Avaliação das tecnologias ClientMatch e dos padrões IEEE 802.11k e 802.11r no suporte a mobilidade e tráfego de tempo real em redes WLAN

In recent years, we have observed an increase of use and evolution of the IEEE 802.11 based-networks. Currently, the University of Brasília (UnB) owns and operate a WLAN (Wireless Local Area Network) infrastructure to serve users of its campuses. Through this infrastructure, UnB is seeking alternatives to better serve its users, preferably without increasing its costs. An alternative is the implementation of voice over the wireless network of the Institution, where users utilize their mobile devices for communication while providing mobility. When using voice over wireless networks, parameters such as delay, delay variation and packet loss must comply with the recommendations for reasonable phone calls quality. Furthermore, providing mobility in IEEE 802.11 networks involves the transition of the mobile user between access points and this very process is one of the key factors of voice quality degradation. The UNB wireless networking solution encompasses technologies such as ClientMatch, IEEE 802.11r and 802.11k standards that assist the mobile user in the transition process. In this context, this work evaluates the impact of the ClientMatch technology, IEEE 802.11r and 802.11k standards in supporting mobility and voice traffic, while evaluating the audio quality, performance of the main QoS (Quality of Service) parameters in a VoIP network (Voice over IP). The conducted experiments showed that the ClientMatch – Sticky Client technology is not tailored for mobility support, presenting low rate of action, while the IEEE 802.11r and 802.11k technologies have not produced the expected results. Even with the low rates of operation of ClientMatch – Sticky Client technology and unexpected results of the solutions 802.11k and 802.11r, the UnB WLAN infrastructure provided good performance for voice traffic, even under moderate mobility, attaining acceptable levels of voice quality; nevertheless, the process of transition between access points, ClientMatch – Band Steering and the distance between access points may impact in the results. In addition to the experiments that seek to evaluate the impact of technology ClientMatch and IEEE 802.11r and 802.11k standards in supporting mobility and voice traffic, tests were performed with CODECs (Coder Decoder) by mobility of mobile client. The encoder – decoder G711 showed the best results in the experiments performed with respect to the voice quality.