I swear I'll get back to blogging about low level network communication someday... today is not that day.
I just had to wrestle with my tablet, a Samsung Galaxy Tab 10.1 to connect to a 5Ghz wifi AP. I found the problem, even after googling, people seem to just give up... hopefully people having trouble, will find this. (for those looking for help, scroll down to the marker and start reading, a little backstory follows)
I have a pretty complicated network, as you might imagine; being that my wifi is mainly shared, I actually setup an Access Point that will automatically choose the "least congested" channel, so that my android devices can connect to it. Mainly my phone, since it will only connect to 2.4Ghz wireless. I do however, have 5Ghz routers, and one is on the network, and it's the only 5Ghz in my neighborhood (that I've ever detected). This is good because there's typically so many 2.4 Ghz networks that congestion will stop you from having a nice, clear, quality signal; as I've stated in previous posts, this will slow down your network communication to a crawl.
Well, that's exactly what happened for me today, I have one AP at 2.4Ghz auto-select "least congested" JUST FOR ME, and a household, shared AP, also 2.4Ghz, that I tend to avoid; primarily so that the bandwidth there can be used by others in the house, and I don't have to fight with their devices... in terms of contention. so there's that. But today, while using my tablet, I found that I was on the household AP, and trying to watch youtube clips was insanely slow (5+ mins of buffering for a 2 minute video). I said enough is enough, and went to check my network status; once I found I was on the household wifi I thought to myself "that must be why" and promptly switched to my "least congested" access point. To my disappointment, this yielded zero improvement. Without going through the motions of reassigning the wifi channels to all my devices to see if I can find something a little less congested (a very difficult feat in this environment); I decided to jump-ship and onto the 5Ghz. I set my tablet to only connect to 5Ghz networks.... voila. wait what? no networks? how is this right?
I logged into my 5Ghz AP and started tinkering.
---- FIX FOLLOWS (for those skipping my little story time) ----
After a little effort, I changed the settings to be more compatible, and the network popped up almost immediately. My current 5Ghz settings (that are working with my Tab): I selected a low-numbered channel, the second lowest, 36 I believe, changed the channel width to 20Mhz, and saved.
That's it. pretty much just pick a channel in the first dozen or so.
network popped up quickly, I connected and all my wifi woes went away.
Happy networking folks!
Showing posts with label wifi. Show all posts
Showing posts with label wifi. Show all posts
Friday, June 28, 2013
Sunday, April 21, 2013
WiFi? or not to WiFi?
I feel as though I should really type this out once; and give everyone a good rundown of HOW wifi works, what should be changed, and what should not be changed. So here goes.
DISCLAIMER: This is for a fairly intermediate crowd, those who have setup wifi before, understand that wifi has channels, SSIDs, etc. - to those in the industry, that will be considered a beginner level. I'll try to explain things clearly.
First of all, let's talk about frequency. It's getting so confusing when picking a router, do I get "gigabit" or "Wireless N" or that fancy "Wireless AC" (whatever that is)... what do I need, and why? - I'm here to help with exactly that, and more.
There are two parts when it comes to frequency. First, is the capability of the router (or AP) - is it a "dual band", or "simultaneous dual band"? what's the difference and why does it matter? Well, with most older, common 'wireless' networks for households, you didn't have a choice of 'band' - everything operated on 2.4Ghz. Just like your radio, where stations operate at frequencies like "104.5 FM" (which is 104.5Mhz) - same applies to wireless, just instead of transmitting voice, it's data. 2.4Ghz is by-far the most common. It's internationally a 'free' channel. Which means, you don't need a permit to broadcast on the channel, anyone can use it, at any time, for any reason. This is why you'll see wireless phones toting "2.4Ghz" on the box, etc. This 'band' is the only frequency range available for the 802.11b/g (more affectionately known as 'wireless b' and 'wireless g'). In being so, earlier model routers, and inexpensive options will default to this range and this range alone; not having the necessary transceivers to operate anywhere but on the 2.4Ghz spectrum. "Dual band" comes from routers being able to operate not only on the 2.4Ghz band, but the 5Ghz band aswell. The 5Ghz band typically ranges from 5.180Ghz to 5.825Ghz, which is much more broad than the 2.4Ghz band (spanning 2.412Ghz to 2.472Ghz); the benefits of this is quite simple, more room for more networks; this leads us into our second point, then we'll have a small discussion on which is better in what situations.
The second part of frequency has to do with contention; contention is a fancy term to talk about interference - specifically the interference created by OTHER networks operating on the same, or similar frequencies. I've already mentioned that each 'band' is a span of frequencies; what I haven't said is that each of those frequencies boils down to 20Mhz segments. Let me start with an analogy. Think for a moment about our earlier discussion of radio. When you're in your car, as I'm sure you're familliar, if you tune away, just one step from a local radio station (one that comes in quite clearly) often, you can hear the station, both one-step above and below the actual 'channel' - this is because of BANDWIDTH. the station is CENTERED on the frequency you're tuned into - our earlier example was 104.5Mhz; this is the channel center. From there, the station occupies an amount of frequency range both above and below the 104.5Mhz mark, the further you get away from the station, the lower the effect of this, so it won't happen on all stations. You'll notice that at 104.3 and 104.7 (the next step in either direction), you can still hear the original station, though the transmission may be poor, it's there. Same thing with wifi, except the channels are 5Mhz apart, and the bandwidth is 20mhz - this means that there are a LOT of overlaps when it comes to 2.4Ghz. so much so, that in north america, there are only 3 viable "non overlapping" channels: 1, 6, and 11. Obviously on 5Ghz, there are many more channels, and while they overlap with other channels just as much, there are so many of them, there's a large portion more "non-overlapping channels".
So what does this all mean? how does it affect your decision on a router? well, quite simply put, depending on where you live and what you need, you may want to pick 5ghz, or you may require 2.4ghz. According to the scientific properties of electromagnetic waves, the lower the wavelength, the less likely it is to be scattered and/or misdirected - this means if you need high penetration, or longer distance, 2.4Ghz is likely for you. how long? about 75m (240 ft). you can attain longer links with directional antennas (eg parabolics . If you need shorter-range with more reliable access in a high-density environment (eg, a housing complex or apartment building), 5ghz is definitely the way to go.
Word of warning while choosing a frequency range - many small devices (such as smartphones and tablets) don't necessarily support dual-band. it would be worthwhile to look into this while picking an option. That said, if you're in a high-density environment, but need both high reliability and 2.4ghz for micro devices, a simultaneous dual band option would be best, as it will do both 2.4ghz and 5ghz at the same time.
