Wireless Lan Notes

(The information here was gathered durring the Spring of 1999) (There is a more recent Slashdot article on wireless net working (Feb 2000)) <In light of the Slashdot article I've begun to update this page with new information.>

Warning. These are copies of my notes to myself. I have not tried any of these products at all. I am mearly providing links to suppliers of wireless lan products and comentary on publically available information. Some of the information I present may be wrong, or might not apply to all products. If you see an error please email me. I'll also mention that I evaluate everything from a robotics and Linux centric position. This is because I use Linux on most of my home systems, and I'm heavily into robotics. I am currently (Winter 2000) also looking at wireless technologies for connection to wearable computers, but have not updated the research yet.

It looks like we finally have affordable wireless lan networking hardware around the corner. Apple has recently introduced (July 1999) a product for their MAC iBook notebook. It's $99 for the card to go into the iBook (only works in the iBook) and $299 for the base station. The base station can be plugged into any network via it's Ethernet port or use it's internal 59k modem to connect with. Because of this low price I expect that there will be greater price pressure and greater volume for PC based products. Both will hel[p to drive down the prices. It also looks like for the short term, next 5 years, that IEEE 802.11 DSSS complient devices will be the most available. Currently most propducts comform to the 2mbps data rate standard, however with the introduction of the Harris PRISM II chip set this past winter, 5/11mbps devices will start showing up. Apple and Airport already have devices at the higher speeds. Others are sure to follow soon.

Most of the cards below seam to be implemented with the original PRISM chipset formerly from Harris, now from Intersil while the Apple Airport and a coule of the others are using the new PRISM II chipset. The PRISM II chipset is suposed to be much less costly to build a design around. Also it supports the 5 and 11 mbps data rates from the draft high speed extension to IEEE 802.11 that the original chipset didn't. The other thing I find interesting about the PRISM chipset is the support for it under Linux. The old PRISM chipset appears to have a good set of drivers that works with a few of the available PCMCIA cards, while support for the new PRISM II chipset isn't known yet. The PRISM II chipset may or may not use a different control interface, and deffinatly has a couple of differences around controling data rates.

It should be noted that Apple says that two of their iBook notebooks with the WLAN cards in them can communicate without the use of a central controlling HUB. Could this be used on other cards? I can see where this would be good for the home roboticist.

I've seen mention that there are multiple frequency sets defined in the IEEE 802.11 specification when using the ISM band. From the descriptions it seams that there are 12-14??? frequency sets in the band, and that you can setup your link to one of the available bands. I also have seen mention that not all bands are allowed in all countries supporting the standard. It seams that some of the devices are designed to allow use on multiple bands and some HUBS can bridge between bands. I've seen mention of a 32 device limit on a particular band.

The data rates are getting respectible enough that one may consider wireless lan hardware for communications between a baser computer and the onboard computer. Diagnostic information as well as current sensor inputs should be able to be sent over the link. It may even be possible to support low resolution and frame rate video. The data rates of the 2mbps products are high enough that one can consider supporting X-Windows over the link. The 5/11mbps of the newer chip sets should allow for full X connectivity. This is something I want if I go ahead with network connectivity on a robot. This would be especially good for communication to a portable computer with a heads up type display.

Use with PC-104: One could get a PC-104 to PCMCIA bridge (redially available), use a PCMCIA enabled CPU board, or use the ISA OEM card from Proxim.

WLAN List of Available Products (This table is in serious flux. I'm now detailing specific products)

Apple
Link	Description	Access Point HUB	PCMCIA	ISA	PCI	Misc	STD *	Spread Spectrum Method	Freq	Country	MAX Speed (bps)	OS Support	Linux	MAC	Windows 95/98/NT	Misc OS Support	Linux Driver	Notes
	AirPort Base Station	Et M56k					802.11	DSSS	2.4G	US Canada	11m	MAC		*
	AirPort Card					iBook iMAC MAC-G4	802.11	DSSS	2.4G	US Canada	11m			*

ZoomAir
	AP128	Et I					802.11	DSSS	2.4G		2m					W T S
	4000		Type II				802.11	DSSS	2.4G	US Canada	2m		OS		*		Linux WLAN
	4001		Type II				802.11	DSSS	2.4G	Europe Austrailia	2m		OS		*		Linux WLAN
	4005		+	*			802.11	DSSS	2.4G	US Canada	2m		OS		*		Linux WLAN	Internal Antenna
	4006		+	*			8002.11	DSSS	2.4G	Europe Austrailia	2m		OS		*		Linux WLAN	Internal Antenna
	4007		+	*			802.11	DSSS	2.4G	US Canada	2m		OS		*		Linux WLAN	External Dipole Antenna

