Wireless networks have come a long way in the last 15 years. And even today, unstable WiFi speeds are a problem in some situations. There are a lot of things that can influence this, from your router settings to interference in your home to the distance between devices. Fortunately, there is almost always a way to fix low speed data transmission.

If you've ever tinkered with your router's settings, you've probably noticed the word "channel." Most routers have a set of channels set to auto mode, but I'm sure many have seen a dozen channels on that list and wondered what they do and which one is faster. Well, it turns out that some channels are indeed faster, but this does not mean that you need to open the settings and change their values. Read on to learn more about 802.11 channels, interference, and the difference between 2.4GHz and 5GHz WiFi.

Channels 1, 6 and 11
First of all, let's talk about 2.4 GHz, since almost all WiFi installations use this band. 802.11ac, which debuted in 2013, is moving towards 5GHz adoption, but thanks to backwards compatibility and dual-radio routers, the 2.4GHz band will be mainstream for a long time to come.

All versions of Wi-Fi, up to 802.11n (A, B, G, N) between frequencies 2400 and 2500 MHz. These 100 MHz are divided into 14 channels of 20 MHz each. As you have probably already calculated, 14 by 20 is much more than 100 MHz, as a result of which each channel is connected to at least two (usually 4) other channels (see diagram above). As you can imagine, using overlapping channels is not very good for devices - this is one of the main reasons for poor wireless throughput,
Luckily, channels 1, 6, and 11 are far enough apart that they don't overlap. On a non-MIMO installation (i.e. 802.11 a, b or g), you should always try to use channel 1, 6 or 11. If you are using 802.11n with 20 MHz channels, then you can also use 1, 6 and 11 , if you want to use 40 MHz channels, then be aware that the radio waves can be very congested unless you live in a private house in a sparsely populated area.

Which channels to use in a built-up area?
If you want maximum throughput and minimum interference, channels 1, 6 and 11 are best choice, but depending on other wireless networks in your area, one of these channels may be much more convenient than the others.
For example, if you are using channel 1 and someone behind the wall is using channel 2, your throughput will drop. In this situation, you will have to change the channel to 11 to completely avoid interference, although 6 will also work. It may be tempting to use a channel other than 1, 6 and 11, but remember that you will then be causing interference.
Ideally, it's best to talk to your neighbors and set each router to channels 1, 6, and 11. Keep in mind that interior walls can greatly weaken the signal. If there's a brick wall between you and your neighbor, then you can probably both use channel 1 without interfering with each other. But if it's a thin wall, you have to use different channels.
There are ways to help you find the clearest channel, such as Vistumbler, but it's often easier to switch between channels 1, 6, and 11 until you find the clearest signal. If you have two laptops, you can copy the file between them to test the bandwidth of each channel.

What about 5 GHz?
The best thing about the 5 GHz frequency (802.11n and 802.11ac) is that it has much more free space at higher frequencies, which offer 23 non-overlapping 20 MHz channels.
It is also worth noting that starting with 802.11n wireless technologies are becoming more advanced compared to 802.11b and g. If you have a modern 802.11n router, it most likely has the ability to select the correct channel and change output power to maximize throughput and minimize interference. If you are using 5 GHz and your walls are not paper-thin, then you can use channels of 40, 80, and 160 MHz.
After all, as all equipment upgrades and moves towards 5GHz, choosing the right channel becomes a thing of yesterday. Of course, there are still times when it makes sense to configure the router's channel selection, but when you're dealing with MIMO, the router will do its thing.

When considering 802.11 ac deployment, understanding its underlying technology is critical. Despite its enormous benefits, 802.11ac is still susceptible to traditional problems that negatively impact WiFi network performance: non-WiFi interference, cross-channel interference, poor signal quality, noise, and channel sharing with legacy clients that have lower bit rates. . These challenges can only be successfully addressed with a rigorous implementation plan for this revolutionary technology. Resist the urge to just buy a few 802.11ac access points, plug them in, and let users use them.

The main stages of deploying an 802.11 ac network are:

1. Careful site planning and assessment

2. Checking for correct installation

3. Troubleshooting and optimization

We'll describe the considerations and best practices for each step, and provide recommendations for achieving the best performance and signal quality.