Next, let's talk network names and encryption.
If you've ever setup a wireless network, you've dealt with these before. The key with network naming is to pick something unique for you, that you don't mind having other people see, that you will recognize as yours. I've seen people even put witty phrases as their network names. be creative; the sky is the limit here. Next, you'll have to consider encryption. DO NOT, and I really mean this, DO NOT USE WEP - if anyone tells you to use it, hit them for me. ALWAYS use WPA. WPA2 if possible. Don't complicate the wireless too much, if you're going to use a WPA/WPA2 mixed (or WPA2 Auto) set encryption to auto as well. for just WPA, use TKIP, for just WPA2, use AES. I cannot recommend highly enough to use WPA2 with AES. This is an industry standard (802.11i for those curious), and is the recommended configuration from apple, the wifi alliance and IEEE for wireless encryption. It is the newest and possibly the best wireless encryption standard to date and has yet to be broken. WITH THAT SAID, pick a good wireless encryption key sequence; the only known attacks on WPA2/AES to date, have to do with guessing passwords. Do not just use character substitution in a short word for the password. Eg: 'P@ssW0rD' is no more secure than 'Password' - use something long, and easy to remember. In the past I've used slogans and parts of mission statements, or peoples combined middle names (eg, the middle names of all the people that regularly use the wireless, with spaces inbetween) - ensure it's not something you'll hesitate to give out to guests who need wireless, but ensure it's not something someone who doesn't know you, will readily guess, or be able to pull from a dictionary. Even using a line from a song that the whole family enjoys, is more secure than a single word; whether that word has numbers and symbols in it or not.
I cannot emphasize strongly enough to use a strong wireless password. take some time and do it right, you'll never have to worry about it again.
Next, we're going to get into some more complicated stuff. You'll find most of these options in your "Advanced" section. I won't tell you which ones to pick to turn on or off, you'll have to decide on that from my description of what they do; no two networks are built for doing the same thing, and no two networks are designed for the same users; be careful when changing these options as they can also have adverse effects on performance - however, DO EXPERIMENT - the worst that can happen is needing to reset the router to defaults (a procedure you should look up first) and re-configuring it from scratch to get reconnected. Enjoy.
BEACON INTERVAL: This setting changes how frequently the Beacon is sent. The Beacon has two main tasks: 1. to inform stations that the access point is still active, and 2. to deliver 'wake up' messages to stations in 'low power' states. I'll deal with point #2 more in my next talking point "DTIM Interval". Basically, the beacon contains information about the network, the network name, it's wireless encryption types (only types, not the keys), etc. effectively everything required for a new station to connect. Higher Beacon intervals: less intrusive. the Beacon has a fairly high priority for transmission, as it not only provides information for new stations to connect it tells existing connections that it's still around, if the Beacon is set too low, the router or AP will spend all it's time and available bandwidth advertising that it's there, and spend no time actually moving information. Too low of a beacon interval, and connected stations may lose their connection at random. The beacon is typically measured in ms, and the default is typically 100ms (1/10th of a second), I've seen these as low as 250ms (1/4 of a second) or as frequently as 50ms. Depending on your needs, you may want to increase this number, if it creates a problem of dropped connections you may want to decrease the number.
DTIM Interval: DTIM's are wake-up messages for 'sleeping' devices. effectively it boils down to; if a small device is in a standby state or has activated a low-power state on the device will only power-up for two reasons: 1. to send information. 2. a DTIM request. Basically, the DTIM is telling the low-power devices, to connect to the AP, since it has a message for it. the device will 'wake' from it's low-power mode, connect to the AP and request the delayed transaction message. In low-power states, the device will only listen for beacons, nothing more. DTIM is set in frequency of beacon intervals; so a setting of 1, is every beacon, 2, is every other beacon. etc. Typically DTIM is set to 1 or 2, but can be set higher if you wish. KEEP IN MIND, this is also based on the beacons interval, if you have a higher interval, you may want to consider a lower DTIM, a higher beacon, you may want to consider a lower DTIM. I don't believe there are any adverse effects to a higher DTIM, except that low-power devices (such as cellphones and tablets) will take seconds longer to receive a message while in standby; this may not be important to you.
PREAMBLE: options are long and short. Long preambles are required for older equipment, and are more standards compliant. however, there are many performance improvements to a short preamble. Effectively, the preamble is a sync message prior to transmission, it's sent by the transmitting station (eg. your PC or the router), so that receiving stations can sync their clock rate to the transmission. newer hardware requires less preamble to sync. cheap hardware may also require a longer preamble. There is no significant change in router performance either way, short is better, but only slightly. If possible use short, if any device exhibits strange connection behavior, try a long preamble to try to correct the problem.
PROTECTED MODE: This is kind of a big topic, so try to hold on. Effectively Protected mode has two parts: 1. a "basic" rate, and 2. a request, then send, method of communication. Let me break this down a little. The basic rate is the MINIMUM require connection speed that a station must sustain to be able to participate in the network. Typical values are 1 or 2Mbps. This is low because, typically, you want a lot of compatibility. If you're on a computer with wireless, you can check your connection rate at any time, typically by opening your wireless connection status window; it will show the connection "speed" - if that speed is less than the basic rate of the network, your connection is not considered valid. The reason this is important is because of the second point. The basic rate is used for control messages for RTS/CTS (Request to Send, Clear to Send) requests. Protected mode, if set to auto, is triggered when the network detects that some stations cannot 'hear' other stations, and/or collisions (more than one station sending at a time) happens frequently. How this works is as follows. Your PC (let's just say, it works in reverse too) will transmit a RTS to the AP. That request contains all the information about the length of the transmission you want to send, etc. the AP will then transmit a CTS, which includes all the information from the request, plus a confirmation that you're clear to send. The AP does this so that every station on the network knows that someone is transmitting for X ms (whatever was defined in the RTS). All other stations will now wait (or "back off") for AT LEAST that length of time, before attempting to request to send. This is analogous to raising your hand to speak in a classroom. While just blurting out answers is faster, if everyone did that, you would not be able to understand anyone. This, while slowing down the overall transaction time for each message sent, ensures that only one "person" (or station) 'speaks' at a time. This ensures more reliable communication across the network, but can slow it down significantly. If you're in a situation where you have a lot of differing devices with differing capabilities, you may want to consider turning this on. If you're in a situation where you need faster speed of message transaction, you may want to turn this off. cases and results will vary.
