3r33333. 3r3-31. The continuous hyip around the gigabit Wi-Fi speeds of modern standards provokes engineers to clarify this topic in a way that everyone can understand. 3r33524.  3r33333. What are marketers trying to pull behind their ears? What do engineers say? Where is the truth? 3r33524.  3r33333. As always, somewhere nearby. What bandwidth is expected in real conditions and why - you will find the answer in this article. If there is absolutely no time to read, but I want to know the magic number - 75 Mbps per dual band access point, on all 3r3496. . Who are interested in the details, read on. 3r33524.  3r33333. 3r33524.  3r33333. 3r33538. 3r33524.  3r33333. The article is based on Wi-Fi Throughput material from Devin Akin, who has been in the subject of wireless networks for over 20 years as well as the co-founder of the educational program 3r319. CWNP 3r33538. (aka CWNE # 1). 3r33524.  3r33333. I simply asked him if his article could be translated, and he immediately replied: “Yes, I will be delighted”. 3r33524.  3r33333.
like this, everything is just solved in linkedin
-Hello Devin. If you’re referring to your web site? It will help to explain reality. 3r33524.  3r33333. -Hi Maksim. I would be delighted for the Russian IT community. 3r33524.  3r33333.
3r33524.  3r33333. I, in turn, delighted with the open community of Wi-Fi engineers. So let's go. 3r33524.  3r33333. 3r33524.  3r33333. What to expect from 20 MHz? 3r33524.  3r33333. 3r33524.  3r33333. First you need to understand what to expect from a 20 MHz channel with a standard assortment of client devices. Suddenly, who does not know, SS (Spatial Stream) is a Spatial Stream (PP). Understanding of the technology of spatial multiplexing or MIMO, which appeared back in ???n and for almost 10 years, pleases with increased speed due to the simultaneous transmission of several BCPs simultaneously. Very good article on the topic of MIMO 3r33535. written by Andrey Kuznetsov, thanks to him for his clear language. 3r33524.  3r33333. To work with several software, an access point or client needs to have on board several transceivers with antennas (the first two numbers in the characteristics, for example, 2 × 2: 2), with all energy overheads. 3r33524.  3r33333. 3r33524.  3r33333. Below is excellent graphics from
Andrew Von Nagy . 3r33524.  3r33333. 3r33524.  3r33333. 3r361. 3r33524.  3r33333. 3r33524.  3r33333. In this picture, with all 1 × 1: 1 clients, each of which transmits a 3 Mbit /s stream, the airtime (airtime) of a pure 20 MHz channel is saturated. With the disposal of the channel of about 75-80% full saturation occurs. As a result, the total bandwidth of the channel is approximately 30 Mbit /s, or a total of 10 devices per 1 AP (Access Point). 3r33524.  3r33333. If all clients can work with 2PP (2 × 2: 2), then there is a chance to get a total bandwidth of about 65 Mbit /s and 21 devices at the same time, not bad, right? 3r33524.  3r33333. 3r33524.  3r33333.