Site planning and assessment

The new 802.11ac standard is expected to be implemented in parallel with older a/b/g/n systems. Since the 802.11 ac standard has backwards compatible with a/n systems using the 5 GHz frequency band, there is no need to completely remove these “old” access points. However, it is critical to understand what devices are already competing for radio spectrum and how 802.11 ac access points can complement the environment to achieve design goals. The planning phase will include a pre-deployment study to determine the current device configuration, noise levels, sources of interference, signal coverage, and network capacity.

Initial site investigation

Before purchasing and installing any 802.11 ac equipment or removing any existing access points, you must determine the current state of your WiFi environment. Determine sources of interference, signal coverage, channel availability in the 5 GHz band and the current configuration of all installed devices 802.11a/n. This may be accompanied by an "AP-On-A-Stick" study where one 802.11ac access point is enabled and deployed and the impact of the environment on coverage and throughput is noted.

Required Bandwidth

Next, you need to consider the target throughput of the project. This will need to include a calculation of the level of bandwidth required by user applications and take into account the number of users of each application. Users can connect from smartphones, tablets, laptops and other client WiFi devices, which will shape the need for adequate coverage for devices with different capabilities.

For example, if a given area expects five users to connect from a maximum of 15 devices (three per user), depending on how much voice services, video services or just web services are required, we can estimate the required bandwidth to be approximately 30 Mbps. This will of course depend on the applications used and the number of concurrent users connecting. To support user density, typically plan for no more than 20 active devices per access point.

Required frequency band per application 1

Application by type of use	Nominal bandwidth
Internet - entertainment	500 kilobits per second (Kbps)
Internet - training	1 megabit per second (Mbps)
Audio - entertainment
Audio - training
Streaming or Video on Demand - Entertainment
Streaming or Video on Demand - Training
File sharing is fun
File Sharing - Training
Online testing
Device backup	10-50 Mbit/s

1 Jim Florwick, Jim Whiteaker, Alan Cuellar Amrod, Jake Woodhams, Wireless LAN Design Guide for High Density Client Environments in Higher Education(Wireless Internet Access Design Guide for a Wireless Internet Environment) high density clients in higher education)(Cisco Design Guide, 2013)page. 8 .

Channel Allocation Considerations

The 802.11 ac standard allows the use of 80 MHz channels in the 5 GHz band, which are formed by effectively combining four 20 MHz channels. When selecting an access point configuration, one primary 20 MHz channel, such as 36, is configured to act as a beacon channel and a backup channel. If an older standard device wants to connect to the access point, it will be able to use this primary 20 MHz channel to connect and operate. However, since this separate channel is part of a common 80 MHz composite channel, it will slow down the 802.11ac client's transmission to the access point when the primary 20 MHz channel is used.

The best method for deploying 802.11 ac access points is to use them in a rotation of two to five available channels 80 MHz. On one access point, channels 36 - 48 are combined, and on another, channels 52 - 64. If in a certain area there is a need to overlap these channels, configure different primary channels for them 36, 44, 52, and 60, respectively. This will leave enough channel spacing to support older standard devices that must connect to 20 MHz channels without creating crosstalk between channels.

Deployment and Validation

After carefully determining the required throughput and coverage area, configure and commission 802.11 ac access points according to your project plan. This doesn't mean simply removing old access points and adding new 802.11ac access points in the same locations. When planning the configuration and placement of access points, consider the following considerations:

• Switching infrastructure

The access point connections to the network may need to be better than what was previously required. Since throughput may approach 1 Gbps, the connection between the access point and the access switch should be at least 1 Gbps, with a 10 Gbps uplink to the switching center. 802.11 ac access points require power using 802.3at (PoE+) rather than 802.3af due to the higher antenna power requirements electrical power. This may require either upgrading the switch or using an in-line power injector.