Wireless Multimedia (WMM): Also known as WME (Wireless Multimedia Extensions) is an extension of the RTS/CTS found in protected mode. Effectively, what happens is an RTS/CTS request/response occurs, whether or not Protected mode is enabled, however, the main difference here is, rather than sending just one message, the station is requesting time to send a block of messages. - this VASTLY improves overall throughput for the one connection stream, however it greatly delays other transmissions. choose this option carefully. I highly recommend using an Ethernet connection for anything multimedia; but if you must use wireless to connect a media extender, be sure to enable this; I will leave you with a warning, if anyone is doing anything time-sensitive on the network (VoIP or Gaming), and this option is set to ON, they WILL NOTICE a significant drop in responsiveness in their data. For gamers, this phenomenon is referred to as "lag". Reduce LAG by turning off WMM.
There you have it. The comprehensive 'advanced wireless configuration for dummies' guide. I hope this helps some people in choosing the right wireless access points and network configurations. I don't think this is the first time I've posted this. In any case, have a great day, and may all your packets arrive with their checksums intact.
DISCLAIMER: This is for a fairly intermediate crowd, those who have setup wifi before, understand that wifi has channels, SSIDs, etc. - to those in the industry, that will be considered a beginner level. I'll try to explain things clearly.
First of all, let's talk about frequency. It's getting so confusing when picking a router, do I get "gigabit" or "Wireless N" or that fancy "Wireless AC" (whatever that is)... what do I need, and why? - I'm here to help with exactly that, and more.
There are two parts when it comes to frequency. First, is the capability of the router (or AP) - is it a "dual band", or "simultaneous dual band"? what's the difference and why does it matter? Well, with most older, common 'wireless' networks for households, you didn't have a choice of 'band' - everything operated on 2.4Ghz. Just like your radio, where stations operate at frequencies like "104.5 FM" (which is 104.5Mhz) - same applies to wireless, just instead of transmitting voice, it's data. 2.4Ghz is by-far the most common. It's internationally a 'free' channel. Which means, you don't need a permit to broadcast on the channel, anyone can use it, at any time, for any reason. This is why you'll see wireless phones toting "2.4Ghz" on the box, etc. This 'band' is the only frequency range available for the 802.11b/g (more affectionately known as 'wireless b' and 'wireless g'). In being so, earlier model routers, and inexpensive options will default to this range and this range alone; not having the necessary transceivers to operate anywhere but on the 2.4Ghz spectrum. "Dual band" comes from routers being able to operate not only on the 2.4Ghz band, but the 5Ghz band aswell. The 5Ghz band typically ranges from 5.180Ghz to 5.825Ghz, which is much more broad than the 2.4Ghz band (spanning 2.412Ghz to 2.472Ghz); the benefits of this is quite simple, more room for more networks; this leads us into our second point, then we'll have a small discussion on which is better in what situations.
The second part of frequency has to do with contention; contention is a fancy term to talk about interference - specifically the interference created by OTHER networks operating on the same, or similar frequencies. I've already mentioned that each 'band' is a span of frequencies; what I haven't said is that each of those frequencies boils down to 20Mhz segments. Let me start with an analogy. Think for a moment about our earlier discussion of radio. When you're in your car, as I'm sure you're familliar, if you tune away, just one step from a local radio station (one that comes in quite clearly) often, you can hear the station, both one-step above and below the actual 'channel' - this is because of BANDWIDTH. the station is CENTERED on the frequency you're tuned into - our earlier example was 104.5Mhz; this is the channel center. From there, the station occupies an amount of frequency range both above and below the 104.5Mhz mark, the further you get away from the station, the lower the effect of this, so it won't happen on all stations. You'll notice that at 104.3 and 104.7 (the next step in either direction), you can still hear the original station, though the transmission may be poor, it's there. Same thing with wifi, except the channels are 5Mhz apart, and the bandwidth is 20mhz - this means that there are a LOT of overlaps when it comes to 2.4Ghz. so much so, that in north america, there are only 3 viable "non overlapping" channels: 1, 6, and 11. Obviously on 5Ghz, there are many more channels, and while they overlap with other channels just as much, there are so many of them, there's a large portion more "non-overlapping channels".
So what does this all mean? how does it affect your decision on a router? well, quite simply put, depending on where you live and what you need, you may want to pick 5ghz, or you may require 2.4ghz. According to the scientific properties of electromagnetic waves, the lower the wavelength, the less likely it is to be scattered and/or misdirected - this means if you need high penetration, or longer distance, 2.4Ghz is likely for you. how long? about 75m (240 ft). you can attain longer links with directional antennas (eg parabolics . If you need shorter-range with more reliable access in a high-density environment (eg, a housing complex or apartment building), 5ghz is definitely the way to go.
Word of warning while choosing a frequency range - many small devices (such as smartphones and tablets) don't necessarily support dual-band. it would be worthwhile to look into this while picking an option. That said, if you're in a high-density environment, but need both high reliability and 2.4ghz for micro devices, a simultaneous dual band option would be best, as it will do both 2.4ghz and 5ghz at the same time.
Next, let's talk network names and encryption.
If you've ever setup a wireless network, you've dealt with these before. The key with network naming is to pick something unique for you, that you don't mind having other people see, that you will recognize as yours. I've seen people even put witty phrases as their network names. be creative; the sky is the limit here. Next, you'll have to consider encryption. DO NOT, and I really mean this, DO NOT USE WEP - if anyone tells you to use it, hit them for me. ALWAYS use WPA. WPA2 if possible. Don't complicate the wireless too much, if you're going to use a WPA/WPA2 mixed (or WPA2 Auto) set encryption to auto as well. for just WPA, use TKIP, for just WPA2, use AES. I cannot recommend highly enough to use WPA2 with AES. This is an industry standard (802.11i for those curious), and is the recommended configuration from apple, the wifi alliance and IEEE for wireless encryption. It is the newest and possibly the best wireless encryption standard to date and has yet to be broken. WITH THAT SAID, pick a good wireless encryption key sequence; the only known attacks on WPA2/AES to date, have to do with guessing passwords. Do not just use character substitution in a short word for the password. Eg: 'P@ssW0rD' is no more secure than 'Password' - use something long, and easy to remember. In the past I've used slogans and parts of mission statements, or peoples combined middle names (eg, the middle names of all the people that regularly use the wireless, with spaces inbetween) - ensure it's not something you'll hesitate to give out to guests who need wireless, but ensure it's not something someone who doesn't know you, will readily guess, or be able to pull from a dictionary. Even using a line from a song that the whole family enjoys, is more secure than a single word; whether that word has numbers and symbols in it or not.
I cannot emphasize strongly enough to use a strong wireless password. take some time and do it right, you'll never have to worry about it again.
