Asia's love of mobile phones is fuelling a boom in the adoption of personal navigation devices, recent data reveals.

Shipments of personal navigation gadgets and GPS-equipped handsets will increase fivefold over the next five years, according to ABI Research.

ABI analyst Wang Tao said that almost 40 million devices of various kinds were sold in the region last year, and more than 185 million will ship by 2012.

The market will achieve growth rates of almost 40 per cent per year in South Korea and 137 per cent in China.

In Asia's less developed nations, road signs are relatively sparse and even occasionally misleading particularly on smaller roads.

Weak law enforcement in remote areas means that aluminium signs and their supporting poles are often stolen and sold for scrap.

In the region's crowded cities, meanwhile, uncontrolled placement of brightly-coloured advertising and commercial signage obscures official road signs, or at least makes them difficult to pick out.

"Buyers in regional Asian markets show distinct preferences in the kinds of devices they adopt," said Wang.

"But our research suggests that device connectivity and the integration of several functions will provide the best penetration as these markets evolve in the next five years.

"Navigation devices are not just navigation devices anymore, and the introduction of new technologies will help lower-priced competitors to differentiate themselves."