EE Times - Antenna diversity doubles CDMA net capacity -
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Published on: 5/12/2003
Last Visited: 11/4/2009
"Capacity, coverage and battery life are the operators' chief concerns right now," said Haim Harel, president and chief executive officer of Magnolia (Clinton, N.J.).
Operators have been interested in antenna diversity for some time, but "it has generally required costly network infrastructure upgrades or protocol changes and has only been performed on the downlink," Harel said.
Handsets with antenna diversity announced by Qualcomm and Nokia over the past 18 months, for example, have been limited to downlink implementations, Harel said.
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Harel said Magnolia's DiversityPlus technology requires no infrastructure or protocol upgrades and operates on both the uplink and downlink to achieve an improvement of between 4 and 5 dB in the signal-to-noise ratio (SNR).
"It also reduces PA [power amplifier] power consumption by up to 20 percent to get a 30-minute increase in talk time," Harel said.
"Because CDMA is interference-limited, every decibel increase in signal strength is an improvement in capacity," said Harel; hence the targeting of CDMA rather than GSM handsets, despite the larger potential market for GSM.
"With a 3-dB improvement," Harel said, "you can double network capacity."
For downlink diversity, Magnolia's implementation is not much different from current implementations in that it leverages the well-known signal-quality indicator that's part of the CDMA standard.
It uses that per-symbol update to perform equal-gain combining to achieve the downlink diversity.
But differences are apparent in the uplink diversity portion of the implementation, around which most of Magnolia's intellectual property and six pending patents revolve.
"While the downlink has the quality indicator, not many have noticed that the uplink has similar capability," said Harel.
"We change nothing; it's all there."
Magnolia's hook is the power control bit that follows channel fading and tells a handset either to increase or decrease output power depending on the channel impairments.
"While a small change takes you out of the null, this is a brute-force technique," said Harel.
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"We don't add chips; we just replace already established chips," said Harel, referring to the LNA and PA. "Also, while the algorithms run on an ARM [processor], they're processor-independent.
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