The Walls Have Ears in 3G UMTS Land

1st July , 2004

US : What happens to the "last mile" segment of mobile telephony networks when that last mile happens to fall inside a big building? That depends on the technology involved. Most of us have experienced lack of signal inside large buildings even with 2G mobile phones. With the much higher 2.1 GHz frequencies used in the Universal Mobile Telecommunications System (UMTS) services so far deployed (all outside North America), the penetrating power of the signal through the so-called "first wall" is sharply reduced.

So users of the 23 existing UMTS services around the world could face the loss of the advanced functions they're paying for, when they're at work in an office block, or shopping at the mall.

The solution? UMTS antennas distributed within large, hard to penetrate structures. According to Ray Jodoin, Director of Wireless Infrastructure Research at ABI Research, such an architecture eliminates the usual cell area 'shrinkage' in high traffic conditions. "A smaller building", he says, "will get better penetration between floors than a bigger building. So for a shopping center two or three floors high, you'd cover every nook and cranny." European shopping centers are among the first to deploy such "micro base stations", but the implications for wireless markets vary between countries: France, for instance, lacks large retail complexes, while neighboring Belgium has many.

In North America, the situation is different. First, no UMTS services yet exist there. (Limited, early trials are scheduled to begin this summer.) But even when they do arrive, they will operate first in the 1900 MHz band and later, perhaps, in the 850 MHz band which has better penetration of physical obstacles.

ABI Research has published a report, "In-Building Wireless Systems", which studies all aspects of mobile communications within structures. It includes Wi-Fi as well as cellular communications, and analyzes the factors that will drive or inhibit this crucial but often-ignored link in our wireless networks.

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