• Channel width

Depending on user needs, 802.11 ac access points can be configured with channel widths of 20 MHz, 40 MHz or 80 MHz. 80 MHz channels have more capacity, but on many networks only two such channels may be available. In a dense environment with hundreds of possible users, more access points will be required to provide adequate connectivity, which may force the use of 22 non-overlapping 20 MHz channels. Carefully calculate user density and expected application throughput, as this information will be critical in deciding the number of access points required and the choice of channel width to use. You also need to carefully analyze the mix of 802.11 ac clients and 11a and 11n clients. If the majority of clients are 11a/n, it may make sense to use 20 or 40 MHz channels, since the remaining 80 MHz channel bandwidth will remain unused while the 11a/n client is running.

Visualization of channel width 20/40/80/140 MHz inAirMagnet Survey

• Access Point Coverage

Different zones have different network bandwidth requirements. Depending on the density of users and applications, it may be that high throughput is required only in certain areas, while areas of corridors and lobbies are reserved for data transmission. Determining antenna power and directivity, cell size, and ideal deployment method may require detailed information from the access point manufacturer.

After calculating user needs before physical installation access points, you can use the AirMagnet Planner program to simulate a virtual WiFi environment. To ensure adequate coverage and capacity, the number of access points and their location can be set, taking into account wall materials and sources of interference. Using this data, you can then physically place access points in the planned zones.

To determine whether the environment provides the expected coverage and intended throughput, the premises must be tested after deployment. To check, you can use both active measurement of network throughput for the user, and passive research with measurement of signal, noise, interference, channel overlap and others important parameters entire WLAN environment. An active survey should include testing both upstream and downstream throughput from the 802.802.11 ac instrument. To ensure that all normal parameters are within normal limits during testing, such testing should be conducted during peak traffic hours.

An active survey is launched using AirMagnet Survey Pro iPerf; at the same time measured and displayed in real time accessible to the user throughput, and areas with low throughput are identified. It is recommended to run a multi-adapter test, which allows you to run both passive and active tests simultaneously. This allows you to measure all the required data points in one go.

Troubleshooting, optimization

If the survey does not meet any of the user throughput requirements, adjustments can be made to ensure that performance targets are met. You can use the Airwise Policy check feature in AirMagnet Survey Pro to determine which wireless factors in your environment are contributing to performance degradation. A specially designed workflow is provided to help you make the right adjustments in the right places to achieve your desired goals.

Adjustments may include changing the location of access points, installing additional access points, adjusting the channel plan, eliminating sources of interference, or adjusting transmit power, which affects cell size. To ensure that your goals are achieved, follow the adjustments recommended by Airwise, test the environment with a different multi-adapter, and conduct active and passive testing.

Finally, a final check using Survey Pro's iPerf feature will prove that the network has been successfully built to meet the user's needs.

Successful implementation of 802.11 ac

AirMagnet Survey Pro makes it easy to see all the benefits of implementing the 802.11 ac standard. But without careful planning, testing, and optimization, the potential benefits of 802.11ac will be lost due to legacy environments, excessive noise, poor channel planning, or poor access point placement.

To get the most out of the 802.11 ac standard, you can use Fluke Networks' AirMagnet family of WiFi analyzers, for example.

Much more often than we would like, users are faced with the problem of a drop in Internet access speed. There are a lot of reasons for this, and in this article we will look at several of the most common and easily solvable reasons for a drop in speed, and also touch on the topic of how to increase the speed of a router.

But before determining the reasons, you must meet some requirements, namely, the device must be in sight to see the indicator LEDs, and you must have a valid login and password to enter the settings menu. Let's find out why this is necessary.

Unauthorized connections

A very common problem of speed drop when your wireless Wi-Fi networks Freebie lovers are joining in. This is, of course, provided that you have set a password for the connection. If this is the case, it’s time to install it.

To do this, go to the router settings and go to the “Wireless Mode”, “Protection” menu.

Setting a Wi-Fi password

We enter the password in the “PSK Password” field, and the more complex and longer the password, the more difficult it is to hack it. In this case, you need to remember that it cannot be shorter than eight characters, and letters other than in English and numbers.

Save the settings, that's it Wi-Fi protection completed. If the speed does not return to normal, that is, does not increase, then read on.

Hacking Wi-Fi password

There is popular wisdom - there is no absolute protection. If there is a password, then it can be hacked. Unfortunately, Wi-Fi is no exception, and there are a number of programs for cracking the key (they will not be discussed in this article). To determine whether a neighbor has hacked our password and whether this is the reason for the drop in speed, there are at least two ways.

