CWNP CWNA – Fundamentals of Site Surveys

1. Fundamentals of Site Surveys

In this module. We’re going to talk about something that truly is important. I’ve mentioned it a lot. It’s the fundamentals of site surveys. So we’re going to talk about some of the interviews that we’re going to go through, the type of information you’re going to collect, the documents, reports, and some of the vertical market considerations, basically meaning what type of company and business that you’re trying to support.

2. WLAN Site Survey Interview Part1

So do you need a site survey? I shouldn’t even have to ask that question. If you’ve been listening to me through this course, you know. Yes, you do. Because even if it’s a small shop, you’ve got a plan for the types of applications, the type of capacity and coverage, maybe even future growth, making sure you’re not wasting money by the misplacement of access points.

And so even for a small place now, as a house, I know a few people who have a lot of money, apparently, and they have big houses, and they can buy an access point like I would for my smaller little fixer upper. And it covers my house just fine. In fact, my neighbors can use it. Well, maybe they tried, I don’t know. But even for a home of that size, you might need two or three access points and maybe some sort of wireless bridging to get to your Internet connection. It’s just not unusual. And doing the planning saves you the money and hopefully gives you the capacity for growth.

3. WLAN Site Survey Interview Part2

Now, the technologies for a lot of us at home have been around since 90, 97, but there was a lot of misunderstanding because it was new or misinformation. But instead, back in 97, those people who always wanted to be on the cutting edge or what did they say? The bleeding edge, they would just start putting these wireless access points in with kind of a plug it in, turn it on mentality and then say, ooh, cool, right? It was working the way they had thought it would work. Where I live, there was a little government agency, not very big, and I went there, by the way, to take care of a firewall problem.

But they told me that ever since they put this wireless access point in, the firewall was blocking all the traffic. I didn’t get it. It wasn’t it wasn’t a coincidence. But they follow that mentality. They literally put the access point on top of the firewall and said, well, it’s not working very well in the building either. Again, no survey, no planning. plugged it in, turned it on.

4. WLAN Site Survey Interview Part3

So we need to do some questioning, interviews. The first part is to say, what’s the purpose of the wireless land? Why do you need it? In the early days, a lot of people were afraid of the wireless land and as they should have been. We didn’t have security down like we do now. But if you had a shop that might be 30,000 sqft in size, where you’ve got machinery out there and you need to don’t have internet connections, we just weren’t going to string all that cable in there. It usually didn’t work. So you might say, well, the purpose of the wireless land is for this area of the building to have connectivity. It’s just a matter of there ought to be a plan.

So as long as you have an understanding of what the needs of the wireless network are, then hopefully you’re going to have a better designed wireless network. Always remember, just because it sounds new, just because it sounds really cool, we just don’t go buy stuff and put it in for fun. You’ve got to find out what the business needs are. At the end of the day, the goal is to make the business more profitable. That’s how they run. Government agency is a little different, right? They’re not for profit type of company. You got to know what the business needs are and if wireless land technology is even going to help them. You’ll have to know who’s going to be using the wireless lan. So ask about those questions so you know how to plan again, the capacity and the performance.

5. WLAN Site Survey Interview Part4

The next step then is to begin asking all the necessary questions for doing your site survey and designing the wireless network. Now, the final design of a wireless lan is completed after the site survey is conducted. Now, you might have some preliminary ideas about the design of the capacity and coverage, but there are many tools that you should use to make sure that you have a better understanding of how to build.

This should have with you a copy of the buildings floor plan at least. Now a floor plan will show you where offices and doors and stairs they’ll hopefully tell you what the walls are made out of, but they’re not going to tell you where the desks and the cubicles and all that stuff is. Put that in there because that’s going to help you better with these software tools. Know where your rf coverage is going to be.

6. WLAN Site Survey Interview Part5

So the users and device density always important. We need to ask these questions so we can say an access point will give you the coverage, but you have 50 people there. That’s too many. So I’m going to lower the power down so they don’t have as big of an area. I’m going to put another access point close by so I can get to all 50 people without overloading any one access point. That’s just things that we have to ask as we go through there. Now, the normal questions are about that what I just talked about, the capacity. The other questions might come in like, are

there parts of the building that you don’t care if they have wireless connections? If somebody’s going to take the stairs from the second floor to the first floor, do they need to have wifi coverage in the stairway? It seems like an easy enough question asks. Questions don’t make the assumptions as far as what you put in there, but we want to make sure we have a good ratio of access points to the devices as well as what the coverage is going to be. I might also ask what time of day is going to be the busiest for the network. So that peak on and off use might also help me in planning.

7. WLAN Site Survey Interview Part6

Oh, great question. Ask. Do you already have wireless? If so, tell me about your existing transmitters. Where are they? Are they out of date? Are they going to work? Do I have to be backward compatible? Where are other transmitters like microwave ovens, cordless headsets, bluetooth devices, anything that can cause interference? So part of a site survey might also be looking to see how clear the air is. And then we have to ask questions. How portable or mobile are the users going to be? Because those are ways in which we can plan for whether or not we have to get other external devices, like a land controller, to help you get from one part of the building to the other without losing connectivity.

8. WLAN Site Survey Interview Part7

Now, in today’s world, unless you’re moving into a brand new building, there’s probably some already existing wireless lan infrastructure, and hopefully they have an existing site survey that you can work off. Chances are they don’t. Site surveys weren’t popular back in 97 or 2000 or 2001. I mean, we just didn’t think about that like we do today. Up to of maybe 40% of the companies might have some of these site surveys, but that’s about it. So that means you might have to conduct a second site survey, and if it’s been there for a while, the floor plan they use, did it change? Did they add new desks? Did they create new walls to create somebody a new office? Because they complain about not having one? Whatever the cases, make sure it’s still up to date.

