802.11n Problem. MCS-15 not working.

RouterOS General
1

Seems like MCS-15 is not working on RB SXT v5.0 RC8. (2 spatial streams, 64 QAM, 5/6 coding rate)


Max tx/rx rate i get is 130 mbps (20 Mhz) or 270 Mbps (40 Mhz). This is only MCS-14 modulation scheme at 400 ns guard interval.

I had the two polarisation enabled. And a large signal / noise ratio (62 dB)


Other problem :

I tried to change MCS set through console, (it is not possible to do it via Winbox).

After reducing basic and supported rate to MCS0 - MCS2, i still was able to connect at MCS-14.


Atheros problem or did i miss something ?

2

what wireless protocol you are using?
270mbps is also mcs-15 with 800ns guard interval.

3

I’m using NV2, with HT Guard interval “any”.


HT Tx and RX chains 0 and 1 enabled.

We can see in the registered station window that HT40-7 (MCS15 ?) is not receiving packets.


4

NV2 only supports 800ms guard at this time. You will not get 300 / 150 only 270 / 135.

5

Ok, this is not clear inside Winbox as there are two settings for Guard Interval even if NV2 is active :

  • any

  • long

6

Those settings are ignored for Nv2. Nv2 doesn’t support short guard interval.

7

Ok.

They should be grayed out if not used, so that users are not confused.


Can be extended to other details inside Winbox.