The first method is to look carefully at the indicator lights on the front panel of the router.

Front panel indicators

We are interested in the WLAN indicator - activity wireless network. At the same time, we turn off all our wireless devices (computer, laptop, smartphone and everything else), in a word - we don’t use Wi-Fi. If the indicator continues to blink, then the router continues to transmit data to someone, which means that someone is still connected to us. Let's figure out who it is through the settings menu.

We return to the settings menu, go to the “Status” menu, then the “LAN clients” submenu.

Wireless Clients

This list should be empty, since all our wireless devices are disabled and no one is connected to the router. If there are connections in the list, then the fact of hacking is obvious - someone is connected to you.

In this case, you can make a tricky move - open access to the Wi-Fi network (the password still doesn’t help), but set up a filter by mac addresses, in the list of which include all the physical addresses of only our devices. Go to the “Wi-Fi” menu, then the “MAC filter” submenu.

List of trusted mac addresses

Having generated a list of physical addresses, go to the “Filter Mode” tab.

mac filter mode

And set the mode to “Allowed”. That's it, now the router will only work with devices whose address is in this list, ignoring everyone else. A password is no longer even required.

Router Location

Many are confident that if the router is wireless, then it can be placed anywhere, and the signal will propagate without problems under any conditions. But after rearranging the furniture in the apartment and, accordingly, “moving” the router to another corner of the room, the Internet speed suddenly dropped. In such a situation, it is very likely that the location of the router is simply not the best.

Check the following:

1. Isn't it too much long distance between the computer and the router. The weaker the receiving signal, the lower the transmission speed;
2. Are there any obstacles between them in the form of load-bearing metalized walls or metal sheets? Any metal greatly distorts the radio signal;
3. Check the antenna. If the antenna is removable, remove it, clean the antenna connection socket, and put it back in place. It also makes sense to purchase an antenna with a higher gain (dBi). For example - if you have a coefficient of 2 dBi, then buy 5 dBi;
4. Are there any radio phones between the computer and the router? microwave ovens, bluetooth devices. The fact is that the above devices also emit radio waves with a frequency of 2.4 GHz, which interferes with our network.

Change channel

If there are no problems with these conditions, then you should try changing the radio channel. This is done in the “Wi-Fi” settings menu, in the main settings.

Changing the Wi-Fi channel

By default, the “Channel” column is usually set to “Auto”, that is, the router itself selects the most free channel. But he does not always do this adequately, and chooses far from the best option. Try manually experimenting with the channels, maybe you will find the freest one, and if the combination is successful, the speed will increase noticeably.

It is also worth paying attention to the wireless network standard - it should be at least “N” (If, of course, the router supports it).

Setting up Wi-Fi mode

If you select the mixing mode, then the “n” mode must be present (150 Mbit/s for devices with one antenna).

Changing the channel width

Many, but not all, routers allow the user to change the channel width - 20 MHz or 40 MHz.

Selecting Wi-Fi channel width

Even if your value is 40, still try changing it to 20.

It should be remembered that the 40 MHz width increases the speed only if the signal level is good and stable! If the connection between the router and computer is poor, increasing the channel width can, on the contrary, make the situation even worse!

If you have an old router, with weak processor, then it’s worth remembering that the entire flow of information passing through the router must be analyzed, and a service such as a firewall can greatly delay the flow.

As an experiment, try turning it off. This is done in the “Security” menu.

Router firewall

We look for the “Firewall” subgroup and select the “Disable” value.

Line, provider

And finally, the fault may not be in the router at all, but in the wires running from the provider to your apartment. To find out whether this is true or not, you need to call the provider’s support service and call a technician who will measure the condition of the line. Perhaps there is a loose contact somewhere, or moisture has gotten into the line, and nothing can be done in this case without repairing the line.