Next, we're going to get into some more complicated stuff. You'll find most of these options in your "Advanced" section. I won't tell you which ones to pick to turn on or off, you'll have to decide on that from my description of what they do; no two networks are built for doing the same thing, and no two networks are designed for the same users; be careful when changing these options as they can also have adverse effects on performance - however, DO EXPERIMENT - the worst that can happen is needing to reset the router to defaults (a procedure you should look up first) and re-configuring it from scratch to get reconnected. Enjoy.
BEACON INTERVAL: This setting changes how frequently the Beacon is sent. The Beacon has two main tasks: 1. to inform stations that the access point is still active, and 2. to deliver 'wake up' messages to stations in 'low power' states. I'll deal with point #2 more in my next talking point "DTIM Interval". Basically, the beacon contains information about the network, the network name, it's wireless encryption types (only types, not the keys), etc. effectively everything required for a new station to connect. Higher Beacon intervals: less intrusive. the Beacon has a fairly high priority for transmission, as it not only provides information for new stations to connect it tells existing connections that it's still around, if the Beacon is set too low, the router or AP will spend all it's time and available bandwidth advertising that it's there, and spend no time actually moving information. Too low of a beacon interval, and connected stations may lose their connection at random. The beacon is typically measured in ms, and the default is typically 100ms (1/10th of a second), I've seen these as low as 250ms (1/4 of a second) or as frequently as 50ms. Depending on your needs, you may want to increase this number, if it creates a problem of dropped connections you may want to decrease the number.
DTIM Interval: DTIM's are wake-up messages for 'sleeping' devices. effectively it boils down to; if a small device is in a standby state or has activated a low-power state on the device will only power-up for two reasons: 1. to send information. 2. a DTIM request. Basically, the DTIM is telling the low-power devices, to connect to the AP, since it has a message for it. the device will 'wake' from it's low-power mode, connect to the AP and request the delayed transaction message. In low-power states, the device will only listen for beacons, nothing more. DTIM is set in frequency of beacon intervals; so a setting of 1, is every beacon, 2, is every other beacon. etc. Typically DTIM is set to 1 or 2, but can be set higher if you wish. KEEP IN MIND, this is also based on the beacons interval, if you have a higher interval, you may want to consider a lower DTIM, a higher beacon, you may want to consider a lower DTIM. I don't believe there are any adverse effects to a higher DTIM, except that low-power devices (such as cellphones and tablets) will take seconds longer to receive a message while in standby; this may not be important to you.
PREAMBLE: options are long and short. Long preambles are required for older equipment, and are more standards compliant. however, there are many performance improvements to a short preamble. Effectively, the preamble is a sync message prior to transmission, it's sent by the transmitting station (eg. your PC or the router), so that receiving stations can sync their clock rate to the transmission. newer hardware requires less preamble to sync. cheap hardware may also require a longer preamble. There is no significant change in router performance either way, short is better, but only slightly. If possible use short, if any device exhibits strange connection behavior, try a long preamble to try to correct the problem.
PROTECTED MODE: This is kind of a big topic, so try to hold on. Effectively Protected mode has two parts: 1. a "basic" rate, and 2. a request, then send, method of communication. Let me break this down a little. The basic rate is the MINIMUM require connection speed that a station must sustain to be able to participate in the network. Typical values are 1 or 2Mbps. This is low because, typically, you want a lot of compatibility. If you're on a computer with wireless, you can check your connection rate at any time, typically by opening your wireless connection status window; it will show the connection "speed" - if that speed is less than the basic rate of the network, your connection is not considered valid. The reason this is important is because of the second point. The basic rate is used for control messages for RTS/CTS (Request to Send, Clear to Send) requests. Protected mode, if set to auto, is triggered when the network detects that some stations cannot 'hear' other stations, and/or collisions (more than one station sending at a time) happens frequently. How this works is as follows. Your PC (let's just say, it works in reverse too) will transmit a RTS to the AP. That request contains all the information about the length of the transmission you want to send, etc. the AP will then transmit a CTS, which includes all the information from the request, plus a confirmation that you're clear to send. The AP does this so that every station on the network knows that someone is transmitting for X ms (whatever was defined in the RTS). All other stations will now wait (or "back off") for AT LEAST that length of time, before attempting to request to send. This is analogous to raising your hand to speak in a classroom. While just blurting out answers is faster, if everyone did that, you would not be able to understand anyone. This, while slowing down the overall transaction time for each message sent, ensures that only one "person" (or station) 'speaks' at a time. This ensures more reliable communication across the network, but can slow it down significantly. If you're in a situation where you have a lot of differing devices with differing capabilities, you may want to consider turning this on. If you're in a situation where you need faster speed of message transaction, you may want to turn this off. cases and results will vary.
Wireless Multimedia (WMM): Also known as WME (Wireless Multimedia Extensions) is an extension of the RTS/CTS found in protected mode. Effectively, what happens is an RTS/CTS request/response occurs, whether or not Protected mode is enabled, however, the main difference here is, rather than sending just one message, the station is requesting time to send a block of messages. - this VASTLY improves overall throughput for the one connection stream, however it greatly delays other transmissions. choose this option carefully. I highly recommend using an Ethernet connection for anything multimedia; but if you must use wireless to connect a media extender, be sure to enable this; I will leave you with a warning, if anyone is doing anything time-sensitive on the network (VoIP or Gaming), and this option is set to ON, they WILL NOTICE a significant drop in responsiveness in their data. For gamers, this phenomenon is referred to as "lag". Reduce LAG by turning off WMM.
There you have it. The comprehensive 'advanced wireless configuration for dummies' guide. I hope this helps some people in choosing the right wireless access points and network configurations. I don't think this is the first time I've posted this. In any case, have a great day, and may all your packets arrive with their checksums intact.
Saturday, January 5, 2013
Understanding Bandwidth
Hello again everybody!
I felt it was about time to dust off the blog and give it a go. I think I should start a series on the essentials of networking and what you should know about it, to make an informed decision about what to buy, etc.
This could get very technical, so try to follow along as I take you through all this.
How do I know this: Years in college and hands-on experience working I.T. in my local area. I've seen the effects of everything I'll be discussing.
When deciding on a network type, you really have to start with, what will I be doing with the network. For many, the answer is easy, I want to get on the internet; for others, the answer is a bit more complicated.
When talking about speed, it's important to note that there are two major measurements of indicating speed, they're closely related but give very different numbers. Think about it like temperature, Celsius and Fahrenheit, if the temperature goes up, both will rise, if it goes down, they both will fall, but not necessarily at the same speed, or to the same numbers, or by the same amounts.
