Re: 802.11g vs 802.11n



~ jrb wrote:
~ > I am trying to figure out if going to 802.11n from an 802.11g is
~ > really worth it. My internet service is listed as being upto 7MB. Any
~ > thoughts on the switch?

~ Even 802.11b at 10 Mbps would be adequate for a 7 Mbps internet connection.

No it would not. The maximum nominal signaling rate of 802.11b is 11Mbps.
However, the 802.11 MAC layer has a lot of overhead, so even with a perfect
11Mbps 802.11b physical/MAC layer, this will translate (at the IP layer)
to a best case throughput rate of 5.5 - 6Mbps.

So, 802.11b would be a bottleneck for a 7Mbps Internet connection.

(Terminology note: when I say Mbps, by that I mean MegaBITS per second,
where "Mega" denotes one million [1,000,000].)

~ 802.11g is rated at 54 Mbps and would be useful for faster file
~ exchanges within your own network. While it uses ODFM modulation, it is
~ more robust (more reliable at longer ranges and less with than optimum
~ signal levels), that advantage is lost as it requires more than twice
~ the signal level for the higher speed.

802.11g OFDM is more robust, and with a perfect 54Mbps nominal signaling
rate will yield an IP layer throughput of up to 27Mbps or so.

~ Locking down 802.11g to 10 Mbps
~ would give you a very reliable wireless network.

10Mbps is not an 802.11g rate. You could cap 802.11g at the 24Mbps
signaling rate which would give you a maximum throughput of about
12Mbps, which should be sufficient to prevent the wireless link from
being a bottleneck for your Internet traffic.

However, if there are 802.11b-only clients present in your cell, then
the 802.11g protection mechanisms may reduce your maximum throughput,
such that your nominal 24Mbps signaling rate may no longer be sufficient
to yield 7Mbps of throughput.

Therefore, I would probably stick with the maximum 802.11g rate of
54Mbps, unless you have reason to be that the clients and/or APs are
doing a suboptimal job of rate selection and would therefore benefit from
a rate cap.

~ 802.11n could be considered an upgrade to 802.11g in terms of robustness
~ and range.
~
~ If your 802.11b networks works fine the way it is, there's no advantage
~ in spending the money to move up to 802.11n.

Roger that.

References:

Capacity Coverage & Deployment Considerations for IEEE 802.11g
Cisco whitepaper
http://www.cisco.com/en/US/products/hw/wireless/ps430/products_white_paper09186a00801d61a3.shtml

When Is 54 Not Equal to 54? A Look at 802.11a, b, and g Throughput
Article by Michael Gast
http://www.oreillynet.com/pub/a/wireless/2003/08/08/wireless_throughput.html

Aaron

.

Relevant Pages

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