Wireless Networking with RadioLAN

by Ben Adida for Web Tools Review

Quick Summary: With one minor exception, RadioLan products are very impressive. They provide very good bandwidth in an easy-to-use package. The price is a tad high, but the amount of time saved and the great convenience of fast, worry-free, wireless networking is well worth it.

Whether it's because you're setting up a home office, small office, or just because you're walking around your living room with your portable computer, you've probably wondered whether you could wirelessly connect your computer to an Ethernet network. This is an especially interesting prospect for connecting computers that have a tendency to move around (laptops or just a regular desire to reorganize the office). Today, there are a number of solutions for doing just this. Some systems use high-frequency communication over existing wiring, like the telephone wire or the power wiring inside a building. This doesn't usually provide very interesting transfer rates, but it works well when one needs a cheap solution to connect a couple of computers for small file transfers, or for sharing a modem connection to the Internet.

When it comes to serious networking to share a full 10 Mbps connection (or close), the price of these systems skyrockets. RadioLAN (http://www.radiolan.com) is just such a system. It's expensive. But it's a very good product in almost every way.
 

The Difficulty of Wireless Networking

My first thought when I started considering wireless networking was that it should be as simple as connecting the ends of an Ethernet network to some wireless transmitters. Why the expensive equipment when the problem of sharing the same "ether" was already solved by Bob Metcalfe at Xerox Parc in the late 70s? You could say that it's a good thing I'm not a network engineer. It turns out that Ethernet (otherwise known as IEEE 802.3) relies on properties of wired networks to detect packet collisions and recover from asynchronized simultaneous transmissions (or so I'm told). Wireless networking has to do things differently. That's where 802.11 comes from. 802.11 is an IEEE standard for wireless Ethernet which currently allows approximately 2-3 Mbps of transfer speed. 802.11 does specify a protocol for transfering 11 Mbps, and certain companies like Lucent are already looking at making 11Mbps wireless transceivers. Most products on the market today only support 2Mbps, though.
 

RadioLAN Basics

On the other hand, you've got Radiolan. Radiolan uses standard 802.3 technology. I'm not sure how they handle the packet collision issues, but their claim is that they do Ethernet over wireless. That means the full 10 Mbps. What it also means is that Radiolan makes an Ethernet-to-wireless-ethernet converter, which means you don't necessarily need an ISA or PCMCIA card and special drivers that work with your operating system: you just need Ethernet support, which is relatively cheap, and certainly easy to get for any platform.

RadioLAN has four major products for localized wireless networks:

I tested all four of these products by plugging my wired network into a bridge, and then connecting a desktop Wintel, a portable Wintel, and my Apple Powerbook to their respective connectors onto the wireless ether. I maintained this network running over a period of a few months, testing range, speed of transfer, ease of use, and durability of the equipment
 

Installation

For each type of wireless connector, the installation was child's play. Instructions are extremely clear and simple. Installing the ISA card and the Windows driver was done in under 15 minutes (which is pretty impressive for a Windows installation). Installing the PCMCIA card and the Windows driver on the notebook was done in under 10 minutes. Plugging the Mac into the DockLink was as easy as plugging it into an Ethernet hub, and took 30 seconds. Installing the bridge from the wired to the wireless network took a few minutes, and the wireless pieces then proceeded to auto-configure themselves. In under a half hour, I had four computers talking over wireless. Hats off to Radiolan.

Range

The documentation claims that the range of these systems is 120 feet without obstruction. What I found is that the actual range is at least as good as that. Without attempting to find the best possible antenna position, I was able to connect from 100 feet away, through a metal door. Similarly, I was able to connect onto the wireless network through 2 brick walls, at about 50 feet of distance. The bandwidth rarely decreased during these tests: reception seems to be binary in that, at a sudden cut-off distance, the connection dies instantly. At any point until that cut-off, however, the bandwidth remains the same.

Bandwidth

The documentation claims that Radiolan products function at full 10Mbps. While I wasn't able to get full 10 Mbps transmission, I'm not blaming this on Radiolan: I wasn't exactly able to get 10 Mbps over the wired network either. It would have taken a few more computers to completely overload the 10Mbps connection . I was, however able test file transfers at over 800 Kilobytes per second, or 6.5 Mbps.

Administration

As if the specs weren't impressive enough, the administration scheme for the system is amazingly simple. Using a one-time program on Windows to assign the main Backbone Link an IP address then enabled me to configure the entire system using my favorite web browser. The Docklink serves up web pages ranging from status reports to node detection in real time using a Java applet. The system is fast and slick, and even enables you to change the box's IP address right from the admin web page (this turned out to be quite useful when my DHCP server caught up to the IP address I had assigned to the box and started causing network conflicts...).

