Personal Broadband Mobile
Networks
WiMAX / Wi-Fi / 4G PCS
Network Planners,
System Architects, Installers
Third Party, Independent Advisors and Consultants
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Network Planners,
System Architects, Installers
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Is WiMAX in your future? By Shiva Kavi
Where WiFi enables affordable broadband Internet access within short-range “hot spots,” at distances measured in hundreds of feet, WiMAX is designed to deliver the same access, at similar costs, but across several miles – and ultimately, with greater performance and higher speeds. In short, where WiFi provides high bandwidth but not distance, and current cellular systems provide distance but not high bandwidth, WiMAX is intended to provide both.
WiMAX is of interest to all kinds of operators – fixed and mobile, incumbent and alternative. By deploying a WiMAX access network, fixed operators will not only be able to offer wireless access, but also to offer nomadic and portable Internet services to complement their DSL and WiFi bundles. Mobile operators can integrate WiMAX into their networks to boost their portfolios by adding high bandwidth services to complement their existing data services. Access to the same applications (messaging, agenda, portal, etc) over different radio accesses can be offered with a single bill and a single subscriber profile.
Each operator may have different bandwidths available within the spectrum. The standard supports the flexibility of supporting multiple integer channel bandwidths of 1.25 MHz, 1.5 MHz and 1.75 MHz with a maximum channel bandwidth of 20 MHz. Different vendors are supporting different bandwidth options ranging from 3.5, 5, 7 and 10 MHz, to 4.375, 5, 8.75, 10, 17.5 and 20 MHz.
The WiMax standard supports multiple modulation and coding rates that can be used to achieve tradeoff between data rate and robustness depending upon channel and interference conditions. The modulation schemes supported are binary phase shift keying (BPSK), quaternary PSK (QPSK) 16-quadrature amplitude modulation (QAM) and 64-QAM. This provides the flexibility of supporting data throughput in the range of 2 Mbps to 18 Mbps with 5 MHz of spectrum.
In order to support flexible and inexpensive consumer deployment, non-line of sight operation is required between the base station (Tower) and Customer Premises Equipment (CPE). The reason for this is that the signal from the Tower may not be received directly from the Tower but may have to go around a building or tree before getting to the CPE. WiMAX provides this capability by using signals which are known Orthogonal Frequency Division Multiplex (OFDM) in which the original signal is split up into several tones and the information is disturbed across the tones. If some tones are lost the original signal can still be recovered.
Trials of WiMAX are currently taking place with the Fixed Version of WiMAX which was ratified in 2004. The standard for Mobile Version of WiMAX was ratified in October 2005 and trails should be taking place in early 2006. Commercial availability should be in the later part of 2006. For more information, email me: SK@PBMnetworks.com |
WiMAX,
is a new standard for the technology that can deliver wireless broadband
services. Its aim is to combine the speed of a broadband connection but with the
lower cost and convenience of not having wired infrastructure that's needed for
DSL connections or cable modems. WiMAX is an acronym which stands for World
Interoperability for Microwave Access.
Aimed
at metropolitan area networks (MANs), WiMAX is an emerging wireless broadband
access technology that can deliver broadband multimedia data over wireless links
at several times the speed of traditional wireless systems, and over a far
greater coverage area than today’s wireless local area network (WLAN) access
solutions, such as 802.11 (WiFi) technology.
