WiMax broadband wireless access Introduction Wireless communication is considered one of the big engineering success stories over the last two decades. It is one of the rapidly changing fields that demand for faster data rates with longer transmission ranges to meet the standards of new applications. One of the newest technologies in broadband wireless access is WiMax which enables highspeed fixed wireless communication. WiMax is expecting to quadruple the data rate of previous technology while increasing the coverage and it will compete with the Wi-Fi, 3G, and last-mile internet technologies such as DSL and cable. This paper focuses on the commercial applications of WiMax application, the technology behind the WiMax process, and how to implement the technology. Commercial application of WiMax The key aspect of broadband wireless access service that the customers demand are to provide personalized and uniform multimedia services that are available via any terminal, plus the service should be secure, reliable, and inexpensive. Presently WiMax portable devices that support mobile broadband applications are still small in number. The WiMax Forum is still certifying mobile WiMax products, and the large-scale commercialization of WiMax for mobile broadband access cannot be realized in the short run. [3] WiMax technology provides a stepping-stone to wireless access expansion. Content providers such as television, news, and new service developers, who provide telecom value-added services, are not satisfied with the traditional operators low data rate and small transmission ranges. Internet service providers with many Wi-Fi hotspots
are hoping to use WiMax to make up for the coverage insufficiency of Wi-Fi. Service modes for wireless broadband are mainly high-speed network access and VoIP. Price is the upmost concern and the WiMax service currently is somewhere between DSL and 3G. Clearwire for example, provides two types of bundling. One is the bundling of broadband access and voice services, which attracts mobile only households and SME subscribers. The other is the bundling of modems and PC cards, which help Clearwire, get more customers from cable and DSL operators. [3] Intel has announced plans to use mobile WiMax capabilities into next-generation centrino 2 laptop Wi-Fi chips in the near future and Nokia plans to incorporate this chip family in its next-generation tablet computer. [2] WiMax can provide ultimate mobile broadband services with limited mobility, especially for large-screen terminals. Underlying technology behind WiMax The physical and MAC layer of WiMax IEEE 802.16 added more complexity from the previous Wi-Fi IEEE 802.11 standard. WiMax is widely known for its high flexibility in frequency distribution (2.3GHz, 2.5GHz, and 5.8GHz), channel bandwidth (1.25-20MHz), and application scenarios (wireless bandwidth, mobile bandwidth, and transmission of BTSs and Wi-Fi). [3] Unlike the previous wireless technologies, WiMax allows data transport by using multiple broad frequency ranges and this technology will avoid using frequencies that might interfere with other wireless applications. [2] WiMax technology can transfer high data rates in part with OFDM (orthogonal frequency division multiplexing). OFDM increase bandwidth by splitting broad channels into multiple narrowband channels, each using a different frequency, which can then carry
different parts of a message simultaneously. [2] MIMO (multiple-input and multipleoutput), also known as SM (spatial multiplexing), is a powerful technique improvising multiple antennas to increases the data rate in proportion to the number of transmit antennas since each transmit antenna carries a unique stream of data symbols. This technique was first introduced in IEEE 802.11n standard version of Wi-Fi and later implemented to WiMax. [1] WiMax theoretically can provide maximum data rate and transmission range of 70 Mbits per seconds within 35 miles range. However, due to the fact that the rate attenuates over the long distance, modems support a sustained bandwidth of only 6 Mbits per second within a mile range. Compare to that of 3G (3Mbps within 3 miles) and Wi-Fi (54 Mbps within 328 feet), WiMax can provide more data rate and transmission range by significant amount. [2] Implementation of WiMax There are four crucial components that are needed to implement WiMAX: base station, WiMax hub, access point, and WiMax enabled devices. Base stations are spots which provide customer with wireless connectivity such as satellite which relay signal back and forth. WiMax hub is core base station from where everything is sent to base station. The functionality of WiMax hub is that of a server in which acts as a source of brain of the network. Access Point allows wireless communication devices to connect to a wireless network and it is mainly used when there is more than one wireless gadget requiring access to the WiMax network. WiMax enable devices include laptop, desktop, Wi-Fi hotspots and other devices. [4] The transport network of WiMax hub includes
internet technologies along with microwave links. The network includes a back-end infrastructure for centralized user authentication, authorization, and account (AAA) as well as billing solutions that can be based on time, volume or content. The end-to-end network plays a key role in broadband wireless access. Server using WiMax must provide advanced equipment including centralized AAA, IP configuration servers, and user profile database that support roaming agreements. [5]
[1] Ghosh, A., D. R. Wolter, et al. (2005). Broadband wireless access with WiMax/802.16: Current performance benchmarks and future potential. IEEE Communications Magazine 43(2): 129-136. [2] Vaughan-Nichols, S. J. (2008). Mobile WiMax: The next wirelsss battleground? Computer 4 1(6): 16-18 [3] Yang Hu and Yao Zheng, Wireless broadband commercial application accelerates, [Online], [cited 2008 Aug 28], Available HTTP: http://www.huawei.com/publications/view.do?id3082&cid=5463&pid=61 [4] Ashish Mohta, Future of Wi-Max and its implementation [Online], [cited 2008 Aug 28], Available HTTP: http://www.johntp.com/2007/04/11/future-of-wi-maxand-its-implementation/ [5] Siemens, How to implement WiMax in a mobile network, [Company Website], [cited 2008 Aug 28], Available: http://www.cisco.com/cdc_content_elements/flash/mobile_sols/partners_site/pdfs/ parters/siemens/wimax_implement_wp2.pdf [6] Molisch, A. F. (2005). Wireless communication. Chichester, England ; Hoboken, NJ, John Wiley & Sons.