Your expectation would be right if all devices (the foreign ones, too) would agree to use MAXtream. AirTime is not necessarily divided equally (unless all devices use a common TDMA technique), but your AP-STA1-STA2 combination will get nearly the same AirTime an AP-STA combination will if the channel is overcrowded.

The devices just listen before talking and if the channel is free, they allocate it. If the channel is occupied, they try again after a short delay. Thus, if you already experience loss of bandwidth due to fewer AirTime for your devices, your two STAs would need to more or less share the AirTime left by other devices inside the angle of the beam width (maybe a little more, but not much).

IMO, it's not worth to try this, since the bottleneck clearly is the common channel. If you use AP-STA combination, available AirTime increases for all. I'm pretty sure, bandwidth with an AP-STA1-STA2 combination would make the situation worser for all devices while resulting in only marginal more AirTime for your link.

@R1D2 which indeed makes sense, but given that WiFi TCP flows are dynamically bound to time - i.e. small chunks of data are transmitted rather than huge continuous transfers - I'd be increasing my chances of getting more of that remaining AirTime with twice as many CPEs asking for it, dont' you think?

Notwithstanding the fact that TP-Link is running late in the 802.11ac business in the EU and most parts of the world (excluding China) I'd be forced to migrate some of my links to other vendors in pursue of higher QAM encodings that among others provide further optimizations to the 802.11 protocol on the same channel widths..

Sure, but other devices woud store more data which needs to be sent out, too, and if they allocate the channel, your CPEs need to wait a little longer, too, thus resulting in lower bandwidth for all devices. I did experience this with CPE210 and ~120 other devices inside the beam angle. Bandwidth did drop and interferences did raise significantly the more devices were in sight.

My solution for stationary backhauls is to apply for a license so I can use the non-public frequency range from 5755 to 5875 MHz. Unfortunately, CPEs > hardware V1 don't allow me to use this channels in my region.

@R1D2 and how - may i ask - do I go about using these channels on v1.0/1.1 CPEs seeing that there's no respective function on the UI? Do i have to get in touch with TP-Link directly to provide credentials and proof and somehow this is then enabled? Also my understanding it that these frequencies apply to Short Range Devices only and are limited to 25mW EIRP...?

In my country they can be used for commercial links with up to 4W (36 dBm) – but not SRD – and they can be used with CPEs in Test mode:

R1D2 wrote

In my country they can be used for commercial links with up to 4W (36 dBm) – but not SRD – and they can be used with CPEs in Test mode:

 

@R1D2 I'm familiar with Test_Mode, however i was under the impression that the EU and Germany share legislation on the 5Ghz band C / FWA spectrum band. Can't find any quick info on said channels being available for non-SRD / 4W commercial links, could you post some links - it'd be useful reference..thanks! While at it could you also provide some insight with regards to costs involved in securing such a permit for a 20Mhz channel width?

@RTouris, I have only the assignment from regulation authority in german language. Does this help?

As I understand, there are no costs for the license. You just need to register your company with the regulation authority (Bundesnetzagentur) and your use has to be a commercial, stationary distribution system to supply public end-users. Then you register the place where you want to install the system and they decide to grant you permission (or probably not) for a stationary broadband distribution system (Broadband Fixed Wireless Access BFWA).

@R1D2 This is weird in terms of parity between the member-states of the EU...In the UK (granted not a full-member / Brexit-aside) Ofcom regulates the licensed use of Band C and apparently this costs GBP50/year for 20terminals...So apparently this is different in Germany and I expect a similar pattern in other member-states...I find it difficult to source info for my country, so I take it it's not allowed to use Band C here, even for SRD applications. Oh well...

@RTouris, in fact, no member-state of the EU is a »full member«. EU just »harmonizes«, makes so-called »guidelines«. No state is required to implement their recommendations ...

Anyway, there must be a regulation authority in Greece, too. Ministry for telecommunication or something like this?

@R1D2 Sure there is, it's called EETT (National Telecoms & post/carriage Commitee), but they don't provide any info on the licensed 5Ghz band on-line (that i could find), merely stating that (the unlicensed 5Ghz spectrum) is free to use as long as it linited to channels 100-140 with DFS/TPC. No info on FWA / Band C whatsoever...Might give them a call someday to request further guidance.