What does bandwidth rest on? 3r33462. 3r33524.  3r33333. It is important to note that we can change the number of clients and bandwidth per client, but still we will always rest on the restriction due to airtime saturation. For example, if each device connected to the TD needs 2 Mbit /s and they are single-threaded (1PP), then I will receive a maximum of 15 simultaneously working devices until I rest on saturation at 30 Mbit /s (2 × 15 = 30). The same mathematics will be with 2pp clients, with 32-33 clients at a speed of 2 Mbit /s, we rest on saturation with a total speed of 65 Mbit /s. 3r33524.  3r33333. 3r33524.  3r33333. Good The predictable ratio of customers in modern networks is 2/3 of 1PP per 1/3 of 2PP. Customers with 3PP (like MacBook Pro) are less than 1%. Knowing this ratio, we can expect that the average TD with a free (from interference and neighbors) channel will become saturated at about 45 Mbit /s. 3r33524.  3r33333. 3r33524.  3r33333. If in the TD 2 radio module, each operates at its own frequency, free from interference (ACI, CCI, non-Wi-Fi interference), then there is a chance to get 90 Mbit /s in total for 1 TD. In reality, your neighbor and Wi-Fi affects the way that in the 2.4 GHz band to get 30 Mbit /s instead of 45 is good luck. 3r33524.  3r33333. 3r33524.  3r33333. Therefore, the total bandwidth of any TD with two radio modules in real conditions is 75 Mbit /s (on all clients connected to it). 3r33524.  3r33333. 3r33524.  3r33333.[Примечание переводчика]: from the point of view of the efficiency of using the spectrum of Wi-Fi is an extremely inefficient technology, as it initially implies competitive access to the environment for disparate devices in the public domain. For clarity, you can bring this figure. 3r33524.  3r33333. 3r33524.  3r33333. 3r3-300. 3r33524.  3r33333. 3r33524.  3r33333. 3rr3461. Marketers and salespeople

3r33524.  3r33333. Of course, the guys from the marketing departments may not understand the difference between the connection speed (data rate) and the bandwidth of the half-duplex channel. They may also want you to consider only the ideal, from the point of view of the radio signal conditions, where the mathematics looks like this: 3r32424.  3r33333. 3r33524.  3r33333. 3r33417.  3r33333. 3r33434. TD with two radio modules on 5 GHz 3-333617.  3r33333. 3r33434. 80 MHz channels (which are rarely, if ever, are used in Enterprise) and 1.3 Gbit /s with 3-336177.  3r33333. 3r33434. 1 MacBook Pro (3 × 3: 3) connected to each TD radio module. (only 2 nouta)
 3r33333. 3r33434. Both laptops download a large file, using full aggregation (A-MPDU + A-MSDU with large BlockAck)
 3r33333. 3r33434. The spectrum is perfectly clean (no ACI, no CCI, no other signals). (Dreams, dreams )
 3r33333. 3r33434. A NAS or a file server with an SSD onboard is connected to a 10G interface to the core network. 3r31717.  3r33333. 3r33434. Resource-intensive features are disabled on the AP, there are no problems with CPU loading. (This is quite possible)
 3r33333. 3r33434. Both client and TD drivers are highly optimized for bandwidth. 3r31717.  3r33333. 3r3619. 3r33524.  3r33333. 3rr3461. And you are offered to buy a switch with MGIG? 3r33462. 3r33524.  3r33333. In such a ridiculously unrealistic scenario, each of the two clients connects at a speed of 1.3 Gbit /s and has a bandwidth of 650 Mbps, which in the absence of interference will give 1.3 Gbit /s on the TD. Using this crazy scenario, salespeople convince to buy switches from 2.5 Gbit /s ports. 3r33524.  3r33333. 3r33524.  3r33333. With dual band 11ac /n TDs, in a busy Enterprise scenario where 20 MHz channels are used, to minimize the negative impact (contention) of your and neighboring TDs as much as possible, you can expect that the saturation of the air from both radio modules will occur before you end up in 100 Mbps port bandwidth. Remember that control and management frames have large overheads and the majority of frames carrying data have a size of about 256 bytes, which also adversely affects throughput. 3r33524.  3r33333. 3r33524.  3r33333. Three types of negative impact (contention) (not including ACI and non-Wi-Fi interference) can be called Intra-BSS, Inter-BSS and Client-to-Client. Your network can have a lot more contention than you think, especially if you didn’t spend time on network design and verification. Contention severely limits bandwidth. 3r33524.  3r33333. 3r33524.  3r33333. 3r3158. 3r33524.  3r33333. 3r33524.  3r33333. When someone from a vendor or his partner assumes that you need more than a 1 Gbps port on an AP, you should ask him the following: 3r3244.  3r33333. 3r33524.  3r33333. 3r33417.  3r33333. 3r33434. Please explain your calculation logic, according to which you assume that the client device, or a group of such devices can reach the speed of 1 Gbit /s. 3r31717.  3r33333. 3r3619. 3r33524.  3r33333. 3r33232.  3r33333. 3r33434. Beware that they will talk about channel speed (data rate) instead of throughput 3r3-3617.  3r33333. 3r33434. Beware that they will convince you that 80 MHz channels (or even 160) are good. Also beware of the half-truths that wide channels will give you more channel speed, which will give you less ether loading and more capacity. This is mistake. 3r31717.  3r33333. 3r33434. Beware that they will convince you that MU-MIMO is good. In practice, little sense. 3r31717.  3r33333.