Finally, a video about the myths that using tin cans can increase the signal level:

I haven't touched one important point- use of 40 MHz wide networks in the 2.4 GHz band. Apparently in vain, since ingrained in the minds of readers gg opinion (not without effort on the part of the founding fathers of the resource) categorically does not accept the very idea of ​​​​the possibility of using “wide” networks in the 2.4 GHz range - which is easy to verify by reading the comments under the mentioned article. Today I will try to dot, if not all, then many i’s regarding this issue. And at the same time, I’ll destroy a couple more myths and legends that have developed around the operation of Wi-Fi networks (hello to Adam Savage and Jamie Hyneman).

What are the arguments of opponents of 40 MHz networks based on? On the fact that:

1. there are catastrophically few non-overlapping channels in the Wi-Fi range of 2.4 GHz, so the minimum channel width of 20 MHz is our (their) everything;
2. 40 MHz networks create strong interference with other Wi-Fi networks operating nearby. Horror!

Well, let's debunk the myths in order.

About the dangers of public opinion

Established public opinion does not necessarily mean that it is automatically correct. After all, this opinion is formed under the influence of certain individuals who formed and defended it. And many of these individuals, to put it mildly, were far from the smartest. It was thanks to deep-rooted public opinion that Giordano Bruno burned, Galileo suffered, Georg Ohm lost his job, etc. and so on. Albert Einstein also openly laughed at “public” opinion. Now I will prove to you that the great physicist was right...

So, in every second, if not every first, article devoted to Wi-Fi networks, they persistently explain to us that in the 2.4 GHz range there are only 3 non-overlapping (i.e., not creating strong interference with each other) channels - 1, 6 and 11. What kind of 40 MHz channel width can we talk about in this case, if one “wide” network “eats” b O most of the available radio spectrum?! The opinion about 3 non-overlapping channels is so firmly rooted in the minds of the people that I won’t even argue with it. I'll just say that this is a blatant lie. Complete nonsense. Bullshit. Zvezdezh. Call it what you want. If you lean out a little and look out of the public tank, the reality will be noticeably better: in the European region, where we also belong, 4 non-overlapping 20 MHz channels are available in the 2.4 GHz Wi-Fi range: 1, 5, 9 and 13 Only this way and no other way. The only equipment that does not allow you to work in these ranges is equipment purchased directly from the USA and imported to Ukraine, or flashed with American firmware - but such devices are in tiny numbers. Therefore, even within one small cramped room, two independent “wide” 40 MHz Wi-Fi networks can work quite successfully, without interfering with each other at all.

What about interference to neighboring networks? After all, we all here are very worried about the quality of Wi-Fi connections in our neighbors and, in general, about the world of Wi-Fi throughout the world!

Misunderstanding

In support of their “theory of the harmfulness of wide networks,” 20 MHz apologists sing in unison a tune about the strong interference from the 40 MHz network to neighboring Wi-Fi networks. As convincing arguments, they even cite program graphs showing the presence of a mass of some kind of Wi-Fi networks around.

However, the problem is that even people who seem to have a good understanding of the topic of Wi-Fi have little idea of ​​what exactly these graphs show. What can we say for other users? So, these graphs show something completely different from what we are used to seeing on charts comparing the performance of processors or video cards. But ordinary people interpret what they see this way. Moreover, it is realistic to be afraid that the 40 MHz network will “drown out” with its “powerful” signal all these weak sprouting networks nearby. The problem is not even that 40 MHz channel width has nothing to do with network power at all. The problem is that “Decibel” and “Decl” in the understanding of most of these people mean approximately the same thing. No, I don't blame them for this at all. This is fine. But let me try to explain the difference in accessible language.

How do decibels differ from other “parrots” that measure the performance of video cards and processors? Decibels help to display the difference between indicators, the magnitude of which differs not by units or tens of magnitudes, but by an order of magnitude. For example, a difference in signal strength of Wi-Fi networks of 10 dB means a difference of exactly 10 times, a difference of 20 dB is already 100 times, and 30 dB is a thousand times. On a regular chart in “parrots” it would be very difficult to visually depict the difference in such values. After all, the minimum value on the diagram simply risks being invisible to the “naked eye.” That's why decibels come to the rescue. So, 5 dB is already a difference in signal power of 3.16 times, 1 dB is 1.26 times. A difference of 1 or 5 dB is of course too small, although there is real networks, working quite normally even in such difficult conditions. But a 10-20 dB difference in signal strength, which most users usually have (of course, signal strength measurements should be carried out close to the router or access point, and not on the balcony of a neighboring house) is already quite enough to avoid significant interference from other networks. And at the same time, do not interfere with the normal operation of these other networks, because the signal from our Wi-Fi device, spreading to the area of ​​​​another network, weakens proportionally. And it doesn’t matter at all whether the width of the network used is 20 or 40 MHz. Why do I think that a difference of 10-20 dB is enough?