9. WLAN Site Survey Interview Part8

So hopefully I’ve already told you that the usual purpose of a wireless lan is to give client mobility, to give you access to the access point connecting into the preexisting wired network, as seems to be the case now, right? We’re getting fewer and fewer wired clients.

So part of that is to ask the question is how are you going to integrate the wireless network into your existing wired network? Because there ought to be a plan for the security about new people coming in and connecting into a part of your network that might not be ready to support them or maybe have things that are very confidential.

So you have to start planning about segmentation right vlans and that type of stuff. And again, find out if roaming is required. It takes a lot more to do roaming. It’s not hard, but it takes more work to plan it. It’s takes a little bit more of equipment to be able to do that as well.

10. WLAN Site Survey Interview Part9

Now, access points, believe it or not, need electricity to work. And so we have to ask the question, how are we going to power those up? I told you that many of the times we actually mount those access points into the ceiling, or if you have a fault ceiling will move one of the panels and put it up. But how do you get electricity to it? Because usually when I’ve crawled into ceilings, I don’t see electrical outlets, but I do see ethernet cable, depending on where in the ceiling it is. And so we might use the ethernet cables to provide what’s called power over ethernet. It doesn’t take much. Most access points need 15.

4 watts to be able to operate, same as a voice over IP phone. And today’s switches are designed to be able to give you that much power, at least out of every other ports. So you’ve got to consider that as well, because that might affect effect where you can or can’t place something. And then again, you got to ask questions like what type of encryption are we going to use? What type of aaa requirements are going to be? Because you just don’t want to turn on an access point, have it connected to your network, and then all of a sudden say, oh, it’s time for security. Because at that point you may already have people in your network.

11. WLAN Site Survey Interview Part10

Now wifi is getting more and more accepted through companies all the time. There was a point in history in my working with networks over the last 30 years, but especially since wifi came out in the last couple of decades, that companies would say, no, it’s not safe, I don’t want to use it. And I kept saying, oh, but it’s cool, you should use it. I didn’t want to say, they’re right, that it wasn’t secure, because back then it wasn’t secure, but nonetheless, it was cool stuff. Today we should realize that everybody wants wifi. And yes, there are problems if we don’t take the steps. And one great thing is to make sure you plan how it’s being used. If you need guest user access, I like using the wifi better than giving them a place to plug into the wall.

12. Documents and Reports Part1

Again, documentation about the facility. You just need to have that. This one’s a little picture is kind of cool. I can see the hallways, I can see the kind of furniture that might be in each of the offices. I see where the doors are. But I might ask things like what material are the walls and the doors made out of? All of this is important stuff. Is there kitchen area? So the blueprint, though, helps me. And here’s what happens with the vendors that I work with that have a wireless lan controller.

They have this software. You upload this blueprint into the wireless lan controller, and on that wireless lan controller, you’ll also put in the name and type of access point you bought and the type of antenna that it has. And when you list them all, quite literally, you can move your mouse over, click on one and drop it somewhere. And it’s going to create what they call a little heat map. It’s going to show you what the signal strength might be in some of the software. You could just say, here’s what I’ve got. And you might say, this area, let’s see, maybe I want it to be maximum coverage in this area, like a waiting room. I don’t care what happens in the conference room. And then this thing will just take all your devices and put them in different spots. And again, it’ll show you the overlap.

And again, it’s really cool seeing the heat maps because the redder it is, the more powerful it is. And it just gives you ideas of based on your diagram. And you can also put in things like the type of material the walls are made out of and the type of furniture. You can put all that in there. These programs are very sophisticated and it will show you where you could put them. In fact, it might even leave little question mark areas about having redundancy or where to put one in monitor mode to look for rogues. It’s just really cool. And as long as your picture is to scale, you pretty much have a good idea of where to put these access points.

13. Documents and Reports Part2

Now, the thing that those site surveys that cool little software can’t do for you is tell you about interference. So you may want to do a spectrum analysis so that you can walk around and report to that program where you found rf interference and how much that noise floor is going to be. Because that can help you define the boundaries of your access points and you can mark the those on the map.

So again we need to know so we have the right idea about hardware placement and configurations, the orientation of antennas and then which channels we want to use and all these really great things come out so you can do it right the very first time and get a good idea about what your throughput is going to be. And even though you do it according to the plan, you should still go back later and verify that you’re getting the coverage and the throughput that you wanted.

14. Documents and Reports Part3

Now, some of the cwna exam is focused on outdoor site surveys for doing bridge links. So when we’re doing those bridge links, I’m going to make it easy and tell you to understand some of the potential problems. The first is the Freynel zone, I think this Freynel zone. So the idea is I’ve got a tower, tall towers, maybe, spanning many, many miles. And there’s an effect about this radiated signal going back and forth to them that can be affected by having tall objects like trees or mountains or hills within a short distance, like within under 40% of the distance, total distance to one of the towers. They actually can cause some interference. Again, the earth bulge. If you give me a short six foot tower and you think about the curvature of the Earth at a six foot tower, you’re not going to have line of sight because the planets in the way.

So if I made a taller tower on both sides, I might barely make line of sight because they’re up higher. So we have to worry about that. Unless you’re part of the Flat Earth Society, then it shouldn’t have been a problem at all. Also, the free space path loss. Well, if we’re outdoors, more than likely we are using directional antennas. But guess what? Over distance, the signal still attenuates. And again, look at the link budget and the fade margin and that gets us back into the power that we’re going to use and anything else that’s going to cause a problem with outdoor reception.

15. Module 15 Review

So in this module, we talked about the wireless land site survey, the types of documents and reports that you may need or want to create, and how we might use different types of devices and antennas to be able to make a great wireless network both inside and outside.