The near future of Wi-Fi: how things are with 802.11ac
In the near future, Wi-Fi should get hold of three interesting improvements:
All of them are to some extent already available in real products and have the potential to become mass in the very near future. In this part, consider the 802.11ac. I have already written a review of this technology in general , and also provided a comparison of performance so that we focus on the applied aspects. In general, the adoption of 802.11ac as a standard is expected in early 2014, which did not prevent some companies from announcing chipsets last summer. The technology will enter the market in several stages, called “waves”.
Wave 1 products as of May 2013 have already been announced by a sufficiently large number of manufacturers of both consumer and business levels: Aruba , Cisco , Motorola Solutions , Ubiquiti , ASUS, D-Link, Linksys, NetGear, TP-Link and all all Some of them still exist only in the announcement stage, and some can already be bought. But is it worth it? Let's look at the pros and cons of this “gigabit Wi-Fi” and try to understand.
Increased transfer rate. Everything is clear here - the network is faster, everyone is happy. Just need to remember that support is needed on the client. Let's see what is needed to “break the gigabit barrier” on Wave1 equipment. In order not to go far, let's turn to the speed plate from Wikipedia
Even with 80MHz channels and the correct placement of points, you should not count on gigabit speeds. Most compact clients will not support three streams. Smartphones usually support 1 stream, tablets - 1-2 streams, laptops - 2-3 streams. This is important to remember when planning a network and not chasing speeds that customers simply cannot support. With Wave2 and MU-MIMO, however, "low-flow" clients will be processed much more efficiently. For example, a point with 4SS will be able to transmit in parallel to 4 clients from 1SS (downstream for each) or to three clients in combination 1 + 2 + 1, etc. This should significantly improve the efficiency of the use of airtime and increase the network capacity. About this below.
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Increased radio sensitivity. The new chipsets (both on the points and on the clients) have better sensitivity, therefore, it is considered that for the successful operation of 256-QAM (and to achieve higher speeds) it will not be necessary to increase the coating density. Please note that this does not apply to MIMO in any way, and there’s no need to rely on the honesty of the manufacturers of super-cheap client devices.
An important nuance is also a wire connection points . The 802.11n dot can “squeeze” a maximum of 900Mbps from two radios (3x3: 3 / 40Mhz), for which one GE link is enough. Point 802.11ac Wave 1 can theoretically squeeze 2x1300Mbps = 2.6Gbps, which is not enough even for three GE links (and Wave2 is generally all 7Gbps). Upgrade everything to 10GE? It will be quite expensive. Fortunately (at least for Wave 1) this is not necessary. It is important to remember that Ethernet bandwidth is historically measured with the overhead of the protocol itself (“net”), and for Wi-Fi - without (“gross”). So the theoretical “raw” 2600Mbps is quite realistic to cram into 2 GE links. Most of the announced 802.11ac Wave 1 points have 2 GE ports and this is considered to be enough. However, you will have to pay extra for additional ports on the switches and laying a second cable (usually ~ 50% of the cost of laying the first). Again, if we build a network for BYOD (i.e., customers will support 1-2 streams), then one gigabit can be enough.
Increased network capacity. A useful side effect of the increased speed is that transferring the same amount of data takes less time :) Thus, the capacity of our half-duplex cell increases. Suppose we have a number of 802.11n 1x1: 1 / 40MHz clients (150Mbps) on the access point, each of which requires 10Mbps bandwidth. For convenience of calculations, we assume that the effective cell throughput will be 0.6 of the theoretical = 90Mbps. With half-duplex exchange, thus, the cell will be able to support 9 clients. When upgrading to 802.11ac, keeping the channel width and the number of streams, we can get a theoretical 200Mbps per cell at the expense of 256-QAM, raising the capacity to 200 * 0.6 / 10 = 12 clients. There is an increase of 30% simply due to the replacement of iron. If you think, by the way, the cell capacity does not depend on whether you have a 2x2: 2 or 3x3: 3 point, because with half duplex transmission for a 1x1: 1 client, the remaining streams are not used. But with Wave2 and MU-MIMO in the same scenario, we can easily turn 12 clients into 36 or 48. And at 8x8: 8 - in general, in 96!
Basically, that's all the main factors.
Comparing the factors, one can understand when the transition to 802.11ac is profitable, and when - no.
The first factor is purely economic. If the increased speed and capacity (which we have learned to estimate) really justify the additional cost (which we can now estimate), the transition makes sense.
The second factor is strategic. Buy Wave1 now or wait for Wave2 then? A month ago, I would say that waiting for Wave2 is probably not worth it, because the output of the equipment is scheduled for 2015. However, only last week Wave2 4x4: 4 MU-MIMO chipset was announced!