These two are in bits per second (bps) and Bytes per second (Bps)
Confused yet? you should be.
The way this works is that a bit is a single 1 or 0 in a computer system; a byte is a set of 8 bits that contains information, one value of a possible 255. Why the strange numbers? because a bit has two options, either be a 1, or a 0. which means that if you want 3 options, you need to use two bits, but two bits gives you 4 options, one of which is simply invalid. but what if you want 5 options? you need 3 bits, but three bits means you have 8 options (000, 001, 010, 011, 100, 101, 110, 111), 3 of which will simply be invalid. It's because of this (factoring by 2), which is why we see the same numbers cropping up with computers a lot.
2, 4, 8, 16, 32, 64, 128...
so what happens when bps meets Bps?
well, the speed in bps, is much higher in number than the speed in Bps.
For simplicity, lets use a value very close to the national average, that divides nicely, so it's easy to follow: 16. a majority of internet connections in north america are running at aproximately 16 megabits per second. that means, at any given second, 16,000,000 bits can travel across your internet link. sound like a lot? it used to be.
Truth is, 16,000,000 bits is only 2MB (megabytes in this case)
I want to point something out before moving further. the difference between bits and bytes is supposed to be indicated by the use of capital or lower case lettering. eg. 16 megabits per second is supposed to be indicated with 16 mbps (with a capital on the M being optional), and 16 megabytes per second is supposed to be indicated with 16 mBps (again, capital on the M is optional). the capital "B" indicates bytes, where the lower-case "b" indicates bits. Unfortunately, not everyone (especially marketing departments) understand this; so we get ISPs selling 16MBPS speeds, which is actually in bits.
so, with an average connection speed of 16mbps, that means we get 2MBps (16/8, because there's 8 bits per byte)
This trend of using bits per second, penetrates the telecom world. whenever dealing with communication speeds between two points, whether they are connected by ethernet, wireless, fiber optics, or a string with two cans, generally, we use bits per second. The problem with this, of course, is that everyone else uses bytes per second.
Example: in windows, all file transfer dialogs are in bytes per second, not bits. This means if you have a 16mbps line to the internet and download something, windows will show your speed (given that you're using the entire thing for just this download) as 2MBps. This has caused (in the past) a lot of confusion about what actual speed consumers are getting and what they should expect to get.
one of the most common misconceptions I've seen with internet is "I pay for 10mb service, but I can only download at 1.2mbps" - that's about what you should expect from 10mb service...
Bandwidth is a crazy thing too, since we have USB 2.0 which, in theory, runs at 480mbps, and the fastest I've seen it transfer has been about 200mbps (aproximately 25MBps) - what they don't tell you is that some of these connection types require overhead, USB more than most. Ethernet is actually rather slim on it's overhead, running about 40 bytes of overhead per packet (1500bytes or so): about 2.5% overhead. obviously it's much higher with USB.
So how much bandwidth do you need? depends on what you're doing. For an example, let's talk about HD video. If, by chance, you wanted to stream full-frame HD video from a blu-ray disk to a computer across a network, you would need to be able to sustain a minimum transfer speed, which is the same or greater than the amount of data per second in the blu-ray video files. Luckily, the specifications for these formats are published: first some facts from the specs.
BluRay disks when playing video, have a defined maximum bitrate of 54mbit/s - so, for example, if you wanted to send the bluray to a media player on wireless, you're going to have a bad time, depending on the wifi.
I say that because of duplexing. Full-Duplex is when you have a dedicated line of communication to/from a source, Half-Duplex is when you have to share a send/receive channel. Think of this like trying to shout over someone: nobody can understand either of you, so one person can talk at a time - this is half-duplex. If you have a direct line to someone's ear, and they have a direct line to yours, you and they can both talk, hearing only the other's voice, which makes more sense.
okay, so the example broke down at the end, give me a break. :)
so wireless, by nature (since you're only using one channel) is half-duplex, meaning the theoretical 54mbps on Wireless G (802.11g) is shared amongst send and receive, which would be fine, if you didn't have to send confirmations that you received information, and requests for more. This means your real-bandwidth on wireless will be significantly less than the 54mbps as advertised. This is the reason behind Wireless N being recommended for 'streaming' media.
wired networking could definitely handle it, transferring, on average, 100mbps in full-duplex mode. This far out performs the 54mbps coming off the blu-ray, and stutter-free playback should be possible... provided the rest of the network is fairly quiet.
Bandwidth is a topic that seems to confuse many people, here I'm talking about bandwidth in your house, and I hope that clears things up for you and yours. Soon I'll have discussions more in-depth about why wireless bandwidth isn't nearly what it should be, moreso than just being half-duplex. why we don't have full-duplex wireless, as well as internet bandwidth (why so slow). All this among many other topics to help clarify your digital life.
Be safe, enjoy.
I felt it was about time to dust off the blog and give it a go. I think I should start a series on the essentials of networking and what you should know about it, to make an informed decision about what to buy, etc.
This could get very technical, so try to follow along as I take you through all this.
How do I know this: Years in college and hands-on experience working I.T. in my local area. I've seen the effects of everything I'll be discussing.
When deciding on a network type, you really have to start with, what will I be doing with the network. For many, the answer is easy, I want to get on the internet; for others, the answer is a bit more complicated.
When talking about speed, it's important to note that there are two major measurements of indicating speed, they're closely related but give very different numbers. Think about it like temperature, Celsius and Fahrenheit, if the temperature goes up, both will rise, if it goes down, they both will fall, but not necessarily at the same speed, or to the same numbers, or by the same amounts.
These two are in bits per second (bps) and Bytes per second (Bps)
Confused yet? you should be.
The way this works is that a bit is a single 1 or 0 in a computer system; a byte is a set of 8 bits that contains information, one value of a possible 255. Why the strange numbers? because a bit has two options, either be a 1, or a 0. which means that if you want 3 options, you need to use two bits, but two bits gives you 4 options, one of which is simply invalid. but what if you want 5 options? you need 3 bits, but three bits means you have 8 options (000, 001, 010, 011, 100, 101, 110, 111), 3 of which will simply be invalid. It's because of this (factoring by 2), which is why we see the same numbers cropping up with computers a lot.
2, 4, 8, 16, 32, 64, 128...
so what happens when bps meets Bps?
well, the speed in bps, is much higher in number than the speed in Bps.
For simplicity, lets use a value very close to the national average, that divides nicely, so it's easy to follow: 16. a majority of internet connections in north america are running at aproximately 16 megabits per second. that means, at any given second, 16,000,000 bits can travel across your internet link. sound like a lot? it used to be.