The Drawbacks

As much as I wanted to give RadioLan a perfect review, it does have a few drawbacks that should be duly noted:

Scaling and Advanced Features

Although I didn't test any scaling issues (I never had more than 4 computers on the network), RadioLan seems to have a solid plan in that domain. Each wireless bridge can supposedly handle 128 clients, and it is possible to transparently roam from one wireless bridge to another.

RadioLan also offers an optional encryption option, which encrypts all wireless packets and prevents data sniffing (which is a much bigger risk when the network is wireless). I never really had a use for this, given that I use application-layer encryption with SSL-encrypted web pages, and SSH connections (instead of telnet). What this could be useful for, though, is a certain kind of authentication. Since the keys for encryption are set manually at every location, you can effectively prevent unauthorized users from accessing your bandwidth (which is otherwise available from the airwaves!).

Conclusion

Overall, the RadioLan system is basically a system you set up and then forget about. It just works. It lives up to expectations, and presents no additional hassle in system or network administration. While the radio range of the system could be increased (some systems claim 1000 feet...), the promises put forth in the docs are kept, and the overall experience is more than pleasant.

The biggest problem was the PCMCIA connector weakness, but I'm hoping RadioLan will take care of this soon. They recently have started offering a new PCMCIA-compatible system, the Mobilink, which is a one-piece antenna that plugs directly into the PCMCIA slot. This obviously doesn't have the connector weakness of the other system, but I haven't had the opportunity to test this latest equipment for reliability and ease of use. Overall, though, RadioLan makes a very impressive set of products.

Of course, this level of engineering comes at a hefty price. With the cheapest network interface coming in at over $350, PCMCI cards at $450, and Ethernet links at $800, this is not exactly a cheap investment. For a small office, though, using Radiolan instead of wiring up the walls with Ethernet offers a simple and easy solution that most probably ends up costing less in the end given the flexibility of wireless.

For anyone who has the budget and who is looking for small office networking, I highly recommend Radiolan over any wired network setup.

ben@mit.edu

Reader's Comments

RadioLAN wireless is CSMA/CA and is a peer to peer network. The CA(collision advoidence) is done by ack'ing directed Etherenet frames as they are sent. This allows a positive response for each frame, and unlike wired Ethernet provides for automatic retransmission of the Ethernet frame if it is not ack'ed. RadioLAN has been providing a full 10Mb Ethernet wireless products since 1996 and is available in over 20 countries around the world. In addition to the indoor LAN distribution product family, there is a outdoor point to point product for distances of up to 1 mile.

-- Hugh Tebault, June 27, 1999
A cheaper alternative, based on 802.11, might be "AirPort", developed by Apple and Lucent. More information can be found here.
I haven't had the chance to test it, though. I'm just repeating what the Apple marketing guys are telling me...

-- Edmund Weitz, July 30, 1999
HPUX O8i ACS 4 PQAs Y2K+ Y? Cost of bandwidth.

Will ACS clients ever exist on Palm Pilots. Well I can dream.

I can't wait for something cheaper than the current USD$1 per 3K of palm.net<->Palm VII transmissions. One such transmission unit is approximately 40 bytes upstream (from the pilot) and 360 bytes downstream uncompressed*. Scary huh? And since it's not a raw interface to TCP/IP (much is stripped, between you and those tiny radio towers on the hilltop is simply a few UDP packets floating around)--and a pseudo CGI GET, you're expected to get no spontaneous updates from the server. It's a Quid Pro Quo situation. Give something (a preset cgi request) then you get something back (latest cgi response).

* To help you visualize 40 bytes upstream (using hash characters to represent ascii text and spaces):

########################################

** To help you visualize 360 bytes downstream:

######################################## ######################################## ######################################## ######################################## ######################################## ######################################## ######################################## ######################################## ########################################

Note: since it's not pure info (but html mark ups and get requests as well, cry :(

-- Li-fan Chen, August 7, 1999

I just wanted to add some more recent information. As of Feb 2000, it is possible to set up a home wireless network using 11Mb 802.11 (HR) for a very reasonable price. I'm using lucent's ISA adaptor inside my desktop system ($60 for isa adaptor and $180 for the pcmcia card that goes inside) that's acting as my wireless bridge. The bridge is running linux 2.2.9 + pcmcia + wavelan2_cs driver available from lucent. Then my laptop, also running linux, but could easily run anything else, also needs a pcmcia card and drivers.

Total cost was only $220 for the bridge, and $180 per laptop (it helps that the laptop and adaptor was paid for by our lab). not too bad.

Another option is the Apple airport base station, a little more expensive, but adds a modem too.

cheers.

-- karan bhatia, February 21, 2000

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