Considering, after the announcement of the first 802.11ac chipsets, the first Wave1 products appeared in ~ six months in the consumer sector and less than a year later in the corporate one - it is quite possible that at this time next year we will already be testing Wave2 with might and main. So, if there is no urgent need - it is worth considering the possibility of jumping directly to Wave2.
Again, 4x4: 4 MIMO will still need to be launched, and MU-MIMO only makes sense for relatively low-powered clients, and the wired infrastructure upgrade will definitely have to be done. If you want to build a network for laptops or do a wireless takeaway right now - Wave1 is fine.
There is a third option . With the release of equipment 802.11ac from the current equipment 802.11n flies "raid novelty", and with it the charge for the slope. Thus, for those who have matured to upgrade from 802.11a / b / g (or for those who do not have a network at all), the option of inexpensively switching to 802.11n may be suitable if it suits the performance (warehouses, retail, hotspots, etc. .). For them, much more relevant may be other innovations: Passpoint and Voice Enterprise, which will be discussed in the following articles.
PS All of the above applies mainly to corporate networks, but can also be applied to the home. Just remember that radio planning for the home is still a joy , most Internet connections are still not faster than 802.11n, and tablets and phones hardly digest more than 65Mbps. So, there is no particular benefit from upgrading everything and everything for a home on 802.11ac Wave 1 (for now).
- 802.11ac (aka “Gigabit Wi-Fi”) as a means of increasing WLAN speed and capacity
- Wi-Fi Certified Passpoint (also known as Hotspot 2.0) based on the 802.11u specification, as a way to significantly improve the situation with hotspot and unload cellular networks.
- Wi-Fi Certified Voice Enterprise : as a way to restore order in the situation with the construction of high-performance networks for voice and video. An excellent infrastructure can be built now, but the lack of strict standards for client devices creates problems with the performance of the solution as a whole.
All of them are to some extent already available in real products and have the potential to become mass in the very near future. In this part, consider the 802.11ac. I have already written a review of this technology in general , and also provided a comparison of performance so that we focus on the applied aspects. In general, the adoption of 802.11ac as a standard is expected in early 2014, which did not prevent some companies from announcing chipsets last summer. The technology will enter the market in several stages, called “waves”.
- Wave 1 allows you to break through the gigabit barrier of a “raw” data transfer rate (~ 1300 theoretical Mbps at 3x3: 3 MIMO with a channel width of 80MHz and a new 256-QAM modulation). In general, the same 802.11n, but faster.
- Wave 2 will bring further improvements in terms of speed (4x4: 4 MIMO / 160MHz ~ = 3500Mbps) and capacity - MU-MIMO.
- Subsequent waves may bring other innovations that are considered optional or too complex for quick implementation (such as 8x8: 8 MIMO). But they may not bring it at all - quite a few technologies described in the 802.11n standard have not been implemented in real products.
Wave 1 products as of May 2013 have already been announced by a sufficiently large number of manufacturers of both consumer and business levels: Aruba , Cisco , Motorola Solutions , Ubiquiti , ASUS, D-Link, Linksys, NetGear, TP-Link and all all Some of them still exist only in the announcement stage, and some can already be bought. But is it worth it? Let's look at the pros and cons of this “gigabit Wi-Fi” and try to understand.
Increased transfer rate. Everything is clear here - the network is faster, everyone is happy. Just need to remember that support is needed on the client. Let's see what is needed to “break the gigabit barrier” on Wave1 equipment. In order not to go far, let's turn to the speed plate from Wikipedia
- With a channel width of 20MHz , the maximum speed per stream is ~ 87Mbps , which means that with the current limit of 3 streams, we cannot see gigabit.
- With a channel width of 40MHz , the maximum speed per stream is ~ 200Mbps , which means that with the current limit of 3 streams, we cannot see gigabit. But, compared to 802.11n, we accelerated by a third (600/450) simply by replacing iron.
- With a channel width of 80MHz , the maximum speed per stream is ~ 433Mbps , which means that we need to use all 3 streams. This imposes rather strict requirements on the coverage plan: you need to provide 80MHz channels (non-overlapping for neighboring cells, so we need at least 4 and where to find them?), Plus, we need to provide a favorable environment for three spatial streams, which is not very simple.
Even with 80MHz channels and the correct placement of points, you should not count on gigabit speeds. Most compact clients will not support three streams. Smartphones usually support 1 stream, tablets - 1-2 streams, laptops - 2-3 streams. This is important to remember when planning a network and not chasing speeds that customers simply cannot support. With Wave2 and MU-MIMO, however, "low-flow" clients will be processed much more efficiently. For example, a point with 4SS will be able to transmit in parallel to 4 clients from 1SS (downstream for each) or to three clients in combination 1 + 2 + 1, etc. This should significantly improve the efficiency of the use of airtime and increase the network capacity. About this below.
