Sinister WaveLan

WaveLan

WaveLan is a copyright of Lucent, and is their name of the wireless ethernet product line that was first an NCR product and then and AT&T product. It is also known as the DEC RoamAbout.

This page was written before the current 802.11 specification was created. Since that time, Lucent has discontinued the older, proprietary gear refered to in this page. Unfortunately, they continued to use the name Wavelan on their 802.11 gear for a time. They then renamed their 802.11 equipment Orinoco, and finally renamed the whole division of the company Avaya. Personally, I find this name game annoying and confusing, but it seems to be very popular with corporate giants these days.

The WaveLan comes in ISA, MCA, PCI, and PCMCIA versions. They operate on two bands: 915 Mhz and 2400 Mhz, using Direct Sequence Spread Spectrum (DSSS).

Spread Spectrum is a relatively new and somewhat complex radio technology that involves spreading the signal out of a wide portion of bandwidth, the original signal is mixed with a larger pseudo-random sequence. The receiving end strips away the pseudo-random sequence and "votes" on the results, majority winning for that bit. The result is a modulation method quite impervious to interference, either natural or man-made.

The WaveLan operates at 1.5 MBPS, half-duplex, in a carrier-sense multiple-access environment. It is license free, operating under the FCC Part 15 rules limiting power output and antenna height for such devices. Typically, a small "rubber duck" antenna is attached to the back of the device. However, with a decent antenna, such as a 10 element beam antenna, extending its range far beyond the 800 ft. it normally has. It has been used as an internet backbone in Latvia. Distances over over 6 KM have been achieved, using high-gain antennas, and with direct line-of-site orientation.

Problems with the WaveLan:

Cost - The retail cost of these cards was high - about $400-$600. We were fortunate enough to find a source that had used cards for $125 several years ago. More recently, these cards have appeared on ebay for a fraction of that cost. I suspect these will be in flea market dollar bins before long.
Power - Though a decent antenna can extend the range quite a bit, the WaveLan was designed for limited distances and is therefore a low power (100 mW) device. It is theoretically possible to build an amplifier to boost the power, but any design needs to be able to pull a signal from the WaveLan itself to be able to switch from Transmit to Receive and back again.
Security - Though Lucent touts the WaveLan as a secure device, it is not in fact very secure. It uses Direct Sequence Spread Spectrum as its modulation method, which could be very secure, but this security was crippled by the use of the same spreading code on all WaveLan cards. This means that although it is fairly difficult for a random eavesdropper to find, let alone decode, a WaveLan signal, it is very easy for another WaveLan user to do so. If you are thinking of that you could change the spreading code, be aware that it is inside one of the proprietary chips itself, and is virtually impossible to modify. This was probably done at the insistence of the US Government, which wants to be able to listen to all of its citizens transmissions. While Lucent does provide a selectable Network ID, there are only 65,280 possible codes, and it would be fairly easy to write a program that tries all codes in quick succession until the proper Network ID is found. Hence, the radio link-layer of the WaveLan is not very secure. Some cards come with a DES or AES implementation, of unknown key length and robustness. Our cards did not. So we suggest implementing some encryption and authentication on top of the WaveLan architecture, such as IPv6.
Legality - In the US, these devices are licensed to operate under "Part 15" of the FCC rules, which limit the size of the antenna and the power output. Modifying the antenna and power output would put the device outside of the Part 15 rules. Fortunately, Licensed Ham Radio operators are also allowed to operate in the same 915 Mhz band at higher power and with any antenna. But Amateur Radio is restricted to non-commercial transmissions.
Drivers