Introduction to WiMAX Technology - Research Paper Example

Introduction to WiMAX Technology One of the vital accomplishments of the 21st century was the invention of the computer and the subsequent creation of computer networks. These two entities have virtually transformed the world as far as information processing and communication is concerned. WiMAX specifications have gained significant success in the provision of Internet access and broadband services via wireless communication systems. WiMAX is a wireless transmission technology that can be used to two wireless network categories; that is the wide area network, abbreviated as (WAN) and a Metropolitan Area Network abbreviated as (MAN).A MAN is a data network that may extend for several kilometers and is usually used for large campuses or a city. The advantages of WiMAX over higher capacity fiber cable, is the fact that it is cheaper to set up, yet capable of working in places with poor communication systems. This paper sets out to analyze WiMAX, which is increasingly becoming the preferred wireless technology for Broadband Wireless Access Systems. The paper discusses various aspects of the technology, including its mode of transmission, mobility and security Introduction Arguably one of the most epic accomplishments of the 21st century was the invention of the computer and the subsequent creation of computer networks. These two entities have virtually transformed the world as far as information processing and communication is concerned. The interconnection capability of computer systems can arguably be described as the feature that makes them more versatile and invaluable to their users. This being the case, the network functionality of computing systems has been exploited by organizations and individuals alike as efficient local and global communications became the defining attribute of success. As such, the creation of networks is key to any interconnected computing system. A network may be created that uses cables (fixed connection) or that use radio waves (wireless network). While fixed Internet networks continue to form the backbone of the communication system, wireless data transmission has become more favored for various reasons. Different forms of wireless technologies have come up to fulfill this role. Nuaymi (2007) asserts that WiMAX technology is at the present one of the most promising global telecommunication systems (p. 2). WiMAX emerged as a Broadband Wireless Access System that has many applications ranging from the mobile cellular network to backhauling. Considering the prominence of WiMAX in networking, this paper will set out to give a detailed discussion on some of the particular aspects of WiMAX. WiMAX Overview WiMAX specifications have gained significant success in the provision of Internet access and broadband services via wireless communication systems (Nuaymi, 2007). WiMAX is defined as a technology that provides for mobile and stationary broadband wireless access to "IP-based services through a standard radio technology, providing support for quality of service, roaming of mobile users and strong security" (Roh & Yanover, 2009). Khosroshahy & Nguyen’s (2006) established that WiMAX is considered as the "Last Mile solution which provides fast local connection to the network" (p. 3). An obvious merit of WiMAX over high-capacity cable/fiber is that it is less expensive to deploy and can be deployed in areas that lack a good telecommunication infrastructure (Brain & Grabianowski, 2015). WiMAX is distinct from Wi-Fi as shown by the following diagram. Figure1: Showing the differences between Wi-Fi and WiMAX Source: Haider, H. T. (2010). Wireless Communication using WiMAX technology. Journal of Engineering and Development WiMAX is a wireless transmission technology that can be used to two wireless network categories. These are the Wide Area Network abbreviated as (WAN) and a Metropolitan Area Network simply abbreviated as (MAN). MAN is a data network that may extend for several kilometers and is usually used for large campuses or a city. A WAN is a data network that spans a boar area and links various MANs. Scarfone, Tibbs, & Sexton (2010) reveal that WiMAX is the most commonly used form of WMAN and its promotion of interoperability between products based on the IEEE 802.16 standard makes it the model technology for this network (p. 2). Interoperability is ensured by the WiMAX Forum, which is an "industry-led non-profit organization" boasting of a membership of over 500 as of the year 2008 (Roh & Yanover, 2009). Dowd (2008) asserts that WiMAX, in essence, provides a feasible and cheaper alternative to wired WAN technologies such as cable or leased lines (p. 3). The architectural components of a WiMAX include; a Base Station (BS), Subscriber Station (SS), Mobile Subscriber (MS) and a Relay Station (RS). The BS connects and governs access to the devices from the wireless network subscriber to the operator network. The BS is made up of physical devices such as antennas and transceivers, which are necessary for the wireless data network communication. An SS is a fixed wireless node that communicates with the BS or forms a link between networks. AN MS is a wireless node that receives or transmits data through the Base Station. An RS is a Subscriber Station whose purpose is to retransmit traffic to the relay stations or subscriber stations. The figure below shows the variant WiMAX system that can be used to replace a telephone