An analysis of voice over internet protocol in wireless mesh networks

Magister Scientiae - MScThis thesis presents an analysis of the impact of node mobility on the quality of service for voice over Internet Protocol in wireless mesh networks. Voice traffic was simulated on such a mesh network to analyze the following performance metrics: delay, jitter, packet loss and throughput. Wireless mesh networks present interesting characteristics such as multi-hop routing, node mobility, and variable coverage that can impact on quality of service. A reasonable deployment scenario for a small organizational network, for either urban or rural deployment, is considered with three wireless mesh network scenarios, each with 26 mesh nodes. In the first scenario, all mesh nodes are stationary. In the second scenario, 10 nodes are mobile and 16 nodes are stationary. Finally, in the third scenario, all mesh nodes are mobile. The mesh nodes are simulated to move at a walking speed of 1.3m per second. The results show that node mobility can increase packet loss, delay, and jitter. However, the results also show that wireless mesh networks can provide acceptable quality of service, providing that there is little or no background traffic generated by other applications. In particular, the results demonstrate that jitter across all scenarios remains within humanacceptable tolerances. It is therefore recommended that voice over Internet Protocol implementations on wireless mesh networks with background traffic be supported by quality of service standards; otherwise they can lead to service delivery failures. On the other hand, voice-only esh networks, even with mobile nodes, offer an attractive alternative voice over Internet Protocol platform.South Afric

Performance Analysis of IPv6 Transition Mechanisms over MPLS

 Exhaustion of current version of Internet Protocol version 4 (IPv4) addresses initiated development of next-generation Internet Protocol version 6 (IPv6). IPv6 is acknowledged to provide more address space, better address design, and greater security; however, IPv6 and IPv4 are not fully compatible. For the two protocols to coexist, various IPv6 transition mechanisms have been developed. This research will analyze a series of IPv6 transition mechanisms over the Multiprotocol Label Switching (MPLS) backbone using a simulation tool (OPNET) and will evaluate and compare their performances. The analysis will include comparing the end-to-end delay, jitter, and throughput performance metrics using tunneling mechanisms, specifically Manual Tunnel, Generic Routing Encapsulation (GRE) Tunnel, Automatic IPv4-Compatible Tunnel, and 6to4 Tunnel between Customer Edge (CE)-to-CE routers and between Provider Edge (PE)-to-PE routers. The results are then compared against 6PE, Native IPv6, and Dual Stack, all using the MPLS backbone. The traffic generated for this comparison are database access, email, File Transfer, File Print, Telnet, Video Conferencing over IP, Voice over IP, Web Browsing, and Remote Login. A statistical analysis is performed to compare the performance metrics of these mechanisms to evaluate any statistically-significant differences among them. The main objective of this research is to rank the aforementioned IPv6 transition mechanism and identify the superior mechanism(s) that offer lowest delay, lowest jitter, and highest throughput

A Utility-based QoS Model for Emerging Multimedia Applications

Existing network QoS models do not sufficiently reflect the challenges faced by high-throughput, always-on, inelastic multimedia applications. In this paper, a utility-based QoS model is proposed as a user layer extension to existing communication QoS models to better assess the requirements of multimedia applications and manage the QoS provisioning of multimedia flows. Network impairment utility functions are derived from user experiments and combined to application utility functions to evaluate the application quality. Simulation is used to demonstrate the validity of the proposed QoS model

On the quality of VoIP with DCCP for satellite communications

We present experimental results for the performance of selected voice codecs using DCCP with CCID4 congestion control over a satellite link. We evaluate the performance of both constant and variable data rate speech codecs for a number of simultaneous calls using the ITU E-model. We analyse the sources of packet losses and additionally analyse the effect of jitter which is one of the crucial parameters contributing to VoIP quality and has, to the best of our knowledge, not been considered previously in the published DCCP performance results. We propose modifications to the CCID4 algorithm and demonstrate how these improve the VoIP performance, without the need for additional link information other than what is already monitored by CCID4. We also demonstrate the fairness of the proposed modifications to other flows. Although the recently adopted changes to TFRC specification alleviate some of the performance issues for VoIP on satellite links, we argue that the characteristics of commercial satellite links necessitate consideration of further improvements. We identify the additional benefit of DCCP when used in VoIP admission control mechanisms and draw conclusions about the advantages and disadvantages of the proposed DCCP/CCID4 congestion control mechanism for use with VoIP applications