Performance analysis of VoIP services over WiFi-based systems

In this paper we present a performance analysis about the capabilities of Alix board for handling VoIP over WiFi based systems with an embedded Asterisk server. First, we study the characteristics of all components of the Alix board to determine the possible options for operating systems that can run within this board using an Asterisk server. In addition we analyse the performance of SIP and IAX protocols combined with GSM, G.711 U/A, Speex, and G.726 codecs in WiFi based systems in conformance with IEEE 802.11b and IEEE 802.11g standards. Results were obtained using a SIPP´s tool which determines the boundaries reached by the board respect SIP protocol. Performance analysis was tested on metrics related to CPU percentage of use and RAM memory consumption depending on which protocols and codecs were used. The main results show the feasibility of implementing VoIP over small processors with low consumption of RAM memory. Finally, regarding CPU use percentage the best performance in a real environment was achieved when we used IEEE 8011.b standard, with IAX protocol and GSM codec, reaching up to 110 simultaneous phone calls with 29% CPU resources and 9,4% Memory to process simultaneous calls were achieved considering that phone calls have coexisted with other type of internet services.