Everyone is in the way here!

I’ll tell you a terrible secret: non-overlapping Wi-Fi channels in the 2.4 GHz range physically do not exist. At all. How so? It’s just that diagrams of applications like inSSIDer, Acrylic Wi-Fi Home, Wifi Analyzer and others like them do not show us the whole truth...

When operating, a Wi-Fi antenna emits not only a useful signal, but also interference - this is simply what it is supposed to do according to the laws of physics. The radiation power of the antenna is distributed approximately as follows (according to Zyxel):

For convenience, 0dB is taken as the zero level of maximum power, but the picture can be extrapolated quite successfully. As you can see, at a signal power of -28 dB from the maximum, even one channel already successfully occupies a 40 MHz bandwidth. And at a signal level of more than -40 dB from the maximum, even the most distant channels 1 and 13 “cross” quite successfully. Is this any significant problem for the operation of Wi-Fi networks? No. At the same time, some gagadget readers did not hesitate to post screenshots showing the difference in signal strength with neighboring networks by at least 30 dB, and were absolutely confident that they were right regarding the impossibility of using “wide” 40 MHz Wi-Fi networks. True, in the end they were unable to explain the reason for their confidence...

For what?

What is the whole garden for? What is the practical benefit of 40 MHz? And why is 20 MHz worse? I answer. Using a specific example. At 40 MHz channel width, performance wireless wifi network reaches 13-16 MB/s, with a width of 20 MHz - only about 7-9 MB/s. Is it worth sacrificing Wi-Fi network speed for the sake of some ridiculous prejudices? I don't think it's worth it. However, you always have the right to your own opinion, indistinguishable from public opinion.

P.S. Even if your neighbor has built a powerful network, you can avoid significant interference from it simply by changing the polarization of the antennas of the router or access point, if the antennas allow it. Moreover, if there is strong interference from neighboring networks, many equipment manufacturers rightly recommend reducing the signal strength of your Wi-Fi network to improve communication. I won’t go into details, but this way it’s simply easier for a router or access point to filter “strong” interference. However, this is a completely different story from the field of physics, which I am not going to write about here.

The implementation of Wi-Fi 802.11n in modern phones and tablets leaves much to be desired. The new standards 802.11ac and 802.11ad promise gigabit speeds in the future and have been discussed for several years. Broadcom and other companies have been offering chipsets to manufacturers since mid-2012. When will they begin to be implemented and which devices will receive support? high-speed versions Wi-Fi first?

Tricks in implementing 802.11n

The history of the transition to new standards repeats itself surprisingly accurately. One of the first smartphones in Russia to support the draft version of 802.11n was the HTC HD2, which appeared in 2009. Its speed was only slightly higher than that of smartphones with Wi-Fi version "g". It corresponded to the minimum implementation of version “n” and made you smile bitterly, remembering the promised 600 Mbit/s. Years have passed, the final version of the standard has long been approved, but everything remains the same.

Until now, most mobile devices support the 802.11n standard in its minimal version. One 20 MHz wide channel at 2.4 GHz - that's all. This limits the theoretical speed limit to 72 Mbps. In real conditions, the actual speeds demonstrated are even lower.

Real Wi-Fi connection speed (image: anandtech.com)

Please note: version “g” and even “a” look in practice quite competitive compared to the stripped-down Wi-Fi “n” options. Marketers like to make references to the upper threshold of the standard - the notorious 600 Mbit/s. They could be achieved using four 40 MHz wide channels at 5 GHz, but this option is rarely found even in routers. Most mobile devices use one or two transceivers, each with its own antenna. Only in a few laptops (for example, MacBook Pro) you can find three. Accordingly, the maximum speed is 3 x 150 = 450 Mbit/s. I think there is not a single smartphone or tablet in the world with three or four antennas.

