that mainly discuss MVV transmission from aspects of video codecs, we study MVV and audio transmission under various IP traffic and delay conditions by experiment. We compare two schemes: a scheme that the user watches a single viewpoint, and the one that he/she...
The evolution of the Next Generation heterogeneous Networks relies on the improved services that these networks can provide to real-time applications. Applications running on wired networks work seamlessly with the Open Systems Interconnect (OSI) protocol stack implementation. Its modularity eases functionality and improves performance of these applications. However, the channel conditions for wireless...
Because of the best-effort service in Internet, direct routing path may not always meet the VoIP quality requirements. Thus, most VoIP systems such as SIP+P2P system use application-layer routing scheme to achieve better QoS performance, which is to use relay node to relay RTP stream from the source node to the destination node. The key of this scheme is how to lookup the appropriate relay nodes,...
Peer to peer (P2P) technology has dramatically transformed the landscape of the Internet traffic in recent years, which induces greatly attention and research on the deployment of P2P-based applications in heterogeneous networks. Indeed many obstacles still lie ahead. The main objective of this paper is to present a new method to deploy the most promising P2P technologies for heterogeneous networks...
For the limitation of the network resources, to support real-time service in mobile ad hoc networks is challenging, especially for the delay sensitive voice sessions. Firstly, the delay spike phenomenon is described and analyzed in detail in this paper. Then, to alleviate its impairment on the voice quality, based on the prediction of delay spikes, a new source rate adjusting mechanism is proposed,...
With the rapid development of the Internet, new technologies and applications are emerging. One of the important applications is voice over IP. Satellites are playing an important role to provide VoIP services with their global coverage and on-board processing ability over IP networks. Satellite network environment, generally characterized by large delay and erroneous link, is considered to be unfriendly...
Next generation mobile radio networks of IMT Advanced systems family will offer ubiquitous broadband high area coverage, at up to 1 GBit/s in cities and 100 MBit/s in rural areas and QoS support in terms of throughput and low delay. Candidate technologies like 3GPP-LTE, WiMAX, as well as the WINNER system design are based on OFDMA transmission for flexible radio resource allocation, scalable and adaptable...
This paper presents some experimental results about the robustness of a WiMAX system against interfering signals. In particular, this work presents a WiMAX performance comparison when two different types of interfering signals were generated: a continuous wave and a rectangular pulsed wave. Both of them were tuned at the same working frequency of the WiMAX system (i.e. 2.55 GHz). The former is typical...
User scheduling in future cellular networks is a complex and much-studied problem, further complicated in the increasingly relevant scenario of delay-sensitive VoIP applications. In such cases, the full buffer model that attempts to maximise the total sum-rate of the individual users does not adequately capture the satisfaction level of the users. As a result, fairness needs to be introduced and this...
The QoS of VoIP service in TDD-LTE uplink is subject to a series of restrictive factors, such as strong inter-cell interference, tight delay budget, less retransmission times, etc. This paper studies different scheduling and link adaptation schemes for VoIP users in TDD-LTE uplink and makes analysis of the corresponding simulation results. To further increase VoIP capacity, this paper proposes an...
In IEEE 802.16e OFDMA system, the system capacity for accommodating VoIP traffic with small-sized PDUs is severely reduced due to a large amount of signalling overhead. In order to mitigate this problem, the IEEE 802.16 maintenance group has recently proposed a persistent allocation scheme to increase the voice over IP (VoIP) system capacity. However, it is difficult to use the conventional modulation...
Fourth generation networks will almost invariably adopt OFDMA (orthogonal frequency division multiple access) and MIMO (multiple input-multiple output) technologies, in order to meet high data rate and quality of service (QoS) requirements. The worldwide interoperability for microwave access (WiMAX) MAC Layer, which is based on the IEEE 802.16 standard, is designed to support a variety of applications,...
As a result of its success, Wi-Fi has been promoted as an access technology to provide full internet connectivity in the municipal area. Supporting application QoS by managing resource provisioning is an important challenge for wireless network operators. This paper proposes a traffic engineering model for managing a Voice over Wi-Fi service in a municipal area with stationary and mobile clients....
In this study, we discussed with the protocol of SIP of VoIP. At first, using NS2 simulation software to analysis, then we researched those entities. Because of the impact of VoIP Quality of Service (QoS) as a major factor is the rate of packet loss. And of the human beings, the discontinuous voice caused by a small amount of packet loss can be tolerated. By using actual VoIP equipment, we observing...
We present a novel scalable call admission control for VoIP based on blocking probability calculation (BPC). Blocking probabilities were measured carrying VoIP for every router across the source-destination path. Ingress router selects the optimal path for the new request by calculating blocking probabilities across all source-destination paths. A simple algorithm design and evaluation results show...
In recent years, voice over Internet Protocol (VoIP) has gained much attention in wireless local area networks (WLANs). Although IEEE 802.11e has been standardized to provide voice traffic with quality of service (QoS) support, the voice quality will still be severely degraded with a large amount of best-effort traffic generated by distributed coordination function (DCF) or enhanced distributed channel...
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