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How much do you know about OFDM, WiMAX?

Posted: 09 Jan 2009 ?? ?Print Version ?Bookmark and Share

Keywords:OFDM? WiMAX? 3G technology? Long Term Evolution?

OFDM and WiMAX are hot topics on the RF DesignLine, so I had a virtual "sit down" with some industry leaders to get a peek at where the technology is, and where they think it is going.

The article includes some of the thoughts and remarks of How-Siang Yap, Agilent EE of EDA product marketing; David Hall, product manager, RF and communications National Instruments; Paul Argent, business manager WiMAX, Aeroflex Wireless; and Carla Feldman, marketing manager, wireless business unit Agilent Technologies.

After the interview, I've included some links to some of the most popular OFDM/WiMAX articles on the site.

RFDL: What is the status of the technology?
Yap
: OFDM is a mature modulation technology used in wireless and wired digital data transmission such as WLAN, WiMAX, ADSL, Powerline, digital TV and digital radio.

Argent: The establishment of industry-wide standards for WiMAX is enabling both service providers and technology vendors to make commitments to the technology. Operators all over the world are beginning to focus on the commercial opportunities presented by WiMAX technology. Component vendors, infrastructure vendors, and device manufacturers are each playing a role to advance the development and commercialization of WiMAX.

Hall: One continuing trend in the wireless communications industry is the emergence of MIMO-OFDM in the physical layers of new communication standards. In fact, the presence of MIMO-OFDM in the physical layer of protocols such as WiMAX, 3GPP LTE (Long Term Evolution) and IEEE 802.11n is the direct result of consumer demands for higher data rates without consuming more channel bandwidth. It is likely that MIMO-OFDM will continue as the fundamental backbone of future broadband communications technologies.

Feldman: There is no doubt that WiMAX (OFDMA) and 3GPP LTE will continue to have a significant and lasting impact on the communications industry in 2009. R&D spending in LTE, for example, has already begun ramping up from chipset development to components and integrated hardware. The same can be said of the technologies that go into making an LTE system work such as MIMO and DigRF V4-the latest version of the DigRF electronics interface standard for the cellular market.

How do you see market opportunities?
Hall
: Up until now, most WiMAX deployments have been of the IEEE 802.16d (fixed) variety as a method to deploy broadband Internet. The year 2009 will likely see continued deployment of fixed WiMAX for broadband Internet both in emerging economies that lack the communications infrastructure, and in urban environments. With most cellular handset manufacturers predicting flat unit growth in 2009, it seems likely that the growth of new WiMAX-enabled handsets will help to offset the inevitable decline in unit profit margins.

Argent: WiMAX is picking up momentum and is looking poised to become part of your personal gadgets like laptop computers, personal media players, PDA devices and eventually mobile phones. Indication of WiMAX growth is the development in the WiMAX semiconductor market and the announcement of Certified Base Station and Mobile Station devices from leading equipment vendors. Market researchers endorse that WiMAX is entering its seminal year with more than 200 infrastructure deployments underway and more advanced WiMAX capable mobile platforms expected from leading vendors in 2009.

Feldman: While WiMAX and LTE will continue to dominate the industry as "killer apps" in 2009, at Agilent we also see the emergence of femtocells and other technologies getting traction. As service providers work to establish the mobile device as the home's central communication device, deployment of femtocells will likely garner increasing attention for their ability to help increase home coverage and cell site capacity.

Yap: OFDM/WiMAX will continue to grow with the rise of internet usage to provide convenient wide area wireless broadband access without the need for cable or DSL wiring. However, for mobile applications, it faces competition from LTE which provides lower battery power consumption and less stringent power amplifier requirements which translates to more affordable broadband mobile handsets.

What do you wish every RF engineer knew about this topic?
Hall
: No matter who wins the WiMAX versus LTE race, all engineers in the wireless communications industry need to better understand the basic fundamentals of MIMO-OFDM systems. In addition, with increasing market pressure to reduce unit cost, test engineers need to gain more expertise in techniques to reduce measurement time.

Feldman: As RF engineers push the limits of these new technologies, measurement companies will also be driven to push the limits of test and measurement in support of their efforts. For instance, the 802.16 standard on which Mobile WiMAX is based, specifies a tight error vector magnitude requirement (-31dB, based on a 1 percent packet error rate). Meeting this target requires that all system blocks be more linear and phase noise be considerably better than in an 802.11 design.

Argent: RF optimization is always a challenge with a new technology, a design is never complete until it has been superseded by a more advanced feature set or optimized version. WiMAX has an abundance of optional features/techniques including advanced antenna solutions such as downlink 2x2 MIMO, uplink Interference Rejection Combining (IRC) reception, uplink collaborative MIMO and beam forming that can greatly improve performance. If every RF WiMAX engineer employed the precise mix of WiMAX optional features, advanced signaling processing and smart antenna techniques, WiMAX technology is capable of delivering world-leading wireless broadband performance.

- Janine Love
RF Designline





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