Aironet	Many products with three differnet technology lines.						IEEE 802.11 DSSS, IEEE 802.11 FS										For some

farallon	PCMCIA Type II Card						IEEE 802.11 DSSS @ 2mbps					MAC, Windows 95, 98, NT

proxim	Access Port HUB, PCMCIA Type II Card, Design In Embedded card in ISA and PCMCIA interfaces						IEEE 802.11 DSSS @ 2mbps					ODI (DOS and Netware), Windows 95, NT

nokia	PCMCIA Type II Card, Access Point HUB, Access Point HUB with DHCP support						IEEE 802.11 DSSS					Windows 95, 98, NT					Linux WLAN

samsung	PCMCIA Type II Card, ISA Card, Access Point HUB wit Ethernet port						IEEE 802.11 DSSS					Windows 3.11, 95, NT					Linux WLAN

dbtel	PCMCIA Type II Card, HUB, Access Point Hub/Bridge						IEEE 802.11 DSSS @ 2mbps					Netware, DOS, Windows 95, 98, NT

gemtek	PCMCIA Type II Card,						IEEE 802.11 DSSS @ 2mbps					Windows 95, 98 NT

melcoinc

Bay Networks

webgear	PCMICA Type II Card, Parallel Port Adapter, ISA Adapter, Access Point HUB						900MHz Propritary, IEEE 802.11 FHSS @ 2mbps					Windows 95, 98, NT 4.0

alpha-tele	PCMCIA Type II Card,						IEEE 802.11 DSSS @ 2mbps IEEE 802 FHSS @ 1mbps

eumitcom	PCMCIA Type II Card, ISA Adapter, Access Point						IEEE 802.11 DSSS ISM band @ 2mbps IEEE 802.11 DSSS ISM band @ 11mbps					NDIS 2.0/3.0

* Compatibility: DSSS and FHSS are two different methods of providing the radio link layer between devices. They are incompatible with each other and actually interfere with each other. They use the same set of radio bands, but they work differently. DSSS is Direct Sequence Spread Spectrum, while FHSS is Frequency Hopping Spread Spectrum.

M56k = Modem, 56k baud
Et = Etherenet Port, 10BaseT
I = ISDN
W = Web based management
T = Telnet based management
S = Serial based management

Linux Software Support

www.absoval.com/linux-wlan/ - The goal of the Linux WLAN project is to develop a complete, standards based, wireless LAN system using the GNU/Linux operating system. What differentiates this project from the Linux wireless extensions and other Linux wireless projects is that we're basing everything on the recently approved IEEE 802.11 standard.
www.nwn.com/ -
Linux Drivers are available for Lucent Wavelan! Take a look at: www.fasta.fh-dortmund.de/users/andy/wvlan (complete source) ftp.wavelan.com/pub/SOFTWARE/IEEE/PC_CARD/LINUX/ (mostly source, but contains binary-only library)
www.hpl.hp.com/personal/Jean_Tourrilhes/Linux/Linux.Wireless.drivers.html has lots of information on the status of drivers for many different cards. It also talks about the different technologies used by different product lines.

Ham Radio Solutions

www.tapr.org/tapr/html/Ftaprfhss.html - if you're interested in a slower albeit longer range spread spectrum radio, check out the TAPR ham radio groups work. They have some very good RealAudio files describing the design decisions behind the RF and the digital/networking environment. Currently they only have two volunteers working on the project so progress is slow. The site also has good information on spread spectrum in general which will help you understand the controversy between dsss and fhss techniques. (Hint: the hams picked fhss because it has better noise resistance)

Links to additional information

www.nuge.com/~ss/ - Jay Nugent - WB8TKL Spread-Spectrum Pages
Bluetooth (www.bluetooth.com).
www.mindspring.com/~lfry/part15.htm - Spread Spectrum Device Compendium
bugs.wpi.edu:8080/EE535/hwk8cd95/witek/witek.html - History of Spread Spectrum
hydra.carleton.ca/info/wlan.html - Wireless LAN/MAN modem Product Directory
www.baltzer.nl/winet/winet.asp - ACM afiliated Wireless Networks Journal
www.tapr.org/ss/index.html - TAPR Spread Spectrum Pages
www.arrl.org - ARRL Amature Radio Relay League
www.zdnet.co.uk/itweek/brief/1999/18/wireless/01.html - "Conflicting standards cause interference on radio LANs" is a good article detailing some of the good and bad parts of FHSS and DSSS in the IEEE 802.11 specification.
www.wlif.org - Wireless LAN Interoperability Forum (WLIF). They have many good pages on the standards involved, plus a certification program.
{need URL} - HiperLAN - 17mbps, a European based standard for Wireless LAN. HyperLAN 2 - 25mbps
www.sss-mag.com/hamnotes.html - THE HAM RADIO SS NOTEBOOK
www.wlana.com/intro/standard/ - The IEEE 802.11 Wireless LAN Standard
standards.ieee.org/ - IEEE Standards
www.aironet.com/products/uc4845/uc4845.html

Companies

www.freewave.com/ - FreeWave, RS-232 Spread Spectrum data links, 115kbaud, available in enclosures and as OEM boards.
Transmitter and receiver modules: www.abacom-tech.com/

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