One up and coming Internet access technology is wireless. There are enough limitations in wireless connections so that they are typically the high-speed link of last resort.

There are two types of wireless connection, land-based and satellite-based. In both methods, you aim a dish-style antenna at the source of the signal.

On land, that antenna is attached to either a tall building or a tower of some sort. In Chicago, Sprint Broadband Direct (www.sprint.com) uses the Sears Tower and promises to add other, alternate antennas in the future. For satellite connections, the antenna is a low-orbit geosynchronous satellite hanging over a fixed spot on the equator.

In either case, the key principle is line-of-site. Assuming you are allowed to put up a dish (not an unimportant consideration), your dish has to have an unobstructed direct view of the antenna. If any buildings, trees, or even the curve of the earth's surface get in the way, you don't get a signal. Obviously, planning must include making sure that nobody is going to build or plant anything that will block your signal in the future. Flocks of birds, bad weather, and even sunspots can seriously disrupt the signal. In addition, there is a latency issue. That means that there is a lag time, sometimes quite a large one, in getting your signal. This can really screw up games, VPNs (Virtual Private Networks), streaming audio and video, and other timing-related software.

Historically, wireless connections have been one-way, where the return signal was carried via a regular phone line. The recent availability of two-way wireless will probably put an end to those companies still offering only one-way service. However, two-way wireless is typically very asynchronous, with the upstream channel sometimes barely exceeding regular modem speeds.

To put a bit more of a crimp in your enthusiasm, even the faster downstream rates are not guaranteed. You may find that the only time you get anywhere near the rated speed is around 3:00AM or so. Peak period speeds may be nowhere near the advertised speed, with a possible mitigating factor being that they define early evening, not regular business hours, as the peak use period. As your service provider becomes more successful and gets more customers, you will find out the disadvantages of shared bandwidth, where more is definitely not merrier. Having more customers means you get a slower effective speed.

Also, everybody gets every downstream signal, but only the correct receiver unit will do something with it. At least that's the idea. Of course, that's how cell phones are supposed to work, too, and you may have noticed that people are actively selling recordings of intercepted analog cell phone conversations. If you are passing sensitive data, you might want to check and see just how much built-in encoding your provider uses. If it's not sufficient, you may want to add your own encryption to any communications with another site that you control, or at least to your e-mail software. You don't want to find the secret planning report you sent to your main office published on the Web!

An additional limitation is the proprietary nature of many wireless links. StarBand (www.starband.com) satellite links, for instance, must terminate in a PC, without an intervening router or firewall, and must have proprietary compression/decompression running on that PC. This makes using common add-ons like firewalls, VPNs and even remote control software difficult, if not impossible. Now you know why I consider wireless connections the links of last resort.

Now, on to digital broadband cable. Yes, that's the same wire that brings you everything from the Soprano's to Sesame Street, with varying degrees of success. The first thing to remember before choosing cable is that every time your cable TV goes out, that represents a data outage you would have experienced. Also, every time your digital cable TV starts pixellating, where the picture regenerates so slowly that you see the individual dots slowly painting on the screen, that represents an extreme data slowdown - to a snail's pace - that you would have experienced. Sorry to be pessimistic, but you have to remember that cable TV consistently rates at the bottom of the scale for level of service.

The good news about cable is its potential for very high speeds, in the neighborhood of several millions of bits per second. At that speed, even having a slower upstream speed isn't that much of a disadvantage. However, at the moment, most cable systems are only offering asynchronous speeds in the range of 1.5mbps/384kbps or 768kbps/128kbps (downstream/upstream). To further annoy their customers, virtually all cable contracts allow providers to alter the rules at any time without notice. Several have arbitrarily cut some types of upstream traffic back to only 64kbps from 384kbps, giving a nasty surprise to existing customers.

While the cable industry has been quite hostile toward business use of their services, even to the point of discouraging telecommuters and home/office users, there is some indication that this may simply be a way to sell a separate business-level service by making the consumer-level service so incredibly unappetizing for business users. Some cable providers are starting this type of service, though not yet in the Chicago area.

Next month I will continue covering digital cable and move on to the most common choice of business users, DSL (Digital Subscriber Line). Now, as I watch Shark Week on the Discovery Channel, I am reminded of what an Australian shark expert once told me about how to avoid becoming lunch for a great white shark. He told me to figure out how to do the best impression of a seal that you possibly can - and then do the exact opposite.