Wireless Systems Design

Transmit And Receive Diversity Comes Alive

Smart-antenna processing, which also is referred to as antenna diversity, has been hailed as the data-throughput savior. In the past, this term solely connoted receive diversity. Now, a technology platform from Magnolia Broadband, Inc. (www.magnoliabroad-band.com) boasts both transmit and receive density for cellular phones. The company's radio chip promises to extend cell-phone battery life while improving coverage and doubling existing network capacity.

Called DiversityPlus, this technology platform uses dual antenna inputs and outputs. In doing so, it can create more robust signals through diversity algorithm processing. The DiversityPlus RF product family is based on both the company's proprietary algorithms for CDMA mobile terminals and its radio-frequency integrated-circuit (RFIC) designs (see figure).

The DiversityPlus technology uniquely combines the transmit and receive RF signals from two antennae. With the signals that are received from those antennae, the receive technology performs its quality-based combining process in the RF level instead of the baseband level. The architecture eliminates the need for a second receiver chain, thereby reducing cost and design issues.

In the mobile terminal, the Diver-sityPlus technology demands no changes in either the service provider's network or wireless standards. This is good news for carriers, as they are looking to roll out data services in hopes of increased revenue. DiversityPlus promises them a way to profitably provision data and voice services on current networks while they're preparing for 3G. By implementing this technology, a carrier is predicted to reap substantial savings compared to the costs of upgrading and maintaining an expensive network. Plus, the technology can be phased in as demand grows.

DiversityPlus also vows to tame the spectre of battery life—a problem that will only grow with the proliferation of new applications. The cell phones that are powered by this technology will supposedly boast 30 to 40 min. of extra talk time. They also will enable carriers to improve coverage and data throughput while serving twice as many subscribers with the same infrastructure.

Over the next six months, Magnolia will be conducting its second phase of field trials with wireless service providers. The company is working on delivering engineering prototypes of its DiversityPlus chip sets. It soon expects to announce supply agreements with mobile-terminal manufacturers to integrate the chip sets in commercial handsets. The first products should ship in sample quantities toward the end of this year.

This is the first technology to combine both transmit and receive diversity. Due to its use of multipath, such a technology could help carriers provide services indoors.

TAGS: Mobile
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