Wireless Hacks

Hack 65 Client Capability Reference Chart

A quick guide to what's what in the world of consumer wireless gear.

Wi-Fi has decidedly shifted from a niche market to a mass market in just a little over a year. As a result, there is a bewildering assortment of wireless equipment available on the market. While the various descriptions will dazzle you with the latest bells, whistles, and didgeridoos, most wireless hackery requires only the answer to a few key questions: How much does it cost? How much power does it put out? How sensitive is the radio? What other equipment will it communicate with?

Unfortunately, the answer to the first question ("How much does it cost?") is changing so rapidly that by the time this book makes it to press, anything I included here would be irrelevant. While new hardware is being introduced all the time, the specifications of existing hardware remain relatively unchanged. Table 4-2 shows the vital statistics of many popular radio cards.

For brevity, the table's Receive Sensitivity column uses the following convention: the numbers are the power levels required (in dBm) to receive data at 11 Mbps, 5.5 Mbps, 2 Mbps, and 1 Mbps respectively. Remember that these are negative numbers, so, for example, a rating of -94 is much more sensitive than a rating of -87 (by a whopping 7 dB!) A "*" means that the rating for that speed is unavailable.

Table 4-2. Common wireless client capabilities matrix

Name	Interface	Tx power	Rx sensitivity	Antenna connector	Chipset
3Com AirConnect	PCMCIA	30mW	-81 / -84 / -85 / -87	Dual MMCX	Prism 2.5
Addtron AWP-100	PCMCIA	20mW	-76 / * / * / -80	None	Prism
Cisco 340(AIR-LMC340)	PCMCIA	30mW	-83/-87/-88/-90	Dual MMCX	Aironet
Cisco 350 (AIR-LMC350)	PCMCIA	100mW	-85/-89/-91/-94	Dual MMCX	Aironet
D-Link DWL-520	PCI	30mW	-80/-83/-86/-89	Reverse SMA	Prism
D-Link DWL-650	PCMCIA	30mW	-84/-87/*/-90	None	Prism 2
D-Link DWL-650+(proprietary 22Mb)	CardBus	30mW	unpublished?	None	TI
EnGenius/Senao/NetGate(2511 Plus EXT2)	PCMCIA	200mW	-89/-91/-93/-95	Dual MMCX	Prism 2.5
EnGenius/Senao/NetGate(2011CD)	PCMCIA	100mW	-87/-89/-91/-93	Dual MMCX	Prism 2.5
Linksys WPC11	PCMCIA	25mW	-76/*/*/-80	None	Prism 2
Linksys WMP11	PCI	30mW	-82/*/*/*	Reverse SMA	Prism 2
NetGear MA101	USB	20mW	-84/-87/-89/-91	None	n/a
NetGear MA401	PCMCIA	30mW	*/*/*/*	None	Prism 2
Orinoco(Silver or Gold)	PCMCIA	30mW	-82/-87/-91/-94	Lucent	Hermes
ZcomMax(XI-325H)	PCMCIA	100mW	-92/*/*/-85	MMCX	Prism 2.5

Note that some client cards use minor variations under the same trade name. For example, the Cisco Aironet series can come with or without external antenna connectors. Units with AIR-PCM model numbers have permanent molded antenna connectors, while AIR-LMC models have external connectors with no internal antenna. Likewise, some manufacturers offer cards with different transmit power under similar names, but that have different model numbers. Be sure to check your model numbers before purchasing!

There is an interactive hardware capability chart available from Seattle-Wireless (http://seattlewireless.net/index.cgi/HardwareComparison). This chart is generally kept up to date as new equipment appears on the market, and can be particularly handy, since some manufacturers bury the technical details of their products in the back of the manual (if they publish them at all). If you have a piece of hardware that isn't listed, you can add it to the list yourself, and save other people the effort of digging around for the real specs.