• As I am reading the CWDP a questions has arisen. Limiting a network to exclude some data rates such a 1,2 and 5.5 can greatly help a network in some scenarios. Especially for things like Vowifi.

    Until now, I see ubiquiti access points as being an inexpensive and pretty solid company. However, from what I have read they can't exclude some basic rates, that would seem to be a major drawback. So is the best that can be hoped for using a brand that can't exclude data rates to set it to mandatory 802.11n?

    Would there be any client adapter settings that could offset that deficiency?


  • In the b/g world, I have found that most SOHO routers only allow you to set a maximum rate, and not even a single one at that.   For example, 24 Mbps or less.

    Enterprise hardware like Cisco etal, allow you to include/exclude the rates you want.   Having said that, I have found Cisco "n" AP's that will not allow you to disable ALL of the g rates.   On those you must have at least one 'b/g' rate specified, along with some number of MCS rates.

    Some client devices also will not allow you to exclude a range, say 24 and below.   These will refuse to connect at all.  But some laptops I've seen will accept any combination of rates that the AP advertises.   

    Restrictions, like these, can make the kind of testing that I do difficult.

  • Thanks for the response Howard.

    It is hard getting experience with some of these things when the equipment is so expensive. I will say that I installed a pretty nice intel pro AC card in my laptop and it is interesting tinkering with the options it gives. Also gives some nice stats that I don't see with the cheapies.

    Out of curiosity what do you do? Analyst of some sort?

  • By Howard - edited: February 24, 2014

    Currently I work for a client device manufacturer.    Primarily PHY and  MAC level testing.  

    All of a/b/g/n, infrastructure, and Adhoc.  Some Bluetooth PHY.    Ump-tine variations of Windows, no Linux right now.

    Mobile and Stationary equipment.

    Years ago I installed SOHO equipment for homes and small business.

    That's true. Most client devices I have seen in the last few years don't give you the opportunity to change things.   I think most manufacturers have decided that users changing some parameters causes more problems than they fix.  It certainly creates more customer service calls.   

  • Hi there.

    I think the advice of turning off all speeds except one is not a good solution for VoFi. I do not know where this suggestion come from but it is mentioned in Cisco Docs. I know its increases the throughput in the cell but sometimes it is a bad idea.

    A VoFi handset running on 802,11b should have a chance to step down to a lower speed. Because when you are walking in and out of cells and turning your body back and forth the receiving signal level for a moving device change quickly and the handset may want to use a slower speed to not loose connection. I t may have to stay on a weak AP for a while until it has found a roaming candidate strong enough to move to,

    You are actually stopping the handset from using the chance to use weaker signals. Especially since you may often have the case where the AP is transmitting at higher speed than the handset due to its better radio.

    Same issue if you are removing a lot of speeds in OFDM systems.


  • I think the best course of action is to follow the Manufacturer's advice.

    However, that does assume that a proper site survey and provisioning, as defined by the same company, was performed.

  • By VoFi_Martin - edited: April 2, 2014

    Still it against the idea with having multiple speeds for resilience purposes. Low speed is not an issue really for VoFi due to the small frames and low bandwidth needed. More important to have a steady connection even if forced to use a low speed.

  • “basic data rate” is used to set the maximum cell size per AP, it is a basic function of WLAN design, it does this by determining the lowest data rate used for all management frames from the AP, so if you have a 802.11a/g/n AP and set the lowest basic rate @36Mb then all frames send from the AP will be @the minimum 36Mb; any STA that can see the frames but whose frames are received below 36Mb are typically not able to maintain association to that specific AP and roam.

    Adjustment of basic data rate is typically done to help STA’s roam.

    Using rates below 12Mb a/g rates in today’s design? , heck even using non-HT rates today would seem unusual. DSSS/CCK rates in use today?


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