')
Increased radio sensitivity. The new chipsets (both on the points and on the clients) have better sensitivity, therefore, it is considered that for the successful operation of 256-QAM (and to achieve higher speeds) it will not be necessary to increase the coating density. Please note that this does not apply to MIMO in any way, and there’s no need to rely on the honesty of the manufacturers of super-cheap client devices.
An important nuance is also a wire connection points . The 802.11n dot can “squeeze” a maximum of 900Mbps from two radios (3x3: 3 / 40Mhz), for which one GE link is enough. Point 802.11ac Wave 1 can theoretically squeeze 2x1300Mbps = 2.6Gbps, which is not enough even for three GE links (and Wave2 is generally all 7Gbps). Upgrade everything to 10GE? It will be quite expensive. Fortunately (at least for Wave 1) this is not necessary. It is important to remember that Ethernet bandwidth is historically measured with the overhead of the protocol itself (“net”), and for Wi-Fi - without (“gross”). So the theoretical “raw” 2600Mbps is quite realistic to cram into 2 GE links. Most of the announced 802.11ac Wave 1 points have 2 GE ports and this is considered to be enough. However, you will have to pay extra for additional ports on the switches and laying a second cable (usually ~ 50% of the cost of laying the first). Again, if we build a network for BYOD (i.e., customers will support 1-2 streams), then one gigabit can be enough.
Increased network capacity. A useful side effect of the increased speed is that transferring the same amount of data takes less time :) Thus, the capacity of our half-duplex cell increases. Suppose we have a number of 802.11n 1x1: 1 / 40MHz clients (150Mbps) on the access point, each of which requires 10Mbps bandwidth. For convenience of calculations, we assume that the effective cell throughput will be 0.6 of the theoretical = 90Mbps. With half-duplex exchange, thus, the cell will be able to support 9 clients. When upgrading to 802.11ac, keeping the channel width and the number of streams, we can get a theoretical 200Mbps per cell at the expense of 256-QAM, raising the capacity to 200 * 0.6 / 10 = 12 clients. There is an increase of 30% simply due to the replacement of iron. If you think, by the way, the cell capacity does not depend on whether you have a 2x2: 2 or 3x3: 3 point, because with half duplex transmission for a 1x1: 1 client, the remaining streams are not used. But with Wave2 and MU-MIMO in the same scenario, we can easily turn 12 clients into 36 or 48. And at 8x8: 8 - in general, in 96!
Basically, that's all the main factors.
- On the one hand: increased speed and capacity
- On the other hand: the speed is not always reached, the clients and points need to be replaced (and those and those will be more expensive), the wired part needs to be upgraded, everything purchased will have to be changed again when Wave2 exits.
Comparing the factors, one can understand when the transition to 802.11ac is profitable, and when - no.
The first factor is purely economic. If the increased speed and capacity (which we have learned to estimate) really justify the additional cost (which we can now estimate), the transition makes sense.
The second factor is strategic. Buy Wave1 now or wait for Wave2 then? A month ago, I would say that waiting for Wave2 is probably not worth it, because the output of the equipment is scheduled for 2015. However, only last week Wave2 4x4: 4 MU-MIMO chipset was announced!
Considering, after the announcement of the first 802.11ac chipsets, the first Wave1 products appeared in ~ six months in the consumer sector and less than a year later in the corporate one - it is quite possible that at this time next year we will already be testing Wave2 with might and main. So, if there is no urgent need - it is worth considering the possibility of jumping directly to Wave2.
Again, 4x4: 4 MIMO will still need to be launched, and MU-MIMO only makes sense for relatively low-powered clients, and the wired infrastructure upgrade will definitely have to be done. If you want to build a network for laptops or do a wireless takeaway right now - Wave1 is fine.
There is a third option . With the release of equipment 802.11ac from the current equipment 802.11n flies "raid novelty", and with it the charge for the slope. Thus, for those who have matured to upgrade from 802.11a / b / g (or for those who do not have a network at all), the option of inexpensively switching to 802.11n may be suitable if it suits the performance (warehouses, retail, hotspots, etc. .). For them, much more relevant may be other innovations: Passpoint and Voice Enterprise, which will be discussed in the following articles.
PS All of the above applies mainly to corporate networks, but can also be applied to the home. Just remember that radio planning for the home is still a joy , most Internet connections are still not faster than 802.11n, and tablets and phones hardly digest more than 65Mbps. So, there is no particular benefit from upgrading everything and everything for a home on 802.11ac Wave 1 (for now).
Source: https://habr.com/ru/post/181297/
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