Commercial Wireless Network - Comments/Suggestions?

[omega1]

Hi all,

A collegue and I have started up what I beleive is called a WISP (we have set up a wireless network and intend to sell bandwidth).

We are using a D-Link DSA-3100 gateway and currently have 2 D-Link DWL-2100AP access points, the first one, in access point mode, has a D-Link 18db gain antenna and the second access point (set as repeater) has a 120º sectoral antenna and a 3 watt bi-directional amplifier connected.

We intend to simply add access points as and when they become necessary to improve and extend coverage.

Mainly we want to attract long term users (on a monthly basis) and adding these users to the network seems to be easy enough, through the DSA-3100 gateway, we simply bill users on a monthly basis, and if they do not wish to continue, we delete the user on the gateway.

I have two questions;

Firstly, what kind of limitations are we likely to run into expanding this network by simply adding extra access points and high gain antennas?

Secondly, how could we enable the system we currently have to cater for short term users (hourly, daily) and integrate a payment system (Paypal or other credit card processing website) taht could deal with these short term users automatically.

Other comments and suggestions to look out for would be greatly appreciated.

Thanks for your time.

[M/Q]

Is this the topology? And sorry in advance as you are not going to like this post.

DSA-3100
|
|- Ethernet cable
|
>- DWL-2100 (AP mode with 18dBi ant)
....<>
....<> wireless signal
....<>
.......>- DWL-2100 (Repeater with 34.8dBm amp and sector ant)
..............<>
..............<>
...............>- Clients

If this is so and I understand it correctly, you are running an illegal setup. I feel it is important to mention this. You are out of regulation with any sort of antenna at 35dBm (3 watt). 30dBm (1 watt) is the max allowable power rating at any point to point or point to multipoint link in 802.11. Also since you are running a point to multi point link with the amplifier it will only allow you to use a 6dBi gain antenna at the power rating of 30dBm.

I find this excessive and disturbing as you are most likely affecting all sorts of wireless systems in the vicinity of that device. It is RF pollution and not according to FCC regs for an unlicensed RF emission. I suggest you read this simplified paper on the FCC regulations for 802.11 before continuing your venture. If there is a 802.11 savvy person in the area being painted they may report you.

http://www.lns.com/papers/part15/Regulations_Affecting_802_11.pdf

Since you are a business venture, it is important that you follow the rules or it affects everyone and then the .gov's will make changes that typically reduce the benefits to all concerned.

One other important issue is that these EIRP rating also require that the radiator system be certified by the FCC. If you just threw together a system without any concern for that, it is another regulation violation.

Sorry, but I find it bothersome that business ventures are started without any regard for regulations and others. Enough rant.

I also find it strange that you are asking these kinds of questions, as indefinite repeating is not a good idea. In fact a single repeat is not a good idea as with each repeat your bandwidth is cut in half. Also you are not going to be able to use WPA as that is not workable in a repeat situation as of yet. And in most business ventures bandwidth is a critical factor. All WISP's have either wired or wireless backhaul links and do not repeat just for that very reason. I suggest some research on the subject.

[omega1]

Hi,

Well thats told me! Thanks for the info, and the 'pointers'. This is one of the reasons im asking the questions.

The topology you indicated is currently the correct setup, we are adding a third AP next week which will repeat off the second repeater.

In your comment 'Also you are not going to be able to use WPA...' excuse my ignorance on the terminology, what is a WPA?

I will have to check the power and antenna limitations in my country.

Thanks for the info.

[M/Q]

I must apologize, I make the wrong assumption about location some of the time. I am afraid though that most the rest of the world has tighter restrictions that the US. Let me know where you are located and I can check it out.

Again do you realize that the bandwidth will really suffer from that? What do you envision as the number of users and bandwidth/QoS you are supplying?

Are you not using any encryption? WPA is the best form of encryption that is available on most newer devices. If you are not using it, then the clients are in serious jeopardy of having their traffic sniffed and data/username/passwords stolen. It is not a wise business decision to offer this service without some kind of encryption. I certainly would not use it.