3r33524.  3r33333. 3r33417.  3r33333. 3r33434. Please show me the data from the network of one of your customers who bought switches with 2.5 Gbit /s ports (or more) where you can see that traffic to the TD exceeded 1 Gbit /c by more than 15 minutes (which is also unlikely). 3r31717.  3r33333. 3r3619. 3r33524.  3r33333.

Does the old ???n live? 3r33462. 3r33524.  3r33333. If I myself have designed, configured and tested dual-band 11n 2 × 2: 2 Wi-Fi infrastructure now, where TDs have 100 Mbit /s uplinks, 95% of companies think that this network is the most remarkable of all that they have ever seen. I myself would prefer such a low-end, 2 × 2: ? 11n properly constructed network of 99% to poorly built 11ac Wave2 networks existing today.[Примечание переводчика]: new 11ac points have a large set of technologies that allow you to build what is called HD or high-density networks, but we always run into physics and mathematics. The same RxSOP is the last thing to tyunit
 3r33333. 3r33524.  3r33333. 3rr3461. What about 11ax? 3r33462. 3r33524.  3r33333. Arsen Bandurian already told, 3r3209. what not to expect from ???ax 3r33535. retelling the article by the same Devina Akina. But this topic should be raised again. 3r33524.  3r33333. 3r33524.  3r33333. HYIP has already begun, vendors have begun to release TD, although the standard has not yet been approved (expected by the end of 2019). 3r33524.  3r33333. Using wide channels is extremely inefficient in real-world conditions, as you can see in the figure below. Looking at 11ac 42 channel (36 - the main channel) from the bottom left you can see that the main channel (primary channel) is killed, and the second channels (secondary) are barely used. This is because 75% of Wi-Fi traffic is management, control and legacy data, and all of them are transmitted only on the main channel. 3r33524.  3r33333. 3r33524.  3r33333. The vast majority of customers are now 11n [/b] , so the second 40 MHz from the 80 MHz channel is basically not used at all. It is for this reason that 11ax was created. Efficiency creates a system-wide capacity and increases the throughput of each customer. The main objective of 11ax is to increase the bandwidth per client by 4 times, which can actually be achieved if: 3r32424.  3r33333. 3r33524.  3r33333. 3r33232.  3r33333. 3r33434. The 11ax clients
mostly work in the network.  3r33333. 3r33434. The network is superbly designed and configured
 3r33333.
3r33524.  3r33333. Which means most likely in 10 years it will happen. It takes a lot of time to get rid of old client devices. 11g customers who saw the light in 2003 are sometimes still at work. No matter what salespeople tell you that after 3 years everything will change, they should not be believed, the facts are talking about something else. 3r33524.  3r33333. 3r33524.  3r33333. 3rr3461. Do the 40 and 80 MHz channels help? No 3r33462. 3r33524.  3r33333. On the graph below, you can see how using large channels achieves high bandwidth per client device. 3r33524.  3r33333. 3r33524.  3r33333. . Do you need more than a gigabit on a copper port? Not. 3r33524.  3r33333. 3r33524.  3r33333.
