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TopIntroduction
World Interoperability for Microwave Access (WiMAX) is an emerging and exciting wireless technology that can support a variety of business and consumer applications, from network backhauling and interconnecting with wireless fidelity (Wi-Fi) and local area networks (LANs), to voice, audio, data and mobility support (Prasad & Velez, 2010). Mobile WiMAX may change the way people access data, e-mail, audio and video communication services as it provides a faster transmission speed than 3G, broader coverage than Wi-Fi and higher mobility than LAN. The performance of 802.16 WiMAX has been reviewed and reported by numerous researchers (Deruyck et al., 2010). However, most researchers have focused on WiMAX performance studies based on QoS or handoff. Therefore, diverse traffic types or node speeds are not seriously considered in their studies. However, users do not normally use a single application and do not move at the same speed all day long. Experimental results may change depending on which type of applications is used and how fast nodes move as applications characteristics differ and user speed is undefined and random. This paper addresses the following research question:
What impact do different traffic types (e.g. FTP, HTTP, voice, and video), and node mobility have on a typical 802.16 for varying network sizes?
To answer the question posed it is required to examine the impact of four diverse traffics, namely FTP, HTTP, VoIP and Video conferencing on the performance of a typical 802.16 WiMAX under light, medium and large network sizes. These traffic types were selected based on their popularity and practical applications.
The remainder of this paper is organized as follows. The following section provides a brief introduction to IEEE 802.16 standards and reviews relevant literature on performance evaluation of mobile WiMAX. Afterwards, the paper discusses the research methodologies employed. The network modeling and experimental scenarios are discussed next and following that the results are presented. The last two sections discuss the research findings and practical implications, and finally the conclusions of the paper.
TopBackground And Literature Review
The aim of the IEEE 802.16 group was primarily to address wireless technology applications to link commercial and residential buildings to high-rate core networks and thereby provide access to those networks. This link was called the “last mile”. The initial standard IEEE 802.16 has adapted many concepts from the cable modem Data Over Cable Service Interface Specification (DOCSIS) standard related to the Media Access Control (MAC) layer (Prasad & Velez, 2010) and thereby the 802.16 has evolved through several conceptual updates to standards such as 802.16a, 802.16b, 802.16c, 802.16d (Fixed WiMAX) and 802.16e (Mobile WiMAX). The first update (802.16 to 802.16a) added a wide range of spectrum (2GHz to 11GHz) with NLOS. Each subsequent update added a new functionality to and enhancements of existing features, such as scheduling of quality of Service (QoS) and FEC (Forward Error Correction) in the MAC layer.
IEEE 802.16d was the first practical standard of the IEEE 802.16 standards group and it is often called Fixed WiMAX. The IEEE 802.16d standard was released in October 2004 and replaced all previous versions of the IEEE 802.16 standards (IEEE_Std_802.16-2004, 2004). The IEEE Group completed and approved the IEEE 802.16e in December 2005, as an amendment to the IEEE 802.16d standard. IEEE 802.16e is often referred to as “Mobile WiMAX”. Mobile WiMAX creates a new market for mobile broadband services (IEEE_Std_802.16e-2005, 2006). To enable users to move from one cell site area to another the introduction of seamless handoff and a roaming scheme would be needed.
The IEEE 802.16e is an interesting technology that delivers carrier classes, high speed and wireless broadband at a much lower cost than cellular and provides much greater coverage than Wi-Fi (Shepard, 2006). Mobile WiMAX does not provide significant improvement in speed, throughput or capacity. However, it provides stable mobile services to portable end user devices, such as laptops and smart phones.