LTE: Up for a test

"From a core technology perspective, WiMAX and LTE are actually quite similar," said David A. Hall, RF and communications product marketing manager at National Instruments (NI). "Core WiMAX technologies such as OFDM [orthogonal frequency division multiplexing] signal types and MIMO [multiple-input/multiple-output] signal processing algorithms are also used in LTE."

But the commonalities among the two broadband services' modulation and transmission schemes have not led to a concerted effort by test equipment companies and test engineers to develop common design, development and test platforms for the standards. For example, a software-defined platform on which WiMAX and LTE chips could be developed simultaneously, with optimization for one standard or the other occurring during the last chip design steps, would save on development and testing costs in an era of limited resources. Attempts to forge such a platform are under way, though they have yet to yield concrete results.

In theory, chip designers could make extensive reuse of gates to support both schemes in the same chip or chip set. And the WiMAX-LTE multimode challenge is a perfect opportunity for software-defined radio.

"WiMAX and LTE are both IP [Internet Protocol]-based technologies, so much of the implementations of both systems can be reused," said Siavash Alamouti, Intel Fellow and Mobility Group CTO. "OFDMA [orthogonal frequency-division multiple access] plus MIMO are key enablers of mobile broadband Internet, and both technologies have a fair amount of testing for interoperability among devices and conformance to each standard."

Intel is heavily involved in developing WiMAX chips and has brought its weight to bear on WiMax development and testing schemes. But Alamouti said the company "has zero activity in LTE," preferring to wait for LTE standards to "work themselves out first."

At the physical layer, both standards use key technologies such as OFDMA and MIMO, noted NI's Hall; thus, both standards will have similarities that are common to all OFDM signals.

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