Truth is, 16,000,000 bits is only 2MB (megabytes in this case)
I want to point something out before moving further. the difference between bits and bytes is supposed to be indicated by the use of capital or lower case lettering. eg. 16 megabits per second is supposed to be indicated with 16 mbps (with a capital on the M being optional), and 16 megabytes per second is supposed to be indicated with 16 mBps (again, capital on the M is optional). the capital "B" indicates bytes, where the lower-case "b" indicates bits. Unfortunately, not everyone (especially marketing departments) understand this; so we get ISPs selling 16MBPS speeds, which is actually in bits.
so, with an average connection speed of 16mbps, that means we get 2MBps (16/8, because there's 8 bits per byte)
This trend of using bits per second, penetrates the telecom world. whenever dealing with communication speeds between two points, whether they are connected by ethernet, wireless, fiber optics, or a string with two cans, generally, we use bits per second. The problem with this, of course, is that everyone else uses bytes per second.
Example: in windows, all file transfer dialogs are in bytes per second, not bits. This means if you have a 16mbps line to the internet and download something, windows will show your speed (given that you're using the entire thing for just this download) as 2MBps. This has caused (in the past) a lot of confusion about what actual speed consumers are getting and what they should expect to get.
one of the most common misconceptions I've seen with internet is "I pay for 10mb service, but I can only download at 1.2mbps" - that's about what you should expect from 10mb service...
Bandwidth is a crazy thing too, since we have USB 2.0 which, in theory, runs at 480mbps, and the fastest I've seen it transfer has been about 200mbps (aproximately 25MBps) - what they don't tell you is that some of these connection types require overhead, USB more than most. Ethernet is actually rather slim on it's overhead, running about 40 bytes of overhead per packet (1500bytes or so): about 2.5% overhead. obviously it's much higher with USB.
So how much bandwidth do you need? depends on what you're doing. For an example, let's talk about HD video. If, by chance, you wanted to stream full-frame HD video from a blu-ray disk to a computer across a network, you would need to be able to sustain a minimum transfer speed, which is the same or greater than the amount of data per second in the blu-ray video files. Luckily, the specifications for these formats are published: first some facts from the specs.
BluRay disks when playing video, have a defined maximum bitrate of 54mbit/s - so, for example, if you wanted to send the bluray to a media player on wireless, you're going to have a bad time, depending on the wifi.
I say that because of duplexing. Full-Duplex is when you have a dedicated line of communication to/from a source, Half-Duplex is when you have to share a send/receive channel. Think of this like trying to shout over someone: nobody can understand either of you, so one person can talk at a time - this is half-duplex. If you have a direct line to someone's ear, and they have a direct line to yours, you and they can both talk, hearing only the other's voice, which makes more sense.
okay, so the example broke down at the end, give me a break. :)
so wireless, by nature (since you're only using one channel) is half-duplex, meaning the theoretical 54mbps on Wireless G (802.11g) is shared amongst send and receive, which would be fine, if you didn't have to send confirmations that you received information, and requests for more. This means your real-bandwidth on wireless will be significantly less than the 54mbps as advertised. This is the reason behind Wireless N being recommended for 'streaming' media.
wired networking could definitely handle it, transferring, on average, 100mbps in full-duplex mode. This far out performs the 54mbps coming off the blu-ray, and stutter-free playback should be possible... provided the rest of the network is fairly quiet.
Bandwidth is a topic that seems to confuse many people, here I'm talking about bandwidth in your house, and I hope that clears things up for you and yours. Soon I'll have discussions more in-depth about why wireless bandwidth isn't nearly what it should be, moreso than just being half-duplex. why we don't have full-duplex wireless, as well as internet bandwidth (why so slow). All this among many other topics to help clarify your digital life.
Be safe, enjoy.
Tuesday, January 17, 2012
MIMO the best thing ever?
I've just been studying wireless a lot in the last little while and I was considering how MIMO could be one of the best innovations since 802.11a.
For those that don't know, MIMO, or Multi-in, Multi-out (to paraphrase), is a transceiver method that uses multiple radios for a single line to enhance throughput and clarity of signal, being able to be fine tuned to even make reflections and phase shifting due to environmental disturbances, helpful to your wifi signal.
That being said, a lot of newer, mid to high end wireless b/g/n and a/b/g/n cards are coming out with multiple radio chains. The 802.11n standard supports up to 4x4 radio chains, but I have yet to see anything utilize that. Most commercial grade hardware has a max of 3x3 radio chains, which is to say 3 full transceivers in a single card. A good example of this would be the Intel 4965, 5300, and 6300 cards; all of which, I believe, are 3x3 radio chains for a/b/g/n wireless at 2.4ghz and 5ghz. The maximum rates differ, but that's another matter entirely.
My thought is, how useful is this? I mean that. It's beyond what I thought could be useful, but it really depends on what the hardware, driver, and software is capable of. I havn't checked into this, but if you have 3 almost entirely independent radio chains on a single card, would that not mean that you could, in theory, develop a WDS where roaming is entirely seamless? Having all wifi distribution traffic go through a single vlan to a central server that switches the 802.11 traffic into the 802.3 backbone? Then the question becomes, would you be able to separate a single radio chain for roaming and connection discovery? It could have the new connection, to a new AP, with better signal, fully authenticated before the previous (poorer signaled) connection is interrupted. Furthermore, you could simply configure it for a layer 2 notification, to now send all layer 2 packets destined for this layer3 address through this route instead (maybe by a gratuitous ARP or a ping type packet to the WDS Server?) - Meaning no more interruptions while roaming between nodes....
That is, provided the wireless nodes in your network support it.
Furthermore, network troubleshooting and analysis would be further simplified. Considering that you require 2 full channels on either side of the centre channel in order to not interfere with neighbouring networks, that interference could work in your favour when doing network analysis. With a 4x4 radio chain, you could potentially configure each radio chain to listen to a different channel, and catch all overlapping channel traffic too, getting a much faster, much clearer picture of the entire topology of the area that updates more frequently with less work on the hardware side.
I mean, the possibilities here are awesome. No more frequency hopping and incessant probing to try and find your AP.
Of course, the beamforming and everything else included in the 802.11n specification are also nice; and yes, they rely on the MIMO underpinnings to work, but that type of benefit, I believe, would be second to this... at least from a network adminstration point of view.
That's just my thoughts on it. I might be way off base or key, but I find this to be rather exciting. I know they're already working on the next standard, so we'll see.
