Wireless Systems Design

Presentation Spotlights WiMAX

One of the highlights of last month's Wireless Systems Design Conference & Expo (www.wsdexpo.com) was a presentation by Aditya Agrawal, Senior Marketing Manager, Fujitsu Microelectronics America. With his timely focus on WiMAX, Agrawal garnered a lot of attendee interest. His presentation was titled, "The Benefits of WiMAX Implementations for a New Generation of Broadband Wireless Access." In it, he explained the broadband-wireless marketplace, the standards that are currently in use, and the need for WiMAX.

His presentation was broken down into the following categories: IEEE 802.16, WiMAX, spectrum, WiMAX certification, and implementation issues. The Worldwide Interoperability for Microwave Access, or WiMAX, has been established to promote a global standard for the deployment of broadband-wireless-access networks. Importantly, it also was developed to certify that products interoperate. A WiMAX option exists in the form of the IEEE 802.16a standard, which was designed for the outdoor MAN. That standard focuses on defining high-level features and interfaces. It leaves the specific implementation details of the system-on-a-chip (SoC) to individual developers. Currently, there is a requirement to extend and expand IEEE 802.16a by defining specific enhancements and establishing standards-based interoperability among products from different vendors. A WiMAX-based system will deliver the key requirements that would need to be met by such a broadband wireless system.

To show the market niche for WiMAX, Agrawal contrasted this standard against the 802.11 standards. According to his presentation, the 802.16 physical layer (PHY) tolerates 10 more multipath delay spreads than 802.11. In addition, 802.16 boasts 256 OFDM versus the 64 OFDM of 802.11. It also offers adaptive modulation.

Also, note that 802.16 is only limited by available spectrum. It is in stark contrast to the three non-overlapping 802.11b channels as well as the five channels for 802.11a. 802.16 sets itself apart even more with its grant-request MAC. The 802.11 standards have a contention-based MAC.

After clarifying those differences, Agrawal went on to explain the 802.16 standard and usage-model mapping. He provided images of the typical uplink subframe (TDD or FDD) as well as the TDD and FDD downlink subframes. He then explained the changes that are needed for the standard to evolve, such as a special interest group for the upper-layer network infrastructure.

The economic and technical benefits of WiMAX are already becoming clear. The standard also is evolving according to a somewhat predictable timeline. Test labs are staying on top of conformance, while PlugFests are busying themselves with interoperability. This standard is paving its way toward the future. For wireless users around the world, that future could be filled with real broadband access.

Copies of Aditya Agrawal's presentation can be downloaded from www.fma.fujitsu.com/reg_wsdc04.asp.

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