Math is not lying

3r33524.  3r33333. These numbers are real. If you think differently, find the Enterprise network, where these numbers exceed the numbers I specified, show me them, and I will change this article. 3r33524.  3r33333. 3r33524.  3r33333. 3rr3461. Practical example 3r36262. 3r33524.  3r33333. [b] Effective simple rules 3r3496. which turned out to be very accurate, for calculating the bandwidth per device 1 are as follows: 3r32424.  3r33333. 3r33524.  3r33333. 3r33417.  3r33333. 3r33434. MCS rate × 50% /number of users[Одно устройство в сети]3r31717.  3r33333. 3r33434. MCS rate × 45% /number of users[Немного устройств, средняя нагрузка]3r31717.  3r33333. 3r33434. MCS rate × 40% /number of users[Много устройств, средняя и сильная нагрузка]3r31717.  3r33333. 3r3619. 3r33524.  3r33333. To help you understand better, let me give you [b] Example 3r3496. from one of my customers. 3r33524.  3r33333. They implemented 3 × 3: 3 TDs with 20 MHz channels to connect up to 100 active devices in each audience. The main application was unicast video with a 2 Mbit /c stream for 30 people per class. After successful implementation, they called me, communicating the thought that one TD was effective. The investigation revealed that client devices are to blame. In this class there were 30 iPad 1PPs that could not reach a speed of 2 Mbit /s on the operation of all 30 pieces. 3r33524.  3r33333. 3r33524.  3r33333. 3r33417.  3r33333. 3r33434. Channel Rate (Data Rate) = 72 Mbit /s 3r3-33617.  3r33333. 3r33434. 40% efficiency 3r31717.  3r33333. 3r33434. The total bandwidth of 29 Mbit /s
 3r33333. 3r33434. /30 = 950 Kbps to the device 3r361717.  3r33333. 3r3619. 3r33524.  3r33333. In another class, they used 30 iPad Air ? 2PPs and they worked well. 3r33524.  3r33333. 3r33524.  3r33333. 3r33417.  3r33333. 3r33434. Channel Rate (Data Rate) = 173 Mbit /s 3r3-33617.  3r33333. 3r33434. 40% efficiency 3r31717.  3r33333. 3r33434. The total bandwidth of 69 Mbit /s 3r3-3617.  3r33333. 3r33434. /30 = 2.3 Mbit /s per device 3r33617.  3r33333. 3r3619. 3r33524.  3r33333. His confusion was that the iPad c 1pp could not show the video adequately, and his MacBook Pro (3pp) received 145 Mbps at that moment, when the class was empty. 3r33524.  3r33333. 3r33524.  3r33333. 3r33417.  3r33333. 3r33434. Channel Rate (Data Rate) = 289 Mbit /s 3r3-33617.  3r33333. 3r33434. 50% efficiency 3r31717.  3r33333. 3r33434. The total bandwidth is 145 Mbit /s 3r3-3617.  3r33333. 3r33434. /1 = 145 Mbit /s per device 3r336177.  3r33333. 3r3619. 3r33524.  3r33333. 3rr3461. Imagine math works. And it will work for you too. 3r33462. 3r33524.  3r33333. [b] This article Devin ends r3r3496. 3r33524.  3r33333. From myself, Maxim Getman, I will add three life examples. 3r33524.  3r33333. 3r33524.  3r33333. 3rr3461. Factory 3r33462. 3r33524.  3r33333. The network for connecting bridge cranes is properly designed and configured, it works only in the 5 GHz band, and the clients are the core Cisco IW3702 TD in the WGB mode. On one TD 1562D, a maximum of 2 cranes are attached to the column. SNR below 40 dB is not lowered, the signal at the reception on both sides is about -60 dBm. Interference with significant duty cycle is not detected. A permanent 3-5M UDP stream comes from the Axis camera from the crane. In addition, kilobit traffic from the sensors and about 1M traffic to the crane operator's computer. This all works great. If 2 taps on a point, that's fine too. But if at the moment when the crane is on TD ? and we still load the network with iperf-ohm 10 Mbit /s UDP, then we observe losses of the order of 10-12%. It would seem that in theory with a 40 dB SNR, we should work on the MCS9 stably, both devices 11ac. 3r33524.  3r33333. 3r33524.  3r33333. Alas, in life there is work on the MCS3-? which gives, at 1PP, 20 MHz and a long guard interval (and in the iron shop it is impossible otherwise) 26 Mbit /s at worst. As a result, this corresponds to 13 Mbit /s of real traffic per 1 TD. Like this. The data is worse than the “office” formulas. This must be taken into account. 