[omega1]

Hi, thanks for your answers, especially about encryption. I will do my homework on this subject, I agree that it is a very important issue

I am in Spain.

We are using a DSA-3100 which allows 50 concurrent users and up to 250 accounts so this will of course be our limit. At the moment we have a 600k/4Mb (up/down) ADSL line which we can upgrade to a 600k/8Mb ADSL line, and if necessary invest in a load balancer and combine two or four ADSL lines. We will monitor the traffic on the lines at all times and if necessary increase the bandwidth if traffic becomes an issue. With the regards to the amount of users we would like, obivously the maximum amount that we can handle!

With regards to bandwidth being cut in half, is this the network bandwidth between the AP's? For example, if we are using DWL-2100AP's the network traffic is 54Mb so each time we repeat we lose half the bandwidth? IE: 54Mb, then 37Mb, then 18.5Mb, etc?

Thanks.

[M/Q]

Well it is a lot worse than that.

First wireless is simplex by its very nature therefore will automatically have half of the TBW (Throughput BandWidth) of a wired link, because a wired link is duplex, or can send signals both ways at the same time so it indeed achieves the advertised bandwidth (BW).

Also wireless requires a great deal more management so that overhead comes into play. For an example under perfect conditions a 802.11g link will never get over 25-27mb/s TBW. Encryption will also play a part in that and even reduce it more. Device incompatibility between vendors and more to the point how they handle encryption comes into play as well. All of these lower the TBW that is expected by people who have every right to assume that they are going to get 54mb/s TBW.

This article explains it quite well.

http://www.mobilityloop.com/index.php?option=com_content&task=view&id=22&Itemid=26

So you only have 27mb/sec on a perfect link using 802.11g to begin with. Then for every repeat you have to cut that in half. So your first repeat is 14mb/sec and so on. That is why repeating is an easy way to roll out WiFi, but businesses are not doing it, they use different channel or band for the backhaul. Trust me, what you are doing will end up being replaces and costing you more money.

Also you are really illegal, in Spain the maximum power ratings for indoor and outdoor are only 100mw. Most of Europe is the same way. They are much more emphatic about it over there as well, because they are aware of the RF pollution potential.

[omega1]

Hi again... thanks for all the replies and comments...

We are really starting to think that we're doing something seriously wrong here, and looking for comments suggestions...

As mentioned earlier, we have setup the following:

DSA-3100 Gateway (192.168.0.1) which assigns users an IP through DHCP. This is wired to the first AP, a DWL-2000AP in AP mode (192.168.0.2).
Then we have another DWL-2000AP in repeater mode (192.168.0.3) and a third DWL-2000AP (192.168.0.4) that repeats from the second DWL-2000AP in the line.

When checked independently, they all seem to be able to communicate Ok with each other, but when we try and use the system, we get all kinds of problems, AP's not seeing each other, signal dropping out, not reaching the getway to get the login page...

We are seriously considering chucking in the whole thing as we are having nothing but problems with the whole system.

Have we started off on the wrong road with this? What do other people use? I understand that the D-Link equipment is mainly for home use and there are lots more professional equipment out there.

Maybe someone could give an example of what could be used for our intended setup?

We intend to serve no more than 50 simultaneous users (hence choosing the DSA-3100) in a 6km radius (the terrain is difficult with mountanous areas and buildings) I guess we could need 6 or 7 AP's in total.

Since our intention of setting this up, and obviously spending a certain amount of money already we have since learnt that we need all kinds of stuff (backhaul, etc...).

Any relevant info would be gratefully aprreciated.

Thanks

[EastCoastWiFi]

I'm not sure what Spain's regulations are for 900mhz equipment but it sounds like that might be your best approach. Take a look at Trango, Motorola Canopy or Alvarion for some ideas. It honestly sounds like you need to go back to the drawing board. You need to have a good RF and network person before you start this venture. Don't make the mistakes most do and try to run it by the "seat of your pants" you will get burned. In other words, if you have to ask the questions you are asking... you are attempting something that will at best be a hobby and not a business by a long shot.