Troubleshooting Wireless Signals – CompTIA Network+ N10-006 – 4.3

| May 8, 2015


The radio signals on your wireless network can be affected by many different external forces. In this video, you’ll learn how to troubleshoot wireless networks and understand more about signal loss, overlapping channels, signal to noise ratio, saturation, and firmware updates.
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When we think about wireless signals, we’re often thinking about an AM or FM radio in our car or even a satellite radio that we might be listening to. And a wireless network is very similar. It’s simply using frequencies in the 2.4 GHz and 5 GHz range.

And just as there can be interference and problems hearing your AM, FM, or satellite radio stations, there can be problems hearing what’s happening on your wireless network. It’s very susceptible to interference because it is wireless. This usually comes from sources outside of our network or even our control.

And very often, it is interference that we are making ourselves. There can also be conflicts between other wireless access points that might be using similar frequencies to ours. And of course, those are going to have conflicts and have difficulty communicating their wireless signals.

When we look at the things that can cause signal issues, interference is probably at the top of everyone’s list. This is something else that’s using our frequency. So it might be another access point that’s using our frequency. It might be a cordless phone or a microwave oven. But something is now conflicting with the frequencies that we are using for our wireless network.

We might also want to think about signal issues with signal strength. We may be far away from the access point. Or the signal that we’re sending from our device just isn’t putting up enough signal to reach the access point and communicate. And maybe the antennas that we’re using aren’t allowing us to communicate to an access point and back.

You might have the access point set to the incorrect channel. Some access points will try to find an open set of frequencies and automatically use those. But very often, you want to be able to manually set those. So you may want to look at the configuration of your access point and see if there are options to set exactly what frequencies you want to use for your access point.

You might also want to look at the environment around you. Different frequencies react differently. Some frequencies will pass through different objects, while others will bounce around off of objects. And if those bounced signals are reaching an access point all at different times, you could have problems receiving those signals on that antenna.

And it may be obvious, but you need to look at where you’re putting the access point. You may have put the access point in one place originally. But now your users may have moved away from that access point or are working in areas farther away than you expected. So you might want to rethink where you’re placing the access point. Because you’d like to have it as close to the users as possible.

It may be very easy to find the sources of interference for your wireless network just by looking around. You probably have fluorescent lights in your building. There might be a microwave oven that is occasionally used. Cordless telephones will use 2.4 GHz and 5 GHz ranges. And there might be high-power sources such as generators or other electrical equipment in the building that can conflict with your wireless networks.

Sometimes the source of the wireless interference is completely unpredictable. You might be in a building with many tenants. Every single tenant is going to have their own wireless network. And so you’re never quite sure what tenant might be using the same frequencies on their wireless network that you would like to use on yours.

There are a number of things in your operating system that you can use to start getting statistics and information about how well you’re receiving these wireless signals. You can run a netstat -e or use Performance Monitor to get a long-term view of how the performance has been on that wireless network over time.

Finding exactly the right frequencies to use can be a challenge. I used a wireless analyzer. And I was looking at my wireless network. You can see there is someone on channel 6 and someone on channel 11 on these 2.4 GHz ranges.

And there’s no overlap between these two. Everybody has their own frequency space. But if somebody was to show up and start using channel 8, for instance, it would overlap both channel 6 and channel 11. And you can see now that one person is now sending a lot of signal strength over a series of frequencies that will affect multiple access points.

An important metric to look at on your wireless network is the signal to noise ratio. You can see in this diagram that all of the solid lines are the signal strength of the wireless network. And down here is a set of noise for the wireless network.

There will always be some noise going across these frequencies. Your goal is to have the noise as low as possible and the signal strength as high as possible so that you can have the widest range of this ratio.

One of the challenges you have with wireless networks is that anyone can connect to the shared wireless medium and use it. If you have too many devices on the network, you may find that overall performance is suffering because of this. This is device saturation.

Bandwidth saturation would be when perhaps only one device is on the network, but they’re doing very large data transfers and using all of the bandwidth and wireless availability on the network. You’ll commonly see this in places where there are a lot of people, like a conference or an airport or a hotel. And when you have that many people in one single place, you can easily overwhelm a wireless access point.

We spoke in a previous video about other updates and having to perform firmware upgrades. But this is something you also have to consider on your wireless network. Upgrading the firmware of a wireless access point or a wireless device on your computer can occasionally occur.

They don’t happen very often. But when they do, you may want to consider whether you want to update that firmware or not. It can have dramatic changes over the performance of the wireless network. It might improve performance dramatically. Or it might decrease performance dramatically. I have had these occur in both directions when performing wireless firmware upgrades.

You also have to check and make sure that all of your devices will still be compatible with this upgrade. Different chipsets work in different ways. So it may be worthwhile to test the upgrade, have it run for a little while. And if that works, you can then roll it out to all of your access points.

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Category: CompTIA Network+ N10-006

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