MIMO and spatial division multiplexing, space time block coding, maximal ratio compining, cyclic shift diversity

Hello there.

The TP Link WR802n V4 uses a MT7628 chipset ( datasheet available here: http://download.villagetelco.org/hardware/MT7620/MT7628%20datasheet.pdf ). On this datasheet, I can read that it uses maximal ratio combining (MRC) and space time block coding ( STBC ).

MRC is a technique involving the receiver to combine multiple copies of the safe signal to get the best SNR, while STBC is a technique involving both the receiver and the transmitter to improve the reliability of the data transfer.

The datasheet argues this is a 300 mbps router. It seems to me, with only the MRC and STBC techniques, it is limited to 150 mbps, as you have to use spatial division multiplexing (SDM), which sends independent and separately encoded data signals (streams) per antenna, to go from 150 mbps to 300 mbps in 802.11n.

So, here is the question: does the MT7628 uses SDM (and do not show it on the datasheet?) ? Do you know of 802.11 n / ac 2x2:2 (at least) routers that provide SDM?



Isn't STBC used to achieve SDM ?
The datasheet says "2T2R 2.4 GHz with 300 Mbps PHY data rate", so it must support 2 spatial streams.
Anyway, don't get your hopes up. I don't know about anyone else, but I had horrible experience with spatial streams. They are probably so pretentious, they work only in lab. I never exceeded 1/2 speed of a single spatial stream, despite the software reporting as much as 3 negotiated, 802.11n or 802.11ac.