Arlen Nascimento

Can I add a secure VoIP call

Voice over IP is a major trend in applications for wireless networks, but even so it is not immune to the risks usually related with IP networks. Proposed solutions for VoIP security are already in the market, but these solutions must take into account the real-time constraint of voice service and their mechanisms should address possible attacks and overhead associated with it. One of these solutions is to use IETF IPSec to guarantee confidentiality in order to address security design holes of wireless VoIP networks. This article performs an experimental comparison of the impact of encryption mechanisms on voice speech quality in widely deployed wireless technologies: 802.11 and Bluetooth. Evaluates the upper bound on number of simultaneous VoIP calls which can be placed in a single cell of both networks when security is applied and uses the computational model E-Model to assess quantitatively the quality of service

Impact evaluation of radio propagation models on performance parameters of application layer in Wireless Mesh Backbone simulation

In this paper we propose a VoIP study case to evaluate the impact of different radio propagation models on performance parameters of application layer in simulation studies of Wireless Mesh Backbones. For each presented model, we carried out experiments taking into account the credibility aspects suggested by simulation theory of stochastic processes. Results showed that, for the same scenario, using different propagation models, voice speech quality can switch from acceptable to unacceptable.

Management of VoWLAN security parameters using a QoS tool

Voice over IP is becoming an important application for wireless networks based in the IEEE 802.11 standard, but many problems must be addressed for the success of this combination, such as providing high number of connections with acceptable speech quality and minimal level of security. This paper presents the results related with a QoS evaluation tool implementation and its utilization in a VoWLAN environment in order to evaluate the performance of the VoIP system with the IPSec used to guarantee confidentiality. In addition, we demonstrate how this QoS tool can be deployed inside the network operation to assist network nodes on selecting more accurate IPSec parameters to reduce the security impact on the real-time traffic

Influence of Routing Protocol on VoIP Quality Performance in Wireless Mesh Backbone

In this paper we focus on the following question: how routing protocols, working under different channel conditions, can influence the human perceived quality of VoIP calls in a wireless mesh backbone? In order to respond this question, we propose a study case where we analyze two routing approaches in a 802.11 wireless mesh backbone, namely, reactive AODV and proactive OLSR. We calculated the voice speech quality by making use of a reviewed version of ITU-T E-model proposed in previous work. Results obtained from highly credible stochastic simulation environment, also described in this paper, showed that AODV performs better in very hostile mediums while OLSR presents better results when more friendly mediums take place.

Comparative analysis of routing protocols for VoIP in a Wireless Mesh Backbone: a user perspective

In this work we select AODV, OLSR and HWMP routing protocols and focus on how they can affect the Quality of user Experience (QoE) with respect to VoIP on a wireless backbone. We calculated QoE by using a reviewed version of the E-model. Since that parameter is strongly correlated with some stochastic network variables it presents stochastic behaviour too. So, we discuss important issues needed to estimate QoE based parameters in a trusty way. Results showed that the average QoE kept acceptable only under AODV routing as the number of VoIP traffic was increased in the network.