For those that don't know, MIMO, or Multi-in, Multi-out (to paraphrase), is a transceiver method that uses multiple radios for a single line to enhance throughput and clarity of signal, being able to be fine tuned to even make reflections and phase shifting due to environmental disturbances, helpful to your wifi signal.
That being said, a lot of newer, mid to high end wireless b/g/n and a/b/g/n cards are coming out with multiple radio chains. The 802.11n standard supports up to 4x4 radio chains, but I have yet to see anything utilize that. Most commercial grade hardware has a max of 3x3 radio chains, which is to say 3 full transceivers in a single card. A good example of this would be the Intel 4965, 5300, and 6300 cards; all of which, I believe, are 3x3 radio chains for a/b/g/n wireless at 2.4ghz and 5ghz. The maximum rates differ, but that's another matter entirely.
My thought is, how useful is this? I mean that. It's beyond what I thought could be useful, but it really depends on what the hardware, driver, and software is capable of. I havn't checked into this, but if you have 3 almost entirely independent radio chains on a single card, would that not mean that you could, in theory, develop a WDS where roaming is entirely seamless? Having all wifi distribution traffic go through a single vlan to a central server that switches the 802.11 traffic into the 802.3 backbone? Then the question becomes, would you be able to separate a single radio chain for roaming and connection discovery? It could have the new connection, to a new AP, with better signal, fully authenticated before the previous (poorer signaled) connection is interrupted. Furthermore, you could simply configure it for a layer 2 notification, to now send all layer 2 packets destined for this layer3 address through this route instead (maybe by a gratuitous ARP or a ping type packet to the WDS Server?) - Meaning no more interruptions while roaming between nodes....
That is, provided the wireless nodes in your network support it.
Furthermore, network troubleshooting and analysis would be further simplified. Considering that you require 2 full channels on either side of the centre channel in order to not interfere with neighbouring networks, that interference could work in your favour when doing network analysis. With a 4x4 radio chain, you could potentially configure each radio chain to listen to a different channel, and catch all overlapping channel traffic too, getting a much faster, much clearer picture of the entire topology of the area that updates more frequently with less work on the hardware side.
I mean, the possibilities here are awesome. No more frequency hopping and incessant probing to try and find your AP.
Of course, the beamforming and everything else included in the 802.11n specification are also nice; and yes, they rely on the MIMO underpinnings to work, but that type of benefit, I believe, would be second to this... at least from a network adminstration point of view.
That's just my thoughts on it. I might be way off base or key, but I find this to be rather exciting. I know they're already working on the next standard, so we'll see.
Saturday, June 26, 2010
Radio
It's obvious that the radio we all knew from childhood of AM and FM is on the way out. If you're looking around at all, you know that. Between Satellite Radio, and Internet Radio, broadcast radio is being crushed out of the market.
Between internet and satellite, there's a lot of market share between them. Currently many people are buying cars with built-in satellite radio systems, which can be easily ignored by anyone competent and wishing to use some type of cell-phone based internet radio. With some service providers offering unlimited data on some cell phone plans, it's becoming more viable to have internet radio in the car.
However, a lot of people have, or will get a car with satellite radio integrated. The integration of the satellite radio plus the complexities of actually getting internet radio into your car, people will probably just pay for the service and forget about it. Which brings me to my next point... The primary company for Satellite Radio is just one company, Sirius Satellite, or XM, which are both the same company now.
Sirius/XM not only offers satellite, which you can listen to on the receiver built into your car, but internet radio you can listen to on any computer, as well as, iPhone, Blackberry and Android applications. The iPhone/BB/Droid markets are really the most significant place for any company to go for distributing a new application which would compete with Sirius/XM. A prime example of this competition are services like Pandora Internet Radio, and Grooveshark. I'm not sure what Pandora is peddling for their mobile application, since it's been a while since Pandora has been available where I live, but with Grooveshark, there's a subscription fee, for Grooveshark VIP status, that allows the use of the mobile app.
I dunno about you, but if I have to choose between listening to Internet Radio all the time (in the car, on the computer, on the go, etc), and Listening to satellite when I'm in the car (or on the go, depending on the receiver), and internet radio everywhere else, for fairly comparable prices.... I'm in favor of Satellite.
I know with my Satellite receiver, I can buy a home kit, that will hook up to my stereo at home; it also has a battery so I can hook up some headphones and listen on the bus, street corner, wherever. When I'm stationary at home, or away from my unit, I can always load up the Android app and listen wherever I happen to be (provided I get a 3g or wifi signal)... and if I happen to be somewhere strange, like a friends house, and want to listen to some tunes on my Sirius/XM subscription, I can login on the website and listen to all my favorite channels over the internet.
While some setups, like Pandora, have the ability to almost generate your own radio stations based on what YOU like, many people don't care to have that level of customization, or they just don't have the time to be able to tweak the settings so the radio stations are just-so. So even with that, they're still using an internet radio service on their 3g data plan... so then there's that.
Overall, I believe there will always be a place for Internet-only dedicated radio... I just don't think it's in the car. Thats why it'll be difficult to get rid of broadcast radio, and even more difficult to overtake satellite.
Between internet and satellite, there's a lot of market share between them. Currently many people are buying cars with built-in satellite radio systems, which can be easily ignored by anyone competent and wishing to use some type of cell-phone based internet radio. With some service providers offering unlimited data on some cell phone plans, it's becoming more viable to have internet radio in the car.
However, a lot of people have, or will get a car with satellite radio integrated. The integration of the satellite radio plus the complexities of actually getting internet radio into your car, people will probably just pay for the service and forget about it. Which brings me to my next point... The primary company for Satellite Radio is just one company, Sirius Satellite, or XM, which are both the same company now.
Sirius/XM not only offers satellite, which you can listen to on the receiver built into your car, but internet radio you can listen to on any computer, as well as, iPhone, Blackberry and Android applications. The iPhone/BB/Droid markets are really the most significant place for any company to go for distributing a new application which would compete with Sirius/XM. A prime example of this competition are services like Pandora Internet Radio, and Grooveshark. I'm not sure what Pandora is peddling for their mobile application, since it's been a while since Pandora has been available where I live, but with Grooveshark, there's a subscription fee, for Grooveshark VIP status, that allows the use of the mobile app.
I dunno about you, but if I have to choose between listening to Internet Radio all the time (in the car, on the computer, on the go, etc), and Listening to satellite when I'm in the car (or on the go, depending on the receiver), and internet radio everywhere else, for fairly comparable prices.... I'm in favor of Satellite.
