MIMO – What multiple antennas are all about
MIMO (Multiple Input Multiple Output) has been known for years from mobile communications technology, and this method has also been used in home networks for some time now. Unfortunately, the basic idea is still not at all or only partially known to many, so that I absolutely have to lose a few lines about it here. This is a multi-antenna method that can use several antennas at the same time for one transmission, so that everything can run more interference-free and, above all, faster. So far, so simple. But the devil is really in the details here now.
With MIMO, it is essential to distinguish between SU-MIMO and MU-MIMO. So far, so-called SU-MIMO (single-user MIMO) has been used on most devices. In theory, this works just as well with the 2, 3 or even 4 antennas, but there is a queue, because only one device can be operated per interval! With 10 devices, this results in a decent queue, which also creates a lot of overhead. And here it comes*s. Since everything is processed serially, it then happens, for example, that with a SU-MIMO-capable router with 4 antennas, a WLAN device with 4 antennas achieves 100% of the possible throughput in its interval, but an older stick with one antenna only 1/4, i.e. 25%. After all, both are never operated at the same time.
With MU-MIMO (Multiple-User-MIMO), ideally even several receivers can be served simultaneously! With 4 antennas, this is ideally 100% per interval with a suitable device. If you still have two devices with 2 antennas each, they can be operated simultaneously, i.e. in parallel, in the next interval. So, ideally, there could be up to four single devices. Whereby this case is rather rare. But parallel communication with multiple devices within a single interval reduces the number of intervals where a device has to wait for its turn again, sometimes dramatically. And since you never have just one device in the network, that’s usually a lot of wood. However, since the ideal case of full utilization due to interferences does not always occur, I have also taken these “gaps” into account symbolically in the scheme to be fair. Nevertheless, it only takes a little more than half the time for the same amount of data.
The WLAN router and any integrated WLAN access points should support MU-MIMO (Multi-User MIMO), have at least 4 antennas (4×4) and support the latest WiFi standard. Crossband repeating as an optional feature can be helpful and would be a useful addition. |
Router or access point?
So, either you set up a router with MU-MIMO and 4 antennas, or you use a corresponding access point, which is connected to the router via Ethernet cable. Operating an access point and a router with activated WLAN function at the same time does not really make sense in normal premises. Such an access point is actually only worthwhile if you want to expand an existing router that does not support MU-MIMO or has too few antennas. Then you turn off the WLAN in the router and only use the better access point.
Current routers, such as the FRITZ!Box 4060 here in the office can of course do that, you won’t need an extra access point. But if you really need throughput, you already need the best possible basis at this point – the mouse won’t bite off a thread. And you should of course try to buy the entire periphery from a single source so that you can be sure that everything harmonizes well. With a heavy heart, I also gave up so-called gaming routers and gaming access points because this very fast technology has not been able to cope with Telekom’s Entertain program (IP TV) after the changeover. Such incompatibilities should be planned for and checked from the start, otherwise it will be annoying in the end and you will have to buy twice again.
There is also always discussion why AVM, for example, generally sells (and advertises) all of its WLAN repeaters as repeaters only and does not also refer to the models with Ethernet ports as access points. Out-of-the-box, these parts are configured as simple WLAN repeaters and can be installed in a few minutes without any problems or training from Aunt Gerda in the party cellar. But these parts with the Ethernet jack are almost all not only simple WLAN repeaters that increase the range and to which you can also connect a device or switch via LAN cable, for example, but you could also reverse the whole thing after the changeover and put the router on the Ethernet port and let the repeater run as a real access point.
Older routers can continue to be used even with the WLAN function deactivated if a more modern access point that supports MU-MIMO and supports at least 4 antennas is connected to the Ethernet output (4×4). Some repeaters can also be used as an access point if you switch them over. |
Mesh is a must
A mesh WLAN is nothing else than a normal wireless local area network consisting of several WLAN components, but it has a huge difference to the conventional WLAN with competing sources, e.g. router and access point or integrated devices that can serve as WLAN access points like some power line adapters or WLAN repeaters. A mesh therefore only makes sense if you not only operate the router exclusively as a WLAN source, but also integrate more than one access point.
From the point of view of the end devices, the so-called mesh is a unified network, whereby the access points do not compete but complement each other. You don’t get double the speed, but you do get much more balanced area coverage, which can result in higher net throughput per device, no matter where you’re sitting or standing. In the current network, for example, I run a total of FRITZ!Box 4060 as a router, the fast FRITZ!Repeater 6000 each on the upper floor and ground floor, as well as four additional WLAN/PowerLAN components, including the FRITZ!Repeater 1200 AX, which is seen as an access point by the end devices in the WLAN. In addition, many repeaters also allow so-called crossband repeating. This can be quite useful for many devices, but must be set manually for suitable repeaters.
We see on the picture the “old” FRITZ!Repeater 2400 (powerless) and the newly set up FRITZ!Repeater 6000, which unfortunately is just like the FRITZ!Box 4060 does not offer direct wall mounting. This is more than annoying, so I had to move a cabinet again to the appropriate place to set up the repeater. Why is it there? The entrance door is made of wood and also the number of walls that would otherwise have to be penetrated upwards is reduced considerably, because the “counterpart” on the upper floor is now also behind an entrance door made of wood and the staircase is easier to penetrate than the bunker ceiling with suspended false ceiling and insulating floor substructure (continuous aluminum foil under the impact sound insulation) on the upper side. Since I later bought the second FRITZ!Repeater 6000 in the lab (see previous page) to the switch, a complete cable network is then also available upstairs, which now works almost ideally in terms of throughput.
The mesh functionality does not create a higher transmission rate than would theoretically be possible with a single connection , but it does create more uniform area coverage and thus also the opportunity to achieve the possible transmission rates everywhere in the first place. |
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