White Paper on Wi-Fi, TurboCell® and WiMAX

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Why WiMAX?

Wireless LANs, and the emerging wireless broadband wide area networks, based on IEEE 802.11a/b/g (otherwise known as Wi-Fi™) have become a phenomenal success. They are one of technology's few bright growth areas. The ability to use competitively priced, easy to install and FCC-license-free RF devices to connect computers and LANs the last 100 feet (and up to many miles) has emerged as the fastest growing technology of the last few years.

Wi-Fi, short for Wireless Fidelity, was coined as the layman’s marketing name for products based on the 802.11 set of standards. Wi-Fi is also a forum to promote interoperability between vendors and help get equipment to market faster. The key to the success of 802.11/Wi-Fi was taken from the pages of all product success stories: the right technology at the right time, with the right price, solving a clear customer need. For the sake of this paper we will call this market the “indoor Wi-Fi” market, which implies short distances (less than 100’) with full 360-degree radio coverage.

As the indoor Wi-Fi market has been maturing, the 802.11 and Wi-Fi standards group has not been idle. As with all standards, 802.11 is maturing quickly with many enhancements being proposed. This is due to a plethora of applications that are being developed by countless vendors based on basic 802.11 technology. A few examples of current standards work is summarized in the following table:

WiMAX and 802.16a address a segment of the wireless market that was not originally addressed by 802.11a/g equipment. It addresses the issues of hidden nodes, QoS (CIR and MIR, and maximum delay), and reduced RF bandwidth options. These issues were unique to outdoor wireless broadband distribution systems, but are now becoming issues for indoor Wi-Fi as higher bandwidths are being demanded and products with multimedia capability are being introduced.

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TurboCell®: A Precedent to WiMAX

Terabeam Wireless brings over a decade’s experience in the development of software to address issues that have surfaced as the marketplace seeks to use 802.11-compliant networks in new applications and environments. Our TurboCell™ is a software extension to 802.11 that adds the 802.16a features today. The TurboCell enhancement is what makes 802.11 work properly outdoor in the wireless ISP and wireless backbone applications. In a sense, 802.11 with TurboCell is a pre- 802.16a offering that has a significant installed base today. The following table compares equipment based on current 802.11, and 802.11 with TurboCell to the proposed WiMAX standard.

* 40 MHz bandwidth is not 802.11 standard but is an industry standard in currently shipping products. 5 and 10 MHz are built into the chips and will be shipping Q4’04.
** 256 QAM is highly sensitive to RF interference.

The following are current gaps from our perspective in the 802.16a standard that must be addressed:

• Authentication — 802.16a and WiMAX have none
• Range — Existing 802.11 networks work up to 30 miles
• Encryption — 3 DES is considered less secure than AES
• Mobility — 802.16a is just beginning to address these issues; 802.11 is mature
• Pricing — as of mid-year 2004, a WiMAX CPE unit was predicted to be priced at just under $500 by the end of 2005
• Delivery — the experience with the 802.11 products, where it took about four years from standardization to product volume shipments, creates a question about how feasible it will be to have WiMAX products shipping in volume before 2007.

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TurboCell^®: Enhancing 802.11 Network Performance Today

Currently shipping 802.11 equipment (non-802.11e) suffers performance problems in “outdoor” deployments. The addition of TurboCell software improves the outdoor performance of standard 802.11 radio equipment in the following ways:

• TurboCell improves radio performance where it is needed most. TurboCell implements a packet bundling function to dramatically improve radio efficiency. An example of this is that at the 54Mbps radio setting, data is really forwarded at 34Mbps for large packets or 3.4Mbps for small packets. TurboCell’s packet aggregation allows for the full 34 Mbps transfer rate at all packet sizes.
• TurboCell resolves the hidden node problem in point-to-multipoint installation. Although the 802.11e standard addresses these issues, that part of the standard is not yet implemented in the shipping product.
• TurboCell implements bandwidth management (MIR) – This important bandwidth management feature is not part of the 802.11 or 802.16a standard. TurboCell provides this feature.
• TurboCell also improves standard 802.11 on-air protocol to make it
  • Less subject to denial of service attacks
  • Less subject to phantom AP attacks
  • Implements built-in wireless link tests
  • The on air data rate does not fall-back as quickly as 802.11.

TurboCell is presently available in a number of Terabeam Wireless solution sets, including TeraMax™, the EtherAnt-Turbo client and as a software-only license.

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