company’s copper wire network (Haider, 2010). Figure 2 WiMAX network in a variant way Source: Haider, H. T. (2010). Wireless Communication using WiMAX technology. Journal of Engineering and Development Key Medium Access Control (MAC) Features Mobile WiMAX has certain key MAC features that provide for higher efficiency and flexibility for which the technology is renowned (SimbaNET COM Ltd, 2011). To begin with the WiMAX provides for connection-oriented services with certain classification rules being specified so as to define the traffic that is associated with a particular connection. In each connection, qualities of service parameters are defined such as "minimum reserved rate and maximum sustained rate (Roh & Yanover, 2009, p. 8). The WiMAX technology also has mechanisms set in place to reduce the MAC overheads during transmission. In particular, the technology has support for General Purpose Header Suppression (PHS) as well as IP Header Compression (ROHC). Roh & Yanover’s (2009) study reveal that these mechanisms are useful since data a packet being transmitted at the network level contain many repeated parts of the header and by replacing this with short context identifiers, PHS significantly reduces the overhead that results from headers (p. 8). Another feature at the MAC layer that enhances the quality of service in WiMAX is the scheduling system specified by the IEEE 802.16 MAC. According to this scheduling, the subscriber station, which wishes to attach itself to a network, has to compete with others when it initially joins the network. A time allocation is made by the Base Station though this time slice can be expanded or reduced based on the needs of the SS. This slice remains assigned to the SS therefore ensuring stability under overload and oversubscription. The scheduling also has more bandwidth efficiency, which results in the quality of service since the resources are well balanced among the needs of the various SSs. Data Transmission WiMAX offers quite a number of coverage for its broadband wireless transmissions. SR Telecom notes that while most other technologies are limited to only providing lines of sight (LOS) coverage, WiMAX technology provides for optimal non-line of sight (NLOS) coverage as well (Nuaymi, 2007). When the WiMAX propagates signals between nodes at a frequency of 10-66 GHz, the signals are highly sensitive to radio frequency (RF) obstacles and as such, an unobstructed view between the nodes is required (Kalaichelvan, 2007). This is known as the line of sight (LOS) link where a signal has to "travel in an unobstructed path from the transmitter to the receiver" (Haider, 2010). If there is an obstruction in the line of sight between the transmitter and receiver, there will be a significant loss of signal strength resulting in poor performance. LOS employs relatively simpler RF modulation techniques as compared to NLOS. The power needed for transmission is also lower since the signal is propagated in a straight path (Zheng, Peterson, Davie, & Farrel, 2009) Figure 3: LOS Signal Transmission Source: SR Telecom. WiMAX Technology LOS and NLOS Environments. SR Telecom Inc, 2004. Non-line-of-sight (NLOS) coverage employs "advanced RF modulation techniques to compensate for RF signal changes caused by obstacles that would prevent LOS communication" (Scarfone, Tibbs, & Sexton, 2010, p. 3). The operation frequency is 2-11GHz depending on whether the link is being used for Mobile or fixed WiMAX operations. The NLOS signals on being transmitted reach the receiver through a combination of reflection, scattering, and diffractions. NLOS signals have been employed more often since the feasibility of LOS is hindered in many areas due to deployment costs, environmental and licensing factors. WiMAX that employs NLOS technology offers certain distinct advantages as compared to an LOS technology implementation. An NLOS system does not require antennas to be placed at the great heights that LOS systems call for. Also, NLOS technology results in reduced costs since extensive pre-installation site surveys are not necessitated before the system is installed. NLOS also enables the WiMAX technology to deliver services to a wider range of customers. Figure 4: NLOS Propagation Source: SR Telecom. WiMAX Technology LOS and NLOS Environments. SR Telecom Inc, 2004. Two techniques used to deliver broadband data at the physical layer are the orthogonal frequency-division multiplexing and orthogonal frequency division multiple access. Khosroshahy & Nguyen (2006) document that these techniques that have only been developed in the past few years "deliver broadband services that can be compared to those of wired services in terms of data rates" (p. 6). In OFDM technique, a single transmitter sends out a signal at different orthogonal frequencies using advanced modulation techniques to ensure that the signal has high resistance to interference. This method is favored by most operators since it has a superior NLOS performance due to its high spectral efficiency (Khosroshahy & Nguyen, 2006). OFDMA has the same operational principle as OFDM with the added advantage that it allows for multiple users to transmit data using the same spectrum simultaneously. This is achieved through the sharing of subchannels among the multiple users. Mobility WiMAX gives full mobility support for devices that may be moving below certain threshold speeds. Nuaymi (2007) goes on to illustrate that WiMAX also allows for