I know with my Satellite receiver, I can buy a home kit, that will hook up to my stereo at home; it also has a battery so I can hook up some headphones and listen on the bus, street corner, wherever. When I'm stationary at home, or away from my unit, I can always load up the Android app and listen wherever I happen to be (provided I get a 3g or wifi signal)... and if I happen to be somewhere strange, like a friends house, and want to listen to some tunes on my Sirius/XM subscription, I can login on the website and listen to all my favorite channels over the internet.
While some setups, like Pandora, have the ability to almost generate your own radio stations based on what YOU like, many people don't care to have that level of customization, or they just don't have the time to be able to tweak the settings so the radio stations are just-so. So even with that, they're still using an internet radio service on their 3g data plan... so then there's that.
Overall, I believe there will always be a place for Internet-only dedicated radio... I just don't think it's in the car. Thats why it'll be difficult to get rid of broadcast radio, and even more difficult to overtake satellite.
Saturday, May 15, 2010
Wifi
I know my blog doesn't reach very far yet, and most of the people who have seen it, and will be reading it currently, don't have an extensive technical knowlege, so with that in mind, I move forward.
My blogs will become more technically driven, worded and oriented as time goes on, but if you find that I'm explaining simple technical concepts here, that's because I expect most of my readers to be non-technical people.
I just saw a video on youtube about a man who boosted his wifi signal strength for less than $1, using an old box and some aluminum foil. I'd like to throw support behind the guy, and he's got the concept right, but the implementation is clearly done by someone without technical knowledge of how wireless functions.
for the purposes of this article we'll be talking about the most common wifi, which is 802.11g, 2.4ghz wireless.
Here's a brief rundown: In optimal conditions, a wireless router produces an alternating current through a wire, at 2.4 billion iterations per second, which produces an electromagnetic wave, which travels through space towards its intended target. this wave travels at light speed in a vacuum, but since we don't live in one, it's slowed down by air and whatnot. Regardless, at 2.4Ghz, and the distance that an electromagnetic wave can travel in one second, we can determine the wavelength. The wavelength is how long one hz, or one iteration of the wave occurs (meaning it goes up, comes down, and comes back to center). from all the math, we can determine that a 2.4ghz wave has a wavelength of aproximately 12.5cm (or 4.9something inches). all this aside, the 802.11 protocol has been designed with reflections and noise accounted for, so your computer isn't expecting a clean wifi signal to begin with. with this guy's reflector being... what? 2cm from his antennas, it causes a reflection that is out of phase.
brifely, phase is where in the wave you are, it's measured in degrees, starting at zero degrees from centre, going upwards to the highest level, at 90 degrees, returning to the zero line, at 180 degrees, and the lowest level at 270 degrees, then returning to zero again at 360 (or zero) degrees.
the out of phase signal is accounted for by the wifi card and it interprets it with the rest of the data on the wireless channel, but it makes for an uneven waveform (which actually damages the potential signal quality).
The intention is to put two waves, in phase, and by doing so, the two compliment each other and amplify each other. to do this, the reflector should be one-half wavelength away from the antennas on the opposite side of the antenna related to the desired target (aka behind it).
all this techobabble means that if you want to boost your signal better, you need to have the reflector exactly 6.25cm behind your antennas (for 2.4ghz). obviously, he's far under this, I doubt he's even 1/4 wavelength behind the antennas, which means he's probably giving two waves to the target that are 1/8th wavelength, or 45 degrees out of sync. albeit, it will still be more powerful than without the reflector, but move that reflector to 1/4 wavelength and you would actually have a negative impact on wireless performance.
Optimally, the reflector should be parabolic, or rounded, around the antennas, maintaining a constant distance from the signal origin.
I hope this explains some of the nuances of wifi technology and signal enhancing technologies. his idea is good and it's a very simple and effective way to increase signal strenth (if done right).
I hope you all enjoyed, good luck if you're trying this, and happy wifi-ing.
My blogs will become more technically driven, worded and oriented as time goes on, but if you find that I'm explaining simple technical concepts here, that's because I expect most of my readers to be non-technical people.
I just saw a video on youtube about a man who boosted his wifi signal strength for less than $1, using an old box and some aluminum foil. I'd like to throw support behind the guy, and he's got the concept right, but the implementation is clearly done by someone without technical knowledge of how wireless functions.
for the purposes of this article we'll be talking about the most common wifi, which is 802.11g, 2.4ghz wireless.
Here's a brief rundown: In optimal conditions, a wireless router produces an alternating current through a wire, at 2.4 billion iterations per second, which produces an electromagnetic wave, which travels through space towards its intended target. this wave travels at light speed in a vacuum, but since we don't live in one, it's slowed down by air and whatnot. Regardless, at 2.4Ghz, and the distance that an electromagnetic wave can travel in one second, we can determine the wavelength. The wavelength is how long one hz, or one iteration of the wave occurs (meaning it goes up, comes down, and comes back to center). from all the math, we can determine that a 2.4ghz wave has a wavelength of aproximately 12.5cm (or 4.9something inches). all this aside, the 802.11 protocol has been designed with reflections and noise accounted for, so your computer isn't expecting a clean wifi signal to begin with. with this guy's reflector being... what? 2cm from his antennas, it causes a reflection that is out of phase.
brifely, phase is where in the wave you are, it's measured in degrees, starting at zero degrees from centre, going upwards to the highest level, at 90 degrees, returning to the zero line, at 180 degrees, and the lowest level at 270 degrees, then returning to zero again at 360 (or zero) degrees.
the out of phase signal is accounted for by the wifi card and it interprets it with the rest of the data on the wireless channel, but it makes for an uneven waveform (which actually damages the potential signal quality).
The intention is to put two waves, in phase, and by doing so, the two compliment each other and amplify each other. to do this, the reflector should be one-half wavelength away from the antennas on the opposite side of the antenna related to the desired target (aka behind it).
all this techobabble means that if you want to boost your signal better, you need to have the reflector exactly 6.25cm behind your antennas (for 2.4ghz). obviously, he's far under this, I doubt he's even 1/4 wavelength behind the antennas, which means he's probably giving two waves to the target that are 1/8th wavelength, or 45 degrees out of sync. albeit, it will still be more powerful than without the reflector, but move that reflector to 1/4 wavelength and you would actually have a negative impact on wireless performance.
Optimally, the reflector should be parabolic, or rounded, around the antennas, maintaining a constant distance from the signal origin.
I hope this explains some of the nuances of wifi technology and signal enhancing technologies. his idea is good and it's a very simple and effective way to increase signal strenth (if done right).
I hope you all enjoyed, good luck if you're trying this, and happy wifi-ing.
Subscribe to:
Posts (Atom)