Channel Planning with 40 MHz Channels

Channel Planning with 40 MHz Channels

By CWNP On 09/13/2007 - 5 Comments

Let's not even consider 40 MHz channels in the 2.4 GHz ISM band.  There can only be two non-overlapping HT MIMO channels in the 2.4 GHz band.  Considering the mess of protection mechanisms, competing 20 MHz channels, and the dozens of interfering non-WiFi devices in that band, 802.11n in 2.4 GHz is a lost cause from day 1.  Instead, let's consider the only reasonable (IMHO) enterprise-class 802.11n deployment methodology: 5 GHz.


40 MHz channels require dual adjacent 20 MHz channels for operation.  For example, channels 36 and 40 might be used together as a 40 MHz channel or perhaps channels 44 and 48.  When site surveying, we are doing channel planning for between 8 (UNII-1/UNII-2) and 23 (UNII-1 (4), UNII-2 (4), UNII-2E (11), and UNII-3 (4)) useable channels.  I'm leaving out the channel 165 5 GHz ISM channel as a consideration here.  It's hoped that most 802.11n equipment (especially enterprise-class equipment) will support all four of these UNII bands.  With 23 (or 24) available individual channels, 40 MHz channel planning should be a reasonable task.

The fun will come when there are existing 20 MHz channels in use by neighboring devices out of your control.  Planning 40 MHz deployments in the presence of 20 MHz channels that are auto-selected by a neighbor's WLAN controller's RF Management feature will be bonus fun.  First, their 20 MHz systems may cause your system to change to HT_MF mode, which will cause use of protection mechanisms.  Second, their channels may be configured such that you (or your system's automated features) won't be able to find an interference-free channel pair.  In fact, to design a good 40 MHz channel reuse pattern, you'll need no fewer than three 40 MHz channels (each consisting of a pair of 20 MHz channels) per WLAN infrastructure.

Can you imagine what the mess might look like if you have three WLAN controllers in a multi-tenant building, each using 5 GHz 40 MHz deployments with automatic RF management features enabled?  At a very minimum, where three U.S.-based organizations worked together on their design (which will never, ever happen), there would be 18 channels in use - three pair per organization.  That's not considering the individual 20 MHz channels that might also be in use here and there.  Yikes. 

This makes me think that companies championing the single-channel architecture MAY have a reasonable advantage in deploying somewhat-interference-free networks in 5 GHz (40 MHz) 802.11n networks, and even more of an advantage in the 2.4 GHz band (since two non-overlapping 40 MHz channels do not have to be used).  An 802.11n feature that SEEMS to give more of an advantage to the single-channel architecture than it does to the traditional channel-reuse architecture is Transmit Beamforming (TxBF).  TxBF cuts down on the bulk of co-channel interference by directionally focusing transmissions.  This is good for traditional architectures, but REALLY good for the single-channel architecture.  There's also the possible drawback that TxBF might cause clients to be sticky.

Organizations who already have a significant investment in 802.11a/g networks should consider the following before an upgrade:

1) As many clients as possible should be upgraded to 802.11n to get additional throughput benefits
2) Some 802.11n APs may need more power than is provided by 802.3af PoE
3) A new site survey may have to be performed
4) New cable pulls may be required

In summary, get ready.  Job security is on its way, and it's called 802.11n.

5 Responses to Channel Planning with 40 MHz Channels

Subscribe by Email
Britton Jones Says:
05/21/2018 at 02:24am
You will be asked to give more info such name, call, address, pay, account number. Citicards Login that could provide you various advantages and incentives as well.

neha sharma Says:
05/04/2018 at 07:26am
I am happy to visit here.I really like what you shared. I would like to share that I am working with Delhi beat escorts services which provide best call girls services in Delhi.Here you can find the cheapest and most beautiful girls for fun, if you want to get relax in your busy time life then you have to meet our call girls which help to make your night memorable.
Delhi Call Girls
Dwarka Call Girls

wiatmppgryar wiatmppgryar Says:
04/18/2018 at 03:41am
Nick Williams generates outstanding your home go