portability since a user can move at a reasonable over a large area that is covered by multiple BSs without interruption of the current session or communication. The speed at which a mobile WiMAX device can move between cells in a seamless session is valued at 120km/h. Roh & Yanover (2009) state that WiMAX systems can "detect the mobile speed and automatically switch between different types of resource blocks to optimally support the mobile user" (p. 7). Besides, WiMAX technology employs Hybrid Automatic Repeat Request, which assists in the mitigation of the effect of the fast channel and interference fluctuation. Security Securing a network is at the best a very challenging task because new software and hardware keep being developed by the wireless industry and threats and vulnerabilities keep changing. As such, the security implementations of the previous year might prove to be grossly inadequate for the current year. With these considerations, the WiMAX technology has an intricate security architecture that is meant to ensure that the network is secure both for Fixed and mobile wireless access. Schmidt and Lian assert that the overall goal of the security architecture employed by WiMAX is to create an interoperable security solution that is stable but also accepts the common security protocols (p. 263). At the very basic level, all WiMAX links are encrypted, and for one to read the information, they need to employ some decryption mechanism. Extensible Authentication Protocol (EAP) which is based on mutual authentication between the mobile and the network is used at the security level of the WiMAX to ensure security. For fixed wireless access, WiMAX uses a "single network access authentication and authorization key established protocol Privacy Key Management" (Schmidt and Lian, n.d., p. 255). Mobile WiMAX networks require secure access, and authentication is mandatory before communication can commence (Schmidt and Lian, n.d., p. 258). WiMAX employs authentication and authorization processes for communication between nodes (Zhang & Chen, 2007). Authorization is the process of determining the level of access that a node is given after it has been identified and authenticated. WiMAX uses the public-key infrastructure for device authentication purposes. To provide secure communication, the WiMAX system performs the 3 steps of; authentication, key establishment and data encryption (Scarfone, Tibbs, & Sexton, 2010). Figure 5: WiMAX Security Framework Source: Scarfone, Karen., Tibbs, Cyrus and Sexton, Matthew. Guide to Security for WiMAX Technologies. National Institute of Standards and Technology It is worthy to note that WiMAX network specifications are constantly evolving and as such, the security architecture is expanding as well. Roh & Yanover’s (2009) study found that the Basic security mechanisms are strengthened by adding digital certificate-based Subscriber Station device authentication to the key management protocol (p. 9). Conclusion This paper sets out to analyze WiMAX, which is increasingly becoming the preferred wireless technology for Broadband Wireless Access Systems. The article discussed various aspects of the technology, including its mode of transmission, mobility and security. From the discussions undertaken, it can be seen that WiMAX technology is secure as a result or the authentication and encryption capabilities employed. A major strength of WiMAX has been seen to be its promotion of interoperability of broadband wireless products, therefore allowing products from various manufacturers to operate seamlessly on a network as well as its employing of NLOS technology which allows RF signals to be transmitted regardless of obstacles. From this paper, it can be suggested that WiMAX technology is the future of wireless communication over WMANS since it provides quality broadband services. As it currently stands, WiMAX specifications have gained significant success all over the world. It can, therefore, be projected that WiMAX technology will continue to be used as the technology of choice for wireless networks. References SimbaNET COM Ltd. (2011). WiMAX Wireless Broadband. Retrieved May 6, 2015, from SimbaNet Kenya: http://www.simbanet.co.ke/WiMAX.html Brain, M., & Grabianowski, E. (2015). How WiMAX works. Retrieved May 6, 2015, from How Stuff works: http://computer.howstuffworks.com/wimax.htm Dowd, K. (2008). Wireless WAN/LAN solutions for schools using WiMax, WiFi and Secured Access and Content. Virginia: Halestar, Inc. Haider, H. T. (2010). Wireless Communication using WiMAX technology. Journal of Engineering and Development, 142-159. Kalaichelvan, K. (2007). Wimax Explained; System Fundamentals. London: Eion Reference Series. KHOSROSHAHY, M., & NGUYEN, V. (2006). A Study of WiMax QoS Mechanisms. Paris: Telecom Paris. Nuaymi, P. L. (2007). WiMAX: Technology for Broadband Wireless Access. New York: John Wiley & Sons. Roh, W., & Yanover, V. (2009). Introduction to WiMAX Technology, in WiMAX Evolution: Emerging Technologies and Applications. Chichester: John Wiley & Sons, Ltd. Scarfone, K., Tibbs, C., & Sexton, M. (2010). Guide to Securing WiMAX Wireless Communications. Gaithersburg: National Institute of Standards and Technology. Zhang, Y., & Chen, H.-H. (2007). Mobile WiMAX: Toward Broadband Wireless Metropolitan Area Networks. Florida: CRC Press. Zheng, P., Peterson, L. L., Davie, B. S., & Farrel, A. (2009). Wireless Networking Complete. Burlington: Morgan Kaufmann. Read More