3r33524.  3r33333. 3r33524.  3r33333. Who can explain from the point of view of physics, why the DRS mechanism reduces speed so much, with a decent SNR, I will be glad to that. In my opinion, in the conditions of an iron shop clogged with iron, there are so many reflections that the DSP cannot parse the signal at the reception, does not send an ACK, and we get a reduction in speed. Oh yeah, the antennas on the TD are directional, 10 dBi. On crane clients omnidirectional, 7 dBi. Specificity is such that the direction is not done, fault tolerance should be. Working distance of 30-80 meters. So, expensive equipment, but not much to squeeze. 3r33524.  3r33333. 3r33524.  3r33333. 3rr3461. Large multi-purpose building with offices
3r33524.  3r33333. The building has a huge atrium inside, on several floors is common. In offices on the floors are points, not a few. In the atrium on the 1st floor can be heard points from 6 floors. What is the result? Even with a small load on the network, the bandwidth tends to zero. Especially at 2.4 GHz. In this case, I want to remind you about beacon overhead. If you have 5 SSIDs per point, low speeds are not removed (beacons are broadcast at a speed of 1 M), then at the point of space where 3 own points are heard on frequency channel ? 48% of the channel utilization is just from your beacons! There is something to think about? Turning off low speeds and at 12 M lower mandatory utilization of the channel will fall to 4.5% in the same conditions. Not bad, in order? 3r33524.  3r33333. 3r33524.  3r33333. What to do with the atrium? Design office points with antennas directed from the atrium, or at least take them away. And if they are already? Minimize the number of SSIDs, increase the available speeds and agree with the neighbors (if there are any) to do the same! 3r33524.  3r33333. 3r33524.  3r33333. 3rr3461. Exhibition Center. 3r33462. 3r33524.  3r33333. 20 TDs were installed on the pavilion, with more or less directional antennas, and they want to receive 1 M for each client, of which 500. 25 customers per TD. If we assume that we have a perfect broadcast and we can get 75 M for each TD, then everything seems to fit, even with a margin. 20x75 M = 1500 M, but you need only 500 M. Is it normal? Not! At what speed will motley clients connect? 3r33524.  3r33333. 3r33524.  3r33333. 3r33417.  3r33333. 3r33434. Channel Rate (Data Rate) = 52 Mbps (MCS? 1PP) 3r3-31717.  3r33333. 3r33434. 40% efficiency 3r31717.  3r33333. 3r33434. The total bandwidth of 20.8 Mbit /s 3r3-3617.  3r33333. 3r33434. /25 = 0.8 Mbit /s on the device 3r33617.  3r33333. 3r3619. 3r33524.  3r33333. Remember that it is in good conditions? How many channels are 2.4? 3 channels. How many channels on 5? 15 channels (and not all are available to all customers). We will at least receive CCI from our own TDs, especially at 2.4 GHz. Even if we reduce the number of SSIDs to 3x and turn off speeds below 12 M, the trouble of the exhibition is that everyone tries to bring his TP-Link, request a connection from the organizer by cable and broadcast, with default settings that will give overhead only beacons at 1M speed, and also ACI from the fact that the 3rd channel rose, out of ignorance. 3r33524.  3r33333. 3r33524.  3r33333. Here is what is happening on the air at 2.4 in the midst of the exhibition. Up to 90% utilization of -80 dBm. 3r33524.  3r33333. 3r33524.  3r33333. 3r33524.  3r33333. Knowledge and experience will help you build (if you are an integrator engineer) or order (if you are on the customer side) building a Wi-Fi network adequately. 3r33524.  3r33333. 3r33524.  3r33333. 3rr3461. Below I will give some useful Wi-Fi links to engineers:
3r33524.  3r33333. [b] Working Papers 3r3496. 3r33524.  3r33333. 1. 3r33469. Revolution Wi-Fi Capacity Planner
planner based on these most adequate formulas. will help to estimate precisely enough, and how many TDs need to connect N clients. 3r33524.  3r33333. 2. Table MCS 3r3-3838. will help determine the channel speed by MCS. 3r33524.  3r33333. 3.
