[Thorian]

Carl Campbell
John Eddy
February 13, 2005

802.11n: Overview of a New Standard

Around the same time the IEEE (Institute of Electrical and Electronics Engineers) finalized the 802.11g standard for wireless networking in June 2003, they also informally assigned a group to investigate needs for a new standard, 802.11n (Shim-CNET). Task Group n was formed by the IEEE 802.11 work group in September later that year with the mission to develop a wireless standard capable of delivering “real-world usable throughput of at least 100 Mbps” (Ellison –PC Mag). The standard is hoped to be approved and ratified by the year 2006.

We already know enough about 802.11n (referred to as N throughout this paper) to know that it will provide some advantages, but developers are running into some possible disadvantages as well. The ultimate advantage of N is obviously speed. The idea here is that N can provide speed equal to the very common Ethernet protocol 100BaseTX and allow users (especially companies) to do away with physical wiring to each network client (Cox – NWF). This would leave physical wiring needed only to the WAPs (Wireless Access Points). However, many experts think this is unrealistic:

"Unless you are sitting right under the access point, you just don't get the maximum throughput," says Dewitt Latimer, deputy CIO and CTO at University of Notre Dame in South Bend, Ind. WLAN throughput falls off more or less rapidly the farther a client device moves from an access point. The drop depends on how much metal, wood, concrete, and other construction material is between the two devices. In addition, in almost every case today, an access point is a shared medium: whatever throughput it can deliver is divvied up among however many users connect to that one access point. (Cox – NWF)

Therefore, the only real advantage over current 802.11 a, b, and g standards is the higher speed. All of them have the disadvantage of throughput drop off in relation to distance from the access point and materials in the transmission path. However, range is not the only limiting factor for the 802.11 standard, as the extra coding required at the physical layer, effectively halves the throughput just by adding extra overhead. Meanwhile, another limitation specific to N is that it will operate on the 5 GHz band, making it susceptible to the same interference as other 802.11 standards. Also, as this band is narrower than the 2.4 GHz band, signal is more easily absorbed or reflected by environmental obstacles (Berlind – ZDNet).

Though final costs are difficult to determine so early in the standard we can compare current a, b, and g equipment costs to the costs of pre-N equipment for home users. Home and enterprise level equipment will cost differently but comparison on the home equipment level does give a feel for the overall price differences. Pre-N equipment is that which is made based on the core technology of N but before N is officially approved. Prices for Dlink and Belkin Pre-N routers are around $115. Network adapters that work with these routers range from $80 to $100 according to Pricegrabber.com. Currently 802.11g routers range from $35 to $55 while the network adapters range from $15 for notebooks to $25 for PCI slots for computers also based on Pricegrabber.com.

So, basically N is not much different except for speed and eventually pricing will begin to equalize for the new standard especially after N has been approved for a few months. The range of N versus a, b, and g is roughly the same though at 160 feet when 802.11g drops to 0-1 Mbps, N can still manage a throughput of around 9 Mbps giving it a slightly longer range (Ellison – PCMag). While 802.11b grants only 11 Mbps of bandwidth (theoretical) and A and G are capable of 54 Mbps (around 25 Mbps actual), N can deliver 100 Mbps of real throughput (bandwidth after overhead is subtracted). As for security of these various standards N will be able to handle everything from WEP to WPA which goes for A, B, and G as well so nothing in that department has changed. So, overall we can say that we are gaining little from 802.11n except for a considerable increase in speed and that it is debatable among experts whether this standard is even necessary.

Works Cited:
Berlind, David. “When you think WLAN, think ahead.” ZDNet. 08 Jan. 2003.
http://techupdate.zd...e/sto...2908271,00.html

Cox, John. “Wireless LAN throughput on the rise.” Network World Fusion. 26 Sep. 2003.
http://www.nwfusion....092980211n.html

Ellison, Craig. “Getting a Leg Up on 802.11n.” PC Magazine. 16 Nov. 2004: 38.

Shim, Richard. “802.11g approved, 802.11n is next in line.” CNET News.com. 13 June 2003. http://news.zdnet.co...ications/net...,2136013,00.htm