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How many CPEs can an AP support?

Posted: Mon Jun 18, 2007 12:38 pm
by nick52
Can anyone give me an answer, please?

I have to serve an area of 5-6 Km of diameter by an AP at 5GHz.
My idea is to use a RouterBoard 532 with 2 R52 miniPCI cards: one connetcted to an amnidirectional antenna (AP) and the other to a directive antenna.

My questions are:
1. how many CPEs (Stations) can I connect to this AP?
2. which throughput the AP can support? (and consequently the throughput of each one CPE?)

nick52

Re: How many CPEs can an AP support?

Posted: Mon Jun 18, 2007 1:24 pm
by normis
there is no theoretical limit, but in reality 20-30 should be optimal. the throughput will be limited by your uplink (most likely), not the RB532

Re: How many CPEs can an AP support?

Posted: Mon Jun 18, 2007 2:59 pm
by nick52
Normis,
in your opinion, is this limit due the phisical layer (radio link), not the performace of RouterBoad?

Re: How many CPEs can an AP support?

Posted: Mon Jun 18, 2007 3:06 pm
by normis
first of all, your uplink will not be able to provide so much bandwidth to all of the clients

Re: How many CPEs can an AP support?

Posted: Mon Jun 18, 2007 5:22 pm
by BurstNET
<< first of all, your uplink will not be able to provide so much bandwidth to all of the clients >>

You don't know that for sure.
We have dark fiber to some of our wireless POPs serving our city, connected to a multi-gigabit backbone at our NOC.
The radios are the limit for these POPs...not the backbone. ;-)

SMA

Re: How many CPEs can an AP support?

Posted: Mon Jun 18, 2007 7:53 pm
by nick52
Normis,
you have not answered to my question: is this limit due to the phisical layer (radio link) ?

nick52

Re: How many CPEs can an AP support?

Posted: Tue Jun 19, 2007 10:09 am
by normis
<< first of all, your uplink will not be able to provide so much bandwidth to all of the clients >>

You don't know that for sure.
We have dark fiber to some of our wireless POPs serving our city, connected to a multi-gigabit backbone at our NOC.
The radios are the limit for these POPs...not the backbone. ;-)

SMA
I thought he said he will have a wireless uplink. Software limit is 2007 clients, you will just have to try and see how many you can get there until you run out of bandwidth and CPU resources.

Re: How many CPEs can an AP support?

Posted: Thu Jun 21, 2007 6:12 am
by GTHill
It is a channel (PHY Layer) limit, not the units. Most of the time cheap AP's off the shelf will have the same throughput as an expensive Cisco AP. The difference is the consistency, features and reliability.

Figure about 1/2 actual half-duplex throughput for the respective data rate. 11Mbps data rate will get about 5.7 - 6 Mbps throughput, 54 Mbps data rate will achieve a max of about 20Mbps. These numbers are for standard 802.11 protocol, not proprietary links.

Gene

Re: How many CPEs can an AP support?

Posted: Fri Jun 22, 2007 2:25 am
by gerencia@e-digitales.com
In my experience in two of my POPs, with 45 clients, the uplink is very poor, i changed the omni with 3 sector and very good uplink.

Re: How many CPEs can an AP support?

Posted: Fri Jun 22, 2007 4:50 pm
by nick52
In my experience in two of my POPs, with 45 clients, the uplink is very poor, i changed the omni with 3 sector and very good uplink.
hi gerencia@e-digitales.com,
When you changed the omni with 3 sectors, did you connect the 3 sectors to 3 Wireless Cards of one only RouterBoard or did you connect each sector to one Wirless Card of one different RouterBoard and the 3 RouterBoards connected by selves by Ethernet?

May you tell us what is the throughput of the AP?

nick52

Re: How many CPEs can an AP support?

Posted: Fri Jun 22, 2007 6:06 pm
by gerencia@e-digitales.com
When you changed the omni with 3 sectors, did you connect the 3 sectors to 3 Wireless Cards of one only RouterBoard or did you connect each sector to one Wirless Card of one different RouterBoard and the 3 RouterBoards connected by selves by Ethernet?

May you tell us what is the throughput of the AP?

nick52

3sectors to 3 minipci compex 200mw band B (Not 5ghz) with one only RouterBoard 532 with daugther board and 4th minipci for WAN. And all clients can share 3mbps of internet and each one have 512kbps.

Dimas

Re: How many CPEs can an AP support?

Posted: Sat Jun 23, 2007 8:56 pm
by nickb
We start seeing diminishing customer experience at 30 to 35 CPE on a radio interface, using a mix of CB3 (prism) and LS2 (Atheros) client radios.

I have speculated that using all Atheros radios, all in G mode, may increase that density.