On Mon, Mar 21, 2011 at 3:57 PM, Kucherenko Valeriy <darkside...@ukr.net> wrote: > I have a TP-Link TL-WN951N wireless PCI device (AR5008) and trying to make it > work in 802.11n mode with HT and MIMO. According to specifications ( > http://www.tp-link.com/products/productDetails.asp?class=&content=spe&pmodel=TL%2DWN951N > ) device supports 3*3 MIMO but I'm unable to enable spatial streams because > of ath9k driver. I have Ubuntu 10.10 with latest hostapd (compiled from git > and configured to support 802.11n) and installed > "linux-backports-modules-compat-wireless-2.6.37-2.6.35-28-generic" package > (which is latest available). The output of "iw list" command prints next > capabilities: > > Capabilities: 0x104e > HT20/HT40 > SM Power Save disabled > RX HT40 SGI > No RX STBC > Max AMSDU length: 7935 bytes > DSSS/CCK HT40 > > So there is no TX and RX STBC available. Even if I provide this options to > hostapd like "[TX-STBC][RX-STBC123]" the program is not starting with error > message stating that Driver does not support this modes. I'm interesting, > it's possible to enable spatial stream multiplexing for my device? Is there > any patch for ath9k driver or device is really does not support STBC and the > information provided at TP-Links site is false? > > Another problem is that when I enable HT40 mode I get connection speed > 300Mbps but connection quality and speed is awful. In HT20 mode I get real > 150Mbps, good connection and 5-6 mb/sec speed. I guess that the problem with > HT40 is linked to absense of STBC. Any thoughts?
STBC is not the same as spatial streams. http://en.wikipedia.org/wiki/Space%E2%80%93time_block_code >From the specs of the card, it looks as though it is capable of 3x3 MIMO, but with only two spatial streams, so it should handle MCS0 through MCS15. Check the output of "iw list" for a line like the following: HT TX/RX MCS rate indexes supported: 0-15 It is possible for a card to support multiple spatial streams without having support for space-time block coding. -Brian _______________________________________________ ath9k-devel mailing list ath9k-devel@lists.ath9k.org https://lists.ath9k.org/mailman/listinfo/ath9k-devel
