Uncategorized

802.11ac Part7. Now, the 256 qam was a big upgrade, and that came with eight or 211 AC. It doesn’t mean everybody is using it or that they can use it. But, you know, we originally with a eight or 211 A, had the 64 qam, and that gave us this great 56 megabits per second for speed, you know, identified 64 unique different values. And if you broke it up into the little square with the each corner having the number of bits we can send, we were able…

Very High Throughput (VHT) Now in this module, we’re going to talk about what is now called very high throughput, which won’t be that in ten years from now, but anyway, it’s going to be the eight to eleven AC 2013 amendment. Now, this is a wifi that operates only at 5 ghz, but they can combine channels. Instead of having just 20 mhz, they can go 2040 8160. They change the way in which they do of the modulation to be able to send eight bits of data instead…

Wireless Attacks Part10 For whatever reason, we don’t hear a lot of people talk about denial of service. And you know what? Denial of service on radio frequency is the easiest thing you can do. I can go to any electronics store, buy a jammer, turn it on, and your wireless service is gone. It’s that easy. I mean, I want to keep people from getting out of the network. I can just, again, intentionally jam it. I could probably even do it with my laptop. If I get on…

Wireless Attacks Part5 Wireless land discovery is usually considered to be harmless. And why is that? Like my example of being in downtown Seattle, I wasn’t looking for a wireless network. I didn’t even think about getting into a wireless network. It just happened. My laptop back then with Windows, whatever, it was automatically connected to this wireless network and but people are doing that sometimes on purpose just to map where they are. And they called that war driving. Well, like I said, I wasn’t wardriving at that point,…

Types of Wireless Attacks We’re going to take a look at some of the different types of wireless attacks that could occur. So we’ll look at them from the point of view of somebody trying to break into the network, maybe somebody trying to steal your identity by tricking you. We’ll also look at ways in which our existing hardware can do some monitoring for intrusions and what we should probably create as far as an actual wireless security policy. Wireless Attacks Part1 So I mentioned this before when we…

Capacity vs. Coverage Part3 Another concept, especially when it comes to channels. At the 2. 4 ghz frequency we only have the three channels. In the United States, we have eleven channels at 5. So what we want to do is try to get through what they call a band steering. That means we want to try to move people, steer them from 2. 4 to 5 ghz where we have more advantages, more channels, more coverage, better speeds than the rest of it. And so if we can convince…

802.11 Coverage Considerations Part3 One of the recommended practices is that we don’t allow the access point to accept the slower speeds for connectivity. And that’s an important thing when we think about how to design your at least the 2. 4 ghz network. So by disabling those, you then don’t have this thing called the sticky client roaming problem. Sticky client look, here I am in the 1 minute megabit per second range and maybe there’s another access point over here that I’m closer to and I can get…

Troubleshooting So we’re going to talk about troubleshooting. And when we look at troubleshooting, we’re going to talk about all of the things that can cause issues with communications from a station to an access point. So look at things like what caused layer two retransmissions some of the coverage considerations, which, again, could be troubleshooting. Somebody says, hey, the wireless doesn’t work? Well, maybe it’s because there’s no coverage there. We’ll look at the differences between troubleshooting voice and data. We’re talking about things like performance and capacity, how…

Direct Sequence Spread Spectrum Part4 Now, after the data has been encoded using the chipping method, the transmitter is going to need to be able to modulate the signal to create the carrier signal that carries the chips. Now, we’re going to use something like differential binary phase shifting dbpsk to be able to use phases or at least two phase shifts. One that represents a zero chip and another that represents the one. Now, I hope you remember when we talked about phase shifting. That when we saw a…

Hopping Sequence So the hopping sequence that I was just talking about is very well published. And so that means they had a predefined hopping sequence. I mean, really, if you think about it, if I had some antenna that was transmitting on different channels, hopping from one to the other to a receiver. And remember back in the day when I was working with this, when it first at least arrived in my life, it was on the 900 MHz range, and it was about putting what they called…