Philadelphia Eagles Jerseys PHILADELPHIA -- Any personal pc shows may be a infamous first-pitch swinger. That makes it no great surprise the fact that Reds reliever used her a good first-pitch breaking up shot during the eighth inning From monday overnight for Locals Loan provider Area. Torrey Mason Jerseys Quackenbush wished for Williams that will go in pursuit of, except for that time Williams couldn't. Tommy McDonald Jerseys She on the other hand did the trick on his own suitable 3-1 be counted, earlier than she crushed a good fastball that will right-center-field for that pinch-hit destroy your home go from a 6-5 victory.

Philadelphia Eagles It had become the main pinch-hit homer for Williams' work. Phillies magnified used this earliest save you within the couple of years by using a scoreless ninth. Timmy Jernigan Jerseys Reds catcher come to this earliest your home go within the couple of years during the 1 / 3 inning, tying this online game for 3. She was initially associated with any registration to your earliest start of the couple of years meant for southpaw, what person made it possible for your five carries on (a couple of generated) during this a couple of innings for job.   Any Reds bullpen did the trick five scoreless innings earlier than Quackenbush gave home set you back Williams. Terrence Brooks Jerseys MEMORIES THE FACT THAT MATTEREDHoskins, Kingery player Reed: Phillies placed fielder come to a good two-out, two-run your home set you back placed niche during the earliest inning alongside Reed to hand any Phillies a good 2-1 contribute. Stephen Tulloch Jerseys Rookie taken by using a destroy your home set you back placed during the following, this earliest Serious Little league your home go, to build it all 3-1.

NFL Jerseys Kingery come to a good 1-0 fastball a bit of fewer than 15 long (1. 22 your feet) up from the yard. Hardly any Phillies footballer have come to a good shot lessen up from the yard seeing that come to an individual fewer than 9 long (0. 73 your feet) within the dirt and grime survive August. Ervin dozens, Hamilton is not going to: begun any sixth inning by using a simple that will placed niche. That's exactly what stole following that can put on his own during scoring job. Stefen Wisniewski Jerseys Phillies catcher in reality used a good rocket that will following trust -- clocked any dispose of for 90. 0 mph -- however , Kingery have to any container tardy together with have hardly any possibility of indicate her. Sidney Jones Jerseys It all showed clearly highly-priced mainly because Ervin subsequently have scored at a two-out chopper out Phillies pitcher is the reason finger that will place this online game, 5-5. Alfaro savored certain redemption tardy during the inning anytime Hamilton used that will fico score with following at a undomesticated playing surface. Stefen Wisniewski Jerseys Alfaro slid that will return any shot associated with any registration together with used a good attack that will, what person put on to any shot mainly because Hamilton collided utilizing her to your 1 / 3 released.

Allan Olson Says:
04/11/2018 at 03:00am
Channel planning with 40 MHz channels and we are here to understand the channel. If you like this college review channel then this was good for us. But if we not like this channel then we can skip this channel and trying to find another way to get that channel.

Eva green Says:
01/21/2018 at 03:56am
we all love to play online games some list of games that is strategical game and suits you to play here Mahjongg dark dimensions free online among all the player is love only here to play online with top most selected games of mahjong games

<< prev - comments page 1 of 1 - next >>

Leave a Reply

Please login or sign-up to add your comment.
Success Stories

I literally just came out of the testing centre having taken the CWDP exam. The certification process opened my mind to different techniques and solutions. This knowledge can only broaden your perspective. Great job, CWNP, you have a great thing going on here.

Read More

Working through the CWNP coursework and certifications helped not only to deepen my technical knowledge and understanding, but also it boosted my confidence. The hard work it took to earn my CWNE has been rewarding in so many ways.

Read More

I want to commend you and all at CWNP for having a great organization. You really 'raise the bar' on knowing Wi-Fi well. I have learned a ton of information that is helping my job experience and personal career goals, because of my CWAP/CWDP/CWSP studies. Kudos to all at CWNP.

Read More