Real Wi-Fi speeds continued (image: anandtech.com)

More recently, some smartphone models began supporting speeds of 150 Mbps. Was at MWC 2013 Huawei Ascend P2 is a mid-range smartphone with two Wi-Fi antennas, which was presented as an advantageous difference. A little earlier, Ascend Mate was presented in a similar way. However, in addition to doubling narrow channels, you can increase the width of a single channel to 40 MHz, and the result will be the same - 150 Mbit/s.

It is noteworthy that Wi-Fi speed does not depend on the price of the device. Not only the iPhone 5 and Huawei Ascend Mate, but also the budget Philips W626 can work via Wi-Fi “n” twice as fast as most others. The problem is that manufacturers usually do not indicate the features specific model. In the specifications they write “802.11 b/g/n” everywhere without any clarification.

“ad” version as a Bluetooth competitor

With Wi-Fi of the following standards, the situation is even more interesting. Contrary to the designation, 802.11ad (WiGig) will not be the successor to 802.11ac. This parallel development standard was created from the ground up and will soon likely replace Bluetooth. Its task is high-speed wireless connection at short distances. The table below shows some implementation features and theoretical speed limits for different versions Wi-Fi using one channel.

Approximately, the 802.11ad standard will be limited to speeds of up to 7 Gbit/s, but the possibility of further increasing it is being considered. Due to the nature of high-frequency signal propagation, devices must be in direct line of sight and within a few meters of each other. Unlike 802.11ac, WiGig is not backwards compatible with other versions of Wi-Fi because its operating frequency is 60 GHz.

Version “ac” – expectations and concerns

Version “n” will begin to be replaced by 802.11ac by the middle of the year. It has been in development since 2008 and the final draft version was announced only five years later. The standard is now estimated to be 95% complete, whatever that means. Without waiting for final official approval, manufacturers began producing the corresponding chips a year ago. Practice has shown that this approach was more than justified in the case of version “n”. The hardware platform has not been modified, and software changes are easy to make with a firmware update. One of the first modules to work according to the 802.11ac standard (backward compatible with b/g/n) was released by TriQuint. The TQP6M0917 chip, which appeared in mid-2012, has dimensions of 4 x 4 x 0.5 mm, which allows it to be used in mobile technology.

According to representatives of another large company that produces chipsets for communication modules (Broadcom), the first devices supporting 802.11ac will appear en masse by the second half of 2013. Qualcomm representatives also agree with this assessment. Traditionally, routers and network adapters. Smartphones and tablets with 802.11ac will become commonplace a little later, but some of their representatives will go on sale in the very near future.

High-speed Wi-Fi of the fifth generation is expected in the iPhone 5S (symbolically) and all smartphones based on the Qualcomm Snapdragon 800 platform. By analogy with the history of the implementation of version “n”, most likely we are talking about the basic implementation and single-channel solutions. Depending on the channel width (from 80 to 160 MHz), the speed of new smartphones over Wi-Fi will be limited to a theoretical limit of 433 or 866 Mbit/s.

Smartphones with Broadcom BCM4335, Redpine Signals RS9117 and Qualcomm Atheros WCN3680 chips will connect at a speed of 433 Mbps. More high speeds So far they have been announced only in chips for laptops and routers.

Backward compatibility leaves yet another loophole for dishonest marketing. A device that supports the draft version of 802.11ac can use the now common channel widths of 20 and 40 MHz. With such a formal implementation, the speed bar will drop below the minimum 433 Mbit/s.

Among other important features of the standard, the Beamforming method of improving communication quality is noted. It allows you to take into account the phase difference of the reflected signals and compensate for the resulting speed losses. Unfortunately, Beamforming involves the use of multiple antennas, which so far limits its application to laptops.

It is expected that in a number of use cases new standard will increase the time battery life. By transferring the same amount of data faster, the chip will be able to enter a low-power mode earlier.

As can be seen from the examples presented, technically nothing prevents you from increasing the data transfer speed over Wi-Fi right now. This does not require introducing new standards - potential existing version“n” in mobile devices not even half opened. If speed is critical for you, try testing your smartphone or tablet by connecting it to a decent router.