Voice over Internet Protocol (VoIP) over a wireless local area network (WLAN) is already an important Internet application. The data rate required for each VoIP stream depends on the used codec and the TCP/IP protocol overhead that typically add 98 bytes in the codec payload. As the G.726 codec has 80-byte payload (32 kb/s), the overhead represents 55% of the total packet size (178 bytes). This...

As cellular networks are evolving into high data rate systems, cdma2000 1x EV-DO (HDR) has been highlighted and deployed for data-only wireless service. For wide applications, it is expected to serve some real-time traffic including VoIP. To meet the loss requirement and to ensure the delay bound of VoIP packets, we consider two scheduling algorithms that are channel-aware and flexible in the f...

In this paper, we study the inherent limitations of the 802.11 (a/b) distributed coordination function (DCF) in supporting VoIP calls over a wireless LAN. Specifically, we evaluate the upper bound on the number of simultaneous VoIP calls that can be placed in a single cell of an 802.11(a/b) network. Making one additional VoIP call in that cell would degrade the quality of all VoIP calls. The up...

Today, wireless LAN (IEEE802.11g/n) has been the dominant wireless network that can provide high data rates in a limited coverage area. While emerging mobile WiMAX (IEEE802.16e) can provide a wireless broadband access to mobile users in a wide coverage area. These two different technolgies will co-exist while complementing each other in some regions, hence, a mobile node (MN) with dual interfac...

In this chapter, we present a solution for evaluating the Quality of Services (QoS) of Voice over Internet Protocol (VoIP). First, we present an introduction to the main concepts and mathematical background relating to QoS and Internet Protocol (IP) traffic nature, which subsequently are used in the measurements, analysis, and modeling of VoIP traffic. Secondly, we analyze network measurements ...

VoIP is a rapidly growing area with great market potential. To promote it for both commercial and research purposes, we are developing an efficient voice access system based on state-of-art Motorola communication techniques. It is composed of a communication subsystems, a voice interface, and an information agent. Implementation of the high performance communication system is described in this ...

Voice-over-IP (VoIP) has rapidly gained popularity in the last years, especially on smartphones platforms. In fact, WLAN chip-sets are becoming more common on smartphones, allowing users to use VoIP services from their mobile devices. On the other hand, the excessive energy consumption of the WLAN chip-set, limits the widespread use of VoIP on mobile phones. As most of the energy is spent when ...