Business adopts military technique

ALTHOUGH originally developed for military purposes, spread spectrum technology is finally reaching its true potential through widespread commercial use.

Today, its effect on second generation wireless local area networks (LANs) is such that wireless is rapidly approaching the performance levels of its wired cousins.

Spread spectrum has provided a strong impetus for the entire wireless LAN industry by helping to fill the demand for flexible and reliable networking.

Because they complement wire-based LANs, wireless radio LANs promise to expand the overall LAN marketplace, much as the introduction of unshielded twisted pair increased the overall number of LAN connections in the 1980s.

It is easy to see why.

With more than half of Asia's multinational companies located in Hongkong, large corporate headquarters often need networks which can deal with a high degree of mobility.

Also, with space at a premium in Hongkong, such enterprises are faced with the problem of what to do when existing cable troughs are filled to capacity.

As a result, network managers faced with logistical problems are finding wireless LANs to be a good solution to difficult problems - often providing a cheaper alternative to wired LANs.

Although first designed as a safe and secure medium for battlefield communications, spread spectrum differs from other transmission methods by spreading the data stream across a wider band of radio frequencies, or over the entire available bandwidth.

The most common technique used today is to take each data bit and break it down into multiple sub-bits of a fixed length called chips, with a ''1'' represented by a given pattern and a ''0'' by its inverse.

The chip patterns are what are actually transmitted. This has the effect of ''spreading'' the signal by a factor equal to the length of the chipping code.

This accelerates the movement of data, as well as providing for more secure and reliable data transmission.

In wired transmission, it is often assumed that data is more secure and more difficult to intercept than broadcast transmission. In fact, the opposite is true.

Cable is only as secure as the physical access to any point on the wire, while data can be easily intercepted by placing another wire near the one carrying the signal data.

Wireless LANs employing spread spectrum, on the other hand, achieve data security by modulating the radio broadcast signal in such a way as to encrypt its content.

Figures released by the International Data Corporation bear out optimistic projections of growth for wireless LANs during the next two years.

They project revenue derived from sales of wireless LANs to reach US$500 million by 1995.

Even more interesting are the projections of growth for the installed bases, predicted to grow from 68,000 nodes in 1992 to 306,000 in 1993.

IDC also predicts that, by 1994, more than 530,000 computers will be connected by wireless LANs.

Barry Bonnett is managing director of ITS Asia Pacific