Hi all,

I've a WISP with 5 towers (access points where the clients are connected) and I want to increase the quality of my access points. Than I'm interesting in change the structure of this and I desire some sugestions to do this.

Today I have the configuration below:
- i386 PC motherboar
- 2 senao EXT2 Plus cards doing AP
- 4 setorial antennas (2 antennas in each senao card)
- 1 5.8 atheros card doing the PTP with my office.
- each senao card has a different SSID and a different channel.

What's the best configuration for the access points?

If I work with 4 cards (one for each setorial antenna) working in AP mode can I use the same ssid?
I'll have problems if I put 2 cards with the same ssid and with the same channel?

I need to improve the quality on my access points because the amount of customers is increasing and I want to maintain the quality that I've today.

All the suggestions and opinions to increase the quality of my access points are welcome.

Thanks in advance

Fabrício F:. Kammer
Conchalnet

You could do smaller sectors, 6 of 60° for example, each with its own card to allow the maximum number of clients per cell, in this situation you could have the same ssid but use different channels, depending on the distance back to back (a couple if meters, more if possible) you could even reuse channels, or use neighboring channels (on the antennas which are diametrically opposed at 180°), the antennas which border each other need to be as far apart as possible channel wise.

The only reason to use different SSIDs is to keep clients sectorialized, in this way, they wouldn't move between cells as easily as if the SSID was identical the entire way around.

Thanks very much NickW, You have a good idea with more sectors antennas

I'll wait the opinions of more mikrotik administrators to compare the different opinions about this.

Regards

You didn't specify what you mean by increasing quality. I would suggest a wireless system built for outdoor broadband with a MT router at each site. Systems like trango, alvarion VL, moto canopy are good quality and beat home-built stuff all to pieces for packets per second, ease of install, hardware reliability, spectrum use, etc.. Antenna choice at your tower is important too, as some are a bit optimistic regarding their gain, sectors can have weak front-to-back ratios, etc...

HI JP, thanks for you answer

I think in maintain the quality of the signal level and the speed of the customer's link with my AP that I've today, but with the capacity to connect more people.
The packets per second is an important point, because this is a serious problem in a 2.4 card, but I don't think in change my Mikrotiks APs because I've a lot of controls on it (firewall, queues, etc).

I just want some sugestions about how is the ideal structure about the SSIDs and Channels for a tower with sectors antennas.

I agree with you that the right choice of the antennas is very important than I want sugestions about the ideal sectors antennas, don't about the manufacture of the antennas because I've to buy antennas that are allowed in my country. I need of indication of the best specifications of than.

Regards

A few suggestions:

- Don't complicate things - use bridging in favour of complex routing
- Make sure, that your backbone is perfect - lots of cpu-power and minimal noise
- Have enough basic high quality bandwidth avaliable
- If you are in a noisy area, then use horisontally polarized antennas
- Use high power sectorial antennas (>= 17 dB) and high power radios (>= 400 mW)
- Avoid mixed environment - all clients must use identical cpe-devices
- Don't centralize - use more, less populated towers (20 - 30 users per radio max)
- Use "G-only" - if you must use 2.4 GHz
- Try to make p2p-traffic slow and erratic (you can't avoid it)

If you find your way to accomplish this, you will be a successfull WISP.

Good luck in wonderfull Brazil

Regards
KimC

Hi KimC,

Thanks for your answer. Today I can't change the polarization to horizontal and the protocoll to 802.11g, because I have at about 500 customers installed and working.

Today I'm making p2p traffic control and I'm limiting the bandwidth of my customers. This is working fine I think.

I just want to prepare my structure to the expansion, because we are with good sales.

All my backbone is working in 802.11a and I've a very good bandwith on its.

I won't able to use 400mW radio cards in Brazil because we don't have radios homologated by the governement with this power and I don't like to use a lot of power, I prefer use less power as possible. In this way I don't generate interference to another towers mine.

Do you think that high gain sectoreal antennas is the ideal? I was thinking in use 12dBi antennas. What do you think abou this???
Today I'm working with 8dBI omni antennas in all my towers (5 towers) and I don't have problems with the quality of the signal. I'm not afraid with the quality of the signal, but the bandwidth (in kbps e pps) that the radios will support!

Another think that I'm curious is about the ideal configuration of the 4 channels in the same tower. How is the ideal distribution of this?

Today I'm using PC i386 motherboards with AMD processor to do the AP. The cards are Senao NL-2511CD Plus Ext2, with Prism chipset in my towers.
Can I put 4 wireless cards in the same machine (one for each sectorial antenna)? Or is the best way I use two machines with 2 cards each one?

Thanks for the "wonderfull Brazil". I like of it very much too!!!

Regards

Fabrício F. Kammer
Conchalnet

OK - more details:

A low-power card with an 8 dB omni G-only can be a good solution. It gives you lots of reflections, and in many cases a very good short distance coverage. However - nothing beats "brute force"... ie high antenna gain at radio power - if you need NLOS or long distance.

It seems, that you are doing the right thing with your AP's. A 386 is ok - but if avaliable, use more cpu. And if you must use low power radios, then the best choice is R52.

You can easily use same ssid on a sector config. The CPE's are using the MAC's and the S/N. But you must use different channels.

You may not be able to change standard on existing cells. In stead, consider to make new cells with a better standard for new users in parrallel with your existing. It will be possible to do this in your existing towers as well.


And regarding "wonderful Brazil" - to my experience, even the most lousy brazilean winter beats our northern summer I hope this is the case this year too ?

Regards Kim

Thanks again KimC

I like of your sugestion to create a new structure in my tower with a new tecnology (802.11g). This sounds well! But I've a doubt: The 802.11b and the 802.11g working in 2.4Ghz. Wont I have interference between the two structures in the same tower?

Another think that turn me afraid is about using 802.11g for outdoor connections. I read a long time ago that if I use 802.11g my card will support less customers. That I can't put the same number of 802.11b customers in a 802.11g card. Is this right?

Best regards

Fabrício F. Kammer
Conchalnet

Hi Fabrício

first - you can easily have more 2.4 GHz channels in the same tower, as long as you keep them 3 or 4 channels apart. This is how you make a sectorized tower. Just make sure, that you use different ssid for the two standards.

And to get the best performance, both AP and clients must be set to G-ony.

Regarding the number of concurrent users. G-standard supports real bandwidth of abt. 20 Mbps compared to B-standard, which at most handles 5-6 Mbps real traffic. This is the real limitation, and you gain a factor 4. The theoretical number of users per radio is the same.

By moving to G, you get other advantages as well. The most important is very low latency and much more reflections - our experience is NLOS within 1 km with good antenna and radio.

Regards
Kim C

Thanks KimC

I'll try to change the standard that I'm using in the new structure. I'll keep my actual AP with the omni and put a new AP with sectorials antenna working in 802.11g.

Regards,

Fabrício