Table of ratio of MCS and SNR will help to learn the MCS theoretically (worse in practice) 3r3524.  3r33333. 4. SSID Overhead Calculator lets you understand how the number of SSIDs and the speed of beacons affect 3r33535.  3r33333. 5. Table of opportunities for client devices allow you to know the device before their introduction 3r33524.  3r33333. 6. RSSI Compared helps to understand the variation in reception on different devices 3r33524.  3r33333. 3r33524.  3r33333. [b] Training materials 3r3496. 3r33524.  3r33333. 1. 3r3499. Ekahau Wi-Fi Design Tools
YouTube channel with the best webinars on the topic of Wi-Fi
 3r33333. 2. 3r3503. CWNA 5th edition 3r33538. . The best in the world tutorial on Wi-Fi. Cheaper Amazon will not find. The textbook is worth the money. 3r33524.  3r33333. 3. Technologies of modern wireless networks Wi-Fi . Tutorial. The actual textbook on Wi-Fi in Russian. It stands in the paper about the same as CWNA. Online pdf version is found. 3r33524.  3r33333. 4. 3r3- 3511. Wi-Fi Network Design for dummies
simple and understandable manual for those who are just starting. If you are a project manager, manager, and you do not have time to dive into the Wi-Fi jungle, read 50 pages of Wi-Fi Network Design for dummies in a few hours, and you will have an understanding of how Wi-Fi is being built right now. The allowance is free. 3r33524.  3r33333. 3r33524.  3r33333. If you are an engineer, which tutorial is more detailed, you ask? You can judge by the thickness. 3r33524.  3r33333. 3r33524.  3r33333. 3r33521. 3r33524.  3r33333. 3r33524.  3r33333. If you have interesting questions on the topic of Wi-Fi, it is easy to find my contacts. I will be glad to answer.
3r33333. 3r33333. 3r33333. 3r33535. ! function (e) {function t (t, n) {if (! (n in e)) {for (var r, a = e.document, i = a.scripts, o = i.length; o-- ;) if (-1! == i[o].src.indexOf (t)) {r = i[o]; break} if (! r) {r = a.createElement ("script"), r.type = "text /jаvascript", r.async =! ? r.defer =! ? r.src = t, r.charset = "UTF-8"; var d = function () {var e = a.getElementsByTagName ("script")[0]; e.parentNode.insertBefore (r, e)}; "[object Opera]" == e.opera? a.addEventListener? a.addEventListener ("DOMContentLoaded", d,! 1): e.attachEvent ("onload", d ): d ()}}} t ("//mediator.mail.ru/script/2820404/"""_mediator") () (); 3r? 3531. 3r33333.
3r33333. 3r33333. 3r33636. Only registered users can participate in the survey. 3r33537. Log in 3r33538. , you are welcome. 3r? 3539. 3r33333. 3r33333. 3r33542. 3r33333. 3r3544. 3r33333. 3r33546. Did you know about real Wi-Fi speed? 3r33613. 3r33333.
3r33333. 3r33333. 3r33552. 3r33333. 3r35454. 3r33333. 3r33556. 3r33333. 3r33558. 3r33333. 3r33333. 3r33561. 3r33333.
3r33333. 3r33333. 3r3608. 3r33333. 3r3333633. 3r3612. Yes, a famous topic. 3r33613. 3r33333. 3r3615. 3r33333. 3r31717. 3r33333.
3r33333. 3r33333. 3r3608. 3r33333. 3r3333633. 3r3612. No, I'm very surprised! I thought that air hygiene is a reality. 3r33613. 3r33333. 3r3615. 3r33333. 3r31717. 3r33333.
3r33333. 3r33333. 3r3608. 3r33333. 3r3333633. 3r3612. I knew, but I thought it was a little better. 3r33613. 3r33333. 3r3615. 3r33333. 3r31717. 3r33333.
3r33333. 3r33333. 3r3608. 3r33333. 3r3333633. 3r3612. The article is a blatant lie, hygienic Wi-Fi is possible, everything is in line for MGIG switches! 3r33613. 3r33333. 3r3615. 3r33333. 3r31717. 3r33333. 3r3619. 3r33333. 3r33333. 3r3622. 3r33333.
3r33333.
10 users have voted. posts.poll.no_abstained_yet.
3r33333.
3r33333. 3r33333. 3r33333. 3r33333.