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Community Member

Site Survey Theory .... All Comments, Thoughts, and Theories are welcome

Hello All,

I am seeking opinions about a survey methodology that was told to me today.  I have my own thoughts about it but I just want to make sure I'm not off base so any help is greatly appreciated.  The requirements for the wireless network are as follows:

- Data and Voice

- Clients will utilize all bands but newer devices will be pushed to 5GHz 

- Clients are laptops and iPads right now but the future goal is to implement BYOD


So, here is the methodology that was told to me ... "We survey only in the 5GHz spectrum because if you have coverage in that spectrum (5GHz) the coverage in the 2.4GHz will be the fine or even better than that.  Therefore, we feel comfortable not capturing the data in the 2.4GHz spectrum." 


Thoughts about the above statement are welcome!!!





Cisco Employee

The essential question for a

The essential question for a high-density design is how many channels for each band will be needed to match the client base? This can be a tricky question since even dual band capable clients do not always select the faster 5 GHz band. Since bandwidth in 2.4 GHz is going to be limited, 5 GHz must be relied on to reach the goal.

Dual band adapters have been shipping with most laptops for some time. This does not mean that every laptop is a dual band client, but many are. Simply having a dual band client does not guarantee that it will choose 5 GHz over 2.4 GHz. The Microsoft Windows operating system defaults to a Wi-Fi channel search that starts with the 5 GHz channel 36 and continues searching through all of the 5 GHz channels that the client is capable of. If no 5 GHz AP is found then it will continue the search in 2.4 GHz starting at channel 1. Unless the Windows default is changed or the user has chosen a third party Wi-Fi utility to set spectrum preference to 2.4 GHz, the client radio will first try to associate to a 5 GHz AP. Apple Computer's latest release for Atheros and Broadcom chipsets also searches 5 GHz first.

The Cisco BandSelect feature enables the infrastructure to optimize these types of client connection choices. Where possible, it helps make sure that devices are attaching to the 5 GHz spectrum channels where interference sources tend to be significantly lighter. A much greater channel selection leads to the alleviation of bandwidth challenges.

Tablet computers and smartphones have begun entering the market at a staggering rate. The vast majority of smartphones shipping today operate in 2.4 GHz only. While many of them are 802.11n clients, of these most have implemented a single input single output (SISO) rather than Multiple Input, Multiple Output (MIMO). A SISO device is only capable of supporting MCS7 data rates, or 54 Mbps.
Community Member

Great point ... I didn't know

Great point ... I didn't know that clients actually start in the 5GHz spectrum when the scanned.  I thought they would start in the 2.4GHz first.  Thank for that bit of information.


I totally understand the benefits of 5GHz and all I just think when you're doing a survey in a building that doesn't have exisitng wireless you should survey both spectrums and not just assume one will cover both.  We all know that they will in fact look different whether the client choose to associate to the 5GHz side or not.  How can you justifiy the coverage of a 2.4GHz client that has issues if you only did a survey for the 5GHz side?

Hall of Fame Super Gold

One of my main reason why I'd

One of my main reason why I'd always do a survey with 5.0 Ghz is the penetrating values and the distance covered by 5.0 Ghz.   


I always tell clients to survey with the notion of implementing wireless voice.  I explained to them that when using voice telephony over wireless, the handsets are very sensitive.  


Makes sense to them. 



Community Member

Leo, So, do you totally



So, do you totally exclude the 2.4GHz Spectrum during your survey because your preference is 5GHz?  My thought is that because there is a possibility of having client in both spectrums you should still survey for both and not just assume that because 5GHz has "great coverage" the 2.4GHz side will to!  With AirMagnet allowing you to utilize multi-adapters its not like it take more time to do both spectrums now so for the sake of knowing the coverage that I'd be getting is why I think just doing one and not the other is a bad idea.



Hall of Fame Super Gold

So, do you totally exclude

So, do you totally exclude the 2.4GHz Spectrum during your survey because your preference is 5GHz?

The people I deal with, doesn't care if we have (or not) wireless.  What they care about is they can "brag" that we have wireless.  They are the sort of people who go into posh restaurants and read the menu from right-to-left.  They don't care.  


When I start telling them that I want their wireless to have "voice-grade wireless coverage" and tie this with "because voice handset are very sensitive", they just drop their guard and let me go free.  


At the end it works well for everyone.  wireless in the sites I've visited has remarkbly improved and the pencil-pushers and bean counters think they're saving a mint (not really, but who's telling them).  Win-win for all.  :)

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