Wireless Access Type

    WiMax is a metropolitan Area Network optimized for broadband data. The following figure demonstrates the different ranges of wireless technologies:

Wireless Access Comparison

• To help better understand where WiMax fits amongst other wireless technologies, we created the table below.  

• The "advertised" data rate of WiMax is 1.5-2 Mbps, though some preliminary tests are showing data rates of 500-700 Kbps on busy networks. One the important features of WiMax though is how it handles contention, which makes for much more stable networks under over-utilized network conditions.

WiMax Services

• Capable of providing the following services:

• Different services require different MAC sizes, and headers
• The  logic link control (LLC) is created by the convergence layer (see Protocol Architecture for details )
• The LLC "understands" the service required by the subscriber, and based on the type of service it chooses an appropriate MAC header
• LLC header ensures that MAC format is compatible with  subscribers required service
• The MAC layer is capable of accommodating all the above services
• The example below demonstrates a TCP/IP WiMax MAC frame

TCP/IP WiMax Example

• One of the services that WiMax PHY layer is capable of providing is TCP/IP. The following example demonstrates the WiMax frame structure.

   The IP datagram, which contains a TCP segment, is encapsulated in a PDU, protocol data unit. The PDU is encapsulated in a WiMax MAC frame and transmitted wirelessly. At the receivers end, the MAC header is removed first. Secondly, the LLC header is removed, and what's left is a plain old IP datagram.

   The LLC header acts like an adapter, that translates the type of service required by the WiMax subscriber into an appropriate MAC header capable of providing that service. Using different MAC headers, WiMax can meet the QoS requirements of ATM also.

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